EPA 625/1-77-008
(COE EM1110-1-501)
                         PROCESS DESIGN MANUAL
                                  FOR
                           LAND TREATMENT OF
                         MUNICIPAL WASTEWATER
                U.S. ENVIRONMENTAL PROTECTION AGENCY
              Environmental Research Information Center
                         Technology Transfer
                Office of Water Program Operations
                    U.S. ARMY CORPS OF ENGINEERS
                   U.S. DEPARTMENT OF AGRICULTURE
                            October 1977

-------
                             ACKNOWLEDGMENTS

There  were  three  groups of participants involved in the preparation of
this  manual:    (1)  the contractor-authors, (2) an interagency workgroup,
and  (3)  the  group  of  experts  and  invited reviewers.  The interagency
workgroup  defined  the  scope  of  the  effort,  guided  the work of the
contractor,  and  was  responsible  for manual review.  The membership of
each group is listed below.

CONTRACTOR:  Metcalf & Eddy,  Inc., Palo Alto, California

Supervision:   C. Pound, Vice  President

Senior Author:   R. Crites, Project Manager

Staff Authors:  J.  Esmay,  D.  Griffes,  J. Olson, J. Powers, R. Shedden, R.
               Smith,  A. Uiga

Consultant Authors:  Dr. F. Broadbent,  University of California, Davis
                    Dr. P. Pratt,  University of California, Riverside
                    Dr. A. Wallace,  University of Idaho
                    Dr. J. Melnick,  Dr. C. Gerba, Dr. S. Goyal,
                           Baylor  University
                    Dr. R. Burau,  University of California, Davis
INTERAGENCY WORKGROUP

Chairmen:   B.  Seabrook,  OWPO,  EPA
           N.  Urban,  COE

Deputy Chairmen:   R.  Bastian,  OWPO,  EPA
                  S.  Reed,  CRREL,  COE

Project Officer:   Dr. J.E.  Smith,  Jr.,
                  ERIC,  EPA

Members:  W.  Whittington,  OWPO,  EPA
          R.  Thomas,  RSKERL,  EPA
          R.  Dean, Region  VIII,  EPA
          H.  Thacker, OALWU,  EPA
          C.  Rose, FHA,  USDA
          G.  Loomis,  USDA
          R.  Duesterhaus,  USDA
          Dr.  J.  Parr, ARS, USDA
          Dr.  P.  Hunt, ARS, USDA
          Dr.  W.  Larson, ARS,  USDA
          Col.  T.  Bishop,  COE
          D.  Knudson, COE
          Dr.  H.  McKim,  CRREL, COE
EXPERTS AND INVITED REVIEWERS

Dr. H. Bouwer, Director, WCL,
  USDA/ARS
Dr. C. Lance, ARS, USDA
Dr. R. Loehr, Cornell
  University
Dr. W. Jewell, Cornell
  University
Dr. T. Hinesly, University
  of Illinois
Dr. M. Kirkham, Oklahoma
  State University
Dr. E. Lennette, M.D.,
  California Health Department
E. Sepp, California Health
  Department
Lt. Col. V. Ciccone, USAMD
Capt. J. Glennon, USAMD
H. Pahren, HERL, EPA
Dr. C. Enfield, RSKERL, EPA
Dr. L. Carpenter, M.D., Former
  Director, Oklahoma State
  Health Department
R. Sletten; A. Palazzo;
  J. Bouzon; CRREL, COE
Dr. R. Lee, USAE, WES, COE
R. Madancy, OWRT, USD I
J. Dyer, OWRT, USD I

-------
                                 ABSTRACT
This  manual   presents  a  rational   procedure  for  the  design  of land
treatment  systems.   Slow  rate,  rapid  infiltration, and overland flow
processes  for the treatment of municipal  wastewaters are given emphasis.
The basic unit operations and unit processes are discussed in detail, and
the design concepts and criteria are presented.


The  manual  includes  design  examples  as  well   as  actual  case study
descriptions  of  operational systems.   Information on planning and field
investigations  is  presented  along with the process design criteria for
both large and small scale systems.
                                  m

-------
                                CONTENTS


Chapter                                                              Page

            ACKNOWLEDGMENTS                                           i i

            ABSTRACT                                                 11i

            CONTENTS                                                  iv
            FIGURES                                                 viii

            TABLES                                                   xii

            FOREWORD                                               xviii

   1        INTRODUCTION

            1.1  Background and Purpose                              1-1
            1.2  Objectives                                          1-3
            1.3  Scope of the Manual"                                 1-3
            1.4  Guide to Intended Use                               1-4
            1.5  References                                          1-5

   2        TREATMENT PROCESS CAPABILITIES AND OBJECTIVES

            2.1  Introduction                                        2-1
            2.2  Slow Rate Process                                   2-1
            2.3  Rapid Infiltration                                  2-9
            2.4  Overland Flow                                       2-11
            2.5  Other Processes                                     2-14
            2.6  References                                          2-19

   3        TECHNICAL PLANNING AND FEASIBILITY ASSESSMENT

            3.1  Purpose and Scope                                   3-1
            3.2  Approach to Development of Alternatives             3-2
            3.3  Evaluation of Unit Processes                        3-4
            3.4  Wastewater Quality                                  3-12
            3.5  Regional Site Characteristics                       3-15
            3.6  Other Planning Considerations                       3-31
            3.7  Evaluation of Alternative Systems                   3-44
            3.8  References                                          3-57

   4        FIELD INVESTIGATIONS
            4.1  Introduction                                        4-1
            4.2  Wastewater Characteristics                          4-2
            4.3  Soil Physical and Hydraulic Properties              4-2
            4.4  Soil Chemical Properties                            4-2
            4.5  Other Field Investigations                          4-4
            4.6  References                                          4-9

-------
                          CONTENTS (Continued)

Chapter                                                              Page

   5        PROCESS DESIGN

                                                                     5-1
                                                                     5-26
                                                                     5-30
                                                                     5-38
                                                                     5-70
                                                                     5-77
                                                                     5-94
                                                                     5-99
                                                                     5-102
                                                                     6-1
                                                                     6-1
                                                                     6-14
                                                                     6-22
                                                                     6-28
                                                                     7-1
                                                                     7-2
                                                                     7-10
                                                                     7-18
                                                                     7-26
                                                                     7-32
                                                                     7-41
                                                                     7-44
                                                                     7-53
                                                                     7-60
                                                                     7-67
                                                                     7-71
                                                                     7-76
                                                                     7-77
   8
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
SMALL
6.1
6.2
6.3
6.4
6.5
CASE
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
7.11
7.12
7.13
7.14
Land Treatment Process Design
Preappli cation Treatment
Storage
Distribution
Management of Renovated Water
Vegetation
System Monitoring
Facilities Design Guidance
References
SYSTEMS
General Considerations
Design Procedures
Facilities Design
Small System Design
References
STUDIES
Introduction
Pleasanton, California
Walla Walla, Washington
Bakersfield, California
San Angelo, Texas
Muskegon, Michigan
St. Charles, Maryland
Phoenix, Arizona
Lake George, New York
Fort Devens, Massachusetts
Pauls Valley, Oklahoma
Paris, Texas
Other Case Studies
References
DESIGN EXAMPLE
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
Introduction
Statement of Problem
Design Data
Process Alternatives
Preliminary Performance Estimate
Cost Comparison
Process. Design
References
                                                                     8-1
                                                                     8-1
                                                                     8-1
                                                                     8-8
                                                                     8-12
                                                                     8-15
                                                                     8-16
                                                                     8-25

-------
                            CONTENTS (Continued)

Appendix                                                             Page

   A        NITROGEN

            A.I   Introduction                                       A-l
            A.2   Nitrogen Transformations                           A-l
            A.3   Nitrogen Removal from the Soil  System              A-9
            A.4   Nitrogen Removal with Various Application Systems  A-21
            A.5   Summary                                            A-28
            A.6   References                                         A-29

   B        PHOSPHORUS

            B.I   Introduction                                       B-l
            B.2   Removal Mechanisms                                 B-2
            B.3   Phosphorus Removal by Land Treatment Systems       B-10
            B.4   Models                                             B-19
            B.5   References                                         B-27

   C        HYDRAULIC CAPACITY

            C.I   Introduction                                       C-l
            C.2   Hydraulic Properties                               C-l
            C.3   Soil Infiltration Rate and
                   Permeability Measurements                         C-l2
            C.4   Groundwater Flow Investigations                    C-31
            C.5   Groundwater Mound Height Analysis                  C-35
            C.6   Control of the Groundwater Table                   C-44
            C.7   Relationship Between Measured Hydraulic
                   Capacity and Actual Operating Capacity            C-46
            C.8   References                                         C-47

   D        PATHOGENS
            D.I   Introduction                                       D-l
            D.2   Relative Public Health Risk                        D-l
            D.3   Pathogens Present in Wastewater                    D-l
            D.4   Bacterial Survival                                 D-6
            D.5   Virus Survival                                     D-9
            D.6   Movement and Retention of Bacteria in Soil         D-ll
            D.7   Movement and Retention of Viruses in Soil          D-14
            D.8   Potential Disease Transmission Through
                   Crop Irrigation                                   D-20
            D.9   Potential Disease Transmission by Aerosols         D-22
            D.10  References                                         D-25

   E        METALS

            E.I   Introduction                                       E-l
            E.2   Metals in Wastewater                               E-l
            E.3   Receiving Soils                                    E-6
            E.4   Chemistry of Metals in Soil                        E-10
            E.5   Environmental Benefits from Metal
                   Addition to Soil                                  E-19
                                   VI

-------
                            CONTENTS (Concluded)
Appendixes
E.6   Environmental Impact from Metal
       Addition to Soil
E.7   References

FIELD INVESTIGATION PROCEDURES

F.I   Introduction
F.2   Crop Water Requirements
F.3   Soil Investigations
F.4   References
                                                         Page
                                                                     E-22
                                                                     E-35
                                                                     F-l
                                                                     F-l
                                                                     F-4
                                                                     F-21
            GLOSSARY. CONVERSION FACTORS, AUTHOR INDEX,
            SUBJECT INDEX

-------
                                 FIGURES


No.                                                                  Page

2-1    Slow Rate Land Treatment                                      2-5
2-2    Rapid Infiltration                                            2-10
2-3    Overland Flow                                                 2-13
2-4    Subsurface Application to Soil  Mound Over Creviced Bedrock    2-18
3-1    Planning Sequence for the Development of Land Treatment
        Alternatives                                                 3-3
3-2    Potential Evapotranspiration Versus Mean Annual
        Precipitation                                                3-6
3-3    Soil Permeability Versus Ranges of Application Rates for
        Slow Rate and Rapid Infiltration Treatment                   3-7
3-4    Examples of Combined Systems                                  3-9
3-5    Total Land Requirement (Includes Land for Application,
        Roads, Storage, and Buildings)                               3-11
3-6    Estimated Wastewater Storage Days Based Only on Climatic
        Factors                                                      3-13
3-7    Proportions of Sand, Silt, and Clay in the Basic Soil-
        Textural Classes                                             3-22
3-8    Dominant Water Rights Doctrines and Areas of Water
        Surplus or Deficiency                                        3-33
3-9    Public Acceptability of Renovated Water Reuse                 3-43
4-1    Closed and Open Barrel Augers and Tiling Spade                4-6
4-2    Soil Profile With Two Horizons                                4-7
4-3    Typical Drill Rig Used for Soil Borings                       4-8
5-1    Slow Rate Design Procedure                                    5-5
5-2    Rapid Infiltration Design Procedure                           5-11
5-3    Effect of Infiltration Rate on Nitrogen Removal for
        Rapid Infiltration, Phoenix, Arizona                         5-15
5-4    Overland Flow Design Procedure                                5-18
5-5    Principal Nitrogen Transformations in Wetlands                5-24
5-6    Wetland System at Brillion Marsh, Wisconsin                   5-25
5-7    Determination of Storage by EPA Computer Programs and
        Water Balance According to Climatic Constraints              5-32
5-8    Surface Distribution Methods              .                    5-40
5-9    Plastic Siphon Tube for Furrow Irrigation                     5-45
5-10   Aluminum Hydrant and Gated Pipe for Furrow Irrigation         5-46
5-11   Outlet Valve for Border Strip Application                     5-49
5-12   Natural Drainage of Renovated Water Into Surface Water        5-50
5-13   Rapid Infiltration Basin Influent Structure                   5-51
5-14   Overland Flow Slope (8%) at Utica, Mississippi                5-52
5-15   Alfalfa Valve Characteristics                                 5-54
5-16   Orchard Valve Characteristics                                 5-55
5-17   Hand Moved Sprinkler Systems                                  5-57
5-18   Mechanically Moved Sprinkler System                           5-58
5-19   Permanent Solid Set Sprinkler System                          5-59
5-20   Stationary Gun Sprinkler Mounted on a Tractor Trailer         5-61
5-21   Traveling Gun Sprinkler                                       5-62
5-22   Side Wheel Roll Sprinkler System                              5-63
5-23   Center Pivot Rig                                              5-64

-------
                           FIGURES (Continued)

No.                                                                  Page

5-24   Center Pivot Irrigation System                                5-64
5-25   Rotating Boom, Fan Sprinkler, Ada, Oklahoma                   5-66
5-26   Collection of Renovated Water by Drain                        5-73
5-27   Trenching Machine for Installation of Drain Tile              5-74
5-28   Plan and Cross Section of Two Parallel Recharge Basins
        With Wells Midway Between Basins                             5-75
5-29   Effect of Selected Vegetation on Soil Infiltration Rates      5-78
5-30   Infiltration Rates for Various Crops                          5-79
5-31   Crop Growth and Nitrogen Uptake Versus Days From Planting
        for Forage Crops Under Effluent Irrigation                   5-84
5-32   Schematic of Groundwater Flow Lines and Alternative
        Monitoring Well Locations                                    5-97
6-1    Small System Design Procedure                                 6-3
6-2    Estimated Wastewater Storage Days Based Only on Climatic      6-4
        Factors
6-3    Schematic for Typical  Slow Rate System                        6-15
6-4    Schematic for Typical  Rapid Infiltration System               6-19
6-5    Schematic for Typical  Overland Flow System                    6-21
6-6    Bubbling Orifice Distribution for Overland Flow               6-22
7-1    Land Treatment System, City of Pleasanton                     7-4
7-2    Irrigated Pasturelarid, Pleasanton, California                 7-6
7-3    Portable Sprinkler System, Pleasanton, California             7-6
7-4    Schematic Flow Diagram, Wastewater Treatment Plant,
        Walla Walla, Washington                                      7-13
7-5    Large Diameter Sprinkler Gun for Industrial Wastewater
        Application Used at Walla Walla, Washington                  7-16
7-6    Alfalfa Harvesting Equipment, Sprinkler Riser, and
        Impact Head at City Irrigation Site, Walla Walla,
        Washington                                                   7-16
7-7    Existing Wastewater Irrigation System, Bakersfield,
        California                                                   7-21
7-8    Proposed Wastewater Irrigation System, Bakersfield,
        California                                                   7-25
7-9    Slow Rate Land Treatment System at San Angelo, Texas          7-28
7-10   Coastal Bermuda Grass  Hay at San Angelo, Texas                7-29
7-11   Border Strip Irrigation of Pasture at San Angelo, Texas       7-29
7-12   Muskegon Project Land  Treatment Site Plan                     7-34
7-13   Center Pivot Boom With Low Pressure Nozzle, Muskegon
        Project                                                      7-35
7-14   Installation of Drainage Tiles, Muskegon Project              7-37
7-15   Layout of the 23rd Avenue Rapid Infiltration and Recovery
        Project                                                      7-47
7-16   Inlet Structure, 23rd  Avenue Project, Phoenix, Arizona        7-48
7-17   Schematic of the 23rd  Avenue Rapid Infiltration and
        Recovery System                                              7-50
7-18   Rapid Infiltration Basin, Lake George, New York               7-55
7-19   Operational Basin Covered With Ice, Lake George,
        New York                                                     7-55
7-20   Lake George Village Wastewater Treatment Plant and
        Sampling Locations                                           7-56
                                   IX

-------
                           FIGURES (Continued)

No.

7-21   Land Treatment System, Fort Devens, Massachusetts             7-63
7-22   Distribution Channel Into Rapid Infiltration Basin,
        Fort Devens, Massachusetts                                   7-64
7-23   Grass Covered Infiltration Basins, Fort  Devens,
        Massachusetts                                                7-64
7-24   Fixed Fan Nozzle, Pauls Valley, Oklahoma                      7-69
7-25   Bubbling Orifice for Wastewater Application, Pauls Valley,
        Oklahoma                                                     7-70
7-26   Overland Flow Terraces at Paris, Texas                        7-75
8-1    General Topography                                            8-5
8-2    Agricultural Soil Map                                         8-6
8-3    Existing Vegetative Cover                                     8-9
A-l    Nitrate in Effluent From a Column of Salado Subsoil
        Receiving 3 in./wk of Wastewater Containing 42 mg/L
        NH|-N, Showing High-Nitrate Wave                             A-4
A-2    Effect of Input NHJ-N Concentration on N Removal From
        Wastewater Applied to Panoche Sandy Loam at the Rate
        of 3 in./wk for 6 Months                                     A-l3
A-3    Yield, Crop Uptake of N, and Potentially Leachable
        Nitrate in Relation to Fertilizer Application Rate on
        Corn Grown on Hanford Sandy Loam      •                       A-16
A-4    Clay Fixed NHt in Three Soils Resulting  From Five
        Applications of a Solution Containing 100 mg/L NH^-N,
        Without Intervening Drying                                   A-l8
A-5    Exchangeable NH^ in the Profile of a Sandy Soil Beneath
        a Sludge Pond as Compared to an Untreaited Area               A-20
A-6    Effect of 36 Years of Wastewater Application on
        Organic N in a Soil at Bakersfield, California               A-22
B-l    Relationships Between Phosphorus Concentration and Soil
        Depth for Abrupt and Diffuse Boundaries Between
        Enriched and Nonenriched Soil                                B-4
B-2    Net Phosphorus Application to the Soil                        B-l2
B-3    Relationship Among Phosphorus Concentration, Drainage
        Flow, and the Amount of Phosphorus Transfer From
        Land to Streams                                              B-14
B-4    Illustration of a Simple Phosphorus Balance -
        Phosphorus Reaction Model for a Slow Rate System             B-24
C-l    Soil-Water Characteristic Curves for Several Soils            C-3
C-2    Field Capacity Relationship                                   C-4
C-3    Schematic Showing Relationship of Total  Head (H),
        Pressure Head (h), and Gravitation Head (Z) for
        Saturation Flow                                              C-7
C-4    Permeability as a Function of the Matric Potential
        for Several Soils                                            C-9
C-5    Infiltration Rate as a Function of Time  for
        Several Soils                                                C-10
C-6    Porosity, Specific Retention, and Specific Yield
        Variations with Grains Size, South Coastal Basin,
        California                                                   C-ll

-------
                          FIGURES (Concluded)

No.                                                                  Page

C-7    Infiltration Rate Curves Showing the Influence of Initial
        Water Content, 0 (Fraction by Volume), on Infiltration
        Rate Computed for Yolo Light Clay                            C-13
C-8    Cumulative Intake Curves Showing the Infiltration of
        Water Into.Soil From Single Ring Infiltrometers              C-15
C-9    Typical Pattern of the Changing Moisture Profile
        During Drying and Drainage                                   C-16
C-10   Flooding Basin Used for Measuring Infiltration                C-20
C-ll   Layout of Sprinkler Infiltrometer                             C-21
C-12   Cylinder Infiltrometer in Use                                 C-23
C-13   Variability of Infiltrometer Test Results on
        Relatively Homogeneous Site                                  C-26
C-14   Number of Tests Required for 90% Confidence That the
        Calculated Mean is Within Stated Percent of the True Mean    C-28
C-15   Number of Tests Required for 95% Confidence That the
        Calculated Mean is Within Stated Percent of the True Mean    C-28
C-16   Lysimeter Cross-Section                                       C-29
C-17   Mound Development for Strip Recharge                          C-36
C-18   Mound Development for Circular Recharge Area                  C-36
C-19   Definition Sketch for Auger-Hole Technique                    C-41
C-20   Experimental Setup for Auger-Hole Technique                   C-41
C-21   Definition Sketch for Drain Spacing Formula                   C-45
D-l    Virus Adsorption by Various Soils as a Function of pH         D-16
E-l    Patterns of Distribution of Trace Elements With
        Depth in Soil Profiles                                       E-9
E-2    Effect of pH on Adsorption of Metal by Oxides
        and Silicates                                                E-16
E-3    Typical Adsorption Isotherm for Metal Salt Addition
        to a Soil- or Sediment-Water System                          E-17
E-4    Schematic Response of a Typical Plant Species to
        Increasing Zinc Addition to a Soil                           E-21
E-5    Calculated Accumulation of Cadmium in Soil at
        Constant Annual Input      •                                  E-26
E-6    Log-Log Plot of Dry Matter Production of Sweet Corn as
        a Function of Zinc (Zinc Acetate) Additions to Soil          E-29
F-l    Nomograph for Determining the SAR Value of Irrigation
        Water and For Estimating the Corresponding ESP Value
        of a Soil That is at Equilibrium with the Water              F-15

-------
                                 TABLES

No.                                                                  Page

1-1    Selected Early Land Application Systems                       1-2
1-2    U.S. Municipalities Using Land Treatment                      1-2
2-1    Comparison of Design Features for Land Treatment Processes    2-2
2-2    Comparison of Site Characteristics for Land
        Treatment Processes                                          2-3
2-3    Expected Quality of Treated Water from Land
        Treatment Processes                                          2-4
2-4    Treatment Performance for Two Artificial Wetland
        Systems on Long Island                                       2-15
2-5    Treatment Capability of Water Hyacinths Fed
        Oxidation Pond Effluent                                      2-16
2-6    Treatment Performance of Peatland in Minnesota                2-17
2-7    Treatment Performance of an Experimental Soil
        Mound System in Wisconsin                                    2-19
3-1    Applicability of Recovery Systems for
        Renovated Water                                              3-14
3-2    Important Constituents in Typical Domestic Wastewater         3-14
3-3    Typical BOD Loading Rates                                     3-15
3-4    Concentration of Trace Elements in Various U.S.
        Wastewaters                                                  3-16
3-5    Site Selection Guidelines                                     3-18
3-6    Soil Textural Classes and General Terminology  Used
        in Soil Descriptions                                         3-23
3-7    Permeability Classes for Saturated Soil                       3-24
3-8    Typical Soil Permeabilities and Textural Classes
        for Land Treatment Processes                                 3-24
3-9    Summary of Climatic Analyses                                  3-27
3-10   Average Values of Nitrogen and Phosphorus Measured in
        Agricultural Stormwater Runoff Studies                       3-29
3-11   Summary of Agricultural Nonpoint Sources Characteristics      3-30
3-12   Potential Water Rights Problems for Land
        Treatment Alternatives                                       3-34
3-13   Checklist of Capital Costs for Alternative
        Land Treatment Systems                                       3-46
3-14   Suggested Service Life for Components of an
        Irrigation System                                            3-47
3-15   Checklist of Annual Operation and Maintenance  Costs
        for Alternative Land Treatment Systems                       3-49
3-16   Requirements for Land Leasing for PL 92-500
        Grant Funding                                                3-51
3-17   Cost Tradeoff Considerations for Land Treatment Systems       3-53
3-18   Nonmonetary Factors for Evaluation of Alternatives            3-53
3-19   Comparison of Effluent Quality for Conventional, Land
        Treatment,.and Advanced Wastewater Treatment  Systems         3-55
4-1    Summary of Field Tests for Land Treatment Processes           4-1
4-2    Relationship of Potential Problems to Concentrations of
        Major Inorganic Constituents in Irrigation Waters
        for Arid and Semi arid Climates                               4-3
4-3    Interpretation of Soil Physical and Hydraulic  Properties      4-4
                                   xn

-------
                         TABLES (Continued)

No.                                                                  Page

4-4    Interpreptation of Soil Chemical Tests                        4-5
4-5    Probable Soil Characteristics Indicated by Plants    .         4-9
5-1    EPA-Proposed Regulations on Interim Primary
        Drinking Water Standards, 1975                               5-3
5-2    Typical Values of Crop Uptake of Nitrogen                     5-6
5-3    Factors Favoring Denitrification in the Soil                   5-7
5-4    Suggested Maximum Applications of Trace Elements
        to Soils Without Further Investigation                       5-10
5-5    Typical Hydraulic Loading Rates for RI Systems                5-12
5-6    Typical Hydrualic Loading Cycles                              5-13
5-7    BOD and Suspended Solids Data for Selected Rapid
        Infiltration Systems                                         5-16
5-8    Fecal Coliform Removal in Selected Rapid
        Infiltration Systems                                         5-17
5-9    Selected Hydraulic Loading Rates for Overland Flow Systems    5-19
5-10   Nitrogen Concentrations in Treated Runoff From Overland
        Flow When Using Untreated Wastewater                         5-20
5-11   Phosphorus Concentrations in Treated Runoff From
        Overland Flow, Ada, Oklahoma                                 5-21
5-12   Hydraulic Loadings and General Performance Criteria -
        Research and Demonstration Wetland Systems                   5-22
5-13   Need for Preapplication Treatment                             5-27
5-14   Summary of Computer Programs for Determining Storage
        From Climatic Variables                                      5-31
5-15   Threshold Values for the EPA-1 Storage Program                5-33
5-16   Example of Storage Determination From a Water Balance
        for Irrigation                                               5-36
5-17   Irrigation and Consumptive Use Requirements for Selected
        Crops at Bakersfield, California                             5-37
5-18   Surface Irrigation Methods and Conditions of Use              5-41
5-19   Nonirrigating Surface Application Methods and
        Conditions of Use                                            5-43
5-20   Suggested Maximum Lengths of Cultivated Furrows for
        Different Soils, Slopes, and Depths of Water to be Applied   5-44
5-21   Optimum Furrow or Corrugation Spacing                         5-44
5-22   Recommended Maximum Border Strip Width                        5-47
5-23   Design Standards for Border Strip Irrigation, Deep
        Rooted Crops                                                 5-47
5-24   Design Standards for Border Strip Irrigation, Shallow
        Rooted Crops                                                 5-48
5-25   Discharge Capacities of Surface Gated Pipe Outlets            5-56
5-26   Sprinkler System Characteristics                              5-59
5-27   Classification of Sprinklers and Their Adaptability           5-68
5-28   Factor (F) by Which Pipe Friction Loss is Multiplied to
        Obtain Actual Loss in a Line with Multiple Outlets           5-70
5-29   Depth and Spacing of Underdrains for Slow Rate Systems         5-72
5-30   Recommended ASAE Runoff Design Factors for Surface
        Flood Distribution                                           5-75
5-31   Peak Consumptive Water Use and Rooting Depth                  5-80
                                  xm

-------
                          TABLES (Continued)

No.                                                                  Page

5-32   Nutrient Uptake Rates for Selected Crops                      5-82
5-33   Electrical Conductivity Values Resulting in Reductions
        in Crop Yield                                                5-85
5-34   Crop Boron Tolerance                                          5-86
5-35   Crop Acidity Tolerance                                        5-86
5-36   Evapotranspiration of Woodland and Forest Crops               5-88
5-37   Recommended Irrigation Rates of Forest Crops                  5-89
5-38   Effect of Lime on Element Availability in Soil                5-91
5-39   Example Monitoring Program for a Large Slow Rate System       5-95
5-40   A Comparison of Chemicals to Gypsum                           5-98
5-41   Allowable Soil Contact Pressure                               5-101
6-1    Types and Sources of Data Required for Land
        Treatment Designs                                            6-2
6-2    Important Components of Domestic Wastewater                   6-4
6-3    Design Unit Wastewater Flows for Recreational  Facilities,
        Yellowstone National Park                                    6-5
6-4    Average Wastewater Flows from Institutional Facilities        6-5
6-5    Total Land Area Guidelines for Preliminary
        Site Identification                                          6-6
6-6    Preliminary Selection of Land Treatment Systems               6-8
6-7    Summary of Application Periods for Land Treatment Systems     6-9
6-8    Design Application Rates for Small Systems                    6-9
6-9    Minimum Preapplication Treatment Practice                     6-13
6-10   Guidelines for Storage Volumes                                6-13
6-11   Factors Affecting the Design of Surface Irrigation Systems    6-16
6-12   Factors Affecting the Design of Sprinkler
        Irrigation Systems                                           6-18
6-13   Potential Land Treatment Sites for Angus, Washington          6-24
6-14   Required Acreages for Angus Land Treatment Systems            6-25
6-15   Land Treatment Alternatives for Angus, Washington             6-27
6-16   Summary of Feasible Land Treatment Systems for
        Angus, Washington                                            6-29
7-1    Summary of Case Studies                                       7-1
7-2    Design Factors, Pleasanton, California                        7-3
7-3    Characteristics of Holding Pond Effluent and Groundwater
        Quality, Pleasanton, California                              7-7
7-4    Trace Wastewater Constituents of Holding Pond Effluent,
        Pleasanton, California, September 1975                       7-8
7-5    Approximate Operation and Maintenance Costs, Land
        Treatment System, Pleasanton, California                     7-9
7-6    Design Factors, Walla Walla, Washington                       7-11
7-7    Average Daily Flow of Wastewater, Walla Walla, Washington     7-14
7-8    Average Estimated Operations Costs, Walla Walla, Washington   7-18
7-9    Design Factors, Bakersfield, California                       7-19
7-10   Composite Wastewater Characteristics for City Plants Nos. 1
        and 2, Bakersfield, California                               7-22
7-11   Loading Rates in 1973 and Typical Nitrogen Uptake
        Requirements, Bakersfield Land Treatment System              7-22
7-12   Existing Crop Yields and Economic Return, Bakersfield
        Land Treatment System                                        7-23
                                   xiv

-------
                           TABLES (Continued)

No.                                                                  Page

7-13   Estimated Construction Costs, Proposed  Wastewater
        Irrigation System, Bakersfield, California                   7-26
7-14   Design Factors, San Agnelo, Texas                 .            7-27
7-15   Treatment Performance, San Angelo, Texas                      7-30
7-16   Sample of Groundwater Quality, San Angelo, Texas              7-31
7-17   Design Factors, Muskegon Project, Muskegon, Michigan          7-33
7-18   Distribution System Data, Muskegon Project                    7-36
7-19   Representative Yields of Corn Grain, for Various Soil
        Types, Muskegon Land Treatment Site, 1975                    7-38
7-20   Increased Agricultural Productivity, Muskegon Land
        Treatment Site                                               7-39
7-21   Summary of Treatment Performance, 1975  Average
        Results, Muskegon Project                                    7-40
7-22   Operating Costs, Muskegon Wastewater System, 1975             7-41
7-23   Design Factors, St. Charles, Maryland                         7-42
7-24   Design Factors, Phoenix, Arizona                              7-45
7-25   Renovated Water Quality, The 23rd Avenue Project in
        Phoenix, Arizona                                             7-49
7-26   Characteristics of System Influent and  Renovated
        Water, Flushing Meadows, Phoenix, Arizona                    7-52
7-27   Design Factors, Lake George, New York                         7-54
7-28   Water Quality Data, Seasonal Means, Lake George, New York     7-59
7-29   Design Factors, Fort Devens, Massachusetts                    7-61
7-30   Chemical and Bacteriological Characteristics of Primary
        Effluent and Groundwater in Selected Observation Wells,
        Fort Devens Land Treatment Site                              7-66
7-31   Design Factors, Pauls Valley, Oklahoma                         7-68
7-32   Unit Costs of Overland Flow Application, Pauls
        Valley, Oklahoma                       .                      7-71
7-33   Design Factors, Paris, Texas                                  7-72
7-34   Treatment Performance During 1968 Compared to Effluent
        Quality in 1976, Paris, Texas                                7-73
7-35   Seasonal Quality of Treated Effluent, Paris, Texas            7-74
7-36   Construction and Operating Costs, Paris, Texas,                7-75
8-1    Climatic Data for the Worst Year in 10                         8-2
8-2    Water Quality Characteristics                                 8-3
8-3    Available Land Areas by Soil Type                             8-7
8-4    Determination of Overland Flow Application Schedule
        Based on Climatic Data                                       8-11
8-5    Summary of Design Information for Treatment Alternatives       8-15
8-6    Relative Cost Comparisons, Design Example Alternatives        8-16
8-7    Monthly Design Nitrogen Balance, Slow Rate System             8-20
8-8    Trace Metals in Slow Rate Design Example                      8-22
8-9    Design Factors, Slow Rate Treatment with
        Center Pivot Distribution                                    8-24
A-l    Nitrogen Uptake Efficiencies of Corn in Relation to
        Quantities of Nitrogen and Water Applied                     A-10
A-2    Three Year Balance Sheet for Isotopically Labelled Nitrogen
        Fertilizer Applied tc Corn Plots on Hanford Sandy Loam       A-l2
                                  xv

-------
                           TABLES (Continued)

No.                                                                  Page

A-3    Nitrate-N Concentrations in Soil  Solution Samples Obtained
        by Means of Suction Probes at Four Depths on Two Dates
        in a Corn Field on Yolo Fine Sandy Loam                      A-17
A-4    Recovery of Total and Tagged N in Effluent From Three
        Soils Receiving l^N-Labelled Wastewater at the
        Rate of 3 in./wk                                             A-23
B-l    Removal of Phosphorus by the Usual  Harvested Portion
        of Selected Crops                                            B-5
C-l    Relation of Saturation Percentage to Soil Texture             C-6
C-2    Comparison of Infiltration Measurement  Using Flooding
        and Sprinkling Techniques                                    C-18
C-3    Comparison of Infiltration Measurement  Using Standard
        USPHS Percolation Test and Double-Cylinder Infiltrometer     C-19
C-4    Subsurface Logging Information Obtained by Various Methods    C-34
C-5    Approximate Drainable Voids for Major Soil Classifications    C-38
C-6    Statistical Variability of Several  Physical
        Properties of Soil                                           C-39
C-7    Measured Ratios of Horizontal to Vertical Permeability        C-40
C-8    Summary of Measured Infiltration Rates  and Operating
        Rates for Selected Land Application Systems                  C-46
D-l    Estimated Concentrations of Wastewater Pathogens              D-4
D-2    Factors That Affect the Survival  of Enteric Bacteria
        and Viruses in Soil                                          D-8
D-3    Factors That Influence the Movement of  Viruses in Soil        D-l9
D-4    Factors That Affect the Survival  and Dispersion of
        Bacteria and Viruses in Wastewater Aerosols                  D-23
E-l    Classification of Substances with Which Metals May Form
        Chemical and/or Physical  Associations  in Fresh Waters
        and Wastewaters                                              E-3
E-2    Average and Ranges of Soil Concentrations of
        Selected Elements                                            E-7
E-3    Classification of States of Metals  in Soils                   E-ll
E-4    Assumptions and Selected Performance Values Used to
        Calculate Crop Removal Coefficients k2 and Yearly
        Application of Metal in Wastewater k]  for Evaluation
        of Cadmium                                                   E-24
E-5    Concentration of Zinc in Plant Tissues  and Interpolated
        Applied Zinc Concentration in Soil at  the 20% Yield
        Decrement                                                    E-32
F-l    Types of Data Needed for Various Evapotranspiration
        Predicition Methods                                          F-2
F-2    Typical Properties Determined When  Formulating Soil Maps      F-6
F-3    Effects of Various pH Ranges on Crops                         F-ll
F-4    Typical Ranges of Cation Exchange Capacity of Various
        Types of Soils                                               F-l3
F-5    Satisfactory Balance of Exchangeable Cations Occupying
        the Cation Exchange Capacity                                 F-13
F-6    Factors for Computing the Adjusted  SAR                        F-16
                                    xvi

-------
                          TABLES (Concluded)

No.                                                                  Page

F-7    Salinity Levels at Which Crop Growth is Restricted            F-17
F-8    Approximate Critical Levels of Nutrients for Selected
        Crops in California                                          F-19
F-9    Critical Phytotoxic Levels of Boron in Soils                  F-20
                                   xvn

-------
                                 FOREWORD
Land   treatment   is  a  reliable  engineering   process   for  wastewater
management.   Land  application  of  wastewaters   has been practiced  in  a
number  of modes, including crop and landscape  irrigation; as a treatment
process  with  collection  and  discharge   of   treated water; as indirect
discharge  to  surface  water; and as application to the  soil surface for
groundwater  recharge.   It  is  possible  to modify any of these modes to
meet project objectives, including the combination of several in a single
management system.

The  benefits  of  land  treatment systems can  go beyond  the treatment of
wastewater.  Land treatment processes involve the recovery and beneficial
reuse   of   wastewater   nutrients   and   other   elements  through  good
agriculture,  silviculture,  and  aquaculture practices.   These practices
permit the achievement of advanced levels  of wastewater treatment as  well
as   water   reclamation  and  resource  recovery  objectives  of  recent
environmental  legislation.   The production of revenues  through the  sale
of  byproducts (e.g., crops) can be realized.  Land treatment systems can
aid  in  the  reclamation  and  reuse  of   water   resources,  recharge of
groundwater  aquifers, reclamation of marginal  land, and  the preservation
of open spaces for future greenbelts.

It is the purpose of this manual to describe the  basic principles of  land
treatment  and  to  present  a  rational   procedure  for   design  of  land
treatment  systems.   Information contained in  this manual can be used in
identifying   alternatives   during  planning,  in  selecting  a  process
alternative  or  site, in determining necessary field investigations, and
in conducting the process design.

This  manual  is  unique in the Technology Transfer Process Design Manual
series  because  its  preparation  was  jointly   sponsored  by  the U. S.
Environmental  Protection  Agency  (EPA)   and   the  U.S.   Army  Corps  of
Engineers.   The U.S. Department of Agriculture (USDA) provided technical
assistance   during   the  review   process.    In  recognition  of  these
contributions, the cover and title page were designed to  clearly indicate
the  endorsement  of  these  three agencies.  The review  process included
over  thirty individuals contributing significantly to the preparation of
this  manual.   They  provided  a  broad range  of technical expertise and
represented  a wide variety of agencies and institutions.   This extensive
review ensured the accuracy and the authority of  the product.

The  manual  represents  the  current  state-of-the-art  with  respect to
criteria, data, and procedures for the design of  land treatment processes
for  municipal  wastewaters.   Much of the information is also applicable
for  design  of  systems  managing industrial wastewaters.  Revisions and
improvements  will  be made as results of  current and future research and
development become available.
                                  xvm

-------
                                CHAPTER 1

                              INTRODUCTION
1.1  Background and History


Land  treatment  of municipal wastewater involves the use of plants,  the
soil  surface,  and  the  soil  matrix to remove many wastewater  consti-
tuents. A  wide variety of processes can be used to achieve many  differ-
ent objectives  of  treatment, water reuse, nutrient recycling, and crop
production.
The  concept  of  land application of wastewater certainly  is  not  new  to
the  field of sanitary engineering.  Evidence of such systems  in western
civilization  extends  back  as far as ancient Athens [1].   A  wastewater
irrigation system in Bunzlaw, Germany, is reported to have  been  in oper-
ation for over 300 years beginning in 1559 [2].
The  greatest proliferation of land treatment systems occurred in Europe
in  the second half of the nineteenth century.   Pollution of many rivers
had  reached unacceptable levels, and disposal  of sewage on the land was
the  only  feasible  means  of treatment available at the time. "Sewage
farming," the practice of transporting sewage into rural areas for  irri-
gation and  disposal,  was commonly used by many European cities, inclu-
ding some  of  those shown in Table 1-1.  In the 1870s,  the practice was
recognized  in  England as treatment, with many underdrained systems ex-
hibiting sparkling clear effluents [3].   As urban areas  expanded and in-
plant treatment  processes became available, many of these older systems
were abandoned because of land development pressures.


Early  experiences in the United States  also date back to the 1870s [4].
As in Europe, sewage farming became relatively  common as a first attempt
to control water pollution.  In the first half  of the twentieth century,
these early systems were generally replaced either by in-plant treatment
or by  (1)  managed  farms  where  treated  wastewater was used for crop
production,  (2) landscape irrigation sites, or (3)  groundwater recharge
sites [1].  These  newer land treatment  systems tended to predominate  in
the  West where the resource value of wastewater was an  added advantage.
In  addition,  experience  with  land application of food processing and
pulp  and paper industrial wastewaters has been drawn upon in developing
the technology of land treatment [1, 5].
The  increasing use of land treatment over the last 40 years  is shown  in
Table  1-2,  which  was  compiled from periodic inventories of municipal
wastewater  treatment  facilities  [2].   While  it  is evident that  the
number  of  systems has steadily grown, it still  represents only a  small
percentage  of the estimated 15 000 total  municipal  treatment facilities
[2].
                                  1-1

-------
                       TABLE 1-1

      SELECTED EARLY  LAND APPLICATION SYSTEMS
                 [1, 2,  5, 6, 7,  8]
Location
International
Croydon-Beddington, England
Paris, France
Leamington, England
Berlin, Germany
Wroclaw, Poland
Melbourne, Australia
Braunschweig, Germany
Mexico City, Mexico
United States
Calumet City, Michigan
Woodland, California
Fresno, California
San Antonio, Texas
Vineland, New Jersey
Ely, Nevada
Date
started

1860
1869
1870
1874
1882
1893
1896
1900

1888
1889
1891
1895
1901
1908
Type of
system

Sewage farm
SRa
Sewage farm
Sewage farm
Sewage farm
SR
OFb
Sewage farm
SR

RIC
SR
SR
SR
RI
SR
Area,
acres

630
16 000
400
68 000
2 000
10 400
3 500
11 000
112 000

12
240
4 000
4 000
14
1 400
Flow,
Mgal/d

5.6
79
1
28
50
70
16
570

1.2
4.2
26
20
0.8
1.5
a.  SR = slow rate.
b.  OF = overland flow.
c.  RI = rapid infiltration.

1 acre = 0.405 ha
1 Mgal/d = 43.8 L/s
                       TABLE 1-2

                  U.S.  MUNICIPALITIES
              USING LAND TREATMENT [2]
Year
1940
1945
1957
1962
1968
1972
No. of
systems
304
422
461
401
512
571
Population
served, millions
0.9
1.3
2.0
2.7
4.2
6.6
                         1-2

-------
In recent years, much effort has been spent on developing  land  treatment
technology  and improving methods of control.   The various types  of  land
treatment  systems  have become accepted as viable wastewater management
techniques that should be considered equally with any others.  The regu-
lations developed  pursuant  to  the Federal Water Pollution  Control Act
Amendments  of  1972 (Public Law 92-500) require that such consideration
be  given  for  federally  funded municipal wastewater projects.   In the
Act,  the  Environmental  Protection Agency administrator  is  directed to
encourage  waste  treatment  management  that  results in  facilities for
(1)  the  recycling  of  potential  pollutants through the production of
agricultural,   silvicultural,    and   aquacultural   products;   (2)  the
reclamation  of  wastewater; and (3) the elimination of the discharge of
pollutants.
1.2  Objectives
The  primary  objective  of  this  manual   is to provide a comprehensive
source  of  information  to  be  used in the planning and design  of  land
treatment  systems.   It  is  not  intended  to serve as a definition  of
policy on land treatment, but rather to set forth and extend the  present
state-of-the-art  technology.  Recommended procedures, case studies, and
several  examples  are presented which are intended to serve as planning
and design aids.


Throughout  the  manual,  emphasis  is given to the wide range of design
possibilities  available  for  land  treatment  systems.   The  user  is
encouraged  to  adapt  the  techniques  and procedures described  to  suit
local needs and conditions.
1.3  Scope of the Manual


Planning  and  technical  information  for  each  of the following  major
wastewater treatment processes involving land application are presented:

     •    Slow rate (SR), also referred to as^crop irrigation
     •    Rapid infiltration (RI)
     •    Overland flow (OF)
Other  types  of  systems, such as wetland and subsurface systems,  which
are  uncommon  or  new,  are also described but in less detail.   Systems
specifically  involving the land application of sludge, injection wells,
sealed  evaporation ponds, and conventional septic tank leach fields  are
not covered.
The  scope  of  most  of  the  information  in the manual  is directed to
medium-to-large systems.  For small.systems, say 0.1 million gallons  per
                                  1-3

-------
day  (Mgal/d) [4.4 L/s], or less, many of the design procedures presented
in   the manual must be realistically simplified.   Special  considerations
for  small systems are discussed separately in Chapter 6.


To  minimize the amount of theoretical  and background information in the
manual,  papers  on  six  topics  of  special   interest  are included as
appendixes.   These  papers  were written by recognized experts in their
particular   fields  and  cover  the  following  topics:   (1)   nitrogen,
(2)  phosphorus,  (3) hydraulic capacity, (4)  pathogens,  (5) metals, and
(6) field investigation procedures.  These appendixes form the technical
foundation  for  the  body  of the report.  Research results reported in
this manual are current through 1976.     Detailed  procedures  for deter-
mining  capital and operation and maintenance costs are not included  in
this manual.  Sources for such information are  given in  Chapter 3 along
with general summaries.
1.4  Guide to Intended Use
The  contents  of the manual  should be  helpful  to  a  variety of different
users,  including  those  seeking  to gain  a general  perspective  on  land
treatment  and  those  looking  for specific design  information.  Conse-
quently, the  manual  is organized to allow  the  user  to  locate particular
information  and  to concentrate on specific areas of interest as easily
as  possible.  Subject, location, and author indexes are  provided to al-
low easy access to specific information.  A glossary is also provided to
give  definitions  of terms germane to  land treatment which might not be
familiar  to  the  traditional  civil/sanitary   engineer.  The following
brief chapter descriptions are provided as  an introduction to the organ-
ization of the manual.
Chapter 2 - Treatment Process Capabilities  and  Objectives.
The  basic  concepts  of  each  process of  land treatment are  described.
Standard  terminology  and  ranges of important design  criteria  that  are
encountered throughout the rest of the manual are presented.
Chapter 3 - Technical Planning and Feasibility  Assessment.
Information  for  those  users  involved in  both  regional  and facilities
planning  efforts  is  provided.    Most of the  technical  information  and
guidance  contained  in  the  manual  is presented here and in Chapter 5.
Procedures  are described for investigating  sites and for developing  and
evaluating  land  treatment  alternatives.   Wherever possible,  desirable
ranges  of criteria associated with physical  characteristics  are given.
Chapter 4 - Field Investigations.
Field  investigations  are  outlined  for  each   land treatment process.
Reasons for field tests are given  along with guidance on possible inter-
pretation of test results.
                                   1-4

-------
Chapter 5 - Process Design.
Design guidelines  are  presented   for   projects   in  which the site and
process  have been determined.  In  the first part  of the chapter, each of
the  major  treatment processes  is discussed separately  with  respect to
application rates and removals  of  various  wastewater  constituents.  Sub-
sequent  sections  are  devoted to design   components of land treatment
systems.  These include preapplication  treatment, storage,  distribution,
and  management of renovated water. Discussions  are  then provided on
vegetation and agricultural  management,  system  monitoring, and facili-
ties design guidance.
Chapter 6 - Small  Systems.
Simplified designs  that  are  possible   for small  community  systems are
described.   Shortcuts  for the planning  and design procedures described
in  Chapters 3 and 5 are given  along with  special   considerations.  A
design example is also included.

Chapter 7 - Case Studies.
Brief descriptions  of  the design criteria and operational  characteris-
tics of 11 successful  land treatment systems are presented.   The  systems
were  chosen to represent as broad a cross-section  as  possible with res-
pect to type of system, size, and location.


Chapter 8 - Design Example.
An example that illustrates the principles described in Chapters  3 and 5
is presented.  For a flow of 10 Mgal/d  (0.44 m3/s),  in a humid  eastern
climate,  alternatives  are  developed  and compared for slow rate and a
combination of the overland flow and rapid infiltration processes.
1.5  References

1.   Pound,  C.E.  and  R.W.   Crites.   Wastewater Treatment  and  Reuse by
     Land  Application.    Volumes  I   and  II.   Environmental  Protection
     Agency, Office of Research and Development.   August 1973.

2.   Thomas.  R.E.   Land Disposal II:   An Overview of  Treatment  Methods.
     Jour. WPCF 45:1476-1484.   July 1973.

3.   Kirkwood,  J.P.   The  Pollution   of  River Waters.  Seventh Annual
     Report  of  the  Massachusetts State  Board  of   Health.   Wright &
     Potter, Boston.  1876.   Reprint Edition 1970 by Arno Press  Inc.

4.   Rafter,  G.W.    Sewage   Irrigation,  Part II.   USGS  Water Supply and
     Irrigation.  Paper No.  22.  1899.

5.   Sullivan, R.H., et al.   Survey of  Facilities Using  Land Application
     of  Wastewater.   Environmental   Protection Agency,  Office  of Water
     Program Operations.  EPA-430/9-73-006.   July 1973.
                                  1-5

-------
6.   Hartman,  W.J.   Jr.    An  Evaluation  of Land Treatment of Municipal
     Wastewater  and  Physical  Siting  of Facility Installations.  May
     1975.

7.   Baillod,  C.R.,  et  al.  Preliminary Evaluation of 88 Years Rapid
     Infiltration   of   Raw   Municipal   Sewage  at  Calumet, Michigan.
     (Presented  at  the 8th Annual Cornell Waste Management Conference.
     Rochester.  April 1976.)

8.   Bocko,  J.  and J.  Paluch.   The Effect of  Irrigation with Municipal
     Sewage  on  the  Sanitary  Condition of Ground Waters.  Zesz.  Nauk.
     (Poland) WSR Wroclaw, Melioracja:  14(90):49-59.  1970.
                                  1-6

-------
                                CHAPTER 2

              TREATMENT PROCESS CAPABILITIES AND OBJECTIVES


2.1  Introduction


Land  treatment  of  municipal  wastewater encompasses a wide variety  of
processes  or methods.  The three principal  processes, as referred to  in
this manual, are:

     1.   Slow rate

     2.   Rapid infiltration

     3.   Overland flow
Other processes, which are less widely used and generally less adaptable
to large-scale use than the three principal ones,  include:

     1.   Wetlands

     2.   Subsurface


The  major  concepts  involved in these processes  are introduced  in  this
chapter.   Descriptions  are  given  of  system objectives  and treatment
mechanisms.
Typical  design  features  for  the various land treatment processes  are
compared  in  Table 2-1,  with  more  detail  provided in Chapter 5.   The
major  site characteristics are compared for each process in Table   2-2,
with more detail provided in Chapter 3.   The expected quality of treated
water  from  the  three  principal   land treatment processes is  shown in
Table  2-3.    The  major  removal  mechanisms responsible for the quality
improvement are described for each land  treatment process in the follow-
ing sections.
2.2  Slow Rate Process
In  several  previous EPA reports, including Evaluation of Land Applica-
tion Systems  [1],  slow  rate land treatment was referred to as irriga-
tion.  The  term  slow rate land treatment is used to focus attention  on
wastewater  treatment  rather  than on irrigation of crops.  However,  in
slow rate systems, vegetation is a critical  component for managing water
and nutrients.
                                  2-1

-------
                                                                        TABLE  2-1
                                         COMPARISON OF DESIGN FEATURES FOR LAND  TREATMENT PROCESSES
ro
i
ro
Feature
Application techniques
Annual application
rate, ft
Field area required,
acresb
Typical weekly appli-
cation rate, in.
Minimum preappli cation
treatment provided
in United States
Disposition of
applied wastewater
Need for vegetation

Slow rate
Sprinkler or
surface9
2 to 20
56 to 560
0.5 to 4
Primary
sedimentation^
Evapotranspi ration
and percolation
Required
Principal processes
Rapid Infiltration
Usually surface
20 to 560
2 to 56
4 to 120
Primary
sedimentation
Mainly
percolation
Optional
Other processes
Overland flow
Sprinkler, or
surface
10 to 70
16 to 110
2.5 to 6C
6 to 16d
Screening and
grit removal
Surface runoff and
evapotranspi rati on
with some
percolation
Required
Wetlands
Sprinkler or
surface
4 to 100
11 to. 280
1 to 25
Primary
sedimentation
Evapotranspi ration ,
percolation,
and runoff
Required
Subsurface
Subsurface piping
8 to 87
13 to 140
2 to 20
Primary
sedimentation
Percolation
with some
evapotranspi ration
Optional
                     a.  Includes ridge-and-furrow and border strip.
                     b.  Field  area in acres  not including buffer area,  roads, or ditches for 1  Mgal/d (43.8 L/s) flow.
                     c.  Range  for application of screened wastewater.
                     d.  Range  for application of lagoon and secondary effluent.
                     e.  Depends on the use of the effluent and the type of crop.
                     1 in.  =  2.54 cm
                     1 ft = 0.305 m
                     1 acre" = 0.405 ha

-------
                                                           TABLE 2-2


                              COMPARISON OF  SITE  CHARACTERISTICS FOR LAND TREATMENT PROCESSES
PO
I
co
Characteristics
Slope
Soil permeability
Depth to
groundwater
Climatic
restrictions

Slow rate
Less than 20% on culti-
vated land; less than
40% on noncultivated
land
Moderately slow to
moderately rapid
2 to 3 ft (minimum)
Storage often needed
for cold weather and
precipitation
Principal processes
Rapid infiltration
Not critical; excessive
slopes require much
earthwork
Rapid (sands, loamy
sands)
10 ft (lesser depths
are acceptable where
underdrainage is
provided)
None (possibly modify
operation in cold -
weather)
Other processes
Overland flow
Finish slopes
2 to 8%
Slow (clays,
silts, and
soils with
impermeable
barriers)
Not critical
Storage often
needed for
cold weather
Wetlands
Usually less
than 5%
Slow to
moderate
Not critical
Storage may
be needed
for cold
weather
Subsurface
Not critical
Slow to rapid
Not critical
None
                   1 ft = 0.305 m

-------
                                TABLE 2-3

    EXPECTED QUALITY OF  TREATED WATER FROM LAND TREATMENT  PROCESSES
                                  mg/L
                            Slow rate3
   Rapid
infiltration15   Overland flowc
Constituent
BOD
Suspended solids
Ammonia nitrogen as N
Total nitrogen as N
Total phosphorus as P
Average
<2
<1
<0.5
3
<0.1
Maximum
<5
<5
<2
<8
<0.3
Average
2
2
0.5
10
1
Maximum
<5
<5
<2
<20
<5
Average
10
10
0.8
3
4
Maximum
<15
<20
<2
<5
<6
      a.  Percolation of primary or secondary effluent through 5 ft (1.5 m)
         of soil.
      b.  Percolation of primary or secondary effluent through 15 ft (4.5 m)
         of soil.

      c.  Runoff of comminuted municipal wastewater over about 150 ft (45 m)
         of slope.
The  applied  wastewater is treated as it flows  through  the soil  matrix,
and a portion of  the  flow percolates to the groundwater.   Surface runoff
of  the applied water is generally not allowed.  A  schematic view of the
typical  hydraulic  pathway for slow rate treatment  is  shown in Figure 2-
l(a).  Typical  views  of  slow  rate land treatment  systems, using both
surface and sprinkler application techniques, are   also   shown in Figure
2-1(b,  c).   Surface application includes  ridge-and-furrow  and border
strip  flooding techniques.  The term sprinkler  application is correctly
applied  to impact  sprinklers and the term spray application should only
be used to refer  to fixed spray heads.
The case  studies   in  Chapter  7 include six  slow rate systems that are
fairly  representative  of  those  found  throughout  the United States:
Pleasanton, California; Walla Walla,  Washington;   Bakersfield, Califor-
nia;  San  Angelo,  Texas;  Muskegon, Michigan;  and  St.  Charles, Maryland.
These  case studies provide an insight into actual  experiences with slow
rate systems.
                                   2-4

-------
         FIGURE  2-1



  SLOW RATE  LAND TREATMENT
                                EVAPOTRANSPIRATION
       PERCOLATION



 (a) HYDRAULIC  PATHWAY
(b) SURFACE DISTRIBUTION
  (c) SPRINKLER  DISTRIBUTION
               2-5

-------
     2.2.1   System Objectives
Slow  rate  systems  can  be  operated  to  achieve  a  number  of objectives
including:

     1.   Treatment of applied wastewater

     2.   Economic  return  from  use   of  water and  nutrients to produce
          marketable crops (irrigation)

     3.   Water  conservation,  by  replacing potable water with treated
          effluent,  for  irrigating landscaped   areas,  such  as  golf
          courses

     4.   Preservation and enlargement  of  greenbelts and open space
When requirements for surface discharge  are very  stringent  for  nitrogen,
phosphorus,  and  biochemical oxygen  demand (BOD),  they can be  met with
slow  rate  land  treatment.    If   the   percolating water  must meet EPA
drinking  water  standards,   reduction   in  nitrogen   below the 10 mg/L
standard  for nitrate-nitrogen is  often  the limiting criterion.  In arid
regions,  however,  increases  in  chlorides and toial  dissolved salts in
the  groundwater  may  be  limiting.   Management approaches to meet the
above  objectives  within  the slow rate process  are discussed  under the
topics   (1)   wastewater  treatment,  (2)  crop   irrigation,   (3)  turf
irrigation, and (4) silviculture.         ,         '
          2.2.1.1   Wastewater Treatment
When  the  primary  objective of  the  slow  rate process  is  treatment, the
hydraulic  loading  is limited either by the  infilration capacity of the
soil  or  the  nitrogen removal capacity of the  soil-vegetation complex.
If  the  hydraulic  capacity  of   the  site   is   limited by a  relatively
impermeable subsurface layer or by a  high  groundwater table, underdrains
can be installed to increase the  allowable loading.  Grasses are usually
chosen  for  the  vegetation  because  of  their  high  nitrogen  uptake
capacities.
          2.2.1.2  Crop Irrigation


When  the  crop  yields  and economic  returns  from  slow  rate  systems  are
emphasized,  crops  of  higher values  than  grasses  are usually  selected.
In the West, application rates are generally between  1 and  3  ip./wk  (2.5
to  7.6 cm/wk), which reflect the consumptive  use of  crops.   Consumptive
use  rates  are those required to replace the  water lost to evaporation,
plant  transpiration,  and stored in: plant  tissue,   in areas  where water
                                  2-6

-------
does  not  limit plant growth,  the nitrogen  and  phosphorus  in wastewater
can  be recycled in crops.   These nutrients  can  increase yields of corn,
grain sorghum, and similar  crops and provide an  economic return.


          2.2.1.3  Turf Irrigation
Golf  courses,  parks,  and  other  turfed  areas  can  be  irrigated with
wastewater,  thus,  conserving  potable   water   supplies.   These  areas
generally have considerable public access and this usually requires that
a disinfected effluent be applied.
          2.2.1.4.  Silviculture
Silviculture,  the  growing of trees,  is being  conducted with wastewater
effluent  in  at  least 11  existing sites in  Oregon,  Michigan, Maryland,
and  Florida  [2].   In  addition,   experimental  systems at  Pennsylvania
State  University [3], Michigan State  University  [4],  and  the University
of Washington [5] are being studied extensively to  determine permissible
loading  rates,  responses   of  various   tree species,  and environmental
effects.
Forests offer several  advantages as potential  sites  for  land  treatment:

     1.   Large forested areas exist near many sources of wastewater.

     2.   Forest soils often exhibit better infiltration properties than
          agricultural soils.

     3.   Site  acquisition  costs for forestland  are usually lower than
          site  acquisition costs for agricultural land  because of lower
          land values  for forestlands.

     4.   During  cold  weather,  soil  temperatures are often higher in
          forestlands  than in comparable agricultural lands.


The  principal limitations on the use of wastewater  for  silviculture are
that:

     1.   Water tolerances of the existing trees may be  low.

     2.   Nitrogen removals are relatively low.

     3.   Fixed sprinklers, which are expensive, must generally be used.
                                  2-7

-------
Existing   forests   are  adapted  to  the  water  supply   from   natural
precipitation.  Unless soils are well  drained,  the increase in hydraulic
loading  from  wastewater  application  will   drown  existing trees.   At
Seabrook  Farms,  New  Jersey,  the types of vegetation  have changed  from
predominantly  oak trees to wild berries, marsh grass,  and other grasses
[6].
     2.2.2  Treatment Performance
Slow  rate  treatment is generally capable  of  producing  the  best results
of  all the land treatment systems.   The  quality   values  shown  in  Table
2-3  can be  expected for most well-designed and  well-operated  slow rate
systems.
Organics  are  reduced substantially  by  slow  rate land treatment by  bio-
logical oxidation within the top few  inches of  soil.   At Muskegon, Mich-
igan, the  BOD  of  renovated water from the  drain tiles has  ranged  from
1.2  to  2.2 mg/L,  and  the  BOD  of renovated water intercepted by two
nearby  creeks  has  ranged from 2 to 3.3 mg/L  [7].   Preliminary results
for six test cells at a research project in Hanover,  New Hampshire,  show
average  annual  BOD concentrations in the percolate  ranging  from 0.6 to
2.1 mg/L [8].  These results were consistently  achieved with  application
rates  ranging up to 6 in./wk (15 cm/wk) with both primary  and secondary
effluents applied.  Filtration and adsorption are the initial  mechanisms
in  BOD  removal,  but  biological oxidation  is the ultimate treatment
mechanism.
Suspended  solids  removals  are not as well  documented as  BOD  removals,
but  concentrations  of  1  mg/L or less can generally be expected in  the
renovated  water.  Filtration is the major removal  mechanism for suspen-
ded solids.   Volatile  solids  are  biologically oxidized,  and fixed or
mineral solids become part of the soil  matrix.
Nitrogen is removed primarily by crop uptake,  which varies  with the  type
of  crop  grown and the crop yield.   To remove the nitrogen effectively,
the  portion  of  the crop that contains the nitrogen must  be  physically
removed  from  the field.  Denitrification can also be significant,  even
if  the  soil is in an aerobic condition most of the time.   In a labora-
tory study  using radioactive tracer materials, Broadbent reported deni-
trification losses  of  up  to  32%  of the applied nitrogen [9].  In the
test  cells at Hanover, denitrification losses were found to be 5 to 28%
[8].   In  both  of  these  cases,   the  soils  were  considered  to  be
essentially aerobic.
Phosphorus  is  removed from solution by fixation processes  in the soil,
such as adsorption and chemical  precipitation.   Removal  efficiencies  are
generally very high for slow rate systems and are usually more dependent
                                  2-8

-------
on the  soil  properties than on the concentration of the phosphorus  ap-
plied.  A small  but significant portion of the phosphorus applied (15 to
30% depending on the soil  and the crop) is taken up and removed with  the
crop.
2.3  Rapid Infiltration


In  rapid  infiltration  land treatment (referred to in previous EPA  re-
ports as  infiltration-percolation),  most of the applied wastewater per-
colates through  the  soil,  and the  treated effluent eventually reaches
the  groundwater.  The wastewater is  applied to rapidly permeable soils,
such  as sands and loamy sands, by spreading in basins or by sprinkling,
and is treated as it travels through  the soil  matrix.  Vegetation is  not
usually used, but there are some exceptions.


The  schematic  view  in  Figure   2-2(a)   shows  the typical  hydraulic
pathway  for  rapid infiltration.  A  much greater portion of the applied
wastewater  percolates  to  the  groundwater  than  with  slow  rate land
treatment.   There  is  little  or no consumptive use by plants and less
evaporation in proportion to a reduced surface area.
In  many  cases,  recovery of renovated water is an integral  part of  the
system.   This  can be accomplished using underdrains or wells,  as shown
in Figure 2-2(b, c).
Among  the case studies in Chapter 7 are three that serve as representa-
tive examples  of  rapid  infiltration  systems:   Phoenix, Arizona;  Lake
George, New York; and Fort Devens, Massachusetts.
     2.3.1   System Objectives


The  principal   objective of rapid infiltration is wastewater treatment.
Objectives  for the treated water can include:

     1.    Groundwater recharge

     2.    Recovery  of renovated water by wells or underdrains with  sub-
          sequent reuse or discharge

     3.    Recharge of surface streams by interception of groundwater

     4.    Temporary storage of renovated water in the aquifer
                                  2-9

-------
                 FIGURE  2-2

             RAPID INFILTRATION

                    APPLIED
                   •ASTEWATER
                                    EVAPORATION
                                   PERCOLATION
             (a) HYDRAULIC PATHWAY
                        FLOODING BASINS
                                -G R OU NOW A T E R
                                 PERCOLATION
                                 (UNSATURATED  ZONE)
(b) RECOVERY OF RENOVATED  WATER BY  UNDERDRAINS
                                  PERCOLATION
                               (UNSATURATED ZONE)
 (c)  RECOVERY  OF  RENOVATED WATER  BY  WELLS
                     2-10

-------
If  groundwater quality is being degraded by salinity intrusion,  ground-
water recharge  by  rapid infiltration can help to reverse the  hydraulic
gradient and protect the existing groundwater.


Return  of  the renovated water to the surface  by wells,  underdrains,  or
groundwater interception may be necessary or advantageous when  discharge
to  a  particular surface water body is dictated by senior water  rights,
or when existing groundwater quality is not compatible with expected re-
novated water  quality.  At Phoenix, for example, treated .water is with-
drawn immediately by wells to prevent spreading into the  groundwater and
to allow reuse of the water for irrigation [10],
     2.3.2  Treatment Performance
Removals  of  wastewater constituents by the filtering and straining  ac-
tion of  the soil  are excellent.  Suspended solids,  BOD,  and fecal  coli-
forms are almost completely removed in most cases [10, 11] .
Nitrogen  removals  are  generally poor unless specific operating  proce-
dures are established to maximize denitrification.   At Flushing  Meadows,
total  nitrogen  removals of 30% were obtained consistently.   In labora-
tory studies it was shown, however, that increased  denitrification could
have  been obtained by:  (1) adjusting application  cycles,  (2) supplying
an  additional   carbon source, (3) using vegetated  basins,  (4) recycling
the  portions  of the renovated water containing  high nitrate concentra-
tions, and  (5) reducing application rates [12].  Applying  some  of these
practices  in the field increased nitrogen removal,  resulting from deni-
trification, to  about  50%.   Although  total   nitrogen removals  may  be
poor,  rapid  infiltration  is  an  excellent  method  for   achieving  a
nitrified effluent.
Phosphorus  removals can range from 70 to 99%,  depending on the  physical
and  chemical   characteristics  of the soil.   As  with slow rate  systems,
the  primary removal mechanism is adsorption  with some chemical  precipi-
tation, so the long-term capacity is limited  by the mass of soil  in  con-
tact with  the  wastewater.   Removals are related also to the residence
time  of the wastewater in the soil and the travel distance (see Section
5.1.3).
2.4  Overland Flow
In  overland  flow  land treatment, wastewater is applied over the  upper
reaches of sloped terraces and allowed to flow across the vegetated sur-
face to  runoff collection ditches.  The wastewater is renovated by phy-
sical, chemical,  and  biological   means as it flows in a thin film down
the  relatively  impermeable  slope.  A schematic view of overland   flow
                                   2-11

-------
treatment  is  shown  in  Figure 2-3(a),  and  a   pictorial   view  of   a
typical  system  is  shown in Figure  2-3(b).  As  shown  in  Figure 2-3(a),
there  is  relatively  little  percolation involved  either because of  an
impermeable soil  or a subsurface barrier to percolation.
Overland flow is a relatively new treatment  process  for municipal waste-
water in  the  United  States.  As of  August 1976, only three  relatively
small,  full-scale  municipal  systems have  been  constructed.   These  are
located  in  Oklahoma, Mississippi, and South Carolina.   The earliest of
these  systems,  at Pauls Valley, Oklahoma,  is described  as a  case  study
in  Chapter  7.  In Melbourne, Australia,  overland flow has been used to
treat  settled  wastewater  for  several  decades  [13,  14].  The Campbell
Soup  Company treatment plant at Paris, Texas, which is perhaps the best
known of approximately 10 industrial  systems in the  county, is also des-
cribed as.a case study in Chapter 7.   Besides these  full-scale examples,
extensive  reference  is  made throughout this manual  to  the pilot  scale
municipal  studies sponsored by the EPA at Ada, Oklahoma, and  the bench-
scale greenhouse  studies  sponsored by the  Corps of Engineers at Vicks-
burg, Mississippi.
     2.4.1  System Objectives
The objectives of overland flow are wastewater  treatment  and,  to  a minor
extent,  crop  production.   Treatment  objectives   may be  either (1)  to
achieve  secondary  or  better  effluent  quality   from screened  primary
treated,  or lagoon treated wastewater,  or (2)  to  achieve high levels  of
nitrogen and BOD removals comparable to  conventional  advanced  wastewater
treatment from secondary treated wastewater.  Treated water is collected
at  the toe of the overland flow slopes  and can be  either reused  or  dis-
charged to surface water.  Overland flow can also  be used for  production
of forage grasses and the preservation of greenbelts and  open  space.
     2.4.2  Treatment Performance
Biological  oxidation,  sedimentation,  and grass  filtration  are  the  pri-
mary removal  mechanisms  for  organics  and   suspended  solids.   At  Ada,
using  raw comminuted wastewater,  Thomas  reported total  suspended solids
concentrations  of  6 to 8 mg/L in the  runoff  during  the summer  and  8  to
12  mg/L  in the winter [15].  BOD concentrations during the same period
were  7  to  11  mg/L  in the summer and  8 to  12  mg/L in the winter.   An
acclimation  or  seasoning  period of about 3  months  was required before
optimum removals were achieved.
Nitrogen  removal  is attributed primarily  to  denitrification.   Hunt has
reasoned that an aerobic-anaerobic double layer  exists  at the surface of
the soil and allows both nitrification and  denitrification to occur [16,
17].  Because  this process depends on two  stages  of microbial  activity,
it  is  sensitive to environmental conditions.   Plant uptake  of nitrogen
                                  2-12

-------
         APPLIED
        WASTEWATER
SLOPE  2-8»
                               FIGURE  2-3

                              OVERLAND FLOW
                         GRASS AND
                         VEGETATIVE LITTER
EVAPOTRANSPIRATION
                                                                RUNOFF
                                                                COLLECTION
                                 PERCOLATION
                        (a)  HYDRAULIC  PATHWAY
                                            SPRINKLER  CIRCLES
                                   RUNOFF
                                   COLLECTION
                                   DITCH
              (b)  PICTORIAL VIEW OF  SPRINKLER  APPLICATION
                                   2-13

-------
can also be a significant removal  mechanism.   Permanent  nitrogen  removal
by  plant  uptake  is only possible if  the  crop  is  harvested  and  removed
from  the field.  Ammonia volatilization  can  be  significant if  the  pH  of
the  water  is  above 7.   Nitrogen removals usually range  from  75 to 90%
with runoff nitrogen being mostly  in the  nitrate form.   Higher  levels  of
nitrate  and  ammonium  may occur  during  cold weather as a result of re-
duced biological activity and limited plant uptake.


Phosphorus is removed by  adsorption and precipitation in essentially the
same  manner  as  with  the  slow   rate  and  rapid  infiltration methods.
Treatment  efficiencies  are  somewhat  limited because of  the incomplete
contact between the wastewater and the  adsorption sites  within  the  soil.
Phosphorus  removals  usually  range from  30 to 60% on a concentration
basis.   Increased  removals  may   be  obtained  by  adding  alum  or ferric
chloride prior to application (see Section  5.1.4).
2.5  Other Processes
The  three  principal  land treatment processes,  when  implemented,  repre-
sent planned  and  engineered  changes  to  the  existing  environment.   Re-
cently, the  concept  of using natural  ecosystems,  such as wetlands,  for
wastewater  treatment has received considerable  attention.   Applications
of wastewater (1) to wetlands for treatment, and (2)  to the  soil  by  sub-
surface techniques are described in this  section.
     2.5.1  Wetlands
Wetlands, which constitute 3% of the land  area  of the  continental  United
States  [18], are intermediate areas in  a  hydrological  sense:   they  have
too  many  plants and too little water to  be  called lakes, yet they  have
enough  water  to  prevent most agricultural  or silvicultural  uses.   The
term  wetlands  is  used in this manual  to encompass areas also known as
marshes,  bogs, wet meadows, peatlands,  and swamps.  The ability of  wet-
lands to influence water quality is  the  reason  for much current research
on their use for wastewater management.
Three categories of wetlands are currently  used  for municipal  wastewater
treatment:

     •    Artificial  wetlands

     •    Existing wetlands

     •    Peatlands
                                  2-14

-------
Wetlands  are  discussed  in  more detail  in Section 5.1.5.  Peatlands are
discussed  separately   because these highly organic soils can be drained
and  managed  in   a  manner   similar  to  that  used  in  slow rate land
treatment.
     2.5.1.1  Artificial  Wetlands
Two  artificial  wetlands   treatment  systems have been developed at the
Brookhaven  National  Laboratory on Long Island, New York [19].  Both are
wetlands-pond  systems.   In the first,  the wetlands consist of wet mead-
ows merging  into   a  marsh  followed  by a pond (meadow-marsh).  In the
second  system,  the  wet   meadows  are deleted.  Both systems are being
loaded  at  an   application rate of about 25 in./wk (63 cm/wk).  Aerated
wastewater is applied and  recycling is  no longer employed.
These artificial wetlands  were formed in sandy soil by installing an  im-
pervious plastic liner  under the soil.   They were placed in operation in
June  1973.  Operating  modes have evolved from the original recycling to
the  present  once-through  approach with increasing loading rates until
April  1976,  when the  present rates were established.  Typical averaged
results  for July through  September 1975 for operation with a one-to-one
recycling of pond effluent are presented in Table 2-4.
                                 TABLE 2-4

                       TREATMENT PERFORMANCE FOR TWO
             ARTIFICIAL  WETLAND SYSTEMS ON LONG ISLAND [19]
                                   mg/L
                   Constituent
        Meadow-marsh  Wetlands
Influent   effluent    effluent
                  BOD              520        15        16

                  Suspended solids    860        43a       57a

                  Total nitrogen       36        3         4

                  Fecal coliforms,
                  count/100 mL      3,000        17b       21°


                  a.  Principally algae.

                  b.  Geometric mean.
                                   2-15

-------
The  wetlands area occupies 0.2 acre (0.08 ha)  and is flooded to a depth
of about 0.5 ft (0.15 m).  Small  recommends a 1  ft (0.3 m)  depth or more
to  prevent  volunteer  weed growth and to prevent washout during storms
[20].   Cattails  were  planted and duckweed (Lemna minor)  is prevalent.
Regular  harvest  of  cattails  is not practiced but weeds, grasses, and
cattails were thinned out in March 1976.
          2.5.1.2  Existing Wetlands
The  application  of  secondary effluent to existing freshwater and salt
water  wetlands  is being studied in Mississippi,  as well  as in Califor-
nia, Michigan,  Louisiana, Florida, and Wisconsin.  In Mississippi, Wol-
verton has  studied  the  use of water hyacinths in secondary wastewater
lagoons to effect removals of BOD, suspended solids, and nutrients [21].
A  surface  area  of  0.7  acre  (0.28 ha)  was used, and detention times
ranged  from 14 to 21 days.  The treatment performance of this system is
compared to that of a control lagoon free of water hyacinths for Septem-
ber 1975 as shown in Table 2-5.
                                TABLE 2-5

               TREATMENT CAPABILITY OF WATER HYACINTHS FED
                      OXIDATION POND EFFLUENT [21]
                                  mg/L
                                Hyacinth pond
                 Control pond
                  Constituent
Influent  Effluent Influent  Effluent
BOD
Suspended solids
Total Kjeldahl
nitrogen
Total phosphorus
TDS
22
43
4.4
5.0
187
7
6
1.1
3.8
183
27
42
4.5
4.8
390
30
46
4.5
4.6
380
Hyacinths  must  be harvested for effective nutrient removal.  Wolverton
suggests  harvesting  every 5 weeks during the warm growing season.  The
harvested  plants  may be processed into high-protein feed products, or-
ganic fertilizer and soil conditioner, or methane gas [22].


The  use  of  existing  wetlands  appears to hold promise as an emerging
technology  for wastewater management.  Management techniques for nutri-
ent removal,  loading  rates,  climatic  constraints  and  suitable site
characteristics need further study.
                                   2-16

-------
          2.5.1.3  Peatlands
The  use  of  peatlands  or  organic soils for land application has been
studied  by Farnham in Minnesota [23] and by Kadlec in Michigan [24].  A
system  has been designed by Stanlick [25] on the basis of Farnham1s re-
search.
Although  sprinkler  or  surface  application  techniques can be used on
peatlands,    the   North  Star  Campground  system  in  Minnesota  uses
sprinklers  [25].   It  was designed for 13.3 in./wk (33.8 cm/wk) and is
underdrained  at  a depth of about 3 ft (1 m).  Treatment efficiency for
1975 is summarized in Table 2-6.  Secondary effluent was applied.
                                TABLE 2-6

           TREATMENT PERFORMANCE OF PEATLAND IN MINNESOTA [25]
                                  mg/L
                        Constituent    Influent  Effluent
ROD
Suspended solids 	
Total nitrogen 20-40
Total phosphorus 10
Fecal col i forms, , j-
c
5
1-10
0.1

                      count/100 mL     10-10    0-4
Because  of  the  high  loading  rate,  the nitrogen uptake of the grass
planted  on the peat surface was surpassed.  Although the peat pH was 4,
the effluent pH was consistently between 6.5 and 7.5.
     2.5.2  Subsurface Application


Two  systems  that are quite similar to the peatland system are the soil
mound  and the subsurface filter systems.  The subsurface filter is des-
cribed in  the  Manual  of  Septic-Tank  Practice  [26].  The soil mound
system  used  by Bouma [27] and others is similar to the peatland system
in Minnesota, except that the application is by subsurface pipe.


The  soil mound system for a shallow soil over creviced rock is shown in
Figure 2-4.  Such systems are alternatives to treatment and discharge to
                                  2-17

-------
surface  waters where adverse  soil  conditions  exist.  The soil mound can
be used for [28]:

     1.   Shallow  soils   (<3   ft or  1 m)  over creviced or otherwise ra-
          pidly permeable  bedrock

     2.   Sites with slowly  permeable soils

     3.   Sites with seasonally high  groundwater
                                FIGURE  2-4

        SUBSURFACE APPLICATION TO  SOIL  MOUND  OVER CREVICED BEDROCK
                           EVAPOTRANSPIRATION
                            (GROWING SEASON)
                                                      VEGETATION
                                                            TOPSOIL
•••>;••'	• ••• ;	•	* '"I


 I   I   i   I   j  SOIL-FI
 APPLIED
 WASTEWATER
          ^^
 Mill
                                                             2 ft  (0.6m)
                            ORIGINAL SOIL
                                                     CREVICED BEDROCK
Bouma has reported on  an  experimental  soil  mound system at Sturgeon Bay,
Wisconsin  [27],  The  work   is  part  of  the Small Scale Waste Management
Project  at  the  University  of  Wisconsin.    The  mound, shown in Figure
2-4,  was  designed for 2 in./d  (5  cm/d)  but was actually dosed at about
half  of  that  rate.   Septic   tank  effluent was dosed four times a  day
through  a  network of 1  in.  (2.5 cm)  PVC pipes.  The actual loading  was
6.4  in./wk (16.3 crn/wk). Treatment  performance of this mound system is
given in Table 2-7.
                                   2-18

-------
                                 TABLE 2-7
                 TREATMENT PERFORMANCE OF AN EXPERIMENTAL
                    SOIL MOUND SYSTEM IN WISCONSIN [27]
                                   mg/L
                          Constituent
Influent  Effluent
BOD
COD
Ammonia nitrogen
Total nitrogen
Total phosphorus
Fecal col i forms,
count/mL
Total col i forms,
count/raL
90
256
56
62
15

2,500

37,000
0
42
2
56
8

5

54
2.6  References
1.  Evaluation of Land Application Systems.   Office  of  Water  Program
    Operations,  Environmental  Protection  Agency.    EPA-430/9-75-001.
    March 1975.

2.  Sullivan, R.H., et al.   Survey of Facilities Using Land  Application
    of  Wastewater.   Environmental  Protection  Agency, Office of Water
    Program Operations.  EPA-430/9-73-006.  July 1973.

3.  Kardos, L.T., W.E.  Sopper, E.A.  Myers,  R.R.   Parizek,  and  J.B.
    Nesbitt.   Renovation  of  Secondary  Effluent  for Reuse as a Water
    Resource.  Environmental  Protection Agency, Office of  Research  and
    Development.   EPA-660/2-74-016.  February 1974.

4.  Michigan State University, Institute of Water Research.   Utilization
    of Natural  Ecosystems for Wastewater Renovation.  Final   Report  for
    Region  V  Office,  Environmental   Protection Agency.  East Lansing,
    Mich.   March  1976.

5.  Cole.D.W. University of Washington.  Personal Communication. May 1977.

6.  Jackson, W.G. , R.K. Bastian and J.R. Marks.  Effluent Disposal in an
    Oak Woods During Two Decades.   Publications in Climatology.   25(3):
    20-36.   1972.

7.  Uemirjian,  Y.A.  Land Treatment of Municipal  Wastewater  Effluents,
    Muskegon County Wastewater System.   Environmental  Protection Agency,
    Technology Transfer.  1975.
                                    2-19

-------
 8.  Iskandar, I.K.,   R.S.  Sletten,   D.C.  Leggett,   and   T.F.  Jenkins.
     Wastewater  Renovation  by  a  Prototype   Slow  Infiltration   Land
     Treatment  System.  Corps  of  Engineers,   U.S.   Army  Cold   Regions
     Research and Engineering Laboratory.    CRREL  Report 76-19.   Hanover,
     N.H.  June 1976.

 9.  biroadbent, F.E.   Nitrification  and   Denitrification  of Municipal
     Wastewater  Effluents Disposed to Land.   Prepared for the California
     Water Resources Control Board.   University  of   California,  Davis.
     February 1976.

10.  Bouwer,  H.,  R.C.   Rice,  and  E.D.   Escarcega.    High-Rate  Land
     Treatment I:  Infiltration and Hydraulic   Aspects  of  the  Flushing
     Meadow   Project.   Jour.   WPCF. 46:834-843,   May 1974.

11.  McMichael,  F.C.   and  J.E.   McKee.   Wastewater  Reclamation   at
     Whittier  Narrows.   California  State Water Quality Control Board.
     Publication No.  33.  1966.


12.  Bouwer, H., J.C.  Lance, and M.S.  Riggs.   High-Rate Land Treatment
     II:   Water  Quality  and  Economic Aspects  of  the Flushing Meadows
     Project.  Jour.   WPCF.  46:844-859,    May 1974.

13.  Seabrook,  B.L.   Land  Application of  Wastewater  in   Australia.
     Environmental    Protection   Agency,    Office   of  Water Programs.
     EPA-430/9-75-017.  May 1975.

14.  Melbourne and  Metropolitan  Board of Works.   Waste  into  Wealth
     (Wastewater Treatment by Irrigation).   Melbourne, Australia.  1971.

15.  Thomas, R.E.,  K.  Jackson,  and L.   Penrod.  Feasibility of   Overland
     Flow  for  Treatment  of  Raw  Domestic  Wastewater.    Environmental
     Protection Agency, Office of Research  and   Development.    EPH-66Q/2-
     74-087.'  July  1974.

16.  Hunt P.G.   and C.R.   Lee.   Overland Flow Treatment  of Wastewater - A
     Feasible   Approach.     In:     Land   Application   of   Wastewater.
     Proceedings  of a Research Symposium Sponsored by  the  USEPA,  Region
     III,  Newark,  Del.  November 1974.

17.  Carlson, C.A., P.G.   Hunt,  and T.B.    Delaney, Jr.    Overland Flow
     Treatment of Wastewater.   Army Engineer Waterways Experiment Station.
     Miscellaneous  Paper Y-74-3.   August 1974.

18.  Witter, J.A. and S.  Croson.   Insects and Wetlands.   In:   Proceedings
     of the National  Symposium on Freshwater Wetlands  and Sewage  Effluent
     Disposal.    University  of   Michigan.   Ann   Arbor,    May 1976.  pp
     269-295.

19.  Small,  M.M.   Meadow/Marsh  Systems   as   Sewage  Treatment   Plants.
     brookhaven National  Laboratory.   BNL20757.    Upton,   N.Y.    November
     1975.
                                   2-20

-------
20.  Small, M.M.  Marsh/Pond Sewage Treatment Plants.   In:   Proceedings
     of the National Symposium on Freshwater Wetlands and Sewage Effluent
     Disposal.   University  of  Michigan.   Ann  Arbor,  May  1976.    pp
     197-214.

21.  wolverton, B.C.  and R.C.  McDonald.  Water Hyacinths for  Upgrading
     Sewage Lagoons to Meet Advanced Wastewater Treatment Standards,  Part
     1.   NASA  Technical  Memorandum TM-X-72729.   Bay St.  Louis,   Miss.
     October 1975.

22.  Wolverton, B.C.  et al.   Bio-conversion  of   Water  Hyacinths  into
     Methane  Gas:   Part  1.  NASA Technical Memorandum TM-X-72725.   Bay
     St.  Louis, Miss.  July 1975.

23.  Farnham, R.S.   and  D.H.   Boelter.   Minnesota's  Peat  Resources:
     Their  Characteristics and Use in Sewage Treatment, Agriculture,  and
     Energy.  In:  Proceedings of the National  Symposium  on   Freshwater
     Wetlands and Sewage Effluent Disposal.   University of Michigan.   Ann
     Arbor, May 1976.  pp 241-256.

24.  Kadlec, J.A.  Dissolved Nutrients in a  Peatland near Houghton   Lake,
     Michigan.  In:  Proceedings of the National Symposium  on Freshwater
     Wetlands and Sewage Effluent Disposal.   University of Michigan.   Ann
     Arbor,  May 1976.  pp 25-50.

25.  Stanlick, H.T.  Treatment of Secondary  Effluent Using  a  Peat  Bed.
     In:  Proceedings of the National Symposium  on  Freshwater  Wetlands
     and  Sewage  Effluent Disposal.  University of Michigan.  Ann  Arbor,
     May 1976.  pp 257-268.

26.  Manual  of  Septic-Tank  Practice.   U.S.    Department  of   Health,
     Education, and Welfare.  Public Health  Service Publication No.  526.
     Revised 1967.

27.  Bouma, J., et al.  An Experimental  Mound  System  for  Disposal   of
     Septic  Tank  Effluent  in Shallow Soils Over Creviced Bedrock.   In:
     Proceedings of  the  International  Conference  on  Land  for   Waste
     Management, Ottawa, Canada,  October 1973.  pp 367-377.

28.  Bouma, J.  Use of Soil for Disposal and  Treatment  of  Septic  Tank
     Effluent.   In:   Water  Pollution  Control   in  Low  Density  Areas,
     Proceedings  of  a  Rural  Environmental   Engineering   Conference,
     Jewell, W.J.  and R.  Swan, (ed.).  Hanover,  The University Press of
     New England,  1975.  pp 89-94.
                                    2-21

-------
                                CHAPTER 3

              TECHNICAL PLANNING AND FEASIBILITY ASSESSMENT


3.1  Purpose and Scope


The  purpose  of  this  chapter  is  to  describe  those aspects of  land
treatment  that  are  important  to a technical  and economic feasibility
assessment.  The major divisions of this chapter are:

     •    Approach to development of alternatives

     •    Evaluation of unit processes

     •    Wastewater quality

     •    Regional site characteristics

     •    Other planning considerations

     t    Evaluation of alternatives
The scope of the chapter is directed at those factors that are unique  to
the formulation and evaluation of land treatment alternatives.  Planning
and   feasibility   considerations   that  are  common  to  conventional
wastewater management systems are adequately discussed elsewhere.


It is important to be aware of the distinction made between "alternative
land   treatment   processes"  (described  in  Chapter  2)  and  "system
alternatives."   The  term  "land  treatment process" .refers to the unit
process  only  (e.g., slow rate, overland flow) whereas the term "system
alternatives"   includes   the  entire  wastewater  management  facility
(transmission,  treatment  processes,  storage, collection, and discharge
facilities).

This chapter presents planning level information related to unit process
selection,  the  wastewater  characteristics important to land treatment
systems,  and  the  significant  regional  characteristics  involved  in
developing  land treatment system alternatives.  It is expected that the
user  will  also  refer  to  Chapter  5, or for small systems Chapter  6,
during  the  feasibility assessment to obtain more technical details for
the development of alternative systems.  The evaluation of the resulting
systems is then discussed in Section 3.7.
                                   3-1

-------
3.2  Approach to Development of Alternatives


Three  major  factors  combine  to  determine  the type of land treatment
process that can be used on a given site:

     1.  Soil permeability

     2.  Wastewater quality

     3.  Discharge quality criteria

For  a  given  site, the soil permeability  can be determined.   The  other
two  factors,  however, must be considered  as  variables.   The  wastewater
quality  to  be  applied  depends  on  the preapplication  treatment.  The
discharge  criteria  are also variable because there  is a choice  between
surface  water and groundwater discharge.   There  is also  the possibility
of  collecting  the  treated  water  for other  uses  in agriculture  or
industry.
The  many variables and options associated  with  land treatment processes
and  systems  require  the  use  of an organized,  systematic  approach  to
selecting  alternatives.    Many approaches  have  been considered but  only
three  have  been  commonly  used.    The  three most common  approaches  to
developing land treatment alternatives are:

     1.   No constraints  approach—There  are  no  prior constraints  placed
          on  the  study.   The  entire  study   area is  investigated for
          potential  sites  while considering the  whole  spectrum of  land
          treatment processes and combinations to  develop alternatives.

     2.   Process constrained approach—The study  begins with some prior
          constraints   that  limit  consideration  of  alternatives  to
          certain   land   treatment   processes.    Potential   sites  are
          identified  within  the  reduced  spectrum  of land treatment
          processes created by the constraints.

     3.   Site-constrained  approach—A predetermined site  (or sites)  is
          available,  and treatment processes are  evaluated to match the
          site(s) and the project objectives.


The  approach  to  the  development  of  land treatment alternatives  is
iterative  in  nature,  as  illustrated  in  Figure 3-1.  This iterative
process  is  best  achieved  in the no-constraints approach.   Within the
iterative   cycle  of  site  identification,  site  evaluation,  process
assessment,  and  planning  implications  assessment,  there  are so  many
degrees  of  freedom  available that several  cycles or iterations  may  be
necessary  to  define  and  develop  an alternative.   When  the number  of
sites  or  processes  is  predetermined, as  in the  process-constrained  or
site-constrained approach, fewer alternative  systems can be developed.
A  variation  of  the no-constraints  approach  is  the  use  of  an  inductive
analytical    planning   process.    Regional  goals  and   objectives   are
                                  3-2

-------
                                                                 FIGURE  3-1
                                 PLANNING SEQUENCE FOR THE DEVELOPMENT OF  LAND TREATMENT  ALTERNATIVES
                             IDENTIFY STUDY
                             AREA GOALS
                             AND
                             OBJECTIVES
                                                    IDENTIFY
                                                    POTENTIAL
                                                    LAND TREATMENT
                                                    AREAS OR SITES
                                    DETERMINE
                                    WASTEWATER
                                    TREATMENT
                                    NEEDS
oo
i
OJ
EVALUATE
SITE
CHARACTERISTICS
                                            DEVELOP
                                            LAND  TREATMENT
                                            ALTERNATIVES
                                          \
                                                                     ASSESS
                                                                     PLANNING
                                                                     IMPLICATIONS
EVALUATE
LAND TREATMENT
ALTERNATIVES
                                                  ASSESS
                                                  LARD TREATMENT
                                                  PROCESSES

-------
initially  identified  and the ability of land treatment to help achieve
these  and  other  benefits is assessed.  Included are the possibilities
for  reclamation  and  resource  recovery such as recycling of nutrients
through  the  production  of cash crops, preservation of agriculture and
open   space,   and  the  implementation  of  other  land  use  planning
objectives.   Thus,  land  treatment  may be viewed as a means to an end
rather than an end in itself.
3.3  Evaluation of Unit Processes


To evaluate the applicability of land treatment processes, the treatment
objectives and wastewater quality must be known.  The preliminary design
of  land  treatment  processes  can  then  be accomplished using average
flowrates  and  hydraulic  loading  rates.   In  this section, hydraulic
loading  rates  are discussed for each land treatment process.  Guidance
is  then  provided  for  preliminary  planning  purposes  on  land  area
requirements,   preapplication   treatment,  storage,  and  recovery  of
renovated water.
     3.3.1  Land Treatment Processes
The  first  step  in  evaluating  land  treatment  unit  processes is to
identify  the  processes  that  may be suitable for the requirements and
conditions  of  the  study  area.   The description of treatment process
capabilities   and  objectives  in  Chapter  2  will  provide  a  useful
background for this purpose.  The types of factors that should generally
be considered at this stage include:

     •    The ability of each process to meet treatment requirements

     •    The  disposition  of  applied  wastewater in relation to water
          needs

     •    The  predominant  characteristics  of  the study area that may
          dictate certain land treatment processes

     •    The desired secondary objectives, such as increased irrigation
          water supply


          3.3.1.1  Slow Rate Process
For  the slow rate process, the hydraulic loading  rate can  be  determined
initially from the use of  the water balance:


     Precipitation + Wastewater applied = Evapotranspiration + Percolation + Runoff     (3-1)
                                    3-4

-------
Effluent runoff is usually not desirable for the slow rate process.   For
planning,  the relationship between precipitation and evapotranspiration
on  a  mean  annual  basis  can  be  taken  from  Figure  3-2.   If   the
precipitation  and evapotranspiration balance, an estimate of wastewater
application  rates  can  be  made  from  the  soil  permeability rates as
presented in Figure 3-3.  For example, a slow permeability soil could be
loaded  at  1.0  to  3   in./wk (2.5 to 7.6  cm/wk) from Figure 3-3.   If
evapotranspiration  exceeds  precipitation,  the effluent applied can be
increased   to   equal  the  sum  of  net  evapotranspiration  and  soil
permeability.  For example, in central Texas, where  net evapotranspira-
tion is 36 in./yr (90 cm/yr), the application rate could be increased by
0.7  in./wk  (1.8  cm/wk)  on an annual average to a total of 1.7 to 3.7
in./wk (4.3 to 9.4 cm/wk).  Application rates beyond 4 in./wk (10 cm/wk)
are  normally  defined  as  rapid  infiltration  and  involve  different
considerations.
The shaded area in Figure 3-3 represents the range of average, long-term
infiltration  rates when considering only soil  permeability derived from
clear  water.   The  range  of  values  shown in Figure 3-3 as "Range of
Application  Rates  in  Practice" is indicative of the many factors that
must  be  considered  in  selecting  the  final  application rate.   Such
considerations   include  crop  water  needs  and  tolerances,  nutrient
balance,  and  reductions in application rates for crop harvesting  or to
account for algae in the wastewater.


The  hydraulic  loading  is  also  affected  by  the  climate  and   crop
selection.   The climate will affect the growing season and will  dictate
the  period  of  application  and  the amount of storage required.   Crop
water tolerances and nutrient requirements can directly affect hydraulic
loading rates.  The following factors affect the selection of crops:

     1=   Suitability to local climate and soil conditions

     2.   Consumptive water use and water tolerance

     3.   Nutrient uptake and sensitivity to wastewater constituents

     4.   Economic value and marketability

     5.   Length of growing season

     6.   Ease of management

     7.   Public health regulations


          3.3.1.2  Rapid Infiltration Process


Rapid  infiltration  systems  are  designed  on  the  basis of hydraulic
capacity of the soil and the underlying geology.  The relationship  shown
in  Figure 3-3 can be used for approximation of hydraulic loading rates,
                                   3-5

-------
                                                                FIGURE 3-2

                                  POTENTIAL  EVAPOTRANSPIRATION  VERSUS  MEAN ANNUAL PRECIPITATION  [1]
                                                                  Inches
CT)
                                    + 30
                                     + 50
                                 1  \ n. = 2. 54 cm
                                                                                                       -5
                                                                    + 50
                                                                       + 30
                              f POTENTIAL EVAPOTRANSPIRATION MORE THAN
                                MEAN ANNUAL  PRECIPITATION

                              - POTENTIAL EVAPOTRANSPIRATION LESS THAN
                                MEAN ANNUAL  PRECIPITATION

-------
1000
 0.1
                                 FIGURE 3-3

           SOIL PERMEABILITY VERSUS  RANGES  OF  APPLICATION RATES
              FOR  SLOW RATE  AND RAPID INFILTRATION TREATMENT
                                      PROBABLE
                                      LONG TERM
                                      FOR
          INFILTRATION
                  OF APPLICA
                  IN PRACTrC
                                                           ARBITRA
                                                           BETWEEN
                                                           AND RAP
                                                           SYSTEMS
SLOV RATE
SYSTEMS
Y DlVISIOi
SLOV  RATE
D INFILTR
          PERMEABILITY RATES OF MOST RESTRICTIVE LAYER  IN SOIL PROFILE,  in./h
PERMEABILITY* SOIL CONSERVATION SERVICE DESCRIPTIVE TERMS
VERY SLOV
< 0.06
SLOV
0.06-0. 20
MODERATE-
LY SLOV
0.20-0.60
MODERATE
0. 60-2. 0
MODERATE-
LY RAPID
2.0-6.0
RAPID
6.0-20. 0
VERY RAPID
> 20.0
     *  MEASURED VITH CLEAR VATER

     1  in./«ik- 2.54 cn/wk
                                      3-7

-------
if the permeability of the most restrictive  layer in  the  soil  profile  is
known.  Application  rates  in the low end of  the range should be  chosen
if  any  of  a  number  of conditions exist  which may be  adverse.   These
include:    (1) wide   variations  in  soil  types and    permeability,
(2) shallow soil  profiles,  and  (3) shallow   or  perched water tables.
Reductions  in  application rates may also be  necessary if the system  is
to  be  managed  to  optimize  denitification.    The  cycle of  wastewater
application and resting must be defined.
          3.3.1.3  Overland Flow Process
For  overland  flow,  the  application  rate   depends   primarily   on  the
expected   treatment   performance   and  the   level   of  preapplication
treatment.  If  primary  effluent  is  used,   an  application  rate  in  the
range  of  2.5  to  6  in./wk  (6.4 to 15  cm/wk)  is  usually necessary to
produce  the effluent quality shown in Table 2-2.  The lower  end of  this
range  should  be  considered where:   (1)  terrace slopes will  be greater
than  about  6%,  (2) terraces  are  less   than  150   ft  (45   m)  long,
or  (3) climatic conditions are poor.  The upper  end  of the scale  can be
used  when  evapotranspiration rates  are high,  or when a moderate  amount
of  percolation  can be expected to take place.   In  cases where overland
flow  is  to  be  used  as a polishing process  or for  advanced treatment
following preapplication treatment, application rates  as high  as 6 to 16
in./wk  (15  to  40  cm/wk)  may be used.   These  rates have been used in
demonstration  systems  with  slopes   of  2 to  3% that are 120 ft  (36 m)
long.
          3.3.1.4  Combinations
Combinations  of  land  treatment processes in series can be considered.
Examples  of two such systems are shown schematically in Figure 3-4.   In
the  first  example,  rapid  infiltration is used after overland flow to
further  reduce concentrations of BOD,  suspended solids, and phosphorus.
Because  of  the increased reliability  and overall  treatment capability,
the application rates for the overland  flow process could be higher than
normal.
In the second example, the rapid infiltration process precedes slow rate
treatment.   The  recovered  renovated  water  should meet even the most
restrictive  requirements  for  use on food crops.   The unsaturated zone
can be used for storage of renovated water to be withdrawn on a schedule
consistent with crop needs.
                                   3-8

-------
                                                              FIGURE  3-4

                                                    EXAMPLES OF COMBINED SYSTEMS
                          PREAPPLICATION
                            TREATMENT
STORAGE
OVERLAND
  FLOW
   RAPID
INFILTRATION
OPTIONAL
RECOVERY
  WELLS
DISCHARGE
CO
vo
                                         a) OVERLAND FLOW FOLLOWED  BY RAPID  INFILTRATION
\ ' / S
1
MM, y^ s-~*J>-^J>-^J>-
^M^
PREAPPLICATION RAPID RECOVERY SLOW RATE
TREATMENT INFILTRATION WELLS TREATMENT
                                      b) RAPID  INFILTRATION FOLLOWED BY SLOW  RATE  TREATMENT

-------
     3.3.2  Land Area Requirements
The total land area required for a land treatment system consists  of the
actual  land  to  which  wastewater  is  applied  and the additional  area
required  for  buffer  zones,  storage reservoirs,  access roads, pumping
stations,  preapplication  treatment,  and maintenance and administration
buildings.   In addition, it may be necessary  to  set aside some land for
future expansion or emergencies.


The  total  land  area  requirement  can  be   estimated  for preliminary
planning using the nomograph in Figure 3-5.  To use the nomograph,  first
draw   a   line  through  appropriate   points  on  the  design-flow  and
application-rate  axes  to  the pivot  line.  Draw a second line from the
intersection  of  the  first  line  with  the  pivot  line  through  the
appropriate  point on the nonoperating time axis.  (Nonoperating time is
the  period  during the year when the  system is shut down for weather or
other  reasons.)   The  calculated  total  area   is  then  noted   at the
intersection  of  that  axis  with  the  second   line.   This total  area
includes land for application, roads,  storage, and buildings.  The  total
area  with  a  200 ft (61 m) wide buffer zone  allowance is read from the
right-hand side of the axis; the total  area with  no allowance for  buffer
zones is read from the left-hand side.
     3.3.3  Preapplication Treatment
Preapplication treatment of wastewater may  be  necessary  for a  variety  of
reasons,  including (1)   maintaining a  reliable   distribution   system,
(2) allowing storage of wastewater without  creating nuisance conditions,
(3)  obtaining  a  higher  level   of  wastewater   constituent    removal,
(4) reducing  soil   clogging, and (5) reducing possible  health risks.   A
summary of preapplication treatment practice  is presented in Table  2-1.
     3.3.4  Storage


Storage  is  provided  primarily for nonoperating  periods  and  periods  of
reduced  application rates resulting from climatic constraints.   In  most
situations,  however, where this requirement  is  small,  storage may  still
be   necessary   for   system  backup,   flow   equalization,  and proper
agricultural  management  including  periods   for   harvesting.   In  the
planning   stage,   it  will   usually  be  important  to  determine  the
approximate  volume required for each land treatment alternative so  that
storage costs can be estimated.


It  has  been  shown that slow rate and overland flow irrigation systems
can  usually  operate  successfully below 32°F (0°C), and  25°F (-4°C)  is
                                  3-10

-------
20 -=>
15 —
10

 9

 8


 7


 6
 3 -^
 9 ——
     s
                                                FIGURE  3-5

         TOTAL  LAND REQUIREMENT  (INCLUDES  LAND FOR  APPLICATION, ROADS, STORAGE, AND  BUILDINGS)
                                100 —



                                 50  -
                              -   10 —
                              a

                                   5  H

                                 0.5  -
                                 0.1 —


1  in./ 1 wk = 2.54 cm/ wk

1  Mgal/ d = 43.8 L/S
1  ACRE = 0.405 ha
                                         30000 —|


                                         20000 —




                                         10000




                                          5000
                                                            —   30000


                                                            —   20000
                                                            —  10000
                                                                5000
                                        .  1000
                                       oe



                                       =   500
                                                       50  -
                                                       10 —
                                                        5 —'
                                                                     ut
                                                                     Ul
                                                                     ec.
                                                                     u
.  1000 u.,


      0


 500   J[
                                                                                SAMPLE  PLOT
    25



*   20
Ul


^   15-^

CO

5 -10 •


cc
Ul

o    5 —
z
o      -



     o —
                                                            —  100
                                                            -  50
                                                            — 10
                                                                                            SAMPLE PLOT




                                                                                      DES I GN FLOt   3 M ga I /d

                                                                                      APPL. RATE     1.5 IN. /WK


                                                                                      NONOPER.  TIME  10 WK

                                                                                      READ: goo ACRES «ITH  BUFFER

                                                                                           750 ACRES WITHOUT BUFFER

-------
sometimes  used  as a lower limit.   A conservative  method  for  predicting
the  number  of  days  that are too cold for  operation  is  to assume  that
application  is  suspended  on all  days  in  which  the  mean  temperature  is
below  32°F  (0°C).   This  method   has   the   advantage of using  readily
accessible data.
The National Climatic Center in Asheville,  North  Carolina,  has  conducted
an  extensive  study  of  climate  and weather  variations  throughout  the
United  States.   A  computer  program has  been developed  to  use weather
station  data in estimating the amount of wastewater storage  required at
a  location  because  of  climatic   constraints  [2].    For planning  and
preliminary  feasibility  assessment,   a  value  for storage  days  can be
found using Figure 3-6.  The map gives the  number of nonapplication days
for which storage would normally be required  for  a 20 year return  period
on  the basis of climatic factors alone.  Additional  storage  time  may be
required if reduced winter loading  rates are  used for overland  flow (see
5.1.4.1).
Rapid  infiltration basins which are intermittently flooded  can  often  be
operated year-round regardless of climatic  conditions.   The  only storage
that  might  be  required  is that for system  backup or extremely severe
climatic  conditions.   During  extended periods  of cold weather, an  ice
layer  may form on the surface of the bed.   However, at Lake George,  New
York,  and  at  Fort  Devens, Massachusetts, this has not proved to be a
problem.   The  application  of the wastewater merely floats the ice  and
infiltration continues.  This condition should prevail  whenever  the soil
is porous and well drained; otherwise, precautions are advised.
     3.3.5  Recovery of Renovated Water
Recovery of the applied wastewater after renovation for reuse or further
treatment  is  often  a part of the overall  land treatment process.   The
means  to recover renovated water include (1)  surface runoff collection,
(2) underdrains,  (3) recovery  wells,  and   (4) tailwater  return.   The
applicability  of these systems to the treatment processes is summarized
in  Table  3-1.    These  recovery  methods   are  described  in  various
situations in Chapter 5.
3.4  Wastewater Quality
Knowledge  of  the  quality of the wastewater to be treated is needed in
planning  to  properly  assess preapplication treatment needs or special
management  needs.  The major constituents in typical  untreated domestic
wastewater  are  presented in Table 3-2.  Preapplication treatment using
primary  sedimentation  will  reduce  BOD   and  suspended  solids (SS),
but  will  not  greatly  affect  nitrogen  or phosphorus concentrations.
Treatment  in  oxidation  ponds,  aerated  lagoons,  or other biological
                                 3-12

-------
                                                                    FIGURE  3-6
                                                    ESTIMATED WASTEWATER  STORAGE  DAYS BASED
                                                        ONLY  ON CLIMATIC  FACTORS  [2]
                                 J 20
GO
I
u>
                           SHADING  DENOTES REGIONS WHERE
                           THE  PRINCIPAL CLIMATIC CONSTRAINT
                           TO APPLICATION OF WASTEWATER
                           IS PROLONGED WET SPELLS
                                                                                                          I 60
                                                                                                       BASED ON  32°'F (0°C)
                                                                                                       MEAN  TEMPERATURE
                                                                                                       0.5 in./d PRECIPITATION,
                                                                                                       1  in.  OF  SNOWCQVER
1  in.= 2.54 en

-------
treatment  processes   further   reduces   the
nitrogen or phosphorus.
                         BOD   and SS,  and  may reduce
                                    TABLE 3-1

                       APPLICABILITY  OF RECOVERY SYSTEMS
                               FOR RENOVATED  WATER
        Recovery system
                            Slow rate
                    Rapid infiltration     Overland flow
    Surface runoff collection
      Effluent
      Stormwater

    Underd rains


    Recovery wells

    Tail water
      Sprinkler application
      Surface application
NA                  NA
Sediment control       NA

Groundwater control    Groundwater control
and effluent recovery  and effluent recovery
Usual ly NA
NA
25-50% of applied
flow
Groundwater control
and effluent recovery

NA
NA
Collect3

Erosion control

NA


NA


NA
NA
    NA = not applicable.
    a.  Disinfect if required before discharge;  provide for short-term recycling of waste-
       water after extended periods of shutdown, if effluent requirements are stringent.
                                     TABLE  3-2

                       IMPORTANT  CONSTITUENTS  IN TYPICAL
                             DOMESTIC WASTEWATER [3]
                                       mg/L
                                              Type of wastewater
Constituent
BOD
Suspended solids
Nitrogen (total as N)
Organic
Ammonia
Nitrate
Phosphorus (total as P)
Organic
Inorganic
Strong
300
350
85
35
50
0
20
5
15
Medium
200
200
40
15
25
0
10
3
7
weak
100
100
20
8
12
0
6
2
4
Land   treatment   processes   are capable of  removing  large  amounts  of BOD
and   SS  as  well   as   nutrients,   trace  elements,   and microorganisms.
                                      3-14

-------
 Hydraulic  loading rates were discussed  in  the  previous section and will
 usually  govern  site  area.  However, in some  cases constituent loading
 rates  may  dictate land area needs.  For preliminary planning purposes,
 the  BOD  loading  rate guidelines  in Table 3-3 can  be used to determine
 whether  hydraulic  or  constituent loadings   will   control  the design.
 Using  hydraulic  application  rates appropriate for the process and the
 BOD  concentrations  of the wastewater,  BOD loadings can be computed and
 compared with the values in Table 3-3.


                                 TABLE 3-3

                         TYPICAL BOD LOADING RATES
                                 lb/acre-d
                            Slow rate  Rapid infiltration  Overland flow
                Typical range
                for municipal
                wastewater^    0.2-5       20-160           5-50
                a.  Loading rates represent total annual  loading divided by
                   the number of days in the operating season.
Exceeding   the  typical   values  in  Table  3-3  will not necessarily be
detrimental  to the system.  The planner or engineer should be aware  that
special  management  may  be  required  above  these  values and provide
appropriate  safeguards.  Loading rates are discussed in detail for  each
process  in  Section 5.1.


For   trace   elements, the concentrations in wastewater vary tremendously
with   location  and percentage of industrial  flows.  Ranges of values in
untreated   wastewater,   primary  effluent,  and  secondary  effluent are
presented in Table 3-4.   Also included in Table 3-4 are the EPA drinking
water standards  for these constituents for comparison.  Concentrations
of trace elements  in the wastewater after preapplication treatment which
are   equal   to  or less  than those recommended for drinking water should
represent   no management  concern.   If one or more values is expected to
exceed  these  recommendations,   the  more  detailed discussion of trace
element loadings should  be consulted in Section 5.1.


3.5   Regional  Site  Characteristics


Compared  to  other  forms  of wastewater treatment,  land treatment systems
and  processes   are  very  site  specific.   The  objective of characterizing
physical   features   of   the  region   is  to provide the basic  information
necessary  to  make  a preliminary assessment  of land treatment processes
and  systems within  the  study  area.   The physical  regional  features that
are  considered  important include:   topography, soils,  geology,  climate,
                                   3-15

-------
surface  water  hydrology   and   quality,   and   groundwater hydrology and
quality.  In this  section,  these topics,  along  with sources of data, are
discussed  as  they   relate to  the  land  treatment processes described in
Chapter 2.
                                TABLE  3-4

               CONCENTRATION  OF TRACE  ELEMENTS  IN  VARIOUS
                            U.S. WASTEWATERS
                                  mg/L
Element
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Manganese
Mercury.
Nickel
Zinc
Untreated
wastewatera
0.003
0.004-0.14
0.02-0.700
0.02-3.36
0.9-3.54
0.05-1.27
0.11-0.14
0.002-0.044
0.002-0.105
0.030-8.31
Primary
effluents3
0.002
0.004-0.028
<0. 001 -0.30
0.024-0.13
0.41-0.83
0.016-0.11
0.032-0.16
0.009-0.035
0.063-0.20
0.015-0.75
Secondary
effluents3
<0. 005-0. 01
0.0002-<0.02
<0. 010-0. 17
0.05-0.22
0.04-3.89
0.0005-<0.20
0.021-0.38
0.0005-0.0015
<0. 10-0. 149
0.047-0.35
EPA recoircnended
drinking
water standards'3
0.05
0.01
0.05
1.0
0.3
0.05
0.05
0.002
No standard
5.0
         a.  The concentrations presented encompass the range of values reported in
             references [4, 5, 6, 7, 8, 9, 10, 11].

         b.  Reference [12].
     3.5.1  Site  Identification
The  complexity  of  site  identification  depends  on the size of the study
area and the nature  of  the  land use.   One  approach is to start with land
use plans and identify  undeveloped  land.   A  tool  that can be used is the
map overlay technique.  Map  overlays can help  the planner or engineer to
organize  and study  the combined effects of  land use, slope, relief, and
soil permeability.   Criteria can be set  on these four factors, and areas
that  satisfy  the   criteria  can then be  located.  If this procedure is
used  as  a preliminary step in site identification, the criteria should
be  reassessed,  during  each  successive   iteration.   Otherwise, strict
adherence  to  such   criteria may  result  in overlooking either sites or
land treatment opportunities.
                                   3-16

-------
Information required to make a map overlay  includes:


                    	Source	  	Information	

                    USGS quad sheets  Base map with topography

                    Land use maps    Existing and future  land use

                    Soil maps       Soil permeability and slope





     3.5.2  Site Selection
The  process  of  characterizing,  evaluating,   and   selecting   sites  is
usually  iterative  in  nature.  The  first  screening  of  sites  may be  done
using  overlays  or  considering  only   land  use  and soil  permeability.
Subsequent  evaluations  include  factors   such  as   those  presented  in
Table 3-5.
Once the full array of  site characteristics  is  assembled,  and sites  have
been  screened  for  acceptability,   the   selection   process  can  include
numerical  rating  systems.   The  relative effect  of  each  characteristic
can  be determined by assigning weighting  values.  The resulting  ratings
should  include  input  from  as many  qualified  planners and engineers  as
possible to reduce bias.


     3.5.3  Topography
Three  main  topographic  features  that  affect  the  suitability  of a site
for land treatment of wastewater  are:  slope, relief,  and susceptibility
to  flooding.   These  features   play  a  major  role  in the preliminary
identification  and  evaluation   of potential   sites.   A less  important
topographic  feature--aspect--may   also   affect  site   suitability.  The
amount  of  solar radiation  a  site  receives  is  related to the aspect,  or
direction,  of the slope.  This will affect  the consumptive water use of
crops,  vegetation,  or  woodland being  considered.  The type of climate
will determine the impact that aspect  has on  site suitability.


The USGS publishes topographic maps for  most  areas  in  the United States.
These maps  usually  have  scales of 1:24 000  (7.5 minute  series)   or
1:62 500  (15 minute series),  and  they  are  suitable for determining the
slope and elevation of a region for a  project in the planning stage.
Examination  of  topographic   features   should   not   be  limited  to the
potential site.  Adjacent  topography  should  be  evaluated for its effects
on  the  site,  particularly   with  respect   to  drainage  and  areas of
potential  erosion.   Adjacent land characteristics  to be identified are
                                   3-17

-------
those   that   may   potentially    (1)   add   stormwater  runoff to  the  site,
(2)   back up  water onto the site,    (3)   provide   relief   drainage,    or
(4)   cause the appearance  of groundwater  seeps.
                                       TABLE 3-5

                             SITE SELECTION GUIDELINES
    Characteristic
 Land treatment
process affected
                                                          Effect
   Soil permeability   Overland flow
                  High permeability soils are more suitable to
                  other processes.
                      Rapid infiltration  Application rates increase with permeability.
                      and slow rate
   Potential ground-
   water pollution
   Groundwater storage
   and recovery
Rapid  infiltration
and slow rate
Rapid  infiltration
   Existing  land uses   All processes
   Future land use


   Size of site



   Flooding hazard

   Slope
All  processes


All  processes



All  processes

All  processes


Rapid  infiltration
Overland flow
Affected by the  (1) proximity of the site to a
potential potable aquifer,  (2) presence of an
aquiclude, (3) direction of groundwater flow,
and  (4) degree of groundwater recovery by wells
or underdrains.

Capability for storing percolated water and
recovery by wells or underdrains is based on
aquifer depth, permeability, aquiclude con-
tinuity, effective treatment depth, and ability
to contain the recharge mound within the
desired area.

Involves the occurrence and nature of
conflicting land use.

Future urban development may affect the ability
to expand the system.

If there are a number of small parcels, it is
often difficult  to control  the needed area and
implement the plan.

May  exclude or limit site use.

Steep slopes may (1) increase capital expenditures
for  earthwork, and (2) increase the erosion hazard
during wet weather.

Steep slopes often affect groundwater flow pattern.

Steep slopes reduce the travel time over the
treatment area and treatment efficiency.  Flat
land may require extensive  earthwork to create
slopes.
            3.5.3.1   Slope
Excessive  slope   is   an undesirable  characteristic for land application
because   (1)  it   increases   the   amount   of runoff and  erosion  that  will
occur,   (2)  it  may   lead   to  unstable  soil  conditions when the soil  is
saturated,   and   (3)  it  makes   crop   cultivation   difficult or, in  some
                                        3-18

-------
cases,  impossible.  Criteria for maximum slope will  depend,  in part,  on
both  the  amount  of  land with moderate slopes (less than 10%) that is
available  and  the  land  treatment process.   Successful  agriculturally
related  systems  using  slopes  of  15%  or  more and silviculture type
systems on wooded slopes of up to 40% have been reported L13J.
The  system  configuration  and earthwork requirements, particularly for
overland  flow  and  rapid infiltration treatment, are important factors
that will determine the maximum slopes permissible for a potential  site.
If  rolling  terrain is to be used for cultivated agriculture,  the  slope
should  not  exceed about 15%.  Grass and forage crops can be adapted to
steeper  slopes.   Relatively flat land is normally required for surface
irrigation,  although  contour furrows have been used on slopes as  steep
as 5,%.
For  rapid infiltration, the primary topographic concern is that lateral
water  movement  be controlled so that percolation rates of lower basins
are  not affected.  At Westby, Wisconsin, basins have been terraced into
a  5%  sloping  hillside,  but there are no underdrains, and the lateral
movement   of  water  from  the  upper  basins  reportedly  affects  the
percolation rates in the lower basins.


For  overland  flow,  the  primary  requirement  is  that  the  existing
topography  be  such  that  terrace  slopes  of  2 to  8%  can be formed
economically.   The  cost  and  impact of the earthwork required are the
major constraints.
          3.5.3.2  Relief
Relief  is  the  relative  elevation or elevation difference between one
part  of  the land treatment system and another.  Relief and terrain are
interrelated  as  they  affect the economics of pumping wastewater.   The
pumping cost is the principal annual operation cost when large elevation
differences  exist  between the wastewater source and the land treatment
site,  reuse  location,  or  discharge point.  This cost must be weighed
against  the  cost  of constructing gravity conveyance to sites that may
have  greater  distances  between system components but favorable relief
characteristics.
For   silviculture   (where  sprinkler  irrigation  of  forest  land  is
considered),  more  liberal  relief  and  slope  tolerances are possible
because  the  nature  of  the root system, forest litter, and vegetation
offer resistance to direct surface runoff and resulting erosion.
                                  3-19

-------
          3.5=3.3  Susceptibility to Flooding


Location of land treatment systems within a  flood plain  can  be either  an
asset  or  a  liability, depending on the approach taken to  planning and
design.   Flood  prone  areas  may  be undesirable because of the  highly
variable  drainage  characteristics  usually  encountered and potential
flood damage to the physical  components of the treatment system.   On the
other hand, flood plains, alluvial deposits, and  delta formations  may  be
the  only  deep  soils  available  in the area.   With careful  design and
choice  of  application  techniques,  a  land  treatment  system can be  an
integral  part of a flood plain management plan.   The flooding hazard  of
a  potential  site should be evaluated with  respect to both  the severity
of floods that could occur and the extent of the  area flooded.
The  extent  of flood protection built into a  land treatment system  will
depend on local conditions.  In some cases, it may be preferred to allow
the  site  to flood as needed and provide the  protection  through offsite
storage.    Further,   flood   plains  are  generally  unacceptable   for
construction   of   dwellings   or  commercial   buildings,   offering  an
opportunity  for  imaginative uses of land treatment systems.   It should
be  noted  that crops can be grown in flood plains if the infrequency of
floods makes it economical  to farm.
Descriptions  of  severe floods that have occurred in the United States,
and  summaries of all notable floods of each year, are published as  USGS
Water  Supply  Papers.   Maps  of  certain  localities  showing the  area
inundated  in  past  floods  are  published  as Hydrologic Investigation
Atlases  by  the  USGS.  More recent maps of flood prone areas have  been
produced  by  the  USGS  in  many  areas  of  the country as part of the
"Uniform  National  Program  for  Managing  Flood Losses."  The maps are
based  on  standard  7.5  minute  (1:24 000) topographic sheets; and,  by
means  of  overprint  in black and white, they identify those areas  that
have  a  1  in  100  chance  of  being  inundated  in  any  given year.
Additionally, other detailed flood information is usually available  from
local  offices  of  the  U.S.  Corps  of Engineers and the flood control
districts that deal with such problems firsthand.
     3.5.4  Soils
The  soil  at  a  potential  site  should  be identified in terms of its
hydraulic,  physical,  and chemical  characteristics.   Important physical
characteristics  include  texture, structure, and soil  depth.   Important
hydraulic  characteristics  are  infiltration  rate  and   permeability.
Chemical characteristics  that  may  be  important  include  pH,  cation
exchange  capacity,  nutrient  levels, and the adsorption and filtration
capabilities for various inorganic ions.
                                  3-20

-------
Information on soil properties can be obtained from several sources, but
the  SCS  soil surveys are the primary source.  Well logs can also offer
additional  data  on  soils  and  geology.   Soil  surveys will normally
provide  soil  maps  delineating  the apparent boundaries of soil series
with  their  surface texture.  A written description of each soil series
provides   limited   information  on  chemical  properties,  engineering
applications, interpretive and management information, slopes, drainage,
erosion  potentials,  and  general  suitability  for most kinds of crops
grown   in   the  particular   area.   Additional  information  on  soil
characteristics  and  information  regarding  the  availability  of soil
surveys  can  be  obtained directly from the SCS.  The SCS serves as the
coordinating  agency  for  the  National Cooperative Soil Survey, and as
such,  cooperates  with  other  government  agencies,  universities, and
agricultural  extension  services  in  obtaining  and  distributing soil
survey information.
          3.5.4.1  Soil Physical Characteristics
The  physical  properties of texture and structure are important because
of  their  effect  on  hydraulic  properties.  Soil textural classes are
defined  on the basis of the relative percentage of the three classes of
particle  size—sand, silt, and clay.  Sand particles range in size from
2.0  mm  to  0.05 mm; silt particles range from 0.05 mm to 0.002 mm; and
particles  smaller  than  0.002  mm  are  clay.   From the particle size
distribution,  the  textural  class can be determined using the textural
triangle  shown  in  Figure  3-7.   Terms commonly used to describe soil
texture  and  the relationship to textural class names as established by
the SCS are listed in Table 3-6.
Fine-textured  soils  do  not drain well and retain large percentages of
water  for  long  periods of time.  As a result, crop management is more
difficult  than  with  more  freely  drained  soils such as loamy soils.
Fine-textured  soils are generally best suited to overland flow systems.
Medium-textured soils exhibit the best balance for wastewater renovation
and  drainage.   Loamy  (medium texture) soils are generally best suited
for slow rate systems (crop irrigation).


Coarse-textured soils (sandy soils) can accept large quantities of water
and  do  not  retain  moisture very long.  This feature is important for
crops  that  cannot  withstand  prolonged  submergence or saturated root
zones.   Soil  structure  refers  to  the aggregation of individual soil
particles.   If  these aggregates resist disintegration when the soil is
wetted  or  tilled,  it  is  well  structured.  The large pores in well-
structured soils  conduct  water  and  air, making well-structured soils
desirable for infiltration.
Adequate  soil depth is important for root development, for retention of
wastewater  components  on  soil  particles,  and  for bacterial action.
                                  3-21

-------
                            FIGURE 3-7

             PROPORTIONS OF SAND, SILT, AND CLAY  IN
              THE  BASIC SOIL-TEXTURAL CLASSES  [14]
                             too
10
                              PERCENT SAND

           U.S  STANDARD SIEVE NUMBERS

               10  2040 60    200
I
\


L
1 1 i i i in M i
SAHD
er oc
UJ ^
>• 0
CJ
UJ
CO
QC
^
0
o
i i
z
a
UJ
Z
UJ


at •*.
UJ —
> u.


SILT



CLAY


1 III III II
                ^  —   in   in
                                o   o
                            GRA IN SIZE, mm
                                3-22

-------
Plant roots  can  extract water from depths  ranging from 1 to 9 ft (0.3 to
2.7 m) or more.   Retention of wastewater components,  such as phosphorus,
heavy metals,  and viruses, is a function of  residence time of wastewater
in  the  soil  and  the  degree of contact between soil  colloids and the
wastewater components.


                                TABLE 3-6

             SOIL TEXTURAL CLASSES AND GENERAL  TERMINOLOGY
                     USED IN SOIL DESCRIPTIONS  [15]
                      General terms
                                          Basic soil textural
                Common name      Texture          class names


                Sandy soils   Coarse          {Samy sand
                            Moderately coarse          ]oam
                Loamy soils   Medium
Very fine sandy loam
Loam
Silt loam
Silt
                                           !Clay loam
                                           Sandy clay loam
                                           Silty clay loam

                                          iSandy clay
                 Clayey soils  Fine           {Silty clay
                                          'Clay
The  type   of   land  treatment  system   being   considered will determine
whether soil depth is adequate.  The minimum soil  depth for most systems
that  rely  on  infiltration  (rapid  infiltration and   slow    rate)   is
about 3 to  5 ft (1.0 to 1.5 m).  Soil depths of 1  to 2 ft (0.3 to 0.6  m)
can  support   grass  or  turf.  Overland flow  systems require sufficient
soil  depth to form slopes that are uniform and to maintain a vegetative
cover.
          3.5.4.2   Soil  Hydraulic Properties


Drainage of water  within the soil depends  on  texture, structure, and the
absence of subsurface constraints to  the flow of water.  An example of  a
vertical  constraint  would  be  an   impermeable clay, hardpan,  or rock
strata  underlaying  a  sandy  soil.   The  lateral  transmissibility and
percolation   rates  may limit the application rate unless they are equal
to  or  higher   than  the infiltration rate.   For high rate systems that
depend  largely  on vertical water movement,  the permeability of the most
                                   3-23

-------
restricting  layer  in  the  upper  several  feet   of   soil will  usually
determine the maximum hydraulic loading.


The  most recent permeability class definitions developed  by  the  SCS  are
shown  in  Table 3-7.    Soil permeabilities other  than the values  shown
in  Table  3-7   (for  the   respective permeability class) may  appear in
soil  literature  depending  on  the  age  of  the  document  and  local
variations  in  interpretation.   The  soil permeability ranges normally
associated  with each land treatment process are compared  along with  the
corresponding permeability and textural class in Table  3-8.
                                TABLE 3-7

              PERMEABILITY CLASSES FOR SATURATED SOIL  [15]
                       Soil permeability,
                            in./h            Class
<0.06
0.06 to 0.2
0.2 to 0.6
0.6 to 2.0
2.0 to 6.0
6.0 to 20
>20
Very slow
Slow
Moderately slow
Moderate
Moderately rapid
Rapid
Very rapid
                       1  in./h = 2.54 cm/h
                                TABLE 3-8

                TYPICAL SOIL PERMEABILITIES AND TEXTURAL
                  CLASSES FOR LAND TREATMENT PROCESSES


Soil permeability
range, in./h
Permeability
class range
Textural
class range
Unified Soil
Classification [16]
Principal
Slow rate
0.06-20
Moderately slow to
moderately rapid
Clay loams to
sandy loams
GM-d, SM-d, ML,
OL, MH, PT
processes
Rapid
infiltration
2.0
Rapid
Sapds and
sandy loams
GW, GP, SW,
SP

Overland
flow'
0.2
Slow
Clays and
clay loams
GM-u, GC,
SM-u, SC,
CL, OL, CH, OH
Other pr
Wetlands
0.06-2.0
Slow to
moderate
Clay loams
to silt loams

ocesses
Subsurface
0.2-20.0
Moderately
slow to rapid
Clay loams
to sands

                                  3-24

-------
          3.5.4.3  Soil Chemical Characteristics
The  balance  of  chemical  constituents  in  soil  is important to plant
growth  and  wastewater  renovation.   The  mechanisms  of  retention of
certain  constituents  by the soil are discussed in Appendixes A through
E.   Chemical  properties  of  the  soil should be  known by the engineer
prior to design for the purpose of determining changes in soil chemistry
that  could  occur  during  operation.   Some  of the indicators of soil
conditions   are   pH,   salinity,   cation   exchange  capacity  (CEC),
exchangeable   sodium   percentage   (ESP),   percent  base  saturation,
nutrients,   and   metals.    Detailed   discussion  of  these  chemical
characteristics is deferred to Appendix F.


     3.5.5  Geology
Geologic formations and discontinuities that might cause unexpected flow
patterns of applied wastwater to the groundwater should be identified in
the  planning stages of a land treatment system.  If the underlying rock
is  fractured  or  crevassed  like limestone, percolating wastewater may
shortcircuit  to  the  groundwater,  thus  receiving  less  than  proper
treatment  because  of  reduced  residence time in the soil.  Similarly,
perched  water  tables  above  the  normal  groundwater  can result from
impermeable  or  semi permeable  layers  of  rock, clay, or hardpan, thus
reducing  the  effective renovative depth.  Permanent groundwater should
be  distinguished  from  localized perched groundwater conditions.   Both
the  reason  for  and the direction of movement of a perched groundwater
are important geohydrologic factors of a site.


Geologic  discontinuities,  such  as  faults  and  intrusions, should be
evaluated  for  their  effect  on  groundwater  occurrence, influence on
quantity, and direction of movement.  The USGS and many state geological
surveys  have  completed  studies  and  maps  indicating  the effects of
geologic  formations on groundwater occurrence and movement.  Water well
logs  can  also  provide  local,  detailed  information.   A groundwater
geologist   familiar   with   local   conditions  can  provide  valuable
information by identifying geologic features that may affect groundwater
movement at a particular site.


     3.5.6  Climate
An   evaluation  of  climatic  factors,  such  as  precipitation,  evapo-
transpiration, temperature,  and  wind,  is used in the determination of
the  (1) water  balance, (2) length of the growing season, (3) number of
days  when  the  system  cannot  be  operated,  (4) the storage capacity
requirement, and (5) the amount of stormwater runoff to be expected.
                                 3-25

-------
          3.5.6.1  Climatic Data and Its Use
Sufficient climatic data are generally available for most locations from
three  publications  of the National  Oceanic and Atmospheric Administra-
tion (NOAA - formerly the U.S. Weather Bureau).
The  Monthly Summary of Climatic Data provides  basic data,  such as total
precipitation,  maximum and minimum temperatures,  and relative humidity,
for  each  day  of  the month for every weather station in  a given area.
Evaporation data are also given where available.


The  Climatic Summary of the United States provides 10 year summaries of
data  for  the  same stations in the same given areas.  This form of the
data  is convenient for use in most of the evaluations that must be made
and includes:

     •    Total precipitation for each month of the 10 year period

     •    Total snowfall for each month of the  period

     •    Mean number of days with precipitation exceeding  0.10 and 0.50
          in. (0.25 and 1.3 cm) for each month

     •    Mean temperature for each month of the period

     •    Mean daily maximum and minimum temperatures for each month

     •    Mean  number  of  days per month with temperature less than or
          equal  to  32°F  (0°C),  and  greater  than  or  equal  to 90°F
          (32.5UC)
Local  Climatological  Data, an annual  summary  with comparative data,  is
published  for  a  relatively  small   number of major weather stations.
Among the most useful data contained  in the publication are the normals,
means,  and  extremes  which  are based on all  data for that station,  on
record  to  date.   To use such data,  correlation may be required with a
station reasonably close to the site.
Climatic  data  should be subjected to a frequency analysis to determine
the  expected  worst  conditions  for  a  given return period.  The data
analyses are summarized in Table 3-9.


          3.5.6.2  Climatic Considerations for Crops


The  consumptive  use  by plants is in direct relation to the climate of
the area.  Consumptive use or evapotranspiration is the total water used
                                   3-26

-------
in  transpiration,   stored in plant tissue, and evaporated from adjacent
soil  [17].  The  consumptive use varies with the  type  of crop,  humidity,
air  temperature,   length  of  growing  season,   and wind velocity.  The
amount of water lost by evapotranspiration can be estimated from the pan
evaporation  data  supplied  by NOAA in the vicinity of the site or from
theoretical methods (see Appendix F).
                                 TABLE 3-9

                       SUMMARY OF CLIMATIC ANALYSES
Factor Data required
Precipitation Annual average.
Analysis
Frequency
analysis.
in.
/yr
Water
Use
balance
              maximum, minimum

 Rainfall storm  Intensity, duration  Frequency analysis, in./d  Runoff estimate

                              Frost free period, d
Temperature


Wind
Days with average
below freezing

Velocity and
direction
Storage, treatment efficiency,
crop growing season

Cessation of sprinkling
 1 in. = 2.54 cm
The length  of the growing season affects  the  amount of water used by the
crop.  The  length of the growing season for perennial  crops is generally
the  period beginning when the maximum daily  temperature stays above the
freezing  point for an extended period of days,  and continues throughout
the  season  despite  later  freezes  LI7].    This  period is related to
latitude  and  hours of sunlight as well  as to the net flow of energy or
radiation   into  and  out  of  the  soil.  A  limited growing season will
require  long  periods  of storage or alternative methods of disposal in
winter.
      3.5.7   Surface Water Hydrology  and  Quality
           3.5.7.1  Hydrology
Surface  water  hydrology  is  of   interest  in land treatment processes
mostly   because of the runoff of stormwater.   Considerations relating  to
surface runoff control apply to both  slow rate and overland flow.  Rapid
infiltration processes are designed for no runoff.


The  control  of stormwater runoff both onto and off a land treatment  site
must  be  considered.   First, the  facilities constructed as part  of the
treatment  system  must  be  protected  against erosion and washout  from
                                   3-27

-------
extreme  storm  events.    For  example,   where   earthen  ditches  and/or
terraces  are  used,   erosion  control   from  stormwater  runoff must be
provided.  The degree of control  of runoff  to prevent the destruction of
the  physical  system  should  be  based on  the  economics of replacing
equipment  and  structures.   There is no standard  extreme storm event in
the design of drainage and runoff collection  systems, although a 10  year
return event is suggested as a minimum.


          3.5.7.2  Quality
The  need  to  control  surface runoff resulting  from stormwater depends
mainly  on  the  expected  quality  of the runoff relative to the normal
discharge  requirements  to  a  local   body  of  water.    Runoff quality
resulting from storms at land treatment sites is  essentially unknown for
most  constituents.   However, to give some perspective  to the magnitude
of  nitrogen  and  phosphorus  concentrations  in  runoff  from  various
agricultural and rural areas, and as an approach  to solving the problem,
selected  data  from agricultural stormwater runoff studies are given in
Table 3-10.
It  is  important  to note that the research work reported in Table 3-10
was  aimed  primarily  at  fertilizing  practice  and cultivation versus
noncultivation  as related to nutrient losses.   Nevertheless, these data
suggest that it is advisable to provide some form of sediment removal  at
land  treatment  sites  before  allowing  the  remaining runoff water to
escape.   Based  on  the experimental  work in Wisconsin 121J, this would
greatly  reduce  the  nutrient  losses  from  the site.  Methods used to
minimize  sediment and nutrient loss include (1) contour planting versus
straight-row  planting,  and  (2)  incorporation  of  plant  residues to
increase  organic  matter  in  the  soil.    In each research study, many
additional  factors  that  affect erosion  losses were presented, and the
interested reader should consult the literature.
More recently,  Loehr [22] has compiled runoff quality data from various
nonpoint sources.    Ranges of values for concentrations of constituents
in  agricultural  runoff resulting from precipitation and the  potential
yield per unit area of these constituents are listed in Table 3-11.
Runoff  quality  estimates  derived from data in Table  3-11  are  to  be
considered  preliminary  in  nature  because  of  variations in sampling
methods,   analytical  methods,  field  conditions,  and  meteorological
constraints.   The  order  of  magnitude  of the characteristics and the
differences  between  sources  are  more  significant  than  the values.
Adherence  to established agricultural practices for erosion control and
environmental protection will limit adverse runoff impacts.
                                  3-28

-------
                               TABLE 3-10

           AVERAGE VALUES OF NITROGEN AND PHOSPHORUS MEASURED
                IN AGRICULTURAL STORMWATER RUNOFF STUDIES
Location
•'ind si te
description Management practice
North Carolina Heavily fertilized,
[18] uncultivated
Lightly fertilized,
uncultivated
Ithaca, H.Y. Highly fertilized
(corn, beans, „ , ^ , . . ., . .
wheat) [19] Moderately fertilnzed
Ontario (marsh) Fertilized and cultivated
Unfertilized and uncultivated
Wisconsin Fertilized plowed surface
(pilot plots, l. in sediment
oat stubble) 2. In water
[21]
Unfertilized plowed surface
1 . In sediment
2. In water
a. Ammonia plus nitrate nitrogen only.
b. Inorganic phosphorus only.
c. Nitrate plus nitrite nitrogen only.
d. Organic nitrogen from soil sediment accounted
nitrogen. Runoff occurred from 1 h of rain at
after a similar rain event.
Total
nitrogen ,
mg/L
4.60
4.60
1.60
6.17a
1.70a
1.88C
0.05C
81. 8d
2.8
84.6
75.2
0.7
75.9



for 90+% of
2.5 in./h,
Total
phosphorus,
mg/L
0.10
0.10
0.08
0.26b
0.12
0.67
0.17
0.88
0.49
T737
0.33
0.1
0.43



all
24 h
          1  in./h = 2.54 cm/h
     3.5.8  Groundwater Hydrology and Quality
Collection  and  analysis of available data on groundwater hydrology and
quality  are  essential  to planning and feasibility studies.  Desirable
information  includes  soil  surveys, geologic and groundwater resources
surveys,   well  drilling  logs,  groundwater  level  measurements,  and
chemical  analysis of the groundwater.  Numerous federal, state, county,
and city agencies have this type of information as well as universities,
professional   and   technical  societies,  and  private  concerns  with
groundwater-related  interests.   Particularly good sources are the USGS
at  the  federal  level,  state  water resources departments, and county
water conservation and flood control districts.
                                   3-29

-------
                                TABLE 3-11

      SUMMARY  OF  AGRICULTURAL NONPOINT SOURCES CHARACTERISTICS  [22J
Source
Preciptation
Forested land
Rangeland
Agricultural
cropland
Land receiving
manure
Irrigation tile
drainage, western
United States
Surface flow
Subsurface
drainage
Cropland tile
drainage
Seepage from
stacked manure
Feedlot runoff
Concentration, mg/L
BOD NOs-N Total N
12-13 0.14-1.1 1.2-0.04
	 0.1-1 .3 0.3-1 8

7 0.4 9
04-1.5 0.6-2.2
1 8-19 2.1-19
	 10-25
10 300-13 800 	 1 800-2 350
1 000-11 000 10-23 920-2 100
Area yield rate, lb/acre-yr
Total P
0.02-0.04
0.01-0.11
0.02-1.7
0.2-0.4
0.1-0.3
0.02-0.7
190-280
290-360
BOD N03-N Total N
	 1.3-3.7 5-9
	 0.6-7.9 3-12
06
	 0 1-12
	 3.6-12
	 3-24
.... 74 38-166
	 0.3-12

1 390 . 890-1 430

Total P
0.04-0.05
0.03-0.8
0.07
0.05-2.6
0.7-2.6
0.9-4.0
3-9
0.009-0.3
9-550
   Note: Data do not reflect the extreme ranges caused by improper waste management or extreme stonoi
       conditions.

   1 lb/acre-yr = 1.12 kg/ha-yr
          3.5.8.1   Hydrology


A  knowledge   of   the   regional   groundwater  conditions  is  particularly
important for   potential   rapid  infiltration  and  slow rate    sites.
Overland flow  will  not  usually  require  an  extensive hydrogeologic
investigation.     Sufficient   removal   of  pollutants  in   the   applied
wastewater  before  reaching  a   permanent  groundwater   resource is the
primary  concern.  The  depth to  groundwater and its seasonal  fluctuation
are  a  measure  of  the aeration zone and the degree of  renovation  that
will take place.
When  several   layers   of  stratified  groundwater underlie  a  particular
site,  the  occurrence   of the vertical  leakage between  layers should be
evaluated.    Direction   and  rate  of   groundwater  flow   and  aquifer
permeability  together   with  groundwater depth are useful in  predicting
the  effect of  applied  wastewater on the groundwater regime.   The extent
of recharge mounding, interconnection of aquifers, perched water tables,
                                    3-30

-------
the  potential  for  surfacing groundwater, and the design of monitoring
and withdrawal wells are dependent on groundwater flow data.


Much  of  the data required for groundwater evaluation may be determined
through  use of existing wells.  Wells that could be used for monitoring
should be listed and their relative location described.  Historical  data
on  quality,  water  levels, and quantities pumped from the operation of
existing wells may be of value.  Such data include seasonal groundwater-
level variations,  as  well  as  variations over a period of years.   The
USGS  maintains  a  network of about 15 800 observation wells to monitor
water  levels  nationwide.   Records  of  about 3 500 of these wells are
published  in  Water-Supply  Paper  Series, "Groundwater - Levels in the
United  States."   Many  local,  regional,  and  state  agencies compile
drillers'  boring  logs  that are also valuable for defining groundwater
hydrology.


          3.5.8.2  Groundwater Quality
Land  treatment of wastewater can provide an alternative to discharge of
conventionally  treated  wastewater.  However,  the  adverse  impact  of
percolated  wastewater  on  the  quality of the groundwater must also be
considered.  Existing  groundwater  quality  should  be  determined  and
compared  to  quality  standards  for  its  current   or   intended use.
Groundwater  classifications  are  discussed  in  Section   5.1.1.    The
expected  quality  of  the  renovated wastewater can then be compared to
determine  which  constituents in the renovated water might be limiting.
The   USGS   "Groundwater   Data  Network"  monitors  water  quality  in
observation  wells across the country.  In addition, the USGS undertakes
project  investigations or areal groundwater studies in cooperation with
local, state, or other federal agencies to appraise groundwater quality.
Such reports may provide a large part of the needed groundwater data.


3.6  Other Planning Considerations
Land   treatment  systems  make  use  of  existing  natural   conditions;
therefore,  a  thorough  knowledge  of  all  aspects of any given site is
necessary for a successful  design.  Most features common to all  sites or
projects  have  been discussed briefly in the preceding sections.   There
are   also  governmental   features  or  planning  factors  that  may  be
indirectly related to land treatment studies.  Some of these factors are
presented in this section,  including:
     •    Water rights

     •    Governmental programs

     •    Land use
                                   3-31

-------
     •    Environmental  setting

     t    Social  and economic aspects


     3.6.1  Water Rights
On  the  basis  of  water rights considerations,  the implementation  of  a
land   treatment   system  may  involve  a   change   in   water  use   from
nonconsumptive  (passing  flow through a  treatment  plant with subsequent
discharge)  to  consumptive.    This  change  can  interfere with the water
rights of downstream or senior claims to  the water  as the source  of  flow
is  depleted  when the discharge is not returned  to its  original  channel
[23J.
Water  rights  problems  tend to arise in water-short or fully  allocated
areas,  yet the existence of a market for reclaimed water in  these  areas
will  aid in the cost effectiveness and acceptability of land treatment.
On a national level, these areas are shown in  Figure 3-8.


Most  riparian  (land  ownership)   rights  are  in  effect east of  the
Mississippi  River, and most appropriative (permit system) rights are in
effect  west of the Mississippi River, as shown  in  Figure 3-8  [24],    A
legal  distinction  is made between discharges to  a receiving water in a
well-defined  channel or basin (natural watercourse), superficial waters
not  in  a channel or basin (surface waters),  and  underground waters  not
in  a  well-defined channel or basin (percolating  or groundwaters)  [24].
A  guide  in determining whether certain land  treatment alternatives  may
involve water rights problems is presented in  Table 3-12.   The  intention
here  is  not  to  imply  that  some alternatives  will  have problems  and
others will no~t, but merely to guide the planner or engineer  through  the
preliminary screening of alternatives.


          3.6.1.1  Riparian Rights


According  to  the Riparian Doctrine, anyone owning land adjacent to, or
underlying, a natural watercourse has the right  to use, but not consume,
the  water.   Within  this  theory have arisen two subtheories  ("natural
flow allocation" and "reasonable use") that affect the manner in which a
riparian  right  can  be  executed.   In natural flow,  the landowner  can
diminish  neither  the  quantity  nor  the  quality  of the water before
returning  it to the watercourse.   Beyond minimum  consumptive uses, such
as drinking, bathing, or cooking,  this right is  very restrictive, and it
gave rise to the reasonable use theory.  Water under natural  flow can be
withdrawn for a "natural," riparian, or nonriparian use.  Reasonable  use
requires  that  the  water  be  used for a legal and beneficial purpose.
Because  the  water  right under riparian theory is closely aligned with
the  concept  of land ownership, the rights to water ownership  pass with
sale of the land [25].
                                  3-32

-------
                                                             FIGURE 3-8
                          DOMINANT WATER  RIGHTS DOCTRINES AND AREAS OF WATER SURPLUS  OR  DEFICIENCY [24]
GO
I
CO
to
               APPROPRIATE AND

                LAND OWNERSHIP
                      ss&isJisssssfiss?
                     RIGHTS
DOMINANTLY
  APPROPRIATE
       , RIGHTS
LAND OWNERSHIP
    RIGHT
                                                           APPROPRIATE

                                                              AND LAND

                                                              OWNERSHI
                                                               RIGHTS
                            AREAS OF WATER SURPLUS


                            AREAS OF WATER DEFICIENCY

-------
                                  TABLE 3-12
                  POTENTIAL WATER  RIGHTS PROBLEMS FOR  LAND
                            TREATMENT ALTERNATIVES
                                       Land treatment process
        Water definition and
        water rights theory
               Slow rate
  Rapid
infiltration
Overland flow
        Natural watercourses

         Riparian          Unlikely    Unlikely

         Appropriative      Likely'5     Likely'5
         Combination
               Likelyb     Likely5
           Unlikely

           Depends on  location of discharge
           from collection ditch

           Depends on  location of discharge
           from collection ditch
Surface waters
Riparian
Appropriative
Combination
Percolating
or groundwaters
Riparian
Appropriative
Combination

Unlikely
Unlikely
Unlikely

Unlikely
Likely
Likely

Unlikely
Unlikely
Unlikely

Possible
Likely
Likely

Likely0
Likely^
Likelyc

Unlikely
Unlikely
Unlikely
        a.  For existing conditions and alternatives formulation stage of the planning
           process only.  It is also assumed that the appropriative situations are
           water-short or over-appropriated.

        b.  If effluent was formerly discharged to stream.
        c.
If collection/discharge ditch crosses other properties to
natural watercourse.
           3.6.1.2  Appropriative  Rights
Appropriative   rights  tended to  be enacted  by statute and  defined in  the
courts  on  a   case-by-case  basis.    As a  result,  wide variations exist
among  the 19 western states that recognize  such rights.  In  general,  the
basic  principles of appropriative rights theory are:   (1)  first in time,
first   in  right for the water,  and (2) subsequent  appropriations cannot
diminish  the   quantity   or quality of a senior right.   Usually, permits
are   required   to  establish  the  right to appropriative  water, and  the
water  thus appropriated  must also be put to a beneficial use.   Rights to
appropriated   water  are not connected with land ownership.  They may be
bought,  sold,  exchanged, or transferred wholly or in  part  [26],
                                      3-34

-------
          3.6.1.3  Combination Rights
Many  states  recognize  a  combination  of  riparian  and appropriative
rights.   This  dual-rights  system  has  developed  in states that have
water-short  and  water-surplus  areas  within  their  borders.  In such
cases, the appropriative theory is usually the predominant one L24J.
          3.6.1.4  Types of Waters
For  legal  purposes,  states  have  divided  waters  into  three types:
natural  watercourses,  surface  water,  and percolating (groundwaters).
These  classifications are arbitrary and are not based on any scientific
or  empirical rating system but their definition does affect the type of
legal problems that may be encountered in land treatment.
               3.6.1.4.1  Natural Watercourse
A  natural  watercourse is one in which water flows in a defined channel
either  on or below the earth's surface.  This definition includes lakes
and estuaries and intermittent as well as perennial streams.


The  major  legal  problem  that  could be expected in both riparian and
appropriative  states  would  involve the diversion of what was a direct
discharge   with  the  subsequent  reduction  in  flow  to  the  natural
watercourse.   If  the  watercourse  in  question  is  near  or at over-
appropriation, junior  water users who feel  that a reduction in flow may
impair  their  reasonable  use  of  the water may seek administrative or
judicial relief.
In  a  riparian  state,  the  diversion  of  a  discharge  that  was not
originally  a  part  of a stream should not be cause for legal action by
downstream users under natural flow theory.
For  appropriative  rights  states, the risk of legal action against the
diversion  is  easier  to  analyze.  If the conditions of the stream are
such  that  the  diversion would threaten the quantity or quality of the
appropriated water of a downstream user, the damaged party has cause for
legal  action  against  the diverter.  This action may be injunctive,  in
which  the  diverter  is  prevented  from  affecting  the  diversion,  or
monetary,  in  which  the  diverter  would be required to compensate for
damages  caused  by  his  diversion.   If  the  stream in dispute is not
already  over-appropriated  (as is the case in many western streams),  or
if  the  area  is  not water short, it is unlikely that damages could be
proved as a result of the diversion.
                                  3-35

-------
               3.6.1.4.2  Surface Water
A  surface  water  is  the legal  term for water  not contained in  a  well-
defined basin  or  channel,  i.e.,   rainfall   or  snowmelt directly on  a
parcel  of  land.   Such  waters   belong  to the  landowner, but he cannot
collect  and  discharge  them  across  adjoining  properties without the
consent  of  the owners of those  lands.   For surface water rights,  there
is little difference between riparian and appropriative states.
If  any  of  the  land  treatment  alternatives   being considered by  the
planner  or  engineer  require  that the renovated water cross another's
property, the granting of a drainage or utility  easement across the land
to  the  natural  watercourse or final  user is a necessity in all cases.
The   cost   of  such  an  easement  must  be considered  in  the cost-
effectiveness analysis.


               3.6.1.4.3  Percolating Waters (Groundwaters)


Problems  with water rights could arise from two areas:   (1)  the rise in
groundwater  caused  by  the  land treatment method may damage adjoining
lands,  or  there  may  be  some  interference   with the subsurface flow
patterns;  and  (2) if trace contaminants appear in wells of  other water
rights  holders, they may perceive a damage as a result of altered water
quality.
In  riparian states, the claim of damages would require that a landowner
prove  that  he  overlies  the  same  source  of  the groundwater as the
owner/operator.   If  the  alleged  damages  are not caused by negligent
operation  of  the  treatment  site,  or  in  a way that is deliberately
harmful  to  the  adjoining  landowners,  it  is doubtful  that they have
sufficient cause for legal action.


For  appropriative  theory  states,  the  question of an increase in the
level  or  volume  of  a groundwater should cause no problems because no
one's appropriative right would be threatened.


          3.6.1.5  Other Water Rights Considerations


In  some  states,  basin  authorities or water/irrigation districts have
regulations  against  the transfer of water outside their jurisdictional
boundaries.   In the western states particularly, the right to divert or
use water does not carry with it the right to store such water.
                                   3-36

-------
The  right  to  water  salvaged  from  imported  water  that has run  off
irrigated lands is also not automatic.   The rights in both cases must be
specifically  obtained  or  at  least must be assured by precedent legal
action.
          3.6.1.6  Sources of Information
The data contained in this section may be sufficient for a small  system,
but  for  larger  systems and in problem areas,  the watermaster or water
rights  engineer  at the state or local  level  should be consulted.  Some
states  either  have  no  records or carry unenforceable rights in their
records  L27],  so that further investigation  will  be necessary if doubt
remains.   An  excellent  reference  is  the  National   Water Commission
publication,  A  Summary-Digest  of  State Water Laws available from the
Commission  L28].   Although  summaries  of  precedent  rulings  are not
guarantees, they may clarify the situation if  similar cases can be found
L23,  24,  27,  29, 30].  Lastly, if problems  arise, the assistance of a
water rights attorney is warranted.


          3.6.1.7  Resolving Water Rights Problems


To  resolve  water  rights problems, the planner should first attempt to
define  the  water  rights  setting  that  could  affect the fate of any
renovated  water  and  then be aware,of the quantity and priority of all
rights  in  the district or basin.  The next step is to define the water
rights  constraints  for  all  alternatives.  Once  the candidate systems
have been selected, the point of discharge, availability and quantity of
discharge,  and  modifications to existing practices should be examined.
If  problems  are  likely with any of the feasible  alternatives,  a water
rights  attorney  should  be  consulted to define more closely the legal
constraints  on  the  alternatives  and  to  define the owner/operator's
rights  and  responsibilities.   If  the owner's rights to the renovated
water  can  be  established,  he  can  now  trade  those rights with any
potentially  damaged  senior rights or use the revenues from sale of the
water to offset possible damage claims.


     3.6.2  Governmental Programs


The  most  important  federal programs that should  be considered in land
treatment,  in  addition to the EPA Construction Grants Program,  are the
Soil Conservation Service, Bureau of Reclamation, and U.S. Army Corps of
Engineers  with  their reclamation/irrigation  programs being of greatest
interest.    However,   despite   the   national policy  of  wastewater
reclamation  [31J  and the National Water Commission's recommendation to
exchange   sewage  effluent  with  potable  water  now  being  used  for
irrigation,  previously subsidized water resources  programs often result
in   such   low   water  prices  that  renovated wastewater  cannot  be
competitively marketed [27].
                                  3-37

-------
In western   states,   reclamation/irrigation    projects  are  presently
financed  by  interest-free loans to fanners or irrigation districts  and
can  be  repaid  in  40  years  with the first payment due 10 years from
project  completion  for  a  50  year  total payback  period.   In eastern
states,  up to 50% of the cost of supplying irrigation water  is borne by
the  federal  government;  the  remainder is repaid over 40 years at  low
interest (currently around 5%) L27].
In  cases  where  treated  wastewater  reuse   and  sale  is desired,  the
potential markets for irrigation sales and industrial  cooling or process
water  should  be  evaluated.   If  the  irrigation reuse is not able to
compete  with  existing  federal  programs,   potential   industrial  users
should  be  contacted.   They  may  be  interested  because they are  not
eligible  for  federally subsidized water projects, and may be prevented
from expanding or relocating because of a lack of usable water.


     3.6.3  Land Use
The planner should be cognizant of the full  spectrum of land uses  in  the
study  area.   Further,  he  must  be  aware  of the community  goals  and
objectives  expressed  by  the  proposed distribution of land use  in  the
area's  general  plan.  With this knowledge, the planner can develop  the
opportunities for land treatment sites that  will  help achieve these land
use  goals  and objectives.  Further, the site location, type of system,
and  related  facilities  can  be planned to optimize conformance  to  the
proposed environmental and social setting.


As  a  general   guide,  the  type  of land uses that are encountered  are
residential,  commercial,  industrial, recreational, urban  open  space,
agricultural,  wilderness,  and  greenbelt  preserves.    In urban  areas,
residential,  commercial,  and industrial  uses are the most difficult to
develop  compatible plans for, whereas recreational and urban open space
uses  are the easiest.  Agricultural, wilderness, and greenbelt preserve
uses  are  most  easily  incorporated  into  land treatment site planning
L32J.
A  variety  of  data sources may be used to evaluate present and planned
land  uses for the study area.   Most city,  county,  and regional  planning
agencies  have  land  use  plans  that indicate present land use policy.
Often, the plans for future land use are current,  but actual  land use is
out  of  date.  In this case, satellite earth-imagery photographs may be
helpful.   By  using  LANDSAT  (Land Satellite) or ERTS (Earth Resources
Technology Satellite) photographs, not only present land uses but also a
number  of  very  useful  physical  phenomena,  such as the extent of the
flood   plain,  location  of  unmapped  faults,  and  point  sources  of
pollution,  can  often  be determined [33J.  Although the techniques for
photointerpretation  are a subject beyond the scope of this manual,  true
                                  3-38

-------
color, false color infrared, and color infrared prints of the study area
as  obtained from the USGS, can provide valuable,  up-to-date information
L33J.
When  completed,  the  Land  Use Data and Analysis (LUDA)  Program of the
USGS  will  be  an  invaluable  planning  tool.   LUDA  will   provide  a
comprehensive collection and analysis of land use and land cover data on
a  nationwide  basis.   Individual  land use/cover maps will  be released
following compilation.  Periodic revision of the data is planned.


Once  the  land  uses  have  been  identified,  the study  area should be
divided into population density areas for comparison with  the land uses.
The preferred sites tend to lie in areas that have the lowest population
densities  (5  persons  per  acre  or  less)  L32J.   This will have the
positive side effect of minimizing the number of relocations  (with their
attendant  costs  and legal problems) that may be required.  Those sites
with  the  lowest population density and with compatible land use should
be ranked high in the evaluation process for preliminary screening.
The  zoning  for each candidate site should be checked.   Zoning laws  are
the  means  by which a community maintains local  control  over what kinds
of  land  uses  are  allowed.   They are also the means  by which the  tax
assessment rates are set L34].  If a site appears to be  excellent in  all
other respects but zoning conflicts exist, use permits or waivers may be
obtained through the agency having zoning authority.


In  addition  to minimum population density, the size of land parcels in
the  study  area  will  strongly  affect  the final  site selection.   The
fewest  number  of  land parcels needed to develop a site will result in
the  least  number  of  property acquisitions or lease contracts and  the
relocation  of  the  least  number of families.  Assessors plats are  the
usual source of this type of information.


     3.6.4  Environmental Setting
Most  public  projects  require  an  assessment  of their impacts to the
environment.    Although   the   environmental   impact  statement  (EIS)
procedure  is  lengthy  and  described  in  numerous  sources,   a  brief
description of certain key topics is presented.
          3.6.4.1   Vegetation and Wildlife


The  important  relationships  are  between  the ecological  communities.
Once  these  are  defined as closely as possible, the task of evaluating
                                  3-39

-------
how  the  overall ecosystem may adjust to project-created stress becomes
easier  to accomplish, and the results are easier to relate to decision-
makers L35].
If  the  interrelationships  of  the various plant and animal  ecosystems
cannot  be  defined  sufficiently  to evaluate the stress, the following
information, as a minimum, should be obtained:

     •    The habitats of rare or endangered species [36]

     •    Locations of unique or rare native ecological  communities [36]

     •    Preferred routes of migratory animals or birds

     •    Locations  of  feeding,  watering, nesting, and mating areas—
          especially of  those  animals  that  have  a low tolerance for
          human activity

     t    Areas  whose  ecosystems  would  be  substantially  altered by
          periodically applied water or a raised groundwater table

     •    Plant  communities  with  high  water  tolerance  to  the land
          treatment alternatives
Some  of  the  needed data may be available in the community or regional
land use or comprehensive plans.  Other excellent sources are state fish
and  game  departments  or  the  U.S. Bureau  of  Sports  Fisheries  and
Wildlife.  Colleges  and universities usually have data on the flora and
fauna   of   a   region  in  their  biology  and  zoology   departments.
Conservation  groups,  such  as  the Sierra Club, Audubon Society, Isaac
Walton League, and Ducks  Unlimited, either have access to these data or
know where they can be obtained.  Many communities have a naturalist who
has  intimate  knowledge  of unrecorded data.  If possible, these people
should  be  consulted before and during the definition of the vegetation
and wildlife setting.
In  the  evaluation  of  the sites for the initial and final screenings,
vegetation and wildlife considerations can be significant.  Encroachment
on  the  habitats  of  rare,  endangered,  or  threatened  species could
eliminate  the site from further consideration.  If an entire' study area
has  been  designated as a potential habitat, a field survey is required
for  direct  observations  by  qualified  biologists/zoologists.  In the
absence  of  direct observations, these professionals can usually render
judgments  on  the possibility of the species being found at the various
sites.
                                   3-40

-------
         3.6.4.2  Historical and Archaeological Sites


Because  land  treatment  systems  involve  large   areas  of  land,   the
possibility  of encountering an historical or archaeological site within
the  project  study  area must be carefully considered.  Pursuant to the
National Historic Preservation Act (PL 89-655) of  1966, many states  have
begun  programs  of  indentifying  historic  or archaeologic features or
structures.   Some  states have also developed purchase and preservation
programs  L37].   Reports on the plans are excellent sources of data for
regional  considerations.  Other data can be found in local universities
or college history or geology departments.  Aid should be solicited  from
the   local   historical   or  archaeological  organizations  and  their
individual  members.
     3.6.5  Social and Economic Aspects
The  social  and economic aspects, including relocation, aesthetics,  and
general  public  acceptability,  are  the most difficult for the project
planner/engineer   to  define  and   evaluate.   Gathering  factual   and
statistical  data  about  the study area will be one of the first tasks.
One  excellent  source  is  the  Census   Bureau.   Also,  the  Economic
Development   Administration  may  provide  community  economic  profile
reports.    Regional   and  local  planning  authorities  have  generally
compiled  data  for  land  use,  recreation,  and  employment/population
projections.   The  best  sources,  however, will be the public advisory
group  and  the  feedback obtained at the public participation workshops
and the required public hearings [35, 36, 38, 39, 40].


If  substantial purchase of land is proposed, relocation may be required
of  residences,  farm  buildings,  and  possibly  commercial  buildings.
Relocation  has  both social and economic impacts and the magnitude must
be  fully  assessed.    An  additional  consideration is the proximity of
schools,  churches,  and  cemeteries,  for  which  relocation may not be
socially acceptable L41J.
What  will  be  the  public  reaction  to  land  treatment  and reuse of
renovated  water  alternatives?  Although the recycling of animal  wastes
is  encouraged  and  accepted, . people  are  more  concerned  about  the
application of human wastes to the land.  They generally have misgivings
about  potential  public  health,  odor,  property  values, and nuisance
problems  in  connection  with land treatment, yet these problems  should
not  arise  in  a well-planned, well-engineered, and well-managed  system
L34J.   The aesthetic effects can be enhanced by proper planning and the
use  of  buffer  zones, trees, shrubs, and careful operation to minimize
odor potential, uncontrolled growth of weeds, and standing water.
                                 3-41

-------
The  other  aspect  of  the public acceptability  evaluation—reaction  to
reuse  of  renovated  water—may  depend on  the contemplated  use  of  that
resource.    A   recent   study  conducted  in  10   southern   California
communities  indicates that the public is ready for large-scale reuse  of
renovated  water  for  purposes that do not  involve body  contact  uses  of
renovated water.  In this same study,  government  officials  were surveyed
nationally, and they rated "public acceptability"  lower than  the  general
public  rated  it  in  12  of  the 13  potential reuse  categories.  These
officials  were  generally  the  most  conservative of  the  four groups
surveyed   (general   public,  water  resources  experts,  industry,  and
government officials).  The results are summarized  in  Figure  3-9  [42J.
These  poll  results  should not be considered  indicative of  the  kind  of
acceptance  that may be encountered elsewhere as  Southern California has
had positive experiences with wastewater reclamation.   It was noteworthy
that  local  officials, who deal  with  the public  on  a  daily basis,  rated
public acceptability lower than other  government  officials.   However,  as
reclamation,  conservation of resources,  and water shortages  become more
prevalent,  public  acceptance to wastewater renovation and reuse should
improve.


The  project  planner  or engineer should realize that if land treatment
and  water  renovation  is unknown in  the study area,  it may  represent a
major change in considering wastewater management and  a public education
program may be necessary.  Unless people understand  what is proposed and
how  it  can  benefit  them, any change will be resisted [43J.  A public
advisory  board  can  aid  in  the  acceptance  of  the  land  treatment
alternatives.    The  problem of "representative"  members in the advisory
board  is  not  a  new  one.  A typical  range of  interests for the group
might include the following:

     •    Farmers representing irrigation districts

     •    Property owners in areas that have a  high  potential  for system
          siting

     •    Civic groups interested in community  development

     •    Conservation groups
There  are  essentially  two  types  of  public   participation  programs:
reactive  and  participative.   In reactive  programs,  the  major  events  in
the  planning  process  (e.g.,  alternative sites for consideration) are
presented to the public.   The reactions to  the  information  presented and
the remarks of the participants are incoporated  into  the  final  screening
and selection process [44J.
Participative  planning  differs  in  the  number  of   meetings   and the
alternative  selection process.   A number of  public hearings  are  held in
                                 3-42

-------
                               FIGURE 3-9
      PUBLIC ACCEPTABILITY OF  RENOVATED WATER  REUSE  [42]
                                          LEGEND
100  r-
6ENERAL  PUBLIC ACCEPTANCE
GOVERNMENT OFFICIAL'S  ACCEPTANCE
GOVERNMENT OFFICIAL'S  ESTIMATE OF
    PUBLIC ACCEPTANCE
 BO  -
 40  -
 20  -
                                                       C9     C9    Cfl
                               POTENTIAL REUSE
                                 3-43

-------
which   the   alternatives   are   presented,   and  the  advantages  and
disadvantages   are   listed.    The   next meeting  presents  any  new
alternatives  or  advantages/disadvantages   from  the previous meetings.
Any  rejected alternatives are shown and the reasons for their rejection
are  outlined.  This process is repeated until  a final  selection is made
L38].   The  unique  involvement  of  the  public  at  all  stages of the
alternative  development will generate more useful informed feedback and
public support L44].


The  definition of the social and economic  setting and the  evaluation of
public  acceptance  will  be the result of  working within the study area
framework and constant interaction between  the  participants.


3.7  Evaluation of Alternative Systems
The  number  of  alternatives  to  be evaluated in detail  will depend on
factors specific to each project, and may involve one or more choices of
the  treatment process, the site location, or the recovery/reuse options
for  the  renovated  water.   On the other hand,  the topography and soil
conditions  within  a  given project area may restrict land treatment to
one feasible process, or a very limited number of potential sites may be
available.  A careful preliminary investigation and screening process is
necessary  to  identify  a number of alternatives without sacrificing an
objective approach.


For  the  purposes  of  this manual, the EPA cost-effectiveness analysis
procedures  documented  in  40  CFR 35, Appendix A, are closely followed
[45],   These  procedures must be used in selecting municipal wastewater
management systems submitted for construction grant funding under PL 92-
500.  For  other  planning  situations,  the  EPA  document  provides  a
complete  evaluation  procedure  that  can  be adapted to fit particular
objectives.  General references on engineering economic evaluations [46]
and  benefit/cost  analysis in water resources planning [47] can provide
additional  background  information  for  methods of evaluating alterna-
tives.  The  EPA  procedures  require an evaluation of both monetary and
nonmonetary  factors.   The most cost-effective alternative is described
as follows [45]:

     The  most  cost-effective  alternative shall be the waste treatment
     management  system  determined from the analysis to have the lowest
     present  worth  and/or  equivalent  annual value without overriding
     adverse nonmonetary costs and to realize at least identical minimum
     benefits in terms of applicable Federal, State, and local standards
     for  effluent  quality,  water quality, water reuse and/or land and
     subsurface disposal.


In  the   following  sections, both monetary cost factors and nonmonetary
aspects   of  land  treatment  systems  are   discussed.   Detailed  cost
                                   3-44

-------
evaluation  procedures  are  not  described,  but  methods  of comparing
overall   costs   and   nonmonetary   factors  for  land  treatment  and
conventional systems are discussed.
     3.7.1  Cost Estimating


Factors  that influence both capital  and operation and maintenance costs
are  discussed in the following paragraphs.  Only a few cost figures are
actually  presented, but references are made to specific sources of cost
information.   Because  the  cost  effectiveness  of  land  treatment is
sensitive  to  land cost, a separate discussion for estimating this item
is  included.   Methods  of  evaluating  revenues  and  a  discussion of
tradeoffs  that  are  unique  to  land  treatment cost analysis are also
discussed.
          3.7.1.1  Capital Costs


Curves  for capital costs are available in Costs of Wastewater Treatment
by  Land  Application  [48].   The  Stage  II  curves are recommended in
conducting  cost estimates.  Although the base date for these curves was
February  1973,  they  should not be arbitrarily updated by conventional
cost  indexes.   A  comparison  of  unit  costs  for  key items,  such as
earthwork  and  continuous-move sprinkling equipment, may provide a more
reasonable  estimate  of  the  increase in current local prices over the
prices of February 1973 [49].


Components  that  might  be  used  for  preapplication treatment include
primary  sedimentation  and aerated lagoons.  Their capital costs can be
determined from published cost curves for conventional treatment systems
[50,  51],  recent  construction  bids, and current price quotations, as
necessary.   Additional  cost  estimating  data  have been published for
aerated  lagoons because they are commonly used in conjunction with land
treatment  systems  [48,  52].   Costs should include sludge handling as
well as liquid processing components.


A  checklist  of the items requiring a capital cost estimate is provided
in Table 3-13.  These should be completed for each alternative system.


Salvage  values  at  the  end  of the planning period for structures and
equipment  should  be  based on expected service life.  Appendix A of 40
CFR 35 [45] specifies service lives to be used in Section 201  facilities
planning (under PL 92-500) as follows:

                Land                   Permanent
                Structures             30 to  50 years
                Process equipment      15 to  30 years
                Auxiliary  equipment    10 to  15 years
                                 3-45

-------
                                     TABLE  3-13

                  CHECKLIST  OF CAPITAL COSTS  FOR ALTERNATIVE
                            LAND TREATMENT SYSTEMS [48]
 Alternative No.
 Type of system
                     Average flow 	 mgd
                     Analysis date 	
                                                             Total
                                                            cost, $
                                Amortized
                               cost, S/yra
 Preapplication treatment
 Transmission
 Storage
 Field preparation
 Recovery
 Additional costs
 Service and
 interest factor at
 Landb at
    Mgal
                                            SUBTOTAL
 SUBTOTAL

	 /acre

   TOTAL
 a.  Check  salvage  values, Table 3-14 and preceding text.

 b.  Section 3.7.1.3.
Additional   guidelines  for service life of  irrigation  system components
are  given  in Table 3-14.
                                       3-46

-------
                      TABLE  3-14
SUGGESTED  SERVICE LIFE  FOR  COMPONENTS  OF
          AN  IRRIGATION  SYSTEM |_53Ja
                                            Service  life
                                            Hours   Years
    Well  can casing                          	    20
    Pump  plant housing               •        	    20
    Pump,  turbine
      Bowl  (about 50% of cost of pump unit)    16,000     8
      Column, etc.                           32,000    16
    Pump,  centrifugal                        32,000    16
    Power transmission
      Gear head                              30,000    15
      V-belt                                  6,000     3
      Flat belt, rubber and fabric            10,000     5
      Flat belt, leather                     20,000    10
    Power units
      Electric motor                         50,000    25
      Diesel engine                          28,000    14
      Gasoline or distillate
       Air cooled                            8,000     4
       Water cooled                         18,000     9
      Propane engine                         28,000    14
    Open  farm ditches (permanent)             	    20
    Concrete structures                      	    20
    Concrete pipe systems                    	    20
    Wood  flumes                              	     8
    Pipe,  surface, gated                     	    10
    Pipe,  water works class                  	    40
    Pipe,  steel, coated, underground          	    20
    Pipe,  aluminum, sprinkler use             	    15
    Pipe,  steel, coated, surface use only     	    10
    Pipe,  steel galvanized, surface only      	    15
    Pipe,  wood buried                        	    20
    Sprinkler heads                          	     8
    Solid set sprinkler system                	    20
    Center pivot sprinkler system             	   10-14
    Side  roll traveling system                	   15-20
    Traveling gun sprinkler system            	    10
    Traveling gun hose system                 	     4
    Land  grading0                            	   none
    Reservoirs'1                              	   None
    a.   Certain irrigation equipment may have a lesser  life
        when  used in a wastewater  treatment system.
    b.   These hours may be used  for year-round operation.
        The comparable period in years was based on  a
        seasonal use of 2 000 h/yr.
    c.   Some  sources depreciate  land leveling in 7 to 15
        years.  However,  if proper annual maintenance is
        practiced, figure only interest on the leveling
        costs.  Use interest on capital invested in  water
        right purchase.
    d.   Except where silting from watershed above will fill
        reservoir in an estimated period of years.
                           3-47

-------
          3.7.1.2  Annual  Operation and Maintenance Costs


Operation  and  maintenance costs include  labor,  materials  and  supplies,
and  power  costs.  They may be assumed constant  for the planning  period
though  many  of the costs will vary throughout the period,  particularly
those  which  are  flow-dependent,   such as  power costs for aeration  and
pumping,  and  chemical  costs.   If  flows   are   expected   to   increase
substantially   during   the  planning  period,   varying operation   and
maintenance costs should be analyzed on a  year-by-year basis (life-cycle
cost)  or  by  reducing  the total  future  value of "the increasing  annual
costs to an equivalent annuity amount.


Preapplication  treatment  will require operation and maintenance  labor,
materials  including  chemicals,   and  power  costs.  These costs  can be
determined  from  cost  estimating   sources   for   conventional  treatment
processes  [50,  51,  54].   Additional operation  cost data on aerated
lagoons  can  be  obtained  from  other sources   [48].  Operation   and
maintenance costs for the remaining categories can be found in  reference
[48].   A checklist has also been prepared for operation and maintenance
cost estimating purposes and is shown in Table 3-15.


          3.7.1.3  Land Costs


               3.7.1.3.1  Fee-Simple Purchase


The  land  category  includes the cost of  acquiring land for application
sites,  buffer  zones, service roads, storage reservoirs, preapplication
treatment facilities, administrative and laboratory buildings,  and other
miscellaneous facilities.   Easements for transmission pipelines may  also
be included in this category.
Land   for  preapplication  treatment  facilities  and  other  permanent
structures  is  usually  purchased  outright  if it is not already under
control  of  the  wastewater  management  agency.   Several   options are
potentially  available  for  acquisition or control of the land used for
the  treatment  process.   These  include  outright purchase (fee-simple
acquisition),  long-term  lease or easement, and purchase with leaseback
of the land with no direct involvement in the management of the land.  A
separate  option of simply negotiating contracts with private landowners
to  sell  or  deliver  wastewater  for  application would eliminate land
acquisition as a capital cost.  According to a recent survey, fee-simple
land  acquisition  is preferred by most states, communities, and federal
agencies [55].
Purchase  of  the  land  provides the highest degree of control over the
application  sites  and ensures uninterrupted land availability for both
                                  3-48

-------
                                 TABLE 3-15

           CHECKLIST OF ANNUAL  OPERATION AND MAINTENANCE COSTS
               FOR  ALTERNATIVE  LAND TREATMENT SYSTEMS  [48]
Alternative No.
Type of system
            Average  flow
            Analysis date
Mgal/d
                                                          Annual  cost, $
                                                  Labor   Power   Material    Total
Preapplication treatment
Transmission
Storage
Distribution
Recovery
Additional costs
Mgal
Revenues
L&nd lease
                                        SUBTOTAL
                                           TOTAL
a.  Section 3.7.1.4.
short-term and long-term planning.  In many cases, purchase will  be more
economical than  leasing or easements.  For this option,  land acquisition
is treated as a  simple capital  expenditure.


For projects eligible for PL  92-500 construction grant funding,  purchase
of  land  to  be   used  as  an  integral  part of the  treatment process is
                                     3-49

-------
eligible.   Purchase and leaseback of land for agricultural  or other use
involving  application  of  wastewater  would require an initial  capital
expenditure  and  annual  revenues,  or  negative  operation  costs,  as
discussed in a later section.
Assuming  that  land is purchased,  the capital  cost is determined simply
by  multiplying  the total area required by  the prevailing market value.
Methods  of  estimating  the  total  area required have been discussed  in
Section  3.3.   Because  the final  alternatives usually include specific
sites,  the  prevailing  market  value can  be  estimated from information
supplied by a local source, such as  the tax  assessor's office.   In a few
cases,  the  wastewater management  agency may  already  control  sufficient
land and acquisition is therefore eliminated as a capital  cost factor.


The  costs of relocating residences  and other  buildings must be included
in  the  estimate  of  initial   costs  and   are  highly dependent on the
location.   Agencies  such  as   the   U.S. Army Corps  of Engineers, U.S.
Bureau  of  Reclamation, and state  highway  departments can assist in the
estimates.   For  federally funded  projects, the acquisition of land and
relocation of residents must be conducted in accordance with the Uniform
Relocation Assistance and Land  Acquisition Policies Act of 1970.  In one
case,  relocation  costs  for  moving approximately 200 familes averaged
about  $5000   per family, plus about $300 000  for administration of the
program [42].


EPA  guidelines  require that the salvage value of land be assumed equal
to  the  initial  purchase  price.   Land values may,  in fact,  appreciate
considerably  during  the  planning   period,  particularly if relatively
undeveloped land is purchased initially.


               3.7.1.3.2  Leasing


The  cost  of  leasing  land  for application  purposes is included as  an
operation cost for those alternatives in which  fee-simple acquisition  is
not  a  viable  or  an  economic option. However, long-term leases are
eligible  for  PL  92-500  construction  grant  financing,  if they can  be
shown to be more cost-effective.
It has been estimated that leasing/easements will  be  cost-effective  only
for  several  hundred projects nationwide.  Most  of these  projects would
be  in  arid  or semiarid areas where effluent  has a  high  value  and  land
has  a  low  value.    In  these areas,  some landowners  may be  willing  to
either pay for wastewater effluents,  accept wastewater  effluents free  of
charge,  or  make  leasing  arrangements   at  a  nominal   charge.  To  be
eligible  for  grant  funding,  the lease  or easement should include the
conditions shown in  Table 3-16.
                                 3-50

-------
                                  TABLE 3-16

      REQUIREMENTS FOR LAND LEASING  FOR PL 92-500 GRANT FUNDING  [56]
      •  Limit the purpose of the lease or easement to land application and activities
         incident to land application.

      •  Describe explicitly the property use desired.

      •  Waive the landowner's right to restoration of the property at the termination
         of the lease/easement.

      •  Recognizing the serious risk of premature lease termination, provide for full
         recovery of damages by the grantee in such an event with recovery of the paid
         federal share or, alternatively, retention of the federal share to be used
         solely for the eligible costs of the expansion or modification of the treatment
         works associated with the project. The damages would include the difference
         between the total present worth of treatment works changes resulting from
         premature termination and the costs resulting from expiration of the lease.
         The damages would also include any additional  losses or costs due to unplanned
         disruption of wastewater treatment.

      •  Provide for payment of the lease/easement in a lump sum for the full value of
         the entire term.

      •  Provide for leases/easements for a minimum of twenty (20) years, or the useful
         life of the treatment plant, whichever is longer, with an option of renewal for
         an additional term, as  deemed appropriate.
           3.7.1.4  Revenues


Revenues  can   accrue   from crop  sales, sale  of renovated water,  sale of
treated  effluent  for   land application, or  leaseback of purchased land
for   farming   or  other  purposes.    In the evaluation and comparison of
alternatives,   revenue  estimates  can be viewed as offsetting or  negative
annual   costs,   but  with  a  higher  degree   of  uncertainty  than with
estimating capital  and  operating  costs.  Crop returns  may be anticipated
from   slow  rate  processes  in   which  the wastewater management agency
controls the land and manages the farming, while overland flow and rapid
infiltration   processes  generally   will  not  produce  significant crop
revenues.   In   either   case,  revenues can be expected to offset only a
portion of the  total operating cost.  Prevailing market values for crops
can   usually   be  obtained  from   state university cooperative extension
services,  but   yield estimates must be made  for the proposed conditions
of  application.    These  estimates   are preliminary and can be  based on
typical    yields  for   the  local    area.   In  a  few  cases,   however,
optimization    of  proposed  application  rates  based  on  crop   yield,
revenues,  and   costs   may  be  investigated   during   the development of
alternatives.    Economic models for  such a procedure have been published
[57,  58].
Relatively  little  information   on  crop   revenues   is  available  from
agencies  that   actually   manage  their own  farming operations.   The most
                                      3-51

-------
widely  reported  operation  is  the   one  at Muskegon,  Michigan  {Section
7.6).   During  1975,  the  first  full  year   of  operation,  total  crop
revenues  amounted  to  about  44% of  the  total   operating  expenses,
including  a  farming  management  contract  fee    [59].    The  revenues
increased  an  estimated  60% in 1976.   The farm  operated by San Angelo,
Texas,  where slow rate application of wastewater is used (Section 7.5),
is also reported to be profitable.


For  alternatives that propose purchase  of land by  the  wastewater agency
and  subsequent leaseback to farmers  with  an agreement  to use  wastewater
for  application,  a  second  source   of  income, is the  estimated lease
payment.   In  Bakersfield,  California, this  type  of arrangement brings
revenues  to  the  city  that  are approximately 2Q% of  total treatment
operating expenses [60].
Another major source of income may be the renovated water recovered from
land  treatment  systems, particularly runoff  from overland flow systems
or  pumped  withdrawal  following  rapid infiltration systems.   Possible
markets  for  the renovated water must be investigated on a case-by-case
basis.   Methods of assessing the relative value of renovated wastewater
for  various  uses  and  levels  of  effluent   quality  are discussed in
reference L61J.  Potential  reuse categories and possible user costs that
would  have to be borne as a result of using renovated wastewater rather
than normal supplies are discussed in a separate study [62J.


For  some projects, the quality and quantity of renovated water from all
alternatives   may   not   be   sufficiently  different  to  affect  the
marketability  of the effluent.  For those situations, revenues from the
sale  of  renovated  water may not be a meaningful evaluative factor for
comparison purposes.


               3.7.1.5  Cost Tradeoffs
There are many considerations that can improve the cost-effectiveness of
an  alternative without changing overall  treatment performance.   Some of
the  more important tradeoffs that should be considered in analyzing the
alternatives are summarized in Table 3-17.
     3.7.2  Nonmonetary Considerations


To  complete  the cost-effective analysis as previously defined, a range
of  nonmonetary  factors should be evaluated for each alternative.  This
evaluation also serves as a basis for unavoidable adverse impacts of the
selected  plan  and for outlining mitigation measures for these impacts.
Nonmonetary  factors,  as listed in Table 3-18, may be divided into four
categories:   (1) treatment performance and reliability, (2) environmen-
tal  impacts, (3) resource commitments, and (4) implementation and legal
constraints.
                                  3-52

-------
                                TABLE  3-17
                COST  TRADEOFF CONSIDERATIONS  FOR
                        LAND  TREATMENT  SYSTEMS3
          Option A                     versus               Option B
•  Land  leveling for surface flooding             Sprinkler systems
•  Cash  crop revenues and operating  costs         Forage and cover (requires  less land)
•  High  drawdown rates  from storage               Low dradown rates requiring smaller
   requiring high volume pumps                   pumps and distribution facilities
   (minimizes storage volume)                    (requires more  land)
•  Existing vegetation                           Land preparation for high-nitrogen
                                               uptake vegetation
•  Double cropping                              Perennial crops
•  One 8 hour daily shift, no weekend             Round-the-clock and weekend operation
   application (requires larger                  (higher operating cost)
   pumps, pipes)
•  Automatic systems (high capital)               Nonautomatic  systems (high  operation
                                               and maintenance)

a.   The  list is intended to show some of the more  obvious options.  Many other
   .possibilities will  arise in the  alternative development process.

                                TABLE  3-18

                       NONMONETARY  FACTORS FOR
                     EVALUATION OF  ALTERNATIVES
             1.   Treatment performance and reliability
                 •  Ability to meet effluent quality/water quality goals
                 •  Process reliability and control
                 •  Process flexibility
             2.   Environmental impacts
                 •  Archaeological, historical,  geological sites
                 •  Plant and animal communities
                 •  Surface and groundwaters
                 •  Soils
                 •  Air quality and odors
                 •  Noise and traffic
                 •  Public health
                 •  Land use
                 •  Social issues
                 •  Economic issues
                 •  Secondary (induced-growth)  effects
             3.   Resource commitments
                 •  Land
                 •  Energy
                 •  Chemicals
             4.   Implementation and legal constraints
                 •  Implementation authority
                 •  Water rights
                 •  Existing regulations and plans
                                     3-53

-------
Table 3-18   can  serve  as  a  comprehensive   guideline  for  comparing
alternatives,  but it must be recognized that  each  planning situation is
unique.   Some factors may be relatively insignificant in one situation,
while  others may be critical.  The approach used to compare each factor
for  various alternatives may be selected by the  planner/engineer or may
be  dictated  by  requirements  of  the  study.    For example,  the Urban
Studies Program specifically discourages the use  of numerical  ratings in
the  Impact Assessment and Evaluation Appendix of its reports [35J.   The
planner/engineer must be aware of particular requirements for evaluating
environmental or other factors for a specific  type  of project.


          3.7.2.1   Treatment Performance and Reliability
Alternatives that are not capable of meeting minimum effluent quality or
water  quality  criteria,  and  those  that provide significantly higher
quality but at unacceptable cost, will  normally  be eliminated during  the
preliminary screening process.  Thus, the expected effluent Quality  from
all  alternatives  may be relatively similar and may not provide a basis
for comparison.  However, there are some differences in effluent quality
from  the various land treatment processes, as pointed out in Chapter 2.
These  differences  should  be  noted when two or more processes of  land
treatment  are  being  compared.   There  may also  be  differences   in
performance  when  conventional  and  land  treatment  alternatives   are
compared.   For  example, a comparison of expected effluent quality  from
two  conventional  systems,  three  land  treatment  systems,  and  four
advanced wastewater treatment systems is presented in Table 3-19.


Well  planned  and  operated  land  treatment systems are reliable [64].
Factors  that  affect  the reliability of land treatment systems include
climatic conditions,  natural disasters,  and equipment breakdown.  Future
resource  availability  should  also  be  evaluated,  particularly when
comparing  land  treatment  systems  with  systems that consume a higher
quantity of power and/or chemicals.


The  flexibility  of  any  treatment  system, and all its components, to
adapt to changing conditions should be evaluated.   Conditions that might
change  include  effluent quality standards, wastewater characteristics,
growth  rate or growth beyond the planning period, surrounding land  use,
and  technological  advances.   Of  particular concern in land treatment
systems  is  the future availability of land. Prudent design will avoid
situations on which no land is available for future expansion.
          3.7.2.2  Environmental  Impacts


Information  on  characterizing  various  aspects  of  the environmental
setting was presented in Section  3.6.   With this  background,  the primary
and secondary impacts of each of  the alternative  plans may be assessed.
                                 3-54

-------
                               TABLE  3-19

                   COMPARISON OF  EFFLUENT QUALITY FOR
                    CONVENTIONAL,  LAND TREATMENT, AND
               ADVANCED WASTEWATER TREATMENT SYSTEMS  [63]
                                     Effluent constituent, mg/L
                    System         BOD SS NHa-N  NOa-N  Total N   P


             Conventional treatment

               Aerated lagoon       35  40 10    20     30    8
               Activated sludge     20  25 20    10     30    8

             Land treatment

               Slow rate            1   1  0.5   2.5     3    0.1
               Overland flow         5   5  0.5   2.5     3    5
               Rapid infiltration     5   1 	  10     10    2
Advanced wastewater
treatment3
1
2
3
4

12
15
5
5

15
16
5
5

1
....
26"
	

29
....
io"
—

30
3
30
3

8
8
0.5
0.5
             a. The advanced wastewater treatment systems are as follows:

                1 = biological  nitrification
                2 = biological  nitrification-denitrification
                3 * tertiary, two-stage lime coagulation,
                    and fil-tration
                4 « tertiary, two-stage lime coagulation, filtration,
                    and selective ion exchange
           3.7.2.3  Resource Commitments


The use and conservation of resources—land, energy,  and chemicals—will
be indirectly included in  the  cost analysis, but  the  noneconomic impacts
should be  evaluated as well.   The amount of land  committed to wastewater
treatment   and renovation  will  be larger for land treatment systems  than
for  conventional  treatment   systems.   The  extent   to which this  is  a
negative   or  positive   impact  involves  evaluation   of several factors
discussed   in  the  preceding   section,  including project land use,  and
social  and  economic issues.   It must be recognized  that the use  of the
land   is  necessarily a long-term commitment.  However, the land used for
an  application  site  is   not  destroyed   or irrevocably altered.   When
operations cease, it again becomes available for  other land uses.


                       should   be  compared   independently  of   the  cost
Energy  requirements  should   be   compared  independently  or  tne  cost
analysis.    Land treatment energy  requirements will  depend significantly
on  the   distance and elevation  required for transmission, as well as  on
other   pumping   requirements.    Conventional  or   advanced  wastewater
                                     3-55

-------
treatment  processes  may require relatively high energy inputs,  in part
because  of  the  energy  required  for  additional   sludge handling and
disposal.   Relative  comparisons of energy  requirements for a number of
treatment strategies have been published [54,  64J.
Chemical  requirements  should  be  evaluated  primarily on the basis of
future  availability, which will  depend,  in part,  on the location of the
project.   If  disinfection  or  supplemental   fertilization  is needed,
chemicals  may  be  needed  for  a  land   treatment system.  In advanced
wastewater  treatment,  there are many additional  processes that require
chemicals.    Land  treatment  alternatives  involving  cultivation  and
harvesting  of crops can be viewed as conserving nutrients, whereas most
advanced  wastewater  treatment  methods   for nutrient removal  tie up or
release nutrients in a relatively unusable form.


     3.7.3  Plan Selection
The  approach  taken  to  summarize  and  present  the  results  of  the
evaluation  will  depend  on  the specific planning situation.   Monetary
costs  for  each  alternative  should be expressed on the basis of total
present  worth or equivalent annual cost.   Nonmonetary factors  should be
presented  on  a  numerical  scale or expressed in qualitative terms.   To
the  greatest  extent  possible,  the summary should permit comparison of
land  treatment  and  conventional   treatment  systems  on an equivalent
basis.
The  actual  selection  process  may  involve  the wastewater management
agency, the engineer/planner, technical  or nontechnical  advisory groups,
input  from  citizens  or  special  interest groups, and other interested
governmental   bodies.   The  selected  alternative  is  the  most  cost
effective,  reliably  meets  all   water quality goals, and does not have
overriding nonmonetary impacts.


Once  a  plan has been selected tentatively, the final step should be to
address   any   adverse  impacts  associated  with  the  plan  that  are
unavoidable.   Mitigating  measures  should be outlined to ensure at the
planning stage that such impacts can be minimized.
                                  3-56

-------
 3.8  References


 1.  Flach, K.W.  Land Resources.  In:  Recycling Municipal   Sludges   and
     Effluents on Land.  Champaign, University of Illinois.   July  1973.

 2.  Whiting, D.M.  Use of Climatic Data in Estimating Storage  Days   for
     Soil  Treatment Systems.  Environmental  Protection Agency,     Office
     of Research and Development.  EPA-IAG-D5-F694.   1976.

 3.  Metcalf & Eddy, Inc.  Wastewater Engineering.  New York, McGraw-Hill
     Book Co.  1972.

 4.  Pound,  C.E.   and  R.W.   Crites.   Characteristics  of   Municipal
     Effluents.   In:   Proceedings  of the Joint Conference on  Recycling
     Municipal Sludges and Effluents on Land,  Champaign,  University  of
     Illinois,  July 1973.

 5.  Blakeslee, P.A.  Monitoring Considerations for  Municipal Wastewater
     Effluent  and  Sludge  Application to the Land.  In:  Proceedings of
     the Joint Conference on Recycling Municipal  Sludges and Effluents on
     Land, Champaign, University of Illinois,  July  1973.  pp 183-198.

 6.  Davis, J.A., III and J.  Jacknow.  Heavy  Metals  in  Wastewater  in
     Three Urban Areas.  Journal WPCF, 47:2292-2297, September 1975.

 7.  Hodain, R.H.  The Best Way to Remove Heavy Metals Might Turn  Out  to
     Be Activated Sludge.  California Water Pollution Control Association
     Bulletin, 12:54-55.  April  1976.

 8.  Pound, C.E., R.W.  Crites,  and J.V.  Olson.    Long-Term  Effects  of
     the  Rapid  Infiltration of Municipal Wastewater.  (Presented at  the
     8th International Conference of  the  International  Association  on
     water Pollution Research,  Sydney, Australia.  October 1976.)

 9.  Ketchum, B.H.  and R.F.  Vaccaro.   The  Removal  of  Nutrients   and
     Trace Metals by Spray Irrigation and in  a  Sand  Filter Bed.   In:
     Land  as  a  Waste  Management  Alternative.  Loehr, R.C.  (ed.)  Ann
     Arbor, Ann Arbor Science.  1977.  pp 413-434.

10.  Thomas, R.E.  Personal Communication.  January  1977.

11.  Chen, K.Y., C.S.  Young, T.K.  Jan, and M.  Rohatgi.   Trace   Metals
     in  Waste  Water  Effluents.   Jour.  WPCF.   46:2663-2675,   December
     1974.
12.   National   Interim   Primary   Drinking   Water   Regulations.     US
     Environmental Protection Agency.  40 CFR 141.  December 24,  1975.

13.   Sepp, E.   Disposal  of  Domestic  Wastewater  by  Hillside   Sprays.
     Journal   of  the  Environmental  Engineering Division,  Proceedings  of
     the ASCE.  99(2):109-121, April  1973.
                                     3-57

-------
14.  Soil-PIant-Water  Relationship.   Irrigation, Chapter 1.  SCS National
     Engineering  Handbook,  Section  15.  U.S.  Department of  Agriculture,
     Soil  Conservation Service.  March 1964.

15.  Stone,  J.E.   Soil  As  a Treatment Medium.  In:  Land  Application  of
     Wastes  -  An  Educational  Program, Cornell University.  May 1976.

16.  Reed, S.C.   et al.  Wastewater Management by Disposal on  the  Land.
     Corps  of Engineers,   US Army Cold Regions Research and Engineering
     Laboratory.   Hanover,  NH.  May 1972.  183 p.

17.  Blaney, H.F.   and W.D.   Criddle.  Determining  Consumptive  Use  and
     Irrigation    Water Requirements.   US  Department  of  Agriculture,
     Washington,  D.C.   Technical Bulletin No.  1275.  December 1962.

18.  Kilmer, V.J.,   et  al.   Nutrient  Losses  From  Fertilized  Grassed
     Watersheds   in Western North  Carolina.   Journal of Environmental
     Quality,  3,  No.   3, 1974.  pp  214-319.

19.  Klausner, S.D., et al.   Surface Runoff Losses  of  Soluble  Nitrogen
     and  Phosphorus   Under  Two  Systems of Soil Management.  Journal of
     Environmental  Quality,  3, No.  1.  1974.  pp 42-46.

20.  Nicholls, K.H.  and H.R.  MacCrimmon.  Nutrients in  Subsurface  and
     Runoff    Waters    of    the   Holland  Marsh,  Ontario.   Journal  of
     Enviromental  Quality,  3, No.   1, 1974.  pp 31-35.

21.  Timmons,  D.E.,   R.E.    Burwell,  and  R.F.   Holt.   Nitrogen   and
     Phosphorus   Losses in  Surface  Runoff  From  Agricultural  Land as
     Influenced by  Placement of Broadcast  Fertilizer.   Water  Resources
     Research, Vol.  9,  No.   3.  June 1973.  p 658.

22.  Loehr,  R.C.   Agricultural Waste Management—Problems, Processes  and
     Approaches.   New  York,  Academic Press.  1974.


23.  Walker, W.R.   and W.E.   Cox.   Wastewater  Irrigation:   Its  Legal
     Impact.   Water Sprectrum.  6(2):15-22, 1974.

24.  Large,  D.W.    Legal   Constraints  Imposed  on  Land  Application  of
     Wastewater by  Private  Water Rights Law.

25.  Reid, G.W.,  E.E.   Pritchett, and  S.   Pritchett.   Can  Engineering
     Forecasters   Affect  Water Law?  Journal of the Sanitary Engineering
     Division, Proceedings  of the ASCE.  97(4):479-484, August 1971.

26.  Powell,   G.M.   Design  Seminar  for  Land  Treatment  of  Municipal
     Wastewater Effluents.   EPA Technology Transfer Program.   (Presented
     at  Technology Transfer Seminar.  1975.)  75 p.
                                    3-58

-------
27. National  Water  Commission.   Water  Policies   for   the   Future.
    Washington, D.C.  US Government Printing Office.  June 1973.  579 p.

28. Dewsnup, R.L.  and D.W.  Jensen (eds.).  A Summary-Digest  of  State
    Water  Laws.   National  Water  Commission.   Washington, D.C.  May,
    1973.  826 p.

29. duff, C.B., K.J.  DeCood, and W.G.   Matlock.   Technical  Economic
    and  Legal  Aspects  Involved in the Exchange of Sewage Effluent for
    Irrigation Water for Municipal Use:  Case Study -  City  of  Tucson.
    University  of Arizona, Office of Water Resources Research.  Tucson.
    Project A-022-ARIZ.  December 1972.  74 p.

30. Hutchins, W.A.  Irrigation Water Rights in  California.   University
    of  California,  Division of Agricultural Sciences.      Sacramento,
    Circular 452 (Rev.), February 1967.  55 p.

31. 92 USC, Public Law  92-500,  An  Act  to  Amend  the  Federal   Water
    Pollution Control Act, 86 Stat.  816 (October 18, 1972) 89 p.

32. Markland, R.E., L.D.   Smith,  and  J.D.   Becker.   A  Benefit-Cost
    Analysis  of  Alternative  Land  Disposal  Waste Water Methods in an
    Urban Environment.  University of Missouri at St.  Louis, School   of
    Business  Administration.   Washington,  D.C.  USDI 14-31-0001-4221.
    US Department of the Interior, Office of Water  Resources  Research.
    January 1, 1974.  234 p.

33. Godfrey,  K.A.   (ed.).    Satellites   Help   Solve   Down-to-Earth
    Engineering Problems.  Civil Engineering.  45:49-53, August 1975.

34. Morris, C.E.  Societal and Legal Constraints.  In:  Land Appl ication
    of Wastes - An Educational Program, Cornell University.  May 1976.


35. Department of Defense, Department of the Army, Corps  of  Engineers,
    Urban  Studies Program, Federal Register, 39 No.  130 part III (July
    5, 1974) 19 p.

'36. State of California Water  Resources  Control  Board.  Environmental
    Impact  Report and  Public  Participation  Guidelines for Wastewater
    Agencies, Sacramento CA.  State of California.  July 1973.  17 p.

37. McHarg, I.L.  Design with Nature.  Garden City, Doubleday & Company,
    Inc., 1971.  197 p.

38. Sargent, H.L., Jr.  Fishbowl  Planning  Immerses  Pacific  Northwest
    Citizens in Corps Projects.  Civil  Engineering.  42:54-56, September
    1972.

39. Guidance for Preparing a Facility Plan.     Environmental Protection
    Agency, Municipal  Wastewater  Treatment  Works  Construction  Grants
    Program.  (Revised) May 1975.
                                   3-59

-------
40.  Guidelines for Areawide Waste   Treatment  Management  Planning.
     Environmental   Protection  Agency.   Washington,  D.C.  August 1975.
     145 p.

41.  Postlewait,  J.C.   Some Experiences  in Land Acquisition  for  a  Land
     Disposal   System  for Sewage Effluent.   In:  Proceedings of the Joint
     Conference on  Recycling Municiple Sludges  and  Effluents  on  Land,
     Champaign, University of Illinois,  July 1973.  pp 25-38.

42.  Stone,  R.   Water  Reclamation:   Technology  and  Public  Acceptance.
     Journal   of  the   Environmental Engineering Division, Proceedings of
     the ASCE.   102(EE3):581-594, June 1976.

43.  Dunbar,  J.O.   Educational  and Informational  Needs  for  Achieving
     Public    Acceptance.     In:    Land  Application   of   Wastewater.
     Proceedings  of  a Research Symposium Sponsored by the USEPA, Region
     III,  Newark,  Del a.   November  1974.  pp 35-38.

44.  Warner,  K.P.   A State of the Art  Study  of  Public  Participation  in
     the  Water  Resources  Planning  Process.   University  of Michigan,
     School  of Natural  Resources,   Environmental   Simulation  Laboratory.
     Washington,  D.C.   NWC-SBS-71-013.  National  Water Commission.  July
     1971.  233 p.

45.  US  Code  of  Federal  Regulations,   40  CFR 35, Appendix A, Cost-
      Effectiveness Analysis.

46.  Grant,  E.L.  and W.G.  Ireson. Principles of Engineering  Economy.
     New York,  Ronald Press.  1970.

47.  James,  L.O.  and R.R.  Lee. Economics  of Water Resources  Planning.
     New York,  McGraw-Hill Book Company, 1971.  615 p.

48.  Pound,  C.E., R.W.   Crites, and D.A.  Griffes.  Costs  of  Wastewater
     Treatment  By  Land  Application.   Environmental Protection Agency,
     Office  of Water Program Operations.  EPA-430/9-75-003.  June 1975.

49.  Crites,  R.W.  Use of Land Application Cost Curves.   In:  Proceedings
     of  the   Sprinkler   Irrigation    Association,   Annual   Technical
     Conference,  Technology  for a Changing World, Kansas City. February
     22-24,  1976.  pp 126-130.

50.  VanNote, R.H., et al.  A Guide to the   Selection  of  Cost-Effective
     Wastewater  Treatment  Systems.    Environmental Protection Agency,
     Office of Water Program Operations.  EPA-430/9-7-002.  July 1975.

51.  Patterson, W.L.  and R.F.  Banker.  Estimating  Costs  and  Manpower
     Requirements  for Conventional Wastewater Treatment  Facilities.   EPA
     17090 DAN.  October 1971.

52.  Sanks,   R.L.,  T.     Asano,   and  A.H.     Ferguson.    Engineering
     Investigations for Land Treatment and Disposal.   In:  Land Treatment
     and  Disposal   of  Municipal   and Industrial  Wastewater. Sanks, R.L.
     and T.   Asano (eds.). Ann  Arbor,  Ann  Arbor Science.   1976.   pp
     213-250.

                                   3-60

-------
 53.  Evaluation of Land Application Systems.    Office  of  Water  Program
     Operations,   Environmental   Protection   Agency.   EPA-430/9-75-001.
     March 1975.

 54.  Battelle-Pacific Northwest Laboratories.    Evaluation  of  Municipal
     Sewage   Treatment   Alternatives.     (Prepared   for   Council    of
     Environmental Quality.  February 1974.)

 55.  Don Sowle Associates, Inc.  An Assessment of the Impact of Long-Term
     Leases and Easements on  the  Construction  Grants  Program.    Final
     Report to the Environmental  Protection Agency.   Arlington, Va.   July
     ly?6.

 56.  Environmental Protection Agency.  Grant  Eligibility of Land Acquisi-
     tion for Use in Land Treatment and Ultimate  Disposal  of  Residues.
     Program Requirements Memorandum No.   77-5.  December 15,  1976.

 57.  Christensen, L.A., L.J.   Conner,  and  L.W.   Liddy.   An Economic
     Analysis  of  the  Utilization  of  Municipal   Waste  Water for Crop
     Production.  Department of Agricultural   Economics,  Michigan  State
     University,  East  Lansing.    Report  No.   292.   US  Department  of
     Agriculture, Economic Research Service,  Natural   Resource  Economics
     Division.  November 1975.  40 p.

 58.  Seitz, W.D.  and E.R.  Swanson.  Economic Aspects of the Application
     of Municipal Wastes to Agricultural  Land.  In:   Proceedings  of the
     Joint  Conference  on  Recycling  Municipal  Sludges and Effluents  on
     Land, Champaign, University  of Illinois,   July  1973.  pp 175-182.

 59.  Walker,  J.M.   Wastewater:   Is  Muskegon  County's  Solution   Your
     Solution?    U.S.   Environmental  Protection  Agency, Region V, Office
     of Research and Development.  September  1976.

 60.  Crites, R.W.  Wastewater Irrigation:  This City Can  Show  You   How.
     Water and Wastes Engineering.  12:49-5U,  July  1975.

 61.  Schmidt, C.J.  and E.V.  Clements,  III.   Demonstrated Technology and
     Research Needs for Reuse of  Municipal  Wastewater.      Environmental
     Protection Agency.  EPA-670/2-75-038.   May 1975.

 62.  Banks,  H.O.   et  al.   Economic  and  Institutional  Analysis   of
     Wastewater  Reclamation  and Re-Use Projects.   Leeds, Hill &  Jewett,
     Inc.  Washington,  D.C.  OWRR C-1912.  US Department of the Interior,
     Office of Water Resources Research.   December  1971.  171 p.

 63.  Pound,  C.E.,  R.W.   Crites,  and  R.G.     Smith.    Cost-Effective
     Comparison  of  Land  Application and Advanced Wastewater Treatment.
     Environmental   Protection   Agency,    Office   of   Water   Program
     Operations.  EPA-430/9-75-016.  November 1975.

64.  Metcalf & Eddy, Inc.  Report to National  Commission on Water  Quality
     on Assessment of Technologies and Costs  for Publicly Owned Treatment
     Works.  September 1976.
                                   3-61

-------
                                  CHAPTER 4

                            FIELD INVESTIGATIONS
4.1   Introduction
The  primary  information   for a specific  site can usually be  found in a
USDA-SCS   county  soil   survey.  Detailed  field investigations are often
needed, however, to assess  the suitability of  a site for land  treatment.
The  intent of this chapter is to outline  those tests normally conducted
for  each  type of land treatment process,  the  reasons for their use,  and
the  conclusions  that   can be reached from  the results.  The  procedures
for  conducting  these   tests  are  discussed   elsewhere:  infiltration,
permeability,   and  aquifer  tests  are  discussed  in   Appendix  C;  and
physical   and   chemical  soil   tests  are  discussed in Appendix F.  The
significance  of various wastewater characteristics to land  treatment is
also presented.  The field  tests normally  associated with land treatment
processes  are  summarized in Table 4-1.
                                  TABLE 4-1

            SUMMARY OF FIELD TESTS FOR LAND TREATMENT PROCESSES
Properties
Wastewater
constituents
Soil physical
properties
Soil hydraulic
properties

-
Slow rate (SR)
Nitrogen, phosphorus,
SARa, ECa, boron
Depth of profile
Texture and structure
Infiltration rate
Subsurface
permeability
Aquifer tests
(optional )
Processes
Rapid
infiltration (RI)
BOD, SS, nitrogen,
phosphorus
Depth of profile
Texture and structure
Infiltration rate
Subsurface
permeability
Aquifer tests

Overland
flow (OF)
BOD, SS, nitrogen,
phosphorus
Depth of profile
Texture and structure
Infiltration rate

     Soil chemical
     properties
pH, CEC, exchange-
cations (% of CEC),
ECa, metalsb,
phosphorus adsorp-
tion (optional)
pH, CEC, phosphorus
adsorption
pH, CEC, exchange-
able cations (* of CEC)
    a.  May be applicable to arid and semiarid areas.
    b.  Background levels of metals such as cadmium, copper, or zinc in the
        soil should be determined if food chain crops are planned.
                                     4-1

-------
4.2  Wastewater Characteristics
The  wastewater  constituents  to  be characterized for the various  land
treatment processes will  vary with the climate  and the discharge  quality
requirements.   For  example,  for  slow rate systems  in humid  areas the
sodium  adsorption  ratio (SAR) and electrical  conductivity (EC)  will  be
less  important  than  they  are  in  arid  areas.   The discharge  quality
requirements for surface water will be provided in the discharge  permit.
The  discharge  quality requirements for groundwater can include  nitrate
nitrogen and trace elements, as presented in Section 5.1.1.
For   constituents   such   as  BOD,   suspended   solids,   nitrogen,   and
phosphorus,  the  concentrations  are used  to  compute the loading  rates.
These rates can be compared to soil  treatment  mechanisms  as  discussed in
Section  5.1.   For  trace  elements,  the   allowable  loadings  are  also
discussed  in  Section 5.1.  For inorganic  constituents of importance to
slow rate systems, guidelines are presented in Table 4-2.
4.3  Soil Physical  and Hydraulic Properties
The  physical   and  hydraulic properties  of  soils are interrelated.   For
example,  a  major  reason for establishing  the  depth of the  profile  and
the texture and .structure is to determine the  hydraulic  capacity.   Depth
of  the  soil   profile  above  bedrock  is"  also  important in  assessing
wastewater  renovation  (slow rate and rapid infiltration processes)  and
in  assessing  practical  limits on earth  moving.  Interpretation  of soil
physical and hydraulic properties is presented in Table  4-3.
4.4  Soil Chemical Properties


Chemical  properties  are  of  importance  in   assessing  (1)   potential
treatment  efficiency  for  infiltration  systems,    (2) need   for  soil
amendments,  and  (3) baseline  levels  of  any constituents expected  to
accumulate in the profile and cause long-term  problems.
Both  chemical  and biological  treatment mechanisms are affected by soil
pH.   Chemical  removal mechanisms for phosphorus change with pH (Appen-
dix B).   Biological  activity  is reduced as  the pH drops below about 5.
The effects on plants are presented in Table  4-4.


The  cation  exchange  capacity  (CEC)  is a  measurable indicator of the
potential adsorption capacity for trace elements.  The percentage of the
CEC occupied by exchangeable sodium (ESP) is  important to maintenance of
soil permeability.
                                   4-2

-------
                             TABLE  4-2

RELATIONSHIP  OF  POTENTIAL PROBLEMS  TO  CONCENTRATIONS  OF
  MAJOR INORGANIC CONSTITUENTS  IN  IRRIGATION  WATERS
             FOR ARID AND SEMIARID CLIMATES  [1]
   Problem and related constituent
No problem
Increasing
 problems
                                                                Severe
Salinity3
  EC of irrigation water, mmhos/cm

Permeability
  EC of irrigation water, mmhos/cm

  SAR (sodium  adsorption ratio)*5

Specific ion toxicityc
  From root absorption

    Sodium (evaluate by SAR)

    Chloride,  meq/L
    Chloride,  mg/L
    Boron, mg/L
  From foliar  absorption (sprinklers)"1

    Sodium, meq/L
    Sodium, mg/L

    Chloride,  meq/L
    Chloride,  mg/L

Miscellaneous6
        meq/L
  HC03, mg/L
   <0.75    0.75-3.0
   >0.5

   <6.0
   <3

   <4
 <142

   <0.5
   <3.0
  <69

   <3.0
 <106
  3.0-9.0

  4.0-10
  142-355

  0.5-2.0
   >3.0
  >69

   >3.0
 >106
             >3.0
   <0.5      <0.2

  6.0-9.0    >9.0
  >9.0


>355

 2.0-10.0
PH
   <1.5       1.5-8.5     >8.5
  <90          90-520   >520

   Normal range =  6.5-8.4
Note:  Interpretations are based on  possible effects of constituents on
       crops  and/or soils.  Suggested  values are flexible  and  should be
       modified  when warranted by local experience or special  conditions
       of crop,  soil, and method of  irrigation.
a.  Assuming  water for crop plus water needed for leaching requirement
    will be applied.  Crops vary in  tolerance to salinity.   Electrical
    conductivity (EC) mmhos/cm x 640 = approximate total dissolved
    solids (TDS) in mg/L or ppm; mmhos x  1,000 = micromhos.
             Na
b.
    where Na  =  sodium; Ca = calcium; Mg = magnesium, in all meg/L.

    Most tree crops and woody ornamentals are sensitive to  sodium and
    chloride  (use values shown).   Most annual crops are not sensitive.

    Leaf areas  wet by sprinklers  (rotating heads) may show  a  leaf burn
    due to sodium or chloride absorption under low-humidity,  high-
    evaporation conditions.  (Evaporation increases ion concentration
    in water  films on leaves between rotations of sprinkler heads.)

    HCO, with overhead sprinkler  irrigation may cause a white carbonate
    deposit to  form on fruit and  leaves.
                                   4-3

-------
                                   TABLE 4-3
         INTERPRETATION OF  SOIL PHYSICAL  AND HYDRAULIC PROPERTIES
           Depth of soil profile, ft
            2-5
             5-10
           Texture and structure
             Fine texture, poor structure
             Fine texture, well-structured
             Coarse texture, well-structured
           Infiltration rate, in./h
              0.2-6
             >2.0
             <0.2
           Subsurface permeability
             Exceeds or equals infiltration rate
             Less than infiltration rate
Suitable for OF0
Suitable for SR and OF
Suitable for all processes

Suitable for OF
Suitable for SR and possibly OF
Suitable for SR and RI

Suitable for SR
Suitable for RI
Suitable for OF

Infiltration rate limiting
May limit application rate
           a. Suitable soil depth must be available for shaping of overland flow
              slopes.  Slow rate process using a grass crop may also be suitable.
           1 ft = 0.305 m
           1 in. = 2.54 cm
For   slow rate  systems that  emphasize agricultural  crop production, soil
tests  will  be conducted for the major  nutrients—nitrogen,  phosphorus,
and   potassium;   boron;  gypsum  content;  and insoluble calcium (CaC03).
While  the  latter  three  are  most  applicable   on   arid climates, the
remainder  are  applicable   to  all  locations.    These  tests  should be
conducted  and  the results interpreted for both crop  production and land
application aspects under the supervision  of a qualified soil scientist.
4.5  Other Field  Investigations
     4.5.1   Soil  Borings
When   field  investigations are  conducted  during the  facilities  planning
stage   for assessing the suitability of the site,  it  may be necessary to
conduct  soil  borings.   Existing  well   logs  can   provide   additional
information   if   the  wells   are  located  within  a  similar  geologic
formation.   Generally  the   shallow (up to 10 ft  [3  m] deep)  soils work
                                      4-4

-------
can be performed  using  a  soil auger (Figure 4-1)  or a  backhoe.   The soil
horizons  exposed  by a backhoe are illustrated  in  Figure  4-2.  For deeper
investigations  of soils  and groundwater,  drill  rigs can be used (Figure
4-3).   The  drill  holes can be  small  diameter with 2 to 4 in.  (5 to  10
cm)  being typical.  The soil removed should be logged  and notations made
for  depths  at   which  groundwater  and  restricting layers to  hydraulic
movement  are encountered.
                                     TABLE 4-4
                     INTERPRETATION OF SOIL  CHEMICAL TESTS
               Test result
             Interpretation
          pH of saturated soil paste
           <4.2
           4.2-5.5
           5.5-8.4
           >8.4

          CEC, meq/100 g
           1-10
           12-20
           >20
          Exchangeable cations,
          % of CEC (desirable  range)
           Sodium
           Calcium
           Potassium
          ESP, % of CEC
           <5
           >10
           >20
          ECe, mmhos/cm at 25"
          of saturation extract
           <2
           2-4
           4-8
           8-16
Too acid for most crops to do well
Suitable for acid-tolerant crops
Suitable for most crops
Too alkaline for most crops, indicates a possible
sodium problem
Sandy soils (limited adsorption)
Silt loam (moderate adsorption)
Clay and organic soils (high adsorption)
60-70
5-10

Satisfactory
Reduced permeability in fine-textured soils
Reduced permeability in coarse-textured soils
No salinity problems
Restricts growth of very salt-sensitive crops
Restricts growth of many crops
Restricts growth of all but salt-tolerant crops
Only a few very salt-tolerant crops make
satisfactory yields
      4.5.2   Groundwater
Knowledge of the  existing  groundwater quality beneath a  site can  provide
information   on   quality   objectives  of  treated  water.   As indicated in
Section  5.1.1   the  determination  of the groundwater case (1,  2, or 3)
                                        4-5

-------
depends  on  the  use and quality of the groundwater.   Wells on adjacent
land  should  have  similar  quality if located within the same aquifer.
Some  soil   borings  can  also  be  used as observation wells for system
monitoring.
                                FIGURE 4-1

              CLOSED AND OPEN BARREL AUGERS AND TILING SPADE
                                             . -Or?'-;
     4.5.3  Vegetation and Topography
Site  inspections  are  necessary  to assess the existing vegetation and
topography.   The  plant  species  growing  in an area can be used as an
indication  of  soil  characteristics  relating  to  plant growth.  They
should not be used as the only means of problem assessment.  However, if
their  occurrence  is  noted,  detailed  soil  investigations  should be
conducted  to  assess the extent of the problem.  Some plant species and
the probable indication of soil characteristics are given in Table 4-5.
The  topography should be mapped prior to final design to allow accurate
earthwork  computations.   Both  the  existing vegetation and topography
should be assessed for costs of clearing and field preparation.
                                   4-6

-------
             FIGURE 4-2




   SOIL  PROFILE  WITH TWO HORIZONS
• •   f
                 4-7

-------
               FIGURE 4-3



TYPICAL DRILL RIG USED FOR SOIL BORINGS
                   4-8

-------
                                    TABLE 4-5
                         PROBABLE SOIL CHARACTERISTICS
                            INDICATED  BY PLANTS [2]a
                   Plant species
             Probably indicates
               Alpine fir
               Spruce
               Cattails
               Sedges
               Willow
               Dogwood
               Needle and  thread grass
               Western wheat grass
               Salt grass
               Mexican fireweed
               Grease wood
               Foxtail
               Ponderosa pine
               Good sage brush
                      high water table
                      high water table
                      high water table
                      high water table
Poorly drained soil, high water table
Poorly drained soil, high water table
Poorly drained soil.
Poorly drained soil:
Poorly drained soil,
Poorly drained soil.
Light textured, sandy soil
Heavy textured, poorly drained soil
Highly saline soil
Highly saline soil
Highly saline soil, sodium problems
Salt, sodium, high water table
Dry soil
Good and  deep soil
               a.   Primarily for western states.  Similar information for
                   other locations can be found in county soil surveys.
4.6   References
 1.   Ayers,   R.S.  and   R.L.
      Water    Quality    for
      Cooperative Extention.
Branson.    Guidelines for Interpretation of
Agriculture.      University   of  California
1975.
 2.   Sanks,    R.L.,    T.    Asano,  and  A.   H.    Ferguson.    Engineering
      Investigations   for   Land   Treatment   and    Disposal.      In:    Land
      Treatment  and   Disposal   of  Municipal   and  Industrial Wastewater.
      Sanks,   R.L.   and  T.   Asano (eds.).   Ann  Arbor, Ann  Arbor  Science.
      1976.   pp 213-250.
                                         4-9

-------
                                CHAPTER 5

                             PROCESS  DESIGN
5.1   Land Treatment Process Design
The  design  of a land treatment process does not lend itself to a  step-
by-step procedure.  The two most important determinations in design are:
(1) selection  of the site and treatment process, and (2) calculation  of
the  required  field  area.   The  iterative  nature of site and process
selection  is described in Chapter 3 and the decisions reached there are
assumed  to  be  inputs  to  this chapter.  In this chapter, the process
design  discussion  centers  on  determining  the critical  loading  rates
required to calculate the field area.


This chapter is organized into discussions of (1) the process design for
slow  rate, rapid infiltration, overland flow, and wetlands application;
(2) system  components  such  as preapplication treatment (5.2), storage
(5.3),  distribution  (5.4), and effluent recovery (5.5); (3) vegetation
selection  and  agricultural  management;   (4)  system  monitoring, and
(5)  facilities design guidance.  The purpose of the chapter is to  focus
on design aspects unique to land treatment.


Much  background  detail  is  provided  to familiarize the environmental
engineer with  land  treatment.  Practices common to most engineers will
not be discussed.  Detailed cost data are not provided,  but sources for
such information are described in Chapter 3.
The process design procedure for land treatment starts with the required
final  effluent  quality.   For  each process, the critical loading  rate
(usually  hydraulic  or  nitrogen) is then determined.  The loadings and
removals  of BOD, SS, phosphorus, trace elements, and microorganisms are
also  discussed  as they may be important in estimating effluent quality
or the expected life of the selected site.  Extensive discussions of the
chemistry  and  microbiology  of  nitrogen,  phosphorus,  pathogens, and
metals are presented in the appendixes.
     5.1.1   Effluent Quality Criteria
As  in  conventional  process design, it is first necessary to determine
the  quality required for the treated effluent produced by the system as
well  as  the  influent  wastewater  quality.   The wastewater quality is
discussed  in Chapters 3 and 4.   The expected  treated water quality  from
slow  rate, rapid infiltration,  and overland flow was presented in Table
2-3.
                                   5-1

-------
Surface  discharge  of  treated water is  expected from overland flow and
wetlands   systems.    Surface   discharge   from   slow  rate  and  rapid
infiltration  systems can result from the installation of underdrains or
wells.   The quality criteria for surface discharges  are established for
the particular watercourse by state and federal agencies.


Subsurface   discharge   consists  of  percolate   from  slow  and  rapid
infiltration  systems.   Because  of  the  clay   soils  associated  with
overland flow and wetland systems, little percolating (usually 5 to 20%)
of  the  applied  wastewater  occurs.  There  is  little concern for this
percolate  quality  because  of the reduction  in  wastewater constituents
after passing through fine textured soils.
The  EPA  criteria for best practicable waste  treatment for alternatives
using  land  application  include  three cases for groundwater discharge
[2].-   In  each  case,  the  constituent  concentration is assumed to  be
measured in the groundwater at the perimeter of the site.
     Case 1 -  The  groundwater  can  potentially  be  used for drinking
               water supply.

               The  chemical  and pesticide  levels in  Table  5-1  should
               not  be  exceeded  in  the groundwater.  If the existing
               concentration  of  an  individual   parameter  exceeds  the
               standards,  there  should  be  no  further increase  in  the
               concentration  of  that  parameter  resulting  from land
               application of wastewater.

     Case 2 -  The groundwater is used for drinking water supply.

               The same criteria as Case 1 apply  and the bacteriological
               quality  criteria  from  Table   5-1 also  apply  in cases
               where the groundwater is used without disinfection.

     Case 3 -  Uses other than drinking water  supply.

               1.   Groundwater  criteria should  be established  by  the
                    Regional  Administrator  based  on  the  present   or
                    potential use of the groundwater.

     The  Regional  Administrator  in  conjunction  with the appropriate
     state  officials  and the grantee shall determine on a site-by-site
     basis the areas in the vicinity of a specific land application site
     where  the  criteria in Case 1, 2, and  3  shall  apply.   Specifically
     determined shall be the monitoring requirements appropriate for  the
     project  site.  This determination shall  be  made with  the objective
     of  protecting  the  groundwater for use  as  a drinking water  supply
     and/or   other   designated  uses  as  appropriate  and  preventing
     irrevocable  damage  to  groundwater.   Requirements  shall include
     provisions for monitoring the effect on the  native groundwater.
                                   5-2

-------
Having  established  the   effluent  quality   requirements   for a  surface
discharge   and  for  the   appropriate   class  of groundwater,  the  process
selection   can  be  made or confirmed.   The next step  is to  determine the
needed loading rates to achieve  the requirements.
                                     TABLE 5-1

                 ERA-PROPOSED REGULATIONS  ON INTERIM PRIMARY
                      DRINKING WATER STANDARDS, 1975 [2]
                           Constituent
                        or characteristic
Value
          Reason
        for standard
                    Physical

                      Turbidity, units
                    Chemical, mg/L

                      Arsenic
                      Barium
                      Cadmium
                      Chromium
                     • Fluoride
                      Lead
                      Mercury
                      Nitrates as N
                      Selenium
                      Silver
        Aesthetic
0.05
1.0
0.01
0.05
.4-2.4c
0.05
0.002
10
0.01
0.05
Health
Health
Health
Health
Health
Health
Health
Health
Health'
Cosmetic
Bacteriological
Total col i form, per 100 mi
Pesticides, mg/L
Endrin
Lindane
Methoxychlor
Toxaphene
2,4-0
2,4,5-TP

1

0.0002
0.004
0.1
0.005
0.1
0.01

Disease

Health
Health
Health
Health
Health
Health
                    a.  The latest revisions to the constituents
                       and concentrations should be used.
                    b.  Five mg/L of suspended solids may be  substituted
                       if it can be demonstrated that it does not
                       interfere with disinfection.
                    c.  Dependent on temperature; higher limits for
                       lower temperatures.
                                       5-3

-------
     5.1.2  Slow Rate Process
The  design procedure for the slow rate process  is  iterative  (see  Figure
5-1).   The  field  area  is first calculated  based on hydraulic loading
rates  and  the  wastewater  flow  to  be  treated.   The  area  is  then
calculated  from  the  nitrogen loading rate which  is  determined using  a
nitrogen  balance.   The  larger  area  is  used  in  design.   Both the
acceptable  hydraulic  and  nitrogen  loadings  depend  in part   on the
vegetation  selected  (see  Section 5.6.1).  The discussion of hydraulic
and nitrogen loading rates is followed by discussions  of removals  of BOD
and suspended solids, phosphorus, trace elements,  and  microorganisms.


          5.1.2.1  Hydraulic Loading Rates
The  hydraulic  loading  will   be  limiting   in   situations   where   slow
permeability  soils  are used, or nitrogen limits are not critical.  The
hydraulic  loading  rates  for  the  design   must  be  within  the   soil
capabilities,  as  estimated  (Figure  3-3)   or   measured (Chapter 4 and
Appendix C).
The  hydraulic  loading  is  based  on  a  water  balance  that includes
precipitation, infiltration rate,  evapotranspiration (or consumptive  use
by  plants),  soil  storage  capabilities,  and   subsoil    permeability.
Generally,   the   total    monthly  application   should  be  distributed
uniformly,  but  considerations must  be made for planting,  harvesting,
drying,  and  other  nonapplication  periods.  The application  rate must
then be balanced as shown in Equation 5-1.


                         Lw +  Pr = ET + Wp  + R               (5-1)

where  LW = wastewater hydraulic loading rate, in./wk  (cm/wk)
       Pr = design precipitation,  in./wk (cm/wk)
       ET = evapotranspiration (or crop consumptive use of water),
            in./wk (cm/wk)
       Wn = percolating water,  in./wk  (cm/wk)
        R = net runoff, in./wk  (cm/wk)
The  relationship  in  Equation 5-1  can  be  used  for a weekly  balance,  as
shown,  or  for  monthly  or  annual   balances.   Design  precipitation  is
calculated  from  a  10  year  return frequency  analysis of wetter-than-
normal conditions  using  all  the  available  data  (Section  3.5.4.1).
Evapotranspiration estimates can be  obtained from extension specialists,
land  grant  universities,  or  irrigation  specialists.  Peak  rates for
selected  crops  that affect maximum hydraulic loadings  are presented  in
Section  5.6.1.   Expected  percolating  water can be estimated  from soil
characteristics  and  verified  with  field investigations (Appendix C).
For  slow  rate  systems,  wastewater  is  assumed  to percolate,  so net
runoff,  R , can be assumed to be negligible.
                                   5-4

-------
                           FIGURE 5-1

                  SLOW  RATE  DESIGN  PROCEDURE
          NASTEVATER
        CHARACTERISTICS
                       EFFLUENT
                     REQUIREMENTS
                    (SECTION 5.1.1)
                                  4
                                 SITE
                            CHARACTERISTICS
                          (SECTIONS  3.2, 3.5
                                AND  4.1)
           HYDRAULIC
         LOADING
       (SECTION 5.1.2.1)
   STORAGE
(SECTION 5.3)
 MONITORING
(SECTION 5.7)
                                 I
   FIELD AREA
(SECTION  5.1.2)
                             REMOVALS OF
                            N,  P,  BOD, ETC.
                            PR E A PPL I CAT I ON
                               TREATMENT
                            (SECTION 5.2)
                                 I
 DISTRIBUTION
 (SECTION  5.4)
                                 I
                              GROUNDWATER
                       NITROGEN
                     LOADING  RATES
                   (SECTION 5.1.2.2)
CROP SELECTION
(SECTION 5.6.1)
                                                         AGRICULTURAL
                                                          MANAGEMENT
                                                       (SECTION 5.6.2)
                                                          UNDERDRA
                                                        (SECTION  5

                                      INS
                                      .5.2) I
                             SURFACE WATER
                                5-5

-------
           5.1.2.2  Nitrogen Loading Rates


Nitrogen management for the slow  rate process is  principally crop  uptake
with  some denitrification.  The annual nitrogen balance  is:
                             Lp =  U  + D + 2.7  WC              "

where Ln = wastewater  nitrogen  loading,  lb/acre-yr (kg/ha-yr)
        U = crop nitrogen uptake,  lb/acre-yr (kg/ha-yr)
        D = denitrification, lb/acre-yr  (kg/ha-yr)
       Wp = percolating water, ft/yr (cm/yr)
       Cp = percolate nitrogen concentration, mg/L


Crop   nitrogen  uptake  values are  presented  in Table 5-2.  .  These   values
are   based  on   typical   yields  under   commercial  fertilization  and may
increase  where  conditions  of  excess  nitrogen prevail.   Crop nitrogen
uptake  values   in  design  depend  on   actual  crop  yields  and  local
agricultural  agents should be contacted.  Double cropping  of field crops
such  as corn  and barley can increase the  total annual nitrogen uptake.
                                    TABLE 5-2

                 TYPICAL  VALUES OF CROP UPTAKE OF NITROGEN3
                                 [3,  4, 5,  6]
                                           Nitrogen uptake,
                           Crop               lb/acre-yr


                     Forage crops
                      Alfalfa6         •         200-480
                      Coastal bermuda grass         350-600
                      Kentucky bluegrass           180-240
                      Bromegrass                 116-200
                      Reed canary grass            300-400
                      Sweet clover               158
                      Tall fescue                135-290
                      Quackgrass                 210-250

                     Field crops

                      Barley                    63
                      Corn                     155-172
                      Cotton                    66-100
                      Milo maize                  81
                      Soybeans'3                  94-128

                     Forest crops
                      Young deciduous             100
                      Young evergreen              60
                      Medium and mature deciduous     30-50
                      Medium and mature evergreen     20-30
                     a.  For choice of suitable crop and uptake
                        value, contact the local agricultural
                        agent.
                     b.  Legumes will also take nitrogen from
                        the atmosphere.

                     1 lb/acre-yr = 1.12 kg/ha-yr
                                       5-6

-------
Denitrification   is  difficult   to determine under field  conditions,  but
losses   generally  range  from   15  to   25%  of   the  applied  nitrogen.
Conditions   favorable   to  increased  denitrification are summarized   in
Table  5-3.     Volatilization  is  known  to occur  (see Appendix A)  but is
difficult to  quantify.

                                   TABLE 5-3

                     FACTORS FAVORING DENITRIFICATION
                                 IN THE SOIL
                           High organic matter
                           Fine textured soils
                           Frequent wetting
                           High groundwater table
                           Neutral to slightly alkaline pH
                           Vegetative cover
                           Warm temperature
The   percolate  nitrogen will  be limited  in concentration  to 10 mg/L  for
design  purposes  if   the  flow  is to  Case 1 or  Case 2  groundwater.   An
alternative  approach  is to conduct a geohydrologic study  (Appendix  C)  to
quantify  groundwater  flow.    If  it can then  be shown  that groundwater
quality  leaving  the  site  meets Case 1 or Case 2 requirements, then a
higher  design  percolate nitrogen concentration  should  be allowed.  The
percolating   water  is determined from the water balance.   It affects  the
allowable  loading  of  nitrogen  considerably,   as  illustrated  in  the
following example for both arid and humid climates.


EXAMPLE 5-1:   ANNUAL  NITROGEN  BALANCE FOR DESIGN  PERCOLATE
                NITROGEN CONCENTRATION OF 10 mg/L


        Conditions
                                                     Humid climate  Arid climate
        1.  Applied nitrogen  concentration, Cn , mg/L                25        25
        2.  Crop nitrogen  uptake,  U , lb/acre-yr                   300       300
        3.  Denitrification,  as % of applied nitrogen                20        20
        4.  Precipitation  minus evapotranspiration,  Pr - ET , ft/yr       1.7       -1.7
        The annual water balance, using Equation 5-1, is:
                                 Lw + Pr = ET + Up
                                 or  Wp = Lw + Pr
                                     Wp = Lw + 1.7  (humid)
                                     Wp = Lw - 1.7  (arid)
        The amount of percolating water, Wp ,  resulting from the applied effluent,  Lw  , has a
        significant effect on the allowable nitrogen loading, Ln .
        The annual nitrogen balance, using Equation 5-2, is:
                      Ln = U + D + 2.7 WpCp                                 (5'2'
                      Ln = 300 + 0.2  Ln + (2.7)(LW  + 1.7)00)  (humid)
                      Ln = 300 + 0.2  Ln + (2.7)(LW  - 1.7)00)  (arid)
                                       5-7

-------
The relationship between the nitrogen loading and the hydraulic loading is:

                    Ln = 2.7 CnLw  (U.S. customary)

                    ln = 0.1 CnLw  (SI units)
where Ln = wastewater nitrogen loading, Ib/acre-yr (kg/ha-yr)
     Cn = applied nitrogen concentration, mg/L
     LW = wastewater hydraulic loading, ft/yr (cm/yr)
Therefore, for this example,

                    Ln = (2.7)(25) Lw

                      = 67.5 Lw

                 or Lw = 0.015 Ln

With two equations and two unknowns, the nitrogen balance can now be solved:
                                                                        (5-3)
                                                                        (5-3a)
          Humid climate
Ln = 300
Ln = 300
                   0.2 Ln

                   0.2 Ln
                                  (2.7)(LW +

                                  (2.7)(0.015 Ln
                   Ln = 300 + 0.2 Ln + 0.405 Ln + 45.9

              0.395 Ln = 345.9

                   Ln = 875 lb/acre-yr
          Arid cl imate
           Ln = 300 + 0.2 L
            n

           Ln = 300

           Ln
                                  (2.7)(LW -

                            0.2 Ln + (2.7)(0.015 Ln -

                   Ln = 300 4 0.2 Ln + 0.405 Ln - 45.9

              0.395 Ln = 254.1

                   Ln = 643 lb/acre-yr
Humid climate
1.
2.
3.
4.
5.
Wastewater nitrogen loading, Ln ,
Wastewater hydraulic loading, Lw
Percolating water, Wp , ft/yr
Denitrification, D , Ib/acre-yr
Percolate nitrogen loading, Pn =
, Ib/acre-yr
, ft/yr


2.7 CpWp , lb/acre-yr
875
13.1
14.8
175
400
Arid climate
643
9.6
7.9
129
213
          1 Ib/acre-yr =1.12 kg/ha
          1 ft/yr = 0.305 m/yr
           5.1.2.3   BOD and  SS Removal
As   indicated  in   Table  2-3,  the  expected  BOD concentration of  treated
water  after  5  ft  (1.5   m)   of   percolation  is  less than 2 mg/L.   At
Hanover,  New Hampshire, percolate  BOD ranged from  0.6 to  2.1 mg/L  after
passage  through  5  ft  (1.5   m).    For  a   primary effluent with  a  BOD
concentration  of   about  100  mg/L  at a loading rate of 5  Ib/acre-d  (5.6
kg/ha'd),   the  average  percolate   concentration was 1.5  mg/L [7].   For
industrial   wastewaters,  BOD   loadings have exceeded 200  ib/acre-d (224
kg/ha-d).    Suspended  solids  removals are expected to be  similar to  BOD
removals although few data  are available for existing systems.
           5.1.2.4   Phosphorus Removal
Phosphorus   retention  is   extremely  effective in  slow rate systems as a
result  of   adsorption and  chemical precipitation.   Phosphorus retention
for   sites   can  be   enhanced  by   use of crops such as grass with  large
                                        5-8

-------
phosphorus uptake.   Grass also minimizes soil  erosion and surface runoff
losses.   Field determination of levels of free iron oxides, calcium, and
aluminum,  and  soil pH will provide information on the type of chemical
reactions  that  will  occur.  Determination of the phosphorus  sorption
capacity  of  the  soils  requires laboratory testing with field samples
from the proposed areas (see Appendix F).


The  estimated  phosphorus   retention from the empirical model (Appendix
B.4.4)  can  be  computed  for the loading and soil sorption properties.
Systems  with  strict  phosphorus  control  for  recovered  water should
include  routine  soil  phosphorus monitoring to verify retention in the
soil and system performance.
          5.1.2.5  Trace Element Removal
An  evaluation of the annual applications of trace metals should be made
on  the  basis  of wastewater applications and an estimate of wastewater
concentrations from field testing or existing data (see Table 3-4).  The
assessment  of  trace  metal  concentrations  is especially important in
cases where industrial sources are  present.  The potential  toxicity to
plants can be assessed by comparing loadings computed to the recommended
application  values  for  sensitive  crops   (Table 5-4).  In cases where
annual total application, or applied concentrations approach levels shown
in Table 5-4, system  management  to maintain soil pH at 6.5 or above by
liming may be needed.


          5.1.2.6  Microorganism Removal


The minimizing of public  health  risks  is  a  basic  goal for any wastewater
treatment   system.  The potential for  public health  risks resulting from
land   application   of  wastewater varies  greatly  depending upon specific
site  details  such as:

      1.  Type  of application

      2.  Public access to the  site

      3.  Preapplication treatment

      4.  Population density and  adjacent  land  use
      5.  Type  of disposition of  vegetative  cover

      6.  Natural occurring  and artificial onsite  buffer zones

      7.  Climate

The   U.S.   Army  Medical  Department   and the  EPA have  conducted  and  are
continuing   to  conduct studies  at  operational  land  application sites to
document    microorganism    removal  and   transport   mechanisms.   These
locations   include  Fort  Devens,   Massachusetts, Deer  Creek, Ohio; Fort
Huachuca,   Arizona;   and  Pleasanton,   California.   In  addition,   the
                                   5-9

-------
development  of  a   mathematical
underway by the U.S.  Army.
       model   describing aerosol  transport is
                                    TABLE 5-4

              SUGGESTED MAXIMUM APPLICATIONS  OF TRACE ELEMENTS
                   TO  SOILS  WITHOUT FURTHER INVESTIGATION3
                      Element
Mass application      Typical
to soil,  Ib/acre  concentration, mg/L"
Aluminum
Arsenic
Beryl i urn
Boron
Cadmium
Chromium
Cobalt
Copper
Fluoride
Iron
Lead
Lithium
Manganese
Molybdenum
Nickel
Selenium
Zinc
4 080
82
82
610
8
82
41
164
820
4 080
4 080

164
8
164
16
1 640
10
0.2
0.2
1.4C
0.02
0.2
0.1
0.4
1.8
10
10
2.5d
0:4
0.02
0.4
0.04
4
                      a.  Values were developed for sensitive crops on
                         soils with low capacities to retain elements in
                         available forms  [8, 9].

                      b.  Based on reaching maximum mass application in
                         20 years at an annual application rate of
                         8 ft/yr.

                      c.  Boron exhibits toxicity to sensitive plants at
                         values of 0.75 to 1.0 mg/L.

                      d.  Lithium toxicity limit is suggested at 2.5 mg/L
                         concentration for all crops, except citrus which
                         uses a 0.075 mg/L limit.  Soil retention is
                         extremely limited.

                      1 Ib/acre = 1.12 kg/ha
                      1 ft =0.305 m
      5.1.3   Rapid  Infiltration
The   design  procedure for  rapid  infiltration is  presented in Figure 5-2.
The   principal   differences  from   slow   rate  systems  are (1)  hydraulic
applications   are   greater,  so   greater  reliability   of  permeability
measurements  is  required;  (2)  nitrogen  removal  mechanisms rely  less on
crop   uptake  and   more  on  nitrification-denitrification;  (3)   solids
applications  are   greater;   and   (4)  systems   can be  adapted  to severe
climates.
                                      5-10

-------
                               FIGURE  5-2

                RAPID INFILTRATION DESIGN PROCEDURE
r ~
             WASTEWATER
          CHARACTERISTICS
           (SECTIONS 3.3
              AND 4.2)
                                    EFFLUENT
                                  REQUIREMENTS
                                (SECTION  5.1.1)
                                    I
                                    SITE
                              CHARACTERISTICS
                             (SECTIONS 3.2, 3.5
                                  AND 4.1)
                              PREAPPLICATION
                                 TREATMENT
                               (SECTION  5.2)
             HYDRAULIC
              LOADINGS
         (SECTION 5.1.3.1)
                                   BOD AND SS
                                    LOADINGS
                                 (SECTION  5.1.3)
     STORAGE
~l
  (SECTION 5.3)
                                    I
                FIELD AREA
             (SECTION  5.1.3)
                                              	—H VEGETATIVE COVER
                                REMOVALS  OF
                              N, P,  BOD,  ETC.
      SYSTEM
    MONITORING
   (SECTION 5.7)
                                    I
               DISTRIBUTION
              (SECTION  5.4)
                                    I
                                 DISCHARGE
                                    T
                                             RECOVERY
                                               T
                                GROUNDWATER
                                          SURFACE WATER
                                   5-11

-------
          5.1.3.1  Hydraulic Loading Rates
Hydraulic  loadings  and  subsequent  liquid  movement  through the soil
depend  on  soil  permeability,  subsurface  geological   conditions, and
constituent  loadings.  Annual hydraulic loading rates can range from 20
to  400 ft/yr (6 to 120 m/yr).  Typical  loading rates are shown in Table
5-5.
                                TABLE 5-5

             TYPICAL HYDRAULIC LOADING RATES FOR RI  SYSTEMS
1
Location .
Flushing Meadows, Arizona
Santee, California
Lake George, New York
Calumet, Michigan
Hemet, California
Hollister, California
Fort Devens , Massachusetts
Westby, Wisconsin
Hydraulic
loading rat
ft/yr
364
265
140
no
108
97
94
36
e,
Soil type
Sand
Gravel
Sand
Sand
Sand
Sandy loam
Sand and gravel
Silt loam
Type of
wastewater
Secondary
Secondary
Secondary
Untreated
Secondary
Primary
Primary
Secondary
          1  ft/yr = 0.305 m/yr
System design for a rapid infiltration process includes the interrelated
factors   of   hydraulic   loading  rate  per  application  cycle,  soil
infiltration  capacity, application and resting cycle, solids applied in
the  wastewater, and subsoil  permeability.   Although site investigations
may   show   that  the  infiltration  rate  is  greater  than  the  soil
permeability, the infiltration rate, under design conditions with solids
applications,  will  usually   decrease  and control  liquid applications.
Figure  3-3  can  be  used  for  an  initial   estimate  of  the  average
infiltration  rate.   For  final   design values, soil  infiltration tests
(described  in Appendix C) should be conducted.  The most limiting layer
in  the soil profile should be evaluated and that permeability should be
used in design.


The operating infiltration rate will vary between two values:  one being
the  initial  rate for clean  soil and clear water, and the other being a
decreased  rate  for wastewater,  with a surface accumulation of organics
and  other  suspended  solids.   The cycle of application and resting is
designed to restore the infiltration rate to nearly its initial value by
the  end of the resting period.  For a specific rapid infiltration site,
a  design  decision  has  to   be  made  that  balances  suspended solids
application, land area requirements, and resting requirements.
                                  5-12

-------
          5.1.3.2   Hydraulic Loading Cycles
The  existing  hydraulic loading and resting  cycles of rapid infiltration
systems,  as   given  in  Table 5-6, demonstrate several  design concepts.
Most  systems   are  intended  to  maximize   infiltration rates, although
Flushing  Meadows, Arizona, and Fort Devens,  Massachusetts, experimented
with the cycle to promote denitrification.
                                 TABLE  5-6

                   TYPICAL HYDRAULIC LOADING CYCLES [11]
Location
Calumet, Michigan
Flushing Meadows, Arizona
Maximum infiltration
Summer
Winter
Fort Devens, Massachusetts
Fort Devens, Massachusetts
Lake George, New York
Summer
Winter-
Tel Aviv, Israel
Vineland, New Jersey
Westby, Wisconsin
Whittier Narrows, California
Loading objective
Maximize infil-
tration rates

Increase ammonium
adsorption capacity
Maximize nitrogen
removal
Maximize nitrogen
removal
Maximize infil-
tration rates
Maximize nitrogen
removal

Maximize infil-
tration rates
• Maximize infil-
tration rates
Maximize
renovation
Maximize infil-
tration rates
Maximize infil-
tration rates
Maximize infil-
tration rates
Application
period
1-2 d

2 d
2 wk .
2 wk
2 d
7 d

9 h
9 h
5-6 d
1-2 d
2 wk
9 h
Resting
period
7-14 d

5 d
10 d
20 d
14 d
14 d

4-5 d
5-10 d
10-12 d
7-10 d
2 wk
15 h
Bed surface
Sand (not cleaned)

Sand (cleaned) and
grass cover3
Sand (cleaned) and
grass cover3
Sand (cleaned) and
grass cover3
Grass (not cleaned)
Grass (not cleaned)

Sand (cleaned)3
Sand (cleaned)3
Sandb
Sand (disked), solids
turned into soilc
Grassed
Pea gravel
 a.  Cleaning usually involved physical removal of surface solids.

 b.  Maintenance of sand cover is unknown.

 c.  Solids are incorporated into surface sand.
For  basin surfaces with grass or  vegetation, the need for maintenance is
less strict than for bare surfaces.   Based on operations at  Fort Devens,
the   grass  should  be  allowed   to   grow  and die without placing  heavy
                                   5-13

-------
mechanical   equipment,  which  compacts the  surface,  on the  infiltration
beds.  Periodic harrowing of the  soil  surface  or mowing of the  grass may
be considered depending on aesthetic  demands.


In  summary, system design-for maximum infiltration rates should include
adequate  drying  time  based  on  local   climate and solids loadings  to
restore  infiltration  rates.  If the soil  surface is maintained bare  of
vegetation,  the  surface  should  be  periodically  raked,  harrowed,  or
disked.   Nitrogen  removal   by  denitrification will require additional
considerations  for  lesser  soil   aeration  and  the effect of lessened
opportunity for solids degradation.
          5.1.3.3  Nitrogen Loading Rates
Because  nitrogen  loading  rates  can exceed crop uptake  by an  order  of
magnitude,  crop  uptake  (if a crop is planted)  is relatively minor and
nitrification,  denitrification,  and ammonium sorption are generally  of
greatest importance.
The  retention  of  ammonium  by  the  cation   exchange  capacity  can  be
excellent.   The  conversion  of ammonium to nitrate occurs rapidly  when
short,  frequent  applications are used to promote aerobic  conditions  in
the  soil.   Longer  application cycles,  which  restrict soil  reaeration,
favor nitrogen loss by denitrification.  Available organic  matter  in the
soil  profile  as  a  result of applied BOD also  increases  the amount  of
denitrification.   The  most  comprehensive work  on  nitrogen has  been
conducted at the Flushing Meadows Project (described in Section 7.8).


At the  Flushing  Meadows Project, at a 365 ft/yr  (111  m/yr) application,
the  sustained  removal  of nitrogen was 30% [12].   For lower application
rates  Lance  found that the nitrogen removal  increased to  over 80%  (see
Figure  5-3).   Although the relationship is strictly valid only for the
sandy  soil  and  secondary  effluent  used at Flushing Meadows, similar
relationships   should   exist   for   other   soils   and   wastewaters.
Infiltration rates in the field can be changed by modifying the depth  of
flooding,  compacting  the  soil  surface,  or  by  applying  wastewater
containing higher BOD and suspended solids [10].


When  nitrification  is  the  objective  of  rapid  infiltration,   short
application  periods  followed  by  relatively  long resting periods are
used.   Rapid  infiltration systems will  produce  a nitrified effluent  at
nitrogen  loadings  up  to  60  lb/acre-d (67.2 kg/ha-d).  Nitrification
below 36°F (2°C) and below pH 4.5 is minimal (Appendix A).
                                  5-14

-------
                               FIGURE 5-3

             EFFECT OF  INFILTRATION RATE ON NITROGEN REMOVAL
              FOR RAPID INFILTRATION, PHOENIX, ARIZONA  [10]
UJ
C9
                     90

                     eo

                     70


                     60


                     50



                     40




                     30





                     20
                     1 0
                           1  in./d = 2.54 cm/d
                                                   I
                      10          20     30    40

                              INFILTRATION RATE, cm/d
                                                   5060
          5.1.3.4  BOD and SS Removal
Removals  of BOD and  suspended  solids depend on  the  soil  type  and  travel
distance  in  the  soil.   Removal  of  BOD is primarily  accomplished by
aerobic  bacteria  that  depend on resting periods to  reaerate the soil.
Loading  rates have some effect on removals but  too  many  other variables
such as temperature,  resting period, and soil type are involved to allow
estimation of removals from loading rates alone.  Selected  loading rates
and concentrations in the treated water are presented  in  Table 5-7.
          5.1.3.5  Phosphorus Removal
The  basic  mechanisms  for  phosphorus  removal  are   similar   to those
described for slow rate systems (Section 5.1.2.4).  The coarser  textured
soils  used  for rapid infiltration may have less retention capacity for
phosphorus.   Soil  capabilities  can be estimated from specific testing
(Appendix F; Section F.3.3.2).
                                 5-15

-------
                               TABLE 5-7

              BOD AND SUSPENDED SOLIDS DATA FOR SELECTED
                  RAPID INFILTRATION SYSTEMS [13-16]
Location
Phoenix,
Arizona
Lake George,
New York
Calumet,
Michigan
Hollister,
California
Fort Devens,
Massachusetts
BOD
Average
loading
rate,
Ib/acre-d9
40
47
71
158
78
Suspended solids
Treated water
concentration,
mg/L
0-1
1.2
lib
8
12
Average
loading
rate,
lb/acre-d
54

43
197
...
Treated water
concentration,
mg/L
0.8

...
...
...
Sampling
depths,
ft
100
10
11
25
64
        a.  Total lb/acre-yr applied divided by the number of days in the operating
           season (365 days for these cases).

        b.  Soluble TOC.

        1  lb/acre-d = 1.12 kg/ha-d
          5.1.3.6  Trace Element Removal
As  indicated in Section 5.1.2.5,  heavy metals  are removed from solution
by  the  adsorptive process and by precipitation  and ion exchange in the
soil.   The concerns  about   heavy metals  in rapid infiltration systems
are:   (1)   the  high rates  of application, and  (2) the potentially low
adsorptive  potential  of  the coarse  soils.  The  heavy metal application
criteria  (Table  5-4),  recommended   to  ensure  protection of sensitive
plants   in  slow  rate  systems,  can be   safely  exceeded  for  rapid
infiltration systems because  sensitive agricultural crops are not grown.
          5.1.3.7  Microorganism  Removal
The  mechanisms  of   microorganism removal  include straining, sedimenta-
tion, predation  and   desiccation   during preapplication treatment; des-
iccation  and  radiation  during  application; and straining, desiccation,
radiation, predation, and hostile  environmental  factors upon application
to   the   land.    Removals  of  fecal   col i forms  for  selected  rapid
infiltration systems  are  presented in Table 5-8.
                                 5-16

-------
                                TABLE 5-8

                   FECAL COLIFORM REMOVAL IN SELECTED
                       RAPID INFILTRATION SYSTEMS
Fecal col i forms, MPN/100 ml
£•„,' 1
Location
Phoenix
Hemet,
Calumet
, Arizona
California
, Michigan
type Effluent applied
Sand 1 000 000
Sand 60 000
Sand — a
Renovated water
0-30
11
1-10
- Sampling
• depth, ft
100
8
10
           a.  Untreated wastewater.

           1 ft = 0.305 m
     5.1.4  Overland Flow
Overland  flow systems use the land surface as the treatment medium over
which a thin sheet of wastewater moves and upon which the biological  and
chemical processes occur.  The design procedure is typically to select a
hydraulic loading based on the required treatment performance for BOD in
the  wastewater.  Nitrogen removals or transformations are then assessed
based  on  comparison  with  existing  systems.  The design procedure is
presented in Figure 5-4.
          5.1.4.1  Hydraulic Loading Rates
Hydraulic  loading rates, when untreated or primary effluent is applied,
can  range  from  2.5  to  8  in./wk  (6.4 to 20 cm/wk) depending on the
climate,  required  treatment  performance,  and  detention  time on the
slope.   Lower  values  of  3  to  4  in./wk (7.5 to 10 cm/wk)  should be
considered  (1)  for  slopes greater than 6%, (2) for terraces  less than
150 ft (45 m), or (3) because of reduced biological activity during very
cold  weather.   Thomas  has  reported excellent results using  untreated
wastewater  at about 4 in./wk (10 cm/wk) on 2 to 4% slopes 120  ft (36 m)
long  [17].   Recently, Thomas has experimented with loadings of 6 and 8
in./wk  (15 and 20 cm/wk) with untreated wastewater and primary effluent
and has indicated continued excellent removals of BOD, suspended solids,
and nitrogen [18].
For  lagoon  or secondary effluent, loadings of 6 to 16 in./wk (15 to 40
cm/wk)  can  be  considered.  Lower values of 7 to 10 in./wk (17.5 to 25
cm/wk)  should  be considered when the factors (1) through (3) described
above,   apply.    Loading   rates   and   design  conditions  for  four
demonstration projects are presented in Table 5-9.
                                   5-17

-------
                     FIGURE  5-4

         OVERLAND FLOW DESIGN PROCEDURE
  WASTENATER
CHARACTERISTICS
 (SECTIONS 3.3
    AND  4.2)
    EFFLUENT
  REQUIREMENTS
(SECTION 5.1.1)
                         SITE
                   CHARACTERISTICS
                  (SECTIONS 3.2. 3.5
                       AND 4.1)
                         I




HYDRAULIC
1 nin 1 UP? .*
LUAUINua *
(SECTION 5.1.4.1)
1
PREAPPLICATION
TREATMENT
(SECTION 5.2)
1


STORAGE
(SECTION 5.3)
FIELD
(SECTION
r


BOD AND SS
fc. i ni n i ucc
^ LIMU 1 iluo
(SECTION 5.1.4)
1

AREA
5.1.4)


                     REMOVALS OF
                    N,  P, BOD, ETC.
                          I
                                                     I
          AGRICULTURAL
           MANAGEMENT
                     DISTRIBUTION
                    (SECTION 5.4)
                        RUNOFF
                      COLLECTION
                     (SECTION  5.5)
                          I
                       DISCHARGE
                          T
                    SURFACE  WATER
                        5-18

-------
                                 TABLE 5-9

        SELECTED HYDRAULIC LOADING RATES FOR OVERLAND FLOW SYSTEMS
                                         Hydraulic
                             Type of        loading   Degree of   Slope
                          effluent applied rates,  in./wk 'slope, %   length, ft
Ada, Oklahoma
Ada, Oklahoma
Pauls Valley, Oklahoma
Utica, Mississippi
Raw comminuted
Trickling filter
Oxidation pond
Oxidation pond
4-8
10-16
10.3
2.5-5
2-4
2-4
2-3
2-8
120
120
150
150
       1  in./wk =2.54 cm/wk
       1  ft = 0.305 m
Loading   rates   and   cycles   for an overland flow system are designed to
maintain  active  microorganism growth on the soil  surface.  The operating
principles    are  similar  to  a  conventional   trickling  filter  with
intermittent  dosing.    The   rate  and  length  of application should be
controlled;   anaerobic   conditions   can  result  from  overstressing the
system.   The resting   period  should  be long enough to allow the soil
surface   layer   to reaerate,  yet short enough to keep the microorganisms
in  an  active   state.    Experience with existing systems indicates that
optimum   cycles  range from 6  to  8 hours on and 16 to 18 hours off, for 5
to  6  d/wk   depending   on the time of year.  Application periods may be
extended  during the  summer months  to allow portions of the system to be
taken out of  service  for crop harvesting.
          5.1.4.2  Nitrogen  Removal
Nitrogen  removal  in overland  flow  systems  is  excellent.   Two important
mechanisms   responsible  for   these  removals   are   biological  nitrifi-
cation/denitrification and  crop   uptake.    The overlying  water film and
organic  matter,  and  the  underlying   saturated  soil  form an aerobic-
anaerobic double   layer    necessary   for    nitrification  followed  by
devitrification.   These  conditions  are similar  to  those found in  rice
fields  or  marshes.   The  treated   runoff  quality for  nitrogen at  Ada,
Oklahoma, is shown in Table 5-10.
          5.1.4.3  BOD and SS Removal
Removals  of  BOD,  both  at  Ada,  Oklahoma   and   at Paris,  Texas,  have
improved  with  system  age.  At Ada, after about  100 days  of operation,
the BOD  concentration  in the runoff stabilized at an average of  8  mg/L
for  the  4  in./wk (10 cm/wk) rate [17].  At  Paris,  Texas  (described in
                                  5-19

-------
Section 7.12), the BOD in the treated runoff improved  from  an  average  of
9 mg/L in 1968 to an average of 3.3 mg/L in 1976.


Suspended  solids  removals  are  generally less than  those for  BOD.   At
Ada,  removals  averaged 95% and concentrations ranged  from 8  to 16 mg/L
for  the  4  in./wk  (10 cm/wk) rate [17].  At Paris,  Texas, 245 mg/L  of
suspended solids is applied and the treated runoff typically contains  25
to 30 mg/L of suspended solids [11].


                              TABLE 5-10

              NITROGEN CONCENTRATIONS  IN  TREATED RUNOFF
      FROM OVERLAND FLOW WHEN USING UNTREATED WASTEWATER [17,  18]
                                 mg/L
                                     Loading rate, in./wk

                       Nitrogen forms      4        8
Total
Organic
Ammonia
Nitrate and nitrite
2.9
1.6
0.8
0.5
3
a
a
a
                     a.  Not measured, but assumed to be
                        similar to 4 in./wk loading rate.

                     •1 in./wk = 2.54 cm/wk
          5.1.4.4  Phosphorus Removal
Of  the three major land treatment processes, overland  flow  systems have
the  most  limited  potential  for phosphorus removal.   Because  there is
very  limited  percolation  of  wastewater in overland  flow  systems,  the
soil-water  contact is limited to the soil surface  area.   The  wastewater
flowing  over  the soil surface does not have extensive contact  with  the
components  of  the  soil that normally fix large amounts  of phosphorus.
In  addition,  the  residence  time on the slope  is usually  less than 24
hours.   However,  some  phosphorus appears to be removed  by the organic
layer  on  the  surface  of overland flow slopes  [19] and  the  grass will
take up 30 to 40 lb/acre-yr (33 to 44 kg/ha-yr).
At Ada, Oklahoma, alum was added to the wastewater  prior  to  application.
For  an  application  rate  of  4  in./wk   (10  cin/wk),   the removals of
phosphorus  are  presented in Table 5-11.   Similar  results were obtained
at Vicksburg, Mississippi [20].
                                   5-20

-------
                               TABLE 5-11

            PHOSPHORUS CONCENTRATIONS IN TREATED RUNOFF FROM
                    OVERLAND FLOW, ADA, OKLAHOMA [17]
                   Sample
Concentration of total  Phosphorus
  phosphorus, mg/L    removal, %
Untreated wastewater
Runoff
No alum
14 mg/L alum
20 mg/L alum
9.8

3.7
1.6
1.5


62
84
85
Carlson  et  al. reported 75% phosphorus removal
in greenhouse  studies  at  0.5 in./d (1.3 cm/d)
Melbourne, Australia, phosphorus removals of 35%
reported (Appendix B).
                 from  secondary effluent
                 applications [21].   At
                 from  raw wastewater are
          5.1.4.5  Trace Element Removal
Trace element removal by overland flow is relatively good.  Hunt and Lee
[19]  report  that  .rates  of  removal are greater than 90% for all, and
greater than 98% for some heavy metals.  It is believed that most of the
heavy metals are removed in the surface organic mat.
          5.1.4.6  Microorganism Removal
The  mechanisms  involved  in  the  removal  of  bacteria by  the  soil  in
overland  flow  systems  are similar to those for removal of  metals.   At
the  pilot  study  at  Ada,  Oklahoma,  the  overall  reduction  for total
coliforms  was  about  95%, while fecal coliform reduction was  about 90%
[17].
     5.1.5  Wetlands Application
The  designed  use  of  wetlands  to  receive   and   satisfactorily  treat
wastewater  effluents  is a  relatively new concept.   At  present,  the  use
of  wetlands  has not been incorporated  into large,  full-scale  treatment
systems; however, the potential treatment capacity has been  confirmed at
many  pilot  systems and research sites.  Hydraulic  loadings and  general
performance criteria are given  in Table  5-12.
                                   5-21

-------
ro
no
                                                                          TABLE 5-12

                                              HYDRAULIC  LOADINGS AND GENERAL PERFORMANCE CRITERIA -
                                                     RESEARCH  AND  DEMONSTRATION WETLAND SYSTEMS
                            Location
System  type
                                            Final concentrations, mg/L

Preapplication   Length of    Application       Suspended   Total      Total
  treatment     application   rate, in./d  BOD     solids   nitrogen  phosphorus
                            New York     Constructed
                            [22]        marsh/pond
               Aerated
               Year-round
1.8
16
43
                            Wisconsin    Constructed marsh  Primary and     Year-round
                            [23]                         secondary

                                        Natural  marsh     Primary and     Year-round
                                                         secondary
                                                       5-18    14-80    	

                                                       5-27    90-154    0.5-2
                            a.   Application varies to give detention times of 5 hours to  10 days.
                            b.   At  point in swamp 2.26 mi  (3  640 m) downstream from outfall.
 2.2


10-12


 1-3 •
California
[24]
New Jersey
[25]
Canadian
Northwest
[26]
Minnesota
[27]
Florida
[28, 29].
Constructed marsh
Natural tidal
marsh
Natural swamp

Constructed
peat bed
Natural cypress
dome
Secondary
Secondary

Lagoon and
raw septage
Secondary
Secondary
Year-round ... .... 	 	 <7 2.8
Year-round 2.0-5.0 .... 	

Year-round 	 <10D <40b <8b 
-------
          5.1.5.1  Process Description


There  are  several  types  of wetlands (as mentioned in Chapter 2)  with
varying  amounts  of organic substrate and vegetative growth and varying
degrees  of  soil  moisture.   They  require  low-lying,  usually level,
saturated  land,  sometimes  partially  or  intermittently  covered  with
standing water.  In wetland application systems, wastewater is renovated
by the soil, plants, and microogranisms as it moves through and over the
soil  profile.   Wetland  systems  are somewhat similar to overland  flow
systems  in  that  most of the water flows over a relatively impermeable
soil  surface  and  the renovation action is more dependent on rnicrobial
and plant activity than soil chemistry.
          5.1.5.2  Hydraulic Loadings


Items to be considered in selecting the hydraulic loading include:

     1.   Detention time of applied wastewater

     2.   Rate  of  water  loss  from system by planned overflow or slow
          seepage

     3.   System  upsets  due to washouts by precipitation or wastewater
          applications


          5.1.5.3  Nitrogen Management


For  a  wetland system, the following mechanisms should be considered as
factors having an influence on nitrogen balance:

     1.   Denitrifi cation

     2.   Above ground and below ground plant uptake

     3.   Dilution

     4.   Sorption with living or dead material


The biomass productivity of wetland systems has been reported to be 4 to
5  tons/acre  (8  to 10 Mg/ha) in Wisconsin marshes, with other reported
values  up to 6.7 to 8 tons/acre (15 to 18 Mg/ha) [30].  The total  plant
nitrogen  uptake  is extremely high since nitrogen content of the plants
may  be from 2.0 to 2.5%; however, the below ground portion of the  plant
may  contain  4  to 6 times as much biomass as the above ground portion.
Thus, the majority of the nitrogen content in the system is released and
recycled  rather  than  being  available  for  removal   by harvest.  The
seasonal  uptake  and  release  by  perennial  and  annual vegetation is
                                 5-23

-------
influenced by the nitrogen cycling.  In general,  natural  wetlands  can  be
classified  as  low in nitrogen availability, because  their  high organic
content  can  serve as a nitrogen sink.  Managed  wetlands can  facilitate
biomass  production  and  harvesting  to  provide  an  effective nitrogen
removal mechanism.
The  schematic diagram presented in Figure 5-5 illustrates  the  principal
nitrogen  transformations  occurring in a wetland  system.   The  overlying
water  and  underlying  organic  soil  form an aerobic-anaerobic  double-
layer, thus  providing  ideal  conditions  for biological nitrification-
denitrifi cation reactions to occur.
                              FIGURE 5-5

                  PRINCIPAL NITROGEN TRANSFORMATIONS
                           IN WETLANDS [20]
APPLIED NITROGEN
(MOSTLY NH4)
  ORGANIC
  MATTER
   SOIL
                                                                  OXIDIZED
£~ NH -NO.  2\\r.'NITRIFICATION.;
    4

     ^"^-.^
                                                                  REDUCED
          5.1.5.4  Climatic Considerations
Climatic  considerations  for  wetland  systems   are   not  well  defined.
Although  wetland  systems  have been utilized in locations  from Florida
[28] to the Canadian Northwest Territories [26],  the mechanisms  involved
                                  5-24

-------
in  retention  or removal  of each wastewater component are uncertain.   A
wetland  system in Wisconsin used for wastewater application is shown  in
Figure 5-fa.
                               FIGURE  5-6

                WETLAND  SYSTEM  AT  BRILLION MARSH, WISCONSIN
          b.1.5.5  Phosphorus Management
Within  the  range  of wetland system types, the phosphorus removals can
vary  considerably.   For  peatlands,  Stanlick  reports  99X removal of
phosphorus  [27].   In  Wisconsin,  using  man-made and natural  marshes,
Spangler  et  al.  report  30 to 40% removal on a year-round oasis [23].
              capabilities are generally high during the growing season,
              soils  have  a  high  cation  exchange capacity (about lOb
             and wetland plants account for luxury uptake of phosphorus.
             the above ground plant portions will remove some phosphorus
from  the  system;  however,  release from the below ground portion will
occur during the nongrowing season.
The  removal
because  the
meq/100 g)
Harvest  of
                                  5-25

-------
          5.1.5.6  Trace Elements Removal
Although extensive research has not been done with wetlands, the results
of  research  from  metal  accumulation  in lake and river sediments are
generally  applicable.   Organic  soils  may  have  high cation exchange
capacities  so retention should be excellent; however, the effects of pH
on retention must be considered.
          5.1.5.7  Microorganism Removal
The  removal  of  pathogenic  microorganisms  depends on the pathway  for
water  leaving  the site.  Systems that have no overflow and function by
water  seepage  through  a  slightly  permeable soil  will  have excellent
removal  of  all  microorganisms, due to physical  entrapment and die-off
mechanisms.   Surface overflow systems offer a less positive removal, so
natural  die-off  as  a  function  of detention time, climate, and other
environmental factors must be assessed.
5.2  Preapplication Treatment
The design of preapplication treatment facilities involves three steps:

     1.   Determine  the  level   of  treatment required for the selected
          land treatment process and site conditions

     2.   Select a treatment system capable of meeting this level

     3.   Establish  design  criteria and perform detailed design of the
          selected treatment system
Only  the  level   of  treatment  required will  be discussed,  because  the
second  and third items are standard engineering  procedures that are  not
unique to land treatment.
     5.2.1   Determination of Level  Required


In  general,  the  level   of  preapplication  treatment  required  is an
internal  process  decision  made  by   the  designer  to  ensure optimum
performance of the land treatment process.  Preapplication treatment may
be   necessary   for  a  variety  of  reasons   including  (1)   improving
distribution system reliability, (2) reducing  the potential  for nuisance
conditions,   (3) obtaining   a   higher  overall  level  of  wastewater
treatment,   (4) reducing   soil   clogging,   and  (5)  reducing the risk of
public  health impacts.  The need for  preappl ication treatment to reduce
impacts on  various system components is summarized in Table 5-13.
                                   5-26

-------
                                TABLE 5-13

                     NEED FOR PREAPPLICATION TREATMENT
System
component
Storage

Distribution
system

Crops


Hydraulic
loading
Public access

Potential problems
Odors and solids
accumulation

Solids deposition
orifice clogging

Limited selection


Reduced loading
rate for rapid
infiltration
Health risk due
to contact

Level of treatment and mitigating measures
Screened3 - add aerators
Primary - add aerators'3
Biological
Screened - velocity control and larger orifice
Primary - velocity control
Biological
Screened - limit to high tolerance crops (i.e.,
Primary - limit to feed, seed, and fiber crops
Biological - disinfect to suit individual needs
Screened - increased basin maintenance
Primary - increased basin maintenance or use of
Biological



nozzles

grass)


vegetation
Screened - posting and fencing or buffer zones or disinfection
Primary - posting and fencing or buffer zones or disinfection
Biological - disinfect for public access areas

 a.  Bar screens and comminution.

 b.  Only for short-term (less than a month) storage.
           5.2.1.1   Impacts During  Storage
The  primary consideration  for preapplication treatment prior to storage
is reduction of the  potential  for nuisance conditions.  This may require
reduction in the  settleable solids and  organic content of the wastewater
to  levels  achievable  with  primary  treatment.   This will  minimize the
possibility  of   nuisance   conditions   developing  in the storage lagoon.
Such  factors  as  climate,  length of  storage, and reservoir design will
determine  the  necessary   level   of   BOD  reduction.  Storage reservoirs
provide   additional   treatment    through  further  biological   action,
deposition of solids, and long-term pathogen  die-off [31].   Supplemental
aeration  could   be  provided   in the  reservoir to meet excessive oxygen
demand.  An alternative concept would  be to  design the storage lagoon to
double  as  a  deep  facultative   lagoon.  Disinfection prior to storage
should  not  be necessary as long  as public  access to the storage lagoon
is restricted.
                                  5-27

-------
          5.2.1.2  Impacts on Transmission


Although transmission of wastewater to  the  application  site will  usually
not  govern  the  level   of  preapplication  treatment,   the  method   of
transmission  should  be taken into consideration.   For systems  in which
wastewater  is  to  be  pumped  to  the  application site  and  no other
preapplication  treatment is required,  coarse screening,  degritting, and
comminution should be included to avoid excessive wear  on the equipment.


          5.2.1.3  Impacts on Distribution  Systems


Preapplication   treatment   considerations   for   surface  distribution
techniques  include coarse and settleable solids removal  to avoid solids
deposition  in  ditches  and  laterals.  The need  for  disinfection will
depend  on  the  possibility  of  public contact   with the distribution
system.


Different  criteria  apply  to sprinkler distribution systems.   To avoid
plugging  of  nozzles,  it  has  been  recommended   that the  size of the
largest  particle  in  the applied wastewater be less than one-third the
diameter  of  sprinkler  nozzles [11].   Removal of  coarse and settleable
solids  as  well  as  grit  and  any oil and grease should be a minimum
preapplication  treatment level  to maintain reliability in systems using
sprinkler distribution.


          5.2.1.4  Impacts on Slow Rate Application


For  slow  rate  systems,  hydraulic or nitrogen loadings will generally
govern  the  system  performance.   Thus, from the  standpoint of process
performance  and  soil  matrix  impacts, preapplication treatment  for
reduction of organics and suspended solids  is not necessary.  Industrial
wastewaters  with  high  organic  strength   have  been   applied   to land
successfully,  and  data  are  available to indicate that no  significant
difference  in  overall   performance was obtained  when both  primary and
secondary effluent were applied under similar conditions [32].
Where  the method of application is by sprinkling,  limits  on  aerosol  and
mist  drift  should  be  considered.   Preapplication   treatment  such as
primary  settling,  secondary  treatment,   and  disinfection all serve to
reduce  the  bacterial   content  of  the   effluent   and hence reduce  the
numbers  of  aerosolized  bacteria.  The  need for secondary treatment or
disinfection  must  be  evaluated  on  a   case-by-case  basis  taking into
account (1) the population density of the  area,  (2)  the degree of public
access  to the site, (3) the  relative  size of the   application area,
(4) the feasibility  of  providing buffer  zones  or  plantings  of trees or
shrubs, and (5) the prevailing climatic conditions.
                                   5-28

-------
For forage  crop  irrigation,  the need for disinfection can  be balanced
against  the  exposure  risk  to  the  public  or  grazing   animals  from
pathogens in municipal wastewater.  On the basis of a limited comparison
of  land  treatment  with  conventional  treatment and discharge,  it was
concluded  that  the  relative  risks to the public were essentially the
same  [33].   Primary  treatment followed by surface application to  land
that  is  fenced  has been considered adequate to minimize  health  risks.
For  application  to  parks,  golf  courses, and areas of public access,
biological treatment followed by disinfection is often practiced.


          5.2.1.5  Impacts on Rapid Infiltration Application


The potential for soil clogging is higher for rapid infiltration systems
than for slow rate systems due to greater hydraulic loading rates.   As  a
minimum, primary treatment to remove coarse and settleable solids  should
be  included  as  preapplication  treatment.   Reduction  of   solids to
secondary levels will increase-the allowable hydraulic loading rates for
rapid  infiltration  systems  and  a balance can be achieved  between the
degree  of  preappl ication  treatment  and  the  hydraulic  loading  rate.
Algae  carryover  from  holding  ponds  or  lagoons  will  increase   the
potential  for  soil  clogging.  The use of in situ pilot studies may be
required  to  develop  soil  response  relationships  between  hydraulic
loading and wastewater solids and organic levels [11].


          5.2.1.6  Impacts on Overland Flow Application
Because  overland flow treatment is basically a surface phenomenon,  soil
clogging  is  not  a problem, and high BOD and suspended solids removals
have  been  achieved  with  systems  applying  raw  comminuted municipal
wastewater [34] and industrial wastewater with 616 mg/L BOD and 263  mg/L
of suspended solids [35].  Thus, preappl ication treatment for removal  of
organics  and  solids  would be necessary only to the extent required  by
other system components.  The need for predisinfection would be governed
by  consideration  of  the method of distribution.  Low-pressure,  large-
droplet, downward sprinkling nozzles and bubbling orifices or gated  pipe
distribution  should  not  require  predisinfection  if public access  is
controlled.   Postdisinfection of the wastewater runoff may be required.
Because  overland  flow  systems  are  less  effective  for  removal   of
phosphorus  than  other land treatment methods, preapplication treatment
to enhance overall phosphorus removal may be necessary if a low level  is
required in the collected runoff.
     5.2.2  Industrial Pretreatment
Pretreatment of industrial wastewaters discharged into municipal  systems
may  be  required  for  several reasons, including (1) protection of the
collection  system;  and  (2) removal  of constituents that would  have an
                                    5-29

-------
adverse  impact  on  the  treatment   system  or   would   pass  through the
treatment  process  relatively  unchanged, causing  unacceptable  effluent
quality.   General  guidelines  for   pretreatment  of   industrial wastes
discharged  to  municipal  systems using  conventional  secondary treatment
have been published by the EPA [36].


Pollutants  that  are  compatible with  conventional  secondary treatment
systems  would  generally  be compatible  with land treatment  systems.  As
with  conventional  systems, pretreatment requirements  will  be necessary
for  such  constituents  as  fats,   grease,   and  oils,  and  sulfides to
protect  collection  systems  and treatment  components.    Pretreatment
requirements  for  conventional   biological  treatment  will  also protect
land treatment processes.


High  levels  of  sodium  decrease   the  soil permeability.   Pretreatment
requirements  may  be necessary  for  industrial wastes high in sodium, if
the  SAR  of  the  total  wastewater might be increased  to  unacceptable
level s.
Plant  toxicity  from  metals is discussed  in Appendix  E  and  recommended
maximum  concentrations  of trace elements  in irrigation  water  have been
previously presented in Table  5-4.    Concern   over   accumulation  in  the
food  chain  is  greatest  for cadmium,  as  discussed  in Appendix E.   The
potential   for groundwater contamination from trace elements  is greatest
for  rapid infiltration systems, although the ability of  soils  to  remove
and accumulate heavy metals from such  systems has  been  demonstrated [13,
37].
5.3  Storage
There  is  a  need for storage in many  land  treatment systems  because of
the  effect  of  climate on treatment or  an  imbalance between  wastewater
supply  and  application.  Slow rate and  overland  flow systems may cease
operation  during adverse climatic conditions whereas rapid  infiltration
systems  can  usually  continue operation year-round.  An  alternative to
storage may be seasonal  discharge to surface waters.
     5.3.1  Determining Storage Needs
The National  Climatic Center in Asheville,  North  Carolina,  has  conducted
an  extensive  study of climatic variations throughout  the  United  States
and  the  effect  of  these  variations  on  storage  requirements for  soil
treatment  systems [38].  Three computer programs,  as presented in Table
5-14,  have  been  developed  to estimate the  storage days  required  when
inclement weather conditions preclude  land  treatment system operation.
                                   5-30

-------
                                TABLE 5-14

               SUMMARY  OF  COMPUTER PROGRAMS FOR DETERMINING
                      STORAGE  FROM CLIMATIC VARIABLES
EPA
program Applicability
EPA-1 Cold climates
Variables
Mean temperature,
Remarks
Uses freeze index
           EPA-2


           EPA-3
Wet climates
rainfall, snow depth

Rainfall
Storage to avoid
surface runoff
Moderate climates Maximum and minimum    Variation of EPA-1
              temperature, rainfall, for partly favor-
              snow depth          able conditions
Depending  on   the   dominant climatic conditions of a region, one of the
three  computer  programs  will  be most suitable.  The program best suited
to a particular  region  is shown  in Figure 5-7.   The maximum storage days
over  the  period   of   record  is calculated as well as storage days for
recurrence intervals of 5,  10,  and 50 years.
The  validity of any  one  of  the  computer storage programs will depend on
the presence of adequate  data.   The quality,  completeness, and length of
record are all important.  Assigning threshold values and the confidence
level  of  the output must be considered carefully in order to provide a
realistic  estimate of  required  storage.  To  use these programs, contact
the  National  Climatic   Center   of the National Oceanic and Atmospheric
Administration in Asheville, North Carolina 28801; a fee is required.
          5.3.1.1   Determining  Storage in Cold Climates
The  operation  of   a   slow rate  or overland flow system is likely to be
affected  adversely  if severe  cold weather prevails for long periods (2
to  4  months).   If   annual  crops  are being irrigated, then the growing
season  will determine the  storage  requirement.   However, if perennials,
such   as   grasses    and   woodlands,   are  irrigated,  then  wastewater
application  will  normally  be  stopped only by frozen soil conditions.
The  EPA-1  program  computes a  "freezing index"  which provides a measure
of  the  intensity and duration of  cold periods  that are likely to occur
in  the  Northeast,  the northern  half of the Midwest, and parts of the
Rocky  Mountain  area   (see  Figure 5-7).  When  the index reaches 200 to
300,  the  ground  is  assumed to  be frozen and wastewater application is
not  recommended  [39].   Limitations   to  the use of the freezing index
include:   lack  of  soil   temperature  data, yearly winter temperature
variations,  and  differences  in  design  and  operating  practices for
existing land treatment systems.
                                    5-31

-------
                                                         FIGURE  5-7
                             DETERMINATION OF STORAGE BY  EPA COMPUTER  PROGRAMS  AND  WATER  BALANCE
                                          ACCORDING TO CLIMATIC  CONSTRAINTS  [11,  38]
en
i
to
IND
WATER BALANCE

      &/
    EPA-3

-------
EPA-1   also   computes  storage  based  on  the favorable/unfavorable day
analysis   by   assigning  threshold values to (1) mean daily temperature,
(2)  daily  precipitation,  and (3) snow cover.  The storage requirement is
increased  by one day's flow on days designated as unfavorable according
to   the  threshold  values.  On a favorable day, storage is reduced by a
fraction   of   one  day's   flow—the  drawdown  rate.   A range of common
threshold  values  used  as  input  to  the  EPA-1  program is listed in
Table 5-15.
                                TABLE 5-15

              THRESHOLD VALUES FOR THE EPA-1 STORAGE PROGRAM
                                           Favorable day
                          Parameter          threshold values


                    Mean daily temperature, °F         >25-32

                    Daily precipitation, in.         <0.5-1.0

                    Snow cover, in.                 <1.0

                    Drawdown rate, % of average
                    flow                "         50-25
                    1°F = 1.8°C + 32
                    1  in. = 2.54 cm
           5.3.1.2   Determining  Storage in Moderate Climates


To  estimate  storage  for moderate climatic zones where winter conditions
are less severe  such  as  the   mid-Atlantic states (see Figure 5-7), EPA-3
is  recommended.    This   program  is  more  flexible  than EPA-1 in that
minimum  and maximum  daily temperatures are examined instead of the mean
daily  temperature.    Both   temperature thresholds must be reached for a
day  to  be   favorable.   However,  if  the maximum daily temperature is
exceeded,  but the  minimum temperature is below the lower threshold, the
program  assumes  that  it   is   warm enough to permit operation during a
portion of the day, i.e., a  partly favorable day.  EPA-3 is organized so
that  on   partly  favorable   days, storage is automatically increased by
some  fraction  of  the   daily   flow.    The precipitation and snow cover
thresholds  and  the   drawdown   rate  act as they do for EPA-1.  Weather
station  data for the above  parameters are examined during the months of
November   through   April  for  the  available period of record (20 years
minimum).


The  drawdown  rate,  as  used in EPA-3,  is the amount of water applied on
favorable  days  in   addition  to  the  average daily flow.  In moderate
climates,  this  parameter can  significantly reduce storage requirements
                                   5-33

-------
but  at  the  expense of increasing land requirements.  Availability and
cost  of  the  additional land will determine how much wastewater can be
applied from storage.


          5.3.1.3  Determining Storage in Wet Climates
In wet regions where a high percentage of the annual precipitation is in
the  form of rain and the mean daily temperature seldom drops below 32°F
(0°C),  the  EPA-2  storage  program should be used.  EPA-2 accounts for
prolonged  wet  periods  where  rain  can occur almost daily between the
months  of November and April.  Regions where prolonged wet spells limit
the application of wastewater are at locations along the Gulf states and
the  Pacific  Northwest  Coastal   Region.  Daily climatological  data are
examined  in  an attempt to identify days when the soil is saturated and
an  application  of wastewater would result in unwanted runoff.   Any day
where  runoff  occurs is defined as unfavorable and considered a storage
day.
The  EPA-2  program  is  an  outgrowth  of  work  by Palmer to determine
conditions  of  meteorological   drought  for agricultural purposes [4U].
The  rate  at  which excess soil moisture is depleted from the soil (the
soil  drying  rate)  is approximated by the EPA-2 program to account for
the  long-term  effects of extremely heavy rainfall.  The program can be
modified to suit different soil conditions.
          5.3.1.4  Determining Storage in Warm Climates
In warm climates, such as the semiarid and arid southwest United States,
the  climatic  constraints to application of wastewater are usually very
small  (1  to  5 days).  In these situations total storage may depend on
the  balance between water supply and application rate and the amount of
certain  wastewater  constituents, e.g., nitrogen that can be applied to
the soil  without exceeding groundwater quality restrictions.
An  irrigation water balance, which also considers nitrogen loading, can
be  used  to  estimate  cumulated storage in warm climates for slow rate
systems.   The  water  balance consists of the elements in the following
equation:

         Design      + W"tewfer = Evapotranspiration + Percolation + Runoff     (5-4)
         precipitation  applied       r     r                            \~> -r/


A  monthly  evaluation  of  water  balance  is suggested due to seasonal
variations  in  component factors.  Of all the factors, precipitation is
the most unpredictable.  A range of values that might be encountered can
be  established  on  the  basis  of a frequency analysis of wetter-than-
normal  years  (the  wettest  in 10, 20, or 25 years may be reasonable).
                                   5-34

-------
When  using  the  water  balance  to  estimate  storage,  the recurrence
interval for precipitation and evapotranspiration should be the same.


An  example  of  a monthly irrigation water balance to determine storage
requirements  for  a  1  Mgal/d  (43.8 L/s) slow rate system is shown  in
Table   5-16.    This   water  balance  assumed  (1)  precipitation and
evapotranspiration  data  for  the  wettest  year in 25, (2) nitrogen  is
limiting  and  separate  calculations  show  that  120 acres (48 ha) are
required,  (3)  a perennial grass is  grown  and  irrigated  year-round,
(4)   tailwater   runoff  from  surface  application  is  contained and
reapplied,  and  (5)  the storage reservoir is empty at the beginning  of
the water year.


The  maximum  storage  would  be 22.7 in. (58 cm) in the month of March,
calculated  for  an  application area of 120 acres (48 ha), yielding the
required storage volume of 227 acre-ft (280 000 m3) or 74 days  flow   at
1 Mgal/d (43.8 L/s).
          5.3.1.5  Irrigation and Consumptive Use Requirements
In  mild  climates,  storage  requirements  could  be  governed   by   the
management  of  crops  that  are  to  be   grown.   The  irrigation   and
consumptive  use  requirements  shown in Table 5-17  for the Bakersfield,
California,  slow rate system illustrate how storage is affected  by  crop
selection.   It should be pointed out that only a portion of the  applied
wastewater   is   actually   consumed   by   the   crops   (or lost  by
evapotranspiration).   Some  of  the  wastewater will be lost by  seepage
from  irrigation  ditches,  from surface runoff, and by deep percolation
below  the  root  zone  in  the field.  This is reflected in Table 5-17,
where  irrigation  requirements are shown to be greater than consumptive
use  values.   The  U.S.  Department of Agriculture has estimated  that on
the  average  about  47%  of the irrigation water enters the soil and is
held  in  the  root zone where it is available to crops.  It also points
out  that  it is possible to attain irrigation efficiencies of 70 to 75%
by  proper  selection,  design,  and operation of the irrigation  system,
including provision for tailwater return [42].


There  are  several  months  listed  in  Table  5-17  when  there  is no
irrigation  requirement although consumptive use is  indicated. In these
cases,  it  is  assumed  that  crop  water  needs  are being supplied by
effective  growing season precipitation and carryover soil  moisture  from
winter rains, or pre-irrigation.
                                  5-35

-------
                                         TABLE 5-16

                   EXAMPLE OF STORAGE DETERMINATION FROM  A WATER
                               BALANCE  FOR  IRRIGATION  [41]
                                           Inches
Month
(1)
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Evapotrans-
pi ration3
(2)
2.3
1.0
0.5
0.2
0.3
1.1
3.0
3.5
4.8
6.0
5.7
3.9
Allowable
percolation'5
(3)
10.0
10.0
5.0
5.0
5.0
10.0
10.0
10.0
10.0
10.0.
10.0
10.0
Water
losses0
(2M3)
= (4)
12.3
11.0
5.5
5.2
5.3
11.1
13.0
13.5
14.8
16.0
15.7
13.9
Precipitation3
(5)
1.6
2.4
2.7
3.0
2.8
3.4
3.0
2.1
1.0
0.5
1.1
2.0
Water
deficitd
(4)-(5)
= (6)
10.7
8.6
2.8
2.2
2.5
7.7
10.0
11.4
13.8
15.5
14.6
11.9
Wastewater
available6
(7)
9.3
9.3
9.3
9.3
9.3
9.3
9.3
9.3
9.3
9.3
9.3
9.3
Change in
storage^
(7)-(6)
= (8)
-1.4
0.7
6.5
7.1
6.8
1.6
-0.7
-2.1
-4.5
-6.2
-5.3
-2.6
Total
storage
(9)
0
0.7 ,
7.2
14.3
21.1
22.7
22.0
19.9
15.4
9.2
3.9
1.3
Total
annual
32.3
105.0
                                  137.3
25.6
111.7
111.8
a.  Precipitation and evapotranspiration data are entered into columns  5 and 2, respectively.

b.  On the  basis of the nutrient balance to satisfy groundwater quality standards, the design
    allowable percolation rate  is  10 in./month from March through  November and 5 in./month for  the
    remaining months (column  3).

c.  The water losses (column  4) are found by summing evapotranspiration and percolation.
d.  The water deficit (column 6) is the difference between the water losses and the precipitation.

e.  The wastewater available  per month (column 7) is

        . Wastewater _ 1 Mgal/d  x 30.4 d/month x 36.3 acre-in./Mgal
         available                  120 acres

f.  The monthly change in storage  (column 8) is the difference between  the wastewater available
    (column 7) and the monthly  water deficit (column 6).

1  in.  - 2.54 cm
1  Mgal/d =  43.8 L/s
1  acre = 0.405 ha
                                              5-36

-------
                                          TABLE  5-17
      IRRIGATION  AND  CONSUMPTIVE USE  REQUIREMENTS  FOR SELECTED  CROPS
                         AT BAKERSFIELD,  CALIFORNIA  [43, 44]
                                Depth of  Water  in  Inches
                                     Double crop
        Pastures or alfalfa3    barley  and grain sorghum          Cotton0               Sugar beets"
Month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Consumptive
use
0.9
2.0
3.8
5.2
7.0
8.6
9.4
8.7
5.8
4.3
2.0
1.0
Irrigation
requirements
1.2
2.7
5.1
7.0
9.4
11.5
12.6
11.7
7.8
5.8
2.7
1.3
Consumptive
use
1.0
2.0
3.8
5.2
2.6

4.5
8.0
6.0
3.0

1.0
Irrigation
requirements

....
6.0
6.0

10.0
7.0
12.0
9.0


10.0
Consumptive
use

....

0.6
1.2
3.6
7.2
8.4
6.0
2.5

....
Irrigation
requirements

15e



5
12
12




Consumptive
use



1.0
2.5
5.0
7.0
8.0




Irrigation
requirements


5.0
9.0
5.0
9.0
7.5
4.5


6.0f

Total     58.7         78.8         37.1         60.0         29.5         44          23.5        46.0

a.   Estimated maximum consumptive use (evapotranspiration) of water by mature crops with nearly complete ground-
   cover  throughout the year.
b.   Barley planted in November-December, harvested in June.   Grain sorghum planted June 20-July 10, harvested
    in November-December.
c.   Rooting depth of mature cotton: 6 ft.  Planting dates:   March 15  to April 20.  Harvest:  October, November,
    and December.
d.   Rooting depth:  5 to 6 ft.   Planting date:  January.  Harvest: July 15 to September 10.
e.   Pre-irrigation should wet soil to 5 to 6 ft depth prior  to planting.
f.   Pre-irrigation is used to ensure germination and emergence.  First crop irrigations are heavy in order to
    provide deep moisture.
1  in. = 2.54 cm
1  ft = 0.305 m
                                                5-37

-------
     5.3.2  Storage Reservoir Design


Most  agricultural   reservoirs  are   constructed   of   simple homogeneous
(uniform  materials)   earth embankments, the design of which conforms to
the  principles  of small  dam design.  Depending on the magnitude of the
project,  state  regulations  may  govern the design.  In California for
example,  any  reservoir with embankments higher than 6 ft (1.8 m) and a
capacity  in  excess   of 50  acre-ft   (61 800 m3)  is  subject  to state
regulations  on  design  and  construction  of  dams,  and plans must be
reviewed  and  approved by the appropriate agency  [45].  Design criteria
and  information  sources are included in the U.S. Bureau of Reclamation
publication,  Design   of  Small  Dams  [46].    In  many cases, it will be
necessary  that a competent soils engineer be consulted for proper soils
analyses and structural  design of foundations and  embankments.
5.4  Distribution
The most common distribution techniques  for land application fall within
two  major  categories—surface   and   sprinkler--the  selection of which
depends  on the objectives of the project and the limitations imposed by
physical conditions such as topography,  type of soil, crop requirements,
and level  of preapplication treatment.


Surface  distribution  employs  gravity  flow from piping systems or open
ditches  to  flood  the  application   area with several inches of water.
Surface distribution is more suited to soils with moderate to low intake
rates.  Control of runoff is usually more of a consideration for surface
distribution  than  for  sprinkling,   as applications of 2 in. (5 cm) or
less  by  surface methods are difficult  to apply uniformly.  Graded land
is essential to proper performance of  a  surface system.
Sprinkler  distribution  simulates   rainfall  and  is less susceptible to
topographic constraints than  surface methods.   It  is particularly suited
to  irrigation  of  both  highly  permeable and  highly impermeable soils.
Sprinkler  distribution  may   be  used   to irrigate most crops and, when
properly  designed,   provides  a  more  uniform  distribution of water and
greater flexibility  in range  of application rates  than  is available with
surface  distribution.   Limitations to sprinkling include adverse wind
conditions,   clogging   of  nozzles with  solids,  and  preapplication
treatment   requirements.    Sprinkling   also   involves  a   significant
utilization  of equipment and its capital costs are significantly higher
than those for surface distribution.
                                  5-38

-------
For all types of distribution systems, the maximum flow requirement of  a
given system and field area is referred to as the system capacity,  which
is computed by the formula:
                                                          (5-5)
where Q = discharge capacity, gal/min (L/s)
      C = constant, 453 (28.1)
      A = field area, acres (ha)
      D = gross depth of application, in. (cm)
      F = number of days to complete one cycle
      H = number of operating hours
The  system  capacity  is  useful   for  determining mainline sizes,  pump
capacities,  storage  requirements, and operating time requirements.   If
several  sites  are involved with different loading requirements,  system
capacities must be computed separately within the same period of time  to
determine total system capacity.
     5.4.1  Surface Systems


Surface  distribution  methods  include  ridge  and  furrow  irrigation,
surface  flooding  (border strip)   irrigation, infiltration basins,  and,
overland  flow.   The  distinguishing physical features of these methods
are  illustrated  in Figure 5-8.   Variations of methods employed in  crop
irrigation  and  the  suitability   of  each  to  conditions  of use are
summarized  in Table 5-18.  Similar criteria for the surface application
methods  not  normally associated  with crop irrigation are summarized in
Table 5-19.
          5.4.1.1  Ridge and Furrow Irrigation


Ridge and furrow irrigation consists of running irrigation streams  along
small  channels  (furrows)  bordered  by raised beds (ridges)  upon  which
crops are grown.  Furrows may be level  or graded,  straight or  contoured.
A  similar  method  is corrugation irrigation, which consists  of  furrows
excavated  from  the  surface without creating raised beds. To simplify
this  presentation,  only  straight,  graded ridge and furrow  irrigation
will  be  referred  to  hereafter,  as  its  design  considerations  are
applicable to all these methods.
Intake  characteristics  for  furrow  irrigation  are distinguished  from
those  for  border  and  sprinkler  irrigation  because  the  water  only
partially  covers  a  given  field  area,   and  moves  both downward and
outward.   Intake characteristics are best determined by  inflow-outflow
                                5-39

-------
                    FIGURE 5-8

              SURFACE DISTRIBUTION METHODS
               (a)RIDGE AND FURROW IRRIGATION


                            COMPLETELY FLOODED-
     rrr^fiTfWTtTTTi^m
             (b) FLOODING (BORDER STRIP) IRRIGATION
                      EVAPORATION
                              SURFACE A PPLICATION
ZONE OF AE
AND THE ATM

     RECHA!
                         WATER TABLE
       SURFACE
       APPLICATION
            OLD WATER TABLE

(c) RAPID INFILTRATION


  EVAPORA Tl ON




         RASS AND VEGETATIVE LITTER


                    SHEET FLOW
                    (d) OVERLAND FLOW
                       5-40

-------
                                                                                        TABLE  5-18

                                                        SURFACE  IRRIGATION  METHODS AND  CONDITIONS  OF  USE  [47]
                                                                       Suitabilities and conditions  of use
                               Irrigation
                                 method
                    Crops
                                                                      Topography
                                              Water quantity
                                                                                                                  Soils
                                                                                           .Remarks.
                               Small
                               rectangular
                               basins
               Grain, field crops,
               orchards, rice
                     Relatively flat land;
                     area within each basin  -
                     should be leve-led.
                        Can be adapted
                        to streams' of
                        various.sizes
en
 i
Large
rectangular
basins
                               Contour
                               checks
                               Marrow
                               borders up to
                               16  ft wide
                              Wide borders
                              up  to 100 ft
                              wide
Grain,  field  crops,
rice
              Orchards, grain,
              rice, forage crops
              Pasture, grain,
              alfalfa, vineyards,
              orchards
              Grain, alfalfa,
              orchards
Flat land;  must  be
graded to uniform
plane
                     Irregular land,
                     slopes less than 2%
                     Uniform slopes less
                     than 7%
                     Land graded to uniform
                     plane wi th maximum
                     slope less than 0.5%
Large flows  of
water
                        Flows greater
                        than 1  ft3/s
                        Moderately large
                        flows
                        Large flows,  up
                        to 20 ft3/s
                  Suitable for soils
                  of high or low in-
                  . take rates; should
                  not be used on
                  soils that.tend to
                  puddle
Soils of fine  tex-
ture with low
intake rates
                  Soils of medium to
                  •heavy texture that
                  do not crack on
                  drying
                  Soils of medium to
                  heavy texture
                  Deep soils of
                 . medium to fine
                  texture
High installation costs.
Considerable  labor
required for  irrigating.
When used for close-
spaced crops, a  high
percentage of land is
used for levees  and
distribution  ditches.
High efficiencies of
water use possible.
Lower installation costs
and less labor, required
for irrigation than small
basins.  Substantial
levees needed.

Little land grading
required.  Checks can be
continuously  flooded
(rice), water ponded
(orchards), or inter-
mittently flooded
(pastures).

Borders should be in
direction of  maximum
slope.  Accurate cross-
leveling required between
guide levees.

Very careful  land grading
necessary. Minimum of
labor required for irri-
gation.  Little  inter-
ference with  use of farm
machinery.

-------
                                                                            TABLE 5-18
                                                                            (Concluded)
                                                              Suitabilities and conditions  of use
ro
Irrigation
method Crops Topography
Benched Grain, field crops, Slope up to 20%
terraces
Water quantity Soils
Streams of small Soils must be suf-
to medium size ficiently deep that
grading operations
will not impair
crop growth
Remarks
Care must be taken in
constructing benches and
providing adequate drainage
channel for excess water.
Irrigation water must be
properly managed. Misuse
of water can result in
serious soil erosion.
                            Furrow
Straight
furrows



Graded
contour
furrows


Corrugations






Basin
furrows

Zizag
furrows


Vegetables, row
crops, orchards,
vineyards


Vegetables, field
crops, orchards,
vineyards


Close-spaced crops
such as grain,
pasture, alfalfa




Vegetables, cotton,
maize, and other
row crops
Vineyards, bush
.berries, orchards


Uniform slopes not ex-
ceeding 2% for cuti-
vated crops


Undulating land with
slopes up to 8%



Uniform slopes of up
to 10";





Relatively flat land


Land graded to uniform
slopes of less than }%


Flows up to
12 ft3/s



Flows up to
3 ft3/s



Flows up to
1 ft3/s





Flows up to
5 ft3/s

Flows required
are usually less
than for straight
furrows
Can be used on all
soils if length of
furrows is adjusted
to type of soil

Soils of medium to
fine texture that
do not crack on
drying

Best on soils of
medium to fine
textura




Can be used with
most soil types

Used on soils with
low intake rates


Best suited for crops that
cannot be flooded. High
irrigation efficiency
possible. Well adapted to
mechanized farming.
Rodent control is essential.
Erosion hazard from heavy
rains or water breaking out
of furrows. High labor
requirement for irrigation.
High water losses possible
from deep percolation or
surface runoff. Care must
be used in limiting size of
flow in corrugations to
reduce soil erosion. Little
land grading required.
Similar to small rectangular
basins, except crops are
planted on ridges.
This method is used to slow
the flow of water in furrows
to increase water penetra-
tion into soil .
                            1  ft3/s  =  0.028 m3/s
                            1  ft = 0.305 m

-------
                                                                   TABLE 5-19



                                     NONIRRIGATING SURFACE APPLICATION METHODS AND CONDITIONS  OF USE
tn




co
Application
method
Rapid
infiltration
Overland
flow

Vegetation
Perennial
grasses
Perennial
grasses9
Suitabilities
Topography
Relatively flat
to irregular
Uniformly graded
with slopes from
and conditions of
Water supply
May be relatively
large, soils
permitting
Moderately large
flows with high
percentage of
runoff
use
Soils
Coarse texture
and high infil-
tration rates
Limited
permeabi li ty
Remarks
Water applied on inter-
mittent basis to maintain
permeability. Often less
land preparation than
most irrigation systems.
Land must be smooth to
achieve sheet flow
without ponding .
                             a.  Suitable for continuously wet-root conditions.

-------
measurements  in  the  field.  Design  application  rates are then  based on
these   results.   Furrow  intake rates  are usually  expressed as  flowrate
(gal/min,   L/s)  per unit length (100 ft,  100 m)  of furrow.  Application
rates   are  usually  expressed  as  flowrate per furrow, or furrow  stream
size.
Other   factors  of  critical   importance  for design  of ridge and  furrow
irrigation  are:   furrow stream size  [48,  49, 50], furrow length  (Table
5-20),  furrow slope [47], and furrow spacing (Table 5-21).

                                 TABLE 5-20
      SUGGESTED MAXIMUM  LENGTHS OF CULTIVATED FURROWS FOR DIFFERENT
           SOILS, SLOPES,  AND DEPTHS OF  WATER TO BE APPLIED [47]
                                    Feet
Furro1
slope,
0.05
0.1
0.2
0.3
0.5
1.0
1.5
2.0
1 ft =
1 in.


% 3
1 000
1 100
1 200
1 300
1 300
900
800
700
0.305 m
= 2.54 cm


Avg
depth of water applied, in.
Clays
6
1 300
1 400
1 500
1 600
1 600
1 300
1 100
900

9
1 300
1 500
1 700
2 000
1 800
1 600
1 400
1 100

12
1 300
1 600
2 000
2 600
2 400
1 900
1 600
1 300

2
400
600
700
900
900
800
700
600

Loams
4
900
1 100
1 200
1 300
1 200
1 000
900
800

6
1 300
1 400
1 500
1 600
1 500
1 200
1 100
1 000

8
1 300
1 500
1 700
1 900
1 700
1 500
1 300
1 100

2
200
300
400
500
400
300
250
200

Sands
3
300
400
600
700
600
500
400
300

4
500
600
800
900
800
700
600
500

5
600
700
1 000
1 300
1 000
80.0
700
600

                                 TABLE 5-21
                OPTIMUM  FURROW OR CORRUGATION SPACING  [49]
                                                    Optimum
                            Soil condition           spacing, in.

                   Coarse sands  - uniform profile          12
                   Coarse sands  - over compact subsoils      18
                   Fine sands to sandy loams - uniform      24
                   Fine sands to sandy loams - over
                   more compact  subsoils                 30
                   Medium sandy-silt loam - uniform         36
                   Medium sandy-silt loam - over
                   more compact  subsoils                 40
                   Silty clay loam - uniform              43
                   Very heavy clay soils - uniform         36

                   1  in. = 2.54  cm
                                    5-44

-------
The  distribution  systems  most  commonly  used   for   ridge   and furrow
irrigation  consist  of open ditches with siphon  pipes  (see Figure 5-9),
or gated surface piping system (see Figure 5-10).   The  open ditch system
may  be  supplied by distribution ditches or canals with  turnouts, or by
buried  pipelines  with  valved  risers.    Gated   surface piping systems
generally  consist of aluminum pipe with  multiple gated outlets, one per
furrow.   The  pipe is connected to hydrants which are  secured to valved
risers from underground piping systems.


                                FIGURE  5-9

                 PLASTIC SIPHON TUBE FOR  FURROW  IRRIGATION
          5.4.1.2  Surface Flooding Irrigation
Surface  flooding irrigation consists of directing  a  sheet flow  of water
along  border  strips,  or  cultivated  strips of lana  bordered  by small
levees.   This method is particularly suited to close-growing  crops  such
as  grasses that can tolerate periodic inundation at  the  ground  surface.
The  border strips usually have slight, if any, cross slopes,  and nay be
level  or  graded  in  the direction of flow.   Border strips may also be
straight  or  contoured.   For  purposes of illustration, only straight,
graded  border  irrigation will be included in the  design considerations
that  follow.   Detailed  design procedures developed by  the SCS for the
various  types  of borders are given in Chapter 4,  Section 15  of the SCS
Engineering Handbook [51].
                                  5-45

-------
                              FIGURE 5-10

         ALUMINUM HYDRANT AND GATED PIPE FOR FURROW IRRIGATION
             £ •       "* - -
Application  rate  for border irrigation is dependent on  the  soil  intake
rate  and  physical  features of the strip.   Water is applied  in  the  same
manner  as  in  ridge  and  furrow  irrigation.   However,   the stream  is
normally  shut  off  when it has advanced about  75% of the  length  of the
border.   The  objective  is  to  have sufficient water remaining  on the
border  after  shutoff to irrigate the remaining length of  border  to the
proper  depth with very little runoff.  Theoretically, it is  possible  to
apply  the water nearly uniformly along the border using  this technique.
However,  actually  achieving  uniform  distribution with minimal  runoff
requires  a  good  deal  of  skill  and  experience  on  the  part  of the
operator.   Minimization  of  runoff  is  somewhat  less  critical   when
tailwater return systems are used.
The  widths  of  border strips are often selected for compatibility  with
farm  implements,  but  they also depend to a certain extent upon  slope,
which  affects the uniformity of distribution across the strip.  A guide
for  estimating strip widths based on grades in the direction of flow  is
presented in Table 5-22.


Other  design  factors for a border strip system are similar to  those  of
ridge  and  furrow  irrigation.  These factors include intake character-
istics [51],  border  strip  lengths  and  slopes (Table 5-23 and  5-24).
Another  factor  influencing  design  is  surface  roughness, which  is a
measure of resistance to flow caused by soil and vegetation.
                                 5-46

-------
                               TABLE .5-22

               RECOMMENDED MAXIMUM BORDER STRIP WIDTH  [51]
Irrigation
grade, %
0
0.0-0.1
0.1-0.5
0.5-1.0
1.0-2.0
2.0-4.0
4.0-6.0
Maximum strip
width, ft
200
120
60
50
40
30
20
                           1 ft = 0.305 m
                               TABLE 5-23

              DESIGN STANDARDS FOR BORDER STRIP  IRRIGATION,
                         DEEP ROOTED CROPS  [47]
Soil type and
infiltration rate
Sandy


Loamy
1 in.

Sandy
0.75

Clay
, 1+ in./h


sand, 0.75-
/h

loam, 0.5-
in./h

loam, 0.25-
0.5 in./h

Clay,
0.25

0. 10-
in. /h
Slope, *
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.

2-0.
4-0.
6-1.
2-0.
4-0.
6-1.
2-0.
4-0.
6-1.
2-0.
4-0.
6-1.
2-0.

4
6
0
4
6
0
4
6
0
4
6
0
3

Unit flow
per foot, of
strip width,
ft3/s
0
.11-0.
0.09-0.
0
0
0
.06rO.
.07-0.
.06-0.
0.03-0.
0
0
0
0
0
0
0

.06-0.
.04-0.
.02-0.
.03-0.
.02-0.
.01-0.
.02-0.

16
11
09
11
09
06
08
07
04
04
03
02
04

Avg deptf
of water
applied, •
4
4
4
5
5
5
6
6
6
7
7
7
8

i Border
in. Width,
40-100
30-40
20-30
40-100
25-40
25
40-100
20-40
20
40-100
20-40
20
40-100

strip, ft
„ Length
200-300
200-300
250
250-500
250-500
250
300-800
300-600
300
600-1 000
300-600
300
1 200+

         1  ft3/s = 28.3 L/s
         1  in.  = 2.54 cm
         1  ft = 0.305 m
The distribution  systems   for  surface  flooding  irrigation are basically
the  same  as  for  ridge   and   furrow  irrigation.   A common practice in
system  layouts  is  to  locate the vertical  risers  from buried lines at
spacings  equal  to  the  border strip  widths.   Thus, one valve supplies
                                  5-47

-------
                              TABLE 5-24

             DESIGN STANDARDS FOR BORDER STRIP  IRRIGATION,
                       SHALLOW ROOTED CROPS [47]
Soil profile
Clay loam, 24 in.
deep over per-
meable subsoil
Clay, 24-in.
deep over per-
meable subsoil
Loam, 6-18 in.
deep over
hardpan
Slope, %
0.15-0.6
0.6-1.5
. 1.5-4.0
0.15-0.6
0.6-1.5
1.5-4.0
1.0-4.0
Unit flow
per foot of
strip width,
ft3/s
0.06-0.08
0.04-0.07
0.02-0.04
0.03-0.04
0.02-0.03
0.01-0.02
0.01-4.0
Avg depth
of water
applied, in.
2-4
2-4
2-4
4-6
4-6
4-6
1-3
Border
Width
15-60
15-20
15-20
15-60
15-20
15-20
15-20
strip, ft
Length
300-600
300-600
300
600-1 000
600-1 000
600
300-1 000
         1 ft3/s = 28.3 L/s
         1 in. = 2.54 cm
         1 ft = 0.305 m
each  strip,  and  is  preferably  located midway between the borders to
provide  uniform  distribution  across the strip (see Figure 5-11).   For
strips  having  widths  greater than 30 ft (9.1  m),  at least two outlets
per  strip  will ensure good distribution uniformity.  Use of gated  pipe
provides much more uniform distribution at the head  of border strips and
allows the flexibility of easily changing to ridge and furrow irrigation
if crop changes are desired.
          5.4.1.3  Rapid Infiltration Basins
The  design  of  rapid  infiltration  basins depends on topography;  when
subsurface  flow  is  to  a  surface water body,  the basin shape and the
elevation  difference  between  the  basins  and   the  surface water are
important.   The basins are usually formed by constructing earthen dikes
or by excavation.
Control of subsurface flow and recovery of renovated water are essential
considerations  for  proper  design of a rapid infiltration systems.  If
discharge  to  permanent  groundwater is not feasible, a recovery system
should  be  planned  to  withdraw  the  renovated water and reuse it for
irrigation  or recreation or discharge it to surface waters.  Methods of
recovery  include  underdrainage systems, pumped withdrawal, and natural
drainage to surface waters.
                                 5-48

-------
                              FIGURE  5-11

               OUTLET VALVE  FOR  BORDER  STRIP APPLICATION
Where  natural   subsurface  drainage  to   surface  water  is  planned, the
groundwater  table  must  be controlled  to prevent groundwater mounding.
The  aquifer should be able to readily transmit  the  renovated water away
from the infiltration site.  Bouwer [52]  suggests the  following equation
for  determining  the  required  elevation  difference between the water
course and the spreading basin.
                               WI = KDh/L
5-b)
where W = width of infiltration area,  ft (m)
      I = hydraulic loading rate, ft/a (m/d)
      K = permeability of aquifer, ft/d (m/d)
      D = average  thickness  of aquifer below water  table  perpendicular
          to flow direction, ft (m)
      H = elevation difference between water  level  in stream  or  lake  and
          maximum  allowable  water table level  below infiltration  area,
          ft (m)
      L = distance of lateral  flow,  ft (m)
The relationships of these parameters are indicated in Figure  5-12.   The
product  WI  defines the amount of the applied water for a  given  section
and thereby controls the infiltration basin sizing.  Thus,  if  the amount
of applied water is controlled by groundwater considerations,  relatively
                                  5-49

-------
large   hydraulic  loading  rates   (I)   may   be   employed   by   utilizing
relatively narrow (W)  basins.
                               FIGURE  5-12

                   NATURAL DRAINAGE  OF RENOVATED  WATER
                         INTO SURFACE  WATER  [52]
                                                 IMPERMEABLE
                                                   LAYER
Basin  sizing  includes  consideration   of   the   amount  of   usable  land
available,  the  hydraulic  loading   rate,   topography,   and  management
flexibility.   Sizing  may  also  be  influenced by groundwater considera-
tions as  discussed  in  the  previous  paragraph.  In  order to  operate a
system  on a continuous basis, at least two  basins will  be required, one
for  flooding and one for drying, unless sufficient storage is  available
elsewhere  in  the  system.    Multiple   basins   are desirable to  provide
flexibility in the management of  the system.
Basins  should  be  relatively  flat  to   allow   uniform  distribution of
applied  water  over  the  surface.   Thus, where  sloping  lands  are  to be
utilized,   terraced   basins   may   be    required.    Cross   slopes and
longitudinal   slopes  should  be  on  the  order of those  used for border
irrigation.   Basin  widths and lengths are  controlled by slopes, number
of basins desired for management,  distribution system  hydraulics, and as
previously discussed, water table  restrictions.
The  type  of  basin surface has been  the  subject of  considerable  debate
and  the  relative  advantages  and  disadvantages should  be  weighed  on  a
case-by-case  basis.  The surface may  consist  of  bare soil,  or  it  may be
covered  with  vegetation.  The advantages of  a vegetative cover include
                                   5-50

-------
maintenance  of  infiltration  rates,   removal   of  suspended   solids by
filtration,  additional  nutrient removal  if the vegetation  is  harvested,
and  possible promotion of denitrification.  Among the disadvantages are
increased  basin  maintenance,  lower  depth  of  application   to   avoid
drowning  the  vegetation,  and shorter periods of inundation  to promote
growth.  At Flushing Meadows, it was found that a gravel  covered surface
reduced  the infiltration capacity of a basin [53].   This was  attributed
to  the mulching effect of the gravel, which prevented the  drying  of the
underlying soil.
The distribution system for infiltration basins is often  similar  to  that
tor surface irrigation, although sprinklers have been  used.   The  purpose
of  the  distribution  system  is  to  apply  water at a  rate which  will
constantly  flood  the  basin  throughout  the  application   period  at  a
relatively  uniform  depth.   Effluent weirs may be used  to  regulate the
depth  of  applied water.  The discharge from the weirs is collected and
distributed to holding ponds for recirculation, or to  other  infiltration
basins.  Water may be conveyed to the basins by pipeline  or  open  channel
systems.   If  equal   flow  distribution is intended for  each basin, the
distribution  line  or  channel  supplying the outlets  to  parallel  basins
should  be  sized  so  that hydraulic losses between the  outlets  will be
insignificant.   Outlets  may  be  turnout  gates  from open channels or
valved  risers  from  underground  piping  systems.   A basin outlet and
splash pad are shown in Figure 5-13.
                              FIGURE 5-13

              RAPID INFILTRATION BASIN INFLUENT STRUCTURE
                                  5-51

-------
          5.4.1.4  Overland Flow
Overland  flow  distribution  is  accomplished  by  applying   wastewater
uniformly   over   relatively  impermeable  sloped  surfaces   which   are
vegetated.   Although  the  most  common  method of distribution  is  with
sprinklers,  surface  methods such as gated pipe or bubbling  orifice may
be  used  (Section  7.1.1).  Gravel  may oe necessary to dissipate energy
and ensure uniform distribution of water from these surface methods.
Slopes  must  be steep enough to prevent ponding of the runoff,  yet im'ld
enough  to prevent erosion and provide sufficient detention time for the
wastewater  on  the  slopes.   Experience at Paris, Texas,  has  indicated
that  best  results  are  obtained with slopes oetween 2 and 6%  [54].   A
slope  of  o«,  used  at  Utica,  Mississippi,  is shown in Figure  5-14.
Slopes  must  have  a  uniform  cross  slope and be free from gullies  to
prevent channeling and allow uniform distrioution over the  surface.  The
network  of slopes and terraces that make up an overland flow system may
be  adapted  to  natural  rolling terrain, as has been done at  Napoleon,
Ohio [11].   The  use  of  this  type  of  terrain  will minimize   land
preparation costs.
                              FIGURE 5-14
            OVERLAND FLOU SLOPE (8%)  AT UTICA,  MISSISSIPPI

                                   5-52

-------
          5.4.1.5  Distribution System Design

    r      ••'-.'.
Water  is, normally  conveyed  to surface distribution systems by canals
(lined and unlihed) or pipelines whose design standards are published  by
the American Society of Agricultural  Engineers (ASAE).  Design standards
for  flow, control  and  measurement techniques are also included in the
ASAE standards.
The  methods of flow,distribution to the fields include turnouts,  siphon
pipes',;•• valved  risers,  gated  surface  pipe,  and  bubbling  orifices.
Turhbuts  are;  circular  or  rectangular  openings  which discharge  flow
directly  from open ditches, canals, or open concrete pipe risers.   Flow
is  control led  by  slide  gates,  and discharge capacities are normally
restricted to velocities of 3 ft/s (1 m/s) or less.
Siphon  pipes are steel, aluminum, or plastic tubes (shown previously  in
Figure  5-9)  used  to  siphon water from open ditches to supply furrows
with  irrigation water.  Flow control is accomplished by combinations  of
pipe  sizes  or varying the number of pipes used.  Although siphon pipes
often  require the least capital expenditure for distribution,  operating
demands.,  are  significant  due  to  the  amount  of  handling   and the
requiremerit  for maintaining minimum water levels in the supply ditch  to
ensure continuity of flow.


Valved .risers  are,  vertical  concrete  pipe  risers attached  to buried
concrete  pipelines,  and  are  used  for  surface flooding irrigation  or
discharge to gated, pipe hydrants;   Flow is controlled by a simple wafer-
shaped  valve, which  is  adjusted  by a threaded stem.  The more common
valves  are, the  alfalfa  valve  (mounted  on top of the riser) and the
orchard  valve  (mounted inside the riser).  Typical   cross-sections and
capacities of these valves are shown in Figures 5-15 and 5-16.


Gated  surface pipe, which is attached to aluminum hydrants, is aluminum
pipe  with multiple outlets.  The pipe and hydrants are portable so that
they  may  be  moved for each irrigation.  As described in the  preceding
paragraph, the hydrants are mounted on valved risers.  Operating handles
extend  through  the  hydrants  to control the alfalfa or orchard valves
located in the risers.  Control of flow is accomplished with slide gates
or  screw adjustable orifices at each outlet.  The outlets are  spaced  to
match furrow spacings ano are usually fabricated to order.  Gated outlet
capacities  vary  with  the  available head at the gate, the velocity  of
flow passing the gate, and the gate opening.  Typical gate capacities  of
standard gated pipe for various flow velocities are shown in Table 5-25.
Hydrant  spacings  (and  valved riser spacings) are controlled  either  by
the  losses  in the gated pipe or by widths of boraer strips when border
and .furrow methods are alternated.
                                 5-53

-------
               FIGURE  5-15

   ALFALFA VALVE  CHARACTERISTICS
                                               CONCRETE RISER
                                               FROM LATERAL
            CROSS SECTIONAL VIEW
                                              1   i n. = 2.54 cm
SIZES  AND RECOMMENDED MAXIMUM DESIGN CAPACITIES
Inside
diameter
of riser,
in.
6
8
10
12
14
16
18
20
Diameter
of port,
in.
6
8
10
12
14
16
18
20
Maximum design capacity
Usual
low head,
ft3/sa
0.8
1.4
2.2
3.1
4.3
5.6
7.1
8.7
High head,
ft3/sb
1.6
2.8
4.4
6.3
8.6
11.2
14.2
17.5
 a.   Recommended for minimum erosion with
     hydraulic gradient  1 ft above ground.
     Assumed 0.5 ft ponding over valve.

 b.   Can  be used where higher pressures
     are  available (hydraulic gradient
     2.5  ft above ground) and pre-
     cautions are taken  to prevent
     erosion (ponding =0.5 ft).

 1  in.  =  2.54 cm
 1  ft3/s  = 0.284 m3/s
 1  ft = 0.305 m
                   5-54

-------
                                  FIGURE 5-16

                   ORCHARD  VALVE  CHARACTERISTICS  [55]
                                         AT GROUND SURFACE-
CONCRETE RISER
FROM LATERAL
                               CROSS SECTIONAL  VIEW
                                                                 1  ft = 0.305  m
                        SIZES AND RECOMMENDED MAXIMUM CAPACITIES
Inside diameter
of riser, in.
6
6
6
6
8
8
10
10
10
12
12
Diameter of
valve outlet, in.
1.5
2.5
3.5
6
5
8
6
6.5
10
8
12
Approximate design
capacities, ft3/s
Low head3
0.04
0.12
0.23
0.67
0.46
1.18
0.67
0.78
1.85
1.18
2.67
Higher headb
0.08
0.23
0.45
1.34
0.93
2.37
1.34
1.57
3.71
2.37
5.35
               a.  Usual  design with  hydraulic  gradient 1  ft above ground.

               b.  Higher head design with hydraulic gradient 2.5 ft
                  above  ground.

               1 in. = 2.54 cm
               1 ft3/s =  0.0284 m3/s
               1 ft = 0.305 m
                                    5-55

-------
                               TABLE 5-25

         DISCHARGE CAPACITIES OF SURFACE GATED PIPE OUTLETS [56]
                           Gallons per Minute
Velocity
in pipe,
ft/s
0




1




3





Head,
ft
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5

Gate opening
Full
48.
67.
80.
87.
94.
45.
63.
76.
84.
90.
40.
56.
69.
76.
83.

8
2
1
7
2
3
7
6
2
7
0
4
3
9
4

3/4
35.7
50.0
60.8
69.5
77.1
32.8
47.1
57.9
66.6
74.2
26.7
41.0
51.8
60.5
68.1

1/2
22
32
39
45
50
21
.8
.3
.1
.3
.6
.3
30.8
37
43
49
18
27
34
40
46

.6
.8
.1
.2
.7
.5
.7
.0

1/4
10.
15.
18.
21.
23.
10.
14.
17.
21.
23.
8.
13.
16.
19.
21.

6
3
3
4
7
2
9
9
0
3
8
5
5
6
9

1/8
5.
7.
8.
9.
10.
4.
6.
8.
9.
10.
4.
6.
7.
9.
10.

0
0
5
7
7
9
9
4
7
7
3
3
8
0
0

1/16
2.3
3.2
3.8
4.3
4.8
2.2
3.1
3.7
4.2
4.7
2.1
3.0
3.5
4.1
4.6
i
                 1 gal/min = 0.063 L/s
                 1 ft/s = 0.305 m/s
Bubbling  orifices  are  small  diameter  outlets  from laterals used to
introduce  flow  to  overland  flow  systems  or checks at'low operating
pressures.   Such  outlets  may  consist  of orifices in the laterals or
small  diameter  pipe stubs attached to the laterals.  Outlets may range
from O.b to 2 in. (1.3 to 5 cm) in diameter, the capacities of which are
regulated by the available head.        ,          •           ,.   '  :   "'
     5.4.2  Sprinkler Systems
Sprinklers  can  be  for  all types of land treatment systems.  The most
common   types   of   sprinklers  may  be  cat'egorized  as  hand  moved,
mechanically moved,, and permanent set.  The basic layout features of the
various types of systems are depicted in Figures 5^17,'5-18, and 5-19.
The   more   significant  design  considerations  for  sprinkler  system
selection  include  field conditions (shape, slope, vegetation, and soil
type), climate, operating conditions (system management) ;• and ecpnornics.
These considerations are summarized in Table 5-26.             '
                                5-56

-------
                FIGURE  5-17

      HAND  MOVED SPRINKLER SYSTEMS
PREVIOUSLY
IRRIGATED
  AREA
LATERAL  WITH MULTIPLE
    SPRINKLERS
                                    _ MAIN
PUMP
             (a)   PORTABLE  PIPE
PREVIOUSLY
IRRIGATED
  AREA
PUMP
     LATERAL  WITH SPRINKLER
          CONNECTIONS
                                       MAIN
                                        GUN-TYPE
                                        SPRINKLER
          (b)   STATIONARY  BIG GUN
                    5-57

-------
                                 FIGURE 5-18

                   MECHANICALLY MOVED SPRINKLER SYSTEMS
LATERAL WITH MULTIPLE
    SPRINKLERS
            PREVIOUSLY
            IRRIGATED
            AREA
                              DISASSEMBLED
                              MAIN LENGTHS
        ANCHOR
                                              SELF-PROPELLED
                                              DRIVE UNIT WITH
                                              GUN-TYPE  SPRINKLER
                                                MAIN
                                         PUMP
                        CABLE
           (a)   END TOW
(b)   BIG GUN  TRAVELER
                                                                         PREVIOUSLY
                                                                         -IRRIGATED
                                                                             AREA
      MAIN
                    WHEEL-SUPPORTED  LATERAL
                    WITH MULTIPLE SPRINKLER
                                  PREVIOUSLY
                                  IRRIGATED
                                  AREA
                                       POWER
                                       DRIVE
                                       UNITS
                            LATERAL
                             WITH
                           MULTIPLE
                           SPRINKLER
                          PREVIOUSLY
                          IRRIGATED
                            AREA
       (c)  SIDE WHEEL  ROLL
   (d)  CENTER PIVOT
                                        5-58

-------
                                   FIGURE 5-19

                    PERMANENT  SOLID  SET SPRINKLER  SYSTEM
             BURIED LATERALS
             WITH MULTIPLE
             SPRINKLER
                PUMP
                    f
                                                    — BURIED MAIN
                                                        PREVIOUSLY  IRRIGATED
                                                               AREA
                                    TABLE  5-26

                   SPRINKLER SYSTEM CHARACTERISTICS [57,  58]
Typical
application
rate, in./h
Hand moved
Portable pipe
Stationary gun
Mechanically
moved
End tow
Traveling gun
Side wheel roll
Center pivot
Permanent
Solid set


0.1-2.0
0.25-2

0.1-2.
0.25-1.
0.1-0-2.
0.20-1.

0.05-2.
.0

.0
.0
.0
.0

.0
Outlets
per lateral

Multiple
Single

Multiple
Single
Multiple
Multiple

Multiple
Nozzle
pressure
range,
lb/in.2

30-60
50-100

30-60
50-100
30-60
15-60

30-60
Size of
single
system,
acres

1-40
20-40

20-40
40-100
20-80
40-160

Unlimited
Shape of
field

Any shape
Any shape

Rectangular
Rectangular
Rectangular
Circular3

Any shape
Maximum
slope, %

20
20

5-10
Unlimited
5-10
5-15

Unlimited
Maximum
crop
height,
ft

....




3-4
8-10


 a.  Travelers are available to allow irrigation  of any  shape  field.

1 in./h = 2.54 cm/h
1 lb/in.2 = 0.69 N/cm2
1 acre = 0.405 ha
1 ft = 0.305 m
                                      5-59

-------
          5.4.2.1   Hand Moved Systems


Hand  moved  sprinkler  systems include  portable  pipe  and  stationary  gun
systems.   As  the name implies,  each  is placed and  removed  manually  for
each irrigation set or period.


Portable pipe  systems  are  surface   pipe  systems consisting  of  lateral
lines which are moved between sets  (piping  position  for one  application)
and  a  main  line which may also be moved,  or it may  be permanent.   The
laterals  are  usually constructed  of  aluminum pipe  in 30  or 40 ft  (9 or
12 in)  lengths  with  sprinklers  mounted  on  risers  extending from  the
laterals.   Riser  heights  are  determined by crop  heights  and angle of
spray.   In general, lateral spacings  and sprinkler  spacings are  located
at  approximately  equal intervals, usually ranging  from 40  to 90 ft  (12
to  27 m).   Sprinklers  may  operate  at  a wide range of pressures  and
application.   If  sufficient pipe  is  available so that movement  between
sets is not required, the system  is referred to as solid set.
The  major  advantages of portable systems  include  low capital  costs  and
adaptability  to  most  field conditions  and  climates.  They  may  also be
removed from the fields to avoid interferences with farm machinery.   The
principal   disadvantage   is  the extensive labor  requirement to  operate
the system.
Stationary  gun  systems  are   wheel-mounted    or  skid-mounted   single
sprinkler  units(seeFigure  5-20),   which  are  moved  manually  between
hydrants  located  along  the laterals.   Since the sprinkler  operates  at
greater  pressures  and  flowrates   than multiple  sprinkler systems, the
irrigation  time is usually shorter.  After  a  set  has  been completed for
the  lateral,  the  entire  lateral  is moved to the next point along the
main.  In some cases a number of laterals and  sprinklers may  be provided
to minimize movement of laterals.
The advantages of a stationary gun  are similar  to  those  of  portable  pipe
systems with respect to capital  costs  and  versatility.   In  addition,  the
larger  nozzle  of  the  gun-type   sprinkler  is   relatively   free   from
clogging.   The  drawbacks  to this system are  also  similar to those  for
portable  pipe  systems  in  that   labor  requirements   are  high due to
frequent sprinkler moves.  Power requirements are  relatively  high due to
high  pressures  at  the  nozzle,   and windy conditions  adversely affect
distribution of the fine droplets created  by the higher  pressures.


          5.4.2.2  Mechanically Moved  Systems


The  most  common  types  of  mechanically moved   systems  are end  tow,
traveling  gun, side wheel roll, and center pivot.  These  systems may be
                                5-60

-------
moved  after  each  irrigation by external  drive mechanisms (tractors  or
winches)  or  integral  drive  units,  or  they  may  be self-propelled,
continuous-moving systems.
                              FIGURE 5-20

         STATIONARY GUN SPRINKLER MOUNTED ON A TRACTOR TRAILER
End  tow  systems  are  multiple-sprinkler  laterals mounted on skids or
wheel  assemblies to allow a tractor to pull the lateral intact from one
setting to the next.  As indicated in Figure b-18, the lateral  is guided
by  capstans  to  control  its alignment.  The pipe and sprinkler design
considerations are identical to those for portable pipe systems with the
exception  that  pipe  joints  are  stronger  to accommodate the pulling
requirements.
The  primary  advantages  of  an end tow system are relatively low labor
requirements  and overall system costs, and the capability to be readily
removed   from   the   field  to  allow  farm  implements  to   operate.
Disadvantages  include  crop  restrictions  to  movement of laterals and
cautious operation to avoid crop and equipment damage.
Traveling  gun systems are  self-propelled, single sprinkler units which
are connected to the supply source by a flexible hose (see Figure 5-21).
The   traveler  is  driven  by  a  hydraulic or  gas-driven winch located
within  the  unit, or a  gas-driven winch located at the end of the run.
In both cases, a cable anchored at the end of the run guides the unit in
                                  5-61

-------
a  straight path.  Variable speed drives  are  used  to  control  application
rates.   Typical   lengths of run are 660  or 1  320  ft  (201  or  403 in), ana
spacings  between  travel  lanes are commonly  33U ft  (100 in).   The  rubber
hose,  which  may  be  2.5 to  b in.  (6.4 to  12.7  cm)  is a specially-
constructed item  and may constitute a considerable  portion of the  total
cost of the system.
                              FIGURE 5-21

                        TRAVELING GUN SPRINKLER
The  more  important  advantages of a traveling gun  system are low  labor
requirements  and  relatively  clog-free  nozzles.    They  may  also   be
adapted   to   fields  of  somewhat  irregular  shape  and   topography.
Disadvantages are high initial  costs and power requirements,  hose  travel
lanes  required  for  most  crops,  and  drifting  of  sprays  in   windy
conditions.
Side  wheel  roll  systems  consist of aluminum or galvanized steel  pipe
laterals  4 to  5 in.  (10.2 to 12.7 cm)  in diameter,  which act as  axles
for 5 to 7 ft (1.5 to 2.1 m) diameter wheels (see Figure 5-22).  The end
of  the  lateral, which is typically 1 320 ft (403 m)  long, is connected
to  hydrants  located  along the main line.  The system is moved between
sets  by  an  integral  drive unit located at the center of the lateral.
The  unit  is  a  gas-driven  engine  operated  by  the  irrigator.   The
sprinklers,  which  have  the  same general characteristics as those for
                                  5-62

-------
portable  pipe  systems,  are  mounted  on  swivel  connections  to  ensure
upright  positions at all  times.   Sprinkler spacings are typically 3D  or
40 ft  (9.2 to  12.b m)   ana  wheel  spacings may range  from  30  to  10U  ft
(9.2 to  30.b m).    Side wheel  laterals may be equipped with trail  lines
up to 90 ft (27 in) in length located at each sprinkler  connection  on the
axle  lateral.   Each trail  line  has sprinklers mounted on  risers  spaced
typically at 30 to 40 ft (9  to 12 m).   Use of trail  lines allows  several
lateral  settings   to be irrigatea simultaneously and reduces the  number
of moves required  to irrigate a field.
                              FIGURE b-22

                   SIDE WHEEL ROLL SPRINKLER SYSTEM

                                                   *>4

The  principal  advantages of side wheel  roll  systems are relatively low
labor requirements and overall costs, and freedom from interference with
farm  implements.  Disadvantages include  restrictions to crop height and
field shape, and misalignment of the lateral  caused by uneven terrain.
A  center  pivot  system  is a lateral  with multiple sprinklers which  is
mounted  on  self-propelled, continuously moving tower units (see Figure
b-23) rotating about a fixed pivot in the center of the field.   Water  is
supplied  Dy  a  well or a buried main to the pivot, where power is also
furnished.    The  lateral  is usually constructed of 6 to 8 in.  (15 to  20
cm)  steel   pipe  200 to 2 600 ft  (61  to  793 m) in length.   A  typical
system  irrigates  a  160 acre  (64 ha)  parcel   (see Figure 5-24)  with
a  1  288  ft  (393 m) lateral.  The circular pattern reduces coverage  to
about  130 acres (52 ha), although systems with traveling end sprinklers
are available to irrigate the corners.
                                   5-63

-------
          FIGURE b-23




       CENTER PIVOT RIG
          FIGURE 5-24




CENTER PIVOT IRRIGATION SYSTEM

                                      _.
              5-64

-------
The  tower  units  are  driven  electrically or hydraulically  and may be
spaced  from  80 to 250 ft (24 to 76 m)  apart.   The  lateral  is supported
between  the  towers  by  cables or trusses.  Control  of the application
rate  is  achieved  by  varying  the  running  time  of the  tower motors.
Variations  in  sprinkler  sizes  or spacings must be  provided along the
lateral  for  uniform  distribution,  since  the  area  of   coverage per
sprinkler  increases  with the distance  from the center. The  relatively
low  application  rates  shown  in  Table 5-26 account for  the fact that
center  pivot  systems  irrigate more frequently and at lower  rates than
other systems.
Another  type  of center pivot system is the rotating boom.   This  system
eliminates  the  need  for  wheel-mounted  power units by supporting  the
lateral  with cables extending from a tower at the pivot.  These  systems
have  limited  applications,  as the area of coverage is small, up to 40
acres  (16  ha),  relative to conventional  center pivot systems,  and  the
corresponding  per  acre  costs  are  high  when  multiple  systems  are
required.
The  main  advantage  of  a  center  pivot  system is the high degree  of
automation  and  a corresponding low requirement for labor.   Limitations
include  restricted area of coverage (dead spaces in corners of fields),
crop heights, and potential maintenance problems related to  the numerous
mechanical components.
          5.4.2.3  Permanent Solid Set Systems
Permanent  solid  set  systems are distinguished from portable solid  set
systems  only in that the laterals are buried and constructed of plastic
pipe  instead of aluminum.  Sprinkler selection and spacing criteria  are
identical.   Risers  may  be  fixed  or  removable  to  accommodate  farm
equipment.   The  primary  advantages of solid set systems are low labor
requirements  and  maintenance  costs,  and adaptability to all  types of
terrain,  field  shapes,  and  crops.   They are also the most adaptable
systems  for  climate control requirements.  The major disadvantages  are
high  installation  costs  and  obstruction  of  fixed risers to farming
equipment.
          5.4.2.4  Overland Flow Systems
Sprinkler  application  for  overland  flow consists either of permanent
solid  set  systems  or rotating booms.  These systems are distinguished
from  those  for  slow  rate by their layout arrangements (single row of
sprinklers)  and  application  rates  (designed  for runoff).  Sprinkler
                                    5-65

-------
spacing  is  normally  equal   to  the  radius of the wetted circle,
sprinkler discharge rate,  Q ,  may be computed as follows:
                                    The
                             Q =
I  x R x L
  t x C
(5-7)
where Q = nozzle discharge, gal/min (L/s)
      I = total depth of water applied, in.
      t = period of time to apply water, h
      R = spacing between sprinklers, ft (rn)
      L = length of overland slope, ft (m)
      C - constant = 96.3 (360)
           (cm)
Sprinkler  heads  may  be  arranged  to  avoid drifting of sprays at the
expense  of reducing the area of coverage.  The primary objective of the
distribution  system  is  to  concentrate the applied water at the upper
ends of the slopes to produce runoff.
Fan  nozzles  may  be  used  for  overland flow distribution to minimize
pumping  pressure head and minimize aerosol  formation.  At Pauls Valley,
Oklahoma  (Section  7.11),  fixed  nozzles  are  being  used.   At  Ada,
Oklahoma, rotating booms are being used with fan nozzles on both ends as
shown in Figure 5-25.
                              FIGURE 5-25

                     ROTATING BOOM, FAN SPRINKLER,
                            ADA, OKLAHOMA

                                    5-66

-------
          5.4.2.5  System Design


The  procedure for sprinkler system design involves the determination of
the optimum rate of application, sprinkler selection, sprinkler spacings
and  performance  characteristics,  lateral  design,  and  miscellaneous
requirements.    Although  the  following  discussions  are  limited  to
stationary  systems,  the  general  theory  applies to moving systems as
well.  Detailed design requirements for specific systems may be obtained
from equipment suppliers.


The  optimum rate of application for a sprinkler system is the rate that
ensures   uniform  distribution  under  prevailing  climatic  conditions
without exceeding the basic intake rate of the soil (except for overland
flow systems).


Sprinkler selection is primarily based on conditions of service, such as
type  of  distribution  system,  pressure limitations, application rate,
clogging   potential,  and  effects  of   winds.   Sprinklers  used  for
application of wastewater are usually of the rotating head type with one
or  two  nozzles.  Special attention should be given to sprinkler design
for  low  temperature  winter  operation.   A  general classification of
sprinklers  and  their  adaptabilities  to various service conditions is
presented  in Table 5-27.  More specific performance characteristics for
the   many   types  of  sprinklers  are  available  from  the  sprinkler
manufacturers.
Sprinkler  spacings and performance characteristics are jointly analyzed
to  determine  the most uniform distribution pattern at the optimum rate
of  application.   Distribution  patterns  of  individual  sprinklers are
affected  primarily  by  pressure—low pressures cause large drops which
are  concentrated  in a ring a certain distance away from the sprinkler,
whereas  high  pressures  result  in  fine  drops  which  fall   near the
sprinkler.  These finer sprays are easily distorted by winds.
Since  the  amount  of  water  applied by a sprinkler decreases with the
distance  from  the  nozzle  and  the  distribution pattern is circular,
sprinklers  and laterals are spaced to provide overlapping of the wetted
diameters.   Spacings  are  normally  related  to  the  wetted diameters
specified  by  the  sprinkler  manufacturers.   These  spacings  may  be
determined  empirically  or  by  using  published  guidelines.   The SCS
recommends  limiting  sprinkler spacinys along the lateral  (S[_)  to 50%
or  less  of  the  wetted  diameter, and lateral  spacings along the main
(S^)  to  less  than 65%.  In windy areas,  S^  should be reduced to 50%
for  velocities  of  5  to  10  mi/h  (2.2  to  4.4  m/s) and to 30% for
velocities  greater  than  10  mi/h  (4.4  m/s) [59].  For high pressure
sprinklers,  the  SCS  recommends  a  maximum  diagonal  distance between
sprinklers of two-thirds the wetted diameter with similar deductions for
wind as discussed for lower pressure sprinklers.
                                   5-67

-------
                                                  TABLE  5-27

                                  CLASSIFICATION  OF SPRINKLERS  AND
                                         THEIR  ADAPTABILITY  [58]
Type of
sprinkler
Low pressure,
5-15 lb/in.2


Moderate
pressure,
15-30 lb/in.2

Intermediate
pressure,
30-60 lb/in. z

High pressure.
50-100 lb/in. 2

General
characteristics
Special thrust
springs or reaction-
type arms

Usually single-nozzle
oscillating or long-
arm dual-nozzle
design
Either single or
dual-nozzle design


Either single of
dual-nozzle design

Range of
wetted
diameters,
'ft
20-50



60-80



75-120



110-230


Recommended
minimum
application
rate, in./h
0.40



0.20



0.25



0.50


Moisture
distribution
pattern3
Fair



Fair to "good at
upper limits of
pressure range

Very good



Good except
where wind
velocities ex-
Adaptations and limitations
Small acreages; confined to soils
with intake rates exceeding 0.50 in./h
and to good ground cover on medium-
to coarse-textured soils
Primarily for undertree sprinkling
in orchards; can be used for field
crops and vegetables

For all field crops and most irrigable
soils; well -adapted to overtree
sprinkling in orchards and groves and
to tobacco shades
Same as for intermediate pressure
sprinklers except where wind is
excessive
Hydraulic  or      One large nozzle with   200-400        0.65
giant,  80-        smaller supplemental
120 lb/in.2       nozzles to fill in
                 pattern gaps; small
                 nozzle rotating
                 sprinkler

Undertree  low-    Designed to keep         40-90        0.33
angle,  10-        stream trajectories
50 lb/in.2'       below fruit and
                 foliage by lowering
                 the nozzle angle
Perforated  pipe,  Portable irrigation      lO-Sff5        0.50
4-20 lb/in.2      pipe with lines of
                 small perforations
                 in upper third of
                 pipe perimeter
Acceptable  in    Adaptable to close-growing crops that
calm air;        provide good ground cover; for rapid
severely dis-    coverage and for odd shaped areas;
torted by wind   limited to soils with high intake rates
Fairly good;      For all orchards  or citrus groves; in
diamond pattern   orchards where wind will  distort over-
recommended       tree sprinkler patterns;  .in orchards
where laterals    were available pressure is not suffi-
spaced more       cient for operation of overtree
than one tree     sprinklers
interspace

Good pattern is   For low growing crops only; unsuitable
rectangular       for tall crops; limited to soils with
                 relatively high intake rates; best
                 adapted to small  acreages of high value
                 crops; low oeprating pressure permits
                 use of gravity or municipal supply
a.   Assuming proper spacing  and pressure nozzle  size relationships.

b.   Rectangular strips.

1 ft =  0.305 m
1 in. = 2.54 cm
1 lb/in.2 = 0.69 N/cm2
1 mi/h  = 0.44 m/s
                                                       5-68

-------
Once  the  preliminary spacing has been determined,  the  nozzle  discharge
capacity to supply the optimum application rate is found by  the equation
                               Q =
                                   SL x SM x
                                                    (5-8)
in which  Q  =  flow rate from nozzle,  gal/min  (L/s)
         SL  =  sprinkler spacing along lateral,  ft (m)
         SM  =  sprinkler spacing along main,  ft  (m)
          I  =  optimum application rate,  in./h (cm/h)
          C  =  constant = 96.3 (360)
This  establishes  the  basis  for final  sprinkler selection,  which  is a
trial   and   adjustment   procedure  to   match  given  conditions   with
performance   characteristics  of  available   sprinklers.   The  normal
selection  procedure
discharge  capacity.
the   nozzle   sizes,
sprinklers  operating
diameters  are  then
with the established
             is  to  a-ssume  a  spacing  and  determine  the nozzle
             Manufacturers'  data  are  then reviewed  to determine
              operating   pressures,   and  wetted  diameters  of
              at  the desired  discharge    rate.   The  wetted
             checked  with the  assumed  spacings for conformance
            spacing criteria.
Lateral  design consists of selecting lateral  sizes to deliver the  total
flow  requirement  of  the  lateral   with  friction  losses limited to  a
predetermined  amount.   A  general   practice   is to limit all  hydraulic
losses  (static  and  dynamic)  in  a  lateral   to  2U% of the operating
pressure  of  the  sprinklers.   This will  result in sprinkler discharge
variations  of  about  10%  along the lateral  [58].  Since flow is  being
discharged  from  a number of sprinklers, the  effect of multiple outlets
on  friction  loss  in  the  lateral   must  be considered.  A simplified
approach  developed  by Christiansen is to multiply the friction loss  in
the  entire  lateral  at  full  flow  (discharge at the distal  end)  by  a
factor based on the number of outlets.  The factors for selected numbers
of outlets are presented in Table 5-28.  For long lateral  lines, capital
costs  may  be  reduced  by  using  two or more lateral sizes which will
satisfy the head loss requirements.
System
automation  is  receiving  greater  attention  as   labor  costs
   All   of  the  systems  described  herein may  be  automatically
   to  some degree.   The most common control  devices  are  remote
increase.
controlled
control  valves energized electrically or pneumatically to start or stop
flow in a lateral or main.  The energy source for operating these valves
may be activated manually at a push-button station or automatically by  a
time-controlled  switch.   In  order  to  determine  the  economics of  a
control  system,  the  designer must compare the costs of labor with the
costs of controls at the desired level of operating flexibility.
                                  5-69

-------
                               TABLE 5-28

                 FACTOR  (F) BY WHICH PIPE FRICTION LOSS
                 IS MULTIPLIED TO OBTAIN ACTUAL LOSS IN
                    A LINE WITH MULTIPLE OUTLETS [49]
                          No. of outlets  Value of F
1
2
3
4
5
6
7
8
9
10
15
20
25
30
40
50
100
1.000
0.634
0.528
0.480
0.451
0.433
0.419
0.410
0.402
0.396
0.379
0.370
0.365
0.362
0.357
0.355
0.350
5.5  Management of Renovated Water


     5.5.1  General Considerations


          5.5.1.1  Flow to Groundwaters
For  rapid  infiltration,  an  unsaturated  soil  zone  is  necessary to
maintain  desired  infiltration  rates  since oxygen is usually depleted
when  inundation  periods  exceed  48  hours.   However,  good  internal
drainage must be present to reinstate an aerobic zone during the  dry-up
period.   Bouwer reports that only 5 ft (1.5 m) of unsaturated soil need
be  maintained  [52].  A deeper water table does not materially increase
the  depth  of  the  aerobic  zone  since  oxygen  diffusion  is  slowed
considerably below about 3 ft (1 m).
                                  5-70

-------
          5.5.1.2  Stormwater Runoff Considerations
The  quality  of  stonnwater  runoff  is  essentially  unknown,  but the
nitrogen  and  phosphorus  values given in Table 3-11, measured in rural
stonnwater  runoff  studies, should give perspective to the magnitude of
the  problem.  The principal considerations are to minimize the quantity
of  runoff and to minimize the sediment load in the runoff.  This can be
accomplished for the most part by sound farm management practices.
Overland  flow systems are designed to shed water and must be capable of
handling  storm  runoff  flows.  It has been shown at Paris, Texas [54],
that  the  effect of precipitation is to improve the quality of overland
flow runoff as measured by electrical conductivity.
     5.5.2  Underdrainage Systems


Underdrains  are mainly associated with slow rate treatment but can also
be  used  with  rapid  infiltration treatment.  The underdrainage system
must  control  the water table to provide sufficient soil  detention time
and  underground  travel   distance  if  the desired quality of renovated
water  is  to  be  achieved.   In  the  case of slow rate treatment, the
ability  to plant, grow,  and harvest a crop properly also depends on the
drainage  conditions.   Skaggs  has developed a model  to manage water in
soils with high groundwater [60, 61].


In  arid  regions,  drains are usually placed at much greater depths and
farther  apart  than  in  humid  regions to ensure that salt-laden water
cannot move upward to the root zone by capillary action.  Since there is
no real agreement on proper depth and spacing, the designer is forced to
rely  on local  experience.  Examples of drain depth and spacing in humid
and arid climates, for slow rate systems, are shown in Table 5-29.
Control  of  the  groundwater  table is discussed in Appendix C,  Section
C.4.   An  equation  for  spacing  and  depth  underdrains is presented.
Additional   discussion  of  the  theoretical  aspects of drain spacing is
contained  in  references  [60,  61,  62].    Procedures for planning and
design  of  underdrainage  systems  are  also  described  in Drainage of
Agricultural    Land   by   the  U.S.  Department  of  Agriculture,   Soil
Conservation Service [63].
                                  5-71

-------
                               TABLE  5-29

        DEPTH  AND SPACING OF UNDERDRAINS  FOR SLOW RATE SYSTEMS
                                  Feet
                                            Avg depth   Spacing

               Arid climate
                 Imperial Valley, California [62]    6-9      200-400
                 Delta, Utah [62]                ...a     1 000-1 320
               Humid climate
                 Malheur Valley, Oregon [62]       8-9        660
                 Muskegon, Michigan, loamy to
                 sandy soils [31]                5-8      500-1 000
               Skaggs Water Management Model
                 Sandy loam [60]                 3.2        265
                 Sandy loam [61]                 3.3        140
                 Clay loam [61]                 3.3       40-65b

               a. Referred to as deep drains.
               b. Good surface drainage increases spacing.

               1 ft  = 0.305 m


Proper  placement  of   underdrains to recover renovated  water from rapid
infiltration   treatment  is  more critical  than for slow rate treatment.
Bouwer [52]    has  developed  an  equation  to  determine   the  distance
underdrains   should  be  placed   away  from  the infiltration area.  The
height, H   ,  of  the water table below the  outer edge  of  the infiltration
area (see  Figure 5-26) can be calculated:


                         Hc2 = Hd2 +  IW (W  + 2D/K        (5-9)

where Hd = drain height above impermeable  layer, ft  (m)
       I = infiltration rate, in./h  (cm/h)
       W = width of infiltration  basin, ft (m)
       L = distance to underdrain, ft (m)
       K = permeability of the soil, in./h (cm/h)


The location  of the drain  is selected and  HC  is calculated with Equation
5-9.  By adjusting variables (L,  W,  and I), a satisfactory value  of   Hc
is obtained.   An L-value less than the most desirable distance of under-
ground travel may have to  be accepted to obtain a  workable system.


Plastic,   concrete,   and  clay tile  lines  are used for  underdrains.  The
choice  usually   depends  on price and availability of materials.   Where
sul fates   are  present  in  the   groundwater,  it  is necessary to use a
sul fate-resistant  cement pipe, if concrete is chosen,  to  prevent excess
                                    5-72

-------
internal   stress   from  crystal   formation.   Most  tile  drains   are
mechanically laid in a machine dug trench (see Figure 5-27) or by direct
plowing.  In organic soils and loam and clay-loam soils,  a filter is  not
needed.  The value of a filter is also dependent on the cost of cleaning
a plugged tile line versus the cost of the filter material.
                              FIGURE 5-26

              COLLECTION OF RENOVATED WATER BY DRAIN [52]
                                         WATER TABLE
                       ^	 IMPERMEABLE LAYER
     5.5.3  Pumped Withdrawal
Pumped  withdrawal  of percolated water is generally only considered for
rapid  infiltration  systems.   It can be the economical recovery method
when  the  aquifer is deep enough (more than 15 ft or 4.5 m usually) and
permeable enough to allow pumping.  Evaluation of the permeability of an
aquifer  to properly locate recovery wells is based on the principles of
groundwater flow presented in Appendix C.


Procedures  for  obtaining the necessary information on the permeability
for  rapid infiltration systems have been developed by Bouwer [64].  Two
procedures,   (1) an   analog   technique  and   (2) field  permeability
measurements,  predict  water  table positions for a system of parallel,
rectangular  infiltration  basins, with wells located midway between the
basins as shown in Figure 5-28.  The shape of the water table system can
be   calculated   with  dimensionless  graphs  developed  with  Bouwer's
electrical  analog technique [64] and summarized in reference [52].  The
evaluation ,of  the  permeability  components  by  the  analog technique
requires a knowledge of the infiltration rates and the response of water
levels  in  the  recovery  (or  observation)  wells  at different depths
located between the basins.
                                   5-73

-------
                              FIGURE 5-27

                  TRENCHING MACHINE FOR INSTALLATION
                             OF DRAIN TILE
     5.5.4  Tailwater Return
It  is standard design practice to include a tailwater return system for
wastewater  runoff from excess surface application in slow rate systems.
Typically, tailwater systems consist of a small  pond, a pump, and return
pipeline.   The  system  is  usually  sized for 25 to 50% of the applied
surficial  flow.   Suggested  guidelines,  recommended  by the ASAE, for
determining  runoff  as  a  percentage of the application rate have been
summarized by Hart [56] and are included here.
                                   5-74

-------
                                 FIGURE 5-28

             PLAN AND CROSS  SECTION OF TWO  PARALLEL RECHARGE
              BASINS WITH WELLS MIDWAY BETWEEN BASINS [64]
                             RECHARGE BASINS
                                       RECOVERY
                                         WELL
                                  PLAN
























J








1





1





1





1



























•X'!





**r





*+*
















J








I





1


j


1





/<


/— »


A


T


ER TABLE


  N N N \ X \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ V\
                              CROSS  SECTION
Total  application   time should be  long enough to  properly wet the  lower
end  of   a   field.   The  time that applied wastewater is allowed  to  enter
the  tailwater runoff  system before the supply source is cut off and the
runoff volume depend on  the intake  rate of the soil.   For slow rate land
treatment,   the  practical   guidelines   shown  in  Table 5-30 provide the
simplest  procedure for estimating runoff factors.

                                 TABLE 5-30
                  RECOMMENDED ASAE  RUNOFF DESIGN FACTORS
                    FOR SURFACE  FLOOD DISTRIBUTION [56]
          Pnrmcnhil1ty                     Maximum runoff   Estimated runoff
      	              duration, % of     volume, % of
       Class       Rate,  in./h  Texture range  application time  application volume
      Slow to
      moderate

      Moderate to
      moderately
      rapid
0.06 to 0.6 Clay to silt       33


 0.6 to 6.0 Clay loams to      75
          sandy loams
15


35
      1 in./h  =2.54 cm/h
                                    5-75

-------
The  rate  of  runoff  increases with  time  and  tends  to  reach a constant
value  as cutoff time is approached.   A  runoff  duration  of  one-half  the
application  time  and  a  maximum runoff rate  of  two-thirds application
rate  results  in a runoff volume of about  25%  of  application for  slowly
permeable  soils [56].   Permeable soils, with  intake rates greater than
0.8  in./h  (2 cm/h), require rapid advance rates  and shorter irrigation
times  if  deep  percolation is to be  minimized.   If  deep percolation is
not a problem, longer application periods can be used.
Design  factors  on  sumps, pumps,  and  storage  reservoirs  for continuous
pumping  systems  and  cycling sump systems  are beyond  the scope  of  this
manual but can be obtained from references [56, 65].
     5.5.5  Overland Flow Runoff
Runoff  will  range  from  40 to 80% of the  applied  liquid  depending  on:
(1)  soil  infiltration  capacity,   (2) prior  moisture  condition  of  the
soil,  (3) slope,  and (4) type of  vegetation.   Percent  runoff will vary
over  the  year  depending  on  the  rainfall  and evaporation.  A water
balance should be performed to estimate the  runoff volume.
At the Campbell Soup overland flow system  in  Paris,  Texas,  Thomas et  al.
determined  that direct evaporation from sprinklers  ranged  from  2 to  8%;
evapotranspiration   ranged   from  7   to   27%   of   the   applied liquid
(wastewater  ana  rainfall);  while runoff  ranged from  a midsummer low of
42%  to  a  high  of  71%  in  midwinter   [66].   Similar  studies at Ada,
Oklahoma,  indicated  that overall recovery was  about  50% of  the applied
wastewater, and ranged from 25% in summer  to  80% in  winter  [17].
Runoff collection systems are commonly open,  grass-lined  channels  at  the
toe of the overland flow slopes.   They must be  graded  to  prevent erosion
(typically  0.3  to  1%) and have sufficient  slope  to  prevent ponding in
low  spots.   Channel  slopes greater than  1%  will begin to  influence  the
distribution  of  the  sheet  flow on the  overland  flow slopes.  Gravity
pipe   systems  may  be  required  when unstable   soil   conditions   are
encountered,  or  when  flow  velocities are  prohibitively  erosive.   The
collection system must be designed to accept  a  realistic  amount of storm
runoff—design storms of 2 to 10  years may not  be unreasonable.
     5.5.6  Stormwater Runoff Provisions
For  slow  rate systems, control  of stormwater  runoff to  prevent erosion
is  necessary.   Terracing  of steep slopes  is  a  well  known  agricultural
practice  to  prevent  excessive   erosion.    In  general,  the  management
techniques  recommended  in  208   planning   for  nonpoint discharges  are
applicable.   Sediment  control   basins   and other nonstructural  control
                                  5-76

-------
measures, such as contour plowing, no-till fanning,  grass border strips,
and  stream  buffer  zones  can be used.  As wastewater application will
usually  be  stopped  during  storm  runoff conditions, recirculation of
storm runoff for further treatment is usually unnecessary.


For  overland  flow  systems, even the "first flush" of a high intensity
storm  should meet water quality standards.  Where the treated runoff is
to  be  disinfected  or  collected  for  other  uses,  the  quantity  of
stormwater  will  require that provisions for maximum treatment capacity
be  made.   Stormwater  in  excess of this capacity  should be allowed to
overflow  to  a planned stormwater runoff system or to natural drainage.
When  more  than  2 or 3 terraces discharge to the same collection main,
provisions  should  be  made  to  dampen  the peak runoff from storms to
minimize erosion and channel maintenance problems.


5.6  Vegetation


Vegetation in land treatment serves three major functions:

     1.   As  a nutrient extractor, vegetation concentrates nitrogen and
          phosphorus  above  the  ground  and thus makes these nutrients
          available for removal through harvest.

     2.   Plants  effectively  reduce erosion by reducing surface runoff
          velocity.    The   extension  of  root  growth  maintains  and
          increases soil permeability, and the leaf  shelter protects the
          soil  against  the  compacting  effect  of falling water.  The
          overall  effect  of various ground covers  on soil infiltration
          rates for one soil is shown in Figures 5-29 and 5-30.

     3.   For overland flow and wetlands, the vegetation, in addition to
          taking  up  nutrients,  provides  a  matrix  for the growth of
          microorganisms  that  decompose  the  organic  matter  in  the
          wastewater.
     5.6.1  Selection of Vegetation


For  slow  rate  systems,  the important considerations for agricultural
crops are:

     1.   Rate of water uptake

     2.   Rate of nitrogen and phosphorus uptake

     3.   Tolerance to potentially harmful wastewater constituents

     4.   Ease of cultivation
                                   5-77

-------
     5.   Production of a marketable crop

     6.   Minimum  net  cost  of production, after deducting the current
          market value of the crop
                              FIGURE 5-29

                   EFFECT OF SELECTED VEGETATION ON
                     SOIL INFILTRATION RATES [67]
               2 . 4
               2. 0
               I . 6
               1 . 2
               0. 8
               0 . 4
                     BARE
                     SOIL
CORN
WHEAT
                HAY
PERMANENT
 PASTURE
                  1  in/h - 2.54 cm/h
For rapid infiltration systems, the primary requirement is for a  water-
tolerant species  that  will  help  to maintain high infiltration rates.
For  overland  flow  systems, the need is for a vegetative cover that is
well   rooted  in  impermeable  soils,  is  water  tolerant  (withstands
flooding), and has a high rate of nitrogen uptake.
In general,  the  forage  and  fodder  crops are preferred because they:
(1) treat large amounts of wastewater, (2) are tolerant of variations in
wastewater  quality, and (3) require less maintenance and skill to grow.
However,  they  have a lower market value.  Successful forage crops used
to  date  include:   Reed  canary  grass, fescue, perennial rye, orchard
grass, and Bermuda grass.
                                  5-78

-------
                               FIGURE 5-30

                INFILTRATION RATES FOR VARIOUS CROPS [68] .
          2 . 8
         2 . 4
          1 . 6
      -   1.2
         0 . i
          0. 4
         0.0

OLD PERMANENT
PASTURE OR HEAVY

MULCH


4-8 YEAR  OLD
PERMANENT PASTURE
                                                        3-4 YEA R OLD
                                                        PERMANENT PASTURE
                                                        LIGHTLY  BRAZED
PERMANENT  PASTURE
MODERATELY  GRAZED

HA YS


PERMANENT  PASTURE
HEAVILY GRAZED

STRIP CROPPED OR
MIXED COVER

WEEDS OR GRAIN
CLEAN TILLED


BARE GROUND
CRUSTED
              1 i n. - 2. 54  cm
          5.6.1.1   Hydraulic  Considerations
Peak  consumptive  water   use   and   rooting  depth for various crops and
regional  areas  are  presented  in Table  5-31  as an aid in system design.
The  tolerance of individual species to  flooding is based on the rooting
depth  and  the  duration  of flooding.   Rooting depths for various crops
are  also  listed  in  Table   5-31.  The  soil  should drain and become
unsaturated  to  these  depths   during   the  irrigation resting cycle to
obtain  optimal growth.  Some saturation of the root zone by groundwater
may be tolerated, but the  usual  result is decreased plant performance.


In general, grain crops such as wheat, oats,  and barley will suffer high
yield  losses  if subjected to  soil  saturation.  Vegetable and row crops
are  slightly  more   tolerant,  but  they  are still  susceptible to damage.
                                    5-79

-------
                           TABLE  5-31

   PEAK  CONSUMPTIVE WATER USE AND  ROOTING  DEPTH  [69]
Washington,   California,      Texas,        Arkansas,    Nebraska,      Colorado,
 Columbia     San Joaquin     southern      Mississippi     eastern        western
  Basin         Valley       high plains      bottoms        part          part
Use
Depth, rate,
Crop in. in./d
Corn 42 0.27
Alfalfa 60 0.25
Pasture 24 0.29
Grain 48 0.21
Sugar
beets 36 0.26
Cotton • • 	
Potatoes 24 0.29
Deciduous
orchards • • 	
Citrus
orchards • • 	
Grapes . . ....
Annual
legumes .. 	
Soybeans . . ....
Shallow-
rooted
truck crops . . 	
Medium-
rooted . . 	
truck crops
Deep-
rooted
truck crops . . ....
Tomatoes . . ....
Tobacco .. 	
Rice .. 	
Depth,
in.
60
72
24
48
72
72
48
96
72
72


••
••

Use
rate,
in./d
0.26
0.25
0.32
0.17
0.22
0.22
0.24
0.21
0.19
0.18


	
	

Use
Depth, rate,
in. in./d
72 0.30
72 0.30
42b 0.25
72C 0.30
72 0.15
	
72 0.25

	
	
* • » •
48 0.18
'.'. '.I
	
	

Depth,
in.
30
42
36C
24

36



•
18
36
18d
18e
•• .
24
rate, Depth, rate, Depth, rate,
in./d in. in./d in. in./d
0.23 72 0.28 48 0.23
0.24 96 0.27 72 0.23
0.13 48 0.29 36 0.23
0.22
0.15 48 0.26 36 0.22
	 48 0.26 48 0.20
0.18 	
	 36 0.26 36 0.22
	 72 0.18

	
0.28 	 	
0.19 60 0.27 .. 	
0.20 	
0.12
	 36 0.22
0.17 .. 	 	 	
                             5-80

-------
TABLE 5-31
(Concluded)
State of
Wisconsin


Crop
Corn
Alfalfa
Pasture
Grain
Sugar
beets
Cotton
Potatoes
Deciduous
orchards
Citrus
orchards
Grapes
Annual
legumes
Soybeans
Shallow-
rooted
truck crops
Medium-
rooted
truck crops
Deep-
rooted
truck crops
Tomatoes
Tobacco
Rice

Depth,
in.
24
36
24
18

18

18

36





18


12


18


24
18

••
Use
, rate.
in./d
0.30
0.30
0.20
0.25

0.25
....
0.20

0.30





0.25


0.20


0.20


0.20
0.20
....
	
State of
Indiana

Depth,
in.
24
36
30




12




24


24


9


12


18
18
24
••
Use
, rate,
in./d
0.30
0.30
0.30


....

0.25

	

....
0.25


0.30


0.20


0.20


0.20
0.20
0.25
	
Piedmont Virginia, State of
Plateau"^ coastal plain New York

Depth,
in.
24
36
24
24


24
24

36


30


24


12


18


24
24
18

Use Use
rate. Depth, rate, Di.'pl.ti
in./d in. in./d in.
0.22 24 0.18 24
0.25 36 0.22 30
0.25 20 0.22
0.16 	

.... . . ....
0.21 	
0.18 18 0.18 18

0.25 36 0.22 36


0.20 	


0.18 	


0.14 	 12


0.14 18 0.16 18


0.18 	 24
0.21 24 0.18 24
0.18 18 0.17

Use
, riilo.
in./d
0.20
0.20

....

....
....
0.18

0.20


....

....



0.18


0.18


0.18
0.18
....

a.  Average daily water use  rate  during  the 6 to  10 days of the highest consumptive
    use of the season.
b.  Cool season pasture.
c.  Warm season pasture.
d.  Summer.
e.  Fall.
f.  Parts of Georgia, Alabama,  North  Carolina,.and South Carolina.
1 in.  = 2.54 cm
                                         5-81

-------
Corn  and  potatoes will   tolerate   some  flooding, possibly up to a few
days,  without  suffering   damage;   clover,   timothy,  and  rye are also
somewhat  resistant.    Grasses  (such as coastal  Bermuda, meadow, fescue,
brome,  orchard,  or   Reed canary)  are the most tolerant species and can
sustain  several weeks of  flooding  without injury.  Reed canary grass,  a
tall  cool-season perennial  with  a  rhizomatous root system, will grow in
a  very  wet,  marshy  area,  and reportedly has withstood flooding for as
long as 49 days without permanent injury [70].
          5.6.1.2   Nutrient Uptake
The  major  nutrients  essential  to plant growth are nitrogen, phosphorus,
potassium,  calcium,   magnesium,   and  sulfur.   Of these, the  prominent
constituents   in   wastewater  are  nitrogen,  phosphorus, and potassium.
Typical   uptake   rates of these elements for various crops are  listed  in
Table  5-32.   Variations noted in the amount of nutrient uptake from the
soil   can  arise   from  changes in either (1) the amount and form  of the
nutrient  present,  or  (2) the net yield of the crop.

                                TABLE 5-32

                NUTRIENT UPTAKE RATES FOR SELECTED CROPS
                          [3,  4, 5, 6, 70, 71]
                                        Uptake, lb/acre-yr
                                   Nitrogen  Phosphorus  Potassium
Forage crops
Alfalfa3
Bromegrass
Coastal Bermuda grass
Kentucky bluegrass
Quackgrass
Reed canary grass
Ryegrass
Sweet clover^
Tall fescue
Field crops
Barley
Corn
Cotton
Milomaize
Potatoes
Soybeans3
Wheat

200-480
116-200
350-600
180-240
210-250
300-400
180-250
158
135-290

63
155-172
66-100
81
205
94-128
50-81

20-30
35-50
30-40
40
27-41
36-40
55-75
16
26

15
17-25
12
14
20
11-18
15

155-200
220
200
180
245
280
240-290
90
267

20
96
34
64
220-288
29-4R
18-42
               a. Legumes will also take nitrogen from the atmosphere
                  and will not withstand wet conditions.

               1 lb/acre-yr = 1.12 kg/ha-yr
                                     5-82

-------
Nutrient content  of  a  plant  depends,  in  part,   on  the  amounts of
nutrients available to the plant.  The minimum cellular amounts required
are  about  2%  nitrogen,  0.2%  phosphorus, and 1+% potassium, but when
sufficient  quantities  are  available,  these amounts can easily double
[71,  72].   For  forage  crops  in general, the percent composition for
nitrogen can range from 1.2 to 2.8% and averages around 1.8% (dry weight
of  the  plant); but with wastewater irrigation it can range from 3.0 to
4.5% [72].
The  total uptake of nutrients from applied wastewater increases as  crop
yield  increases  (see  Figure  A-3,  Appendix A).   Crop yield increases
ranging  up  to  twofold  to fourfold have been achieved when wastewater
effluent  irrigation  is used instead of ordinary irrigation water [73].
Although   nutrient   uptake  continues  to  increase  with  yield,   the
relationship is not linear.


A  factor  that  affects  both percent nitrogen composition and yield of
forage  crops  is  stage  of  growth.   In  general,  grasses contain the
highest percentage of nitrogen during the green, fast growth stage.   The
nitrogen uptake decreases with maturity.  These effects are demonstrated
in  Figure  5-31.   For  corn  and  grasses, nitrogen uptake is very low
during  early  growth  (the  first  30 to 40 days)  and thereafter climbs
sharply.  For corn, this rise is maintained until  harvest.   For grasses,
nitrogen  uptake  reaches  a  peak  around  the  50th day and thereafter
declines.   This  suggests  that  harvesting  these grasses every 8  to 9
weeks  (for  a total  of two to three harvests per season) will  result in
maximum nitrogen uptake.
The amounts of phosphorus in applied wastewaters are usually  much  higher
than  plant  requirements.  Fortunately,  many soils  have a  high  sorption
capacity  for  phosphorus  and very little of the excess is passed on  to
the  groundwater.   Instead, it is held in the soil  and serves to  enrich
the soil [74].
Potassium is used in large amounts by many crops,  but typical  wastewater
is  relatively  deficient  in  this  element.    In some cases  fertilizer
potassium  may  be needed to provide for optimal  plant growth,  depending
on the soil  and crop grown.


The  micronutrients important to plant growth  (in  descending order)  are:
iron,  manganese,  zinc,  boron,  copper,   molybdenum, and  occasionally,
sodium,  silicon,  chloride,  and  cobalt.  Most  wastewaters  contain  an
ample  supply of these elements, and in some cases,  phytotoxicity may  be
a consideration.
                                  5-83

-------
                                FIGURE 5-31

            CROP GROWTH AND  NITROGEN  UPTAKE  VERSUS DAYS FROM
        PLANTING FOR FORAGE  CROPS  UNDER  EFFLUENT IRRIGATION [75]
    4


    3


    2

    1

    0

    4


    3

    2

    I


    0

   7 5


   50


   25

    0


   60


   60


   40

   20

    0
  n—i—I—I—I  i   r
_ SORGHUII-SUDANGRASS
  O 5 cm/wk

- B20 cm/wK
          I
          20
               40    80

               AGE.  d
                          80
                              100
                                           V
                                           a
  4


  2


  0

  4


  3

  2


  1

  0

200


t 50


1 00


 50

  0

 80


 60


 40

 20

  0
O 5  cm/»k

Q 20 cm/wK
                                                     20
                                                    J	I
                                                    40

                                                    AGE
                                                               60
                                                                    80
                                                                         1 00
      » i n ./«k - 2*. 54 cm/wk

      1 I b/ac re = 1. 1 2 k g/h a

      1 t on/ac re =2. 24 Mg/ha
          5.6.1.3   Sensitivity to Wastewater Constituents


Plant  growth  can   be   adversely  affected  by  excess salts (generally
chloride and sodium), excess  acidity,  or excess concentrations of any of
a large number of microelements,  including the micronutrients.


Tolerances  of  selected   crops   to  salinity,  boron,  and  acidity are
presented  in  Tables 5-33,   5-34,   and  5-35,  respectively.  In general,
forage  crops  are  the most tolerant,  field crops are less tolerant, and
                                    5-84

-------
vegetable  and   row crops are least tolerant.   There are many exceptions
to  this  rule,   however, and wide differences  can  be found even between
two  varieties   of  the  same  crop.   Data on  crops not listed in these
tables are available in  references  [76-78], and the local  Agricultural
Extension  Service  can  give  details  on crops  suitable for a proposed
site.
                                TABLE 5-33

                 ELECTRICAL CONDUCTIVITY VALUES RESULTING
                     IN REDUCTIONS IN CROP YIELD  [77]
                                 mmhos/cm
                                        ECe values  (saturated
                                         paste extract) for
                                          a reduction in
                                           crop yield of

Forage crops
Alfalfa
Bermuda grass
Clover
Corn (forage)
Orchard grass
Perennial rye grass
Tall fescue
Vetch
Tall wheat grass
Field crops
Barley
Corn
Cotton
Potato
Soybeans
Sugarbeets
Wheat
0%

2.0
6.9
1.5
1.8
1.5
5.6
3.9
3.0
7.5

8.0a
1.7
7.7
1.7
5.0
7.0
6.0
25%

5.4
10.8
3.6
5.2
5.5
8.9
8.6
5.3
13.3

13
3.8
13
3.8
6.2
11.0
9.5
100%

15.5
22.5
10
15.5
17.5
19
23
12
31.5

28
10
27
10
10
24
20
                   a. Barley and wheat are less tolerant during
                      germination and seedling stage.
                      not exceed 4 or 5 mmhos/cm.
ECB should
When evaporation is high, problems can  arise from the use of sprinklers.
When  water  is  applied  to  vegetative   surfaces,  excess quantities of
sodium   and  chloride  can  be absorbed through the  wet leaves and cause
leaf  burn.   Nighttime applications can  alleviate foliar absorption and
leaf burn  due to chlorides or bicarbonates.
                                    5-85

-------
                                  TABLE  5-34

                           CROP BORON TOLERANCE [77]
                                     mg/L
                     Tolerant,       Semitolerant     Sensitive,
                    1-3 mg/L boron  0.67-2 mg/L boron  <1 mg/L boron

                    Alfalfa        Barley           Citrus
                    Cotton         Corn             American elm
                    Sugarbeet      Kentucky bluegrass Berries
                    Sweetclover     Potato
                                 Tomato
                                 Wheat
                                  TABLE  5-35
                         CROP ACIDITY TOLERANCE [78]
                    Will tolerate
                    mild acidity,
                    pH 5.8 to 6.5
               Will tolerate
              slight acidity,
               pH 6.2 to 7.0
Very sensitive
  to acidity,
pH 6.8 to 7.5
                    Cotton
                    Buckwheat
                    Bentgrass
                    Millet
                    Potato
                    Poverty grass
                    Oats
                    Rye
                    Sudan grass
                    Vetch
              Corn
              Beans
              Kentucky bluegrass
              Clovers: alsike
              crimson,
              white
              Kale
              Tomato
              Soybean
              Wheat
                     red,
Alfalfa
Barley
Carrot
Sweet clover
Sugarbeet
There   are two  considerations in trace  element accumulation  in  the soil:
(1)  phytotoxicity,   and  (2)  translocation into  the food chain.   Copper,
zinc,  and nickel  are the  prime examples of elements that can  be  toxic to
some   plants  at   relatively    high  levels.  At present there  is little
definitive  evidence  that  these elements have accumulated to phytotoxic
levels  in  any  land  treatment  system [79].   The principal element of
concern  for  potential   translocation   into  the food chain  is  cadmium.
This is discussed in detail  in Appendix A.
When   selecting
should  be  made
resistant  species   to  prevent toxicity,  a  distinction
 between  accumulators  and excluders.  Accumulators will
                                       5-86

-------
tolerate  high  levels of an element while transferring large quantities
of  it  into  the harvestable portions of the plant, making it available
for  removal.   Excluders  will  also tolerate high levels, but prohibit
passage  of  the  toxifying element into the fruit, root, or leaf tissue
that is to be consumed.  For example, corn may take up cadmium but it is
mostly excluded from the grain.  In general, grain crops are superior to
vegetables in excluding heavy metals [79].


          5.6.1.4  Selection of Overland Flow Vegetation
Perennial  grasses  with  long  growing seasons, high moisture tolerance
(hydrophytic),  and  extensive  root  formation  are  best suited  to  the
process.   The  grass  should form a sod and not grow in bunches.   While
common  Bermuda,  red  top,  fescue, and rye grass all form sod, none of
these  is  always  suitable  for  all  weather conditions.  Bermuda goes
dormant  in  winter while red top, fescue, and rye grass are cool  season
grasses.   Reed  canary  grass  is  the most versatile but it is a bunch
grass.   It  should therefore be planted with a mixture of other grasses
such as red top, fescue, and rye grass.


Comparative  field  studies  at Paris, Texas, indicated that Reed  canary
grass  was  the superior grass at that location.  It demonstrated  a very
high  nutrient  uptake  capacity  and  yielded  a  high quality hay upon
harvest  [54].   Hauling the crop away during harvest provides permanent
removal   of  the  nutrients taken up during plant growth.   The harvested
grass is suitable for feeding to cattle.


          5.6.1.5  Other Vegetation
Sod,  landscape vegetation, trees, and wetlands vegetation are discussed
separately  because  of  their  unique  features.    Much of the previous
discussion will apply.
               5.6.1.5.1   Sod
Sod  farming  is the controlled growth of turf grasses for transplanting
to  lawns,  golf  courses,  and  parks.   Usually,   public access  to  the
growing  site  is  restricted  so  that  bacteriological   quality  of  the
wastewater  is  not  a  major  concern.   Because  the  sod  is  ranoved
periodically,  the  nitrogen  loadings can exceed crop uptake as well  as
soil nitrogen accumulation.
                                  5-87

-------
               5.6.1.5.2  Landscape Irrigation
Application  of wastewater on landscape areas  such  as highway  median  and
border  strips,  airport  strips,   golf  courses, parks  and recreational
areas,  and  nature-wildlife  areas  has  several advantages.   The  areas
irrigated  are  already  publicly  owned,  saving  acquisition   cost,  and
problems   associated   with   crops  for   consumption    are    avoided.
Additionally, the  maintenance  of landscape projects generally requires
less water than other vegetation (since watering  in these  cases is  based
on vegetative maintenance rather than production);  hence,  the  wastewater
can be spread over a greater area.


Although  sufficient  areas  to  accept  available   effluent are usually
available,  wastewater  distribution, especially  for roadside  rights-of-
way, can  be  a problem.  For roadside application, sprinkler  trucks  are
commonly  used; for application to golf courses,  playgrounds,  and nature
areas, fixed sprinklers are most commonly used.
               5.6.1.5.3  Woodlands Irrigation
Approximate  average  water  consumption  rates   for  native  stands   of
different tree species are given in Table 5-36.
                               TABLE 5-36

          EVAPOTRANSPIRATION OF WOODLAND AND FOREST CROPS [80]
Evapotranspiration, in./yr
M« ~f

Pines
Mixed coniferous
and deciduous
Deciduous
Mixed hardwoods
studies
32
6
58
2
Average
15
25
17
31
Range
5-34
18-34
8.5-34
27-35
                 1 in./yr = 2.54 cm/yr
Recommended  irrigation  rates  for  maintaining  desired  forest crops,
determined  from studies using wastewater irrigation, are shown in Table
5-37.   These  rates,  which  generally  agree with those in Table 5-36,
suggest  that  where water consumption is a primary consideration, pines
are at a disadvantage.
                                   5-88

-------
                                TABLE 5-37

               RECOMMENDED IRRIGATION RATES  OF  FOREST CROPS
            Species
 Maximum recommended
irrigation rate, in./wk
  Reason for limit
       Pines [75, 76, 77]


       Hardwoods

         [81]
         [82, 83]

       Douglas firs
       cottonwoods [84]
       Conifers [85]
        1

        2-4
     1 (winter)
     4 (summer)
     (104 in./yr)
                   Satisfactory tree growth rate
                   and nitrogen removal
Satisfactory nitrogen removal

Satisfactory tree growth rate
Trees grow well and consume
all available water at
this rate

Satisfactory tree growth rate
        1 in./wk =2.54 cm/wk


Pines   and   other  conifers,  however,   have  an  advantage  in  that  they
maintain  their water uptake rates  year-round, if freezing  temperatures
do  not make  the water unavailable.   Deciduous species exhibit cyclical
water   needs  with  a  very  active   growing  season  during the  summer,
followed by  a  dormant phase in the winter.   Water consumption then drops
to  a   level   of one-half to one-fourth  the summer rates, generally  less
than  1 in./wk   (2.54  cm/wk).    A major objective in silviculture is to
maintain an  adequate unsaturated  soil  zone  for the proper development of
the tree root  system.
Wood  quality  associated with  effluent-irrigated stands, as  studied by
Murphey  et al.  [86], indicates that the pulpwood characteristics  of  pine
and  oak  are  improved  via  an   increase in fibre length and cell  wall
thickness.    Structural strength,  however, appears to suffer a decrease,
rendering  the wood less suitable  for construction purposes.
For  harvesting  purposes,  cottonwood seems to show the greatest growth
response   to   effluent irrigation  [82,  83], and tree harvests  every  6 to
10  years   may  be  possible.   Eucalyptus is also a fast grower, but is
limited  to  areas  without  hard   frosts.  Studies at Stanford  Research
Institute   have suggested the creation'of eucalyptus biomass plantations
to be  harvested and burned for  the production of electricity [87].


A major limitation to the use of woodlands and forests is the  relatively
low  rates of  nutrient  uptake.    Typical rates of nitrogen  uptake for
different   forest  crops  were  listed  in  Table 5-2.  These  rates  will
usually  be  maintained  through   the growing phase (20 to 40  years) and
                                    5-89

-------
will  taper  off  as  maturity  is reached.   Conifers  as  Christmas  trees
should  be  abandoned.  The extra water and  nutrients  cause  the  trees  to
grow  upward,  rather  than  outward,  resulting  in  spindly,  unattractive
trees.
               5.6.1.5.4  Wetlands
Experience  has shown that duckweed (Lemna  minor)  and  various  species of
bulrush  (Scirpus  acustus,  Scirpus lacustris,  Scirpus  validus)  are the
most  desirable  species, based on treatment capabilities,  growth rates,
and  harvest  response  for marshes [22,  23, 88].   Cattails seem  to have
trouble   competing  with  the  bulrushes  and   duckweed  under   harvest
conditions [22].
Marsh  studies  by  the  National   Aeronautics   and  Space  Administration
concluded  that  water  hyacinths  (Eichornia  crassipes), and  to  a  lesser
extent  alligator  weed  (Alternanthera   philovernides)  are effective  in
removal of both organics and some  metals  [89, 90].
Experiments  have  been  conducted  in   Florida   with   cypress   domes as
nutrient  sinks, and they appear to be  quite  efficient [27].  Artificial
peat  beds  also  appear  to be effective,  removing  85% of  the  nitrogen,
99.3%  of the phosphorus, and 99.99% of the coliform bacteria when  grown
with a quackgrass or bluegrass cover [27,  91].
          5.6.1.6  Regulatory Constraints
Many states regulate the type of wastewater  that can  be  used  to  irrigate
some crops.  In addition, several  states  require that a  suitable crop be
planted  before land application begins [92].   In some cases  the type of
crop proposed affects the slope of the  site  that is acceptable.
          5.6.1.7  Crop Utilization
Of   crops  historically  grown  with  wastewater,   under   present   cost
conditions,  corn appears to provide the  greatest (net)  profit  [93,  94].
At  the  Muskegon  Project, the 1976 revenue  from their  corn  harvest was
approximately  $1 000 000  (see Section 7.6).   There are no restrictions
placed on the sale of this corn.
Among the trees, maples (and certain other hardwoods),  cotton  woods,  and
pines  grown  under wastewater irrigation  are  suitable  for  sale  as  pulp,
but  not  for  structural   wood  [86],   Cotton   wood and eucalyptus  are
suitable for sale as fuel  [87].
                                   5-90

-------
     5.6.2  Site Preparation and Management
It  is  critical  to  maintain the  soil-vegetation system in a healthy,
productive,  and  renovative  state.   A  successful agricultural system
requires knowledge of fanning operations, which are described briefly in
this  section.   Assistance  in  design  and planning can be provided by
local  farm advisers and land grant college extension specialists.
          5.6.2.1  Field Preparation


Procedures  for  preparing  fields  for  slow  rate  systems may include
clearing the fields of vegetative growth (bulldozing of heavy vegetation
into  piles  followed  by  burning,  or heavy stubble disking on lighter
vegetation); planing and grading, if required, and ripping, disking, and
tilling  of  the  soil  to  loosen and aerate it.  Undeveloped soils may
require  chemical  soil  amendments,  including  gypsum to reclaim sodic
soils  and  increase permeability, and lime to reduce acidity and metals
toxicity.   Determination  of  amendment  needs  is discussed in Section
5.7.3.   The  effects  of  lime on element availability are indicated in
Table  5-38.   Fertilizers  may  also  be  added for  nutrient-deficient
soils, although nutrient-rich,wastewaters often make this unnecessary.


                                TABLE 5-38

                       EFFECT OF LIME ON ELEMENT
                      AVAILABILITY IN SOIL [76, 78]
                           Elements for which liming
Reduces
availabi lity
Aluminum
Barium
Beryllium
Boron3
Cadmium
Cobalt
Copper3
Fluoride
Iron
Li thium
Manganese
Nickel
Zinc
Increases
avai labi lity
Calcium
Magnesium
Molybdenum
Nitrogen3
Phosphorus
Potassium
Sulfur3






                         a.  Minor effect on availability.
                                    5-91

-------
          5.6.2.2  Maintenance of Infiltration for Slow Rate Systems


Soil-water  infiltration  rates  can  be  reduced by surface sealing and
clogging.   The  sealing is the result of:  (1) compaction of the surface
from machine working, (2) compaction from raindrops and sprinkler drops,
(3)  a  clay  crust  caused  by  water  flowing  over  the surface (fine
particles  are  fitted  around  larger  particles  to  form a relatively
impervious seal), or (4) clogging due to suspended particles, buildup of
organic  matter,  or trapped gases.  This surface layer can be broken up
by  plowing,  cultivation,  or  any other stirring of the soil  that will
result  in increased water intake.  Tillage beyond the point of breaking
up  an  impermeable  layer  is  generally  harmful  in that it results in
further soil compaction.  The effect of surface sealing on intake can be
greatly  reduced, and possibly eliminated,  by cultivating grass or other
close-growing  vegetation.   Maintenance  of soil  organic matter through
the  use  of  high  residual crops, such as barley, and plowing under of
stubble is another step that helps maintain soil  permeability.
          5.6.2.3  Salinity Control
 If  the soil is saline (EC >4 mmhos/cm)  for most crops, control  measures
must  be  taken.  The average salt concentration of the soil  solution of
the  rooting depth is usually three times the concentration of the salts
in  the  applied  water  (in  arid  climates)  and  is  believed  to  be
representative  of  the  salinity  to  which the crop responds [77].  If
excessive  salts  build  up, the method of control is leaching by adding
enough irrigation water so that water in excess of crop needs percolates
below  the root zone, lowering the overall salinity.  The most important
zone  for  leaching  is  the  upper  quarter  of the root zone where the
primary  (40%)  water  use by the plant  occurs.   As  a  rule-of-thumb,
about  a  12 in. (30 cm) depth of water leached through a 12 in. (30 cm)
depth of soil should remove about 80% of the soluble salts.
          5.6.2.4  Crop Management


               5.6.2.4.1  Planting


'Local   extension  services  or  similar  experts  should  be  consulted
regarding planting technique and schedules.


               5.6.2.4.2  Harvesting
Harvesting  for grass crops and alfalfa involves regular cuttings, and a
decision regarding the trade-off between yield and quality must be made.
Crop  yield  will usually increase up to and beyond the flowering stage,
                                   5-92

-------
but  quality (amount of stems versus leaves and the amount of digestible
material)  is  highest  in  the younger growth stages and falls off  very
rapidly  once  the  flowering  stage is reached. ^Advice can be obtained
from local extension services.
               5.6.2.4.3  Double Cropping
Double  cropping  can extend the operating period for slow rate systems,
increase  the  economic return for the system, and increase the nitrogen
uptake capacity.
A  growing  practice  in the East and Midwest is to provide a continuous
vegetative  cover  with  grass and corn.  This "no-till" corn management
consists  of planting grass in the fall  and then applying a herbicide  in
the spring before planting the corn.  When the corn completes its  growth
cycle, grass is reseeded.  Thus, cultivation is avoided, water rates are
maximized, and nutrient uptake is enhanced.
               5.6.2.4.4  Grazing
Grazing  of  pasture  by  beef  cattle  or sheep can provide an  economic
return  for  slow  rate  systems  (see  Pleasanton,   California,  and  San
Angelo,  Texas, in Chapter 7).  This approach has also been successsfuly
pursued at the land treatment farm in Melbourne, Australia, for  the past
65 years [95],  Grazing cattle and sheep keep the vegetative cover  short
for maximum wastewater renovation efficiency.  No health hazard  has been
associated with the sale of the animals for human consumption.
Grazing  animals  do  return  nutrients  to  the  ground  in their  waste
products.  The chemical state (organic and ammonia nitrogen) and rate  of
release  of  the nitrogen reduces the threat of nitrate pollution of the
groundwater.   Much  of  the  ammonia-nitrogen volatilizes.   The organic
nitrogen  is  held  in the soil  and is slowly mineralized.  As a result,
only a portion of the nitrogen is slowly recycled.
One  precaution  that must be taken is not allowing the cattle and sheep
to  graze  on wet fields.  This would compress the ground and reduce  the
permeability  of  the  soil.   As  described  in  Chapter 7,  Pleasanton,
California,  and  San Angelo, Texas, solve the problem by using a series
of  fields  in  rotation.   Wastewater irrigation proceeds on a field as
soon  as  the  cattle  are  moved  off.  In this mariner, by the time  the
cattle are moved back onto a field to graze, it has had several weeks to
dry out and firm up.
                                    5-93

-------
Another  concern  is  the physical  contact between the udders  of  milking
animals  (cows,  goats)  and  pastures  irrigated  with wastewater.   This
could  represent  a  direct  vector to human  food  supplies  and should  be
avoided.
5.7  System Monitoring
Monitoring
significant
monitoring
determine
environment
components
wastewater,
i n   some
wastewater.
of  land  treatment  systems   involves   the   observation   of
 changes  resulting from the  application of  wastewater.   The
data  are  used  to confirm environmental  predictions  and to
if  any  corrective  action   is   necessary  to   protect   the
 or  maintain  the  renovative  capacity of  the  system.   The
 of  the  environment  that   need  to   be observed  include
groundwater, and soils upon which wastewater is  applied and,
cases,  vegetation  growing   in   soils   that are  receiving
     5.7.1  Water Quality
Monitoring  of  water  quality for land application systems is  generally
more  involved  than for conventional  treatment systems because nonpoint
discharges  of  system  effluent  into  the   environment  are  involved.
Monitoring  of  water  quality  at  several   stages  of a land  treatment
process  may  be  needed  for  process  control.   These stages   may  be:
(1) applied wastewater, (2) renovated  water,  and (3) receiving   waters--
surface water or groundwater.
          5.7.1.1  Applied Wastewater
The  water  quality  parameters  and the frequency of analyses  will  vary
from  site to site depending on the regulatory  agencies involved  and the
nature  of  the applied wastewater.  The measured parameters  may  include
(1) those  that may adversely affect receiving  water quality  either  as  a
drinking  water supply or an irrigation water supply, (2)  those required
by  regulatory agencies, and (3) those necessary for system control. An
example  of  a  suggested  water  quality monitoring program  for  a large
scale slow rate system is presented in Table  5-39.
          5.7.1.2  Renovated Water
Renovated  water  may be recovered as runoff in  an overland flow system,
or  as  drainage  from underdrains or groundwater from recovery wells  in
slow  rate  and  rapid infiltration systems.  Point discharge to surface
waters must satisfy the NPDES permit.
                                  5-94

-------
                                 TABLE  5-39

                       EXAMPLE MONITORING PROGRAM FOR
                          A LARGE SLOW  RATE SYSTEM
                                       Frequency of analysis
                                                    Groundwater
                          Applied             Onsite  Perimeter Background
Parameter wastewater
Flow
BOD or TOC
COO
Suspended solids
Nitrogen, total
Nitrogen, nitrate
Phosphorus, total
Col i forms, total
PH
Total dissolved
solids
Alkalinity
SAR
Static water
level
Note: C = Continuously
D = Daily
Q = Quarterly
W = Weekly
C
W
W
W
W
••
M
W
D

M
M
M

••




Soil Plants wells
..
Q
Q
..
2A A 0
0
2A A Q
0
Q .. 0

0
0
Q .. Q

M
2A = Two samples per
A = Annually
M = Monthly

wells
..
Q
Q
••
0
Q
0
Q
0

0
Q
Q

M
year



wells
• •
Q
Q
••
0
0
Q
0
0

Q
Q
Q

M




          a.  Wastewater applied and groundwater should be tested initially
             and periodically thereafter,  as appropriate, for heavy metals,
             trace organics, or other constituents of environmental concern.
           5.7.1.3  Groundwaters
In  groundwaters,  travel  time of constituents is slow and mixing  is not
significant  compared  with   surface  waters.    Surface   inputs   near  a
sampling   well   will  move vertically and arrive at the well much  sooner
than   inputs  several  hundred  feet  away   from  the  well.   Thus, the
groundwater  sample  represents  contributions  from  all  parts   of the
surface   area with each contribution arriving  at the well at a different
time.   A  sample  may  reflect surface inputs from several years  before
sampling   and  have  no   association  with   the land application  system.
Consequently,  it  is  imperative  to obtain adequate background  quality
data and  to locate sampling  wells so that response times  are minimized.
                                      5-95

-------
If  possible,  existing background data  should  be  obtained  from  wells  in
the  same  aquifer  both  beyond  and  within   the  anticipated   area  of
influence  of  the  land  application  system.   Wells  with  the longest
history  of  data are preferable.   Monitoring of background wells should
continue  after  the  system  is  in   operation to   provide   a  base for
comparison.


In  addition  to  background  sampling,   samples   should  be   taken from
groundwater  at  perimeter  points  in  each  direction   of  groundwater
movement  from  the site.  In locating the  sampling  wells,  consideration
must  be  given  to the position of the  groundwater  flow  lines resulting
from  the  application  [96, 97].   Perimeter  wells   should  be   located
sufficiently  deep  to  intersect  flow   lines  emanated  from below the
application area but not so deep as to prolong  response times.


A schematic showing correct and incorrect groundwater sampling locations
is   given   in  Figure  5-32;   monitoring  points  for   a  hypothetical
application  site  are also shown.  If samples  are taken  at A and B, the
groundwater  flow  lines from the application area indicate that treated
effluent  would  reach  these  points.  It  may  require several years for
treated  effluent  to  reach  point C because  the flow lines are a long
distance from the application surface.  If  samples were taken from point
D,  mixing with surface water could make results invalid  for  groundwater
characterization.
A  groundwater flow model  that predicts groundwater movement in  the  area
of  influence  of  the  site will  be helpful  in  locating  sampling  wells.
Guidelines  for  sampling   well  construction  and sampling procedures are
given by Blakeslee [98].
In  addition  to quality, the depth to groundwater should be measured  at
the sampling wells to determine if the hydraulic  response of the  aquifer
is  consistent with what was anticipated.   For slow rate systems,  a  rise
in  water  table  levels  to  the root zone would necessitate corrective
action  such  as reduced hydraulic loading  or adding underdrainage.  The
appearance  of  seeps  or perched groundwater tables might also  indicate
the need for corrective action.
     5.7.2  Soils Management


In  some  cases,  application  of  wastewater to the land will  result in
changes  in  soil properties.  Results of soil  sampling and testing  will
serve as the basis for deciding whether or not soil  properties  should be
adjusted  by  the  application  of chemical  amendments.  Soil  properties
that  are  important  to  management  include:   (1)  ph, (2) exchangeable
sodium percentage, (3) salinity, (4) nutrient status, and (5)  metals.
                                   5-96

-------
                              FIGURE  5-32

                SCHEMATIC OF GROUNDWATER FLOW LINES AND
              ALTERNATIVE MONITORING  WELL LOCATIONS [95]
                                   LAND TREATMENT
                                                             CREEK
       RIVER
        LECENB
                                     IMPERVIOUS
                                       LAYER
C-0
            GROUNDWATER TABLE

            UNSATURATED  FLOW


            SATURATED  FLOW


            INCORRECT  MONITORING
             LOCATIONS
      A-B   CORRECT MONITORING
             LOCATIONS
          5.7.2.1   pH
Soil  pH below  5.5  or  above 8.5 generally is harmful  to most plants (see
Table  5-35).    Below   pH  6.5 the capacity of  soils  to retain metals is
reduced  significantly, the soil  above pH 8.5 generally indicates a high
sodium  content  and   possible  permeability  problems.   If wastewaters
contain  high concentrations of sodium, the soil  pH may rise in the long
term.  A pH adjustment program should be based  on the recommendations of
a professional  agricultural consultant or county  or  state farm advisor.
                                     5-97

-------
          5.7.2.2   Exchangeable Sodium Percentage


When the percentage of sodium on the soil  exchange complex  (ESP)  exceeds
10  to  15%,  problems  with reduced soil  permeability  can  occur.  Sodic
soil  conditions  may  be corrected by adding soluble calcium to the soil
to displace the sodium on the exchange and removing the displaced sodium
by  leaching.   Calcium  may  be applied  in  the form  of gypsum  (CaSCK)
either  as  a  dry   powder  or dissolved in the applied wastewater.  The
amount  of  gypsum   to  apply  may  be determined by a  laboratory gypsum
requirement  test as described in the standard references.   If a  soil  is
calcareous,  that   is, containing calcium in the form of insoluble salts
such  as  carbonates,   sul fates,  or  phosphates,  the   calcium  may  be
solubilized  and  made available for sodium displacement by the addition
of  acidulating  chemical s--sul fur,  sulfuric acid, or  iron and aluminum
sulfate.   A  comparison  of  these  chemicals to gypsum is presented in
Table 5-40.
                                TABLE 5-40

                 A COMPARISON OF CHEMICALS TO GYPSUM  [99]
                                           Tons equivalent to
                        Amendment             1 ton of gypsum


                  Sulfur, S                         0.19

                  Nitrosol, 20% N,  40% S               0.47

                  Sulfuric acid, H2S04                0.57


                  Limestone, CaCOj                    0.58


                  Lime-sulfur, 24%  S                  0.79

                  Gypsum, CaS04 •  2H20                1.00


                  Alum, A12(S04)3  • 17 H20             1.29


                  Ferrous sulfate,  FeS04 • 7 H20         1.61
                  1 ton = 0.907 Mg


          5.7.2.3  Salinity
The  levels  at  which salinity becomes harmful to  plant growth depend on
the  type  of crop.   Salinity in the root zone is  controlled by leaching
soluble salts to the subsoil  or drainage system  (see  Section 5.6.2.3).
                                    5-98

-------
          5.7.2.4  Nutrient and Trace Element Status
The   nutrient  status  of  the  soil   and  the  need  for  supplemental
fertilizers  should  be  periodically assessed.  The levels of metals in
the  soil  may be the factor determining the ultimate useful  life of the
system.   University  agricultural   extension  services  may provide the
service or recommend competent laboratories.


     5.7.3  Vegetation
Plant tissue analysis is probably more revealing than soil  analysis with
regard   to  deficient  or  toxic  levels  of   elements.    All   of  the
environmental   factors  that  affect  the  uptake  of  an   element  are
integrated  by  the  plant,  thus  eliminating  much  of  the complexity
associated with interpretation of soil  test results.  If a  regular plant
tissue  monitoring  program  is established, deficiencies  and toxicities
can  be  determined  and  corrective  action  can  be  taken.   Detailed
information  on  plant  sampling  and  testing may be found in Walsh and
Beaton [100] and Melsted [101].
5.8  Facilities Design Guidance
The  purpose  of  this  section  is  to  provide  guidance on aspects  of
facilities   design .  that  may  be  unfamiliar  to  some  environmental
engineers.

     •    Standard surface  irrigation  practice is to produce longitudi-
          nal  slopes of 0.1  to 0.2% with  transverse slopes not exceeding
          0.3%.

          Step 1.    Rough  grade   to  +   0.15  ft (5  cm)  at 100  ft  (30  m)
                    grid stations.

          Step 2.    Finish  grade   to  +  0.10  ft (3  cm)  at 100  ft  (30  m)
                    grid   stations  with   no   reversals  in slope between
                    stations.

          Step 3.    Land   plane with a 60 ft  (18  m)  minimum  wheel base,
                    land plane to  a "near perfect"  finished grade.

     •    Specifications   are   available   from  the  SCS  for agricultural
          land leveling [102].

     •    Overland  flow   slopes should be graded  to specification twice
          and  checked for  bulk density  and degree  of compaction  to en-
          sure  relatively  uniform conditions  and  prevent settlement
          during initial operation.

     •    If  the  site is  large and intense rainfall  is  likely to  occur,
          a  minimum  amount of finished  slope should be prepared  at any
          one  time.


                                   5-99

-------
•    Access to sprinklers or distribution  piping  should be provided
     every 1  300 ft (390 m)  for convenient maintenance.

•    Both  asbestos-cement  and  PVC   irrigation   pipe   are  rather
     fragile and require care in handling  and  installation.

•    Topsoil    should  be  stripped  and preserved   during  initial
     overland flow site grading, then replaced on the  slope.

•    Reed canary grass requires about 1 year to become  established.
     A  companion  crop  of orchard or rye grass  is recommended  for
     the first year.

•    Tail water  return  systems  should be  designed  to distribute
     collected water to all  parts of  the field, not consistently to
     the same area.

•    Screening  should  be provided for distribution pumping  on  the
     suction side to help prevent nozzle plugging.

•    Diaphragm-operated globe valves  should be used for controlling
     flow to laterals.

•    All  electric  equipment  should  be  grounded, especially when
     associated with center pivot systems.

•    Automatic  controls  can  be  electrically,   hydraulically, or
     pneumatically  operated.   Solenoid   actuated,   hydraulically
     operated (by the wastewater)  valves  with small  orifices will
     clog from the solids.

•    Use  36  in.  (1  m)  or larger  valve boxes  made  of corrugated
     metal,  concrete,  fiberglass,  or pipe material.   Valve boxes
     should extend 6 in. (15 cm) above grade  to exclude stormwater.

•    Low pressure shutoff valves should be used to avoid continuous
     draining of the lowest sprinkler on the  lateral.

•    Automatic  operation can be controlled  by timer clocks.   It is
     important  that  when  the timer shuts  the system down for  any
     reason  that the field valves close automatically and that  the
     sprinkling   cycles   resume  as  scheduled  when  sprinkling
     commences.   The  clock  should  not reset to time zero when an
     interruption occurs.

•    High  flotation  tires  are  recommended   for  land  treatment
     systems.   Allowable  soil contact pressures for center pivot
     machines are presented in Table  5-41.

•    Underdrains  are  only effective in   saturated soil.  If  they
     are placed in a well to moderately-well  drained soil above  the
     water table, they will not recover any water.
                              5-100

-------
                      TABLE  5-41


            ALLOWABLE SOIL CONTACT PRESSURE



              % fines   Contact pressure, lb/in.2


                20             25

                40             16

                50             12
              Note: To illustrate the use of this
              table, if 20% of the soil fines
              pass through a 200-mesh screen, the
              contact pressure of the supporting
              structure to the ground should be no
              more than 25 lb/in.2.  If this is
              exceeded, one can expect wheel
              tracking problems to occur.
Perforated  continuous  plastic  pipe is generally more econo-
mical   than clay tile or  bell  spigot pipe for  underdrains.

A filter   sock  placed over  plastic drain pipe will  help pre-
vent clogging--a gravel envelope   is unnecessary.    Encrusting
by iron,  etc., can prove  to  be  a  problem over  time.

Plastic  drainage  pipe with cut  or preformed  openings is less
likely  to plug than pipe  with  punched openings.

Maximum   depth   of   placement    for  standard   agricultural
continuous drain-tile trenches  is 5.5 ft (1.6  m).   Bucket-type
trenches  are needed to place tile deeper.

Intensive  shallow  drainage may be more economical  than deep
widely-spaced drains.

Disking or harrowing soil  surface about once per year can help
maintain  infiltration capacity.

Plowing  in  "heavy" soils will develop a plowpan  layer at the
tip depth of the plow.  Ripping or deep plowing at 2 to 4 year
intervals  may  be necessary.
                          5-101

-------
5.9  References

 1.  Alternative Waste Management Techniques for Best  Practicable   Waste
     Treatment.   US  Environmental   Protection  Agency,   Office  of  Water
     Program Operations.  EPA-430/9-75-013.   October 1975.

 2.  National    Interim   Primary   Drinking   Water   Regulations.     US
     Environmental  Protection Agency.   40  CFR 141.   December 24,  1975.

 3.  Evaluation of Land Appl ication  Systems.    Office   of   Water  Program
     Operations,   Environmental   Protection  Agency.   EPA-430/9-75-001.
     March 1975.

 4.  Powell,  G.M.   Design  Seminar  for  Land  Treatment of  Municipal
     Wastewater Effluents.   EPA  Technology Transfer  Program.    (Presented
     at  Technology Transfer Seminar.   1975.)   75 p.

 5.  Clapp, C.E.  et al.   Nitrogen   Removal   from   Municipal   Wastewater
     Effluent  by  a  Crop  Irrigation  System.   Minnesota Agricultural
     Experiment Station Paper No.  9576.   1976.

 6.  Larson, W.E.  Personal  Communication.   1976.

 7.  Iskandar,  I.K.,   R.S.   Sletten,   D.C.  Leggett,  and   T.F.  Jenkins.
     Wastewater  Renovation  by   a  Prototype  Slow   Infiltration    Land
     Treatment  System.   Corps  of  Engineers,   U.S.  Army Cold  Regions
     Research and Engineering Laboratory.    CRREL Report 76-19.   Hanover,
     N.H.  June 1976.

 8.  Pratt, P.P.  Quality  Criteria   for  Trace  Elements   in   Irrigation
     Waters.   University  of California, Department of Soil Science and
     Agricultural Engineering, Riverside.  1972.

 9.  National   Academy  of  Science.    Water   Quality   Criteria    1972.
     Ecological  Research  Series.   US Environmental  Protection Agency.
     Washington, D.C.  Report No.  R3-73-033.   March 1973.

10.  Lance, J.C.  and C.P.   Gerba.  Nitrogen,  Phosphate and Virus Removal
     from Sewage Water During Land Filtration.   In:   Progress  in   Water
     Technology.   Vol.    9,   Pergamon Press.   Great Britain.   1977.  pp.
     157-166.

11.  Pound, C.E.  and R.W.   Crites.   Wastewater Treatment   and  Reuse   by
     Land  Application.    Volumes  I  and  II.    Environmental  Protection
     Agency, Office of Research  and  Development.  August 1973.

12.  Bouwer,  H.,  R.C.    Rice,   E.D.    Escarcega,    and    M.S.    Riggs.
     Renovating   Secondary   Sewage   by    Ground   Water   Recharge  With
     Infiltration Basins.     Environmental  Protection  Agency,  Office   of
     Research and Monitoring. Project No.  16060 DRV.  March 1972.  102  p.

13.  Baillod,  C.R., et al.   Preliminary Evaluation   of 88 Years   Rapid
     Infiltration   of   Raw  Municipal   Sewage at Calumet,  Michigan.
     In:  Land as a Waste Management Alternative.    Loehr,  R.C. (ed.) Ann
     Arbor, Ann Arbor Science.  1977.   pp  435-45U.


                                 5-102

-------
14.   Aulenbach,  D.B.,  T.P.   Glavin,  and J.A.  Romero  Rojas.   Protracted
     Recharge of  Treated  Sewage  into Sand, Part  I  - Quality Changes in
     Vertical Transport Through  the  Sand.  Ground Water.   12(3) :161-169,
     May-June 1974.

15.   Pound,  C.E., R.W.   Crites,  and  J.V.  Olson.    Long-Term  Effects  of
     the  Rapid   Infiltration  of Municipal Wastewater.  (Presented at the
     8th International  Conference of  the  International  Association  on
     Water Pollution Research,   Sydney,  Australia.  October 1976.)

16.   Satterwhite,  M.B.     and   G.L.    Stewart.     Evaluation   of   an
     Infiltration-Percolation  System   for  Final   Treatment  of  Primary
     Sewage  Effluent in  a  New  England  Environment.  In:  Land as a  Waste
     Management   Alternative.    Loehr,   R.C.   (ed.)  Ann Arbor, Ann Arbor
     Science. 1977.   pp 435-450.

17.   Thomas, R.E., B.   Bledsoe,  and  K.   Jackson.  Overland Flow Treatment
     of   Raw    Wastewater   with     Enhanced     Phosphorus    Removal.
     EPA-600/2-76-131.     Environmental   Protection  Agency,  Office  of
     Research and Development.   June 1976.

18.   Thomas,  R.E.   Personal  Communication.  March 1977.

19.   Hunt,  P.G.   and Lee, C.R.   Land Treatment of Wastewater by  Overland
     Flow   for  Improved Water   Quality.   Biological  Control  of Water
     Pollution.   University of Pennsylvania.  1976.   pp 151-160.

20.   Lee,  C.R.,  et al.   Highlights   of   Research  on  Overland  Flow  for
     Advanced Treatment of  Wastewater.   U.S.  Army Engineer Waterways
     Experiment  Station.  Miscellaneous  Paper Y-76-6.  November 1976.

21.  'Carlson, C.A., P.G.  Hunt,  and  T.B.   Delaney,  Jr.   Overland  Flow
     Treatment of Wastewater.  Army  Engineer Waterways Experiment Station.
     Miscellaneous Paper Y-74-3.  August 1974.

22.   Small,  M.M.  Marsh/Pond Sewage  Treatment Plants.   In:   Proceedings
     of the  National Symposium on Freshwater Wetlands and Sewage Effluent
     Disposal.   University of   Michigan.   Ann  Arbor,  May  1976.   pp
     197-214.

23.   Spangler, F.L.  et  al. Artificial  and Natural Marshes as Wastewater
     Treatment  Systems  in Wisconsin.  In:  Proceedings of the National
     Symposium  on Freshwater  Wetlands  and  Sewage  Effluent Disposal.
     University  of Michigan.   Ann Arbor,  May 1976.   pp 215-240.

24.   U.S.   Department  of the Interior,  Bureau of Reclamation.  Wastewater
     Reclamation and Reuse  Pilot Demonstration  for  the  Suisun  Marsh.
     Progress Report.  August  1975.

25.   Whigham, D.F.  and R.L.  Simpson.   Sewage  Spray  Irrigation  in  a
     Delaware River Freshwater Tidal   Marsh.   In:    Proceedings  of  the
     National  Symposium on  Freshwater Wetlands  and  Sewage  Effluent
     Disposal.   University of   Michigan.   Ann  Arbor,  May  1976.   pp
     119-144.
                                 5-103

-------
26.   Hartland-Rowe, R.C.B.  and  P.B.   Wright.    Swamplands  for  Sewage
     Effluents,  Final  Report.  Environmental-Social  Committee,  Northern
     Pipelines, Task Force  on  Northern  Oil   Development.    Report  No.
     74-4.  May 1974.

27.   Stanlick, H.T.  Treatment of Secondary Effluent Using  a  Peat  Bed.
     In:  Proceedings of the National Symposium   on  Freshwater  Wetlands
     and  Sewage  Effluent Disposal.  University of Michigan.  Ann Arbor,
     May 1976.  pp 257-268.

28   Ewel, K.C.  Effects of Sewage  Effluent  on  Ecosystem   Dynamics  in
     Cypress  Domes.   In:   Proceedings  of  the  National   Symposium on
     Freshwater Wetlands and Sewage  Effluent  Disposal.   University  of
     Michigan.  Ann Arbor, May 1976.  pp 169-198.

29.   Odum,  H.T.   et  al.   Recycling  Treated  Sewage  through   Cypress
     Wetlands in Florida.  University of Florida,  Center  for Wetlands,
     Gainesville.  December 1975.

30.   Lindsley,  D.,  T.   Schuck,  and  F.   Stearns.    Productivity  and
     Nutrient Content of Emergent Macrophytes in Two  Wisconsin  Marshes.
     In:   Proceedings  of  the National Symposium on Freshwater  Wetlands
     and Sewage Effluent Disposal, University  of  Michigan,  Ann  Arbor.
     May 1976.  pp 51-77.

31.   Demirjian, Y.A.  Land Treatment of Municipal  Wastewater  Effluents,
     Muskegon County Wastewater System.  Environmental  Protection Agency,
     Technology Transfer.  1975.

32.   Reed, S.C., et al.  Pretreatment Requirements for  Land  Application
     of  Wastewaters.  Extended Abstract for ASCE 2nd National  Conference
     on  Environmental  Engineering  Research,   Development   and   Design,
     University of Florida.  1975.

33.   Crites, R.W.  and A.  Uiga.  Evaluation of Relative  Health   Factors
     for   Wastewater   Treatment  Processes.    Environmental  Protection
     Agency.  Office of  Water  Program  Operations.   EPA  430/9-77-003.
     June 1977.

34.   Thomas, R.E., K.  Jackson, and L.  Penrod.   Feasibility of  Overland
     Flow  for  Treatment  of  Raw  Domestic  Wastewater.   Environmental
     Protection Agency, Office of Research and  Development.   EPA-660/2-
     74-087.  July 1974.

35.   Gilde, L.C.  Land Application Systems  of  Food  Processing   Waters.
     In:   Proceedings  of  the  Sprinkler Irrigation Association, Annual
     Technical Conference, Atlanta, February 23-25, 1975.  pp 176-195.

36.   Pretreatment of Pollutants Introduced Into Publicly Owned Treatment
     Works.   Environmental  Protection  Agency,  Office of  Water Program
     Operations.  October 1973.
                                 5-104

-------
37.   Schaub, S.A., et al.  Land Application of Wastewater:  The  Fate  of
     Viruses,  Bacteria,  and  Heavy Metals at a Rapid Infiltration Site.
     U.S.   Army  Medical   Bioengineering   Research   and   Development
     Laboratory.  Fort Detrick, Md.  May 1975.

38.   Whiting, D.M.  Use  of Climatic Data in Estimating Storage  Days  for
     Soil  Treatment Systems.  Environmental Protection Agency,    Office
     of Research and Development.  EPA-IAG-D5-F694.  1976.

39.   Whiting, D.M.  Use  of Climatic Data  in  Design  of  Soil  Treatment
     Systems.   EPA-660/2-75-018.    Environmental   Protection   Agency,
     Office of Research  and Development.  July 1975.

40.   Palmer, W.C.  Meteorological Drought, Research Paper No.  45.   U.S.
     Department  of  Commerce, Weather Bureau, Washington, D.C.  February
     1965.  58p.

41.   Pound, C.E., R.W.   Crites, and D.A.   Griffes.   Land  Treatment  of
     Municipal  Wastewater  Effluents,  Design  Factors-I.  Environmental
     Protection Agency,  Technology Transfer.  October 1975.

42.   Hagan,  R.M.,  H.R.   Haise,  and  T.W.   Edminster.   Irrigation  of
     Agricultural Lands.  Agronomy Series  No.   11.   Madison,  American
     Society of Agronomy.  1967.

43,  Vegetative Water Use in  California,  1974.   Bulletin  No.   113-3,
     State of California Department of Water Resources.  April 1975.

44.  Booher, L.J.   ana  G.V.   Ferry.   Estimated  Consumptive  Use  and
     Irrigation  Requirements of Various Crops.  University of California
     Agricultural Extension Service, Bakersfield, Ca.  March 10, 1970.

45.  Statutes ana Regulations  Pertaining  to  Supervision  of  Dams  and
     Reservoirs.   State  of  California  Department  of Water Resources,
     Division of Safety  of Dams, Rev.  1974.

46,  U.S.  Department of the Interior, Bureau of Reclamation.  Design  of
     Small  Dams.   Second  Edition,  1973.   U.S.   Government  Printing
     Office.

47.  Booher, L.J.   Surface  Irrigation.   FAO  Agricultural  Development
     Paper  No.   95.    Food  and Agricultural Organization of the United
     Nations.  Rome.  1974.

48.  Lawrence,  G.A.   Furrow  Irrigation.   Leaflet  No.    344.    U.S.
     Department  of  Agriculture,  Soil  Conservation  Service.  December
     1953.

49.  McCulloch, A.W.  et al.  Lockwood-Ames  Irrigation  Handbook.   W.R.
     Ames Company, Gering,   1973.
                                  5-105

-------
50.   Merriam,  J.L.   Irrigation  System  Evaluation   and   Improvement.
     California  State  Polytechnic  College.    Blake  Printery, San Luis
     Obispo,   August 1968.

51.   Border  Irrigation.  Irrigation, Chapter 4.   SCS National  Engineering
     Handbook,   Section   15.    US  Department  of  Agriculture,    Soil
     Conservation Service.  August 1974.

52.   Bouwer, H.  Infiltration-Percolation Systems.  In:  Land Application
     of Wastewater.  Proceedings of a Research Symposium Sponsored by the
     USEPA,  Region III,  Newark, Delaware,  November 1974.  pp 85-92.

53.   Bouwer,  H.,  R.C.   Rice,  and  E.D.   Escarcega.   High-Rate  Land
     Treatment I:  Infiltration and Hydraulic  Aspects  of  the  Flushing
     Meadow   Project.   Jour.   WPCF. 46:834-843,   May 1974.

54.   C.W.  Thornthwaite  Associates.   An  Evaluation  of  Cannery   Waste
     Disposal   of  Overland  Flow  Spray  Irrigation.   Publications  in
     Climatology, 22, No.  2.  September 1969.

55.   Pillsburg,  A.F.   Concrete  Pipe  for  Irrigation.   Circular  418,
     University of California College of Agriculture.  November  1952.

56.   Hart, W.E.  Irrigation System Design.   Colorado  State  University,
     Department  of  Agricultural  Engineering.    Fort Collins, Colorado.
     November 10, 1975.

57.   Turner, J.H.  and C.L. Anderson,  Planning for an Irrigation System.
     American  Association  for  Vocational  Instructional  Materials  in
     Cooperation  with  the  U.S.   Department   of   Agriculture,    Soil
     Conservation Service.  Athens,   June 1971.

58.   Norum,  E.M.  Design and Operation of  Spray  Irrigation  Facilities.
     In:   Land  Treatment  and  Disposal  of  Municipal  and  Industrial
     Wastewater,  Sanks, R.L.  and T.  Asano (ed.).  Ann Arbor, Ann Arbor
     Science.  1976.  pp 251-288.

59.   Sprinkler  Irrigation.   Irrigation,  Chapter  11.    SCS   National
     Engineering  Handbook, Section 15.  U.S.   Department of Agriculture,
     Soil Conservation Service.  July 1968.

60.   Skaggs, R.W.  A Water Management Model for High Water  Table  Soils.
     (Presented   at   the  1975  Winter  Meeting,  American  Society  of
     Agricultural Engineers, Chicago, 111.  December 15-18, 1975.)

61.   Skaggs, R.W.  Evaluation of  Drainage-Water  Table  Control  Systems
     Using   a  Water  Management  Model  (Presented at the Third National
     Drainage Symposium, Chicago, 111.  December 13-13, 1976.)

62.   Luthin, J.N.  (ed.).   Drainage  of  Agricultural  Lands.   Madison,
     American Society of Agronomy.  1957.
                                 5-106

-------
63.   Drainage  of  Agricultural  Land.   A  Practical  Handbook  for  the
      Planning, Design,  Construction,  and  Maintenance  of  Agricultural
      Drainage   Systems.     U.    S.   Department  of  Agriculture,  Soil
      Conservation Service.   October  1972.

64.   Bouwer, H.  Ground Water Recharge Design for Renovating Waste Water.
      J.   San.  Eng., ASCE, 96:No.(1):59-73.  February 1970.

65.   Houston, C.E.  and R.O.  Schade.  Irrigation  Return-Water  Systems.
      Circular No.  542, University of California Division of Agricultural
      Sciences.  November  1966.

66.   Thomas, R.E., J.P.   Law, Jr., and C.C.  Harlin,  Jr.   Hydrology  of
      Spray-Runoff  Wastewater  Treatment.   Journal of the Irrigation and
      Drainage  Division,  Proceedings  of   the   ASCE.    96(3):289-298,
      September 1970.

67.   Stone, J.E.  Role of Vegetative Cover.   In:   Land  Application  of
      Wastes - An Educational Program, Cornell University, May 1976.

68.   Hart, R.H.  Crop Selection and Management.  In:  Factors Involved in
      Land Application  of   Agricultural  and   Municipal   Wastes.    US
      Department    of   Agriculture,   Agricultural   Research   Service,
      Beltsville, MD.  July 1974.  pp 178-200.

69.   Soil-PIant-Water Relationship.  Irrigation, Chapter 1.  SCS National
      Engineering Handbook, Section 15.  U.S.  Department of  Agriculture,
      Soil Conservation Service.  March 1964.

70. ,  A Guide to  Planning  and  Designing  Effluent  Irrigation  Disposal
    i  Systems  in  Missouri.   University  of Missouri Extension Division.
      March 1973.

71.   Palazzo, A.J.  Land Application of Wastewater -  Forage  Growth  and
      Utilization  of  Applied N,P,K.  Corps of Engineers, U.S.  Army Cold
      Regions Research and Engineering Laboratory.  Hanover,  N.H.   April
      1976.  15 p.

72.   Johnson,  R.D.,  R.L.   Jones,  T.D.   Hinesly,  and  D.J.    David.
      Selected  Chemical  Characteristics  of Soils, Forages, and Drainage
      Water from the Sewage Farm Serving Melbourne,  Australia.   US  Army
      Corps of Engineers, January 1974.

73.   Sopper, W.E.  and L.T.  Kardos.  Vegetation Responses to  Irrigation
      with Treated Municipal  Wastewater.  In:  Recycling Treated Municipal
      Wastewater  and  Sludge  through  Forest and Cropland.  Sopper, W.E.
      and  L.T.  Kardos, (ed.).  University Park,  The  Pennsylvania  State
      University Press.  1973.  pp 271-294.
74.
Kardos, L.T.  ana J.E.  Hook.  Phosphorus Balance in Sewage Effluent
Treated  Soils.   Journal   of  Environmental   Quality.    5(1):87-90,
January-March 1976.
                                 5-107

-------
75.
76.
77.
78.
79.
80.
81.
82.
83.
84.



85.


86.
Overman, A.R., and A.  Ngu.   Growth  Response  and  Nutrient Uptake  by
Forage  Crops  Under Effluent Irrigation.   Commun.  Soil Science and
Plant Analysis.  6:81-93,  1975.

Chapman, H.D.  and P.P.  Pratt.    Methods   of  Analysis  for  Soils,
Plants,   and   Waters.    University  of   California,   Division  of
Agricultural  Sciences.   1961.
Ayers, R.S.  and D.W.   Westcot.    Water
Food and Agriculture Organization  of  the
Drainage Paper No.   29.   Rome.   1976.
                           Quality   for  Agriculture.
                           United Nations.   Irrigation
Western Fertilizer Handbook.   Soil
Fertilizer Assoc.  The  Interstate
Danville, 111.  1975.  250 p.

Sutton, D.L.  and  W.H.    Ornes.
Sewage  Effluent  Using  Duckweed.
4(3):367-370, July-September  1975.
                     Improvement  Committee, California
                      Printers  and  Publishers,   Inc.
                     Phosphorus   Removal   from  Static
                     Journal  of  Environmental Quality.
Kozlowski, T.
Plant  water
1968.
 T.  (ed).   Water Deficit  and Plant  Growth,   Vol.    II:
Consumption  and  Response.   New  York,  Academic Press.
Kardos, L.T., W.E.  Sopper,  E.A.   Myers,   R.R.    Parizek,  and  J.B.
Nesbitt.   Renovation  of  Secondary   Effluent   for  Reuse  as a Water
Resource.  Environmental  Protection Agency,  Office of  Research  and
Development.  EPA-660/2-74-016.   February  1974.

Sutherland, J.C.  et al.   Irrigation  of  Trees and Crops with  Sewage
Stabilization  Pond  Effluent in  Southern  Michigan.   In:   Wastewater
Use in the Prediction of  Food  and Fiber,   EPA-660/2-74-041.   June
1974.  pp 295-315.

Sopper, W.E.  and L.T.  Kardos.   Vegetation  Responses  to   Irrigation
with Treated Municipal Wastewater.   In:  Recycling Treated Municipal
Wastewater  and  Sludge  through   Forest and Cropland.  Sopper, W.E.
and L.T.  Kardos, (ed.).   University  Park,   The   Pennsylvania  State
University Press.  1973.   pp 271-294.

Cole, D.W., et al.  A Study of the Interaction   of   Wastewater  With
Terrestial Ecosystems.  Second Annual  Report to  the  U.S.   Army Corps
of Engineers.  Draft.  1976.
Alverson, J.E.  Wastewater Irrigation  and Forests.
6, No.  4:29-36,  1975.
                                      Water   Spectrum,
Murphey,  W.K.,  R.L.   Brisbin,   W.J.    Young,
Anatomical and Physical Properties of  Red  Oak
Irrigated   with   Municipal   Wastewater.
Municipal  Wastewater  and  Sludge  through
Sopper,  W.E.   and  L.T.    Kardos,   (ed.).
Pennsylvania State University Press.   1973.
                                   and  B.E.    Cutter.
                                   and  ana  Red  Pine
                              In:    Recycling  Treated
                               Forest  and   Cropland.
                                University  Park,   The
                               pp  295-310.
                                  5-108

-------
87.  Alich, J.A., Jr.  and R.E.  Inman.  Effective Utilization  of  Solar
     Energy  to Produce a Clean Fuel.  Stanford Research Institute,  Menlo
     Park, Calif.  Project 2643.  Final Report.  June 1974.

88.  Spangler, F.L., W.E.   Sloey,  and  C.W.   Fetter,  Jr.   Wastewater
     Treatment   by   Natural   and  Artificial  Marshes,  University  of
     Wisconsin.  Oshkosh, Wisconsin.  EPA-600/2-76-207.  September 1976.

89.  Wolverton, B.C.  Water Hyacinths for Removal of Cadmium  and  Nickel
     from  Polluted  Waters.  NASA Technical Memorandum, TM-X-72721.  Bay
     St.  Louis, MI  February 1975.

90.  Wolverton, B.C.  and R.C.  McDonald.  Water Hyacinths for  Upgrading
     Sewage Lagoons to Meet Advanced Wastewater Treatment Standards, Part
     1.   NASA  Technical  Memorandum TM-X-72729.  Bay St.  Louis,  Miss.
     October 1975.

91.  Farnham, R.S.   and  D.H.   Boelter.   Minnesota's  Peat  Resources:
     Their  Characteristics and Use in Sewage Treatment, Agriculture, and
     Energy.  In:  Proceedings of the National Symposium  on   Freshwater
     Wetlands and Sewage Effluent Disposal.  University of Michigan.  Ann
     Arbor, May 1976.  pp 241-256.

92.  Morris, C.E.  and W.J.  Jewell.  Regulations and Guidelines for Land
     Application of Wastes.  In:  Land as a Waste Management Alternative.
     Loehr, R.C.  (ed.) Ann Arbor, Ann Arbor Science.  1977.  pp 63-78.

93.  Klausner,  S.D.   Crop  Selection   and   Management.    In:    Land
     Application  of Wastes - An Educational Program, Cornell University,
     May 1976.

94.  Christensen, L.A., L.J.   Conner,  and  L.W.   Liddy.   An  Economic
     Analysis  of  the  Utilization  of  Municipal  Waste  Water for Crop
     Production.  Department of Agricultural  Economics,  Michigan  State
     University,  East  Lansing.   Report  No.   292.   US  Department of
     Agriculture, Economic Research Service, Natural  Resource  Economics
     Division.  November 1975.  40 p.

95.  Seabrook,  B.L.   Land  Application  of  Wastewater  in   Australia.
     Environmental   Protection   Agency,   Office   of  Water  Programs.
     EPA-430/9-75-017.  May 1975.

96.  Parizek, R.R.  Site Selection Criteria  for  Wastewater  Disposal
     Soils  and  Hydrogeologic  Considerations.   In:   Recycling Treated
     Municipal  Wastewater  and  Sludge  through  Forest  and   Cropland.
     Sopper,  W.E.   and  L.T.   Kardos,  (ed.).   University  Park,  The
     Pennsylvania State University Press.  1973.  pp 95-147.

97.  Powell,  G.M.   Design  Seminar  for  Land  Treatment  of  Municipal
     Wastewater Effluents.  EPA Technology Transfer Program.   (Presented
     at  Technology Transfer Seminar.  1975.)  75 p.-
                                   5-109

-------
 93.    Blakeslee,  P.A.  Monitoring Considerations for Municipal  Wastewater
       Effluent  and  Sludge  Application to the Land.  In:  Proceedings of
       the  Joint Conference on Recycling Municipal Sludges and Effluents on
       Land,  Champaign, University of Illinois,  July 1973.  pp 183-198.

 99.    Branson, R.  L.   Soluble Salts, Exchangeable  Sodium,  and  Boron in
       Soils.    In:    Soil   and   Plant-Tissue  Testing  in  California.
       University   of  California,  Division  of   Agricultural   Sciences.
       Bulletin 1879.  April 1976.  pp 42-48.

100.    Walsh,  L.M.  and   J.D. Beaton,     (eds.).  Soil  Testing  and  Plant
       Analysis.   Madison, Soil Science Society of America.  1973.

101.    Melsted,    S.W.    Soil-Plant    Relationships    (Some    Practical
       Considerations  in Waste Management).  In:  Proceedings of the Joint
       Conference  on Recycling Municipal Sludges  and  Effluents  on  Land,
       Champaign,  Univeristy of Illinois,  July 1973.  pp 121-128.

102.    Land Leveling.  Irrigation, Chapter 11.   SCS  National   Engineering
       Handbook,    Section  15.   U.S.   Department  of  Agriculture,  Soil
       Conservation Service.  November 1961.
                                   5-110

-------
                                CHAPTER 6

                              SMALL SYSTEMS
6.1  General Considerations
According  to a 1973 survey, 54%, of the land treatment systems were less
than  1.0  Mgal/d  (43.8  L/s) LU.  While the design principles of land
treatment  are  the  same  for all sizes of systems,  the approach should
consider  a  system  that is compatible with community resources, design
and  operational  complexity,  and  possible  environmental  impact.   The
criteria  presented 'in this chapter are principally intended for systems
with a daily wastewater flow of 0.2 Mgal/d (8.8 L/s)  or less but in some
cases  may  be  used for intermediate systems with flows from 0.2 to 1.0
Mgal/d (8.8 to 43.8 L/s).  For treatment systems with flows  greater than
1.0  Mgal/d  (43.8  L/s),  the  additional  design  details  presented in
Chapter  5 should be considered.  Sources for cost data are  described in
Chapter 3.


Small  systems  generally  do  not have full-time operators, so a design
that  requires a few days of field operator time per  week or a few hours
each  day  is  desirable.  In recognition of this, a  small  system may be
designed  somewhat  conservatively, and hence should  be less affected by
climatic  and  wastewater  variations  than  larger systems.  Further,  a
conservative  approach to design is often necessary because  actual  field
data  can  be  quite limited.  If, for example, there is a range of soil
permeabilities,  the  lower  values  should be selected for  design.   The
capabilities  of  the  system  or  the  operators  will generally not be
sufficient  to  take  advantage  of  varying site conditions to minimize
costs.   The type of information typically required for the design  of  a
small system and sources of information are presented in Table 6-1.


6.2  Design Procedures


The  design  procedure for small systems follows a sequence of events as
presented  in  Figure  6-1.   The necessary information to complete each
step is presented in the following sections.


     6.2.1  Wastewater Characteristics and Flows
The determination of wastewater characteristics and flows is the initial
design step.  For existing treatment systems, the preferred method is to
measure  actual flows and.wastewater characteristics.  For systems under
planning   or   construction,   an   estimate  of  important  wastewater
characteristics  can  be  made  with  the aid of Table 6-2, using medium
strength  values for average domestic/commercial conditions.  The strong
                                  6-1

-------
values   would   apply   for  new systems with  low water use  and some minor
industrial   wastewater    contributions.   Weak  values  would  be   more
applicable to  systems  where an older collection system with  little or no
industrial  wastewaters  and where  infiltrating water results in dilution
of the  wastewater strength.
                                    TABLE  6-1

                   TYPES AND  SOURCES OF  DATA REQUIRED FOR
                            LAND TREATMENT DESIGNS
                   Type of data
       Principal  source
              Wastewater data

              Soil type and permeability

              Temperature (mean monthly
              and growing season)

              Precipitation (mean
              monthly, maximum monthly)

              Evapotranspiration and
              evaporation (mean monthly)


              Land use
              Zoning
              Agricultural  practices
              Surface and groundwater
              discharge requirements

              Groundwater (depth
              and quality)
Local wastewater authorities

SCS soil survey

SCS soil survey, NOAA, local
airports, newspapers

SCS soil survey, NOAA, local
airports, newspapers

SCS soil survey, NOAA, local
airports, newspapers, agricultural
extension service

SCS soil survey, aerial photos from
the Agricultural Stabilization and
Conservation Service, and county
assessors' plats

Community planning agency, city or
county zoning maps

SCS soil survey, agricultural
extension service, county agents

State or EPA
State water agency, USGS, driller's
logs of nearby wells
 Another   source of  dilution  may be  cooling waters and  other  low strength
 discharges  from  local industries.   Special attention  should be given  to
 wastewater  from   nonhousehold  sources  that   may   contain  constituents
 significantly  different   than  those in Table 6-2.  Characterization  of
 nonhousehold wastewater should be made from field sampling,  measurements
 at  existing  facilities,  at  some  other  similar  facility,   or   from
 published  values  L.2].    Significant amounts  of nonhousehold wastewater
 may  require  additional   design  consideration  from  that given in  this
 chapter.
                                       6-2

-------
                                                                  FIGURE  6-1
                                                       SMALL SYSTEM DESIGN  PROCEDURE
I
co
CHARACTERIZE
 WASTEWATER
 QUALITY  &

  QUANTITY

   6.2.1
                                               DETERMINE

                                              SURFACE AND

                                              GROUNDWATER
                                               DISCHARGE
                                              REQUIREMENTS
  LOCATE
AVAILABLE
  SITES

  6.2.2.
                                             CHARACTERIZE

                                              SITES BASED
                                             ON SOILS AND
                                            OTHER FEATURES

                                                6.2.3
EVALUATE AND
SELECT UNIT
PROCESS AND
CORRESPONDING
APPLICATION
    AREA
   6.2.4
  DETERMINE
PREAPPLICATIQN
  TREATMENT
 STORAGE AND
  METHOD OF
  APPLICATION
    6.2.5
    6.2.6
    6.2.7
FACILITIES

  DESIGN

   6.3

-------
                                 TABLE 6-2

              IMPORTANT  COMPONENTS OF DOMESTIC WASTEWATER  [3J
                                   mg/L
                                        Concentration

                                     Strong Medium Weak
                       BOD5, 20°C         300   200   TOO

                       Suspended solids    350   200   TOO

                       Nitrogen as N

                         Organic          35    15     8
                         Free ammonia       50    25    12
                         Nitrates          _0    _0    _0

                          Total          85    40    20

                       Phosphorus as P

                         Organic          532
                         Inorganic         15     7     4

                          Total          20    10     6
The annual volume  of  wastewater will  be used to estimate the  application
area.   Due  to  the extremely variable nature, wastewater flows  are  best
determined from  field measurement.   In cases where this is  not possible,
an  estimate  can  be  made  from  available  data using a  per capita or
fixture  basis   |_4].    The  per  capita  basis  is  generally preferred.
Typical  flows from recreational  facilities and institutional facilities
are  presented   in Tables 6-3 and  6-4.  A common value used  to  estimate
daily  wastewater  flows   is 75 gal/capita (284 L/capita) with a peaking
factor of 4.0 for  the peak flow L5J.   Seasonal variations in  flow should
be  considered   in the  estimate  of  annual  wastewater   volume and in
discharge requirements.


     6.2.2  Locate Available Sites
Identification   of   sites  for  small   systems  is  usually  much   less
complicated  than  that  for  larger  systems.  The search begins at the
point  of  wastewater  collection and radiates outward until  one or  more
potentially  suitable  sites  have  been  located.   These  sites may be
identified by the  following desirable features:

     1.   Fairly   large  tracts  of  undeveloped  land  or farms under a
          single ownership.

     2.   Land  that  is  now or has been farmed, or is forested.
                                   6-4

-------
                           TABLE 6-3

         DESIGN  UNIT  WASTEWATER FLOWS FOR RECREATIONAL
           FACILITIES,  YELLOWSTONE NATIONAL PARK [3]
Establishment
Campground (developed)
Lodge or cabins
Hotel
Trailer village
Dormitory, bunkhouse
Residence homes, apartments
Mess hall
Offices and stores
Visitor centers
Cafeteria
Dining room
Coffee shop
Cocktail lounge
Laundromat
Gas station
Fish-cleaning station
Unit
Person
Person
Person
Person
Person
Person
Person
Employee
Visitor
Table seat
Table seat
Counter seat
Seat
Washing machine
Station
Station
Unit flow, gal/d
25
50
75
35
50
75
15
25
5
150
150
250
20
500
2 000-5 000
7 500
                            TABLE  6-4

                 AVERAGE WASTEWATER FLOWS  FROM
                 INSTITUTIONAL FACILITIES  L3J
Institution
Medical hospital
Mental hospital
Prisons
High schools
Elementary schools
Avg flow, gal /capita
175
125
175
20
10
                 1 gal/capita = 3.78 L/capita
3.   Location is relatively near point of wastewater collection.

4.   Groundwater is more than 10 ft  (3 m) deep  or  there  is  a  nearby
     water  body  that  could  be used to receive  the underdrainage
     needed  to lower the water table and to  receive the percolated
     effluent.
                              6-5

-------
     5.   Land  that  is  already  for  sale  or  that can be bought with
          reasonable negotiations.

     6.   Zoning  that  is  compatible  with  land  treatment facilities
          requirements, such as areas zoned for greenbelts.

     7.   Existing  irrigated  lands (e.g., golf  courses, parks,  highway
          landscaping).

     8.   Access from developed roads and power supply.
At  this  point  in  the  site investigations neither the land treatment
process nor the total land area is known.   In order to make some initial
assessment  of  the  sites, some preliminary estimate of area is needed.
Guidelines  to  land  area needs for preliminary  site identification are
provided in Table 6-5.  These values are for screening purposes only and
must be refined as the study progresses.
                                TABLE 6-5

                     TOTAL LAND AREA GUIDELINES FOR
                     PRELIMINARY SITE IDENTIFICATION
                                     Land area, acres
                         Slow rate
Rapid infiltration  Overland flow
flow, gal/d
100 000
200 000
300 000
500 000
750 000
1 000.000
6 mo/yr
15-30
30-50
40-80
60-150
100-200
150-300
12 mo/yr
7.5-20
15-40
20-60
30-100
50-150
75-200
12 mo/yr
0.5-6
1-12
1.5-20
2.5-30
4-45
5-60
10.5 mo/yr
3-10
5-20
10-30
15-50
25-75
35-100
           100 000 gal/d = 4.38 L/s
           1 acre = 0.405 ha
     6.2.3  Site Characterization
Having   identified    the    potential    sites,    the  next  step  is  to
systematically describe  the  site  characteristics.   These characteristics
and  the  required effluent  quality  requirements  will  combine to suggest
the type of land  treatment process that  should  be.used.
                                   6-6

-------
Site characteristics that should be noted Include the following:

     1    Soils—type,  distribution^  permeability  of most restrictive
          layers,  physical   and  chemical  characteristics, and depth to
          groundwater

     2.   Available land area, both gross and net areas (i.e.,  excluding
          roads,  rights-of-way   encroachments,   stream  channels,   and
          unusable soils)

     3.   Distance   from   source  of  wastewater  to  site,   including
          elevation differential

     4.   Topography, including relief and slopes

     5.   Proximity  of  site  to  industrial,  commercial,  residential
          developments;  surface  water  streams;  potable  water wells;
          public  use  areas  such  as  parks,  cemeteries,  or wildlife
          sanctuaries

     6.   Present and future land uses

     7.   Present vegetative cover
     6.2.4  Select Land Treatment Process
The  selection  of the appropriate unit process depends primarily on the
following two conditions:

     1.   Soil characteristics at the prospective site

     2.   The  requirements  of  the  discharge  permit  or  groundwater
          quality


Obviously,  other  conditions  such  as  other site features, total  land
area,  operating  personnel,  and  related  economic  and  environmental
factors,  combine  to help form the final conclusion.  A decision matrix
for  forming preliminary conclusions on the land treatment process based
on  technical  considerations  only  is  presented  in Table 6-6.  Other
related conditions can then be used to finalize the decision.
The  preferred  land  treatment options for small systems are, in order:
slow  rate,  rapid  infiltration,  and  overland  flow.  Other treatment
processes   have   been   used  to  treat  wastewater  in  research  and
demonstration  projects but applicable design criteria are not generally
available.  Slow rate systems are the first design choice because of the
similarity  to  normal  agricultural practices, and their performance is
the least sensitive to operational changes so that treatment reliability
under  variable  conditions is greatest.  Rapid infiltration systems are
                                  6-7

-------
                                 TABLE 6-6

                      PRELIMINARY  SELECTION OF LAND
                            TREATMENT SYSTEMS
   Levels of effluent
    quality (NPDES
    permit), mg/L
                Range of soil permeability, in./h
     iBOD = 10
     *SS  = 10
     *N   =3
     £P   =5

     No surface
     discharge3
 <0.06
       0.06-0.2  0.2-0.6   0.6-2.0   2.0-6.0
                                        6.0-20.0
                                                  >20.0
SBOD = 4
*ss = 2
iN 4
SP 0.1
SBOD 5
SSS 5
iN 15
iP 1
	 Slow rate Slow rate Slow rate Slow rate
	 Rapid
infiltration

Rapid Rapid
infiltration infiltration
Overland  Overland
flow    flow
       Slow rate Slow rate  Slow rate Slow rate
                                       Slow rate
                                                Slow rate
                                               Rapid      Rapid      Rapid
                                               Infiltration Infiltration  Infiltration
   a.  Discharge to groundwater or indirect discharge to surface water.

   1 in./h = 2.54 cm/h
the  second  choice  in   small   scale  systems   because removals  of most
wastewater  components  are  excellent with low  operation and maintenance
requirements.    A consistent level  of nitrogen  removal, however,  is more
difficult  to  obtain  than   with  other  systems.    In some groundwater
aquifers   nitrogen  content   is of little concern,  greatly enhancing the
use  of   rapid  infiltration systems.  Overland flow systems require the
greatest   level   of  on-site  management  to  maintain  high   levels  of
treatment  so  extra  operator  training  is  required, particularly for
proper maintenance of the terraces.


After  selecting  the unit process, the required "wetted" or application
land  area  can  be  computed.    In  general,   this calculation  requires
development  of  the  hydraulic  application  rate  and  the duration of
application  during  the   year.    It  also   requires  consideration  of
additional  applied water  in  the form of precipitation and the  lost water
due  to percolation and evapotranspiration.   This computation  is  usually
combined   with  a  water   balance  computation   for  determining  storage
requirements.    For  each treatment  system  this procedure is  somewhat
different.    Therefore,   computations  of wetted land area are discussed
separately for each process  and summarized in Table 6-7.
                                     6-8

-------
                                     TABLE 6-7

        SUMMARY OF  APPLICATION PERIODS FOR  LAND TREATMENT  SYSTEMS
Unit process

management
Appl ication
Description Estimated period
         Slow rate     Annual crop    Growing season only        3-5 months

                     Double crop    All year unless restricted  6-12 months3 (also
                     or perennials  by weather or planting    • see Figure 6-2)
                                  and harvesting
         Rapid        NA
         infiltration
         Overland
         flow
     Perennial
     grasses
All year-round, if in free 12 months
draining materials

All year unless restricted See Figure 6-2
by weather
         NA = not applicable.

         a.  This period is maximum in semiarid areas.  The lower values should
            be used where winters are severe.
            6.2.4.1   Application Area  For Slow Rate  Systems
The   application   area
application   rate   and
permeability
determine  a
requirements
Table 6-8.
            for  slow   rate   systems   is  based  on a  weekly
            the  length  of   the  application   season.    The
of  the predominant soil  types  combined with  crop water use
weekly application rate, as  shown in  Table 6-8.   Water use
of  most   crops  will   be met  using  the rates presented in
                                    TABLE  6-8

                 DESIGN  APPLICATION RATES FOR SMALL SYSTEMS
Application rate, in./wk
SCS permeability
class
Very slow
Slow
Moderately slow
Moderate
Moderately rapid
Rapid
Very rapid
SCS permeability
range, in./h
<0.06
0.06-0.2
0.2-0.6
0.6-2.0
2.0-6.0
6.0-20
>20
Slow rate3

0.5-1.0
1.0-1.5
1.5-3.0
3.0-4.0
4.0

a. Application during growing season.
b. Year-round application
c. Volume applied equally during 5 to. 7 days pe
Rapid Overland
infiltration'' flowc


4-20
8-30
12-40

r week; low value
4-8
4-8





for
             screened effluent and higher rates for primary and biological treat-
             ment effluent.

          1  in./wk = 2.54 cm/wk
                                      6-9

-------
The  length of the application season should be computed on the basis of
intended management.  Two management techniques are commonly practiced:

     1.   Grow a single, annual  crop

     2.   Grow  perennial  forage  grasses,  practice double-cropping, or
          use the no- till management system


For  a  single  annual  crop, the application period will  be the growing
season plus any preplanting or after harvest irrigation and could result
in  an  application  period  as short as 3 months.   For this reason,  the
second management technique is generally used.


For  the second case, the application season is determined from climatic
data  given  in  a  county  soil   survey or other local source, for  the
proposed vegetation.  The mean growing season,  i.e., the number of weeks
between  the last 32UF (0"C) occurrence in the spring and the first 32°F
(0UC)  occurrence  in  the  fall, is used for all  annual crops.  Typical
annual  crops  used in the United States with land treatment systems  are
corn,  wheat,  barley,  cotton,  and soybeans.  To  extend the application
period for annual crops, they may be double-cropped, or winter or spring
cover  crops  may  be  planted  after  harvesting.    Perennial  crops  are
typically  forage  grasses  such  as  Bermuda grass, orchard grass, tall
fescue,  Reed  canary  grass,  and  alfalfa.   Wastewater can be applied
between  occurrences  of  26°F  (-3.3°C) temperatures in the spring  and
fall.   The  application  period  should be reduced by 30 to 45 days to
allow  for  planting  (annual  crops  only)  and harvesting periods.  The
annual  application volume is determined by  multiplying the weekly rates
from  Table  6-8  by the length of the application season in weeks.  The
annual   application  rate  determines  the   required  application area
according to the following equation:
where  F =     field area, acres (ha) 3
       Q =     annual flow, Mgal/yr (m /yr)
       L =     period of application wk/yr
       R =     rate of application, in./wk (cm/wk)

      36.8  (0.01)  =  conversion  factor =  3.06  a^re7ft x 12 in'
                                                   Mgal    n   ft
                                  6-10

-------
          6.2.4.2  Application Area For Rapid Infiltration Systems


Where application of wastewater to an infiltration basin is by flooding,
the  period  of  application is the entire year.   An exception may  occur
under one of the following conditions:

     1.   The  soil is fine textured or not free  draining so freezing of
          water within the soil pores renders it  impermeable.

     2.   The  water  is  applied by sprinkler methods,  and the droplets
          freeze and coat the surface with ice.

     3.   There  is  a  severe  low temperature resulting in freezing of
          water in the distribution piping or as  it exits.


Although some provision is recommended for storage to account for one of
the  above  events,  the application period can be assumed as 12 months.
The  application  rate  can  be  selected  from  Table 6-8 based on soil
permeability.   Then, using Equation 6-1 and an application period of 52
weeks, the application area can be computed.


          6.2.4.3  Application Area For Overland  Flow Systems


This  process  requires  an effluent discharge to either a surface water
body  or  another unit process.  Consequently, application rates are not
dependent  on  soil  permeability  but  rather  on  biological activity.
Experience has indicated that an application rate of 4 in./wk (10 cm/wk)
will easily match biological activity on the prepared slopes.


The  application  period  is  usually.determined  by climatic conditions.
These  conditions  are  similar to those for perennial grasses with slow
rate systems.  In general, Figure 6-2 can be used to estimate the number
of  days  that overland flow cannot operate.  Subtracting this period in
weeks  from  52  wk/yr  will  result  in  the application period.  Using
Equation 6-1, the wetted area can be computed.


     6.2.5  Preapplication Treatment


Preapplication treatment is desirable for small scale systems to control
nuisance  and odor conditions during storage with slow rate and overland
flow  systems,  and  to  lessen  bed  maintenance  on rapid infiltration
systems.  Biological treatment is often employed  with many forms of land
treatment   but  may  be  avoided  with  overland   flow.   Also,  rapid
infiltration  may  be  used  with  only  primary  level treatment but the
application  rate  must be reduced somewhat over  that of secondary level
because  of the clogging effect of suspended solids.  The use of primary
                                  6-11

-------
                                    FIGURE  6-2
   ESTIMATED WASTEWATER  STORAGE  DAYS BASED ONLY  ON CLIMATIC FACTORS [6]
SHADING  DENOTES REGIONS  WHERE
THE  PRINCIPAL CLIMATIC CONSTRAINT
TO APPLICATION OF WASTEWATER
IS PROLONGED WET SPELLS
                                                                               i eo
                                                                           BASED ON 32°F  (0°C)
                                                                           MEAN TEMPERATURE
                                                                           0.5 in./d  PRECIPITATION,
                                                                           t in.  OF SNOWCOVER
1  i n.= 2.54 en

-------
effluent is recommended, but if  land area is limited it may  be  necessary
to  provide  a  higher  level  of  preapplication  treatment.   A  suggested
guide   to the selection of preapplication treatment levels for  each land
treatment process  is  presented in  Table 6-9.
                                  TABLE 6-9

                 MINIMUM PREAPPLICATION TREATMENT  PRACTICE
                          Process
       Preapplication treatment
                   Slow rate

                     Surface application
                     Sprinkler application

                   Rapid infiltration

                   Overland flow
        Primary sedimentation

        Primary or biological3

        Primary

        Bar screens and
        comminution
                   a.  Typically oxidation ponds or aerated lagoons.
     6.2.6  Storage  Requirements
Storage   volume  estimates must  include consideration of the  total  water
balance   for  the  year.    However,   the  designer  can approximate this
storage   by  referring to Figure 6-2  and selecting the proper values for
the geographical location in question.   The values taken from the figure
represent days of  storage for the  worst year  in  20, based on  severity of
winter conditions.   Storage requirements may  be  further reduced by  sea-
sonal discharges to  surface waters if permitted  by  the  state.   Storage
volume guidelines  are summarized in  Table 6-10.
                                 TABLE  6-10

                       GUIDELINES FOR  STORAGE VOLUMES
                  Land treatment
                    process
    Storage volume guidelines
                Slow rate

                  Annual crops

                  Perennial crops

                Rapid infiltration

                Overland flow
Up to 9 months of flow

0.5-6 months of flow, see Figure 6-2

7-30 days of flow

See Figure 6-2
                                    6-13

-------
     6.2.7  Selection of Application  Systems
In  preliminary  design  for slow rate,  the method of  applying  the water
must  be  decided.   Surface  application  is   preferred  where the  site
topography  is  quite flat or is suitable for  application with  a minimum
amount of leveling.  This method of application offers the least capital
cost  and  the  least  operation  and maintenance cost for most systems.
Also,  there  should  be  no problems with aerosol  transport or need for
buffer zones.
Sprinkler  application  may  be  used  for   almost  any   topography,  but
preferably  one  having slopes of less than  15%  to minimize  difficulties
with effluent runoff and erosion control.  For small  systems,  the  use of
surface application systems is preferred for both  rapid  infiltration  and
overland flow treatment.
     6.2.8  Postapplication Treatment


In  those  cases  where  effluent  is collected  for discharge  to  surface
waters,  discharge requirements must be met.   Systems  with  overland  flow
may  require  postdisinfection:   Disinfection may be  accomplished using
hypochlorinators   or,   in  some  cases,   an  erosion  feeder type  of
chlorinator may be used.  The latter units  have  not been widely accepted
but may offer suitable reliability for very small  systems.


6.3  Facilities Design


As in other parts of this manual, no attempt will  be made to discuss the
detailed design of preapplication treatment and  storage  facilities.   The
discussion  is  limited to the distribution and  application systems.   In
addition  to  the  comments  contained  in   this  chapter,  the reader is
directed  to Section 5.8 for detailed design guidance.   Distribution and
application systems will be discussed for each land treatment  process in
the following section.
     6.3.1  Slow Rate System
A  schematic  diagram showing the typical  elements of a slow rate  system
is presented in Figure 6-3.


          6.3.1.1  Surface Application Systems


Surface   application   systems   require   site-specific  design,   while
sprinkler  system  design  should  be  based  on  consultation  with  the
                                   6-14

-------
                                                         FIGURE 6-3

                                              SCHEMATIC FOR TYPICAL SLOW RATE SYSTEM
0>
I
                PRELIMINARY
                 SCREENING
PREAPPLI-
CATION
TREATMENT
                                                      STORAGE
                                                                                              SURFACE APPLICATION
                                                                                           TO  GROUNDWATER  OR RECOVERY
                                                                                    I
    ALTE.RNATIVE
    DISTRIBUTION
r   SYSTEMS
                                                                     DISINFECTION
                                                 I
                                                                                            SPRINKLER  APPLICATION
                                                                                    L	.
                                                                                                    &%
                                                                                                             A
                                                                                                 \   rtK/F|I

                                                                                                   I     I    I
                                                                                           TO GROUNDWATER OR RECOVERY

-------
equipment  manufacturers.    The  general  factors   involved in the final
layout and design  of a surface application system  are  presented in Table
6-11.   Most   of   the  common surface irrigation systems are included in
this table.
                                TABLE 6-11

                  FACTORS AFFECTING THE DESIGN OF SURFACE
                          IRRIGATION SYSTEMS [7]
Maximum




Level
Level border
Contour levee
Level furrow

Graded
Graded border
Contour ditch
Graded furrow

Corrugation
Contour furrow

Humi d


Nonsod
crops

Nearly
0.1
Nearly


0.5
NA
0.5

NA

areas

crops

level
0.1
level


2.0
4.0
NA

NA
Cross slope
3.0
3.0
slope.
Arid


Nonsod
crops

Nearly
0.1
Nearly


2.0
4.0
3.0

4.0
Cross
6.0
u.»__ . — I*..*; —

a reas

crops

level
0.1
level


4.0
15.0
NA

8.0
slope
6.0
ouc OHplllal.luH
family •- /k3

Mi n i mum

0.1
0.1
0.1


0.3
0.1
0.1

0.1
0.1



T ^
Maximum

2
0
2


2.
3.
3

1
2,


.0
.5
.0


.0
.0
.0

.5
.0

Shape of field

Any shape
Any shape
Rows should be
of equal length

Rectangular
Any shape
Rows should be
of equal length
Rectangular
Rows should be
of equal length
\ 1 uw Ul
bedded)

Yes
Yes
Yes


No
No
Yes

No
Yes


p tab e
. .
i o ,, urcnaras
or sodded ~~
crops

Yes
Yes
Yes


Yes
Yes
Yes

Yes
No

fliiu
vineyards

Yes
Yes
Yes


Yes
Yes
Yes

Yes
Yes

   NA = not applicable.

   a. Intake family is a grouping of soil by the SCS.  It is based on the ability of the soil to take in the required
     amount of water during the time 1t takes to irrigate.

   1 in./h = 2.54 cm/h
The  most  desirable design is one  in which  the furrows or border checks
are  so   flat  that  failure to rotate  the flow to the next field in  the
system  would  not result in wastewater escaping the property.-  In  other
words,   the  field  would  be  flat enough   to  permit  an enclosing or
containment  levee  around the field.   Alternative choices are tailwater
control   systems  or  a gravity return  to  the lagoon at the lower end of
the  site.   If this is not possible, closer supervision of the operation
will be  necessary to minimize the risk  of  nuisance conditions occurring.


Any  of   the  common low head or gravity design pipe materials should be
suitable  for  transporting the wastewater to the field.  Gated aluminum
pipe is  an effective means of distributing the water uniformly to border
checks  or furrows.  Open concrete  lined ditches with turnouts have been
used effectively with small systems.
                                   6-16

-------
          6.3.1.2  Sprinkler Application Systems


If  a sprinkler irrigation system has been selected,  the designer should
work  closely with one or more sprinkler manufacturer's vendors who  will
aid  the  designer  in  the  use  of  their  respective  equipment.   The
availability  of  a knowledgeable local  representative may weigh heavily
in the final selection of equipment.


A  list of most of the common types of sprinkler systems, guidelines for
their   application,  and  limitations  is  presented  in   Table 6-12.
Additionally,   some   states   have   published  regulations  regarding
preapplication disinfection, minimum buffer areas,  and control  of public
access  for  sprinkler  systems.   These criteria should be reviewed for
applicability.


Distribution  systems  may  consist  of  any of the common pressure  pipe
materials, such  as plastic, aluminum, asbestos-cement, tlined and coated
steel, or ductile iron.
The final design analysis should consider the following points:

     1.   Provision of adequate thrust blocks

     2.   Consideration of water hammer and surge conditions

     3.   Winter operation criteria

     4.   Provisions  of  sufficient  valves  and  manifolding to permit
          proper agricultural management of the field

     5.   Automatic timers to limit the application in any one area

     6.   Alarms to signal system failures

     7.   Protection against plugging by algae


     6.3.2  Rapid Infiltration Systems


Small  scale  rapid  infiltration  systems  typically  apply  an  annual
application of 17 to 173 ft (5 to 53 m) of wastewater at rates of 4.0 to
40.0  in./wk (10 to 100 cm/wk).  The application rate is determined from
soil  permeability  data.  It is preferable to dig at least one test pit
(see  Appendix F) and conduct three infiltration tests (see Appendix C).
Multiple   infiltration  basins  are  required  to  permit  intermittent
application.    A  desirable  basin  design  should  provide  sufficient
flexibility to permit a 1 to 4 day application period followed by a 7 to
14 day drying period.
                                  6-17

-------
en

«l
CO
                                                             TABLE  6-12

                                FACTORS AFFECTING THE DESIGN OF SPRINKLER IRRIGATION SYSTEMS  [7]
System
Multisprinkler
Hand moved
Portable set '
Solid set
Tractor moved
Skid mounted
Wheel mounted
Sel f moved
Side wheel roll
Side move
Self propelled
Center pivot
Side move
Single sprinkler
Hand moved
Tractor moved
.Skid mounted
Wheel mounted
Self propelled
Boom sprinkler
Tractor moved
Self propelled
Permanent
Maximum
slope, %

20
2.0
5-10
5-10
5-10
5-10
5-15
5-15

20
5-15
5-15
No limit

5
5
No limit
Water application
rate, in./h
Minimum

0.10
0.05
0.10
0.10
0.10
0.10
0.20
0.20

0.25
0.25
0.25
0.25

0.25
0.25
0.05
Maximum

2.0
2.0
2.0
2.0
2.0
2.0
1.0
1.0

2.0
2.0
2.0
1.0

1.0
1.0
2.0
Shape of field

Rectangular
Any shape
Rectangular
Rectangular
Rectangular
Rectangular
Circular
Square or
rectangular

Any shape
Any shape
Any shape
Rectangular

Any shape
Rectangular
Any shape
Field surface
conditions

No limit
No limit
Smooth enough for
safe tractor operation
Reasonably
smooth
Clear of obstructions,
path for towers

No limit
Safe operation
of tractor
Land for winch
and hose

Safe operation
of tractor
Lane for boom and hose
No limit
Maximum
height of
crop, ft

No limit
No limit
No limit
No limit
4
4-6
8-10
8-10

No limit
No limit
No limit
No limit

8-10
8-10
No limit
Size of
single
system, acres

1-40
1 +
20-40
20-40
20-80
20-80
40-160
80-160

20-40
20-40
20-40
40-100

20-40
40-100
1+
                       1 in./h = 2.54 cm/h
                       1 ft = 0.305 m
                       1 acre = 0.405 ha

-------
 A  typical  rapid infiltration system is illustrated  in Figure 6-4.  The
 layout  is  based  on  a  relatively  level land surface.  Sloping lands
 should  utilize  gravity  flow  to  minimize pumping  costs.  Site layout
 should  locate  the  maximum  bed  dimension  perpendicular  to probable
 groundwater flow.  Steeper land would require smaller basins to minimize
 cut  and  fill  and  to  avoid  cross-basin  subflows according  to the
 following  schedule:   for  0  to 1% average cross-slope--! basin; 2%—Z
 basins;  3%--4  basins.  Slopes in excess of 3% should be graded to a 3%
 average before final basin construction.
                                FIGURE 6-4

                          SCHEMATIC FOR TYPICAL
                        RAPID INFILTRATION SYSTEM
              CONTAINMENT BERN
                                       PREAPPLICATION
                                       TREATMENT
                                             EMERGENCY
                                             STORAGE
                                          SPLASH APRONS

                                             #4
                                                         INFILTRATION
                                                         BASINS
Surface  design  details   related   to  infiltration  basins  are similar to
those  for  sludge  drying beds with care  being  taken  to minimize  severe
erosion  at the point of  application.  Provision for access  to the basin
should  be included to permit entry of a tractor with  a disk,  harrow,  or
other  scarifying   equipment.   The   need  for   underdrains  should   be
determined  based  on Appendix C and details for design are  presented in
Chapter 5 (Sections 5.5.2  and 5.8).
                                  6-19

-------
     6.3.3  Overland Flow System
Although  the preferred method of applying  wastewater to the field is  by
surface  method,  many industrial  installations  now exist with  sprinkler
systems.  The typical  overland flow system, with alternative application
systems  is illustrated in Figure 6-5.   To  provide the maximum  treatment
efficiency,  wastewater  must  be  applied   at  least  once a day  and  in
sufficient quantity to wet the entire terrace  area.
A  suggested method of supporting distribution  piping is shown in Figure
6-6.  In this case, the stone serves as a support,  but it also serves as
a means to convert a point discharge into sheet flow, minimizing erosion
and maximizing treatment efficiency.
Where  sprinklers  are  used,  they  should be  placed downslope from the
highest  point  on  the  terrace  a  distance equal  to the radius of the
sprinkler, unless one-half circle sprinklers are  used.
Probably  the  most important feature of the overland flow system is the
sloped  terrace.   This slope must be as nearly  equal  to a plane surface
as  possible  and sloped in such a way as to prevent short-circuiting of
the wastewater and standing water in the collection ditches.   No swales,
depressions, or gullies can be permitted; otherwise, water will  pond and
permit propagation of mosquitos or the production of odors.


The second factor is the cover crop.  Grasses must be selected for their
resistance  to  continuously  wet  root  conditions.  Also,  their growth
should not be in clumps as this will result in the formation of rivulets
of  flow  rather  than  a  uniform  sheet flow.   Common grasses for this
purpose  have been Reed canary grass, Italian rye, red top,  tall fescue,
and Bermuda grass.
The distribution system should be designed to permit application on each
portion  of  the field for from 6 to 12 h/d.   This application period is
based on convenience rather than for treatment reasons.   The system must
be  valved  and  manifolded to permit a portion of the field to be taken
out  of service for grass mowing and/or harvesting.   During that period,
the  remainder  of the field must take the total  flow or else it must be
diverted  to  temporary  storage.   Following  prolonged  shutdown,  the
wastewater collected in the drainage ditches  may have to be recirculated
through  the  treatment  system  until  discharge requirements are again
being  met.   This  would  only  be  required  where stringent discharge
requirements are imposed.


Site  access  requires  special  equipment  with  broad tires having low
pressure  (less  than  10  lb/in.2  or 7 N/cm2)  to  avoid creating ruts
                                  6-20

-------
                                           FIGURE 6-5
                           SCHEMATIC FOR TYPICAL OVERLAND FLOW SYSTEM
                                             PROVIDE  FOR  RECIRCUUTION  OF  EFFLUENT
PRELIMINARY
 SCREENING
PREAPPLI-
CATION
TREATMENT
                                                  FOLLOWING  PROLONGED  SHUTDOWN
                                      STORAGE
                                                                           SURFACE  APPLICATION


                                                                          J™kJUU1^^
DISTRI-
BUTION
PUMPING
ALTERNATIVE
DISTRIBUTION
SYSTEMS
                                                                                         COLLECTION.
                                                                                         DISINFECTION
                                                                                         (IF REQUIRED)
                                                                                         AND DISCHARGE
                                                                             LOW PRESSURE
                                                                         SPRINKLER  APPLICATION
                                                                                         COLLECTION.
                                                                                         DISINFECTION
                                                                                         (IF REQUIRED)
                                                                                         AND DISCHARGE

-------
that would short-circuit the flow and  the treatment process.   Vegetation
harvest  and removal  is  not always necessary, since the vegetation can  be
cut  with   a  chopping  mower just prior to maturity (every  4 to 6 weeks)
and allowed to decompose on the terrace [8].  Applications  should be re-
duced  for  3 or 4 days after winter  shutdowns.

                                FIGURE 6-6

                       BUBBLING ORIFICE DISTRIBUTION
                             FOR OVERLAND FLOW
                                  3/4 in.  OUTLETS AT  4 FOOT SPACING
                                 ROTATE OR TWIST  PIPE  TO  ADJUST FLOW DISTRIBUTION)
                                       in. DIAMETER PIPE
                                           LOCALLY AVAILABLE CRUSHED  STONE

                                           5/8  in. TO 1  1/2 in. GRADATION
 DO«H SLOPE
 SHEET FLOW
   NOTE: 1
         1
i n.= 2.54cm
ft  =0.305 m
 6.4  Small  System Design  Example*
      6.4.1   Setting


 The  community  of  Angus,  Washington,  has decided to construct a  land
 treatment   system  to  meet its wastewater discharge specifications.  The
 following  information  is known:

            Present (1977) population - 2 234
            Projected 1997 population - 3 400
            Annual rainfall  - 48  in. (120 cm), evenly distributed throughout the year
            Warm season evaporation - 24 in. (60 cm), May 1  to October 1
            Seasonal flow variations -
             Maximum month  (August) - 1.5  of average
             Minimum month  (January) - 0.8 of average
 *Note:   This is an example;  it  is intended  for illustration only.
                                      6-22

-------
There is  an  elementary  school  of about 200 pupils and 15 staff.   The
high school is located in Hereford, about 10 miles (16 km) to the south.
There  are some small commercial establishments such as service stations
and  restaurants  but  the  town's  only industry, a sawmill, treats and
recycles  its  own  wastewater.   As  the  town  is presently sewered by
individual systems, mostly septic tanks, a new collection system will be
constructed.   Water  service  is unmetered and estimated consumption is
100 gal/capita-d (378 L/capita-d).


     6.4.2  Wastewater Quality and Quantity


Assume:   1.   Design for 1997 population
          2.   Projected pupil and staff population will be 325
          3.   Due  to  unmetered water system, waste is relatively  high
               and the wastewater will be of medium strength through the
               planning period (BOD = 200 mg/L).


Wastewater  quality  can  be  found  in  Table  6-2, second column.   The
flowrate  for  average  design  conditions,  using  an  estimated  daily
wastewater flow of 75 gal/capita (284 L/capita), is calculated to be:

            325 (10) gal/capita-d + 3 400 (75) gal/capita-d
                      = 258 250  say 260 000 gal/d


     6.4.3  Locate Available Sites


By  interpolation  of  the values in Table 6-5 for a flowrate of 260 000
gal/d the following preliminary site areas were determined:

     •    Slow rate, 26 to 52 acres (10.5 to 21 ha)

     •    Rapid infiltration, 3 to 13 acres (1.2 to 5.3 ha)

     •    Overland flow, 9 to 27 acres (3.6 to 10.9 ha)
As there is sufficient open space and farmland in the immediate area, it
was  decided  to  limit  the search for available sites to a radius of 1
mile (1.6 km) from the lowest point in the collection system to minimize
transmission costs.
     6.4.4  Site Characterization
After the search, four potential tracts were located, all about 0.5 mile
(0.8  km)  from  the designated point.  The characteristics of the sites
are summarized in Table~~-6-13.
                                  6-23

-------
                                 TABLE 6-13

           POTENTIAL LAND TREATMENT SITES FOR ANGUS, WASHINGTON
                                          Range of soil     Slope,
     Site No. of           Size,   Minimum depth to  permeabilities,   average-
      No, owners  Current use3 acresb  groundwater, ftc    in./hd    maximum, %d
                       Remarks
A
B
C
D
5 Agriculture
1 Undeveloped
land
1 Nonirrigated
pasture
2 Low density
housing
200
95
300
30
15
10
20
10
0.6-20
0.2-2.0
0.06-0.5
0.2-0.6
2-10
Flat
5-15
4-5
15 acres at
5-10 in./h
Potential
greenbelt
Low permeability
results in local
wet spots
One house zoned
residential
     Sources:  a.  Local planning agency and site visit.
            b.  County assessor.
            c.  Well logs.
            d.  SCS report.
     1 acre = 0.405 ha
     1 ft = 0.305 m
     1 in. = 2.54 cm


On the  basis of acreage requirements, all sites  except Site D would have
sufficient  acreage for all  systems.   Site D would be marginal for a slow
rate  system and would require  additional soil testing if it is  found to
be the  most desirable location.
Sites  A,   B,   and  C  appear  to have area in excess of the anticipated
needs.   The  treatment  site  and facilities could be located in  the most
desirable  location within  the site and not all of the land would have to
be purchased.
     6.4.5   Select Land Treatment Process
Discharge   would have to  be  either to the groundwater or to nearby White
River,   downstream  of the water supply intake  line.   The groundwater is
being  used  for  some  small   irrigation  wells  near the sites  and some
individual   domestic  wells   1   to  2 miles {1.6  to 3.2 km) away.   It is
anticipated  that  Angus  may   some  day  use groundwater as well  as the
surface  supply  to meet  future water demands.  Therefore, discharges to
the groundwater would have to meet existing requirements.
For  discharge  to  White   River,   the  Department  of Ecology,  State of
Washington,  has stipulated  the  following effluent quality limitations:
                            BOD - 10 mg/L
                            SS  - 10 mg/L
                            Total N - 15 mg/L
                            Total P - 5 mg/L
                            Fecal col i forms -
200/100 nt
                            Maximum residual chlorine - 0.5 mg/L
                                    6-24

-------
Using  Table 6-6,  a  slow  rate  or  rapid  infiltration system is applicable
to Site A.  Sites  B  and C could have  either a slow rate or overland flow
system,  while a   slow rate  system appears  to be the only  choice  for
Site D.  As  all   systems are  capable of meeting  or exceeding  the dis-
charge requirements,  system  selection  (except  for  rapid infiltration)
will be based on the  soil  permeability  ranges.


For  rapid infiltration rates  on  Site A,  limited field tests are needed.
Using the guidelines  in Appendix  F one  test pit was dug down to 10 ft (3
m)  to verify lack of restrictive layers  in the soil  profile.  Using the
procedures  from   Appendix  C   (Section  C.3.1.4.3)  three  double  ring
infiltrometer  tests  were conducted.  The resulting infiltration minimum
rate was determined  to be 5.0  in./hr  (12.7 cm/h).   Using Figure 3-3, the
wastewater  application   rate  is  determined to be 42.0 in./wk (1.1 m/wk)
which  is  5%  of  the clear water rate (the range in Figure 3-3 is 3 to
10%).   However, an  upper limit of 40.0 in./wk (1.0 m/wk) is recommended
for small rapid infiltration system design.  Based on 52 wk/yr operation
the annual rate is 173 ft/yr (52.7 m/yr).


To  compute  the   area required to treat the wastewater, Equation 6-1 is
used.  In keeping  with the conservative approach to small system design,
the  lower  permeability   values  are  used  to  obtain  the  equivalent
application rate,  R,  from Table 6-8.  Also, the average annual  rainfall,
including  a reduction for evapotranspiration (assuming a colder month),
is  added to the rate of  application  R.   As an example, a calculation to
derive the area required  for a slow rate  system at Site A is shown:

     L =  46 weeks (52 for rapid  infiltration - Figure 6-2)
     R =  SCS permeability range  plus (precipitation-evapotranspiration)
       =  (1.5 + 0.5) in./wk = 2.0 in./wk (5.0 cm/wk)
     Q =  0.26 Mgal/d x 365  =  94.9 Mgal/yr


                   F  = 36*  x    '9 -  38 acres (15.4 ha)
The acreages calculated for each  site and  treatment  process are shown in
Table 6-14.

                               TABLE 6-14

           REQUIRED ACREAGES FOR  ANGUS LAND TREATMENT  SYSTEMS

                               Soil       Application    Treatment site
           Site               permeability, in./h rate, in./wk  requirement, acres
A

B

C

Slow rate
Rapid infiltration
Slow rate
Overland flow
Slow rate
Overland flow
0.6
5.0
0.6
0.2
0.2
0.06
2.0
40.0
2.0
8.0
1.5
4.0
38
1.7
38
10
51
19
           D   Slow rate            0.2          1.5         51


           1 in. = 2.54 cm
           1 acre = 0.405 ha
                                   6-25

-------
In comparing the required acreages with  Table  6-13,  Site  D  is  eliminated
on the basis of insufficient area.
     6.4.6  Preapplication Treatment,  Storage,  and Application  Methods


Preapplication  treatment practices for  various systems  are  indicated in
Table  6-9.   Unless surface application is  selected  for one of the  slow
rate  systems,  biological  treatment  with a minimum  of  7 days  detention
time is normally practiced.  This would  most likely be an aerated  lagoon
designed to reduce BOD,, to 60 mg/L or  less.


From  Figure 6-2, a storage of 40 days of flow  is advised.   The required
storage volume is as follows:

       260 000 gal/d x 40 days =  10.4  Mgal = 32 acre-ft  (39  500 m3)

    Storage pond size, assuming 10 ft  working depth (3 ft freeboard)
          = 3.2 acres + 25% for levees,  road =  4 acres (1.J5  ha)
This will be required for either the slow rate  or overland flow  systems.
The  rapid  infiltration  system should not require any storage  capacity
because  of  the  moderate  climate and permeable soils.   The methods  of
application  for surface irrigation systems are summarized in Table  6-11
for  various  land  conditions.   By comparing the application rates  from
the  third  column  of Table 6-14 and the average to maximum slopes  from
Table  6-13  to  the  values  given in Table 6-11,  the following surface
application methods are chosen:

     Site A - Graded border with any crop (minimum slope)
            - Graded contour levee with sod crops (for maximum slopes)
     Site B - Level border checks with any crop
     Site C - Graded contour levee with sod crops


As  the  land  preparation  costs  for  Sites   A  and  C would raise the
development  cost  beyond that required for Site B, the use of sprinkler
application should be investigated.  Using the  procedure outlined above,
the  remaining ' sites  are screened using the values given in Table  6-12
for sprinkler systems.  The preferred methods from this process  are:

     Site A -  Hand or tractor moved solid set
     Site C -  Hand moved solid set, self propelled, and permanent set
The land at Site A, already in agricultural  use,   contains some uniform,
rectangular fields.  Site C would require grading and preparation (i.e.,
more  cost)  to  enable  the  use  of  the more flexible,  less expensive
sprinkler systems.
                                  6-26

-------
 The   rapid  infiltration  system for Site A  and  the  overland flow system
 for   Site C are still feasible alternatives  according to the criteria in
 Sections  6.3.2  and  6.3.3.   The  need to  construct the 2 to 4% sloped
 terraces  at  Site  B  for  effective overland flow  would favor the less
 expensive grading required to prepare Site C.


 A  number  of  other  considerations  should be  included  in the cost-
 effectiveness analysis  for  small  systems  that  are discussed in other
 sections of this manual.  Recovery of renovated  water from beneath rapid
 infiltration basins or slow rate sites to either provide relief drainage
 from   perched  groundwater  or to recover water  for  sale is discussed in
 Section   5.5.   For  vegetation  selection,  and  revenue  generation by
 management  of a cash crop, Section 5.6 should be  reviewed.   The systems
 that   remain  to  be  analyzed  for cost effectiveness are summarized in
 Table 6-15.
                                TABLE 6-15

             LAND TREATMENT ALTERNATIVES FOR ANGUS, WASHINGTON
                     Land treatment
              Site       system             Major feature


               A    Slow rate         Tractor moved solid set sprinklers

                    Rapid infiltration  Prepare the 15 acre-site

               B    Slow rate         Level border strips

               C    Slow rate         Hand moved solid set sprinklers

                    Overland flow      Grade terraces and ditches
     6.4.7  Other Considerations
On the basis  of  nonmonetary criteria, Site B holds a clear advantage--!'t
is  already   owned  by  the city and would provide needed irrigation water
for the future greenbelt.


If rapid infiltration  is  shown to be more cost effective than irrigation
at  Site  A,  the purchase or lease of the site would be necessary.  For
the  irrigation  system  at Site A, purchase would not be necessary  if  a
long-range  contract could be negotiated with the owner.  Since the  land
at  Site  A   is  presently being irrigated, the renovated water could be
offered  at   an  equal  cost and the farmer would have the added advantage
of the wastewater nutrients.
                                   6-27

-------
Site  C  would  require  the purchase or lease of a suitable area  if  the
overland  flow  alternative  were  shown  to  be  more  cost  effective.
Sprinkler  irrigation  would  convert  nonirrigated  pasture  into more
valuable  land  and should make a long-term lease more attractive  to  the
owner than was the case, at Site A.


If  some  alternatives  appear  to   be very close to each other for cost
effectiveness,  the  consideration  of these nonmonetary items may  be  the
basis for the final site selection.


     6.4.8  Summary of Design Example


The  total  land  requirement  will  be the sum of the acreage needed  for
pretreatment  facilities, the actual  area to be wetted, buffer zones  (if
required),  access  and  service  roads,  and  storage ponds.  The major
elements  of  each  alternative  and  the  total  land  requirement  are
summarized in Table 6-16.
6.5  References
1.   Sullivan,   R.H.,   et   al.      Survey   of   Facilities   Using  Land
     Application of Wastewater.   Environmental Protection Agency, Office
     of Water Program Operations.   EPA-430/9-73-006.  July 1973.

2.   Loehr, R.C.  Agricultural Waste Management—Problems, Processes  and
     Approaches.  New York,  Academic Press.   1974.

3.   Metcalf  &  Eddy,   Inc.  Wastewater Engineering.   New York, McGraw-
     Hill  Book Co.  1972.

4.   Francingues,  N.R.,   Jr.  and   A.J.   Green,  Jr.    Water Usage  and
     Wastewater  Characterization   at  a  Corps   of  Engineers Recreation
     Area.   U.S. Army Engineer Waterways Experiment  Station,  Environmen-
     tal  Effects Laboratory. Miscellaneous  Paper Y-76-1.  January  1976.

5.   Minimum  Design  Standards   for  Community   Sewerage Systems.  U.S.
     Department  of  Housing  and Urban Development.  FHA G 4518.1.   May
     1968.

6.   Whiting,  D.M.  Use of  Climatic Data in Estimating Storage  Days  for
     Soil  Treatment Systems.  Environmental  Protection  Agency, Office of
     Research and Development.   EPA-IAG-D5-F694.  1976.

7.   Turner,   J.H.   Planning   for  an  Irrigation   System.   American
     Association  for  Vocational   Instructional  Materials.   Athens,  Ga.
     1971.

8.   Parmelee, D.M.  Personal  Communication.  May 1977.
                                 6-28

-------
cn
i
rvs
10
                                                                          TABLE  6-16
                                      SUMMARY OF FEASIBLE  LAND TREATMENT SYSTEMS FOR ANGUS, WASHINGTON
Preapplication
treatment

Site
A



B


C


Land treatment
system
Slow rate,
sprinkler
Rapid infil-
tration
Slow rate,
surface
Overland flow
Slow rate,
sprinkler
Overland flow

Level3
S

P

Se

P

S
P
Area,
acres
3

2

3

2

3
2
Wetted
Application
area
Area,
rate, in./wk acres
2.0

40.0

2.0

8.0

1.5
4.0
38

1.7

38

10

51
19
Buffer

Needed
Yes

No

No

No

Yes
No
zones'3
Area,
acres
8

0.2

4

1

10
2
Storage
Days
of flow
40

Od

40

40

40
40
Area,
acres
4

.

4

4

4
•4
Total area
Disinfection Discharge0 required, acres
Yes Groundwater

No Groundwater

Yes Groundwater

Nof White River

Yes Groundwater
Nof white River
53

4

49

17

68
27
                  a.  S = Secondary;   P  =  primary.
                  b.  May be required in some states.  Average  requirement based  on 20% of wetted  area and includes  10% for service roads.
                  c.  If the discharge is  to a groundwater,  the nitrogen balance  of the system should be checked using methods outlined  in
                     Chapter 5.  Nitrate  (NOj) measured as  nitrogen, should not  exceed 10 mg/L in this case.
                  d.  Includes extra  freeboard for storage within basins.
                  e.  Because of public contact.  Under controlled conditions, primary treatment without disinfection would be sufficient.
                  f.  Unless discharge coliform standard cannot be met—then post-treatment disinfection is necessary
                  1  acre = 0.405 ha
                  1  in./wk = 2.54 cm/wk

-------
                                         CHAPTER  7
                                       CASE STUDIES
7.1    Introduction
Eleven  case   studies   are  presented   in this  chapter to illustrate the
variety of existing  land treatment systems.   Six of the  case  studies are
slow   rate  systems;    three   are  rapid  infiltration systems;  and two are
overland   flow   systems.    Locations  of  the  case studies  and  some system
characteristics  are  presented for comparative purposes in Table  7-1.
                                          TABLE 7-1
                                 SUMMARY  OF  CASE STUDIES
      Location
  Avg   Avg annual
 flow,  application
Mgal/d  rate,  ft/yr
                                              Degree of
                                             preapplication
                                              treatment
 Application technique
No. of years
in operation
 S1 ow ro to
   Pleasanton, California     1.4      8.5

   Walla Walla, Washington
    Industrial             2.1      1.7
    Municipal              6.8

   Bakersfield, California    14.7      6.9
   (existing system)
   San Angelo, Texas         5.8     10.3
   Huske'gon, Michigan        28.5      6.0
   St. Charles, Maryland      0.6     10
 Rapid infiltration
   Phoenix, Arizona          13      364
   Lake George, New York      0.7    140
   Fort Devens,
   Massachusetts            1.3     94
 Overland flow
   Pauls Valley, Oklahoma     0.2    19-45
   Paris, Texas              4.2      5.2
   (industrial)
                  Secondary (plus
                  aerated holding ponds)
                 Aeration
                 Secondary

                 Primary

                 Primary
                 Aerated lagoons
                 Aerated lagoons

                 Secondary
                 Secondary

                 Primary
                 Raw (screened)
                 and oxidation lagoon

                 Raw (degreased and
                 screened)
Sprinkler (portable pipe)      20
Sprinkler (buried pipe)         5
Sprinkler and surface         78
(ridge and furrow)
Surface (border strip and      38
ridge and furrow)
Surface (border strip)         18
Sprinkler (center pivot)        3
Sprinkler (surface pipe)       12

Surface (basin flooding)        3
Surface (basin flooding)       38

Surface (basin flooding)       35
Surface (bubbling orifice)       2
and sprinkler (fixed and
rotating nozzles)
Sprinkler (buried pipe)        13
 1  Mgal/d = 43.8 L/s
 1  ft/yr = 0.305 m/yr
                                           7-1

-------
In  addition  to  the  mix of design flows  and  climates  represented,  the
ages of the systems vary from several  decades  (Walla,  Walla,  Washington;
Bakersfield,  California;  and  Lake George, New  York) to  relatively  new
(Muskegon, Michigan; Pauls Valley,  Oklahoma; and  Phoenix,  Arizona).   The
last  two  systems  are  principally demonstration  projects with  process
optimization  the  major objective.  Nearly all the cases  have  attracted
some research interests and the ongoing  research  is discussed separately
from the normal  operation.
Capital  and  operating  costs  are  included   when   reliable   data   are
available.  Costs for research projects  are  not comparable  to  design  and
construction costs for normal  municipal  systems.


7.2  Pleasanton, California


     7.2.1  History
Pleasanton,  California,  with  a  population  of  approximately  35  000  is
located  40 miles east of San Francisco.   Wastewater irrigation has  been
practiced  here  since  1911,  when  the  population was  2  000 and  only 8
acres  (3.2  ha)  of  land  was  utilized  [1].    The agricultural  land
apparently  has  been in continuous use,  although historical  records are
absent.   The  present  system  has  been  in   operation since  1957, and
consists of the sprinkler irrigation of 1.4 Mgal/d (61 L/s)  of  secondary
effluent  on pastureland for the grazing  of beef  cattle  (see Table  7-2)
[2].  Only  17 000  of  the  total   population  is  served  by   the  land
treatment  system.   The  remaining  population  is served by a separate
treatment  plant.   The  city is experiencing  rapid growth;  as  a result,
plans  are  underway to provide a regionalized sewer system, which calls
for abandonment of the irrigation system  in 5  years.  It should be noted
that abandonment in 5 years was also predicted in 1972 [3].
     7.2.2  Project Description and Purpose


There  are  two  primary  objectives  to  be  met in this land treatment
system:   (1) to  provide  proper  management  of wastewater,  and (2)  to
produce  a  high  quality  forage  crop  for  beef cattle grazing on the
wastewater-irrigated fields.  This system has proved to be successful  in
meeting both of these objectives.
The pastureland receiving wastewater is essentially level  and sprinklers
apply  water consecutively to all  parts.  Soils range from gravelly loam
to  clay  loam  and  are  moderately  to  slowly  permeable.   There is a
nonirrigated  hill of 19 acres (7.7 ha) adjacent to the field area where
cattle  can  be  quartered  when the fields become somewhat soggy during
inclement  weather. This  is  done  to  protect  the soil  from excessive
                                  7-2

-------
compaction  by   the  cattle during wet weather and  to prevent the cattle
from contracting hoof  diseases  as a result of  the wetness.
                                     TABLE  7-2
                                  DESIGN FACTORS,
                             PLEASANTON, CALIFORNIA
      Type of system
      Avg flow,  Mgal/d
      Type of wastewater

      Preapplication treatment
      Disinfection
      Storage
      Field area, acres
      Crops
      Application technique
      Routine monitoring
      Buffer zones
      Application cycle
        Time on, h
        Time off, wk
      Annual application rate, ft
      Weekly application rate, in.
      Avg annual precipitation, in.
      Avg annual evaporation, in.
      Annual nitrogen loading, Ib/acre
      Capital costs, $/acre
      Operation  and maintenance costs, 4/1000 gal
Slow rate
1.4
Primarily domestic; some winery,
cheese, and metal wastes
Secondary (plus  aerated holding ponds)
Not required
Not required
184
Forage grass
Sprinkler, portable
Yes
No

12-16
5
8.5
2.2
18
71
325
845
10.4
      1  Mgal/d = 43.8 L/s
      1  acre - 0.405 ha
      1  ft = 0.305 m
      1  in. = 2.54 cm
      1  Ib/acre = 1.12 kg/ha
      1  $/acre = S2.47/ha
      1  4/1000 gal = 0.264 c/m3
      7.2.3   Design  Factors
The   land   treatment  site   is   schematically   depicted   in   Figure 7-1.
Two  holding   ponds   receive  unchlorinated  effluent from the  undersized
secondary   treatment  plant.    The  two   ponds   are  aerated   to  prevent
septicity   prior  to  application   and  to  provide  further   biological
treatment.    The  two  ponds   total   4 acres (1.6 ha)  and provide 5 Mgal
(18  925 m3)  storage  capacity,  which  equalizes   the diurnal  flow to  the
sprinkler  irrigation system [1].
                                       7-3

-------
                            FIGURE 7-1

                       LAND TREATMENT SYSTEM,
                         CITY OF  PLEASANTON
     ©
     vvv .
     XXSH
    kvxxH
     VSNN
6ROUNDIATER SAMPLING
 STATIONS

IRRIGATED  FIELDS


NONIRRIGATED  FIELDS


STORAGE  FACILITIES
                                                                   SECONDARY
                                                                   TREATMENT
                                                                     PLANT
                                                                    4 acres
                                                                     AERATED
                                                                  HOLDING PONDS
                                                                  19  acres
                                                                  NONIRRIGATED
                                                                     HILL
                                                      EMERGENCY
                                                       STORAGE
                                                    VAPORATION AREA
1  acre = 0.405 ha
                                   7-4

-------
A  75  hp (56 kW) pump, with an identical  standby unit located at the  end
of  the holding ponds, delivers wastewater to the field area via  a 10  in.
(25 cm)  aluminum  main line.  A portion of the irrigated pastureland  and
the  main  line  is  shown  in  Figure  7-2.   The portable lateral  system
consists  of  30 ft  (9 m) sections of 3 in.  (7.5 cm)  aluminum pipe, each
containing a riser with an  impact-type sprinkler head as shown in Figure
7-3.   Each  nozzle delivers 10 to 11  gal/min (0.7 L/s) and has a wetting
radius of 30 ft (9 m) [2].
Tail water  and  stormwater  control   is  provided  by peripheral  drainage
ditches that discharge into 18 in. (45 cm)  and 10 in. (25 cm)  steel  lines
and  thence  to a runoff collection  pond.   This 10 acre (4 ha)  pond  has  a
26 Mgal  (98 400 m3) storage capacity and  is provided with an  overflow to
an  emergency  storage  evaporation   area.   The 40 acre (16 ha)  emergency
storage  area  is  designed  to handle the  increased flows from a 50 year
storm.   Normal  runoff water, occurring from about November to March, is
recycled within the system by a 100  hp (75  kW) pump.


     7.2.4  Operating Characteristics and  Performance


The  irrigation  system is operated  7 days  a week,  year-round.   A normal
pumping schedule of 12 to 16 hours per day  maintains the holding ponds at
a  fairly  constant  elevation.   Pumping   is  by  manual  control  with an
automatic shutoff if the ponds drop  to a certain level.


The irrigated pastureland supports a herd  of 600 beef cattle.   The cattle
are rotated to fenced plots ahead of irrigation.  The laterals  containing
the  sprinklers  are  moved  60 ft (18.3 m) each day, which results  in an
application  cycle  of  5 weeks.  The cattle are provided with  a separate
supply  of  drinking  water  at  one end of the pasture.  The  cattle have
experienced  no  ill effects from consumption of the grass; the marketing
and sale of the beef occurs in a normal manner.
The  pasture  grass  seed  consisted  of 44% tall  fescue,  32% Italian  rye
grass, 20% orchard grass, and 4% mixed grasses [2],   Sudan grass  is  grown
on  the  emergency  storage  field and is used as  supplemental  feed.   The
grasses  are  cut  twice  a  year  with a rotary mower in  order to induce
better growth and to control  weeds such as star thistle.   Fertilizers  and
pesticides have not been used.
Values  for various wastewater constituents found in  the irrigation  water
prior  to  application  are  presented  in Tables 7-3  and 7-4.   Although
influent   total    suspended   solids   to   the  irrigation  system  are
approximately   25   mg/L,   no   nozzle-plugging-   problems   have   been
experienced; the nozzle diameter is 0.44 in.  (1.1  cm).
                                  7-5

-------
                   FIGURE  7-2



  IRRIGATED PASTURELAND,  PLEASANTON,  CALIFORNIA

                   FIGURE 7-3




PORTABLE SPRINKLER SYSTEM, PLEASANTON, CALIFORNIA
                       7-6

-------
                                TABLE 7-3

               CHARACTERISTICS OF HOLDING POND  EFFLUENT AND
               GROUNDWATER QUALITY, PLEASANTON,  CALIFORNIA
Concentration, mg/La
Constituent
BOD
COD (low level)
Total suspended solids (TSS)
Total dissolved solids (TDS)
Total organic carbon (TOC)
Nitrogen
Organic
Ammonium (NH4-N)
Nitrate (N03-N)
Nitrite (N02-N)
Total phosphorus
PH
Temperature, °C
Boron (B)
Chloride (Cl)
Fluoride (F)
Sodium {Na+)
Calcium (Ca^)
Magnesium (Mg++)
Potassium (K+)
Bicarbonate (HCOa)
Carbonate (COs)
Hardness (Ca, Mg)
Non-carbonate hardness
Alkalinity as CaCOs
Specific conductance, pmhos/cm
Sulfate (S04)
Silica (Si02)
Iron (Fe)
Sodium adsorption ratio (SAR)
Sodium, %
Depth of groundwater below land .surface, ft
Holding pond
effluent^
22
25
702
39
3.0
24.6
<0.02
0.01
4.8
8.4
0.73
97
0.17
130
78
23
520
3.6


972


3.3

Groundwater quality0
G-7

30
980
4.3

0.13
0.02
0.02
6.8
17.4
0.0008
125
0.7
150
92
90
0.8
897
600
0
736
1 640
53
16
0.0006
2.7
35
7.5
G-9

5
708
8.2

4.9
0.01
0.02
6.9
16.8
0.0007
111
0.1
no
93
55
3.0
491
460
56
403
1 190
120
23
0.00001
2.2
34
37.3
a. Unless indicated otherwise.
b. Data for September 1975 [4].
      c.  Data for November 1975 to August 1976 [5].
         wells G-7 and G-9.

      1 ft = 0.305 m
See Figure 7-1 for location of
Industrial  inputs  to the system include small  flows  from a highly acidic
but  seasonal waste from a winery, a pretreated  cheese factory effluent,
a pretreated metal  waste, and a seasonal loading  from the Alameda County
Fair.   There   is   no odor in the areas irrigated with wastewater and no
odor from the holding ponds.  Odors have been  a  problem at the treatment
plant  in   the   past,  and as a result the trickling  filter and settling
tanks have  been  covered.
                                    7-7

-------
                               TABLE  7-4

        TRACE WASTEWATER CONSTITUENTS OF  HOLDING  POND  EFFLUENT,
               PLEASANTON,  CALIFORNIA,  SEPTEMBER  1975  [4]
Constituent
Arsenic (As)
Barium (Ba)
Cadmium (Cd)
Chromium (Cr+6)
Cyanide (Cn)
Lead (Pb)
Mercury (Hg)
Selenium (Se)
MBAS
ATdrin
Chlordane
DDT
Dieldrin
Endrin
Heptachlor epoxide
Lindane
Methoxychlor
Toxaphene
2,4-D
2,4,5-TP
Carbon chloroform extract (CCE)
Carbon alcohol extract (CAE)
Holding pond
effluent, mg/L
<0.006
<0.1
<0.005
<0.005
<0.05
0.05
0.0003
<0.005
2.6
<0. 00005
<0. 00005
<0. 00005
<0. 00005
<0. 00005
<0. 00005
<0. 00005
<0. 00005
<0. 00005
<0.1
0.001
2.52
17.24
     7.2.5  Costs


The  City of Pleasanton leases most of the  farmland from  the  City of  San
Francisco  which  owns  it  as  an  underground   water  reserve.  Grazing
permits  for  the  184 acre   (74  ha)   irrigated   pastureland are  then
allocated to local  farmers by auction.   This  land is sublet at an annual
rental   fee  of $100 to $110/acre  ($247 to  $272/ha)  with  a  2  year lease.
The  city  furnishes  the  irrigation   system and the  labor  to move  the
portable pipe.  The farmer manages the cattle and the pasture grass.
Labor requirements to move the
hours  per  day, 7 days a week,
pipes,  nozzles,  and  fencing
consists  of about 27 000 kW'h
22 000 kW-h  per month for the
kW;h  per  month.  A breakdown
for this land treatment system
irrigation system involve 3 men at  2-1/2
  Maintenance costs for repairs to pumps,
are about $5 000/year.  Power consumption
per month for the 100 hp (75 kW) pump and
75 hp (56 kW) pump, for a total of 49 000
of the approximate annual operating costs
is shown in Table 7-5.
                                   7-8

-------
                                     TABLE 7-5
                  APPROXIMATE  OPERATION AND MAINTENANCE  COSTS,
                             LAND TREATMENT SYSTEM,
                           PLEASANTON,  CALIFORNIA  [2]
                               Expenditure"         Annual  cost
Labor3
Taxesb
Power0
Material
Administration
Other
Subtotal
$22 000
21 000
19 000
5 000
500
5 000
$72 500
                       Revenue from grazing rightsd    -19 3QQ
                          Total              '       $53 200
                       Operation and maintenance
                       costs, 
-------
     7.2.6  Monitoring Programs


Since  the  land  treatment  operation  is  conducted  over an important
underground  aquifer,  careful   monitoring  of   groundwater  quality   is
mandatory.   The  California  Regional   Water Quality Control  Board,  San
Francisco   Bay   Region,   requires  regular  groundwater  sampling   at
Pleasanton,  and  to  meet  this  requirement  a  number  of groundwater
monitoring  wells  have  been  installed.    These  wells serve to ensure
compliance  with  state  regulations  and  are providing research data to
assess  overall  groundwater impacts in the adjacent area.  The location
of  these  wells was shown in  Figure 7-1.  Groundwater quality data  for
two  representative  wells  were  presented  in Table  7-3, covering  the
period from November 1975 through August 1976.


The  Pleasanton  land  treatment site is located within a mile of a city
development of more than 10 000 people. There  are essentially no buffer
zones;  however,  the site is 'totally enclosed  by fences to limit public
access.   A  health  effects  study  is being conducted by the Southwest
Research Institute.  Scientists are performing  measurements to determine
the  extent  of aerosol dispersal  and are  analyzing irrigation water  and
aerosols  for  the  presence of pathogenic microorganisms and chemicals.
The results  and conclusions of this study are  not available at the time
of this report.


7.3  Walla Walla, Washington


     7.3.1  History
The  use  of  wastewater  as a source for irrigation water began in 1899
when  the  City  of  Walla  Walla  installed  its  first sanitary sewage
collection   system  and  discharged  directly  to  Mill   Creek  without
treatment.   Irrigators  still  withdraw  water from the creek for their
truck  crops.   As the population increased and the system expanded, the
wastewater  became  a  larger  portion  of total  stream flow,  especially
during the summer months.


In 1929, the city constructed a 7.5 Mgal/d (328 L/s) secondary treatment
plant  to  treat domestic and industrial  flows.  In 1953, the  industrial
(food processing) wastes of about 3 Mgal/d (131 L/s) were separated from
the  plant and from 1953 to 1962, industrial wastewaters were  treated at
the  source  by  the  food  processors.   In 1962, industrial wastewaters
began  to  receive  treatment  in  an 8 Mgal/d (350 L/s) separate plant
operated  by  the  city.   The  industrial   wastewater  was screened, pH
adjusted to 7.0, and directly discharged to Mill  Creek.


In  1972,  the  domestic  plant was upgraded to provide a higher quality
effluent  and  now  has  an  average treatment capability of 9.12 Mgal/d
                                  7-10

-------
(400 L/s) and a maximum hydraulic capacity of 13 Mgal/d (569 L/s).   This
same year, a  sprinkler  system for application of industrial  wastewater
was completed for all industrial effluent  not  required for stream flow
augmentation.  Stream  flow., augmentation  is  required  to  maintain., a
minimum  flow  of  11.25 ft /s  (318 L/s) in Mill  Creek  and 1.77  ft /s
(50  L/s)  in  the  irrigation ditches.  This source of irrigation  water
becomes  essential  in the summer, when upstream users divert all  of the
normal  Mill  Creek flow.  Design factors for the industrial  wastewaters
(city operated) and municipal  wastewaters (privately operated) slow rate
systems are presented in Table 7-6.
                                TABLE 7-6

                            DESIGN FACTORS,
                        WALLA WALLA, WASHINGTON

Type of system
Avg flow, Mgal/d
Type of wastewater
Preapplication treatment
Disinfection
Storage
Field area, acres
Crops
Application technique
Routine monitoring
Buffer zones
Application cycle, wk
Time on
Time off
Annual application rate, ft
Weekly application rate, in.
Avg annual precipitation, in.
Avg annual evaporation, in.
Capital cost, $/acre
Operation and maintenance
costs, 4/1 000 gal
a. City operated system.
b. Irrigation districts, privately
1 Mgal/d = 43.8 L/s
1 acre = 0.405 ha
1 ft = 0.305 m
1 in. -- 2.54 cm
1 Ib/acre =1.12 kg/ha
1 $/acre = $2.47/ha
1 4/1 000 gal = 0.264 t/m3
Industrial
Slow rate
2.1
Food processing
Aeration
No
Not required
700
Alfalfa
Sprinkler (buried pipe)
No
No

1-2
6-8
1.7
0.7
15.5
41
2 500

4.0

operated.







Municipal
Slow rate
6.8 (municipal effluent to creek in winter)
Domestic
Secondary
Yes
Not required
940
Vegetables
Sprinkler and surface (ridge and furrow)
Yes
No

Varies with crop
Varies with crop
Varies with crop
Varies with crop
15.5
41
--

4.3









                                 7-11

-------
     7.3.2  Project Description and Purpose


The  treatment  plants  for  all   of  the  city's  industrial  and domestic
wastewaters  are  located  on  an approximately 40 acre (16.3 ha)  site  2
miles   (3 km)   east   of  the   city.    Additionally,  the  city  owns
approximately 1 000 acres (405 ha) of land 0.6 mile (1  km)  north of this
area  for  the  sprinkler  irrigation  of  effluent  from the industrial
treatment  plant.   Of  the  1 000 acres,  about   700 acres (285 ha)  are
presently being used with the remainder being held in reserve for future
expansion.


          7.3.2.1  Municipal  System


Incoming  domestic  wastewaters  are received in  an aerated grit chamber,
sent  to  the  primary  clarifiers, then to  the three high-rate trickling
filters.   Next is intermediate clarification followed by a standard rate
trickling  filter  and  two  final  clarifiers.    Sufficient  chlorine  is
injected  upstream  of the final  clarifiers  to maintain a 0.1  to 0.5 mg/L
residual in the final  clarifier effluent.  The final  clarifiers double  as
chlorine contact tanks. The effluent is then discharged to a holding pond
from  which  it  flows  to either the irrigation  districts or Mill  Creek.
The city normally does not apply domestic  effluent to its own land.


          7.3.2.2  Industrial System


During  the  canning  season (April through  November) wastewater from the
area's food processors (mostly locally grown vegetables)  is pretreated  at
the  packers.   All  solids  above  a  #20 mesh   (0.833 mm  diameter) are
screened  from the waste stream before discharge  to a separate collection
system.  The influent is then received at  the plant in an aeration basin,
aerated, and pumped to the city's sprinkler  irrigation field.


          7.3.2.3.  Municipal/Industrial  Interconnections


To  maintain  treatment  flexibility,  there are  three operable intercon-
nections between  the  two  normally  separated   treatment   systems.  A
schematic flow diagram for the municipal and industrial treatment systems
is  shown  in Figure 7-4.  During low industrial  waste flow periods, when
there  is  insufficient  flow  to operate  the city (industrial) sprinkler
system  or when makeup water is needed to  meet the irrigation commitment,
a line from the industrial aeration basin  connects directly to the end  of
the  municipal  primary  clarifier.   This  has caused some problems with
excessive  vegetable  oils at certain times  of the year so this line will
be  rerouted  to  ahead  of  the  aerated  grit chamber, allowing complete
primary  treatment  of  these oils.  Another line allows diversion of the
raw  industrial wastewater directly to the standard rate trickling filter
                                  7-12

-------
                          FIGURE 7-4

    SCHEMATIC FLOW  DIAGRAM, WASTEWATER  TREATMENT
             PLANT, WALLA WALLA,  WASHINGTON
            INDUSTRIAL
            INFLUENT
           2. 6 Mgal/t)
                             FUTURE;
            INDUSTRIAL AERATION    r
            BASIN AND PUMPING STATION!
                 DOMESTIC
                 INFLUENT


                 6.8 Hgal/d
                                          GRIT
                                          CHAMBER
                                          MIXING
                                          CHAMBER
ALTERNATE DISPOSAL
IN MILL CREEK
(WINTER) 6.8 Mgal/d
                                             PRIMARY
                                             CLARIFICATION
                  STANDARD RATE
                  TRICKLING FILTER
I. 2 iga l/d
TO  GOSE
IRRIGATION
DISTRICT
                                                     INTERMEDIATE
                                                     PUMPING STATION
                                               FINAL
                                               CLARIFICATION
                                               TANKS
6.3 Mgal/d TO BLALOCK  IRRIGATION DISTRICT
                                                           •*•
                                                I Mgal/d= 43.8 L/s
                                7-13

-------
if  the  industrial  flow is extremely low relative to municipal influent.
A  third   line,   which is normally not used,  allows municipal effluent  in
the  final   effluent  holding  pond  to  be   pumped to the city sprinkler
system.    A   fourth   line,  diverting  raw  industrial  wastewater to the
aerated grit chamber, is in place but inoperable  due to leakage problems.
     7.3.3   Design Factors
Operation   of   the  city  sprinkler
November   each   year  for  the  food
irrigation  water  by  the districts
that  a  part of the industrial flow
being  used for  makeup to meet the
patterns for the sprinkler operation
      system  normally  occurs  from May to
       processing  wastewater.   Demand for
      occurs from May through September so
      goes  to the city tract with  the  rest
      irrigation demand.  The monthly  flow
      are presented in Table 7-7.
                                 TABLE 7-7

                     AVERAGE DAILY FLOW OF WASTEWATER,
                          WALLA WALLA, WASHINGTON
                                   Mgal/d
                                 May  Jun   Jul   Aug  Sep   Oct  Avg
          Municipal wastewater3

          Industrial wastewater

           Total

          Irrigation district demand
7.1   7.3

1.2   3.7
7.0

4.0
7.0

3.1
8.3  11.0 11.0  10.1

7.5   7.5  7.5   7.5
6.4   6.0

2.0   2.9

8.4   8.9

7.5   7.5
6.8

2.8

9.6

7.5
          Net flow to city owned
          sprinkler irrigation fields   0.8  3.5   3.5   2.6
                  0.9  1.4   2.1
          a.  From wastewater treatment plant operations monthly report

          1 Mgal/d = 43.8 L/s
The  city's   700  acre (285 ha) irrigation  site  is divided into 8 separate
subareas,  the  largest being 145 acres  (69  ha);  the smallest 60 acres  (24
ha); with an  average size of about 87 acres (36  ha).


There is no formal  plan for operating the  city  sprinkler system.  Each of
the  subareas   is irrigated for a period of 1 to 2 weeks.  The lack of an
operational   schedule   and  flow  records  for  each  plot  means  that
application   rates  can  only  be   estimated.    The  calculated  average
application   rate  based  on  6 months  flow to  the field was presented in
Table 7-6.    Soils  are  principally  well  drained silt loams with slopes
ranging from  2  to over 20%.
                                   7-14

-------
     7.3.4    Operating   Characteristics   and    Performance   of  City's
              Irrigation System


The industrial effluent for city operated sprinkler application is  pumped
against  a  maximum  static  head  of 50 ft (15.2 m).   At the  farm,  it is
distributed to 8 separate fields through 187 laterals  and 6  500 sprinkler
heads.   A  gage  pressure as high as 140  lb/in.2  (96  N/cm2)  is  main-
tained in the main distribution line with pressure at the heads in  the 95
to  100 lb/in.2 (67-70 N/cm2)  range.   Even with some slopes  on the site
exceeding  20%,  there  is  evidence  of  only  minor  erosion.  The city
sprinkle'r  system  employs  two types of heads,  the impact nozzle and the
large  diameter  gun.  The latter type, shown in  Figure 7-5,  distributes
325 gal/min  (1 260 L/min) at  100 lb/in.2 (70 N/cm2)  with 410 ft (125 m)
diameter of coverage.
At the high operating pressures, there is a problem of breakage  of  joints
between  the  risers  and the lines and between the risers and the  impact
heads.   There  is  also a problem of breakage of the heads and  risers  by
the  mower  because of lack of visibility of the heads when the  crops are
highest  prior to mowing.  The type of mower used and an impact  sprinkler
are shown in Figure 7-6.


The  principal  crop  being grown on the city's irrigated plot is alfalfa
for  hay.  The fanning operation is contracted with a local  farmer  who  is
paid  on  an  acreage,  bale, or weight basis according to the task being
performed.   For  example, mowing and windrowing is paid for by  the acre.
The  city  stores  the  bales  and  sells  them  when markets are strong.
Protein quality of the hay is good, averaging 14.5% by weight with  a high
of 21.0% and a low of 9.4%.
Although  the  BOD  of  the  industrial  effluent could be considered  high
(average = 965 mg/L),° there were no indications of nuisance conditions  at
the  application site nor have complaints been noted from the  surrounding
residents.
     7.3.5  Irrigation of Municipal  Effluent by Private Districts


Application  rates  of  the  municipal   effluent  used  by the irrigation
districts  are difficult to estimate as no records are kept.   The  Blalock
irrigation  district  consists  of  840  acres  (339   ha)   and  the   Gose
irrigation district is approximately 100 acres (40 ha) in  size.  District
farmers  withdraw  water  directly  from  the  ditches  or Mill  Creek for
sprinkler  or  flood  irrigation,  depending upon the time of year or the
crop.   On  the  average,  sprinklers are of the 6 to 7 gal/min  (23  to 26
L/min)  type  covering an area 40 ft by 60 ft (12 m by 18  m).  Sprinklers
are  allowed  to  run  3 to  6 hours  before being rotated to a  different
parcel.  This gives application rates ranging from a  potential  minimum of
0.7 in./d (1.8 cm/d) to a maximum of 1.7 in./d (4.3 cm/d).
                                  7-15

-------
                         FIGURE 7-5

         LARGE DIAMETER SPRINKLER GUN FOR INDUSTRIAL
   WASTEWATER APPLICATION USED AT WALLA WALLA,  WASHINGTON
                         FIGURE 7-6

     ALFALFA HARVESTING EQUIPMENT,  SPRINKLER RISER,  AND
IMPACT HEAD AT CITY IRRIGATION SITE,  WALLA WALLA,  WASHINGTON
                             7-16

-------
No distinction is made between water that is primarily or partly effluent
and  welV  or reservoir waters-in terms of crop selection.  Local  fanners
grow  whatever  has  an  attractive  market  price  without regard to  the
water's  source.   Effluent  irrigated  crops sell for as high a price as
noneffluent   grown   crops   and  there  has  been  no  case  of  market
discrimination.   This  was  confirmed  by a representative of one of  the
area's  food  processing  plants  who  purchases  large  amounts  of both
effluent and noneffluent irrigated vegetables.


Supplemental   nitrogen  (350  Ib/acre  [390  kg/ha]  of  48%  urea)   and
phosphorus  are  added  to the wastewater to increase crop yields. Crops
grown  on  domestic  effluent  irrigated land are (in decreasing order of
acreage):   onions,  carrots,  spinach, alfalfa (both for grazing and  for
harvesting),  radishes,  and  tomatoes.  Local farmers have not noted  any
decrease  in  yields  nor  deterioration  of  croplands over the years of
effluent  use.  Nuisance conditions caused by slime buildup have occurred
in  the past, but separation of the industrial wastewater in 1972 appears
to have solved the problem.


     7.3.6  Costs
Cost  data  are difficult to compare between the municipal  and industrial
systems.   For  example, treatment costs for the municipal  wastewater  are
borne by the irrigation districts and neither these costs nor the revenue
from the farming are included in the treatment plant accounts.  Likewise,
much of the time required to maintain the city farm and to administer  its
agreement  with  the  contracting farmer is not accounted for separately.
Neither  are  records kept on the portion of industrial effluent used  for
makeup  water  in  meeting  the district's contracted irrigation demands.
Last,  credit for crops sold does not accrue to the cost of operating  the
farm  but  is  returned  to  the revenue bond payers (the area's two food
processing  plants) to help  them  retire the debt for the sprinkler sys-
tem  construction.    The   estimated  operation  costs  are summarized in
Table 7-8.


The  capital  cost  for construction of the pumping station, transmission
lines,  distribution system, and control system for the 700 acre (286  ha)
sprinkler  irrigation  field  was  $1.7 million in 1971.  This amounts to
about $2 500 per acre ($6 000 per ha) construction cost.


     7.3,7  Monitoring Programs


The  only  continuing  monitoring  program  is carried out by the City of
Walla  Walla  for  the treatment plant operating records [6].  A specific
soils monitoring program was conducted in 1974 and repeated in 1976.   The
soils  in  the  city's  sprinkler  irrigation  operation  were sampled to
determine the effects of irrigation.  The adjacent 500 acre (204 ha) city
                                   7-17

-------
 tract   is a  nonirrigated  dry  land  farming area on which wheat  and  barley
 are  grown.   Soils  tests  taken  in  1974 of the nonirrigated  and irrigated
 parcels provide little  indication  of any differences  in conditions  after
 2 years of wastewater irrigation.


                                 TABLE 7-8

                     AVERAGE ESTIMATED OPERATIONS COSTS,
                          WALLA WALLA, WASHINGTON
                                    000 gal
                          Municipal system3 Industrial system*5
1973 3.4
1975 3.7
1976C 4.3
a. Treatment costs only.
b. Operates May-November,
distribution costs.
7.6
4.0
treatment and
                     c.  To July 1976.

                     1 
-------
surface  distribution  methods.
because of  the warm  arid climate.
   Year-round    irrigation  is   possible
Although   the  fanning  operation   has been successful  in  containing all
wastewater  within   the boundaries  of the  site and producing crop  yields
consistent with local  averages, certain deficiencies have  developed, and
upgrading  and expansion of  existing facilities are needed.   A summary of
principal   design   factors   for  both  the  existing  and   proposed land
treatment  systems  is presented in Table 7-9.
                                    TABLE 7-9
                                 DESIGN FACTORS,
                             BAKERSFIELD, CALIFORNIA
                                     Existing system
                       Proposed system
Type of system
Avg flow, Mgal/d
Type of wastewater
Preapplication treatment
Disinfection
Storage
Time, d
Capacity, Mgal
Slow rate
14.7
Primarily domestic, some
poultry processing waste
Primary
Not required
4
60
Slow rate
19.0
Primarily domestic
poultry processing
Aerated lagoons
Not required
90
1 710


, some
waste



 Field area, acres
 Crops
 Application technique

 Routine monitoring
 Buffer zones
 Application cycle, d
  Time on
  Time off
 Annual application rate, ft
 Maximum weekly application rate,  in.
 Avg annual precipitation, in.
 Avg annual evaporation, in.
 Annual nitrogen loading, Ib/acre
 Capital cost of proposed system,
 $/acrea
2 400
Forage, fiber, and seed
                       4 800
                       Forage, fiber, and seed
Surface (border strip and  Surface  (border strip and
                       ridge and furrow
                       Yes
ridge and  furrow)
No
No

1-2
7-15
6.9
4
6.4
60
466
                       No

                       0.5-1
                       10-15
                       4.5
                       4
                       6.4
                       60
                       280

                       2 960
 a.  Not including preapplication treatment or storage.
 1 Mgal/d = 43.8 L/s
 1 acre = 0.405 ha
 1 ft = 0.305
 1 in.  = 2.54 cm
 1 Ib/acre =1.12 kg/ha
 1 $/acre = $2.47/ha
                                      7-19

-------
     7.4.2    Existing   System  Characteristics,   Design   Factors,   and
              Performance
The existing land treatment system,  depicted  in  Figure  7-7,  consists of
a network of ditches and equalizing  reservoirs supplying the  fields with
wastewater  for border strip and ridge  and  furrow methods of  irrigation.
Although  the  topography  is  very   flat,  the drainage  is  from  north to
south  with  sump  pumps  along  the southern end to  return tail water to
stora.ge  ponds  (see  Figure 7-7).    Soils  range from fine  sandy loam to
clay  loam.   The  soils  are generally alkaline and  poorly drained with
dense  clay lenses at depths ranging from 10  to 15  ft (3 to 4.5  m) below
the surface.  This clay barrier produces perched water in areas  where it
is continuous and reduced percolation in areas where  it  is  not.
Two permanent groundwater aquifers  exist  at  approximate  depths of 100 to
200 ft  (30 to 60 m)  and at 300 ft  (90  m).   They are  separated by a clay
barrier,  and  the confined lower aquifer is used  for water  supply.  The
deep  wells  on  the   farm,  as  shown  in Figure  7-7, produce water for
supplemental   irrigation water.  The  quality in this  region, however, is
inadequate  for  potable  uses  as  a result of naturally occurring high
total  dissolved solids and nitrates.
The wastewater is primarily domestic  in  nature, with  only a  few  poultry-
processing plants  discharging  high-BOD wastes   to   plant   No. 1.   The
characteristics  of effluents from plant No.  1  (3.8 Mgal/d [166 L/s]) and
plant  No.  2  (10.9  Mgal/d  [477 L/s]) have  been   combined and  a  typ-
ical  blend  of  constituents  found   in the  irrigation  water is given  in
Table 7-10.
The  quality  of  the  combined  primary   effluent   is  quite  suitable  for
irrigation.   The  sodium  adsorption   ratio   is  relatively  high  at 7.5;
however, it is not critical.   The total dissolved solids  concentration  is
not a problem for any of the  crops grown.


Liquid  and  nitrogen  loading  rates,  and nitrogen requirements  for  the
principal   crops  grown  on the farm are  shown  in   Table  7-11.  As can  be
seen,  the  nitrogen applied  meets the  nitrogen uptake  of all crops.   For
cotton,  the  nitrogen  loading  is more  than twice  that  which can  be
utilized.    Applying excess nitrogen to cotton  promotes excess  vegetative
growth  at the expense of fruitive growth, resulting in decreased  yields.
Yields  for all  other crops are approximately  equal  to, and in  some cases
higher  than,  the  countywide  averages.   Crop  yields   resulting  from
irrigation  with  primary  effluent and  the economic return  per acre  are
presented in Table 7-12.
                                  7-20

-------
                 FIGURE 7-7
  EXISTING WASTEWATER IRRIGATION  SYSTEM,
         BAKERSFIELD, CALIFORNIA
             PLANT NO.  1
                RESERVOIR
PLANT NO.  2
 •LTH
  n
• RESERVOIR

N



DISTRIBUTION
DITCH-
        D
                 D
             STORAGE PONDS
                  PASTURE
                                       O
                                   0    1000  2000  3BOO


                                   SCALE        FEET
                                  LEGEND
                                 •    WELL

                                 A   TA I HATER
                                      RETURN
                                      STATION
                     7-21

-------
                               TABLE  7-10
              COMPOSITE  WASTEWATER  CHARACTERISTICS FOR
                      CITY PLANTS NOS.  1 AND 2,
                       BAKERSFIELD,  CALIFORNIA9
                 BOD, rag/Lb                  150
                 Suspended solids, mg/L         48
                 pH, units                     7.0
                 EC, mmhos/cm                  0.88
                 TDS, mg/L                   477
                 SAR                          4.1
                 SAR(adj)                      7.5
                 Calcium, meq/L                 2.30
                 Magnesium, meq/L               0.41
                 Sodium, meq/L                  4.74
                 Potassium, mg/L               26
                 Carbonate, meq/L               0
                 Bicarbonate, meq/L             3.57
                 Chloride, meq/L                3.01
                 Sulfate, meq/L                 1.54
                 Boron, mg/L                   0.38
                 Cadmium, mg/L                 <0.01
                 Total nitrogen as N, mg/L      20-25
                 Phosphorus as P, mg/L'3          6.2
                 a.  Based on  1976 tests, except as
                     noted.
                 b.  Based on  1973 tests.
                                TABLE  7-11
LOADING RATES  IN 1973  AND TYPICAL NITROGEN  UPTAKE  REQUIREMENTS,
               BAKERSFIELD LAND TREATMENT  SYSTEM [7]
Crop
Alfalfa
Barley
Corn
Cotton
Pasture grass
Liquid loading
rate, ft/yr
4.9
1.8
3.3
3.7
4.9
Nitrogen loading
rate, Ib/acre-yr
371
139
252
277
371
Typical
nltroqen uptake,
Ib/acro-yr
360-480
75
150
100
150-250
      1 ft = 0.305 m
      1 Ib/acre = 1.12 kg/ha
                                7-22

-------
                                TABLE  7-12

               EXISTING  CROP  YIELDS AND ECONOMIC RETURN,
                    BAKERSFIELD,  LAND  TREATMENT SYSTEM
                                      Typical      Economic
                 Crop    Yield, Ib/acre  price, $/lba  return,  $/acre
Alfalfa
Barley
Corn
Cotton
16 000
3 000-5 000
36 000-60 000
600-800
0.025
0.045
0.0075
0.35
400
135-225
270-450
210-280
                 a.  Based on 1973 prices.

                 1 Ib/acre =1.12 kg/ha
                 1 $/lb = $2.2/kg
                 1 $/acre = $2.47/ha
Management  of  water  has   become   a   problem due to lack of storage and
increasing  flows.  Ponding  of  excess  water has occurred on some areas of
the pastureland in winter.   Although flies  and mosquitos are attracted to
the  stagnant  water,  no diseases  have been traced to effluent use.   The
equalizing reservoirs and the storage  pond  for tail water are periodically
sprayed to control mosquito  propagation.
Public health regulations  for
are  such that the quality  of
of  primary  effluent.   No di
none  is  provided  at  the  two
barley  are  green  chopped (
Dairy   cows   are    not    all
nondisinfected  effluent   so
cattle  are  allowed  to both
and hay.
irrigation of fodder, fiber,
reclaimed water shall not be
sinfection of the effluent i
 treatment plants.  Normally
not harvested for grain) for
owed   to  graze  pastures
they are fed with green chop
graze pastures and be fed on
 and seed crops
 less than that
s required, and
  both corn and
 cattle fodder.
irrigated  with
 and hay.  Beef
 the green chop
     7.4.3  Proposed  System  Characteristics  and Design Factors
Although  primary  effluent   is   suitable  according  to  the  California
Department  of  Health,  the  Central  Valley Regional  Water Quality Control
Board  has  set  limits   of   40  mg/L on BOD and suspended solids prior to
forage  crop irrigation.   Their  rationale is that such an effluent can be
stored without causing a  nuisance and will reduce the potential for odors
in system management.
                                   7-23

-------
The   proposed   system  consists   of  an   upgrading  of  the  existing
preapplication  facilities and inclusion of a  concrete pipe distribution
system for continued surface irrigation of  crops.   City plant No.  1  will
be  abandoned  and  its  flow  redirected to-city  plant No. 2, where new
primary clarifiers and aerated lagoons will  be constructed. Chlorination
will  not  be  provided  since surface application to forage, fiber, and
seed crops does not require disinfection.


The 4 800 acre (1 944 ha) land area of the  proposed system will  be twice
that  of  the  existing  system  because the  principal  objective  of the
proposed  system  is  crop production rather than  land treatment.   Thus,
double  cropping  with  corn and barley is  proposed and this combination
requires  less  water  than  is  presently   applied.   A schematic  of the
portion  of  the  system  located within the limits of the existing  city
farm and an additional 320 acre (129 ha) parcel  northeast of the farm is
presented  in  Figure  7-8.   The  remainder of the system (not shown in
the  figure)  is  located  to the south, including 960 acres (389  ha) of
undeveloped land which will  be reclaimed for irrigation.
     7.4.4  Proposed System Operation
Flexibility  of  operation will  be provided by  storage reservoirs,  which
will  hold  flows during periods of low irrigation demand.   In addition,
automatically  operated  tail water  return  stations  will  control  runoff
from  irrigated  fields.   Outlets  from  the distribution  laterals will
consist  of  orchard-type  valves  which  are adaptable to  gated surface
pipe,  open  ditches  with  siphon  pipe,   or   direct flooding of  border
strips.   Telemetered alarms will continuously  scan the operation  of the
system  to  alert  the  operator  of  malfunctions at any  of the pumping
stations.
     7.4.5  Costs
City revenues from the lease of the existing  farm amount to about 20% of
the  operating  and  maintenance costs for the  two treatment plants [7].
Detailed  operating and maintenance costs for the existing farm were not
available.
The estimated construction costs for the proposed system on the basis of
summer  1977  construction startup are summarized in.  Table 7-13.   These
costs   do   not   include   land   acquisition   costs  or  engineering,
administration,  and legal expenses.  The City of Bakersfield will  lease
the  property  to  the  highest responsible bidder for management  of the
system,  and  the  city  will  be responsible only for  maintenance  of the
main pipeline and all pumping  equipment.
                                   7-24

-------
                 FIGURE  7-8

PROPOSED  WASTEWATER IRRIGATION  SYSTEM,
        BAKERSFIELD, CALIFORNIA
                   DISTRIBUTION DITCH
^^^F
                                           0    1 000  2000 3000

                                           SCALE        FEET
                                         LEGEND
                                           MAIN DISTRIBUTION LINE
                                           AND OVERFLOW STRUCTURE


                                           LATERAL

                                           TA ILWATER RETURN STATION
                                           AND PIPELINE
                                           PUMPING STATION
 , , TO  ADDITIONAL PROPERTIES (2100ACRES)
                      7-25

-------
                                TABLE  7-13

                      ESTIMATED CONSTRUCTION COSTS,
                  PROPOSED WASTEWATER  IRRIGATION SYSTEM,
                         BAKERSFIELD,  CALIFORNIA3
               Land reclamation and site development       $ 1 126 000

               Storage and equalizing reservoirs            5 385 000

               Distribution pipelines                     4 697 000

               Distribution pumping stations                 621 000
               Tailwater return systems                    513 000

               Bonds and insurance                        154 OOP

                 Total                              $12 496 000
               Construction costs, $/gal of capacity15           0.66

               a. Based on summer 1977 construction startup.
               b. Based on 19 Mgal/d average flow.

               1  $/gal  = $3.785/L
               1  Mgal/d = 43.8 L/s


7.5  San Angelo, Texas


     7.5.1   History


San  Angelo,   a   city of about 65 000  in  west central Texas,  has treated
its  wastewater   by  primary   sedimentation followed by  land  application
since  1928.   The system was operated  at  one site  for the  first 30 years
and  has  been operated at  the present site for 18 years.   Pressure from
development   around  the first site led to its abandonment in 1958.  The
present  slow rate  system consists   of  630  acres   (255 ha) of city-
owned  pasture  and  cropland  irrigated  by the border  strip  method (see
Table 7-14).   Preapplication  treatment   will  soon  be  upgraded  from
primary  to  secondary to meet  state  requirements  for wastewater  irriga-
tion of areas accessible to the  public.


     7.5.2   Project Description


Wastewater    is    currently   given  primary  treatment  prior  to  land
application.   The  effluent  can  be   used  directly  to   irrigate  the
pastureland,   shown  in  Figure  7-9,   or  it can be directed through four
holding  ponds.    The   detention time  in  the ponds at an average flow of
5.8 Mgal/d   (254 L/s)   is   about  30 days.   The   330 acres  (134 ha) of
pasture receive  somewhat more  effluent annually than the 300  acres  (121
ha) of cropland, which  is rotated between oats, rye, and grain sorghum.
                                    7-26

-------
                                   TABLE 7-14
                                 DESIGN FACTORS,
                               SAN ANGELO,  TEXAS
            Type of system
            Avg flow,  Mgal/d
            Type of wastewater
            Preapplication treatment
            Disinfection
            Storage
              Capacity, Mgal
              Time, d
            Field area, acres
            Crops

            Application technique
            Routine monitoring
            Buffer zones
            Application cycle, d
              Time on
              Time off
            Annual application rate, ft
            Avg weekly application rate, in.
            Avg annual precipitation, in.
            Avg annual evaporation, in.
            Annual nitrogen loading, Ib/acre
            Operation  and maintenance
            costs, 4/1 000 gal
Slow rate
5.8
Domestic and industrial
Primary
No

174
30
630
Coastal Bermuda grass, fescue,
oats, rye, and grain sorghum
Surface (border strip)
Yes
No

1
10-14
10.3
2.4
18.6
60
800

0.9
            1  Mgal/d = 43.8 L/s
            1  acre = 0.405 ha
            1  ft = 0.305 m
            1  in. = 2.54 cm
            1  Ib/acre =1.13 kg/ha
            1  4/1 000 gal = 0.264 
-------
                                FIGURE 7-9


                      SLOW RATE LAND TREATMENT SYSTEM
                           AT SAN ANGELO, TEXAS
                                                        SEEPAGE

                                                         CREEK
                                                         NO.  1
                  HOLDING

                   PONDS
        xxxxxxx
        XXXXXXXXXXXXXXXXXX
        XXXXXXXXXXXXXXXXXX
        XXXXXXXXXXXXXXXXXX
        XXXXXXXXXXXXXXXXXX
        XXXXXXXXXXXXXXXXXX
        XXXXXXXXXXXXXXX
        XXXXXXXXXXXXXX
        XXXXXXXXXXXXXX
               XXXXX
                            XXXXXXXN\S
                            XX
                            XXXXXXXXXX
                            XXXXX
                            xxxxxxxxxx
                            xxxxxxxxxx
                            xxxxxxxxxx
                            xxxxxxxxx
                                 xxxx
                            xxxxxxxxx
                            xxxxxxxxx
                            xxxxxxxxxx
                            xxxxxxxxxx
                                      SEEPAGE
                                       CREEK

                                       NO. 2
xxxxxxxxxx^
xxxxxxxxx
           STORAGE POND
                                         WELL NO.  2



                                               IRRIGATED AREAS




                                               STORAGE FACILITIES
     7.5.4  Operating Characteristics and Treatment Performance
The  pasture!and  is  planted in coastal Bermuda grass  that is both grazed
by  beef  cattle   and  harvested  as  hay.   Grazing   rights are sold to
cattlemen  and  the  hay,  shown in  Figure 7-10,  is sold to the public by
the bale.  The  oats,  rye, and sorghum are used for cattle feed.
The  wastewater  is  applied by the border strip method as shown in Figure
7-11.   The borders vary in width and follow the  slope of the land.  The
principal soils  are Angelo and Rio Concho clay loams.



The  treatment   performance can be estimated by comparing the quality of
the applied wastewater to the quality of groundwater that emerges out of
                                   7-28

-------
                      FIGURE 7-10




    COASTAL BERMUDA GRASS HAY AT SAM ANGELO, TEXAS
                      FIGURE 7-11




BORDER STRIP IRRIGATION OF PASTURE AT SAN ANGELO, TEXAS
                          7-29

-------
seepage  creek No. 1.  The treatment performance  data presented in Table
7-15  are for October 1973 [8].  The apparent nitrogen removal  of 52% is
for  an area currently in pasture that receives over 800 lb/acre-yr (900
kg/ha-yr).  The crops grown in that area in 1973  are unknown.
                               TABLE 7-15

                         TREATMENT PERFORMANCE,
                          SAN ANGELO,  TEXAS [8]
                                  mg/L
Constituent
BOO
Ammonia nitrogen
Nitrate nitrogen
Total nitrogen
Total phosphorus
Total dissolved solids
Pond
effluent
54.2
28.0
0.8
28.8
5.9
1 704
Seepage
creek No. 1
1.0
0.2
13.0
13.7
0.09
1 900
The  high  total  dissolved  solids  value  apparently does not adversely
affect  crop  growth.   The  pasture  that  is  grazed supports 10 head of
cattle per acre (25 head/ha) which is an  order of magnitude greater than
comparable  densities  for  conventional  irrigated  pasture  in central
Texas.
     7.5.5  Costs
Capital costs for the construction of the system in 1955 and purchase of
the  land  are  not  available.    In  1972,   the  value  of the land was
estimated  to  be  $500/acre  ($1  250/ha) [3].   The new activated sludge
plant,  which  will  have  a capacity of 8.5  Mgal/d (372 L/s),  will  cost
$4  million (April  1977). This  plant will be  capable of supplying efflu-
ent as  irrigation  water to nearby farmers.   The present land  treatment
system may be expanded when the  city can purchase additional  land in the
area.
Operations  require  three  farm  employees  and  a manager at a budget of
about $60 000 to $70 000/yr.  Grazing rights are sold at $5.50/month for
each  head of cattle.  The baled hay is  sold at  $1.50 to $2.00 per bale.
In all, the revenue from the farm amounts to $80 000 to $90 000/yr for a
net  profit  of  around  $20 000/yr.  Revenues amount to  3.8tf/l  000 gal
                                  7-30

-------
     7.5.6  Monitoring


Normal   monitoring  includes periodic analyses of groundwater in several
wells.   In October 1973, an intensive monitoring survey was conducted to
determine  the  effects of the land treatment system on the Concho River
[8].   The  findings  were  that  while  seepage  from  the  system  was
significantly  increasing  the  flow  of  the  river,  it  was  having a
negligible  effect  on the water quality.  A sample groundwater analysis
from the normal monitoring program is presented in Table 7-16.
                               TABLE 7-16

                     SAMPLE OF GROUNDWATER QUALITY,
                        SAN ANGELO, TEXAS [9, 10]
                                  mg/L
                     Constituent         Well No.  1  Well No. 2
Total dissolved solids
Total alkalinity as CaCOs
Total hardness as CaCOj
pH, units
Calcium
Magnesium
Sodium
Sulfate
Chloride
Bicarbonate
Iron
Phosphorus
Ammonia nitrogen
Nitrate nitrogen
Total nitrogen
- 1,659
352
1,080
7.3
192
146
130
• 140
596
429
2.7
0.015
0.0
9.0
9.1
1,628
394
676
7.3
162
66
265
120
500
481
0.1
0.025
0.0
22.3
22.4
     7.5.7  Long-Term Effects Research
Research  on  the  chemical  and  microbiological effects of 18 years of
operation  is  being conducted by researchers at Texas A & M University.
The  2  year  effort  is expected to be finished in 1977.  Sampling will
include  soil, plant tissue, wastewater, groundwater, and water emerging
as seeps.  The heavy metals, nutrients, and organics will be measured in
the water and soil samples.  Crops within specially fenced areas will be
checked for yields and tested for nutrients and accumulation of metals.
                                 7-31

-------
7.6  Muskegon, Michigan


     7.6.1   History and Objectives
The  need  for  an  alternative  wastewater  management  program  for  the
Muskegon  County  area  became  apparent  in   the   late 1960s  because of
deterioration  in  the  water quality  of local  surface waters.  Fourteen
municipalities and five major industries were  required to achieve an  80%
phosphorus  reduction  and produce  effluent that would not result in  the
degradation of the water quality of Lake Michigan.


Areawide  solutions  were explored  and the most cost-effective solution
was to divert all the wastewater discharges from surface waters and make
use  of  undeveloped  land as a major  component of  an  areawide treatment
system.   The  decision  to  undertake  such a plan was based  in  part on
economics  and in part on a commitment to recycle  nutrients as resources
rather than discharge them to the environment  in a  nonbeneficial  manner.
Construction of the facilities commenced in 1972 and operation was begun
in  stages  starting  in May 1974.   The first  full  year of operation  was
1975.
     7.6.2  Project Description and Design  Factors


The  Muskegon  County  Wastewater  Project   consists   of two  independent
systems:   the Muskegon Project and the  smaller  Whitehall  Project.   Both
systems make use of the slow rate process of land treatment.   Because  of
the  much  larger  size  and  quantity   of  information available  for the
Muskegon  Project,  this section will be limited to a  discussion  of  that
system.   A  summary  of  the  principal design  factors for the Muskegon
Project is presented in Table 7-17.


Industrial  wastewaters  discharged to the  system constitute  over 60%  of
the present flow.  The largest single discharger, S.D. Warren Company,  a
Kraft papermill, contributes approximately  15 Mgal/d  (0.7  m3/s) [11].


The treatment system consists of biological  treatment  in aerated  lagoons
followed  by  sprinkler  irrigation of  land on which corn is presently
grown.   While  there  are  many interesting features  of the  system, its
uniqueness  lies  primarily  in^the size of the  facility.  With a design
capacity  of  42 Mgal/d  (1.8 m /s) and over 5 000  acres (2 025 ha)  of
land  under  irrigation,  it  is  the  largest operating facility in the
United  States  designed  specifically for  land  treatment of  wastewater.
Other  features  include  the low overall operation costs. During  1976,
crop revenues offset 60% of the total operating  costs  of the  system.
                                 7-32

-------
                               TABLE 7-17
                  DESIGN  FACTORS, MUSKEGON PROJECT,
                          MUSKEGON, MICHIGAN
      Type of system
      Avg flow, Mgal/d
      Type of wastewater
      Preapplication treatment
      Disinfection
      Storage
Slow rate
28.5
Domestic and industrial (papermilli
Aerated lagoons
As required
Capacity, Mgal
Time, d
Field area, acres
Crops
Application technique
Routine monitoring
Buffer zones
Application cycle
Time on
Time off
Annual application rate, ft
Avg weekly application rate, in.
Avg annual precipitation, in.
Avg annual evaporation, in.
Annual nitrogen loading, Ib/acre
Capital costs, $/gal of capacity^
Operation and maintenance costs, 4/1 000 gal
5 323
187
5 350
Corn and rye grass
Sprinkler (center pivot)
Yes
Yes
Varies
Varies
Varies; 1-9, avg 6
3.0
32
30
130
1.01
12.5
      a.  Includes transmission, preapplication treatment, storage, distribution
         system, and underdrainage.
      1 Mgal/d = 43.8 L/s
      1 acre = 0.405 ha
      1 ft = 0.305 m
      1 in. = 2.54 cm
      1 Ib/acre =1.13 kg/ha
      1 $/gal = 3.785/L
      1 4/1 000 gal = 0.264 «/m3
A  plan  of the facilities is shown  in  Figure 7-12.   Incoming wastewater
first  enters one of  three 8 acre  (3.2 ha) aerated  lagoons, which may be
operated  in  parallel   or series.   From the treatment cells, wastewater
enters   the  two  850  acre  (344  ha) storage lagoons shown.  A  separate
settling  pond  is  also  provided   which  can   serve as a bypass to the
storage  lagoons.  During the irrigation season  (April through November),
water  for  irrigation   is drawn from either the storage lagoons or from
the  settling  pond   into a 14 acre (5.6 ha) outlet lagoon.  The treated
effluent  released from the outlet  lagoon can be chlorinated in  a mixing
chamber  prior to delivery via open  channels to  the  two main distribution
                                    7-33

-------
                              FIGURE  7-12

             MUSKEGON PROJECT  LAND  TREATMENT  SITE PLAN
                                                             APPLICATION
                                                             AREAS
          AERATED LAGOONS

          SETTLING POND

          OUTLET LAGOON

          CHLORINATION FA Cl I LTY

          DISTRIBUTION PUMPING STATIONS

          DRAINAGE PUMPING  STATIONS

   •      DRAINAGE WELLS

	*._ —  MAIN  DRAINAGE TILES

	to-	  DRAINAGE DITCHES
                                   7-34

-------
pumping stations.  These pumping stations deliver the wastewater through
a  series  of  buried  pipes  to  the  irrigation equipment.   Because  of
bacteria  die-off  during  the  long storage period,  chlorination is not
required at all times to meet discharge requirements.


Wastewater is applied to the land by 54 center pivot  irrigation machines
which  utilize  low  pressure  nozzles  and roll  on pneumatic tires (see
Figure 7-13).  Vertical  turbine pumps at two main pumping stations  dis-
charge to an asbestos-cement pipeline distribution network.  Major design
data for the distribution system are presented in Table 7-18.
Soil types at the application site include sandy soils with infiltration
rates from 5 to more than 10 in./h (12.7 to 25.4 cm/h), loamy soils  with
rates  from  2.5 to  10 in./hr  (6.4 to  25.4 cm/h),  and clay soils  with
rates  ranging  from 0.02 to 2.5 in./h (0.05 to 6.4 cm/h).   The majority
of  the  soils,  however, are sands and sandy loams.   The maximum design
application rate is 4 in./wk (10 cm/wk), which includes an  allowance for
0.74 in./wk (1.9 cm/wk) of precipitation.
A  combination  of  drainage tiles, drainage wells, and natural  drainage
collects  the  subsurface  water and discharges it to adjacent receiving
surface  waters.   The  majority  of the site is underlain with drainage
tiles  at approximately 500 ft (153 m)  intervals  and  from  5 to  8 ft
(1.5 to   2.4m)   deep.    The   laterals,  constructed  of  perforated
                             FIGURE 7-13

              CENTER  PIVOT BOOM WITH LOW PRESSURE NOZZLE,
                           MUSKEGON PROJECT
                                   7-35

-------
 polyethylene  filtered   by  fiberglass  socks,  conduct the water  to main
 concrete  drainage   pipes.   The  concrete pipes  carry the water  to open
 ditches  which  in   turn  discharge  to two  receiving streams.  Drainage
 tiles  were largely installed using a continuous plow machine as shown in
 Figure 7-14.
                                TABLE 7-18

                      DISTRIBUTION SYSTEM DATA  [12]
                             MUSKEGON PROJECT
                 Pumping

                  No. of vertical turbine pumps           17

                  Peak capacity, Mgal/d                  91.7

                 Piping size range, in.                   8-36

                 Center pivot irrigation rigs

                  No. of rigs                         54

                  Radius, ft                         700-1 400

                  Coverage range, acres                  35-141

                  Operating pressure, Ib/in.2             35-84
                                    2
                  Nozzle pressure, Ib/in.                3-10

                  Application rate (continuous operation)

                    in./h                            0.0239
                    in./wk                            4.0

                 Application season, months               8
                 1 Mgal/d = 43.8 L/s
                 1 in. = 2.54 cm
                 1 ft = 0.305 m
                 1 acre = 0.405 ha
                 1 lb/in.2 = 0.69 N/cm2
     7.6.3   Operating Characteristics and Performance


Irrigation   with  wastewater   at  Muskegon  commenced  in  May 1974,  and
numerous   temporary  startup   problems  were  encountered.   Most of  the
problems,   such as dike damage,  breaks in irrigation  pressure pipes,  and
electrical    cable   failures,    have  been   resolved.    A  persistent,
significant  odor  problem  occurred  at  the  treatment  site  and   was
attributed   to  the high volume  of papermill waste.   The inlet structure
has been modified to reduce the  release of odor.
An  operational   problem  was  the  plugging of the  irrigation rig nozzles
with  a  mixture  of  sand   and  weeds, which are  blown into the storage
lagoons  and  main  irrigation ditches.  During the  first two irrigation
seasons,   ten  full-time  "nozzle   cleaners" were  hired in an attempt  to
minimize   plugged nozzles.   Even with this effort, the degree of uniform
                                    7-36

-------
water  application  was  not  acceptable.    To   alleviate   this  problem,
settling  basins and screening systems have been installed  ahead of  both
irrigation pumping stations.
                            FIGURE 7-14

                   INSTALLATION OF DRAINAGE TILES,
                          MUSKEGON PROJECT
Another  operational problem during the first season was downtime due to
the  irrigation rigs becoming stuck in soft, wet soil  in one area.  This
problem  has  been greatly alleviated by increasing tire size from 11 by
24 in. to 14.9 by 24 in. (28 by 60 cm to 38 by 60 cm).   To further alle-
viate the problems of stuck rigs, machine speed has been doubled [12].
In  1975, 4 700 acres (1 900
was  planted  in  corn  and
wastewater.   The  remaining
grass.   Total  wastewater
(254 cm/yr) per field, with
to  75 in./yr  (127 to  190
grain  from  various  fields
1975 season are presented in
 ha)  of the 5 400 acres (2 182 ha)  irrigated
 irrigated with up to 4 in./wk (10  cm/wk)  of
  700 acres  (283 ha)  was  fallow  or in rye
applied  ranged from zero to over 100 in./yr
the majority of the fields receiving from 50
cm/yr) [13],   Representative yields of corn
 at the Muskegon land treatment site for the
 Table 7-19.
                                   7-37

-------
                                TABLE 7-19

                   REPRESENTATIVE YIELDS OF  CORN  GRAIN,
                          FOR VARIOUS SOIL TYPES,
                  MUSKEGON LAND TREATMENT SITE, 1975 [13]
Wastewater
application,
Field soil type in./yr
Rosconnton sand
Rubicon sand
AuGres sand
Roscommon sand
Granby loamy sand
Rubicon sand
AuGres sand
Roscommon sand
Project average
57
106
59
69
14
93
14
14
54
Supplemental
nitrogen
fertilizer,
lb/acre-yr
65
63
70
40
27
44
10
0
44
Corn grain
yield,
bu/acre-yr
90
83
71
69
61
53
36
31
60
               1 in./yr =2.54 cm/yr
               1 Ib/acre-yr = 1.12 kg/ha-yr
               1 bu/acre-yr = 2.47 bu/ha-yr
The  wastewater  provides  an  adequate amount of phosphorus  and  potassium
for  the  corn   crop  [13].    However,  the low levels of  nitrogen  in  the
wastewater would not  be  adequate without  supplemental additions.   In  the
sandy   soil, there  is little  organic nitrogen and even less in  a soluble
form  usable  by plants,   as  sandy  soils do not  retain much  nitrogen.
Therefore, during the 2  months  of the 6 month irrigation  period in which
the  corn  is  actively  growing,  it  is  necessary  to  inject nitrogen
fertilizer  into the wastewater on a daily basis.  It is important that
the  application rate  of  the soluble nitrogen be adjusted  so that  the
corn  plants  absorb   and   use  all of the available nutrients as fast as
their  metabolism   permits.   From 0 to 89 Ib/acre-yr (0 to  100  kg/ha-yr)
of  nitrogen  fertilizer was  added  to  the different irrigated fields,
depending  upon  the   amount  of wastewater applied and crop  requirement
needs.
Corn planted in 1976 yielded an average of 81 bu/acre-yr  (200 bu/ha-yr),
significantly greater than the 45 to 50 bu/acre-yr (111 to 123 bu/ha-yr)
average corn grain yield on operating farmland in Muskegon County.  This
is  quite  remarkable  in  light  of  the  fact  that  most soils at the
treatment  site  are  very  poor  and  that wastewater renovation is the
primary  purpose  of  the  system.  The agricultural productivity of the
Muskegon  land  treatment system has steadily increased over its first 3
years  of  existence,  as  shown  in  Table  7-20.  Sale  of the corn has
proceeded with the grain commanding full market value.
                                  7-38

-------
                                TABLE 7-20

                   INCREASED AGRICULTURAL PRODUCTIVITY,
                     MUSKEGON LAND TREATMENT SITE [13]
                                           1974   1975 1976
Corn yield, bu/acre-yr
Land treatment site
Muskegon County average
Gross crop revenue, $ millions

28
55
0.35

60
65
0.7

81
45-50
1.0a
                  a.  Estimated.

                  1 bu/acre-yr = 2.47 bu/ha-yr
 The   entire   Muskegon wastewater treatment operation is being  handled  by
 40 full-time  people  and an  additional   part-time labor force of  up  to  10
 workers.   A   part of this  work  activity  is associated with  the  Muskegon
 EPA   Research  and   Development   Grant.    The   normal   staffing   of the
 treatment  operation  during   the  day  shift is 2 people on  the  northern
 irrigation  rigs  and  2 people  on  the  southern  irrigation rigs with
 another  2  people   providing  maintenance  as  needed  [11].  The other 2
 shifts are staffed with 1 person per  shift.


 The   average   treatment  results  for 1975 are  presented in  Table  7-21.
 BOD,  suspended  solids,  and  phosphorus  levels are  well   below the
 discharge  permit requirements,   which   are 4  mg/L  for BOD, 10  mg/L for
 suspended solids, and 0.5 mg/L for phosphorus.


      7.6.4  Costs
The  construction  cost for the Muskegon wastewater treatment system was
$42.7  million,  of  which $12.0 million was for collection  (force mains
and sewer lines) and transmission  (pumping and lift stations) [13].  The
net  operating costs for the total wastewater treatment system (Muskegon
and  Whitehall  sites)  incurred   during the 1975 season was $1 232 000.
Gross  operating  costs  by  system  component  and  revenues gained are
presented in Table 7-22.
Operating  experience  based on observations of storage lagoon treatment
performance  has  shown  that the actual biological treatment system was
overdesigned.   It  has  been  demonstrated that proper treatment can be
obtained  by  running a smaller percentage of the aerators [12].    This
has resulted in  reduced operating costs for  aeration.  As   additional
                                  7-39

-------
cost-effectiveness measures  of this  nature  become apparent.
reduction in net operating costs can be expected.
further
                               TABLE 7-21

                    SUMMARY OF TREATMENT PERFORMANCE,
                         1975 AVERAGE RESULTS,
                         MUSKEGON PROJECT [ll]a
Parameter
BOD
pH, units
Specific conductance, ymhos
Total solids
Suspended solids
COD
TOC
Ammonia-N
Total Kjeldahl nitrogen
Nitrate-N
Total P
Chloride
Sodium
Calcium
Magnesium
Potassium
Iron
Zinc
Manganese
Total col i forms,
Fecal col i forms,
colonies/100 nt
Fecal streptococci,
colonies/100 ml

Influent
205
7.3
1 049
1 093
249
545
107
6.1
8.2
Trace
2.4
182
166
73
14
n
0.8
0.6
0.28




Average storage
lagoon effluent
13
7.8
825
691
20
118
38
2.4
4.5
1.1
1.4
154
144
58
16
9
1.0
0.11
0.16
100-1 2xl08
4-1 2xl06
2-3 8x10^

Drain tiles
1.2
599


11.6
0.29
2.2
60
42
72
23
2.6
7.7
0.01
0.20


-------
crop   characteristics.   Samples  are   taken for chemical and biological
analyses  once or  twice daily  at each  step of the treatment process.   On
a  weekly  basis,   a  total  of 2 883  samples are analyzed for  one of 25
wastewater  constituents [11].    In  addition,  groundwater  is  sampled
monthly  to  twice  yearly   from over  300 wells for  analysis [13].  This
massive  monitoring  program  requires   the  services of nine laboratory
personnel  and   the  results,   thus  far,  have been that no significant
effects on the groundwater  or  surface  water of the area have occurred.

                                  TABLE 7-22
                               OPERATING  COSTS
                    MUSKEGON  WASTEWATER  SYSTEM, 1975 [13]
                 Operating costs by component
                   Collection and transmission            $ 431  000
                   Aeration and storage                    191  000
                   Irrigation and drainage                 475  000
                   Farming                              474  000
                   Laboratory and monitoring                236  000
                   Other                                 77  OOP
                     Subtotal, Muskegon                  $1 884  000
                   Total, Whitehall                        62  OOP
                      Total, gross operating ,            $1 946  000
                 Revenues
                   Crop
                     Corn (4 500 acres x 60 bu x $2.58/bu)   $ 698  000
                     Wheat (270 acres x 10 bu x $3.10/bu)        8  000
                   Laboratory services                   	8  OOP
                     Total                            $ 714  000
                 Net operating cost                     $1 232  000
                 Unit operating cost, 
-------
lagoons,   storage, and sprinkler application of approximately 0.6  Mgal/d
(26   L/s)  in   a  wooded   area  (see   Table 7-23).  The  land application
portion of the  system has  been operated primarily as a means of  disposal
with   little  attention  given  to  either treatment performance or crop
production benefits.
                                  TABLE  7-23
                                DESIGN FACTORS,
                         ST.  CHARLES, MARYLAND  [3,  14]
              Type of system
              Avg flow, Mgal/d
              Type of wastewater
              Preapplication treatment
              Disinfection
              Storage
               Capacity, Mgal
               Time, d
              Field area, acres
              Crops
              Application technique
              Routine monitoring
              Buffer zones
              Application cycle
               Time on, h
               Time off, d
              Annual application rate, ft
              Avg weekly application rate, in.
              Avg annual precipitation, in.
              Avg annual evaporation, in.
              Capital costs, $/acrea
              Unit operation and maintenance
              costs, tf/1 000 gal
Slow rate
0.6
Domestic
Aerated lagoons
Yes

90
150
67
Wooded field (oak-pine)
Sprinkler (surface pipe)
No
Provided but not required

8-15
4-7
10
2-3.5
40
27
1  100
              a. 1966.
              1 Mgal/d = 43.8 L/s
              1 acre = 0.405 ha
              1 ft = 0.305 m
              1 in. = 2.54 cm
              1 $/acre = $2.47/ha
              1 
-------
surface   discharge   to   nearby   Zekiah  Swamp,  which  was  declared
environmentally unacceptable [3].


At  this  time,  the  Charles County Sanitary Commission and neighboring
Prince  George's  County  are  constructing  an interceptor and regional
treatment  plant  in  the Mattawoman Creek basin.  Plans (1976) call  for
St. Charles to join this system when completed, abandoning this site.


     7.7.2  Design Factors


The  preapplication  treatment originally consisted of an oxidation pond
system  covering  approximately  10  acres  (4  ha).  The combination of
preapplication  treatment  and  storage  lagoons now totals 40 acres  (16
ha),  and  six  floating aerators have been added to the influent cells.
Effluent quality from the lagoons averages about 40 mg/L BOD and 75 mg/L
suspended solids [15]. The effluent is then chlorinated to 20 MPN/100 ml
fecal coliforms (maximum allowable by State of Maryland).
The  land  application  system  consists  of 11 woodland plots which are
sprinkled   independently.    Because   wastewater   disposal   has  been
emphasized over treatment or tree production, only enough field area has
been  developed  to  preclude  ponding  and  runoff.   The plots receive
differing  application  rates,  depending  on  their ability to take the
water.
Aboveground  aluminum  pipe  is used for the distribution system.  The 6
in.  (15  cm)  diameter distribution mains are designed to discharge the
effluent   when  pressure  is  released,  thus  providing  cold  weather
protection.   The  2  in.  (5 cm) laterals are supported above ground so
that  they  will  drain back into the mains; this appears to have caused
problems  in  that  they  are  easily  knocked  over by deer.  Sprinkler
spacing  is  mostly  90  by  80  ft (27 by 24 m), which seems to produce
adequate   distribution   coverage   at   40 lb/in.2  (28  N/cm2).    The
sprinklers  are  primarily  the  impact type, although it has been found
that the stationary umbrella-type sprinklers reduce tree icing.
Buffer  zones  were  not  specifically required for the system, although
adequate  buffering is provided by the secluded nature of the site.   The
nearest  structure  is  approximately  0.5 mile (0.8 km) and the nearest
well is approximately 1.5 miles (2.4 km) [3].
     7.7.3  Operating Characteristics


The  system  has  continued  to  perform  adequately  for  the  purposes
originally  intended.   Operation  is  straightforward  and  requires  a
                                   7-43

-------
minimum  of control.  A crew of two workers  and  a supervisor operate  the
system  in  addition to their other duties,  and  usually visit the  site  3
to  5  times  per  day.   Pumps  and  distribution  lines  are  manually
controlled.   Decisions  regarding  application   periods  and cycles  are
based on visual  appearances of the fields.


The  groundwater  table  has  risen significantly throughout most  of  the
site and is at or near the surface in many areas [15].   In many  of these
areas,  the  original   tree  species have been  replaced by pokeweed as  a
result of the high groundwater.
     7.7.4  Monitoring Program
Operational  monitoring  of  the  lagoon  systems  at St.  Charles  has  been
reported,  but  the  land application portion  of  the system has  not  been
closely  monitored.   A  research  project  is currently being conducted
through   a   combined   effort   by  the  Departments   of  Agricultural
Engineering,  Agronomy,  Botany, and Civil  Engineering  at the University
of Maryland [15].  The study program hopes to  provide information  on the
fluctuation  of  groundwater  levels,  the  effects  on  water quality in
groundwater and nearby water courses, the fate of materials applied, and
the effects of vegetation.
7.8   Phoenix, Arizona


     7.8.1   History
Rapid  infiltration of municipal  wastewater at  Phoenix,  Arizona,  started
in 1967 when the U.S. Water Conservation  Laboratory,  in  cooperation  with
the Salt River Project and the City of Phoenix,  constructed the Flushing
Meadows  experimental  pilot  project.   The Flushing   Meadows   project
demonstrated  the  feasibility  of  renovating   secondary  effluent   for
unrestricted  use  for irrigation and recreational  purposes.  Uastewater
was  applied  to  the  rapid infiltration basins to evaluate the  quality
improvement  of  the  effluent  as  it moved   through   the soil  and the
hydraulics  of  the  groundwater  recharge  system.  The effect of basin
management  on  infiltration  rates  was   examined   by   altering  surface
conditions  and  flooding  schedules.  The results  for the first  5 years
are  well  documented [16, 17].    Operation of  the  project is continuing
and reports on the second 5 year study period will  be prepared in 1978.


The  23rd  Avenue  Project, a large scale rapid infiltration system, was
designed  based  on  engineering criteria developed at Flushing Meadows.
This  project,  constructed  in  1974, is  described  in the sections which
follow.   Design  factors  for  both  the  Flushing Meadows and the  23rd
Avenue Project are presented in  Table 7-24.
                                  7-44

-------
                                TABLE  7-24

                              DESIGN FACTORS,
                             PHOENIX,  ARIZONA
                                23rd Avenue Project
Flushing Meadows
Type of system
Avg flow, Mgal/d
Type of wastewater
Preapplication treatment
Disinfection
Storage
Field area, acres
Crops
Application technique
Routine monitoring
Buffer zones
Application cycle, d
Time on
Time off
Annual application rate, ft
Avg annual precipitation, in.
Avg annual evaporation, in.
Annual nitrogen loading,
Ib/acre
Rapid infiltration
13
Municipal
Secondary
Yes
Not required
40
None
Surface (basin flooding)
Yes
No
3-21
3-21
364
7
70
35 400
Rapid infiltration
0.6
Municipal
Secondary
Yes
Not required
1.9
None3
Surface (basin flooding)
Yes
No
4
10-20
365
7
70
35 400
       a.  Several vegetated basins were experimented with, but results
          were inconclusive.

       1 Mgal/d = 43.8 L/s
       1 acre = 0.405 ha
       1 ft = 0.305 m
       1 in. = 2.54 cm
       1 Ib/acre =1.12 kg/ha
     7.8.2   Purpose
A  need  to   supplement  the present  water resources in  the  Phoenix area
exists.   The  purpose  of the 23rd Avenue Project is to demonstrate the
feasibility   of  rapid infiltration on  a scale that could partially meet
this  water   need.    If  the  initial   demonstration  project  shows that
wastewater   can  be economically  renovated, the system could be expanded
to  reclaim   all   of  the  effluent   discharged  in the  Phoenix area.  A
significant   portion of the treated flow would be used for nuclear power
plant  cooling   water.   The rest could be made available for  irrigation
and  an extensive aquatic park development (Rio Salado Project) proposed
along the Salt  River channel.
                                     7-45

-------
     7.8.3  Project Description
The  rapid  infiltration site is located  on  the  north  side  of  the  bed  of
the  Salt  River and east of 35th Avenue.  The layout  of  the 23rd  Avenue
Project  is  shown  in  Figure  7-15.   Secondary  effluent  from  the  23rd
Avenue  wastewater  treatment  plant flows through a concrete  channel  to
the  site.   The  soil  profile  at  the  site  is similar  to the  Flushing
Meadows site, consisting of loamy sands,  sand, gravel,  and  boulders  to a
depth  of  over  200 ft (60 m) [16].  On  the basis of  results  learned  at
that  project,  infiltration  rates  of at least 2.5 ft/d (76  cm/d)  were
expected  [16].   Initially,  the effluent was routed  through  an 80  acre
(32  ha)  oxidation  pond before application to  the infiltration basins.
However, the extra detention time in the  oxidation pond (approximately 4
days)  stimulated  dense  algae  growths  in the effluent applied  to the
basins  and  reduced the average infiltration  rate to  about 0.5  ft/d (15
cm/d).   The  algae  remain  in  suspension  and accumulate on the basin
bottom  as  a  cake.  The algae cake does not  decompose or  shrink  during
drying   and,  consequently,  the  infiltration  rate   is  not  restored
significantly  when  flooding is resumed.  Pilot studies  have  shown  that
the  infiltration  rate  can  be  expected   to   at least  double  when the
oxidation  pond  is  bypassed,  as  shown  in  Figure 7-15,  and secondary
effluent is applied directly to the basins.


At  the  time  of  the  site  visit  (1976),  there was  no reuse  of the
renovated  water  taking  place.   The electric  rate for pumping the
renovated  water  initially was higher than  that of the local  irrigation
district,  thus  economically  prohibiting its use. The  City  of Phoenix
has  negotiated  with  the local power company to  lease the wells  to the
irrigation  district so that it can take  advantage of  the lower  electric
rate.   Resolution of this problem has made  the  costs  of  renovated water
competitive with those of native groundwater sources.


     7.8.4   Design Factors


At  the time when the 23rd Avenue project is in  full operation,  about  13
Mgal/d  (0.57  m^/s)  of  secondary effluent will  be applied to  the  four
rapid  infiltration  basins.  The renovated  water  will  be recovered  by a
series  of three 24 in. (60 cm) diameter  wells (1  existing  and 2 future)
equipped with electric driven pumps of 3  000 gal/min (189 L/s) capacity.
The  static  water table depth is about 80 ft  (24  m).   The  first well  is
200 ft  (60 m)  deep  and perforated from 100  to 120 ft~(30 to 36  m).   A
pump  discharge  and collection piping system  will be  constructed  to the
point  of  reuse.   Two  6 in. (15 cm) diameter  observation and  sampling
wells have been constructed, one each on  the north and south side  of the
rapid  infiltration  basin.   The wells will be  used to sample renovated
water  quality  and  monitor the groundwater level. The  project will  be
operated  so  that the groundwater level  will  be the same as that  in the
aquifer  adjacent  to  the project to preclude the movement of renovated
water away from the site.
                                  7-46

-------
                                  .FIGURE  7-15

                           LAYOUT  OF THE  23RD AVENUE
                   RAPID  INFILTRATION AND RECOVERY PROJECT
                                 PREAPPLICATION TREATMENT
                                 20 Mgal/d SECONDARY
                                 EFFLUENT FROM 23rd AVE
                                        STP



'





—
^3
'O
CD
C-J
LU
CO
UJ
' OC
O
^















_l
UJ
z
^(
E
0
H-
Z
UJ
3
_J
U.
u.
Ul







OXIDATION POND
OVERFLOW














, 1200
ft



^•^


1
BYPASS LEVEE
TO BE .^
CONSTRUCTED — -"^

80 acre
OXIDATION POND







^








lit . «
/ 1
t t 1
INLET
STRUCTURE 	 	

MONITORINGx
• ELL 5








	 13 Mgal/d
-^"^ BYPASSEfl TO RAPID
INFILTRATION BASINS






1
/4-10 acre RAPID
/INFILTRATION BASINS
* 1 * /
_ju


©



\_ 4


CD


/
INFILTRATION \ \ ]
k j
D

3 ©

D
i
i
BASIN OVERFLOW /
/
u /

-MONITORING
(7) Cf WELL
o
o
en
i
,
J
.300 ,
ft
T nnn osl/niin^' — ^^ MHA •»•>««» •
1  acre = 0.405 ha
1  ft = 0.305 m
1  Mgal/d = 0.043 m3/s
1  gal/min = 0.063 L/s
                   RECOVERY  WELLS  AND
                   COLLECTION  PIPING
                                                                   PROPERTY  LIMITS
                                       7-47

-------
     7.8.5  Operating Characteristics and Performance
When  the  23rd Avenue Project becomes fully operational,
various  wastewater  cycling  schedules will be studied.
dry-up periods ranging from several  days each to several
be  employed.    During inundation,  a constant depth  of 1
1.0m)  will   be  maintained.    Inflow  and  outflow will
evaluate  infiltration  rates   in each basin.  Basins wil
the  end of inundation periods into the next basin to be
the  dry-up  period  can  start  immediately.   One   of
structures to the infiltration basins is shown in Figure
 the effects of
 Inundation and
weeks each will
to 3 ft (0.3 to
 be measured to
1 be drained at
flooded so that
the  four inlet
7-16.
                               FIGURE  /-16

         INLET  STRUCTURE,  23RD  AVENUE  PROJECT, PHOENIX, ARIZONA
The unconfined groundwater table occurs at a depth of 60 to 80 ft (18 to
24  m)  beneath  the  site and is continuous to a depth of 230 ft (69 m)
where  a clay layer may be located.  The percolated wastewater will  move
toward  the  recovery  wells at the center of the basins.  The two outer
basins  will  be  inundated  while  the two inner basins are drying, and
vice-versa.   This  will provide travel distances in the range of 100 to.
500  ft  (30  to 150 m) and 400 to 900 ft (120 to 300 m) which may yield
two different qualities of reclaimed water.
                                   7-48

-------
By  pumping   only   as  much  reclaimed  water  as  has  been  infiltrated,
equilibrium   should  be established so that no flow between  the recharge
system  and  the  native groundwater takes place.  The  equilibrium will  be
checked   by   measuring  the  water  levels  in the observation  wells.   A
schematic  of the   infiltration  and  the  recovery  process   is  shown
in Figure 7-17.
The renovated water from the one existing recovery well  has  been sampled
and  analyzed   to   determine  the  performance  of the  system.   Measured
levels  of   BOD,   SS,  and fecal  coliforms have always been far  below the
specified   limit   for  unrestricted irrigation and recreation use and the
state  health   department  has  certified  the renovated water  for these
purposes.    Data   on  the  quality of renovated water at the 23rd Avenue
Project are presented  in Table 7-25 [18].
                                TABLE 7-25

                         RENOVATED WATER QUALITY
            THE  23rd AVENUE PROJECT IN PHOENIX, ARIZONA  [18]
                                                              a
                        Constituent                Average3


                     Suspended solids                0.8

                     Nitrate nitrogen                6.7

                     Ammonia nitrogen                0.1

                     Phosphorus                    0.16
                     Fluoride                      0.7

                     Boron                        0.5

                     Total dissolved solids          910.0

                     Fecal coliforms, colonies/100 mL    0-30


                     a.  mg/L unless otherwise noted.
     7.8.6  Monitoring  Program


In  addition  to   the quality and level  of groundwater, the  direction  of
groundwater  movement   will   also  be  checked  by  monitoring  the  total
dissolved  solids   concentration in the observation wells.   If  no native
groundwater  enters the   project,  the  total  dissolved  solids of  the
reclaimed  water   should   be  approximately  the  same  as   that of  the
wastewater effluent.
Continuous  24   hour   samples will  be taken of the effluent  entering  the
infiltration  basins.    Characteristics of the secondary effluent of  the
23rd Avenue  Project   were  not available at the time of the site visit.
However,  the  secondary  effluent from the 91st Avenue activated sludge
                                    7-49

-------
--J
I
in
o
                                                              FIGURE 7-17


                                SCHEMATIC OF  THE 23RD AVENUE RAPID INFILTRATION AND RECOVERY  SYSTEM
                                                                   DISCHARGE  PIPELINE
                      GROUNDWATER
                      FLOW LINES

-------
renovated   water  from  the  Flushing   Meadows  project  are  shown in
Table 7-26.
     7.8.7  Other Research at the 23rd Avenue Project
A  special  objective of the 23rd Avenue Project is to determine how air
pressure  buildup  in the soil  beneath large infiltration basins affects
the infiltration rate.  The effect of basin size on air pressure buildup
beneath the advancing wet front in the soil will be studied by comparing
infiltration  rates  measured by two methods.  Measurements will be made
with  cylinder  infiltrometers  or  by  comparing  small inundated areas
within the recharge basin to the infiltration rate when the entire basin
is  inundated.  Piezometers have been installed to measure air pressures
down  to a depth of 40 ft (12 m).  Reductions in infiltration rates from
air  pressure  buildup have proved to be insignificant for small basins.
Additionally, the depth of water during inundation of the basins will  be
varied  to  reduce  or  increase hydraulic head to determine what effect
these factors have on infiltration rates.


The effects of the high algae loading on surface clogging are also being
studied  before  the  oxidation pond bypass channel is completed.  Also,
research is being conducted to determine whether inundation depth can be
used to limit algae growth.  Tensiometers have been installed to measure
the  increase  in  hydraulic impedance of the surface layer over time in
the infiltration basins.
     7.8.8  Other Research at Flushing Meadows
Research  at  Flushing  Meadows  has  dealt  with the fate of viruses in
wastewater  as  they  enter  the soil.  Secondary effluent and renovated
water  from  four  observation wells were assayed every 2 months in 1974
for  viruses during flooding periods.  The number of viruses detected in
the  sewage effluent averaged 2 118 per 100 litres.  However, no viruses
were  detected in any well samples.  These results indicate that viruses
are reduced by a factor of at least  104  (99.99%) during percolation of
the wastewater through 10 to 30 ft (3 to 9 m) of the basin soil  [19].


The emphasis of the most recent research at Flushing Meadows is aimed at
maximizing  nitrogen  removal.   Increased  nitrogen  removal  has  been
realized  by reducing the hydraulic loading rate to the basins and using
optimum  flooding and drying periods.  Preliminary results indicate that
by  reducing the annual  hydraulic  loading  to  the  basins  from 300 ft
(100 m)  to 173 ft (52 m), nitrogen removal increased to about 60% (from
30%)  and  phosphate  removal increased to 90% (from 70%).  These values
are from samples taken from a well  in the center of the spreading basins
at  a  depth  of  30 ft  (10 m).   The  application  schedule was 9 days
flooding and 12 days drying.
                                   7-51

-------
                             TABLE  7-26

           CHARACTERISTICS OF  SYSTEM  INFLUENT AND
RENOVATED WATER,  FLUSHING MEADOWS,  PHOENIX, ARIZONA [17]
Concentration, mg/L
Constituent
BOD
COD
Suspended solids
Total dissolved solids
Total organic carbon
Total nitrogen3
Ammonium nitrogen (NH/i'N)
Nitrate nitrogen (NOs'N)
Nitrite nitrogen (N02"N)
Organic nitrogen
Phosphate (P04)-phosphorus
Fecal coliforms per 100 itl
Vi ruses per 100 mL
PH
Boron (B)
Fluoride (F)
Sodium (Na+)
Calcium (Ca++)
Magnesium (Mg"1"1")
Potassium (K+)
Bicarbonate (HCO3)
Chloride (CT)
Sulfate ($04)
Carbonate (CDs)
Cadmium (Cd)
Copper (Cu)
Lead (Pb)
Mercury (Hg)
Zinc (Zn)
System
influent
15
45
20-100
1 100
20
36
30
1
2
3
10
106
2 118
7.6-8.1
0.75
4.1
200
82
36
8
381
213
107
0
0.008
0.12
0.082
0.002
0-19
Flushing Meadows
renovated water
0-1
15
0
1 100
5
25
5-20
0.1-71&
1
1
0.1-3C
Od
0
7.0
0.75
2.6
200
82
36
8
381
213
107
0
0.007
0.017
0.066
0.001
0. 035-0. 108e
       a.   Overall nitrogen removal  during sequences of long
           flooding and drying periods was about 30%.

       b.   Nitrate peaks occurred when flooding was resumed after
           long dry-up periods as a  result of incomplete
           denitrification.

       c.   Phosphate removal increased with the underground
           travel time.

       d.   Fecal coliforms were between 0 and 200 per 100 mL
           in water sampled at 30 ft below the basins.
           Renovated wastewater from a well 200 ft away from
           the basins had-a zero fecal coliform count.

       e.   High zinc level may have  been the results of using
           galvanized plumbing in sampling wells.
                                7-52

-------
7.9  Lake George, New York


     7.9.1  History
Lake  George, located in the eastern part of the State of New York,  is a
recreational  lake 32 mi (52 km) long and from 1 to 3 mi (1.6 to 4.8 km)
wide.   The discharge of any wastewaters, treated or untreated, directly
into the lake or into any tributary thereof has been strictly prohibited
for  at  least 90 years.  This has preserved the pristine quality of the
lake  which  is  still  used  as  a public drinking water supply with no
treatment other than chlorination.
By  the  late 1930s, Lake George Village, located at the southern end of
the  lake,  had  grown  large  enough  to require a wastewater treatment
plant.   Since  septic  tank  systems  had  been allowed, the regulation
restricting the discharge of wastewater into the drainage basin area was
interpreted  to  mean  surface  discharges.    Thus,  it was decided that
discharge into the soil would be a satisfactory means of disposal of the
treated effluent from the proposed wastewater treatment plant.
Although  most  of  the  Lake  George  watershed  is  underlain  by rock
consisting of  pre-Cambrian gneisses, a small natural  delta sand deposit
created  by  outwash  from  the  receding glaciers was discovered at the
southwest  corner  of the Lake George Village area.  Advantage was taken
of  this  mass  of  delta  sand  and  the wastewater treatment pi ant was
constructed   at   this  location  to  utilize  this  sand  as  a  rapid
infiltration  area  for  the secondary effluent.  The original treatment
plant  was  completed  and  put  into  operation in 1939 and has been in
continuous   operation  ever   since.   Design  factors  for  the  rapid
infiltration  system  are  presented  in  Table 7-27.   A view of a rapid
infiltration basin is shown in Figure 7-18.  During the winter ice forms
on the basin surface (Figure 7-19) and the applied wastewater floats the
ice and infiltrates into the sandy soil.
     7.9.2  Project Description
The  Lake  George Village wastewater treatment plant receives wastewater
from two force mains, one from the Village and one from the Town of Lake
George.   There are five pumping stations, including two located in town
which  lift  the  wastewater  approximately   200 ft   (60 m)  from  the
collection  point at the lake to the treatment plant.  Primary treatment
is  provided  by  one  circular Imhoff tank and two mechanically cleaned
circular  Clarigesters  (similar  to  Imhoff  tanks),  all  operating in
parallel.   Secondary  treatment consists of two  high-rate rotating arm
trickling  filters and one covered  standard-rate fixed nozzle trickling
filter.   The latter is used exclusively in the winter and is covered to
prevent  icing  of  the  sprayed wastewater.  Secondary sedimentation is
accomplished  by two rectangular and two circular settling tanks.  After
                                    7-53

-------
 secondary   sedimentation,   the unchlorinated effluent is passed  onto the
 natural  delta  sand   beds  for infiltration into  the soil.  At  present,
 there  are   14 north   and   7 south sand  beds.  Sludge from the secondary
 settling  tanks  is returned to the Clarigesters,  and digested sludge is
 applied  to  3 sludge   drying beds.  The general layout of the treatment
 plant  and  the location of the sand beds and sampling wells are  shown in
 Figure 7-20.
                                  TABLE 7-27
                                DESIGN FACTORS,
                             LAKE GEORGE,  NEW  YORK
               Type of system
               Avg flow, Mgal/d

               Type of wastewater
               Preapplication treatment
               Disinfection
               Storage
               Field area, acres
               Crops
               Application technique
               Routine monitoring
               .Buffer zones
               Application cycle
                 Time on, h
                 Time off, d
               Avg annual application rate, ft
               Avg annual precipitation, in.
               Avg annual evaporation, in.
               Avg nitrogen loading, Ib/acre
Rapid infiltration
1.1 (summer)
0.4 (winter)
Domestic
Secondary
No
None
5.4
None
Surface (basin flooding)
No
No

8-24
4-5 (summer); 5-10 (winter)
140
34
26
6 700
               1 Mgal/d = 43.8 L/s
               1 acre = 0.405 ha
               1 ft = 0.305 m
               1 in. = 2.54 cm
               1 Ib/acre = 1.12 kg/ha
      7.9.3  Design  Factors
It  is  estimated that the Lake George Village wastewater treatment plant,
with   a  design  capacity  of 1.75  Mgal/d (76.7  L/s), presently serves a
population of approximately 2 100 in the winter  and 12 300  in the summer
[20].   In 1965, the  plant underwent major expansion with  the  addition of
eight  sand beds, and in 1970 one additional bed  was put on  line to bring
the  total   to 21.    The material in the beds ranges from coarse to fine
sand,   with  a  few  beds having some clay content.   Depth to  water table
and  bedrock  varies,  but is generally deeper in the old  north sand beds
                                     7-54

-------
                  FIGURE 7-18

RAPID INFILTRATION BASIN, LAKE GEORGE, NEW YORK
                  FIGURE 7-19

      OPERATIONAL BASIN COVERED WITH ICE,
             LAKE GEORGE, NEW YORK


                      7-55

-------
                FIGURE 7-20

LAKE GEORGE  VILLAGE WASTEWATER  TREATMENT
      PLANT  AND SAMPLING LOCATIONS
     GENERAL
   6ROUNOWATER
    MOVEMENT
                             PREAPPLICAT
                               TREATMENT
                               FACIL
                   7-56

-------
than  in  the  new south sand beds.  Well points driven in bed 11  of the
north  sand  beds  have  found  the  water  table  to  be  at a depth of
approximately  65 ft  (20 m)  below  the  surface,  and  bedrock  to  be
approximately  90 ft  (27 m)  below  the surface.  The sand beds vary in
size, ranging from 0.16 acre to 0.42 acre (0.06 to 0.17 ha), and combine
for a total surface area of 5.4 acres (2.2 ha) [21].
The  unchlorinated  secondary  effluent  is  discharged onto the natural
delta sand beds by surface flooding.  In order to prevent erosion of the
sand  at the point of discharge, concrete splash pads with brick baffles
are  provided.   Individual  sand  beds are dosed by adjusting the gates
within  the distribution chambers.  The beds have 3 to 5 ft (1 to 1.5 m)
dikes  around  them,  and  each  bed  has a control valve for individual
flooding.   The 14 lower (north) beds are fed by gravity, while effluent
from  the  secondary  settling  tank  must  be  pumped up to the 7 upper
(south)  beds.   A  float control in the wet well automatically operates
the intermittent pump.


Vertical  movement  of  the infiltrated effluent through the sand ranges
from  15 to  75 ft  (4.5 to  20 m),  depending  on  the sand bed and the
season.   Horizontal  underground  movement  is  approximately  2 000 ft
(600 m)  before  the  renovated  effluent  emerges as seepage near  West
Brook, a tributary to Lake George.


     7.9.4  Operating Characteristics and Performance
Normal  weekday  operation of the sand beds is to dose one north and one
south  bed with 8 to 10 in. (20.4 to 25.4 cm) of effluent over an 8 hour
period  during  the  day.  A similar pair of beds are flooded throughout
the  remaining  16 hours.  On weekends, two north and two south beds are
dosed for a period of 24 hours each.  During the high flow months of the
summer, more than 2 beds are flooded at a time.
There is no set schedule as to which rapid infiltration bed will  be used
on  any  one  day.  Plant personnel make daily decisions based on visual
inspection of the status of the beds.  Most of the sand beds dry  in 1  to
3 days.   Generally,  the  beds are rested for 5 to 10 days prior to the
next  application.   The  frequency  of  application  increases with the
increase in flow due to the influx of tourists during the summer  months.
During the peak flows of August, it is often necessary to flood the sand
beds  before  they have fully dried.  This practice is avoided if at all
possible,  as  the  surface  of the beds must remain aerobic in order to
restore the renovative capacity of the system.
It  has  been  found that the rapid infiltration basins perform well  and
clog slowly under conditions of 1  day dosing followed by several days of
drying.   The  rest  period, providing complete or partial  drying, has a
renewing  effect  on  the  infiltration  capacity  of the sand beds.   In
                                   7-57

-------
addition,  the  sand  beds  are  occasionally reconditioned by raking  or
scraping  the  surface.   The  top  few centimetres of sand are removed,
which  include  a  mat of algae and other organic material, and the sand
bed  is  regraded.   This  cleaning operation is generally restricted  to
spring  or  autumn,  when  weather  is mild and flows are not at a peak.
Weeds  are  removed  for aesthetic purposes.   There have been no serious
problems with the operation of the sand beds.
Application  continues  year-round without storage,  regardless of severe
winter  weather.   In winter, part of the water freezes and forms an ice
layer  which  may  attain  1 ft  (0.3 m)   in   thickness.    This does not
interfere  with  the  operation.   The warm effluent  flows under the  ice,
simultaneously  melting the ice above it and  the ground below it, and in
effect,  floats  the  ice  layer.  The ice is actually beneficial to the
process, as it serves as an insulating layer  for the soil  surface.
     7.9.5  Environmental Studies
In  an  effort  to evaluate the environmental  effects of the Lake  George
Village wastewater treatment plant, numerous  studies have been conducted
by   Rensselaer   Polytechnic  Institute,   the  New  York  State  Health
Department,   and   the  New  York  State   Department  of  Environmental
Conservation.   The  Rensselaer  Fresh Water  Institute was organized and
studies  were begun in 1968.  A number of  well  points were placed  in the
sand  beds and at the periphery of the treatment plant grounds,  as shown
in  Figure 7-20.  Two additional  well  sites are located between  the sand
beds and West Brook and one is located across  West Brook.
Analysis  of water samples from the wells has  shown that there is  almost
complete  removal  of  BOD,  coliforms,   ammonia  nitrogen,   and organic
nitrogen  in  the top 10 ft (3 m)  of passage  through the sand beds [22].
Ammonia  and  organic nitrogen are converted  to nitrate-nitrogen and,  at
least partly, the nitrate is reduced to  nitrogen gas by denitrification.
Phosphorus  removal  is a function  of the frequency of sand bed use,  with
a bed in constant use having considerably less phosphate removal than  an
infrequently used bed for the same distance of downward percolation.


A  resistivity  survey has indicated that the  most probable  direction  of
flow  of the wastewater discharged onto  the sand beds is northerly along
Gage  Road  toward  West Brook [23].  The seepage which occurs above and
below  Gage Road is tributary to West Brook and has been estimated to  be
approximately  0.6  Mgal/d  (26 L/s),  or  10%  of   the  total  flow  of
West Brook [24].
Water quality data of the plant effluent and  seepage above Gage  Road  and
West  Brook  are given in  Table 7-28.   The water which emerges  from  the
ground   in   the  area  of  West  Brook  contains  considerably  higher
concentrations  of  dissolved  solids,  alkalinity, and chloride  than  the
                                   7-58

-------
                                                           TABLE 7-28

                                              WATER QUALITY DATA, SEASONAL MEANS,
                                                  LAKE GEORGE, NEW YORK [25]
--J

01

Plant effluent
applied to
sand beds
Spring
Summer
Fall
Winter
Seepage above
Gage Road
Spring
Summer
Fall
Winter
West Brook
downstream
of seepage
Spring
Summer
Fall
Winter
Temper-
ature,
°C


13.0
22.4
10.0
4.5


10.8
14.3
8.9
4.8



10.7
12.6
8.0
2.0
Dissolved
oxygen ,
mg/L


5.3
2.1
4.5
6.8


10.3
8.2
10.1
11.3



11.0
10.2
11.5
13.0
Dissolve
solids ,
mg/L


177
224
197
234


160
173
220
212



85
120
93
79
d /
pH


7.2
6.9
7.0
7.0


7.9
7.8
7.9
7.8



7.4
7.8
7.5
7.3
Ukal inity,
mg/L as
CaCOa


96
218
93
109


106
99
111
118



35
€8
56
39
Chloride,
mg/L


44
46
32
52


37
49
42
40



15
29
25
14
Nitrate-
nitrogen ,
mg/L


1.8
1.6
3.5
1.1


2.3
1.6
3.5
3.8



0.7
1.8
1.5
0.6
Ammonia
nitrogen ,
mg/L


3.8
15.9
3.0
5.1


0.0
0.0
0.1
0.0



0.0
0.1
0.0
0.0
Total
Kjeldahl
nitrogen ,
mg/L


8.0
18.4
9.1
12.5


0.2
0.1

o!i



0.2
0.1
0.0
0.1
Soluble
phosphate,
ug/L


750
2 950
700
488


8
14
<2
10



1
3
1
2
Total
phosphorus,
pg/L


1 555
3 950
1 650
1 425


16
16

10



6
3
2
6

-------
natural groundwater in the area.   This is  evidence that the seepage  does
in  fact  originate  from wastewater effluent.   From the data,  it can  be
seen  that  the  total  phosphorus  content of  the applied wastewater  is
reduced  by  greater than 99% in  its passage through  the  approximately
2 000 ft  (600 m) of sand before  it emerges and runs off into West Brook
and  ultimately  into Lake George.  It also can be seen that the applied
nitrogen  is oxidized to nitrate  prior to  its emergence from the ground.
The  nitrate  content  of  the  seepage is  about  1.6  to 3.8 mg/L and
increases  the  nitrate  content   of West  Brook.   However, the   nitrate-
nitrogen concentration  in West Brook downstream of the seepage is about
0.6  to 1.8 mg/L, which is well  below the  EPA drinking water standard  of
10 mg/L.
Based  on numerous studies and extensive  sampling and analyses,  the  land
treatment  system  at  Lake George is doing  an  adequate job  of purifying
the  wastewater  to  a  drinking water quality  [22].   The  soil  system  is
satisfactorily  removing  essentially  all   of   the  phosphorus   and  is
providing  a  nitrified  effluent  which   appears to  have  no deleterious
effect upon the quality of Lake George.
7.10  Fort Devens, Massachusetts


     7.10.1  History
Fort  Devens  is a U.S. Army military installation located  in  the  Nashua
River  basin  about 32 mi (52 km)  northwest of  Boston,  Massachusetts.   A
rapid  infiltration  system at Fort Devens  has  received an  unchlorinated
primary  sewage  effluent  for  over 35 years.   The total population  and
wastewater  flows  have  fluctuated over  the years, but are presently  on
the  decline.  In 1973, the daytime population  was about 15 000 of which
10 400  were  permanent  residents [26];  whereas the 1976 population  has
been  estimated  to  be  10 000  and  7 000, respectively. The present
wastewater  treatment  facility   has been providing continuous service
since  its  construction in 1942.   Selected design factors  are presented
in Table 7-29.
     7.10.2  Project Description and Design  Factors


The  Fort  Devens wastewater treatment facility  has  a design  capacity  of
3.0 Mgal/d  (131 L/s), but has been receiving  from 1.0 to 1.3 Mgal/d (43
to 57 L/s) for the last several  years.  Comminuted,  degreased wastewater
is  pumped  from  a  central  pumping station to  three Imhoff  tanks which
provide  primary  treatment.   Settlcable solids  accumulate on the bottom
of the Imhoff tanks and are withdrawn to sludge  drying beds in April  and
in  November  of  each year.   These dewatering beds  are underdrained and
discharge to an adjacent wetland area [27].
                                   7-60

-------
                                 TABLE  7-29
                               DESIGN FACTORS,
                         FORT DEVENS, MASSACHUSETTS
                Type of system
                Avg flow, Mgal/d
                Type of wastewater
                Preapplication treatment
                Disinfection
                Storage
                Field area, acres
                Crops
                Application technique
                Routine monitoring
                Buffer zones
                Application cycle, d
                  Time on
                  Time off
                Avg annual application rate,
                1960 to 1973,  ft
                Avg annual precipitation, in.
                Avg annual evaporation, in.
                Annual nitrogen loading, Ib/acre
Rapid infiltration
1.3
Domestic
Primary (Imhoff tank)
No
Not required
16.6
None (weeds)
Surface (basin flooding)
No
No

2
14
94

44
26
11 200
                1 Mgal/d = 43.8 L/s
                1 acre = 0.405 ha
                1 ft = 0.305 m
                1 in. = 2.54 cm
                1 Ib/acre = 1.12 kg/ha
Final   treatment  of   the  unchlorinated primary effluent is achieved by
discharging  to 22  rapid infiltration basins.  These 22 basins  provide a
total field area of 16.6 acres (6.7  ha)  or an average of 0.76 acre (0.31
ha) per basin [28].   They are situated on the top  of a  steep-sided hill
composed  of  a  200  ft  (60 m) thick layer of unconsolidated stratified
sand  and gravel deposited by receding glaciers.  This flat,  oval-shaped
hilltop  rises  approximately  70  ft  (21 m) above the floodplain  of the
Nashua   River [26].   The soil formation in which the treatment  beds were
constructed  is  primarily  poorly  graded  sands  or gravelly sands with
interspersed  lenses   of  silty  sand  and sandy gravels.  Particle size
distribution  differs  appreciably  between the various soil horizons in
the   beds.    The  layout  of  the  Fort Devens land treatment facility is
schematically depicted in Figure 7-21.

      7.10.3  Operating Characteristics

Effluent  is distributed within each treatment bed by discharging  onto a
tapered  concrete   trough  with slotted wooden splashboards, as shown in
                                     7-61

-------
Figures 7-21  and  7-22.   A  view  of several  grass-covered basins with
accumulated organic material on the surface is  shown in Figure 7-23.


Under normal  operating  conditions,  the  application cycle consists of
flooding  three  treatment  beds  concurrently  with effluent for a 2 day
period,  then allowing a 14 day recovery or  dry-up period.  On a yearly
basis, each bed receives effluent for a total  of 52 days [27].
After  the  2 days of flooding, effluent has normally accumulated on the
surface  of  the  beds  to a depth of 0.5 to 1.6 ft (15 to 50 cm).  This
standing  water  infiltrates  the beds within the initial  2 or 3 days of
the  recovery period, restoring aerobic conditions to the surface of the
beds.  Winter conditions, while reducing infiltration rates somewhat, do
not  interfere  with  normal  operations.   The effluent is sufficiently
warm,  46 to  54°F (8 to 12°C) during the winter to melt any accumulated
ice and snow cover and to infiltrate and move through the sand beds.
Operation of the Fort Devens rapid infiltration basins normally involves
no  routine  maintenance.  Solids build up on the surface, dry and crack
during  the  recovery  period,  and  are  degraded  under the prevailing
aerobic  conditions.  During the summer, the sand beds have a good stand
of  naturally  occurring  annual grasses and weeds (see Figure 7-22  and
7-23).  No attempt is  made  to  remove this vegetation as there  is  no
apparent detrimental effect.  However, renovation of the bed surface has
been  performed. This renovation consists of excavation to a depth of 1 ft
(0.3  m)  depth  to  1.5  to 4.0 ft (0.45 to 1.22 m) in order to remove a
an  area  adjacent  to  the  treatment  beds.   The  exposed  surface is
scarified  or  raked prior to replacement of the excavated material.  It
should  be  pointed  out  that this renovation procedure is not required
very  often.   The only cleaning operation was completed in October 1968
[26].    At  this  time  it was necessary to excavate below the  specific
1  ft  (0.3 m) depth to 1.5 to 4.0 ft (0.45 to 1.22 m) in order to remove a
tarlike  layer  about  1.5 ft  (0.45 m) thick which had formed below the
surface  of  the beds.  Since the discovery of this tarlike layer, there
has   been  more  surveillance of the dumping of oils and grease into the
system.   Grease traps, installed at various locations in the collection
system  to  remove  kitchen  grease  and  fats and various oils from the
wastewater, are cleaned more frequently, and the materials collected are
deposited in sanitary landfills [27].
Normal  operation  and maintenance of the Fort Devens treatment facility
is  carried  out  by two  full-time employees.  The application of daily
flows  to  various  combinations  of  treatment  beds  is  based  on the
continued  capacity  of  the  beds  to  accept  the  effluent  and  from
operational experience developed over the years.
                                   7-62

-------
                                                               FIGURE 7-21
                                         LAND TREATMENT SYSTEM, FORT  DEVENS, MASSACHUSETTS
01
OJ
                                                                           WELL*1
                                  CONCRETE TROUGH
                                  WlTH WOODEN
                                  SPLASHBOARDS
 SAND
FILTER
 BED
                                                          20
                                                           DISTRI-
                                                           BUTION
                                                           GA TE  BOX '
                                                                           OPERATOR'S
                                                                       \    BUILDING
                                                          IMH 0 F F TANK    \
                                                                        \
                                             SLUDGE  DRYING BEDS
                                                                                                        SROUNDWATER
                                                                                                        MONI TOR ING WELLS

-------
                    FIGURE 7-22

DISTRIBUTION CHANNEL INTO RAPID INFILTRATION BASIN,
            FORT DEVENS, MASSACHUSETTS
                    FIGURE 7-23

        GRASS COVERED INFILTRATION BASINS,
            FORT DEVENS, MASSACHUSETTS

                       7-64

-------
     7.10.4  Treatment Performance
During   1973  and  1974,  the  U.S.  Army  Cold  Regions  Research  and
Engineering  Laboratory (CRREL) conducted extensive studies to determine
the  effectiveness  of  the  rapid infiltration basins at Fort Devens to
renovate  unchlorinated  primary  sewage  effluent.  Groundwater quality
beneath  the  application site and the surrounding area was monitored by
collecting  and  analyzing  bi-weekly  samples from 21 observation wells
(Figure 7-21).   Results of the chemical and bacteriological analyses of
the  primary  effluent  and selected observation wells are summarized in
Table 7-30.


Analysis  of  the  data  has  proved  that the rapid infiltration system
serving Fort Devens is treating unchlorinated primary sewage effluent to
a   quality   comparable  to  that  achieved  by  conventional  tertiary
wastewater  treatment  facilities.   The  treatment basins were found to
greatly  reduce the levels of  BODg,  COD, organic and ammonia nitrogen,
phosphorus,  and  total  coliform  bacteria  in  the  applied  effluent.
Although  most  wastewater  constituents  were  increased  in the native
groundwater,  the quality of the groundwater peripheral to the treatment
sites continues to meet EPA drinking water standards, with the exception
of  nitrate-nitrogen and   coliform   bacteria.   While  fecal  coliform
determinations  proved  negative, total coliforms showed a mean value of
200 per 100 mL in the peripheral groundwater wells [26].
     7.10.5  Research Studies
In  1974,  further  studies  by  CRREL  were undertaken in an attempt to
optimize  nitrogen  removal.   The  objectives  were  to  remove greater
amounts of nitrogen by management of the treatment system to enhance the
nitrification-denitrification  processes.  In an effort to achieve this,
the  application  cycle  was modified from inundating 3 beds for 2 days,
followed  by  a 14 day recovery period, to inundating 9 beds for 7 days,
followed  by a 14 day recovery period.  Results of this study have shown
that  an increase in inundation period continued to renovate the primary
effluent to a degree comparable to before.  The total nitrogen levels of
the  groundwater  continued  to be 20 mg/L.  However,'when the treatment
basins  were  inundated  for  7 days,  the  percentage of total nitrogen
removal   was greater than when the basins were inundated for 2 days.  By
increasing   the   inundation  period,  total  nitrogen  additions  were
increased  by  54%  from  about  32 to  50 lb/acre-d (36 to 55 kg/ha-d).
Although  total  nitrogen additions were larger during the 1974 study, a
proportional  increase  in groundwater nitrogen levels was not observed,
indicating  a  greater percentage of nitrogen removal.  However, after 6
months  of  increased  inundation  period, the infiltration capacity had
been  reduced  so  much  that  the  basin surfaces were still wet at the
beginning  of  the  next cycle of inundation and recovery.  This gradual
decline  in  the  basin  infiltration  capacity  over several months was
attributed  to  clogging  of  the surfaces of the basins by accumulating
                                   7-65

-------
organic  matter.    It  was  found  that  an occasional  extended recovery
period  of 60  consecutive days will rejuvenate  the infiltration capacity
of  the  treatment  basins so that the 7 day application/14 day recovery
cycle  can once  again be used.  The restoration of infiltration capacity
during the extended recovery period is attributed to the aeration of the
surface and  the  subsequent oxidation of accumulated organics [29].
                                TABLE 7-30

         CHEMICAL  AND BACTERIOLOGICAL CHARACTERISTICS OF PRIMARY
         EFFLUENT  AND GROUNDWATER IN SELECTED OBSERVATION WELLS,
       FORT  DEVENS LAND TREATMENT SITE (1973, Average Values) [27]
Well3
Constituent6
BOD5
COD
Total nitrogen
Organic nitrogen
Ammonium nitrogen (NH.-N)
Nitrate nitrogen (N03-N)
Nitrite nitrogen (N02-N)
Total phosphate (P04-P)
Ortho phosphate (P04-P)
Chloride
Sulfate
Total col i forms, MPN/100 ml
ph, units
Conductivity, umhos
Alkalinity (as CaCOg)
Hardness (as CaCO,)
Depth of well below
ground level, ft
Primary effluent
112
192
47
23
21
1.3
0.02
11
9
150
42
3.2 x 107
6.2 - 8.0
511
155
41
--
1C
3.5
42
1.3
0.5
0.6
0.2
0.01
0.4
0.1
20
9
335
7.3
133
29
12
40
2
12
26
14.5
8.3
5.3
0.9
0.03
5.9
5.6
85
48
3 900
6.8
371
120
23
64
3
2.5
19
19.5
2.3
1.3
15.6
0.3
0.9
0.2
230
39
210
6.3
360
28
44
9.5
10
0.9
10
20.3
1.2
0.5
18.6
0.02
1.3
0.1
257
35
620
6.1
333
14
30
23
        a.  Well locations are shown in Figure 7-20.

        b.  mg/L unless otherwise noted.

        c.  Indicative of native groundwater quality.

        1 ft = 0.305 m
                                    7-66

-------
A  tracer  study  conducted  by  the  U.S.   Army  Medical  Bioengineering
Research  and  Development  Laboratory has  demonstrated that viruses are
capable of movement past the upper soil  layers [28].  The wastewater was
artificially  spiked  to  provide  a  continuous  virus concentration of
105 PFU/mL  of wastewater applied to the treatment beds.  This is a much
greater  virus  concentration  than  that  normally  found  in  domestic
wastewaters.   The  field studies at Fort Devens have shown that viruses
at  this  concentration are not impeded in  the local soil  strata and can
readily  penetrate  to the groundwater.  In addition to poor adsorption,
other  removal  mechanisms  such  as  filtration or straining were not a
factor,  mainly  because  of  the size of the sandy, silty, and gravelly
soils  in  relation  to  the extremely small virus particles.  The virus
stabilized in the groundwater beneath the treatment basins at almost 50%
of the artificially high applied virus concentration.


The   bacteriological   indicator  organisms  were  reported  to  behave
differently  than  the  viruses  at  the rapid infiltration site.  Total
coliform, fecal coliform, and fecal streptococcus organisms were readily
concentrated on the soil surface.  Unlike the viruses, the bacteria were
filtered or strained at the soil surface.  However, it was reported that
significant  numbers  of  bacteria  are  capable  of  migration into the
groundwater [28].
7.11  Pauls Valley, Oklahoma


     7.11.1  History
Pauls  Valley  is  a  community  of 6 000 in south central Oklahoma.  In
1962,  a  4  cell,  33  acre (13 ha) lagoon was constructed to treat 0.7
Mgal/d  (31 L/s)  of wastewater, with some effluent used for irrigation.
In 1975, an experimental overland flow system was constructed to treat a
portion  of  the  flow.   Much  of the experimental system was patterned
after  the  EPA  research project at nearby Ada, Oklahoma [30, 31].  The
principal design factors are summarized in Table 7-31.


     7.11.2  Project Description and Objectives


The  purpose  of the experimental system is to demonstrate the treatment
of  both oxidation lagoon effluent and untreated municipal wastewater by
overland  flow.  The system consists of 32 terraces, each 0.25 (0.1 ha),
for  a  total  of  8 acres  (3.2 ha).   Lagoon effluent is supplied to 8
terraces  and screened untreated wastewater is supplied to the remaining
24 terraces.  Lagoon effluent is taken from the second cell where it has
received approximately 30 days of detention.


Half the terraces are sloped at 2% and half at 3%.  A typical terrace is
75 ft  wide by 150 ft long (23 m by 45 m).  Three distributor mechanisms
                                   7-67

-------
                                  TABLE 7-31
                                DESIGN FACTORS,
                            PAULS VALLEY,  OKLAHOMA
         Type of system
         Avg flow, Mgal/d
         Type of wastewater
         Preapplication treatment
         Disinfection
         Storage
         Field area, acres
         Crops
         Application technique

         Routine monitoring
         Buffer zones
         Application cycle, h
           Time on
           Time off
         Annual application rate, ft
           Screened untreated wastewater
           Oxidation lagoon effluent
         Avg weekly application rate, in.
           Screened untreated wastewater
           Oxidation lagoon effluent
         Avg annual precipitation, in.
         Avg annual evaporation, in.
         Capital costs, $/acrea
Overland flow
0.2
Domestic
Raw  (screened) and oxidation lagoon
No
Not  required
8
Fescue, annual rye, and Bermuda grass
Surface (bubbling orifice) and
sprinkler (fixed and rotating nozzle)
Yes
No

8-12
12-16

19
45

4'. 3
10.3
36
58.5
8 500
         a.  Includes construction costs  of preapplication treatment and
             engineering, 1975.
         1 Mgal/d = 43.8 L/s
         1 acre = 0.405 ha
         1 ft = 0.305 m
         1 in. = 2.54 cm
         1 Ib/acre =1.12 kg/ha
         1 $/acre =$2.47/ha
are  used:   (1) rotating  booms  with fan nozzles,  (2)  fixed fan  nozzles  at
the   top   of  the   slope  as   shown  in Figure 7-24,  and  (3) the bubbling
orifice  method  as shown in Figure 7-25.  The rotating boom is patterned
after those used at the  Ada, Oklahoma  research project [30].
The   purpose  of   the  multiple  terraces   is  to   compare the treatment
efficiencies  and  the operating conditions  for:   (1)  screened untreated
wastewater   versus  oxidation   lagoon  effluent,  (2) slopes at 2% versus
slopes at 3%, and (3) the three types of distributors.
                                       7-68

-------
                              FIGURE 7-24

                FIXED  FAN  NOZZLE, PAULS VALLEY, OKLAHOMA
     7.11.3  Design Factors
The original  seeding was 30 Ib/acre (34 kg/ha)  fescue  and  15  Ib/acre  (17
kg/ha)  annual   rye.   During  the  summer  the  annual  rye  dies  out  and
subsequent   seeding  with  Bermuda  grass  has  begun  to   grow.    The
application  is  year-round;   however,   the  oxidation
backup system and would provide storage if needed.   The
permeable red clay.
lagoon acts as a
soil  is a slowly
The  bubbling orifice consists of a 6 in.  (15  cm)  PVC  manifold with  0.75
in.  (1.9 cm)  outlets.    The  manifold  is cradled in readily available
crushed  limestone  that  is  0.6  in.   to  1.50  in.  (1.6  to  3.8  cm)  in
diameter.   The  flow  of  wastewater  spreads  out and slows  down as  it
contacts the limestone and begins to travel down the slope.
                                  7-69

-------
                              FIGURE  7-25

             BUBBLING  ORIFICE  FOR  WASTEWATER  APPLICATION,
                        PAULS  VALLEY,  OKLAHOMA
     7.11.4  Operation and Performance
Two  related  operating  problems  have  taken much of the first year to
solve.   The screening device used was not successful  initially and large
solids  were  pumped  into  the  system.   This has resulted in frequent
clogging  of  the sprinkler nozzles.  Improved screening has reduced the
clogging.   Second,   the   grasses  suffered  from  the  heat and   the
occasional   dry  periods  of the first summer.  Bermuda grass may become
the principal  vegetation because of its tolerance for heat and water.
     7.11.5  Costs
The  construction cost for the research system in 1975 was approximately
$68 000,  including  roads,  fencing, seeding, preappl ication treatment,
                                  7-70

-------
earthwork,   distribution,  runoff piping,  and engineering.  Unit costs of
the   three   distributor systems are presented in  Table 7-32.  Each unit
supplies wastewater to a 0.25 acre (0.1  ha) terrace along the top of the
slopes.
                                TABLE  7-32
                 UNIT  COSTS OF  OVERLAND FLOW APPLICATION,
                          PAULS VALLEY, OKLAHOMA
                                             Unit cost,   Cost, $
                     Item          Unit  Number     $      per acre


              Fixed nozzle systems     each    8     200        800

              Rotating boom systems    each   16     375      1,500

              Bubbling orifice systems  each    8     140        560
7.12  Paris, Texas


     7.12.1  History
In  1960,  the Campbell  Soup  Company  began to construct an overland flow
system  at Paris, Texas.   When  the food processing plant began operating
at  the  end  of  1964,  there were 300  acres (120 ha)  of prepared slopes
with a vegetative cover  of mixed grasses ready for wastewater treatment.
The  system  has  been   expanded  in  three increments  to the present 900
acres  (360  ha).    In 1968,  a  12  month intensive monitoring program was
conducted  and  the  results have been widely published [32,  33,  34, 35].
The principal design  factors  are presented in Table 7-33.
     7.12.2  Objectives  and  Description
The  objective  of   the   overland   flow   system  is  to  treat  the food
processing  wastewater   in   an  efficient and cost-effective manner [36].
The  construction  of  the   overland   flow  system  also resulted in the
reclamation of the heavily eroded  rolling terrain.


Wastewater  from the heat processing  of  soups,  beans,  and spaghetti-type
products  is  collected   in  two drainage systems.   The first,  containing
grease from cooking, is  routed  through a gravity  grease separator before
it  joins the second waste stream  from the vegetable trimming  area.  The
combined  stream  passes  through   revolving  drum-type #10-mesh screens
prior to being pumped to  the sprinklers  [34].
                                  7-71

-------
                                   TABLE  7-33
                                DESIGN FACTORS,
                                  PARIS,  TEXAS
            Type of system
            Avg flow, Mgal/d
            Type "of wastewater
            Preapplication treatment
            Disinfection
            Storage
            Field area, acres
            Crops

            Application technique
            Routine monitoring
            Buffer zones
            Application cycle, h
              Time on
              Time off
            Annual application rate, ft
            Avg weekly application rate,  in.
            Avg annual precipitation, in.
            Avg annual evaporation, in.
            Annual nitrogen loading, Ib/acre
            Capital costs, $/acrea
            Unit operation and maintenance
            cost, £/l 000 galb
Overland flow
4.2
Food processing
Grease removal and screens
No
Not required
900
Reed canary, tall fescue, redtop,
and perennial rye
Sprinkler (buried pipe)
Yes
No

6-8
16-18
5.2
2-3
45
36
240
1 500

4.8
             a.  Excluding land, 1976.
             b.  1971.
             1 Mgal/d = 43.8 L/s
             1 acre = 0.405  ha
             1 ft = 0.305 m
             1 in. = 2.54 cm
             1 Ib/acre =1.12 kg/ha
             1 $/acre = $2.47/ha
             1 4/1 000 gal = 0.264
Wastewater  is   applied  to   the   overland   flow  terrace  by   impact-type
sprinklers.    The  original   sprinkler  system consisted of 4  in. (10  cm)
aluminum   irrigation   pipe as laterals  laid  on the  surface
recently   constructed   terraces   have   buried   laterals.
wastewater is collected as runoff in grassed waterways and is discharged
into a creek.
                          but  the more
                          The   treated
                                       7-72

-------
     7.12.3  Design Features
While  the current hydraulic loading is 5.2 ft/yr  (1.6  m/yr),  the  system
has operated effectively at higher rates.  In  the  1968  research  program,
the  total annual application was measured at  11 ft  (3.4 m)  for  the  11.4
acres (4.6 ha) monitored and rainfall was 4.7  ft (1.4 m).  Of  this total
amount  of  water,  18%  was accounted for as  evapotranspiration,  61%  as
runoff, and 21% assumed as percolation [34].


The  rolling terrain was graded  into terraces  with slopes  ranging  from 1
to  12%.   In the more recently  added fields,  slopes of from 2 to  6% are
used.   Slope lengths range from 200 to 300 ft (61 to 92 m).   The  slopes
are  seeded to a mixture of Reed canary grass,  tall  fescue,  red  top, and
perennial  rye grass [36].  Reed canary grass  has  become the predominant
grass on the mature slopes.
     7.12.4  Operation and Performance
The  treatment  performance   documented   in   1968   is compared to recent
effluent quality  in Table 7-34.   BOD  and  COD  removals on a concentration
basis  have  improved  and are relatively  consistent throughout the year,
as  shown  in  Table   7-35.  The   suspended   solids  removals are not as
high  as BOD removals  and are not as  consistent.   Despite the wide range
in pH of the wastewater, the  runoff is consistently between 6.6 and 7.5.
                                TABLE  7-34

                    TREATMENT  PERFORMANCE  DURING 1968
       COMPARED TO EFFLUENT QUALITY  IN  1976,  PARIS,  TEXAS [35,  37]
                                     1968 values
                June
                1976
Constituent
BOD, mg/L
COD, mg/L
Suspended sol Ids, mg/L
Total nitrogen, mg/L
Total phosphorus, mg/L
Chloride, mg/L
Influent
572
806
245
17.2
7.4
44
effluent
9
67
16
2.8
4.3
47
effluent
1.9
45
34
• * * •
• • * •
43
                Electrical
                conductivity, j/mhos/cm  449
                pH, unit
4.4-9.3
 490

6.2-8.1
6.6
                                  7-73

-------
                               TABLE 7-35

                  SEASONAL QUALITY OF TREATED EFFLUENT
                              PARIS, TEXAS
                                 mg/L
Month
1975
Jul
Aug
Sep
Oct
Nov
Dec
1976
Jan
Feb
Mar
Apr
May
Jim
Average
BOO

3.1
3.4
1.9
2.7
2.7
3.1

6.5
3.6
3.4
4.6
2.3
1.9
3.3
COD Suspended solids

44
43
38
32
36
34

38
40
44
50
43
45
41

34
17
15
15
23
15

15
19
37
76
38
34
28
The  grass  was  cut but not removed in 1965 and 1966.   In 1967,  the hay
was  harvested and in 1968 three cuttings were made for a total yield of
3.65  tons/acre  (8.2 Mg/ha)  [32].    Currently, the grass is cut once a
year  and  it is harvested green, dried in a hay dryer, and converted to
pellets  for animal feed [36],   The  grassed terraces are shown in Figure
7-26.  Because the slopes are nearly always wet, access is restricted to
vehicles with high-flotation tires.
     7.12.5  Costs
Construction  and  operating  costs  reported in 1971  are shown in Table
7-36. It is estimated that the $1 007/acre ($2 483/ha) construction cost
{excluding  land) has increased to about $1  500/acre ($3  700/ha)  by 1976
[36].
In  1976, 10 men (3/shift) and a supervisor were required to operate the
system.   Maintenance  includes  checking  and replacing sprinkler heads
(which have a service life of 4 to 5 years).
                                  7-74

-------
                  FIGURE  7-26
OVERLAND  FLOW  TERRACES AT PARIS,  TEXAS
                 TABLE  7-36
    CONSTRUCTION AND  OPERATING  COSTS,
          PARIS,  TEXAS [34],  1971
       Construction costs, $/acre
         Site clearing, grading,
         and drainage ditches           362
         Planting  and fertilizing        108
         Pipeline  and
         sprinkler system               348
         Engineering, surveying,
         and equipment                 188
          Total                     1  007
       Operating costs, c/1 000 gal
Labor
Maintenance
Power
Miscel laneous
Subtotal
Revenue
Total
3.2
1.4
0.2
0.4
5.2
0.4
4.8
       1  S/acre =  S2.47/ha
       1  */l 000 qal = 0.264
                 7-75

-------
     7.12.6  Monitoring


In  addition  to  the  constituents  listed   in   Table  7-35,  the  regular
monitoring  program includes analyses of  temperature, pH,  total residue,
chlorides,  sulfates,  oil  and grease, color,  and dissolved oxygen.  The
total  runoff flow is monitored continuously  and  samples  are  taken every
3 days for analyses.
     7.12.7  Microbiology
Research  on  the  soil   microbiology at Paris  has been  reported  by Vela
[38]  and  Vela  and  Eubanks [391.     Populations of  heterotrophic soil
bacteria  ranged from  106  to 1Q8  organisms/gram  of soil  [39].  Large
populations  (1.5  X  105  to 7.4  x  105   organisms/gram   of  soil)  of
psychrophilic  bacteria that are capable of actively growing at 2°C were
also  found,  although  the soil  reaches this low temperature only a  few
days  of the year [38].   This large  microbial population sustains a high
level of treatment even when low temperatures occur.
7.13  Other Case Studies
Many  existing  case studies of land treatment were  necessarily  excluded
in  this  chapter.   Lubbock, Texas, is an example of  a  slow  rate  system
where  a  farmer is contracting for municipal  effluent for  irrigation  on
his  land  [40,  41].   At  Tallahassee,   Florida,  research  on  nutrient
removal  has preceded full scale plans  for treatment [42].  Case studies
of  operations  at Quincy,Washington;  and Manteca,  California [43]; and
Livermore, California [44],  have also been reported.


For  rapid  infiltration the studies at Santee [45]  and  Whitter  Narrows,
California,   [46]   are ° available.    The   Calumet,   Michigan,   rapid
infiltration  system,  probably  the oldest rapid infiltration system  in
the   United   States,   is  being   studied.   Untreated,   undisinfected
wastewater at a flow of 1.2  Mgal/d (53  L/s) has  been treated  on  12  acres
(4.8 ha) since 1887 [47, 48].
The  most  prominent overland flow system that is not included  as  a  case
study  is  at  Melbourne, Australia.   It has been operating  successfully
for several decades [49].
                                  7-76

-------
7.14  References

 1.  Hartman,  W.J.,  Jr.    An Evaluation of Land Treatment of Municipal
     Wastewater  and  Physical   Siting   of  Facility  Installations.  May
     1975.

 2.  Monaco,   A.N.    Personal    Communication.     Public   Works  Field
     Superintendent, City  of Pleasanton, Calif.   October 1976.

 3.  Sullivan, R.H., et al.   Survey of  Facilities Using  Land Application
     of  Wastewater.   Environmental  Protection  Agency, Office  of Water
     Program Operations.  EPA-430/9-73-006.   July 1973.

 4.  Erler,  T.   Personal    Communication.    Kennedy   Engineers.   San
     Francisco, Calif.  October 1976.

 5.  Sorenson,  S.   Personal   Communication.  USGS.   Menlo Park, Calif.
     November 1976.

 6.  Anderson,  E.W.   Twentieth  Annual  Report  of  the  Sewage Treatment
     Works  for Walla Walla,  Washington;  1973.  Walla Walla, Washington.
     December 1974.  27 p.

 7.  Crites,   R.W.    Irrigation   With   Wastewater   at   Bakersfield,
     California.   In:  Wastewater  Use  in  the Production of  Food and
     Fiber, EPA-660/2-74-041.   June 1974.  pp 229-239.

 8.  Texas   Water  Quality  Board.   Intensive Surface  Water Monitoring
     Survey  for  Segment   No.  1421  (Concho River).   Report No. 1MS-2.
     1974.

 9.  Koederitz,  T.L.   Personal  Communication.   Water Superintendent,
     City of San Angelo, Tex.   January  1977.

10.  Weaver, R.W.  Personal  Communication.  Texas A&M.  April 1977.

11.  Culp,   G.L.  and  D.H.   Hinrichs.    A  Review  of the  Operation and
     Maintenance  of  the   Muskegon County Wastewater Management System.
     Muskegon County Board of Works.  Muskegon, Mich. June 1976.

12.  Demirjian,  Y.A.  Land Treatment of Municipal Wastewater Effluents,
     Muskegon   County  Wastewater   System.   Environmental Protection
     Agency, Technology Transfer.  1975.

13.  Walker,  J.M.   Wastewater:   Is  Muskegon   County's  Solution Your
     Solution?   Environmental   Protection  Agency,   Region V, Office  of
     Research and Development.  September 1976.

14.  Corn,  P.   Personal  Communication.   Interstate Development   Corpora-
     tion.   1976.

15.  Lehtola,  C.  and J.  Ayars.  Personal Communication.  Department  of
     Agricultural Engineering, University of Maryland.  1976.
                                   7-77

-------
16.  Bouwer,  H.,   R.C.   Rice,   and   E.D.    Escarcega.    High-Rate   Land
     Treatment  I:    Infiltration and  Hydraulic  Aspects  of  the  Flushing
     Meadows Project.  Jour.  WPCF.   46:834-843,  May  1974.

17.  Bouwer,  H.,   J.C.  Lance,  and M.S.  Riggs.  High-Rate Land Treatment
     II:   Water  Quality  and   Economic Aspects  of the Flushing Meadows
     Project.  Jour.  WPCF.  46:844-859, May 1974.

18.  Bouwer,   H.     Personal    Communication.     Director,   U.S.  Water
     Conservation  Laboratory,  USDA,  Phoenix, Ariz.  March 1977.

19.  Gilbert,  R.G.,  et  al.    Wastewater   Renovation and Reuse:  Virus
     Removal  by  Soil  Filtration.  Science.  (Reprint).  192:1004-1005,
     June 1976.

20.  Aulenbach,   D.B.   and  T.J.   Tofflemire.    Thirty-Five Years of
     Continuous  Discharge of Secondary Treated Effluent  Onto Sand Beds.
     Ground Water.   13(2):161-166, March-April 1975.

21.  Beyer,  S.M.    Flow Dynamics in the Infiltration-Percolation Method
     of Land Treatment.   M.S.   Thesis,  Rensselaer Polytechnic Institute,
     Troy, N.Y. May 1976.

22.  Aulenbach,  D.B.,   N.L. Clesceri,  T.J.  Tofflemire, S. Beyer, and L.
     Hajas.  Water Renovation Using  Deep Natural  Sand Beds.   Jour. AWWA.
     67:510-515, September 1975.

23.  Fink, W.B., Jr. and D.B.  Aulenbach. Protracted  Recharge of Treated
     Sewage Into Sand,  Part II  -  Tracing the Flow of  Contaminated Ground
     Water  With  a  Resistivity   Survey.   Ground Water.  12(4):219-223,
     July-August 1974.

24.  Aulenbach, D.B., et al.  Protracted Recharge of  Treated Sewage  Into
     Sand.    Part   III -   Nutrient   Transport  Through   the  Sand.
     Groundwater.   12(5):301-309, September-October 1974.

25.  Hajas,  L.   Purification   of Land Applied Sewage Within the Ground
     Water.   Thesis,  Rensselaer Polytechnic   Institute,   Troy,    N.Y.
     December 1975.

26.  Satterwhite,  M.B.  and G.L.  Stewart. Evaluation  of an Infiltration-
     Percolation System  for  Final  Treatment of  Primary  Sewage  Effluent
     in  a  New  England  Environment.   In:  Land as a Waste Management
     Alternative.    Loehr,  R.C.   (ed.).   Ann Arbor, Ann Arbor  Science.
     1977.  pp 435-450.

27.  Satterwhite,   M.B.,  et  al.   Rapid Infiltration of Primary Sewage
     Effluent  at   Fort  Devens,   Massachusetts.   U.S. Army  Cold Regions
     Research and  Engineering Laboratory.   Hanover, N.H.  1976.

28.  Schaub,  S.A., et al.  Land  Application of Wastewater:   The Fate of
     Viruses,  Bacteria,  and Heavy  Metals  at a Rapid Infiltration Site.
     U.S.   Army   Medical   Bioengineering   Research  and   Development
     Laboratory.  Fort Detrick,  Md.   May 1975.
                                 7-78

-------
29.  Satterwhite,  M.B., et al.   Treatment of Primary Sewage  Effluent by
     Rapid   Infiltration.    U.S.     Army  Cold  Regions   Research  and
     Engineering Laboratory.  Hanover, N.H.   1976.

30.  Thomas,  R.E.,  K. Jackson, and L.  Penrod.   Feasibility  of  Overland
     Flow  for  Treatment  of  Raw  Domestic  Wastewater.   Environmental
     Protection  Agency, Office of Research and  Development.   EPA-660/2-
     74-087.  July 1974.

31.  Thomas,  R.E., B. Bledsoe,  and K. Jackson.   Overland  Flow Treatment
     of  Raw  Wastewater With Enhanced Phosphorus Removal.  Environmental
     Protection  Agency, Office of Research and  Development.   EPA-600/2-
     76-131.  June 1976.

32.  C.W.  Thornthwaite  Associates.   An  Evaluation  of   Cannery Waste
     Disposal   of  Overland  Flow  Spray  Irrigation.   Publications  in
     Climatology, 22, No. 2.  September 1969.

33.  Thomas,  R.E.,  J.P.  Law,   Jr., and C.C.  Harlin, Jr.  Hydrology of
     Spray-Runoff  Wastewater  Treatment.  Journal  of the  Irrigation and
     Drainage   Division,  Proceedings  of  the    ASCE.    96(3):289-298,
     September 1970.

34.  Gilde,  L.C.,  et  al.   A Spray Irrigation System for Treatment of
     Cannery Wastes.  Jour. WPCF.  43:2011-2015, October 1971.

35.  Law,  J.P.,  Jr.,  R.E. Thomas, and L.H. Myers.   Cannery Wastewater
     Treatment  by  High-Rate  Spray on Grassland.   Jour.  WPCF,  42:1621-
     1631, 1970.

36.  Neeley,  C.H.   The Overland Flow Method of Disposing of Wastewater
     at  Campbell Soup Company's Paris,  Texas,  Plant.  (Presented at the
     Mid-Atlantic  Industrial Waste Conference.   University of Delaware.
     January 1976.)

37.  Neeley,  C.H.   Personal  Communication.   Plant  Service  Manager,
     Campbell  Soup Co., Paris,  Tex.  1976.

38.  Vela,  G.R.   Effect  of  Temperature  on  Cannery Waste Oxidation.
     Jour. WPCF.  46:198-202, January 1974.

39.  Vela,  G.R.  and  E.R.  Eubanks.   Soil Microorganism Metabolism in
     Spray Irrigation.  Jour. WPCF.  45:1789-1794,  August  1973.

40.  Gray,  J.F.   Practical  Irrigation  With  Sewage  Effluent.    In:
     Proceedings  of  the  Symposium  on  Municipal   Sewage Effluent for
     Irrigation.  Louisiana Polytechnic Institution.   July 1968.  pp 49-
     59.

41.  Wells,  D.M.,  et  al.   Effluent Reuse in  Lubbock.  In: Land as  a
     Waste  Management  Alternative.  Loehr, R.C. (ed.).  Ann Arbor, Ann
     Arbor Science.  1977.  pp 451-466.
                                    7-79

-------
42.  Overman,  A.R  and  A.  Ngu.   Growth  Response  and  Nutrient  Uptake  by
     Forage  Crops  Under Effluent Irrigation.  Commun.  Soil  Science and
     Plant Analysis.  6:81-93,  1975.

43.  Murrman,  R.P.   and  I.K.   Iskandar.   Land Treatment  of  Wastewater.
     (Presented   at   the   8th   Annual   Waste  Management   Conference,
     Rochester,  N.Y.   April  1976.)   Corps of Engineers,  U.S.  Army Cold
     Regions Research and Engineering  Laboratory.   Hanover, N.H.

44.  Uiga,  A.,  I.K.  Iskandar,   and   H.L.  McKim.  Wastewater Reuse  at
     Livermore,  California.  (Presented  at the 8th  Annual Cornell Waste
     Management  Conference,  Rochester,   N.Y.   April   1976.)   Corps  of
     Engineers,   U.S.    Army  Cold Regions  Research  and   Engineering
     Laboratory.   Hanover, N.H.

45.  Merrell,  J.C.,  et  al.   The Santee Recreation  Project,  Santee,
     California,   Final   Report.    FWPCA,   U.S.  Dept.   of the  Interior,
     Cincinnati.   1967.

46.  McMichael, F.D. and J.E.  McKee.   Wastewater Reclamation  at Whittier
     Narrows.  California State Water  Quality Control  Board.    Publica-
   .  No.  33.   1966.

47.  Baillod,  C.R.,  et  al.   Preliminary Evaluation of  88  Years Rapid
     Infiltration  of  Raw  Municipal   Sewage at Calumet,  Michigan.  In:
     Land  as  a   Waste Management Alternative.  Loehr,  R.C.  (ed.).  Ann
     Arbor, Ann Arbor Science.  1977.   pp  435-450.

48.  Uiga,  A.  and R.  Sletten.   An Overview of Land Treatment  From Case
     Studies  of   Existing Systems. (Presented at the 49th Annual Water
     Pollution   Control   Federation   Conference,   Minneapolis,   Minn.
     October 1976.)   Corps of Engineers,  U.S. Army  Cold  Regions Research
     and Enginering Laboratory.   Hanover,  N.H.

49.  Seabrook,  B.L.   Land  Application   of  Wastewater  in  Australia.
     Environmental   Protection Agency,   Office of Water Programs.  EPA-
     430/9-75-017.   May 1975.
                                   7-80

-------
                                Chapter 8

                             DESIGN EXAMPLE
8.1  Introduction
The design of a land treatment system is highly dependent on conditions,
such  as  climate, soil, topography, and many others.  As a cofisequence,
no  design  example  can  be  universal;  however, the example should be
illustrative  of  a  design procedure in which the feasible alternatives
are  developed  and  assessed  according  to  the methods in this design
manual.
This  presentation  is  adapted  from  a  design example prepared by Mr.
Sherwood  Reed  of  USA  CRREL  for  use  in Corps of Engineers training
courses.   It  is  intended to present the development and evaluation of
land  treatment alternatives.  As such, the design is not intended to be
complete,  since  many  components  of  a  complete  system,  such  as a
transmission  system and pumping stations, are omitted.  The elimination
of  these  components  from this example will not allow a complete cost-
effective  comparison  between land treatment and conventional treatment
alternatives.  Cost data used in this example were  taken  from  sources
described in Chapter 3.
The  approach here is to present a statement of the problem and the data
from  which  preliminary  design alternatives, based on annual  loadings,
and  process  performance  estimates  are  developed.   A  relative cost
comparison  between the developed process alternatives is presented from
which  the  most  cost-effective  alternative   can  be chosen  for final
design.   The  final   process design is based on more detailed  analyses,
including monthly loading distributions.
b.2  Statement of Problem
The  problem is to provide adequate wastewater treatment tor a community
that   has  an  existing  primary  treatment  plant  and  surface  water
discharge.   The  recommended  design  must  be  the most cost-effective
alternative and adapted to local  conditions.
8.3  Design Data
     8.3.1  Location
The  problem  area
existing  community
is  located  in the northeastern United States.   The
 has  a present population of 70 000,  with a 20 year
                                  8-1

-------
design  population  of  90 000.  The design wastewater flow is 10 Mgal/d
(438  L/s).  The existing treatment facilities for the community consist
of a primary treatment plant with disinfection and sludge digestion.   At
present,  the effluent is discharged to a river,  and the digested sludge
is  applied  to the land.  The system was constructed in the early 1940s
and  is  in very poor structural  and mechanical  condition, so it will  be
abandoned.
     8.3.2  Climate
The  climatic  influences  on  land treatment are an important aspect in
determining  storage  and length of the application season for slow rate
and  overland flow systems.  The climatic data for the site was obtained
from  the  National  Oceanic  and  Atmospheric Administration's Climatic
Summary  of  the United States for 20 years of record, and are presented
Tn   Table 8-1.    For  the  worst year in 10, there are 142 days (mostly
between  November  and  March) in which the mean air temperature is less
than 32°F (0°C).  As indicated in Section 5.3, this necessitates storage
for  slow  rate  and overland flow systems.  The annual precipitation of
50.2  in.  (128 cm) occurs fairly uniformly throughout each month of the
year.   A  total evapotranspiration of 25.1 in. (64 cm) occurs from late
March  to  early  November.   The  difference  between precipitation and
evapotranspiration,  as  given  in   Table 8-1,
monthly nitrogen and hydraulic balances.
is  used  in  computing
                                TABLE 8-1

                 CLIMATIC  DATA FOR  THE WORST YEAR  IN  10
Temperature, °F
Month
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Annual
Mean
41.6
29.4
26.0
28.4
34.3
47.3
57.5
66.3
72.0
69.8
62.2
51.8
48.9
Mean daily
minimum
31.0
20.8
16.7
16.0
25.0
35.7
46.2
55.3
60.7
58.3
51.4
40.4
38.1
Days with
mean
temperature
±32°F
16
28
30
26
26
7
1
0
0
0
1
7
142
Precipitation (Pr)
Total,
in.
4.8
4.2
4.3
3.5
5.0
4.6
3.9
3.3
3.8
4.0
4.2
4.6
50.2
Days with
mean £0.5 in.
4
3
3
2
4
3
3
2
2
3
2
3
34
(ET)
Evapo-
transpi ration,
in.
0.8
0
0
0
0.2
1.4
3.2
4.6
5.4
4.3
3.3
1.9
25.1
Monthly net
water excess
(Pr - ET), .
in.
4.0
4.2
4.3
3.5
4.8
3.2
0.7
-1.3
-1.6
-0.3
0.9
2.7
25.1
   1 °F =  1.8 x °C + 32
   1 in. = 2.54 cm
                                  8-2

-------
     8.3.3   Wastewater Characteristics
The  characteristics  of  the   wastewater  are   important in determining
hydraulic  and wastewater component application  rates.   To avoid nuisance
conditions  during  winter  storage, biological  treatment in lagoons will
be  provided.  The characteristics of the mostly domestic wastewater are
presented   in   Table 8-2   along  with  the  anticipated  quality of the
wastewater  applied  to  the land after storage.   Limited information on
the  quality  of  the  Susanna   River  and  native  groundwater  is also
presented.   The  concentrations  of  trace  metals   are  low,  and mass
application criteria for them are presented in  Section 8.7.1.3.
                                  TABLE 8-2

                      WATER  QUALITY CHARACTERISTICS3
Parameter
BODs, mg/L
Suspended solids, mg/L
Total dissolved solids, mg/L
Total nitrogen as N, mg/L
Ammonia as N, mg/L
Organic as N, mg/L
Nitrate as N, mg/L
Total phosphorus as P, mg/L
Chloride, mg/L
Dissolved oxygen, mg/L
CCE
Total coliforms, MPN/100 mL

Raw
wastewaterb
240
240
500
40
20
20
0
10
40




Wastewater to
be applied to
landc
40
45
470
28
10
4
14
8
37


2 000

Susanna
Riverd
3.9

250
6.0




20
5.0
0.16


Groundwater6
...

400
. . .


6

35




         a.  Trace metal concentrations are within the typical range for municipal
            wastewaters.  Discussion is included in Section 8.7.1.3.

         b.  Data obtained from existing wastewater treatment plant records.

         c.  Assumed preapplication treatment by aerated lagoon plus storage.

         d.  Data obtained from State Water Quality Control Board.

         e.  Data obtained from USGS.
     b.3.4   Discharge Limitations
The  Susanna  River, which  is  used as a public drinking water supply,  has
an  average   flow  of  60  ft3/s  (1.7 m3/s), a low  flow of 44 ft3/s   (1.2
m3/s), and a  minimum  dissolved   oxygen concentration of 5.0 mg/L.   Five
miles  (8 km)  downstream  from the existing wastewater treatment  plant,
the  Susanna   River  flows   into  an  estuary  which  is widely used  for
                                     8-3

-------
recreation.   The  State Water Quality Regulatory  Agency has imposed the
following  limits  on  surface  discharges   (expressed   as  mg/L,  30 day
averages):


                       BOD5                        4.0
                       Suspended solids               1
                       Phosphorus as P               0.1
                       Total Kjeldahl nitrogen          1
                       Nitrate-nitrogen               5
                       Total nitrogen as N            6
                       Maximum total chlorine residual    0.1
                       Total coliforms, organisms/100 nl  3
The  groundwater  aquifer  is a potential drinking  water  source and fits
Case  I  (see  Section  5.1.1)  so  the  EPA drinking  water  criteria for
chemical  and  pesticide  levels  would therefore apply to discharges to
groundwater. The most critical groundwater criterion would be a nitrate-
nitrogen concentration not to exceed 10 mg/L  (at site  boundary).
     8.3.5  Site Investigation


A  preliminary  investigation (see Section 3.5) of  the  lands  adjacent to
the  community  has  determined  that  about   11  000 acres (4 450 ha) is
available.   The  general topography of  the area  is shown in  Figure 8-1.
The  area  is  bounded  on  the  south by the  Susanna River,  which flows
westerly.  The existing water treatment  plant  and  intake,  and wastewater
treatment  plant  and  outfall are in the southwestern  corner.  The land
increases  in  elevation  from  about 100 ft (30 m)  above  mean sea level
near  the  Susanna  River  to  a  maximum elevation of  450 ft (136 m)  at
Clyde's  Saddle.  The surface slopes in  the range  of 1  to  4%,  although a
relatively flat area of 0 to 2% occurs in the  eastern portion.
          8.3.5.1  Soil Description
The  type  and  location  of  agricultural  soils  as  described  in the SCS
report  for  the  study area include Hunt clay  (HpG),  Hanover  loamy sand
(Hn), and Bomoseen sandy clay loam (BsN), as  shown  in  Figure 8-2.
The  Hunt  clay  is  a red-brown clay with a  thin  surface mantle of silt
loam.   Drainage  is  very poor with permeability  of  less than 0.2 in./h
(0.5  cm/h).  It is fair to good for grasses  and legumes; poor for grain
and seed crops and hardwood trees; and not suited  for coniferous trees.


The  Hanover  loamy sand is a well-drained soil with  a distance of 10 ft
(3  m) or more to the water table.  The permeability  is at least 3 in./h
                                    8-4

-------
00
 i
in
                                                                  FIGURE  8-1


                                                             GENERAL TOPOGRAPHY
                                                             WATER

                                                         TREATMENT PLANT
                                             WASTEWATER

                                              TREATMENT

                                  OUTFALLOO    PLAN
                           1  in.= 2.54  cm


                           1  ft = 0.305 m

-------
oo

CTl
                                                                FIGURE  8-2

                                                        AGRICULTURAL SOIL MAP
                                                                                            0     2000   4000
                                                                                             •

                                                                                             SCALE IN FEET
                              = SOI L BORINGS,  BsN
                                                 BOMOSEEN SANDY  CLAY LOAM,  Hn- HANOVER LOAMY  SAND, HP6-HUNT CLAY,

-------
(8  cm/h).    It   is   fair   to   good  for grain, seed crops, grasses, and
legumes; good for hardwoods, and  fair for coniferous trees.


The  Bomoseen  sandy  clay  loam is  well  drained, underlain by fine sands
with  10 ft (3 m) or  more to groundwater^  The permeability is 0.6 in./h
(1.5  cm/h).  It  is good for grain, seed, grass, legumes, and hardwoods;
and  fair  for  conifers.   A   descriptive  summary  of  the  soil types,
including  system suitability and  available  area,  is  presented  in
Table 8-3.
                                 TABLE  8-3

                   AVAILABLE  LAND  AREAS BY SOIL TYPE'
Soil
type
BsN-1
BsN-2
Hn
HpG-lb
HpG-2c
Soil
description
Sandy clay loam
Sandy clay loam
Loamy sand
Clay
Clay
Maximum
slope, %
2
3-4
3
2
3-4
Permeability,
in./h
0.6
0.6
3
<0.2
<0.2
System suitability
jSlow rate
Slow rate
Rapid infiltration
and slow rate
Overland flow
Overland flow
Total
Available
acres
4 240
330
1 340
1 230
4 020
11 160
       a.  Data from SCS report.
       b.  Area between 100 and 200 ft contours (half clear, half brush, and woodland).

       c.  Area above 200 ft contour (all brush and woodland).

       1 acre = 0.405 ha
       1 ft = 0.305 m
The  general  soils  evaluation   shows  that within the study area, there
exist soil types that  appear  to  be  suitable for all  three land treatment
processes.   Further assessment  of  their suitability requires additional
information on the subsurface geology.
          8.3.5.2  Soil  Borings
Well  logs  or other  information  on  the soil  profile were not available.
Consequently,  twelve   preliminary   soil   borings  were made as shown in
Figure 8-2 to confirm the  SCS  soil map. The results from the boring logs
show  that  groundwater was  encountered at the single drill hole  (No. 1)
and  that  the  depth  to bedrock  varied from a minimum of 20 ft (6 m) at
borings Nos. 4 and  5  to a  maximum of 70 to 80 ft (21 to 24 m) at borings
Nos.  1 and 8.  The underlying geology is a mixture of sands and gravels
with  clay  and  fine   sand  occurring at various depths without hardpan
layers.  The borings  at the  lowest elevations have the greatest depth to
                                     8-7

-------
bedrock,  with  decreasing  soil   depth  as  the  elevation increases.   The
subsoil geology has equal  to or greater  permeability than the  upper  soil
horizons.
          8.3.5.3  Vegetative Cover


The  vegetative  cover  is  important as  an  indicator of the  growth con-
ditions for a soil  type and as a factor  in determining costs  of clearing
and  other  site  preparation.  As  shown  in  Figure 8-3, in  the  eastern
part  of  the study area, there are open  lands  and native grasses on the
Bomoseen  sandy  clay  loam.  In the southwest  corner of the  study area,
there  is  previously  cleared land on Hanover  loamy sand and Hunt clay.
In  the  rest  of  the  study area  (proceeding  northward towards Clyde's
Saddle),  there  is  a  wooded area of brush and  trees, mostly underlain
with Hunt clay.
8.4  Process Alternatives


     8.4.1  Slow Rate System
The  initial  determination of the required field area is made using  the
annual  water balance:

                        Pr + Lw =  ET +  Wp  + R            (8-1)


where Pr  =  precipitation, ft/yr  (cm/yr)
      Lw  =  wastewater hydraulic  loading,  ft/yr  (cm/yr)
      ET  =  evapotranspiration, ft/yr  (cm/yr)
      Wp  =  percolating water, ft/yr (cm/yr)
       R  =  runoff,  ft/yr (cm/yr)


In  this case, runoff of applied water  will  be  retained and thus  will  be
considered  negligible.   The  relationship  between  precipitation   and
evapotranspiration  is  given  in   Table   8-1.    Precipitation  exceeds
evapotranspiration by 2.1  ft/yr (64 cm/yr).   Wastewater applications  are
scheduled for periods when the mean air temperature is above 32°F (0°C),
approximately from March 25 to November 3  (Table   8-1).   This   32 week
application  season  will   avoid  extreme  temperatures and frozen ground
conditions,  will ensure some crop response, and  necessitate 20 weeks  of
storage  within the design year.   The percolating water can be estimated
from Figure  3-3 using  the permeability value  of 0.6  in./h (1.5  cm/h)
for  the  Bomoseen  sandy  clay loam.   A  conservative rate of about  3.5
in./wk  (8.9  cm/wk)  is chosen because  crop production is planned. This
value  is  multiplied  by  the  32  week  season  to determine the annual
loading.

              (3.5 in./wk)  (32 wk/yr) * 12  in./ft = 9.3 ft/yr
                                  8-8

-------
CO
l
                                                              FIGURE 8-3

                                                      EXISTING VEGETATIVE COVER
                                                                                              0    2000    4000
                                                                                                   ml	^
                                                                                               SCALE  IN FEET
                                                                                                OPEN LAND
                                                                                               NATIVE GRASSES

-------
The total liquid loading would be reduced by the 2.1  ft/yr (64 cm/yr)  of
excess  precipitation  (Table  8-1)  for a resultant loading of 7.2  ft/yr
(216 cm/yr).  The required field area is then calculated to be:

                                F =  3-06 Q              (8-2)
                                      I
                                      Lw


where  F = field area, acres
       Q = annual wastewater flow,  Mgal/yr
      Lw = wastewater loading,  ft/yr

                              F = 3.06 (10H365)
                                       7.2

                              F = 1 551  acres

                            say = 1 600 acres

An  examination  of  the  soil   classification data and soil  boring  logs
shows  that  the  soils  classified as BsN  and Hn would be hydraulically
suitable  for  slow  rate  systems.   These  soils, as  located  along the
Susanna  River  and  east of Clyde's  Saddle (Figure 8-2),  comprise 5 910
acres (2 387 ha) (Table  8-3) of  suitable   land.  Thus,  it appears  that
the  slow  rate  process would be potentially feasible  for this location
and should be investigated further using  a  nitrogen balance (see Section
8.7.1) to determine if groundwater criteria can be satisfied.


     8.4.2  Rapid Infiltration System
The   determining   factor   in   hydraulic    application   is   the   soil
permeability.  The  Hanover  loamy sand has  a  permeability   of  at  least
3  in./h  (8  cm/h),  so  a wastewater application rate of  25  in./wk (64
cm/wk)  is estimated from Figure  3-3.  Based   on  a 52 wk/yr  operation,
this  results  in  an  annual  application rate of 110 ft/yr (33.5 m/yr).
The wetted field area can be estimated in the  same manner as a slow rate
system,  giving  a  required  wetted  field  area of 100 acres  (45 ha)  as
follows:

                    F = (3.06M3 650)/110 =  100 acres
The  alternate  flooding  and drying cycle can be accomplished by  having
multiple  basins,  with  a  set  of  basins  being flooded for 4 days  to
promote  good  denitrification followed by an 8 day drying period.   This
operational  schedule  results  in  approximately one-third of the  field
area  (8  or  9  basins)  being flooded and two-thirds (16 or 17 basins)
being  rested  at any given time.  Approximately 1 350 acres (614  ha)  of
suitable soil exists, so this alternative should be investigated further
to determine if it can satisfy water quality requirements.
                                   8-10

-------
     8.4.3  Overland Flow System
Overland  flow  systems  require  slopes  from  2  to  8%  on relatively
impermeable soils.  The almost continuously wet field conditions are not
conducive  to  normal  forest or agricultural cover, but usually require
special  grasses.   Nitrogen removal is dependent on complex biochemical
responses  in  addition to crop uptake.  These biochemical responses are
temperature dependent so there are climatic constraints on overland flow
systems.
Since  terraces  having  appropriate slopes and dimensions can be formed
and  proper  soils  are  available,  it  should  be  possible  to  apply
approximately 8 in./wk (20.3 cm/wk) of lagoon effluent during the summer
growing  season  and  approximately  half  that  amount,  4 in./wk (10.2
cm/wk),  in the spring and fall (Section 5.1.4.1).  Since winter storage
requires some form of treatment oxidized wastewater will be  applied  to
the slopes.  Operational experience will dictate the degree of oxidation
required; it may be possible to shut down all of the aerators during the
summer.  The application schedule and storage requirements are presented
in  Table  8-4, using the number of days with mean temperature less than
32°F (0°C).  The results give a design application of 17.8 ft/yr (5.4 m)
and a storage requirement of approximately 142 days.
                                TABLE 8-4
           DETERMINATION OF OVERLAND FLOW APPLICATION SCHEDULE
                         BASED ON CLIMATIC DATA3
Total No.
of days in
Time period time period
Nov 16 -
Apr 21 -
May 1 -
Oct 1 -
Total
Apr 20
Apr 30
Sep 30
Nov 15
156
10
153
46
365
No. of days
with mean
temperature Applicatio
532°F period, d
133
0
2
7
142
23
10
151
39
223
Application schedule
No. of wks
3.3
1.4
21.6
5.6
31.9
in./wk applied, in.
4 13.2
4 5.6
8 172.8
4 22.4
214.0
    a. Based on worst year in 10, from Table 8-1.

    1 in. = 2.54 cm
The  required  field area is 627 acres (254 ha), as computed by the same
method used for the slow rate system:

                      F = (3.06H3 650) = 627 acres
                           17.8 ft/yr
                                   8-11

-------
An  examination  of  the soils data indicates  that the area north  of  the
water  treatment  plant  on  the  lower  slopes   of  Clyde's Saddle will
probably be suitable.  Between elevation 100 ft  (30 m) and elevation  200
ft  (61  m) there is at least 1  230 acres (497 ha) of soils suitable  for
constructing an overland flow system,  hence'overland flow should also be
considered further.
8.5  Preliminary Performance Estimate


     8.5.1  Slow Rate System
The  capability  of  the  slow  rate   system  to  meet Case  1  groundwater
standards  was determined by assuming  a  10  mg/L aesign concentration  for
nitrate-nitrogen.   Removal   of  phosphorus  is excellent,  with  expected
removals greater than 99%, even though a phosphorus limit does not  exist
for  drinking  water.  The concentrations of BOD  and suspended solids in
the  percolate  should be less than 1  to 2  mg/L,  and pathogenic  organism
removal  by  the  Bomoseen sandy clay  loam  should be complete within  the
upper 2 ft (0.6 m) of the soil.
The  limiting  design  criteria  is  nitrogen.   Based on  existing  system
performance  (see  Chapter  7), the concentration  of nitrate-nitrogen  in
the  slow  rate  system percolate will  be  better than the 10  mg/L  design
value.   In  addition, the design for 10 mg/L percolate nitrate-nitrogen
concentration  is  conservative,  because   significant dilution   of the
percolate nitrate-nitrogen will most likely occur  as the  percolate water
mixes  with  the  underlying native groundwater.  Also, design  flows are
assumed  for  1990, so initial  applications will be less, and subsequent
nitrogen  performance better.  Seasonal variations in performance  should
be  satisfied by variable monthly applications.  The monthly  application
criteria will be developed if slow rate systems  are most  cost effective.
     8.5.2  Rapid Infiltration System
The  treatment  performance  of  a  rapid  infiltration  system  should  be
assessed because design applications are usually  determined  by  hydraulic
considerations  rather  than  wastewater  constituent applications.  For
this  example,  the  performance  should  be  evaluated   for groundwater
discharge,  as  well   as  surface  discharge.   The soil  permeability and
subsurface geology are both suitable for groundwater discharge.


The  total  nitrogen   applied to the land in a rapid infiltration  system
can be estimated from Equation 5-3:

           Ln = 2.7 Cn Lw
              = (2.7)(28 mg/L)(110 ft/yr) = 8 316 lb/acre-yr
          say = 8 400 lb/acre-yr (9 410 kg/ha-yr)
                                   8-12

-------
The nitrogen  is  rapidly  converted  from the applied organics and ammonium
form to nitrate-nitrogen.   The  principal  removal  mechanism is biological
denitrification  of   nitrate-nitrogen,  although  volatilization and crop
uptake  (if   vegetation   is  used)   can  add  to  the estimated 50% total
removal.   The   estimated  percolate nitrogen amounts to 4 ZOO lb/acre-yr
(4 700  kg/ha-yr)  and will  move with a percolate  volume of 112 ft/yr (34
m/yr)  [110   ft  (33.5  m)   applied  wastewater  and  2  ft  (0.6 m) net
precipitation].    The average concentration of nitrate-nitrogen would be
approximately 4  200/(2.7)(112)  = 14 mg/L.   This concentration is greater
than the assumed design  criteria of 10 mg/L total  nitrogen for percolate
and greater than the  6 mg/L total  nitrogen criteria for river discharge.
Although   the other discharge criteria, i.e.,  phosphorus, BOD, suspended
solids,    and   pathogens,    would   be   adequately   satisfied,  rapid
infiltration,  by  itself,  will  not satisfy the nitrogen design criteria.
.Further  investigation  would  be   necessary  to  determine the degree of
mixing  and   dispersion   that  would  occur in the groundwater under the
site.  For  this example,   rapid  infiltration is  not discussed further,
except in combination with  overland flow.


     8.5.3  Overland  Flow  System


The  average  total nitrogen concentration of an  overland flow runoff is
expected   to  be  about   3 mg/L (see Table 2-3).   Existing overland flow
systems have  shown that  total nitrogen removals (mass basis) have varied
from  75   to  90%  for systems operating with an application period of b2
wk/yr.  The principal  nitrogen  removal  mechanisms are crop  uptake and
nitrification-denitrification on the  soil surface; these mechanisms are
adversely  affected by low winter  temperatures.   Therefore,  it would be
reasonable  to expect a  90% nitrogen removal  for  a system operating witH
an application   period of  32 wk/yr.   For the estimated  hydraulic appli-
cation of  17.8  ft/yr (5.4 m),  the total  applied  nitrogen (from Equation
5-3) is (2.7)(28)(17.8)  =  1  346 lb/acre-yr (1  509 kg/ha-yr).  With a 90%
removal, 135  lb/acre-yr  (151  kg/ha-yr) is collected in the  runoff.  The
final concentration   is  dependent  upon the water  balance,  so inputs and
outputs are given:
                     Applied wastewater             17.8  (5.4)

                     Percolate loss3               -1.4  (0.4)

                     Precipitation-evapotranspirationb  +1.7  (Q.5)
                      Net runoff                  ia.1  (5.5)


                     a. Assume 8% loss for HpG soil.
                     b. Estimate for application period.
The  design   runoff nitrogen is estimated to be all in the nitrate form.
From   a mass  of  135 lb/acre-yr (151  kg/ha-yr) and a volume of 18.1 ft/yr
                                    8-13

-------
(4,4 m/yr),  the  concentration is determined as follows:  135/(2.7)(18.1)
=  2.8  mg/L.    This  concentration  meets  both  surface  and  subsurface
nitrogen criteria.


Phosphorus   removal,    however,   is  usually  50% since  the  wastewater
contact   with    the   soil    is   relatively   limited    (see   Section
5.1.4.5).    At the  design application rate of 17.8 ft/yr (5.4  m/yr),  the
applied  phosphorus  is  P = 2.7  CL   = (2.7)(8)(17.8) =  385  lb/acre-yr
(431  kg/ha-yr),  of which 192 lb/ac?e-yr (215 kg/ha-yr) can be  expected
to  run  off.    This  would  correspond  to  a  runoff  concentration of
192/(2.7){18.1)   =   3.9  mg/L.   The phosphorus concentration  is greater
than  the  river discharge standard of 0.1 mg/L, so overland  flow alone
would  not be allowed  for surface discharge.  In addition, overland flow
alone would  not  meet discharge criteria for suspended solids.


To  make  overland  flow a feasible alternative for this example,  it will
be  combined in  series  with  rapid infiltration.  The combined system
would  depend  on  the  former  for  nitrogen and BOD removal  and on  the
latter  for  suspended  solids,  microorganisms, and phosphorus  removal.
The  rapid   infiltration  basins  would  be  designed for  the  18.1 ft/yr
seasonal net runoff from the overland flow slopes:
           Net overland flow runoff = (18.1 ft/yr)(627 acres)  = 11 350 acre-ft/season
                   RI application =11 350 acre-ft/season *  32 wk/season = 355 acre-ft/wk
          For a 100 acre basin area,
            weekly application rate = 355 * 100 x 12 = 42.6 in./wk
        From Figure 3-3, the maximum                               .
               weekly application = 50-70 in./wk; thus, 42.6 in./wk is satisfactory.
The  hydraulic  capacity  of the soil  would govern design rather than  the
loadings of wastewater  constituents.   Discharge would be to groundwater,
and would eventually  appear as a seep to the river (nonpoint discharge).
A summary of the  preliminary assessments is presented in Table 8-5.   The
slow  rate  and   the   combined  overland  flow  and  rapid  infiltration
processes  are  capaole   of  providing satisfactory wastewater treatment
with  the  tabulated   application rates and land areas.  A cost estimate
should  be  determined  at this time to decide which option provides  the
most  cost-effective   treatment  and  should  be considered for detailed
design.   In addition, slow rate systems have three distribution options
that should be evaluated on a cost-effectiveness basis.
                                   8-14

-------
                                 TABLE  8-5

                       SUMMARY OF DESIGN  INFORMATION
                        FOR TREATMENT ALTERNATIVES
Treatment
Alternatives
Slow rate (flood,
center pivot or
solid set)
Overland flow
followed by rapid
infiltration
Overland flow
Rapid infiltration
Design
flow,
Mgal/d
10
10
10
Annual Wastewater
application
Period
wk
32
32
32
, Total ,
ft
7.2
17.8
113.5
Avg weekly
application
rate, in.
2.7
6.7
42.6
Application
area, acres
1 600
627
100
Length of
storage,
d
140
140
Storage
area,
acres3
360
36U
Treatment
lagoon,
acresb
15
15
Total
area
acresc
2 170 •
1 100
110
a.  Based on 10 Mgal/d flow and 12 ft working depth (see Section b.7.1.5).
b.  Based on 7 days detention at 10 Mgal/d, 15 ft working depth.
c.  Includes 10% for roads, buildings, and miscellaneous.

1 Mgal/d = 43.8 L/s
1 ft = 0.305 m
1 in. = 2.54 cm
1 acre = 0.405 ha
8.6  Cost  Comparison
The procedures  to calculate capital, and operation  and maintenance costs
have 'been   published  [1].  Tabulations of  the  results are presented in
Table  8-6   to   show  differences  due  to   type of treatment system and
distribution system.  The cost comparison is made solely to compare land
treatment   systems.    Each  system  will  usually  contain  a collection
system,^collection pumping, preapplication treatment,  and administrative
facilities;   these  are  not  included in the  comparison since the added
capital  and operation  and  maintenance  costs  should  be  identical.
Additional   comparison  to  a  conventional  treatment alternative would
require  inclusion  of all costs before comparisons with total treatment
system would be  made.                                               ";


The  total   costs  in  Table 8-6 include unlined storage, site clearing,
site  leveling,   distribution system, distribution  pumping (Alternatives
1-4); tailwater  return (Alternative  1);  overland   flow   terrace  con-
struction,  runoff  collection,  and  open  channel  transmission from the
overland flow to the rapid infiltration site (Alternative 4).


A  slow rate system, utilizing center pivot  distribution, has the lowest
relative  cost   for   this  design  example.  The costs generated are not
discussed   further  since  their  purpose was  only  to  provide a relative
                                    8-15

-------
cost  effectiveness  for the general  conditions  as  described  in Table 8-6,
and   as  developed   in  the text  (Sections 8.4 and 8.5).  The slow rate,
center  pivot  alternative  will   be  further   developed  to  provide the
preliminary system  design.
                                   TABLE 8-6

          RELATIVE  COST COMPARISON,  DESIGN EXAMPLE  ALTERNATIVES'
                          Land     Total   Amortized  Operation and
                          area,   capital   capital    maintenance   Total     Municipal.
      Alternative   System type  acresb  cost, $  cost, $/yr   cost, $/yr  cost, $/yr cost, $/yrc
1

2

3

4


Slow rate,
flood
Slow rate,
center pivot
Slow rate,
solid set
Overland flow
and rapid
infiltration
2 170

2 170

2 170

1 210


8 583 770

8 232 770

10 624 120

8 495 500


756 230

725 310

935 990

748 450


202 750

205 720

186 520

214 000


958 980

931 030

1 122 510

962 450


391 810

387 050

420 520

401 110


      a. Based on unique or variable land treatment components. Items that are common to and have
        equal costs in all alternatives are not included.

      b. Actual area is determined in the final layout.

      c. Computed as 25% capital and 100% operation and maintenance costs.

      1 acre = 0.405 ha
8.7  Process Design
In  this  particular  example, the  slow rate, center pivot alternative was
found  to  be more cost  effective than  the treatment system alternative of
overland   flow followed by rapid  infiltration; under other circumstances
the  reverse  may  be   true.  For purposes of illustrating   the required
design  procedures, both treatment system alternatives will be  described.
     8.7.1   Slow Rate
The  development  of  the slow rate  process design  includes an  assessment
of   (1)   the  hydraulic   loading  criteria,   (2)   the annual and monthly
nitrogen   loadings, and  (3) phosphorus and trace metal loading criteria.
Also   included   is   a   discussion   of  (4)   preapplication    treatment,
(5)  storage design criteria, and  (6)  distribution  system criteria.
                                     8-16

-------
         8.7.1.1  Hydraulic Loading


For slow rate systems, net runoff can be assumed to be negligible.   From
Table  8-1, the  total  annual   precipitation  (Pr) of 50.2 in./yr   (128
cm/yr) minus the total annual  evapotranspiration (ET) of 25.1  in./yr (64
cm/yr)  yields  an  annual net water excess of 25.1 in./yr (64 cm/yr)  or
2.1 ft/yr (0.6 m/yr).  Thus Equation 8-1 becomes:


                             Wn = Lw + Pr - ET
or
                             WD = Lw + 2.1  ft/yr
The  amount  of  percolating  water  (Wp)  resulting  from  the  applied
effluent (Lw) has a significant effect on the allowable nitrogen loading
(Ln)> as is illustrated in the following section.
         8.7.1.2  Nitrogen Loading
The  annual nitrogen loading can be estimated from procedures in Section
5.1.2.2, as described below:
     The annual nitrogen balance, using Equation 5-2, is:


                         Ln = U + D + 2.7 Wp Cp         (5-2)
where Ln = wastewater nitrogen loading, Ib/acre-yr (kg/ha-yr)
       U = crop N uptake = 325 lb/acre-yr (364 kg/ha-yr) for Reed
           canary grass (Table 5-2)
       D = denitrification = 0.2 Ln (assume denitrification to be
           20% of applied nitrogen)
      Wp = percolating water = Lw + 2.1 ft/yr
      C  = design percolate N concentration = 10.0 mg/L
                                  8-17

-------
Therefore,
                Ln = 325 + 0.2 Lp + (2.7)(LW + 2.1M10),
and  the  relationship  between  the  nitrogen loading  and the  hydraulic
loading (from Equation 5-3) is:
                             Ln ' 2'7  Cn
where Cn =     applied nitrogen concentration,  mg/L

      L  =     wastewater hydraulic  loading,  ft/yr
       W
Therefore, at Cn = 28 mg/L (from Table 8-2),
                              Ln - 75'6  Lw
or  .

                                      13  Ln
Now  with  two equations and two unknowns,  the  nitrogen  balance  equation
can be solved:
     L  = 325 + 0.2 Ln + (2.7)(LW + 2.
     Ln = 325 + 0.2 Ln + (2.7)[(0.013 Lnj
     Ln = 325 + 0.2 Ln + 0.351  Ln + 56.7
0.45 Ln = 381.7
     Ln = 848 lb/acre-yr


The  complete  solution for a design percolate  nitrogen  concentration  of
10 mg/L is as follows:

1.  Wastewater nitrogen loading = Ln =  848 lb/acre-yr
2.  Wastewater hydraulic loading = Lw = 0.013 Ln  = 0.013 (848)  =11.0  ft/yr
3.  Percolating water = Wp = Lw + 2.1 = 13.1 ft/yr
4.  Denitrification = D = 0.2 Ln = 170  lb/acre-yr
5.  Percolate nitrogen loading = Pn = 2.7  CpWp  =  2.7(10)(13.1)

                              = 354 lb/acre-yr

6.  Required field area = F = 3.06(365) Q  = ] ]j8 (10) = 1  015  acres
                                 Lw          11.0
                                   8-18

-------
The  slow  rate system design is based on maximum nitrogen uptake by the
vegetation.   For  this design, a cool season forage grass, such as Reed
canary  grass,  is  chosen  since  it will provide an estimated nitrogen
removal  of 325 lb/acre-yr (364 kg/ha-yr) and provide a year-round cover
for  maximum  infiltration,  minimal   soil  erosion  after 'harvest  (in
contrast  to an annual crop), and nitrogen response at the beginning and
end of the growing season as a result of an established root system.


The  procedure  to  determine  the monthly nitrogen balance accounts for
monthly  climatic  influences.   Thus,  greater  wastewater applications
occur  when  more  nitrogen  is  needed  by  the  vegetation and greater
microbial activity occurs.


In  order  to  determine  the  optimal  system  design loadings,  monthly
wastewater  applications  (values  for  L )  were  chosen  (by trial and
error) to the nearest inch, so that the percolate nitrogen concentration
(C )  was  less than, or equal to 10.0 mg/L.  For the first cut estimate
or  monthly  values  for  L ,  divide  the  annual  wastewater hydraulic
loading  (from above) by the number of months in the application season.
For this example, the first trial value for  Lw  for the months of April
through  October  would  be 11 ft/yr x 12 in./ft *  7 mo/yr = 19 in./mo.
For  the cool weather months of March and November (at the beginning and
end   of   the   growing   season),  a  wastewater hydraulic loading  of
1 in./month was assumed.
The  monthly  nitrogen  loading  may  be  calculated using the following
equation:

                             Ln = 0.227 CnLw              (8-3)


where L  = wastewater nitrogen loading, lb/acre-month (kg/ha-month)
      C  = applied nitrogen concentration, mg/L
      L  = wastewater hydraulic loading, in./month (cm/month)
       w


The estimated denitrification is calculated as 20% of the total  nitrogen
applied  resulting  in  an annual loss of 147 lb/acre-yr (165  kg/ha-yr).
Crop  nitrogen uptake was estimated at 325 Ib/acre-yr (364 kg/ha'yr)  and
distributed monthly by the monthly fraction of the total evapotranspira-
tion occurring  during  the growing season, which can be estimated to  be
the  months  of April through October.  This assumes that plants utilize
nitrogen  and  water at similar rates.  Whenever possible, estimation  of
the  monthly  variation  of  crop  nitrogen  uptake should be  refined  by
consulting the local  agricultural extension service.  Percolate nitrogen
(P )   was   computed   as   the   difference  between  application   and
denitrification  plus  crop  nitrogen  uptake.   The  percolate nitrogen
concentration   (C )    was  computed  from  monthly  percolate  nitrogen
(P )(lb/acre)  andp total   percolate   volume  (W ).   To  calculate  the
                                   8-19

-------
monthly   percolate nitrogen  concentration  (C  ),   the following  equation
can be used:
                               Pn  =0.227 CpWp
                                                                (8-4)
where Pn  =  percolate nitrogen  loading, lb/acre'month (kg/ha-month)
            percolate nitrogen  concentration, mg/L  (10 mg/L limit)
            percolating water,  in./month (cm/month)
      WP =
The result  of the monthly nitrogen  balance are presented in Table 8-7.


                                  TABLE 8-7

             MONTHLY DESIGN NITROGEN BALANCE, SLOW RATE SYSTEM




ii \
(Pr - ET) "-w1 Wastewater
Net monthly Applied nitrogen ^°
excess
Month water, in.a
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
4.
4.
4.
3.
4.
3.
0.
-1.
-1.
-0.
0.
2.
Annual 25.
a.
b.

c.
d.
e.
f.
g.
h.
i.
From Table
0
2
3
5
8
2
7
3
6
3
9
7
1
8-1.
Highest possible
of trials)
Lp = 0.227

CnLw'
Leaching
(U)
' Crop N
(Wp)
Percolate
wastewater, loading., Denitrification, uptake, water,
in.b Ib/acreC lb/acred Ib/acre in.e
1
0
0
0
1
9
15
20
24
20
16
11
117

volume

Cn = 28
h 6



h 6
57
95
127
153
127
102
70
743

(to nearest in.) without

mg/L.
1



1
11
19
25
31
25
20
14
147

exceeding 10


• • .




19
43
62
73
58
44
26
325

mg/L


5
4
4
3
5
12
15
18
22
19
16
13
142

.0
.2
.3
.5
.8
.2
.7
.7
.4
.7
.9
.7
.1

1n percolate




(Pn) (Cp)
Percolate Percolate nitrogen
nitrogen. concentration,
lb/acref mg/L9
5



5
27
33
40
49
44
38
30
271

(found


4



3
9
9
9
9
9
9
9
8

.4



.8
.7
.3
.4
.6
.8
.9
.6
.41

after a series




D = 0.2 Ln.
WP ' Lw +
pn = Ln -
Pn = 0.227
Pr - ET.
D - U.
cpwp;
Assume 1 in./wk
Computed as the

CP = P

n/(0.227)(Wp)
application at beginning and end
average
of the monthly values.














of growing season.
Conservative
since
nonapplication season rainwater
   percolation and groundwater dilution will reduce yearly average total percolate nitrogen.

1  in. =2.54 cm
1  Ib/acre =1.12 kg/ha
                                    8-20

-------
The  monthly  design  nitrogen  balance  results in an annual  wastewater
application  of  117  in./yr  or 9.7 ft/yr (3.0 m/yr), which is slightly
less  than 11.0 ft/yr (3.3 m/yr) in the previous annual assessment.   The
wetted  field  area  should  be  adjusted  to  account  for  the  lesser
application, so the required application area is:
          P _ 3.06(365) Q

                 Lw
                  118 (10)
                   9.7
rather than 1 015 acres (410 ha).

The  permeability  for  the soil  surface (infiltration rate)  and subsoil
can  be evaluated on the basis of the maximum monthly liquid  application
to  the soil surface.  During July, the wastewater application of 24 in.
(60 cm) and mean precipitation of 3.8 in. (10 cm)  and evapotranspiration
of  5;4  in. (14 crn) add up to a monthly infiltration of 22.4 in./mo (57
cm/mo).  On a weekly basis, the maximum hydraulic  loading would be about
5.6  in./wk  (14  cm/wk).   For the Bomoseen sandy clay loam  with a soil
permeability  of  0.6 in./h (1.5 cm/h) and a perennial forage cover, the
total  application  could  be  infiltrated  within  about 9 hours.   This
represents  less  than 6% of the total time in a week, so an  application
schedule based on equipment capacity can be determined.
          8.7.1.3  Other Mass Loadings
The  mass  application of phosphorus and trace metals to the site can  be
assessed  to determine if they would limit total  wastewater applications
over  the  20 year design life of the project.  The phosphorus criterion
is   based
vegetation,
trace  metal
project  for
for elements
on  the  total   mass  application,   phosphorus  removal   in
and  soil   retention  by adsorption and precipitation.   The
criterion is based on mass application over the life  of  the
 elements  retained in the soil,  and applied concentrations
that are not retained.
At  the  annual  application  rate of 9.7 ft/yr (3.0 m/yr)  and the total
phosphorus  concentration  of  8 mg/L (as P), the annual  application is:
(2.7)(8)(9.7)  =  210  lb/acre-yr (235 kg/ha-yr).  The Reed canary grass
will  remove  40 lb/acre-yr (45 kg/ha-yr) (Table B-l) during harvest,  so
the  net  application to the soil is 170 Ib/acre-yr (190 kg/ha'yr).  The
sandy  clay  loam  soil  will  have excellent removal of phosphorus as a
result  of the clay content.  The 3 400 Ib/acre (3 811 kg/ha) phosphorus
application  over  20 years can be completely adsorbed in the top 22 in.
(56  cm)  of  the  soil  with  a  5  day adsorption capacity of 50 mg of
phosphorus per 100 g of soil and a bulk density of 1.3 g/cm3.  This is a
conservative  estimate  since  it has been estimated that the phosphorus
retention (including chemical precipitation) may be at least double that
measured by the 5 day adsorption test.
                                   8-21

-------
The  mass   application  of  trace  metals  should  not   pose any further
limitations  at  the proposed  site.   For the applied concentrations, the
mass   applications  are  below  the   recommended  maximum  for  use  on
agricultural  soils (Table 8-8).
                                  TABLE  8-8

                 TRACE METALS  IN  SLOW RATE DESIGN EXAMPLE
Concentration in Concentration Mass
raw wastewater, applied to application
Element mg/L land, mg/L lb/acrea
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Silver
Zinc
0.01
0.03
0.22
0.01
0.001
0.03
0.001
0.31
0.008
0.02
0.10
0.005
0.001
0.02
0.001
0.20
4
10
52
2.6
0.5
10
0.5
105
Maximum
loading
, criteria,
lb/acreb
8
82
164
4 080
d
164
e
1 640
EPA
Drinking Water
Standard, mg/l_c
0.01
0.05
1.0
0.05
0.002
No standard
0.05
5.0
          a.  On the basis of 9.7 ft/yr and 20 yr life.  Example;  Cd
             = (2.7)(0.008)(9.7)(20) = 4.

          b.  From Table b-4.
          c.  From Table 3-4.

          d.  No suggested limit since retention is very high and applied concentrations are
             below drinking water standard.

          e.  No limit since most applications are too small in comparison with drinking
             water standard.

          1 lb/acre= 1.13 kg/ha
           8.7.1.4  Preapplication Treatment
Preapplication  treatment   is  included as a unit  process in this design
example as a means of odor  control  for the 20 week winter storage period
and   for  a  reduction   of   suspended solids to minimize clogging in  the
distribution  system.    The  treatment removals of nitrogen, phosphorus,
and    other  wastewater  organic  and  inorganic   constituents  are   not
dependent  on  a  specified level  of treatment before application to  the
land,   so  partial  oxidation of wastewater organics should be adequate.
The   long-term  storage  pond  should  provide for additional wastewater
treatment during the retention time of up to 20 weeks, so preapplication
treatment by aerated lagoons to reduce BOD down to a concentration of 60
mg/L   should  be  adequate.  Other processes exist to oxidize wastewater
organics  before  application  to the land, but for the purposes of this
example,   aerated   lagoons  are  considered  the  most  cost-effective
alternative.   A  further  reduction in BOD will occur during the 20 week
storage period.
                                     8-22

-------
Detailed design procedures for aerated lagoons are covered elsewhere [2]
and will not be repeated herein.  Experience with lagoons indicates that
multiple  cells  offer  operating and maintenance advantages.  Since the
site is in a northern climate, extra time must be provided to compensate
for  the  slower  reaction  rates  in the winter.  A 4 cell system, with
parallel  units, designed for a total detention of 6 days should provide
the desired level of treatment during the winter months at this site.


          8.7.1.5  Storage Lagoons


The  required  volume,  area,  and  depth  for the storage lagoon can be
calculated in a manner similar to that used for the aerated lagoon.  The
climatic  data  were used to calculate a 20 week storage, which resulted
in  a total storage capacity of 1.4 XH 109 gal (5.3 x 109  L).   This is
equivalent  to a volume of 1.87 x  10   ft3  (5.3  x 106  m3);   so  360
surface  acres (164 ha)   is  required  for  storage at a depth of 12 ft
(3.7 m).  The final design should allow an additional 3 ft (0.9  m)  for
freeboard,  for  a  15  ft (4.6 m) total  depth in storage.  Further, the
storage  lagoon  should  be  divided  into multiple cells to reduce wind
fetch  and  wave generation.  The final design would consist of 4 basins
at  90  acres  each  or  3  basins at 120 acres each, depending on final
topography available for siting and construction.
          8.7.1.6  Location of Treatment and Storage Lagoons


The  open land to the east of the tree line in Figure 8-3 was identified
as  potentially  feasible  for  a slow rate system.  There is sufficient
land  for  location of the treatment and storage lagoons, as well as the
advantage of having all components of the system in proximity.  However,
the  soil characteristics would require lining of the lagoons to control
seepage.


Further   examination   of  the  topography  and  soils  data  indicates
significant  advantages  exist for a location in the general vicinity of
borings  No. 2 and No. 7, as shown in Figure 8-2.  Such a location would
permit  gravity  flow  of  the  raw  wastewater  to the highest possible
elevation  shown  on  the map, and the impermeable surface soils in this
area  could  be  stripped  and  used  to  line the treatment and storage
lagoons.   It would require clearing of approximately 375 acres (170 ha)
of brush and trees from the site.
          8.7.1.7  Slow Rate Distribution System
The  design of a mechanical  distribution system is usually determined  by
the  equipment  available  from  various  manufacturers.   However,  it  is
desirable  to  know  the number and size of units so that an estimate  of
                                   8-23

-------
unsprayed  areas between wetted  circles can be made.   The  costs  (Table
8-6)   were estimated  on the basis of a maximum sprayed area of  134 acres
(61   ha) per  sprinkler  unit, with the rotating booms typically  available
as multiples  of 100 foot lengths.


To  cover  the  required field  area of 1 150  acres (466   ha), 9 units of
134   acres  (61   ha)  each  will  be used.   Each unit has  a rotating boom
radius  of  about 1 300 ft (397  m).  The  total area required would be 15
to  20% greater, depending on  geometric layout of  the circles and  degree
of  end  area coverage  from manufacturer's  specifications; 2U%  should be
assumed,  so  the required area  for application is 1 380  acres  (560 ha).
The application frequency should be as high as possible,  again  depending
on manufacturer's specifications, but at  least 2 to 3 rotations per week
are   desirable   to minimize the  high instantaneous rates  needed to apply
all the wastewater to soil.
      8.7.1.8   Summary  for Slow  Rate System Design
A  summary  of   the principal  design factors for  the most cost-effective
alternative,  slow  rate  treatment  by   center   pivot   distribution, is
presented in  Table 8-9.
                                    TABLE 8-9

                  DESIGN  FACTORS,  SLOW RATE TREATMENT WITH
                           CENTER  PIVOT DISTRIBUTION
              Total annual wastewater application, ft            9-7
              Length of application season, wk                 32

              Length of storage, wk                        20
              Nitrogen balance
                Applied, lb/acre-yr                        74J
                Uenitrification, lb/acre-yr                   1*7
                Crop uptake, lb/acre-yr                      32b
                cercolate, lb/acre-yr                       271
                Avg monthly percolate nitrogen concentration, mg/L  b.4

              Preapplication treatment detention time, d
                Aerated lagoons                           &
                Storage lagoons (maximum)                    110
              Land required, acres
                Wetted area                              1 IbO
                Total field area (center pivot only)             1 38U
                Aerated lagoons                           15
                Storage lagoons                           3bU
                lotal (including lu* for miscellaneous)          1 98U

              Additional application criteria
                Maximum monthly infiltration volume (July), in./no  22.4
                fhosphorus retention (required soil volume), in.
                 Conservative                            22
                 Realistic                              11
                Trace metals                              Not restricting
               1 ft = U.JUb m
               1 Ib/acre =1.12 kg/ha
               1 acre = 0.405 ha
               1 in. = 2.b4 cm
                                        8-24

-------
     b.7.2  Combined Overland Flow and Rapid Infiltration


The  process design for the combined system of overland flow followed by
rapid  infiltration  is  presented  here.   Hydraulic  -loading rates  and
cycles and distribution systems are discussed.  Preapplication treatment
and storage requirements will be the same as for a slow rate system.


          is.7.2.1   Hydraulic Loadings and Cycles


The  overland  flow  system  will  be  loaded at 8 in./wk (20 cm/wk)  for
approximately  22  of the 32 week application period.  Applications will
be for 6 h/d on a 6 d/wk schedule.  This allows Iti h/d of resting plus a
full  day  of  resting  once a week.  This cycle is typical  of operating
systems (see Section b.1.4, 7.11, and 7.12).
During  the  period  from  October  to  May,  there will  be days when  the
temperature  will  be below freezing and storage will  be provided.  When
conditions  are  favorable in this time period, the overland flow system
will  be  loaded  at  4  in./wk  (10  cm/wk)   by  operating  6  h/d  for
approximately 3 d/wk.


The  rapid  infiltration system will receive  the treated runoff from  the
overland  flow  slopes.  Nitrogen removal  is  nearly complete in overland
flow,  so  the  rapid  infiltration  system  can  be managed to maximize
hydraulic  loading rates (rather than to optimize denitrification,  as is
the  case  when  rapid  infiltration  receives  a  primary  or secondary
effluent).  Thus, application will be for 2 days to a set of basins with
a  6  day  drying period.  Therefore, 42.6 in. (108 cm)  of water will be
applied  over  2  days followed by resting.  The water should infiltrate
within  a day after application ceases.  Using the procedure in Appendix
C,  field  testing  should  be conducted prior to final  design to verify
adequate  infiltration rates.  The flooding basin technique, as shown in
Figure  C-l, should be used for the determination of infiltration rates.
It  is  recommended  that  several  20  ft?  basins,  located  in repre-
sentative areas  of  the  site, be employed.   The resulting infiltration
rate  data  should  be  analyzed according to the procedure discussed in
Appendix C (Section C.3.1).


Soil  borings  at  the  proposed  rapid infiltration site should also be
examined to verify the lack of restrictive layers in the soil  profile.
          8.7.2.2  Distribution System


For  overland  flow,  the aerated lagoon effluent would be applied using
the  bubbling  orifice  (surface  application  technique  used  at Pauls
Valley,  Section  7.11).   The  application  would be at the top of  the
                                   8-25

-------
150 ft (45 m) long slopes.  The  slopes would be between 3 and 4%.    The
runoff  would  be  collected  in a series of ditches  and conveyed to  the
rapid  infiltration  basins.  Overland flow effluent  would be applied to
the rapid  infiltration  basins on a cycle of 2 days  wet and 6 days dry.
The 100 acres  of  basins  would be  divided into basins ranging in size
from  3 to 10 acres  each.  Four  sets of basins (A through D) with each
set containing about 25  acres  would  be  established.   For 2 days   the
application would be to set A, followed by sets B, C, and D in rotation.
In  actual  practice some basins will  have higher and  some lower infil-
tration rates and the  length  of  flooding and drying  can be  modified
accordingly.
b.8  References
1.   Pound, C.E.,  R.W.  Crites,  and D.A.  Griffes.  Costs of Wastewater
     Treatment  By  Land  Application.  Environmental  Protection Agency,
     Office of Water Program Operations.  EPA-430/9-75-003.  June 1975.

2.   Meteal f  &  Eddy,  Inc.  Wastewater Engineering.   Mew York, McGraw-
     Hill Book Co.  1972.
                                  8-26

-------
                               APPENDIX A

                                NITROGEN
A.I  Introduction
Application  of wastewater on land, as compared to the more common prac-
tice of  discharge  to  surface  waters,  has  a number of advantages  to
recommend it.  One of these is conservation of valuable resources in  the
form  of  contained  nutrient  elements.   Only  one  of  these nutrient
elements—nitrogen—is  considered here.  Where it is feasible to do  so,
it is much more logical  to use nitrogen, the production cost of which  is
continually  increasing,  in  the production of essential  food and fiber
rather  than  to treat it entirely as a waste.  Nearly all soils respond
to additions of nitrogen by increasing production; however, the require-
ments of  nitrogen  for  optimum  crop  production and the need to treat
large  volumes  of nitrogen-containing wastewater may not be in balance.
Nitrogen,applied to soils in amounts greatly in excess of crop needs  and
allowed  to  percolate to the groundwater may result in contamination  of
the  groundwater  through  leaching  of  nitrates  below  the root zone.
Nitrogen  transformations,  removal  mechanisms, and overall  removals  by
the land treatment methods are described in this appendix.
A.2  Nitrogen Transformations


     A.2.1  Nitrification
In  discussing removal of nitrogen from applied wastewater,  it is impor-
tant to  understand  something about the complex and interrelated series
of  nitrogen  transformations  that may occur in soils.   The predominant
form  of  nitrogen  in wastewater is usually ammonium, although some  ni-
trate is  also likely to be present if the preapplication treatment pro-
cesses have  included  one  or more aerobic stages.   A small quantity of
organic  nitrogen, of which a part is soluble and readily convertible to
ammonium  through  microbial  action, is also usually present.  Insoluble
organic nitrogen associated with the particulate matter is also convert-
ible to  ammonium,  although  somewhat  more slowly.  When wastewater is
applied  to  soil, a variety of reactions are initiated, some biological
and  some nonbiological.  Of the biological reactions, nitrification  and
denitrification  are very important.  Nitrification  is important because
it  converts  a  form of nitrogen not readily subject to leaching to  one
that moves readily with percolating water.  Denitrification  is important
because  it  is  the  principal   process  by  means  of which nitrogen as
nitrite  or  nitrate  is lost from the soil system through conversion to
gases that may escape to the atmosphere.
                                  A-l

-------
          A.2.1.1  Nitrifying Bacteria


The  conversion  of ammonium to nitrate in soil  and water systems is due
primarily to activities of a few genera of autotrophic bacteria of which
Nitrosomonas and Nitrobacter are the most important.  These bacteria are
normal  soil  inhabitants and are usually present  in sufficient numbers to
convert added ammonium to nitrate rapidly and completely, if environmen-
tal conditions  are suitable.  Schloesing and Muntz first discovered the
biological  nature  of  the  nitrification  process  by  pouring  sewage
containing  ammonium onto columns of soil mixed  with limestone and found
that,  after  the elapse of a few days, nitrate  appeared in the effluent
at the bottom [1].
The  nitrifying  bacteria  are obligate aerobes  that derive their energy
from  the  biochemical   reactions  involved  in  oxidation of ammonium or
nitrite.  The principal  reactions may be written as follows:


                 NH* + 3/2 U2	^N0~ + H20 + 2 H+            (A-l)
                  N0~ + 1/2 0,,	-N0~                          (A-2)
The first  reaction  is carried out by bacteria of the genera Nitrosomo-.
nas, Nitrosococcus, Nitrosocystis,  and Nitrospira; the second is  accom-
plished by Nitrobacter  and related  species.   These bacteria require no
organic  matter as a source of energy.  A number of heterotrophic nitri-
fiers are  known  to occur, but their activity appears to be slight com-
pared to  that  of  the autotrophic forms [2].  Although nitrifying bac-
teria are  abundant  in  most soils,  populations may be initially low in
subsoils  or  in coarse-textured  soils that are prone to be dry much of
the  time.   In such soils, several  weeks may  be required for nitrifiers
to attain maximum numbers after application of wastewater is begun.
          A.2.1.2  Rates of Nitrification
Rate  constants  based  on the assumption of steady state conditions and
first  order kinetics have been published [3];  but these may have little
value  in relation to field situations where soil  properties, population
size, and other variables are subject to considerable fluctuation.   Rate
constants  that have been normalized to take into  consideration the size
of  the  nitrifying  population  are  more  comparable  from one soil  to
another,  but  are impractical  for application  to  field conditions  owing
to  the  difficulty of obtaining reliable counts.   Under favorable  mois-
ture and  temperature  conditions, measured values of ammonium converted
                                  A-2

-------
to  nitrate  ranging from 5 to 50 ppm nitrogen per day (soil  basis)  have
been  reported  [4,  5].   For purposes of calculation,  if one assumes  a
depth  of  only  4  in.  (10 cm) of soil  implicated in the nitrification
process  owing to ammonium adsorption near the surface,  it can be deter-
mined that  these  rates  are equivalent to 6 to 60 lb/acre'd (6.7 to 67
kg/ha*d) of nitrogen.  The lower rate would be sufficient to  nitrify the
ammonium  in  1.2 an. (3 cm) of wastewater per day containing 20 mg/L of
NH|;     and  at the upper end of the range, 12 in./d (30 cm/d)  could be
accommodated.  Even higher nitrification rates in soil columns have  been
reported [6,  7].   These  calculations are consistent with observations
that complete conversion of input nitrogen to the nitrate form occurs if
wastewater  application  periods are short enough to prevent  development
of anaerobic conditions [b, 9].
The  tendency of soils to adsorb ammonium near the surface may result in
temporary  buildup  of  ammonium in a shallow layer,  particularly if the
nitrifying population has not been increased by previous inputs of ammo-
nium.  This  situation  results  subsequently  in a wave of nitrate at a
high concentration following the increase in the number of nitrifiers to
a  level that permits rapid oxidation of the adsorbed ammonium.  This is
illustrated  in  Figure A-l,  where  wastewater  containing  42 mg/L  of
NHj-N  applied  to  a  soil  column  at the rate of 3 in./wk (7.5 cm/wk)
produced an effluent containing up to 107 mg/L of N03-N [10].  Following
the period of population buildup (about 5 weeks in this soil),  ammonium
was nitrified as rapidly as it was applied,   and nitrate concentrations
fell to the input level.  A recurring nitrate wave phenomenon is readily
observed in  systems  of alternate flooding and drying [11].  Here it is
due to the intermittent nature of nitrification, which occurs only during
the drying cycle when oxygen is available.


The rate of nitrification is much more likely to be inhibited by lack of
oxygen  or  low  temperature  than by an inadequate population of nitri-
fiers.  The usual situation in soils is that nitrite rarely accumulates,
indicating that the activities of  Nitrdbacter proceed more rapidly than
does  the oxidation of ammonium.  Nitrite oxidation is inhibited by free
ammonia  in liquid systems, particularly when the pri is alkaline; but in
soils,  adsorption  of ammonium prevents this inhibition from becoming a
practical consideration in most circumstances.
Prolonged  application  of  high ammonia content wastes,  such as sludge,
may  result  in loading that exceeds the ammonium adsorption capacity  in
which  case  free  ammonia may reach concentrations sufficiently high  to
retard nitrite oxidation.
                                  A-3

-------
                              FIGURE A-l

         NITRATE IN EFFLUENT FROM A COLUMN OF SALADO SUBSOIL
         RECEIVINGS IN./WK OF WASTEWATER CONTAINING 42 mg/L
                NHJ-N, SHOWING HIGH-NITRATE WAVE [10]
    ioor
     80 -
       1  in./wk . 2.54 ci/wk
                                 WEEKS
          A.2.1.3  Effects of Soil  Properties on Nitrification


               A.2.1.3.1  Aeration


The  theoretical oxygen requirement in nitrification is for about 4.6 mg
oxygen  per  milligram of ammonium-N.   Although the nitrifiers are obli-
gate aerobes,  they  will  continue to function at oxygen concentrations
well below that of the atmosphere [12, 13].


The rate at which oxygen diffuses to the sites where nitrifying bacteria
are located in relation to the rate of oxygen utilization is of critical
importance.   Studies  in wastewater treatment systems indicate that the
minimum level of dissolved oxygen that will permit ammonium oxidation is
around  0.5  mg/L  [14].   In  soils,   it  is  impossible to measure the
dissolved  oxygen  in  the  microsites inhabited by bacteria, and in any
                                  A-4

-------
event  the  situation is complicated by the presence of large numbers of
heterotrophes which may use a greater proportion of the available oxygen
than  do  the  nitrifiers,  if  oxidizable  carbon  is available.  Thus,
anaerobic  conditions  may  readily  develop  in  the  smaller  pores of
unsaturated soils.  Lance et al. found that both diffusion and mass flow
of  oxygen  were  important  as  transport mechanisms between periods of
intermittent flooding in rapid infiltration [6].  Continuous application
of  wastewater  to soils stops nitrification below the immediate surface
by  filling  soil pores and preventing diffusion of oxygen downward.   In
overland flow systems, nitrification can proceed as a result of aeration
of surface water as it moves over the land via sheet flow [15].
Carbon dioxide is required by nitrifying bacteria as a source of carbon,
but since wastewaters usually contain considerably more bicarbonate than
ammonium,  there is little likelihood that nitrification is ever limited
by lack of  CCL  in land application.


               A.2.1.3.2  Temperature
Like all biological processes, nitrification is affected by temperature.
There  is evidence that nitrifiers can adapt to the temperature of their
environment  to  some extent [16], but the optimum usually falls between
75  and  95°F  (24 and 35°C).  Minimum temperatures as low as 36°F (2°C)
have  been  reported  [5,  17].   As  a  rule  of thumb, the activity  of
nitrifiers  increases  by  a  factor  of 2 for every la°F (10°C) rise  in
temperature.   Obviously, nitrification is stopped altogether when soils
are frozen.
               A.2.1.3.3  pH
The  optimum pri for nitrification is in the neutral-to-slightly-alkaline
range corresponding closely to the ph of most wastewater.   However,  when
wastewater  is applied to soil, the controlling factor is  usually the ph
of  the  soil   because  of  the  much  higher  buffer  capacity of soils
containing any appreciable amount of clay and organic matter.   The pH of
very  coarse  textured  soils  may  be  altered  somewhat  by addition of
wastewater,  particularly  with  high-rate  applications.   Nitrification
falls  off  sharply  in  acid  soils,  with  a  limiting  value  in  the
neighborhood of pH 4.5 [4].
Nitrification  is  an  acid-forming  process, with the liberation of two
protons  for each ammonium ion oxidized; out the presence of bicarbonate
and  other  buffering  substances in wastewater is usually sufficient to
neutralize the acid as it is formed [18].   With prolonged application of
wastewater,  even  strong  acidic  soils may be made neutral  or alkaline
[19], indicating that acid produced during nitrification does not play a
dominant role.
                                   A-5

-------
     A.2.2  Denitrification


          A.2.2.1  Microorganisms


The important bacteria in denitrification are heterotrophes belonging  to
the  genera  Hseudomonas, Bacillus.  Micrococcus.  and Achromobacter.  une
of  the  autotrophic  sulfur-oxidizing  bacteria,  Thiobacillus  dem'trifi-
cans, may  also play a significant role in denitrification  where  reduced
forms of sulfur are present.   The denitrifiers are facultative anaerobes
that  preferentially use gaseous  oxygen,  but can  use nitrite and  nitrate
as  electron  acceptors in place  of  oxygen when concentrations of oxygen
become very low.  Denitrifying bacteria,  like the nitrifiers,  are common
soil  organisms  of  widespread distribution.  Focht and  Joseph reported
very  little  correlation  between  denitrification rates and  numbers  of
denitrifying bacteria in soils, indicating that factors other  than popu-
lation size are likely to be  rate-limiting [20].


          A.2.2.2  Energy Sources


The denitrification reaction  may  be  written

               C6H1206 + 4 NO^	^6  C02 + 6 H20 + 2 N2         (A-3)


where  glucose  is  used  as  an example of an organic energy source.   In
this  example,  3.2  g  of glucose is required for each gram of nitrogen
denitrified.  The decomposable organic  matter  required for  denitrifi-
cation may be  present in the soil ,  may be carried in the wastewater,  or
may be produced by plants growing on the soil. For municipal wastewaters
that are applied after having been stabilized to  the degree that  most  of
the BOD has been removed, the organic matter status of the  soil to which
the water is applied  is likely to be  more  important  than that of the
wastewater  itself  for slow  rate applications.  Cannery  wastewater  with
its  high  BOD is an exception, as are  certain other types  of  industrial
wastewater.  The typical distribution of organic  matter in  soils  is  such
that  the  high  concentrations occur at or near  the surface and  decline
progressively  with depth. Moreover, the availability of organic matter
near  the soil surface as a source of energy for  microorganisms is often
greater than that at lower depths.  Gilmour et al. showed that a  flooded
surface  soil  containing  O.yi%   total carbon denitrified  added  nitrate
readily  without  organic  amendments,   out the subsoil containing 0.48%
total  organic  carbon  tailed to denitrify unless an available  organic
substrate  was  supplied  [21].  This means that  the zone of most active
denitrification  is  likely  to be near the soil  surface  in spite of its
proximity  to  the  atmosphere.   This   has  been  demonstrated in field
experiments  by  Rolston et al. who  observed maximum rates  of  production
of  NLO  and   N-   within the top 4 in.  (1U cm)  [22]. Nitrous oxide  is
                                  A-6

-------
an  intermediate  in denitrification and may be evolved from soil  before
it has an opportunity for further reduction to   N£  , particularly when
it  is  produced  near the surface.  McGarity and Myers observed a close
correlation' between  denitrifying  activity  and  total  carbon in some
soils, whereas in others there was little or no correlation with organic
matter  parameters  [23].  They suggested that this was due to localized
accumulation  of  small  quantities  of  energy-rich  available  organic
matter.   With  continued  input  of  wastewater, any such accumulations
would disappear.


Stanford  et  al.  found  a highly significant correlation between total
soil  carbon  and denitrification rate constants for a group of 30 soils
of  diverse  properties.   A  still better correlation was obtained with
extractable  glucose  carbon  [24].  Still riot answered, however,  is the
question of whether such rate constants based on the assumption of first
order  kinetics  would hold up over longer periods than the 10 days used
for  their determination.  Since rate constants are related to available
carbon, it is likely that they would decrease over time.


Elemental  sulfur  or  sulfides can also be used as an energy source for
denitrification,  as  has  been shown by Mann et al. [25].  Sulfides may
play  a  role in denitrification in marshland, or where anaerobic  sludge
is disposed to land.
In  application  of  high  BOL) wastewater, such as cannery wastes,  rapid
denitrification is very probable.  Law et al. reported 83 to 90% removal
of total nitrogen from overland flow treatment of cannery wastes [26].
          A.2.2.3  Aeration
The  threshold  oxygen  concentration which inhibits denitrification has
been  shown by Skerman and MacRae to be very low, in the vicinity of 0.2
mg/L  [27,  28].   Temporally  or  spatially  restricted anaerobism is a
feature  of  virtually all soils.  Temporary saturation may occur during
wastewater application, with exclusion of oxygen from the soil  pores,  or
oxygen  deficiency  may  develop  in  an unsaturated soil if the rate  of
consumption  exceeds the rate of replenishment.  The latter circumstance
is  especially  likely in the smaller soil  pores.  Thus, denitrification
may  take  place  in  a  soil  considered to be well aerated.  Prolonged
exclusion  of  oxygen  from  the soil, as in continuous flooding, causes
denitrification to cease from lack of nitrate, unless this is present  in
the input water.  Lance et al.  reported that, in columns of a loamy sand
soil,  both  mass flow and diffusion were important mechanisms  of oxygen
transport  during  intermittent  flooding  with  secondary effluent [6].
They  noted  that  enough  oxygen entered the soil  during a 5 day drying
period  to  oxidize  all the ammonium applied during 6 days of  high-rate
                                   A-7

-------
application of wastewater containing 20 mg/L of  NHj-N.   Application  of
ammonium  in  excess  of  that which could be oxidized during the drying
period  resulted  in  an  increase of   NH^[   in  the  reclaimed  water.
Klausner  and Kardos reported little effect of secondary sewage effluent
on  oxygen  diffusion rates  in  silt loam and clay loam soils over  the
application range of 0 to 2 in./wk (0 to 5 cm/wk) [29].


In  overland  flow, a sharp gradient in oxygen concentration can develop
between  the  thin layer of water in contact with the atmosphere and the
underlying soil where an anaerobic zone may develop just below the soil-
water interface.   Nitrates  formed  in  the  aerated  flowing water can
diffuse into the reducing zone of soil and undergo denitrification [15].
The  development  of  this  reducing  zone is favored by the high BUD of
wastewaters  and  the relatively impermeable soils to which the overland
flow system of treatment is adapted.
          A.2.2.4  Temperature


The  optimum  temperature for denitrification in soils is very high, 140
to  150°F  (60  to 65°C), but Stensel et al.  reported little temperature
effect  in the 68 to 86°F (20 to 30°C) range  [30].  Of greater practical
importance  is  the minimum temperature.  Bremner and Shaw observed very
slow  denitrification at 36 and 41°F (2 and 5°C), but the rate increased
very rapidly up to 77°F (25°C) [31].
          A.2.2.5 pH


Denitrification  is  very  slow  in  acid soils, increasing rapidly with
increasing  pH  up  to  the neutral-to-slightly-alkaline range [32, 33].
Denitrification affects soil pH according to the reaction


              NO^ + organic matter —^2 + H20 + C02 + OH"       (A-4)


and  has  the  effect  of  neutralizing  a  part of the acid produced in
nitrification.    The   relative   balance  between   nitrification  and
denitrification  will  therefore have an influence on changes in soil pH
resulting  from  wastewater application,   although other factors are of
greater importance in regulating pH, as has been indicated previously.


          A.2.2.6  Nitrate Concentration


The denitrification rate is independent of nitrate concentration over a
fairly  wide  range   [32,  34].     Recently,  Volz  et  al.  reported
                                   A-8

-------
denitrification to be a zero order reaction, but with the possibility  of
some  dependence  on  nitrate  concentration  at very low nitrate levels
[35].   Over  the range of nitrate concentrations that commonly occur  in
wastewater, there is little effect on denitrification rates.
          A.2.2.7  Effects of Living Plants


The   presence   of   living   plants   has   been  shown  to  stimulate
denitrification  [36,  37,  3b].   Woldendorp  attributed  this  to  two
effects:   (1)  low oxygen concentrations in the rhizosphere produced by
respiration of roots and microorganisms, and (2) root excretions serving
as  a  source  of decomposable organic matter [36],  Similar conclusions
were reached by Stefanson,  who reported that in the presence of plants,
N2  was evolved preferentially,  while in their absence,  N£0  accounted
for  most  of the nitrogen loss  [37].    Woldendorp  also  suggests  the
possibility of  stimulation of  denitrification by  specific amino acids
secreted by plant roots [38].  The role of living plants in the denitri-
fication process is  particularly  important in  slow rate  and overland
flow systems.
A.3  Nitrogen Removal from the Soil System


     A.3.1  Crop Uptake


A  major  advantage of applying wastewater to land is the possibility of
recycling   part   of   the  plant  nutrient   content.   The  important
consideration   from   the   standpoint   of  nitrogen  content  is  the
relationship  between  the  crop requirement and the quantity applied in
the  wastewater.   It  should be recognized that a crop does not utilize
all of the mineralized nitrogen in the root zone.  The fraction of total
nitrate  in  the soil that is assimilated by the roots of growing plants
varies  tremendously,  depending  on  the nature of the plant, depth and
distribution  of  rooting,  nitrogen loading rate, rate of moisture flux
through the root zone, and other factors; but in general, the efficiency
of  uptake  is  not  high.  Grasses, particularly perennials, tend to be
somewhat more efficient than row crops.  It is obviously advantageous to
have  the  crop growing actively during all or most of the year in order
to  maximize  nitrogen  removal  in wastewater application, but climatic
restraints  make  this  impossible  in many locations.  Terman and Brown
[39] calculated by means of a regression procedure that average nitrogen
recovery  at all rates by Bermuda grass in the experiments of burton and
Jackson [40] was 59%.
The  most  accurate  estimates of nitrogen uptake efficiencies are those
obtained  by  use  of  isotopically  labelled input nitrogen, but few of
these  are available.   Apparent  uptake  values  are  often computed by
dividing the  quantity of  N  found in the crop by the quantity applied.
Where  the  amount of indigenous soil nitrogen is large, the discrepancy
                                   A-9

-------
between  actual  and  apparent uptake may be enormous.   Some comparisons
for  corn,  where  actual   N   uptake  was  determined   by  the isotope
procedure,  and apparent uptake by the conventional  procedure, are given
in Table A-l [41].

                              TABLE A-l

         NITROGEN UPTAKE EFFICIENCIES OF CORN  IN  RELATION TO
            QUANTITIES OF NITROGEN AND WATER APPLIED [41]
                               Percent

                              Irrigation water applied
                          7.9 in.       23.6 in.       39.4 in.
              N applied,  	 	
               Ib/acre   Actual  Apparent Actual Apparent Actual Apparent
80
160 .
320
57.1
54.3
42.3
173
122
68.6
55.4
63.2
43.8
182
139
75.5
55.7
64.7
48.0
172
123
78.6
              1  Ib/acre =1.12 kg/ha
              1  in. = 2.54 cm


Sopper  and  Kardos  in Pennsylvania  computed apparent removal efficiency
values  of  242 and  334%  of  total  applied nitrogen by two varieties of
corn silage receiving  1 in./wk (2.5  cm/wk)  of wastewater during a single
year  [42].   At  2   in./wk  (5   crn/wk)   the nitrogen removal efficiency
dropped  to 145%.  Over a 6 year  period,  Reed canary grass removed 97.5%
of  the  nitrogen  applied  in 536   in.   (13.6  m)  of wastewater.  In a
hardwood  ,forest,  the nitrogen removal  efficiency at 2 in./wk (5 cm/wk)
was only 39%.   It is clear  that the  apparent removal  values in excess of
100%  include   a  great deal  of nitrogen resulting from decomposition of
soil  organic   matter   and  could  not be  maintained over a long period of
time.   Much lower values for  nitrogen recovery by crop uptake have been
reported by McKim et al.  [43]  and by Karlen et al. [44].
 Total   quantities  of nitrogen removed by harvested crops generally  fall
 in  the  range 50 to 400 lb/acre-yr (56 to 450 kg/ha-yr), depending on  the
 nature   of  the  crop, fertility of the soil, and a number of management
 parameters  [45].   These  amounts  may  account for a major part of  the
 input   nitrogen  in  slow  rate  and  overland  flow systems, and in  the
 former,   application  rates  are  primarily  limited  by  plant  uptake.
 However,   plant  uptake  is  of  relatively  little consequence in rapid
 infiltration systems where input levels as high as 15 tons/acre-yr (33.6
 Mg/ha-yr)  of nitrogen have been reported [a].


     A. 3. 2  Volatilization of Ammonia
The   equilibrium  between   NHj  and  NHa  is regulated by pH,  and   the
proportion   of free   NHa   is sma" 1 at the pH value of most wastewater.
                                  A-10

-------
Application of water through sprinkler systems increases evaporation  and
with  it the quantity of ammonia volatilized.   Scott states that the  net
loss  of water during sprinkler irrigation may vary from as low as 5% to
as  much  as  40%  of the water applied [46].   Henderson et al. measured
ammonia  losses  as  a function of pH of fertilizer solutions applied by
sprinkler  irrigation  and  found that, in general, these were less than
10%  between  pH  7  and 8, but the curve increased sharply above pH  7.8
[47].  Their data would include evaporative losses between the sprinkler
head and the soil surface.
With  any  type  of wastewater application, ammonia losses from the  soil
surface may occur during drying.  The magnitude of such losses is highly
variable,  depending  on  rate  of  application,  extent of drying,  clay
content  of  the  soil, pH of the surface soil, temperature, and type  of
plant cover, if any [48, 49, 50].  The coarse-textured soils favored for
wastewater  application  are  prone to ammonia loss because of their low
clay  content and tendency to dry quickly, although because of their low
retention  capacity  the  proportion  of total ammonia retained near the
surface  is  unlikely  to  be large.  In a greenhouse study Mills et al.
reported  that at pH values above 7.2 at least half the nitrogen applied
to  a fine sandy loam soil was volatilized as ammonia, most of it within
2  days  of  application  [49].   In a laboratory study, Ryan and Keeney
measured  ammonia  volatilized  from  surface-applied  wastewater sludge
containing  950 mg/L of   NH^-N   and obtained values ranging from 11  to
60% of the applied   NH|-N,   depending  on  the  nature of the soil and
loading rate  [51].   Losses  decreased  as  clay  content  of  the  soil
increased,  but  were  directly  related  to the loading rate.  Repeated
applications  of sludge produced greater percentage losses than a single
appli cation.
     A.3.3  Denitrification


          A.3.3.1 Slow Rate Process
The  slow rate process, usually on land which is vegetated at least part
of  the year, is basically an irrigation procedure.   In arid regions the
wastewater  is  used  to meet the evapotranspiration requirements of the
growing  plants, and in humid regions the quantity of wastewater applied
is  limited to levels which do not greatly exceed plant requirements for
water.   The  soil is thus maintained primarily in an aerobic condition,
and   nitrification   is   the   dominant   process.   Nevertheless,  in
agricultural practice, carefully controlled nitrogen balance experiments
usually  reveal   an  unaccounted-for  deficit  which  is  attributed  to
denitrification  [52].  The magnitude of this deficit typically falls in
the  range of 15 to 25% of the applied nitrogen.  A balance sheet from a
field  experiment is presented in Table A-2 [41].  Isotopically labelled
nitrogen  fertilizer  was  used  which  made  it possible to distinguish
                                   A-11

-------
between  the  applied  nitrogen  and  that present in soil or added  from
ctner  sources.   The  losses  over  a  3  year period were a remarkably
constant  fraction  of  tfte  input nitrogen, and consistent in magnitude
witfl ocner reported values [52].
                                TABLE A-2

       THREE YEAR BALANCE SHEET FOR ISOTOPICALLY LABELLED NITROGEN
       FERTILIZER APPLIED TO CORN PLOTS ON HANFORD SANDY LOAM [41]
       Total N adaed.   Removed in grain,  Remaining in soil,  Unaccounted for, Loss,
          Tb/acre         Ib/acre         Ib/acre         Ib/acre       %



1
'
300
600
SOO
200
500
135
274
312
317
321
118
196
384
539
930
47
129
204
294
248
16
22
23
25
17
       1  Ib/acre - 1.12 kg/ha
In  wastewater  application,  the  fraction  of  input nitrogen which  is
denitrified is strongly dependent on available carbon in the soil.  This
is  illustrated  in Figure A-2 which shows data from a column of Panoche
sandy learn receiving 3 in./wk (7.5 cm/wk) of wastewater at two different
NHl-N   levels  over  a  6  month  period.  The chloride curve shows the
behavior  of a nonreactive ion, with no holdup in the soil.  At the 21.4
mg/L  NH|-N level, there was complete removal cf the first 22% of  input,
followed  by several months of nearly complete removal.  Over the  entire
period  there  was  16%  recovery,  or  84%  removal  of input nitrogen.
However, at the 61 mg/L   NHt-N   level,  once  the  supply of available
carbon  was  exhausted,  there was very little denitrification.  Overall
recovery  in the latter case was 83%, corresponding to only 17% removal.
It should be possible to adjust the loading rate for most soils so as  to
maximize   denitrification  in  cases  where  nitrogen  removal  is  the
principal consideration.


Agricultural  wastes,  such as straw residues and manures, are effective
in  stimulating denitrifieation, but these pose problems of handling and
availability  at  land  treatment sites.  Olson et al. applied manure  to
Plainfield  sand  at rates varying from 10 to 27U tons/acre (22.4  to 605
Mg/ha) [53],  Under aerobic conditions, nitrate accumulated to 25  to 180
mg/L,  but  when  the  soil  was maintained in a saturated condition,  as
might  be  done  by  ponding during wastewater application, virtually  no
nitrates  were  found.   Meek  et  al. observed that redox potentials  in
                                   A-12

-------
calcareous  Holtville clay receiving IbO tons/acre (4U3 Mg/ha) of manure
in  each  of  two  successive  years  did not fall below 400 mV with the
normal  irrigation  schedule, whereas the potential dropped to zero when
the  number of irrigations was doubled [54].  These authors suggest that
it  is  possible  to  adjust  manure  application  rates  and irrigation
schedules  for  fine-textured  soils to achieve maximum denitrification.
The principle is applicable to other kinds of wastes as well.
                              FIGURE A-2

           EFFECT ON INPUT NH4-N CONCENTRATION ON N REMOVAL
            FROM WASTEWATER APPLIED TO PANOCHE SANDY LOAM
              AT THE RATE OF 3 IN./WK FOR 6 MONTHS [41]
    100 i-
                        (INPUT OF 61mg/L NHi-N)
                       NITRATE.
                        (INPUT OF 21mg/L NH^-N)
    20 -
                            40          60

                          INPUT, % OF TOTAL
      1  in./wk = 2.54 cra/wk
                                   A-13

-------
          A.3.3.2  Rapid Infiltration
In  the intermittent application ofewastewater to soil,  it can be safely
assumed  that  all of the input ammonium not volatilized will  eventually
be  nitrified if the adsorption capacity of the soil  is  not exceeded and
if  the  periods  of application are  interspersed with drying  periods of
sufficient length and frequency to replenish soil oxygen.  Bouwer et al.
reported  essentially  quantitative conversion of ammonium to  nitrate in
rapid  infiltration  systems  having   2 to 3 days of  flooding  alternated
with  5  days  of  drying [8],  Robeck et al.  obtained about 74% ammonia
removal  in  Ottawa  sand with shorter and more frequent applications of
wastewater at a rate of 8 in./d (20 cm/d) containing  nitrogen  equivalent
to 50 lb/acre-d (55 kg/ha-d) [9J.   This removal  was attributed primarily
to nitrification.  Thus, in rapid infiltration systems,  nitrification is
the  dominant  process  unless  specific  steps  are   taken  to  promote
denitrification.
In  rapid  infiltration experiments with soil  columns,  Lance and Whisler
found  no  net removal of nitrogen with 2 days of flooding followed by 5
days  of drying, but net removal  was 30% with  longer cycles involving  9
to 23 days of flooding and 5 days of drying [7].   Lance et al.  developed
two  successful   methods  for  maximizing  denitrification  in  high rate
applications  which achieved 75 to bO% removal of nitrogen [55].  On the
basis of their finding that the percentage of  nitrogen  removal  increased
exponentially   as   the   infiltration  rate   decreased,   they  reduced
infiltration  rates  by  soil compaction to a  level  that allowed nitrate
formed  during  the  dry  period to mix with the  wastewater subsequently
applied in order to provide a favorable ratio  of  carbon to nitrate.  The
second  method involved recycling water of high nitrate content that had
passed  through  the  column as a nitrate peak.  This was  mixed with two
parts of secondary effluent and recycled throughout the remainder of the
flooding period,  both methods encounter practical  difficulties in field
application.   Adjusting depth of ponding, compacting the  surface of the
soil,  and  altering  the solids content of applied wastewater  have been
suggested  as means of changing infiltration rates [55].  Recycling high
nitrate  water  in  the field would require interceptor drains  below the
water  table,  the effluent from which would be pumped  to  a holding pond
and mixed with wastewater prior to reapplication.


An  alternative  method of increasing nitrate  removal by denitrification
is  to add an energy source.  Methanol has been used for this purpose in
reducing  the  nitrate  content of drainage water [56].  The theoretical
methanol  requirement  in this process for wastewater containing 20 mg/L
of  NO§-N  would be 45.7 mg/L,  or the equivalent of 1.6 gal of methanol
per acre-inch (5.9 L/ha-cm) of water, assuming that all the methanol  is
used  by  denitrifying bacteria.   Experiments  with drainage water showed
that up to 90% removal of nitrate could be achieved with water  initially
containing  20  mg/L  of  NO^-N  by  addition  of  70 mg/L of methanol, or
                                  A-14

-------
about  150%  of  the  theoretical  requirement [56].   It is unlikely  that
methanol added to municipal wastewater and then applied to soil  would be
used  as  efficiently,  owing  to  the  presence  of  large  numbers  of
heterotrophic  microorganisms  in  addition  to  the  denitrifiers.    An
inherent  difficulty  is  that  the period of aerobic microbial  activity
required  for nitrification of input ammonium permits rapid depletion of
available  carbon,  leaving little for use of denitrifiers when  the  soil
is again flooded.


          A.3.3.3  Overland Flow
In  overland  flow treatment, a thin film of wastewater passing over the
surface  of  soils of relatively low permeability serves as a barrier to
oxygen movement below the soil  surface.  This permits the development of
anaerobic  conditions  in  the  soil  near the soil-water interface with
attendant  denitrification.   Other  aspects  of  this type of treatment
which favor denitrification are the close proximity  of an oxidizing zone
in  the  flowing  water,  and  the high BOD of wastewaters to which this
method  is  applicable.   This  allows  nitrification in the water film,
followed  by  movement  of nitrate into the reducing zone below the soil
surface  where  energy  for denitrifying bacteria is supplied by soluble
organic  matter  from  the  wastewater.   Quantitative  data showing the
relative  importance  of  denitrification  in relation to other nitrogen
removal  mechanisms  such as plant uptake and ammonia volatilization are
lacking,  but  reported  high  removal efficiencies  of 75 to 90% suggest
that denitrification is the dominant process [57, bb, 59],
     A.3.4  Leaching


Nitrogen  applied  in  excess  of crop removal  is potentially subject to
leaching,  but  in  practice, losses by volatilization of ammonia and by
denitrification  diminish the actual quantities of nitrogen leached.   In
arid   regions,   some   leaching  is  essential   to  prevent  excessive
accumulations  of  salt.   In  most situations, some movement of nitrate
from the root zone to the groundwater is unavoidable.
In  land  treatment  systems, it is desirable to have an estimate of the
amount  of  nitrate  leached,  but  reliable estimates are difficult and
expensive  to  obtain.   In  considering  nitrate  as a pollutant, it is
important   to  bear  in  mind  that  total   mass  flow  is  of  greater
significance  than concentration per se.  In applications on cropland at
rates  not  greatly  in  excess  of  the consumptive use requirement for
water,  fairly  high  concentrations of nitrate in the subsoil  would not
represent  a high pollution hazard because of the low leaching  fraction.
On  the  other  hand,  in  high  rate  application with a large leaching
fraction,  a much greater mass of nitrogen may move into an aquifer even
                                  A-15

-------
though  the nitrate concentration is relatively low.  In crop irrigation
systems, the quantity of nitrogen that is potentially leachable (nitrate
form)  increases  sharply  above  the  input  level  required to achieve
maximum  crop production, as is illustrated in Figure A-3.   The applied
nitrogen cannot be balanced by the leachable nitrogen plus crop nitrogen
because   incorporation   of  nitrogen  into  soil  organic  matter  and
denitrification amounts in Figure A-3 are unknown.
                               FIGURE A-3

           YIELD, CROP UPTAKE OF N, AND POTENTIALLY LEACHABLE
           NITRATE IN RELATION TO FERTILIZER APPLICATION RATE
                ON CORN GROWN ON HANFORD SANDY LOAM [41]
           500 I-
          400 -
          300 -
                           LEACHABLE N IN SOIL
          200 -
           100 -
              ID
              h_
              O


           3  >
           2  _•
             0        100       200       300

                             N  APPLIED,Ib/acre

             1 lb/acre=1.12  kg/ha
             1 ton/4 ere = 2.24 Kg/ha
400
500
Monitoring  nitrate  flux  in  a field situation is not a simple matter.
Porous  ceramic probes, sometimes referred to as suction lysimeters, are
often  used  to  obtain  samples  of soil solution at various depths and
locations without disturbing the soil after the initial installation.  A
rather  dense  network  of  such  probes  is required to obtain reliable
estimates  of  soil nitrate concentrations.  Even in soils considered to
be  uniform, these concentrations are subject to wide variations both in
time  and  in  space.   This  is  illustrated  by the data of Table A-3,
obtained  from  probes  located in a corn field on Yolo fine sandy loam.
It  will  be noted that individual samples vary by an order of magnitude
or  more  from  replicate  samples  in  several  instances, and standard
deviations from the mean ranged from 32 to 114% of the mean.
                                   A-16

-------
                                 TABLE A-3

             NITRATE-N CONCENTRATIONS IN SOIL  SOLUTION SAMPLES
          OBTAINED  BY MEANS OF SUCTION PROBES AT  FOUR DEPTHS ON
         TWO DATES  IN A CORN FIELD ON YOLO FINE SANDY LOAM [41]


                                     No. of samples and depth
                              4 at 4 ft 4 at 6 ft  8 at 8 ft  8 at 10 ft


             Jul 28, 1975

             Mean NO^-N, mg/L      31.9      25.8    30.3      32.0

             Range, mg/L         15.2-60.0 18.9-35.6  6.8-58.9  7.8-55.4
             Standard deviation,
             % of mean           61       32      58       45

             Aug 28. 1975

             Mean NO;j-N, mg/L      19.5      12.3    26.3      32.4

             Range, mg/L         1.8-50.4  2.3-22.4  1.8-47.2  5.1-58.9
             Standard deviation,
             % of mean          114       67      66       54


             1 ft * 30 cm
It  is clear  that estimations of nitrogen removal  based on a few suction
lysimeter   samples  may  be  in  serious  error.    It  should be further
realized  that  measurements  of  moisture  flux  in unsaturated soils are
subject  to   the   same  kind  of  variation, making calculations of mass
balance  even more hazardous.  This variability  is inherent in sampling
natural  bodies   for virtually any parameter.  The conclusion is that it
is  not  generally practical to attempt to  estimate nitrate removal from
wastewater  in  slow  rate applications by  monitoring composition of the
soil  solution.   In rapid infiltration applications,  where the amount of
water  applied  is  much  greater than consumptive use and where applied
nitrogen  greatly  exceeds  any  soil contribution, measurements made on
samples  from the  zone  of saturated flow obtained by means of suction
cups, wells,  or tile lines are somewhat more reliable.
     A.3.5  Storage  of Nitrogen in Soil


In  a  theoretical   equilibrium  situation  over   the  long  term, where
additions  and  removals of nitrogen are in balance,  the storage capacity
of  the  soil is  of  little consequence from the standpoint of management
practice,  even though the residence time in  the  soil  may be quite long.
In  actual  wastewater application practice,  particularly with slow rate
systems,  the   storage of nitrogen is very important because equilibrium
                                    A-17

-------
is  not quickly attained.  The principal  storage mechanisms are fixation
of  ammonium  by clay minerals and organic matter, retention of ammonium
as an exchangeable cation, and incorporation into soil  organic matter.

          A.3.5.1  Ammonium Fixation
Certain  clays  that  commonly occur in soils,  particularly those of the
vermiculite  group,  have  the  ability to trap ammonium ions within the
crystal  lattice.  Ammonium ions thus fixed do  not exchange readily with
other  cations  and  are  not  accessible  to  nitrifying bacteria [60].
Fixation  of  NH|  by clays is enhanced by wetting and drying cycles but
may  occur  without drying.  The quantities so  fixed depend on the kinds
and  amounts of  clay present.   Quantities of    NHj    fixed  by  three
different  soils  receiving  five consecutive applications of a solution
containing  100 mg/L  of   NH|-N  without intervening drying periods are
shown in  Figure A-4.    The  Aiken  clay,     containing  predominantly
kaolinite,  fixed  no NHt .   The Columbia fine sandy loam,  typical  of
coarse  textured soils tnat might be used for wastewater disposal, fixed
22  ppm  NHt   (soil basis),   equivalent  to  about  275 Ib/acre   (308
kg/ha) of  " nitrogen  in the top 3 ft (1  m) of  soil.   This soil  and the
Sacramento  clay  contain  vermiculite  and  montmorillonite  capable of
NHj  fixation.
                              FIGURE A-4

           CLAY-FIXED NHt  IN THREE SOILS RESULTING FROM FIVE
            APPLICATIONS  OF A SOLUTION CONTAINING 100 mg/L
               NHj-N, WITHOUT INTERVENING DRYING [41]
          40 r
                                  COLUMBIA FINE SANDY LOAM
                          NUMBER OF APPLICATIONS
                                  A-18

-------
Another  mechanism  of    NH|   fixation  involves  reaction  with  soil
organic  matter  to form  stable  complexes.    The amounts fixed depend
strongly  on  pH  and  quantity  of  organic matter present [61].  It is
unlikely  that  this  mechanism   is  of  much  importance  at  the  low
NHj  concentrations  and near-neutral pH of wastewaters normally applied
to  soils  of low organic matter content, but'it may assume considerable
importance in sludge applications where   NHj   concentrations  are   at
least  an order of magnitude higher and where organic matter is supplied
by the sludge.


          A.3.5.2  Exchangeable Ammonium


Like  other  cations  in  wastewater,   NHt   can  be  adsorbed  by  the
negatively charged clay and organic colloids in soil.  Lance discussed a
method of estimating the quantity of   NH^   that might be adsorbed from
a    particular   wastewater  based  on  the  ammonium  adsorption ratio
calculated  from  the  concentrations  of  NH| ,   Ca++   ,   and   Mg++
in  the  water  [62].   In  slow  rate  systems, the ammonium adsorption
capacity  of  soils is usually sufficient to retain the applied ammonium
near  the  surface.   Continuous  flooding in rapid infiltration systems
will  in  time  saturate  the  ammonium  adsorption  capacity and permit
downward   movement   of   ammonium.    Retention  of  ammonium  in  the
exchangeable  form is temporary in any case, since'the adsorbed ammonium
is  nitrified when oxygen  becomes  available;    but exchangeable   NH|
plays a very important role in the nitrification-denitrification sequence
by  holding nitrogen near the soil surface until  the environment becomes
aerobic during drying.


Even  in  sandy  soils  of  low cation exchange capacity the quantity of
exchangeable  ammonium  is  of  consequence.  A profile of  exchangeable
NH|  beneath a sludge drying pond as compared to untreated soil is shown
in Figure A-5.    This  represents  a  situation  where  high  NH|  con-
centrations combined with a low infiltration rate have resulted in domi-
nance of the cation exchange complex by  NHt  .   The total quantity  of
exchangeable  NHt  in this soil to a depth of 6 ft (1.8 m) is 10 530 lb/
acre  (11 800 kg/ha).    The»same  profile also contained  1 250 Ib/acre
(1 400 kg/ha) of  NO^-N .   In a somewhat  different situation,    Lance
cites calculated values of exchangeable  NHt  equivalent  to   1 554 lb/
acre (1 740 kg/ha) for  a wastewater  applied to a soil with an exchange
capacity of only 5 meq/100 g [62].


          A.3.5.3  Incorporation into Organic Matter


Ammonium  may be incorporated into organic matter by the fixation mecha-
nism previously  discussed, through  assimilation by microorganisms, and
by plant uptake.  Net immobilization by microorganisms requires the pre-
sence of decomposable organic matter having a nitrogen content less than
                                   A-19

-------
about 1.2%.  Except for cannery wastes and certain types  of  industrial
wastes, these conditions are not met  for  land treatment systems.   The
presence of mature crop residues on land receiving wastewater may result
in immobilization  of  a  small amount  of nitrogen, though probably not
more than 40 to 60 Ib/acre (45 to 65 kg/ha).
                EXCHANGEABLE NHJ
           BENEATH A SLUDGE PONt
FIGURE A-5

  IN THE PROFILE OF A SANDY SOIL
  AS COMPARED TO AN UNTREATED AREA [41]
          UNTREATED
        1  ft= 0.305 n
                                  A-20

-------
The  most  important  mechanism  of  storage is through plant uptake  and
subsequent conversion of root and other residues into soil  humus.   Large
quantities  of  input nitrogen can be stored in soil  for long periods of
time  in  this  way,  particularly  in  soils  of  initially  low organic
nitrogen  content.   This  is  illustrated  by  the  profiles of organic
nitrogen  shown  in  Figure  A-6  for  a  cropped area near Bakersfield,
California,  where  wastewater  had  been  used  to irrigate  crops  for a
periods  of  36  years  at the time of sampling, compared to  an  adjacent
area  of untreated soil  that had never been cropped or irrigated.   Total
nitrogen  down  to  a  depth  of 5 ft (1.5 m) increased by 7  400 Ib/acre
(8 290 kg/ha)  as a  result of wastewater application,   representing an
average  annual  increment  of  2U5 Ib/acre (230 kg/ha) over  the 3b year
period.
Lesser  quantities  of  nitrogen  would be stored in the organic  form  in
soils  of  initially  higher  organic  nitrogen  content;  and  in   some
instances,  such  as  those reported by Sopper and Kardos where  apparent
crop removals of nitrogen greatly exceeded the quantity applied  with the
wastewater,  net  mineralization  of soil  organic nitrogen will  actually
decrease  the  quantity  stored  [42].    Net immobilization is common  on
soils  of  arid  regions  where  there  has been little previous  input  of
organic  matter.   Net  mineralization   is  more likely in soils  of  more
humid regions where the native level of organic matter is usually higher
because  of  more abundant vegetation.   Soils of arid regions which  have
been  irrigated  for  many  years  would  be unlikely to accumulate  much
additional N during wastewater application.


A.4  Nitrogen Removal  with Various Application Systems


     A.4.1  Slow Rate Systems for Irrigation of Crops


Wastewater used for crop irrigation is  commonly applied by sprinklers  or
ridge-and-furrow  distribution  systems,  with  the  rate of application
geared  to  the  needs  of the crop for water and nutrients.  Nearly all
data   on   efficiency   of  nitrogen  removal   have  been  obtained  at
experimental   sites.    In  an  EPA  survey  of  facilities  using   land
application  of  wastewater,  nitrate concentrations in groundwater  were
reported  at  only ID of 155 locations  using municipal  wastewater and  at
only  '
-------
                               FIGURE A-fa

            EFFECT OF 36 YEARS OF WASTEWATER APPLICATION ON
          ORGANIC N IN A SOIL AT BAKERSFIELD, CALIFORNIA [41]


                               ORGANIC N,X

1
0.04
1
0.08
1 1
O.t2
1 1
0.16
I 1
           51-
            1 ft = 0.305 m
Mineralization   of  organic  nitrogen  in  soils  may  also  contribute
appreciably  to  nitrate  that  eventually reaches groundwater.  This is
illustrated  by  the  data  of  Table  A-4  which  give total  and tagged
nitrogen  in  the  effluent from soil columns treated with wastewater in
which  the  input  water,  applied  at  3  in./wk  (7.5 cm/wk) contained
NHj-N  labelled  with the  15N  isotope.     This  made  it  possible  to
identify the nitrogen in the effluent which was derived from the applied
wastewater.   The  difference  in  percent  recovery of total  and tagged
nitrogen  is due to the contribution of soil  nitrogen, most of which was
converted  from organic forms to nitrate  during the period of treatment.
Thus,  net  removal from the Sal ado fine  sandy loam after application of
137  in.  (34b cm) of wastewater would be calculated at only 6%, whereas
the  true removal was 48%.   Total  N added to this soil in wastewater was
equivalent  to 1 315 Ib/acre (1  473 kg/ha),  and the effluent  contained
                                   A-22

-------
1   236 Ib/acre  (1 3b4 kg/ha) of nitrogen; however,  only 684 Ib (766 kg)
was derived from wastewater, the other 552 Ib (618 kg/ha) of nitrogen in
the effluent being produced by decomposition of soil  organic matter.  In
soils of low organic content, such as the Sal ado subsoil, this factor is
of minor importance, as shown by the close correspondence in the figures
for  total   and  tagged  nitrogen.   At  low application rates, nitrogen
removal  can  be completely masked by mineralization of organic nitrogen
in  the soil, as is illustrated by the Panoche sandy loam.  A comparison
of nitrogen input versus output shows a net gain, or no removal, whereas
in fact 97% of the input nitrogen did not appear in the effluent.

                                TABLE A-4

                   RECOVERY  OF TOTAL AND TAGGED N  IN EFFLUENT
                    FROM THREE  SOILS  RECEIVING 15N-LABELLED
                    WASTEWATER  AT THE  RATE OF 3  IN./WK  [41]
Wastewater
applied
Soil
Sal ado fine
sandy loam
Salado
subsoil
Panoche
sandy loam
in.
48
137
48
137
87
Ib N/acre
459
1 315
459
1 315
429
N recovered
in effluent, %
Total
24
94
20
78
141
Tagged
1.3
52
17
75
2.7
                       1  in. * 2.54 cm
                       1  Ib/acre - 1.12 kg/ha
 If  total  nitrogen  input does not greatly exceed crop requirements for
 nitrogen,  removals  of  35  to  60% can be expected as a result of crop
 uptake.    Depending   on  soil  properties  and  irrigation  schedules,
 denitrification may account for 15 to 7U% of the input nitrogen, or even
 more  at low loading rates.  In agricultural practice where attempts are
 made  to  minimize  denitrification, losses of 15 to 30% are common [64,
 65].   Lienitrification losses with sprinkler irrigation are likely to be
 lower  than  with  furrow application because the soil is less likely to
 reach  the  saturated  condition, but this may be balanced out by higher
 ammonia  loss  in  sprinkler  application.   Ammonia  loss from the soil
 surface  during  periods of drying may be a more important consideration
 than is commonly realized [50].


 Normally,  in  wastewater  application to crops, it is desirable to rely
 primarily on crop uptake as a means of nitrogen removal, and a number of
 years  of  field experience indicates that the procedure is effective in
                                    A-23

-------
both  forest and cropland when rates of application are adjusted to  soil
and  crop  capacity  [42, 66].  The capacity of soil  to receive nitrogen
may  be  greatly  enhanced  by  long-term  storage  in those soils where
substantial buildup of organic nitrogen may occur.  The Werribee farm  in
Australia  is  a case in point [67],  Soil  nitrogen increased from 1 200
to  2 620  ppm after 12 years of irrigation with wastewater.  Even if  it
is  conservatively  assumed  that  the  increase  was  restricted to the
surface  6  in. (15 cm), the additional nitrogen stored is equivalent  to
about 2 500 Ib/acre (2 800 kg/ha) averaging a little over 200 Ib/acre-yr
(225 kg/ha-yr)., which is of the same order-of-magnitude as crop removal.
This  value is almost identical to the previously cited value maintained
over  a  36  year  period  at  Bakersfield,  California.   In the latter
instance,  however,  a  much greater depth of soil was implicated in the
storage.   After  26  years of wastewater application, the Werribee  farm
showed  a  surprising  drop in nitrogen content, the reason for which  is
not  apparent.   Adriano  et al. estimated total nitrogen immobilization
during  20  years  of  cannery  waste application to sand and loamy  sand
soils  to  be  as  much  as  2 700 Ib/acre (3 000 kg/ha), accounting for
approximately  one-third  of  the  total   nitrogen  applied  it>«].   The
quantity  of  nitrogen immobilized in a given situation depends somewhat
on wastewater composition, being greater with wastewater of high BOD and
low  nitrogen content, but it is also affected by climatic variables and
nature  of  the soil.  With constant management, an equilibrium level  of
organic  nitrogen will eventually be attained, but this may require  many
years.


Slow rate land treatment provides sufficient nitrogen removal in several
reported  instances to  produce a soil percolate below 10 mg/L of NOjj-N
[42].   Karlen  et al.  reported reduction of nitrogen  content  from  15
to  7  mg/L  with  an  annual  application  rate  of  79 in. (200 cm)  of
wastewater  containing  26b  Ib/acre  (300  kg/ha)  of  nitrogen on  corn
growing on a loam soil with tile drainage [44].  The maximum weekly  rate
was  5.3  in.  (13.4 cm).   McKim et al. in New Hampshire reported total
removals  of  nitrogen  ranging from 73 to 91% with primary or secondary
effluents  applied  to  grass  at  2 and 4 in./wk (5 and 10 cm/wic) [43].
Total  nitrogen  applications varied from 212 to 426 Ib/acre (238 to 478
kg/ha),  and  the average concentration of nitrogen in the wastewater  of
about  35  mg/L  was  reduced  to 3 to 10 mg/L in the percolate.  In the
well-known  long-term experiments at Pennsylvania State University,  soil
solution  samples  at  the 4 ft (1.2 m) depth in Reed canary grass plots
receiving 2 in./wk of wastewater consistently showed less than 4 mg/L  of
NO^-N.   Application of 2 in./wk to red pine and hardwood plots resulted
in  soil  nitrate concentrations at the 4 ft (1.2 m) depth substantially
in  excess  of  10  mg/L of nitrogen, although with 1 in./wk (2.5 cm/wk)
they  remained  below this value.  Kardos and Sopper conclude that,  with
appropriate management of nitrogen loading rates to maximize crop uptake
ana  with  hydraulic  loadings  adjusted to maximize denitrification,  it
should  be  possible  to  recharge  water  that  meets  drinking quality
standards for nitrogen into the aquifer belowaland treatment site  [19].
                                    A-24

-------
     A.4.2  Rapid Infiltration Systems


Rapid  infiltration  systems  use application rates as high as 360 ft/yr
(110  m/yr)  and  annual  nitrogen  loading up to 36 000 Ib/acre (40 300
kg/ha)  on highly permeable soils.  Although grass is sometimes grown on
the  receiving  areas,  the  quantity of nitrogen removed by the crop is
only  a  small fraction of the total  applied and exerts little influence
on  the quality of the percolating water.  Much of the quantitative data
on  rapid  infiltration  systems  is  derived  from the Flushing Meadows
project  at Phoenix, Arizona.  Lance and Whisler concluded that the only
feasible  mechanism  for  removing  the  large quantities of nitrogen in
high-rate  applications  is denitrification [7].  Bouwer et al. reported
that  overall  nitrogen  removal  during  sequences of long flooding and
drying  periods  was  about 30% [8].   Reducing the infiltration rate 50%
had  the effect of increasing nitrate removal to 80%.  Lance published a
table showing calculated percentages of nitrogen removal ranging between
75 and 80% using different management systems [62]. The systems involved
reduction  of  the infiltration rate or recycling high-nitrate percolate
and  mixing  it  with  secondary effluent prior to reapplication.  These
techniques  for  achieving  high  nitrogen  removal, although promising,
require testing on a field scale before widespread adoption.


In  the  Santee,  California, project, municipal effluent applied to the
alluvium  of  a  shallow  stream  channel undergoes about 10 ft (3 m) of
vertical   percolation   followed   by   considerable  lateral   movement
underground  [69].  Total nitrogen in the renovated water was reduced to
l.b mg/L, compared to about 25 mg/L in the spreading basins.  At Detroit
Lakes  in  Minnesota  where  about  98  ft/yr  (30 m/yr) of effluent was
applied  by  sprinkling  on  a  schedule of 20 hours on and 4 hours off,
input  nitrogen  was  converted  to  nitrate, but little denitrification
occurred and nitrate appeared in the groundwater at concentrations equal
to the influent [70].  In another system with a loading rate of 45 ft/yr
(14  m/yr)  where  2 weeks of wetting was followed by 2 weeks of drying,
70%  removal  of  total  nitrogen  was  achieved  [71].  At Fort Devens,
Massachusetts,  where  rapid  infiltration  of primary effluent has been
used  since  1942,  recent  data  show  that where 91 ft/yr (28 m/yr) of
wastewater  was  applied on a scnedule of 2 days of flooding followed by
14  days  of  drying, nitrate-nitrogen concentrations in the groundwater
were  20  to  40%  of  the average total nitrogen input level of 47 mg/L
[72].
     A.4.3  Overland Flow Systems


Land   application   of   wastewater   on  fine-textured  soils  of  low
permeability  has been made possible by development of the overland flow
treatment  method.   The  relatively  high clay content of such soils is
                                  A-25

-------
advantageous in nitrogen removal  because  of their increased capacity  for
adsorption  of  ammonium and slow diffusion rates of gases  through  them,
thereby  permitting  development   of an anaerobic zone near the surface.
Hoeppel et al.   have  shown  that  concentrations of  NH+  and  NO^   in
surface runoff  are  linearly correlated  with  flowrate,  indicating that
efficiency  of nitrogen removal  depends on time of contact  between  water
and the soil surface [57].
In  this mode of treatment a ground cover is required,  usually  a  species
of  grass that is tolerant of wet conditions,  such as  Reed canary grass.
The  rates  of  application  in  some overland flow systems exceed plant
uptake  by  a  substantial  margin, but plant uptake undoubtedly plays  an
important  role  in  nitrogen   removal.    Carlson  et  al.  reported   a
pronounced  gradient  in the growth of grass between the lower  and upper
ends  of  the  slope in their model, with nitrogen deficiency evident  at
the  lower  end, which shows that much of the inorganic nitrogen  present
was assimilated by the grass, lost to denitrification,  or both  [bb].
In addition to crop uptake, the important processes involved  in  nitrogen
removal   during  overland  flow  may  include  ammonia  volatilization,
adsorption  of ammonium by clays and organic  matter,  immobilization,  and
denitrification.   Insufficient  data  are  available  to  evaluate   the
relative  importance  of  these  processes  under  a   particular  set of
circumstances.   Law  et al. reported the maximum pH  of cannery  waste at
the  Paris,  Texas,  site was 9.3, while the  value in the runoff was  b.l
[26].   At  these  values,  ammonia volatilization could be appreciable.
Ammonium  adsorption  is  probably  involved   in  development of a slope
gradient in nitrogen available to the grass.
The  overland  flow  system  is  ideally  adapted  to the  nitrification-
denitrification sequence,  which requires aerobic and anaerobic  zones  in
close  proximity.   Applied  wastewater  is  aerated  as it contacts the
atmosphere  as  a thin film flowing over the surface, thereby permitting
nitrification  to  occur.   Nitrate  thus formed diffuses  into the  soil,
encountering  reducing  conditions in which denitrification can  proceed.
The  presence of living plants provides a mat of organic debris  and root
excretions  which  can  be used as a substrate by denitrifying bacteria.
Conditions  are  even more favorable for denitrification with wastewater
of   high   BOu,   such  as  cannery   effluents.   Thomas  states  that
denitrification  is  the major mechanism of nitrogen removal  in  overland
flow  systems  [5y].   Another  aspect  of  the  role of plants  is  their
influence   on   the   loss   of   nitrogen  through  the  nitrification-
denitrification processes in the root zone.  Plants capable of surviving
in  wet  environments have a mechanism for translocating oxygen  from the
tops  to  the  roots,  and  may even excrete oxygen from the roots. For
example,  healthy  rice roots grown in flooded soil often  have a reddish
coating  due  to  hydrous  oxides  of  ferric  iron, clearly denoting  an
oxidizing  micro-environment  even though negative, or strongly  reducing
                                  A-26

-------
oxidation-reduction  potentials  exist  in  the  soil   proper.    In  the
immediate  root  zone,  or  rhizosphere,  nitrification may occur,  after
which the nitrate so formed will  diffuse away from the site of  formation
and  be  denitrified.   In  support of this view is the observation that
nitrogen losses occur in rice soils even when ammonia  sources are placed
directly in the reducing zone [73].                                 ;

                    /
The  overland  flow  systems  for  which  data  are  available  show high
nitrogen removal  efficiencies.  Law et al. reported 83 to 90% removal  of
total  nitrogen  from cannery wastes applied on grassland at the rate of
515 lb/acre-yr (578 kg/ha-yr) of nitrogen [26].  In this case where most
of  the input nitrogen was organic and the wastewater  had a high BOD,  it
is  possible that much of the applied nitrogen was incorporated into the
soil  organic  fraction.   Johnson  et  al.  cite  bO%  removal  of total
nitrogen  from  raw sewage at Melbourne, Australia [67].  Hoeppel  et al.
reported  nearly   complete  removal of  NH|   or  NOo   by a  model  over-
land flow  system  using  municipal wastewater on a kaolinitic  clay soil
[57],
     A.4.4.  Wetlands
Very  little information is available on the use of marshes and wetlands
for   wastewater   treatment,  but  a  consideration  of  the  foregoing
discussion  on  the  factors that favor the denitrification process will
make  it evident that such areas have the requisite characteristics of a
nitrogen  sink.   In  marshes  and  swarnps,  the rate of plant growth is
greater  than the rate of decomposition of plant residues as a result of
exclusion  of  oxygen from the surface soil by excess water, since in an
anaerobic  environment  decomposition of plant residues is neither rapid
nor  extensive.   Hence,  soils  formed under these conditions typically
have  high  organic  matter  levels,  some  falling in the peat and muck
categories.   Abundant  organic  matter and an aerobic-anaerobic zone at
the mud-water interface provide excellent conditions for denitrification.
The  potential for  nitrogen removal is  illustrated by consideration of
the area of peat and muck soils in the Sacramento-San Joaquin delta area
of California.    When these soils are drained, aerobic decomposition of
the soil above the water tableisso rapid that subsidence up to 3 in./yr
(7.5 cm/yr) is observed.  The organic nitrogen in the soil is mineralized
and converted to nitrate, which appears in the drained soil at high con-
centrations.  A subsidence of 2 in./yr  (5 cm/yr) represents the release
of nitrogen in the inorganic form of about 4 500 Ib/acre  (5 050 kg/ha).
Notwithstanding this enormous input,   the drainage  waters and  ground-
water  in  the area maintain low  concentrations of nitrate as a  result
of denitrification in the saturated zone.
                                  A-27

-------
Raveh  and  Avnimelech  have reported substantial  enhancement of nitrate
removal by sprinkling or flooding soils in the Hula valley in Israel,  an
area  previously  covered  by  a  lake and marshes [74].   When the water
level  in  a  field  was  raised  to  the surface by flooding, the redox
potential  dropped to about  -100  mV  throughout  the  profile, and the
nitrate concentration in the top layer dropped rapidly from 1 250 to 250
ppm  '(soil basis).    The quantity of nitrate reduced was 1 650  Ib/acre
(1 850 kg/ha) of nitrogen, or about 70% of the amount initially  present
in the top 3 ft  (1 m).   In another experiment, the soil was wetted  by
sprinkling for about 20 hours at a rate lower than the infiltration rate
so  that  the  surface soil  remained unsaturated.   In this case, nitrate
disappearance  from  the  top  3  ft  (1m) was about 980 Ib/acre (1  100
kg/ha).   These  authors  emphasized the importance of surface drying  in
releasing  readily  available  organic  matter,  which stimulates oxygen
consumption  and  provides  a  substrate  for denitrifying bacteria.   In
layers  that  remained permanently wet, even though the redox potentials
were very low, nitrate reduction was negligible.
Engler  and  Patrick  investigated  nitrate  removal   from floodwater in
relatively undisturbed cores of a fresh water swamp soil  and a saltwater
marsh soil in Louisiana [75].  The latter was more effective in nitrogen
removal,  with an average rate of a.2 Ib/acre-d (9.2 kg/ha-d), while the
fresh water swamp soil removed 2.9 Ib/acre-d (3.3 kg/ha-d).  Addition of
organic matter to a rice soil was shown in other experiments to have the
effect  of  decreasing  the  depth  of soil through which nitrate had to
diffuse before being reduced, and this drastically increased the rate of
nitrate removal.
A. 5  Summary
The  important  processes  involved  in nitrogen removal  from wastewater
applied   to   land  are  ammonia  volatilization,  crop  removal,   soil
adsorption  of  ammonium,  incorporation into the soil  organic fraction,
and  denitrification.  The relative contribution of individual processes
to  overall  nitrogen  removal  is  dependent on a large number of  soil,
climatic,  and  management  parameters.  While it is not yet possible to
predict nitrogen removal in a particular situation with a high degree of
confidence,  enough  is known about the influence of management factors,
such  as  loading  rates, flooding and drying periods,  and type of  plant
cover,  to  design  systems  that  will  remove  the major part of  input
nitrogen   for  a  wide  variety  of  disposal  requirements  and  local
circumstances.
                                    A-28

-------
A.6  References
 1.  Schloesing,  T. and A. Muntz.  Sur la Nitrification Par la Ferments
     Organises.  Compt. Rend. Acad. Sci. Paris.  84:301-303, 1877.

 2.  Alexander,  M.,  K.C.  Marshall,  and  P.  Hirsch.   Autotrophy and
     Heterotrophy  in  Mitrification.   (Presented at the Trans. Intern.
     Cong. Soil Sci. 7th Cong.  Madison.  2:586-591, 1960.)

 3.  Ardakani,  M.S., R.K. Schulz, and A.D. McLaren.  A Kinetic Study of
     Ammonium  and  Nitrite  Oxidation  in a Soil  Field Plot.  Soil  Sci.
     Soc. Amer. Proc.  38:273-277, 1974.

 4.  Broadbent,  F.E.,  K.6.  Tyler,  and  G.N.  Hill.  Nitrification of
     Ammoniacal  Fertilizers  in  Some  California   Soils.   Hilgardia.
     27:247-267, -1957.

 5.  Frederick, L.R.  The Formation of Nitrate From Ammonium Nitrogen in
     Soils:   I.   Effect  of  Temperature.   Soil Sci. Soc. Amer.'Proc.
     20:496-500, 1956.

 6.  Lance,  J.C.,  F.D.  Whisler, and H. Bouwer.   Oxygen Utilization in
     Soils Flooded With Sewage Water.  Journal of Environmental Quality.
     2:345-350, 1973.

 7.  Lance,  J.C.  and  F.D.  Whisler.  Nitrogen Balance in Soil Columns
     Intermittently  Flooded With Secondary Sewage Effluent.  Journal  of
     Environmental Quality.  1:180-156, 1972.

 8.  Bouwer,  H.,  J.C. Lance, and M.S. Rigys.  High Kate Land Treatment
     II.   water  Quality  and  Economic Aspects of the Flushing Meadows
     Project.  Jour. WPCF.  46:b44-859, 1974.

 9.  Robeck,  G.G., et al.  Factors Influencing the Design and Operation
     of  Soils  Systems  for  Waste Treatment.  Jour. WPCF.  36:971-983,
     1964.

10.  Broadbent,   F.E.,   D.  Pal,  and  K.   Aref.   Nitrification   and
     Denitrification  in  Soils  Receiving  Municipal  Wastewater.    In:
     Wastewater  Renovation  and  Reuse.  D'ltri,  F.M. (ed.).  New  York,
     Marcel Dekker, Inc.  1977.  pp 321-347.

11.  Bouwer,  H.   Renovating Secondary Effluent by Groundwater Recharge
     With  Infiltration   basins.    In:   Recycling  Treated  Municipal
     Wastewater  and  Sludge  Through  Forest  and Cropland.  University
     Park, Pennsylvania State University Press.  1973.  pp. 164-175.

12.  Amer, F.M. and W.V. Bartholomew.  Influence of Oxygen Concentration
     in Soil Air on Nitrification.  Soil Science.   71:215-219, 1951.
                                  A-29

-------
13.  Starr,   J.L.,   F.E.    Broadbent,   and   D.R.    Nielsen.    Nitrogen
     Transformations  During  Continuous  Leaching.   Soil  Sci.  Soc.  Amer.
     Proc.  38:283-289, 1974.

14.  Wild,  H.E.,  C.N.  Sawyer,   and T.C.   McMahon.   Factors Affecting
     Nitrification Kinetics.  Jour.  WPCF.  43:1845-1854,  1971.

15.  Hunt,  P.G.  and C.R.  Lee.    Overland  Flow Treatment  of Wastewater--
     A  Feasible   Approach.     In:     Land Application  of Wastewater.
     (Proceedings of a Research Symposium  Sponsored  by  the  USEPA,  Region
     III.   Newark, Del.  November 1974.)

16.  Mahendrappa,  J.K.,  R.L.  Smith, and  A.T.  Christiansen.   Nitrifying
     Organisms Affected by Climatic  Region in the  Western United States.
     Soil  Sci. Soc. Amer.  Proc.  30:60-62, 1966.

17.  Tyler,  K.B.,  F.E.  Broadbent,  and  G.N.  Hill.    Low Temperature
     Effects  on   Nitrification in Four California Soils.  Soil  Science.
     87:123-129,  1959.

Ib.  Broadbent,  F.E.   Nitrification and Denitrification of Municipal
     Wastewater  Effluents Disposed  to Land.   Report to California  State
     Water Resources Control Board.   February 1976.

19.  Kardos,  L.T.  and W.E. Sopper.  Renovation of  Municipal  Wastewater
     Through  Land Disposal  by Spray Irrigation.   In:   Recycling Treated
     Municipal  Wastewater  and  Sludge   Through   Forest  and  . Cropland.
     University Park,   Pennsylvania State University Press.   1973.  pp.
     148-163.

20.  Focht,  D.D.  and  H.   Joseph.    Microbial Denitrification Rates in
     Soil.   Annual Report to National Science Foundation.   Grant Number
     GI34733X.  1973.  pp.  211-220.

21.  Gilmour,  C.M., F.E.  Broadbent, and  S.M. Beck.   Recycling of Carbon
     and  Nitrogen  Through Land  Disposal  of  Various Wastes.   In:   Soils
     for  Management  and Utilization of  Organic Wastes and Wastewaters.
     Madison, American Society of Agronomy.   1977.

22.  Rolston,  D.E.,  M.  Fried,   and D.A.   Goldhamer.  Denitrification
     Measured Directly From Nitrogen and  Nitrous Oxide  Gas  Fluxes.   Soil
     Soc.  Amer. Jour.  40:259-266, 1976.

23.  McGarity,   J.W.  and  R.J.K.    Myers.    Denitrifying   Activity  in
     Solodized  Solonetz  Soils  of   Eastern   Australia.  Soil Sci. Soc.
     Amer-. Proc.   32:812-817, 1968.

24.  Stanford,  G.,  R.A.   Vander  Pol,,  and  S. Oziena.  Denitrification
     Rates  in Relation to Total  and Extractable Carbon.  Soil Sci. Soc.
     Amer. Proc.   39:284-289, 1968.
                                  A-30

-------
25.  Mann,  L.D., et al.   Increased Oenitrification in Soils by Addition
     of  Sulfur  as an Energy Source.  Journal  of Environmental Quality.
     1:329-332, 1972.

26.  Law,  J.P.,  Jr.,  R.E. Thomas, and L.H.  Myers.  Cannery Wastewater
     Treatment  by  High Rate Spray on Grassland.  Jour. WPCF.  42:1621-
     1631, 1970.

27.  Skerman,  V.B.D.  and  I.C. MacRae.  The  Influence of Oxygen on the
     Reduction of Nitrate by Adapted Cells of  Pseudotnonas dem'trificans.
     Canadian Journal of Microbiology.  3:215-230, 1957.

28.  Skerman,   V.B.u.  and  I.C.   MacRae.   The  Influence  of  Oxygen
     Availability  on  the  Degree  of  Nitrate Reduction by Pseudomonas
     denitrificans.  Canadian Journal of Microbiology.  3:505-530, 1957.

29.  Klausner,  S.L).  and  L.T.  Kardos.  Oxygen Relationships in a Soil
     Treated  With  Sewage  Effluent.  Journal  of Environmental Quality.
     4:174-17tf,  1975.

30.  Stensel,  H.D., R.C. Loehr, and A.W. Lawrence.  Biological Kinetics
     of  Suspended  Growth  Denitrification.   Jour.  WPCF.   45:244-261.
     1973.

31.  Bremner,  J.M.  and  K. Shaw.  Denitrification in Soil  II.  Factors
     Affecting  Denitrification.   Journal of Agricultural Science.  51:
     40-52, 1958.

32.  Nommik, ri.  Investigations on Denitrification in Soil.   Acta Agric.
     Scand. VI.  2:195-226, 1956.

33.  Wijler,  J.  and C.C. Delwiche.  Investigations on the  Denitrifying
     Process in Soil.  Plant and Soil.  5:155-169, 1954.

34.  Cooper,  G.S.  and  R.L. Smith.  Sequence of Products Formed During
     Denitrification  in  Some  Diverse  Western  Soils.  Soil Sci. Soc.
     Amer. Proc.  27:659:662, 1963.

35.  Volz,  M.G.,  et  al.   Nitrate  Reduction and Associated Microbial*
     Populations   in   a   Ponded  Hanford  Sandy   Loam.   Journal   of
     Environmental Quality.  4:99-102, 1975.

36.  Woldendorp,  J.W.  The Quantitative Influence of the Rhizosphere on
     Denitrification.  Plant and Soil.  17:267-270,1962.

37.  Stefanson, R.C.  Soil Denitrification in  Sealed Soil- Plant Systems
     I.   Effect  of  Plants, Soil Water Content and Soil Organic Matter
     Content  Plant anu Soil.  33:113-127, 1972.

38.  Woldendorp, J.W. The Influence of Living  Plants on Denitrification.
     Medcal.  Landbouwhogeschool, Wageningen 63(13)1-100, 1963.
                                 A-31

-------
39.  Terman,  G.L.  and M.A. brown.  Crop Recovery of Applied Fertilizer
     Nitrogen.  Plant and Soil.  29:48-65, 1968.

40.  Burton,  G.W.  and  J.E.  Jackson.  Effect of Rate and Frequency of
     Applying  Six  Nitrogen Sources on Coastal  Bermuda Grass.  Agronomy
     Journal.  54:40-43, 1962.

41.  Broadbent, F.E.  Unpublished Data, 1976.

42.  Sopper,  W.E.  and L.T. Kardos.  Vegetation Responses to Irrigation
     With   Treated  Municipal   Wastewater.    In:   Recycling  Treated
     Municipal  Wastewater  and  Sludge  Through  Forest  and  Cropland.
     University Park, Penn. State Univ. Press, 1973.  pp.  271-294.

43.  McKim,   H.L.,  et   al.   Use  of  Land  Treatment  in  Wastewater
     Management.  Agronomy Abstract,  p. 34, 1974.

44.  Karlen, D.L., M.L. Vitosh, and R.J. Kunze.   Irrigation of Corn With
     Simulated  Municipal  Sewage  Effluent.   Journal   of Environmental
     Quality.  5:269-273, 197b.

45.  Parizek,  R.R.,  et  al.   Pennsylvania  State  Studies  Wastewater
     Renovation and Conservation.  Pennsylvania  State University Studies
     No. 23 (University Park) 1967.

46.  Scott,   V.H.    Sprinkler   Irrigation.    California  Agricultural
     Experimental  Station  Extension  Service   Circular.   Publication
     Number 456.  1956.

47.  Henderson,  D.W.,  C.  Bianchi, and L.D.  Doneen.  Ammonia Loss From
     Sprinkler Jets.  Agricultral Engineering  36:398-399, 1955.

48.  Meyer,  R.D.,  R.A.  Olson,  and H.F. Rhoades.  Ammonia Losses From
     Fertilized Nebraska Soils.  Agronomy Journal.  53:241-244, 1961.

49.  Mills,   H.A.,   A.V.    Barker,   and   D.N. Maynard.  Ammonia
     Volatilization From Soils.  Agronomy Journal.  66:355-358, 1974.

-60.  Martin,  J.P.  and  H.u.  Chapman.   Volatilization of Ammonia From
     Surface Fertilized Soils.  Soil Science.   71:25-34, 1951.

51.  Ryan,  J.A. and L).R. Keeney.  Ammonia Volatilization From  Surface-
     Appliea Waste Water Sludge.  Jour. WPCF.   47:386-393, 1975.

52.  Broadbent,  F.E.  and  F.  Clark.    Denitrification.    In:   Soil
     Nitrogen.   Madison,  American Society of Agronomy. 1965.  pp. 344-
     359.

53.  Olson,  R.J.,  R.F.  Hensler,  and  O.J.   Attoe.   Effect of Manure
     Application,  Aeration  and Soil ph on Nitrogen Transformations and
     on  Certain  Soil Test Values.  Soil Sci. Soc. Amer.  Proc.  34:222-
     225, 1970.
                                  A-32

-------
54.  Meek,  B.D.,  et al.  The Effect of Large Applications of Manure on
     Movement  of  Nitrate  and  Carbon  in  an  Irrigated  Desert Soil.
     Journal  of Environmental  Quality.  2:b9-92,  1974.

55.  Lance, J.C.,  F.D. Whisler, and R.C. Rice.  Maximizing Denitrifica-
     tion During Soil Filtration of Sewage Water.  Journal of   Environ-
     mental Quality.  5:102-107, 1976.

56.  Field  Evaluation  of  Anaerobic  Denitrificatipn in Simulated Deep
     Ponds.   California  Department Water Resources Bulletin,  pp. 174-
     179, 1969.

57.  Hoeppel,  R.E.,  P.G.  Hunt,  and  T.B.  Delaney,   Jr.   Wastewater
     Treatment  on  Soils  on  Low  Permeability.  U.S. Army Engineering
     Waterways  Experiment  Station,  Miscellaneous  Paper.  Publication
     Number Y-74-2.  1974.

5b.  Carlson,  C.A.,  P.G.  Hunt,  and  T.b. Delaney, Jr.  Overland Flow
     Treatment   of   Wastewater.    U.S.   Army   Engineering  Waterways
     Experiment Station.   Miscellaneous Paper.  Publication Number Y-74-
     3.  1974.
           «
59.  Thomas,  R.E., et al.  Feasibility of Overland Flow for Treatment of
     Raw  Domestic  Wastewater.  Environmental Protection Agency,  Office
     of Research and Development.  EPA-660/2-74-087.  July 1974.

60.  Nomrnik,   H.   Ammonium  Fixation  and  Other  Reactions Involving a
     Nonenzymatic Immobilization of Mineral Nitrogen in Soil.  In:  Soil
     Nitrogen.   Madison, American Society of Agronomy.  1965.  pp. 198-
     25b.

61.  Burge,  W.D.  and  F.E.  Broadbent.  Fixation of Ammonia by Organic
     Soils.  Soil Sci. Soc. Amer. Proc.  25:199-204, 1961.

62.  Lance,  J.C.   Fate of Nitrogen in Sewage Effluent Applied to Soil.
     Journal  of the Irrigation and Drainage Division, Proceedings  of the
     ASCE.  101:131-144,  1975.

63.  Sullivan,  R.H.,  M.M. Conn, and S.S. Baxter.  Survey of Facilities
     Using Land Application of Wastewater.  EPA 430/9-73-006.  1973.

64.  Allison,  F.E.    The Enigma  of  Soil  Nitrogen   Balance Sheets.
     Advances in Agronomy.  7:213-250, 1955.

65.  Adriano,   D.C.,  P.F.  Pratt,  and  F.H.   Takatori.   Nitrate  in
     Unsaturated  Zone  of  an  Alluvial  Soil in Relation to Fertilizer
     Nitrogen  Rate  and  Irrigation  Level.   Journal   of Environmental
     Quality.  1:41b-422, 1972.

66.  Sopper,   W.E.  A Decade of Experience in Land Disposal of Municipal
     Wastewater.   Proceedings  of  the  Symposium  on Land Treatment of
     Secondary  Effluent.  Ft. Collins, Colorado  State University, 1973.
     p. 19-61.
                                 A-33

-------
67.  Johnson,  R.D., et al.   Selected Chemical  Characteristics of Soils,
     Forages  and Drainage Water From the Sewage Farm Serving Melbourne,
     Australia.  U.S.  Department of  the  Army.   January 1974.

68.  Adriano,  D.C.,  et al.   Effect of  Long Term Land Disposal  by Spray
     Irrigation of Food Processing Wastes on Some Chemical  Properties of
     the  Soil   and Subsurface Water. Journal  of Environmental  Quality.
     4:242-248, 1975.

69.  Merrell,  J.C.,  Jr.,   A.  Katko,  and  H.E.  Pintler.   The Santee
     Recreation Project, Santee, Calif.   Public Health Service.    Publi-
     cation Number 99-WP-27.   1965.

70.  Larson,  W.C.   Spray  Irrigation  for  the Removal  of Nutrients in
     Sewage  Treatment  Plant  Effluent   as  Practiced  at Detroit Lake,
     Minnesota.   In:    Algae  and  Metropolitan  Wastes.    Transactions
     Seminar, U.S. Dept. HEW, 1960.   pp.   125-129.

71.  Bendixen,  T.W., et al.   Ridge and Furrow Liquid Waste Disposal  in a
     Northern  Latitude.   Journal of the Sanitary Engineering Division,
     Proceedings of the ASCE.  94:147-157,  1968.

72.  Satterwhite,  M.B.  and   G.L. Stewart.  Treatment of  Primary Sewage
     Effluent  by  Rapid  Infiltration  in   a  New  England Environment.
     Agronomy Abstract.  1974, p. 38.

73.  Broadbent,  F.E.   and M.E.  Tusneem.   Losses of Nitrogen From Some
     Flooded  Soils  in  Tracer Experiments.  Soil  Sci. Soc.  Amer. Proc.
     35:922-926, 1971.

74.  Raven,  A.  and Y. Avnimelech.   Minimizing Nitrate Seepage  From the
     Hula Valley into  Lake Kinnaret  (Sea of Galilee): 1.   Enhancement of
     Nitrate   Reduction   by  Sprinkling  and   Flooding.    Journal   of
     Environmental Quality.   2:455-458,  1973.

75.  Engler,   R.M.,  and  W.H.  Patrick,   Jr.   Nitrate   Removal  From
     Floodwater  Overlying  Flooded   Soils   and  Sediments.   Journal  of
     Environmental Quality.   3:409-413,  1974.
                                  A-34

-------
                               APPENDIX B

                               PHOSPHORUS
B.I  Introduction
Phosphorus  (P),  in the element form, is a highly reactive material  and
is thus usually found in nature in an oxidized state in combination with
oxygen  and  a  number  of  mineral  elements.   It is also found in   many
organic  compounds  in  naturally  occurring  materials.   Because  phos-
phorus is  essential for all forms of life, it must be present in avail-
able forms  in all soils and waters if these are to be biologically pro-
ductive.  The  production  of  large  amounts of biological  materials on
land  surfaces is usually considered desirable because these can be used
for  food, fiber, fuel, and building materials.  In waters,  however,  the
production  of  large amounts of biological materials usually causes  un-
desirable effects.   Thus,  on  agricultural  land, materials containing
phosphorus  are added to increase biological production;  whereas in most
waters,  attempts  are  made to keep the phosphorus concentration within
low  limits  to  avoid  undesirable production of organic materials that
cause  problems  in  the  use  of water for municipal, industrial,  agri-
cultural, and recreational purposes.


Concentrations of phosphorus in municipal wastewaters usually range from
about  1.0  to 40 mg/L, depending on the phosphorus concentration of the
input  water and removal during treatment [1-3].  Thomas  used 10 mg/L as
a typical phosphorus concentration [4].  Most concentrations are usually
less than 20 mg/L.


On  the other hand, the concentration of phosphorus in the soil  solution
in  most  soils is usually between 3 and 0.03 mg/L [5], but typical  con-
centrations are  a few tenths mg/L [6].  Because of these differences in
ranges  of  phosphorus concentrations between wastewaters and soil  solu-
tions, a  reduction in phosphorus concentration as the wastewater enters
the  soil  is  to  be  expected.   As a result of various adsorption  and
precipitation  reactions,  the concentration of phosphorus will  decrease
as  the  wastewater enters the soil, depending on the intensity of  these
reactions,  the capacity of the soil materials to maintain them, and  the
time  allowed for them to proceed.  Harvested crops also  serve as a sink
for  the added phosphorus and a certain amount returns to the soil  annu-
ally in  plant  materials  (roots,  stems, and leaves) that are not har-
vested.
The  objectives  of  this appendix are to discuss the reactions of phos-
phorus with  soils,  to  show their applications to the removal of phos-
phorus  from  wastewaters  applied  to  soils, and to assess the present
status  of  our  abilities  to predict the capacities of soils to remove
phosphorus  from  such  waters.   The  chemistry of phosphorus in soils,
                                  B-l

-------
plants,  and  waters is complex, and the literature is voluminous.   Con-
sequently, no  attempt  has  been  made to provide a complete literature
review.   Reports and textbooks that do review the literature are  avail-
able, including Russell [5], Tisdale and Nelson [7], Larson [6], Holt et
al. [8], and Ryden et al. [9].
B.2  Removal Mechanisms
The phosphorus that enters a soil  in fertilizers,  wastes,  or  wastewaters
is (1) removed in harvested crops;  (2)  accumulated in  the  soli a  phase  of
the  soil as organic compounds,  adsorbed ions,  or  precipitated inorganic
compounds;  (3)  removed  by soil  erosion as soluble phosphorus  or  phos-
phorus adsorbed  or  precipitated  on soil  particles; or (4) leached from
the  root  zone  in  percolating  water.  The chemical  reactions between
added  soluble  phosphorus and soil  materials or sediments influence the
availability  of phosphorus to crops and the desorption or solubility  of
phosphorus  when  the  soil  materials   become   sediments  in  streams and
lakes, and control  the leaching  of phosphorus through  soil  profiles.
The  amount of phosphorus in soils is usually  between  0.01  and  0.2%,  but
heavily  fertilized  surface soils can contain greater amounts.   Usually
much  less  than  0.1%  of  the  total  phosphorus in soils  is soluble in
water.   Solid  phase phosphorus consists of (1)  organic  phosphorus,  the
quantities of which are highly dependent on  the amount of organic matter
in  the  soil;  (2) inorganic  compounds; and  (3) phosphorus adsorbed on
various  types  of  surfaces  in  the soil.  The  orthophosphate  form,  in
which  one phosphorus atom is combined with  four  atoms of oxygen, is  the
most stable configuration in the soil  environment.
In  discussing  the reactions of phosphorus  with soils  and  sediments,  it
is  assumed  that  the phosphorus is in  the  orthophosphate  form  and  that
other  forms  convert to this form in the soil  system [10-13].   The  main
soil  constituents  that react with phosphorus  at concentrations usually
found  in  wastewaters are (1) iron and  aluminum as soluble ions,  oxides
and  hydroxides,  and silicates; and (2)  calcium as a soluble  ion  and  as
carbonate.
Soluble  inorganic  phosphorus  introduced into a soil  is  chemically  ad-
sorbed on  surfaces  and  can  also  be precipitated.   In  the  adsorption
processs,  the  reaction is with iron,  aluminum, or calcium ions  exposed
on solid surfaces.  Reactive iron and aluminum  surfaces can occur at  the
broken edges of crystalline clay minerals, as surface  coatings of oxides
or  hydroxides on crystalline clays,  and.at the surfaces of particles of
oxides  and hydroxides and of amorphous silicates.   Aluminum in the form
of  positively  charged hydroxide polymers and  as an exchangeable ion in
acid  soils  can  also adsorb phosphorus.   Reactive calcium surfaces  are
mainly  found  on  solid  calcium  carbonates and calcium-magnesium car-
bonates.  Precipitation reactions occur with soluble iron, aluminum,  and
                                  B-2

-------
calcium.   Particles  of phosphate compounds can also form by separation
of adsorbed  phosphorus along with iron, aluminum, or calcium from solid
surfaces.
The  reactions of phosphorus with soils are complex, and the soil  system
is  complex.   Consequently, the uncertainty whether phosphorus is being
adsorbed  or precipitated leads to the use of the term "sorption," which
covers  both  processes  and means only that the phosphorus has been re-
moved from solution.


A  given  soil material does not have a fixed capacity to sorb the phos-
phorus added  in  wastewaters.   Sorption  is  dependent not only  on the
concentration of  phosphorus  in  solution,  but  also  on  a  number of
factors, including soil ph, temperature, time, the total amount of phos-
phorus added,  and  the  concentrations  of  various constituents  in the
wastewater  that  directly  react with phosphorus or that influence such
soil  properties  as  pH  and oxidation-reduction cycles.  Another basic
factor  is that the downward movement of phosphorus in a soil  profile is
diffuse.   Because  the  capacity  for  sorption  of  phosphorus is con-
centration-dependent,  there  is  a large transition zone between  highly
enriched  and  nonenriched  soil, which is described as a diffuse  rather
than  as  an abrupt boundary as illustrated in Figure  B-l.   That is, a
given  depth  interval  gradually  accumulates  sorbed and soluble phos-
phorus, and  the  breakthrough  curve  at  the  bottom  of a soil  column
extends over considerable time and/or volume of effluent.
     B.2.1  Crop Removal


In most cropped soils, the application of phosphorus increases growth of
plants.   However, as more phosphorus is accumulated (i.e., excesses are
added),  negative  effects  are sometimes found.  These decreased yields
that  result  from  excess available phosphorus in the soil are indirect
effects  of phosphorus on the availability of copper, iron, and zinc and
are  referred  to  as nutrient imbalances [14-17].  Corrections of these
imbalances  can  be  made  by  soil or foliar applications of the needed
elements.
The  removal  of  phosphorus in harvested crops depends on the yield and
the  phosphorus  concentration  in the harvested material, which in turn
are  dependent  on  the crop, soil, climate, and management factors, in-
cluding the  amount  of  phosphorus  added  to the soil.  Typically, the
harvested  portions of annual crops contain only 10% or less of the fer-
tilizer phosphorus  added  during the season in which the crop is grown,
but recoveries as high as 50 to 60% are possible [5].  However, recovery
is  low  not  only  because the soil reacts with the added phosphorus to
make  it  less  available,  but  also because plants absorb considerable
amounts  of  phosphorus  from soil supplies, including the residues from
applications  in  previous years.  Thus, the total removal per year as a
                                   B-3

-------
fraction  of the total added per year  is  more important than  the  recovery
of that added during the year the crop is grown.
                                FIGURE  B-l

            RELATIONSHIPS BETWEEN PHOSPHORUS CONCENTRATION AND
               SOIL DEPTH FOR ABRUPT AND  DIFFUSE BOUNDARIES
                   BETWEEN ENRICHED AND NONENRICHED SOIL
                           PHOSPHORUS IN SOLUTION, mg/L
                                 INCREASING
                                 CONCENTRATION
SOIL
SURFACE
 APPLIED
 CONCENTRATION

10



-••• 	 'vrr~ A

	 \ £ - t
on 	 \.-__

":::::::::: "i :r "
:::::::::::::: .YE :


"::::::::: :~ :: : :\


E 	 \
« 60 — 	 l;
?
H-
0.
UJ
a
U"
i ' U»^
so - y
W\-u
f El*
r
r
1 20- /
i sn 	
::::::::::::::::::::::::::::::::: --jd
============================================

BRUPT BOUNDARY BETWEEN 	 ,

NKIOHtU ANU NUNtNKIbHtU 5UIL 	 ;K 	
" • , i 	 " .. . , r





t **


1 ^~^^
y
FFUSE BOUNDARY BETWEEN
RICHED AND NONENRICHED SOIL
                                    B-4

-------
Data  for  amounts  of phosphorus removed by the  usual  harvested  portions
of selected agronomic, vegetable, and fruit crops are  presented  in Table
B-l.   Variations   range  from as low  as 10 lb/acre-yr (11  kg/ha-yr) to as
high  as 85 .lb/acre-yr (95  kg/ha-yr).
                                   TABLE  B-l

                REMOVAL OF  PHOSPHORUS  BY THE USUAL HARVESTED
                          PORTION OF SELECTED CROPS
                        Crop
.Annual crop    Phosphorus
   yield,       uptake,
  per acre    lb/acre-yr
Corn [18]
Cotton [18]
Lint and
seed
Wheat [18]
Rice [18]
Soybeans [18]
Grapes [18]
Tomatoes [18]
Cabbage [18]
Oranges [18]
Small grain, corn-
hay rotation [19]
Reed canary grass [19]
Corn silage [19]
Poplar trees [20]
Barley-sudan grass
rotation for forages3
Johnson grass [18]
Guinea grass [18]
Tall fescue [18]
180 bu

3 700 Ib
80 bu
7 000 Ib
60 bu
12 tons
40 tons
35 tons
600 boxes
(90 Ib/box)





12 tons
11.5 tons
3.5 tons
31

17
20
20
22
10
30
16
10
29
40
27-36
23-62
75-85
84
45
29
                    a.  Unpublished data for barley in the winter
                       followed by sudan grass in the summer.
                       P.P.  Pratt and S. Davis, University of
                       California, and USDA-ARS, Riverside,
                       California.

                    1  Ib = 2.2 kg
                    1  acre =  0.405 ha
                                      B-5

-------
 Amounts   of   phosphorus   removed  by crops can range by an order of mag-
 nitude and   are   higher   with  forage  crops than with most other crops.
 Removal   in   harvested materials, as a fraction of that added, decreases
 as   the   amount   of   phosphorus  added increases.  Where double cropping
 during   a long   season   is  possible, removal can be nearly double that
 where only one crop can  be grown.
      B.2.2   Adsorption
 When   solutions  containing  soluble phosphorus at concentrations usually
 found   in   reclaimed  waters   (20  mg/L or less) are added to soils, the
 initial   (and more  rapid)  reaction can be described by the Freundlich or
 Langmuir   equations.    Slow  reactions,  such  as precipitation, are not
 modeled  by these  equations  so that their use will yield conservative
 results.    01 sen  and   Watanabe  found that, up to an equilibrating con-
 centration of  nearly   20  mg/L,  using a reaction time of 24 hours, the
 reaction   was  described   by   the Langmuir equation [21].  TKut is, if a
 water   containing   any  specific  concentration of phosphorus within the
 range   of  a few to  20 mg/L is  added to a soil and allowed to equilibrate
 for  24  hours,  phosphorus  will  be  sorbed  by  the soil and the con-
 centration in  solution will decrease.  If a number of waters containing
 various phosphorus  concentrations are added to samples of the same soil,
 a  relationship  between   phosphorus  sorption and final phosphorus con-
'centration can  be  described  by the Langmuir equation.  From this equa-
 tion the   decrease  in phosphorus concentration and the sorption of phos-
 phorus can  be  predicted  for any other initial concentration using the
 same   soil   and  reaction  time.   But  at  equilibrating concentrations
 greater  than  20 rng/L, the  reactions in most soils are not described by
 this equation.


 Larson concluded that,  in  dilute solutions, adsorption generally follows
 the  Langmuir  equation where a plot of C/V against C (where C is con-
 centration and V is phosphorus adsorbed per unit weight of soil) gives a
 straight   line  [6].    Larson  reported that a study of 120 soils showed
 straight  line relationships  of C/V to C up to concentrations of about 19
 mg/L   of   phosphorus.   Above this concentration the  C/V-C line  curved,
 indicating  that the adsorption equation was no longer valid.  At higher
 concentrations,  the concentration was assumed to be limited by the for-
 mation of  sparingly soluble  compounds, and the value V increased as more
 of these  compounds  were formed.


 Ellis   [13] and  Ellis and Erickson [22] used the Langmuir equation to
 calculate   relative capacities  of  soil profiles to retain phosphorus.
 The  retention  of  phosphorus at  a  solution concentration of 10 mg/L
 ranged from 71  to  95%  of  the adsorption maximum calculated from the
 Langmuir  equation for a number of soil materials.  Amounts retained from
 a  solution concentration  of 10 mg/L ranged from 77 to 1 898 Ib/acre (86
 to 2  126  kg/ha) for 12 in.  (30 cm) depth intervals, respectively, for a
 dune   sand  to  a   clay loam.  The reaction time in these studies was 24
 hours.
                                  B-6

-------
Even though the original  or initial  capacity to retain phosphorus  can  be
described by adsorption equations, the retention increases as a  function
of time so that the initial retention is only useful  if the ratio  of tne
slow  reaction to the initial  reaction is known for each soil.   The slow
reaction  involves the formation of precipitates of limited solubilities
and  the  regeneration  of adsorptive surfaces.  Crystallization of pre-
cipitates also  reduces  their solubilities.  Thus, there is small prob-
ability that  Langmuir  adsorption equations will  be generally useful  in
predicting  quantities  of  phosphorus  that  will  react with soils over
periods of months or years.


     B.2.3  Precipitation

The  dominant  precipitation  reactions in soils are with calcium, iron,
and  aluminum  ions.  Reactions of phosphates with iron and aluminum are
not  completely  identical,  but  they are sufficiently similar  that for
some parts of this discussion they are considered together.


Qualitative  and  quantitative  detenninations  of definite compounds  or
minerals  of  phosphorus  in  soils are difficult.   Empirical  extraction
techniques,  such  as  that of Chang and Jackson [23], have been used  to
semiquantitatively  differentiate  among  calcium,   aluminum,  iron, and
organic  phosphates.  More definite determinations of specific compounds
have  been  made  [24-28],  but  these are qualitative determinations  of
reaction  products formed from high concentrations of soluble phosphorus
usually  near  simulated fertilizer bands.  Another approach is  to study
the  formation  and  stability  of phosphorus compounds in solutions and
then assume that the same compounds form in soils under similar  chemical'
conditions, or to study phosphorus reactions with relatively pure  solids
and  assume  that  the  same  reactions  occur  in soils.  These various
approaches lead to the same generalities concerning phosphorus compounds
in soils.
The  dominant  factor that determines whether calcium phosphates  or  iron
and  aluminum  phosphates  form  in soils is the pH.   The phase diagrams
presented  by  Lindsay  and  Moreno for a number of phosphorus compounds
suggest that calcium compounds predominate above pH 6 to 7,  and iron and
aluminum  compounds  predominate  below  pH  6  to 7  [29].   The exact pH
cannot  be  specified  without  knowing the calcium ion activity  and the
calcium  phosphate  species  that is controlling the  solubility of phos-
phorus.  Larson  stated that, as the pH decreases, a  level  of acidity is
found at which calcium phosphates can no longer control  phosphorus solu-
bility, and  he suggested that this lower limit might be pH  5 [6].   This
limit  might  be  found  if  fluoroapatite is the calcium phosphate  con-
trolling the  phosphorus  concentration in solution,  whereas when hydro-
xyapatite or  octocalcium  phosphate is the controlling compound, the pH
limit  would  be near 6.  When dicalcium phosphate dihydrate is the  con-
trolling  calcium  compound,  the  pH  limit would be near 7. For these
limits, it is assumed that iron and aluminum are present in  the soil  and
compete  with  calcium  for  control  of the phosphorus solubility.   The
                                  B-7

-------
partial  pressure  of carbon dioxide in the soil  can influence the acti-
vity of calcium ions ana thus exert an effect on  a calcareous system.


The  usual  concentrations of iron and aluminum ions in solution,  in the
acid  pH  range  where iron and aluminum phosphates may form, are  so low
that  the  direct  precipitation  of iron and aluminum phosphates  is un-
likely. Concentrations  of  iron  and  aluminum  in the soil  solution of
moderately  acid  to  slightly alkaline soils, pH 5.5 to 8.0, are  in the
range  of a few fiq/L or in the parts per billion  range.  An exception to
this statement can be found in highly acid soils  containing exchangeable
aluminum  in sufficient quantities that direct precipitation of aluminum
phosphate  might  occur.   Exchangeable aluminum, measured by extraction
with  a  potassium  chloride  solution, in excess of about 20 ppm  in the
soil  can  be  expected to cause a direct precipitation of phosphorus as
amorphous  aluminum  phosphate.  A more general  pathway for formation of
iron  and  aluminum  compounds,  when dilute solutions of phosphorus are
added,  is  that  the  phosphorus first reacts by adsorption on surfaces
containing  reactive iron and aluminum, followed  by a breaking away from
the  surface  to  form  amorphous forms of strengite (iron phosphate)  or
variscite (alluminum phosphate), which then slowly crystallize into more
ordered and less soluble forms of these compounds.
There  is  thermodynamic  evidence  that the  phosphorus adsorbed on  iron
surfaces  is  stable in the well-aerated soils,  whereas surface films  of
phosphate  on  aluminum  surfaces  are not [5].   This suggestion is  that
aluminum  phosphates break away from surfaces, exposing a new surface  to
continue  the  adsorption process, whereas iron  phosphates do not follow
this  pattern.   Thus, well-aerated soils containing dominantly aluminum
materials  would  have  much higher capacities to retain phosphorus  than
soils  containing  dominantly  iron materials.   Taylor et al. found  that
iron  materials  were much less important than aluminum materials in the
initial  reactions  of ammonium phosphate with soils [30, 31].   If soils
undergo  alternate cycles of oxidation and reduction, surface iron phos-
phates are  more  unstable  than  those of aluminum because of cycles  of
reduction of iron to the ferrous form and oxidation to the ferric form.
In  contrast  to  the  situation  with iron and aluminum,  for which  con-
centrations in  the soil  solution are usually in the pg/L  range,  calcium
concentrations  are in the mg/L range.  Concentrations of  10  to 200  mg/L
are  common.   In neutral and alkaline soils irrigated with wastewaters,
calcium  concentrations are likely to be sufficiently  large that  calcium
phosphates  will  precipitate  directly.   Under alkaline  conditions and
calcium concentrations of 20 to 200 mg/L in the soil  solution, dicalcium
phosphate dehydrate can precipitate directly from solution, depending on
the pH and the phosphorus concentration.  This compound then  redissolves
and  the  less  soluble octocalcium phosphate forms.   With more time the
octocalcium phosphate is converted to the less soluble hydroxyapatite«


Another  significant  difference between the iron and  aluminum phosphate
system  and the calcium phosphate system, relative to  the  application of
                                   B-8

-------
wastewaters  to soils, is that these waters may have only traces of iron
and aluminum, but they usually have substantial amounts of calcium.  The
reactions  with  iron  and  aluminum are thus limited to the supplies of
these  in  the  soil  or  sediment, whereas the water may supply its own
calcium,  setting  up  a  system that can precipitate calcium phosphates
indefinitely.   In  calcareous  soils the calcium from calcium carbonate
can  also be a highly significant source for precipitation of phosphorus
over an extended period of time.
The reactions of phosphorus with organic soil  are qualitatively the same
as  in  mineral  soils, but the capacities for sorption are usually much
smaller.   Many  organic soils have small  quantities of iron and/or alu-
minum and  calcium and thus are not highly suitable for removal  of phos-
phorus from  wastewaters.  There are organic soils that have accumulated
iron  and  aluminum  materials  that have relatively large capacities to
sorb  phosphorus and there are calcareous organic soils that will  retain
phosphorus.   However,  as  a  general   rule,  mineral  soils will  be more
suitable for removal of phosphorus from wastewaters.
     B.2.4  Reaction Rates
The initial adsorption of phosphorus from dilute solutions is rapid.   An
apparent  equilibrium is attained in a few days [32-35].   But, following
this  apparent  equilibrium,  there are slow reactions that continue  for
months 'or  years [10, 36-47].  Ellis and Erickson found that most soils
recovered  their  sorptive  capacities  in about 3 months [22].   Kao  and
Blanchar  found  that  the adsorptive capacity of the Mexico soil  of  the
Sanborn  field  at Columbia, Missouri, had changed little after 82 years
of phosphate fertilization [48].  Barrow and Shaw found that the rate of
the  slow  reaction  decreased dramatically as the temperature decreased
[35].
This slow reaction is perhaps mostly the result of the precipitation and
crystallization of highly insoluble compounds, such as the conversion of
dicalcium   phosphate   dehydrate  to  octocalcium  phosphate  or hydro-
xyapatite, and  the  exposure  of  fresh  adsorptive surfaces where pre-
viously adsorbed  phosphates slough off from surfaces of soil particles.
The relationship between adsorption and precipitation can be illustrated
by the equilibrium reaction [6]:

         P adsorbed^J> in solution-^? precipitated       (B-l)
If  soluble  phosphorus  is  added or removed, the immediate reaction is
with the phosphorus adsorbed, but at equilibrium;  the precipitated forms
control  the  phosphorus  in  solution.   Equilibrium  is  attained very
slowly,  however,  and  under  conditions of irrigation with wastewaters
where phosphorus is added periodically if not continuously, the reaction
will  be to the right, and the system will be continuously in a state of
                                  B-9

-------
disequilibrium.   DeHaan reported that the adsorptive capacity of  a  soil
was  too  small  to  account for the  large amount retained  and suggested
that  adsorption  occurred  during the  application  stage  and that  pre-
cipitation took  place  during  the resting stage with a  regeneration of
the adsorptive capacity [49].
     B.2.5  Leaching


The  leaching of phosphorus from the  root zone  of a  cropped  land area or
from  the  surface  soil   material  in   any  wastewater  treatment project
depends  on  the  amount  of  water that moves  across the  boundary being
considered  and the phosphorus concentration in that volume.  The amount
leached may be calculated as follows:

          Amount leached = 0.225 WC  (U.S. customary units)     (B-2)
          Amount leached = 0.1 WC  P(SI  units)                  (B-2a)

where amount leached is in Ib/acre-yr (kg/ha-yr)
      W = water that moves across the boundary, in./yr  (cm/yr)
     C  = concentration of phosphorus, mg/L

Because  volumes  of  percolating water  are  small  and concentrations are
low,  the downward movement of phosphorus in croplands  is  usually a very
slow  process.   If  12  in.  (30  cm)   of water percolates  past a given
boundary in the soil profile and the  concentration of phosphorus in this
water  is  0.2  mg/L,  as  might  be  the case in well-fertilized fertile
soils,  the  amount  of  phosphorus leached  is  0.54  Ib/acre  (U.6 kg/ha).
The  amounts  of  phosphorus  absorbed   by  plant roots from  soil depths
beneath  the zone, of incorporation of added  phosphorus  more  than balance
this  amount.   Thus,  under  usual fertilizer  practices in  agricultural
lands, the net leaching of phosphorus is usually very small.
However, in rapid infiltration systems where large  volumes  of water move
through  the  soil  per year, the quantities of  phosphorus that  leach can
be  orders of magnitude higher than, is usual  for croplands.  Under these
conditions of high  rates, the limiting factor is the  solubility of phos-
phorus, which  is controlled by the capacity of the soil to retain phos-
phorus (i.e., adsorption, precipitation,  and reaction rates).
B.3  Phosphorus Removal  by Land Treatment Systems
Land  application has been used for centuries,  and there are  hundreds of
systems  in  use  in the United States today.   Although soil  phosphorus,
the  reactions  of fertilizer phosphorus with  soils,  and the  movement of
phosphorus  with  surface  flows  and with leaching waters  have  been the
subject  of  many  reports  during  the past few decades, studies  of the
behavior  of  phosphorus in land application systems  have been initiated
only  in  the past few years.  Thomas reported  in 1973  that historically
                                 B-10

-------
the effects  of  land  treatment  approaches  on  plant life,  soils,  and
groundwater   had not received much attention [50].   Thus, because tech-
nical questions  dealing  with  the behavior of phosphorus during waste-
water applications  to  lands  have  been asked only recently, there  are
very  few  reports  on phosphorus retention by soils in land application
systems.


     B.3.1  Slow Rate Systems
Slow  rate  systems,  as  defined in Chapter 2, are those in which  total
wastewater  applications  range  from 2 to 20 ft/yr (0.6 to 6.1  m/yr)  at
weekly  rates  of 0.5 to 4 in. (1.2 to 10 cm).  A vegetative cover  is  an
integral  component  of  the  system anu can utilize phosphorus  for crop
growth  in accordance with typical  values given in  Table B-l.    because
the  application  rates  are  similar  to  those studied in agricultural
systems,  much  of  the  information  gained  from agricultural  study  is
applicable  to  slow  rate treatment systems.  Even though phosphorus  is
removed  from  solution  rapidly  in slow rate systems by adsorption and
precipitation,  it  is  useful to quantify these numbers for engineering
design   purposes.   Wastewater  applications  are  usually  limited  by
nitrogen  or  hydraulic  considerations on a short-term basis, but  phos-
phorus application may be a limiting factor over the life of the system.
For  the  purposes  of  this design manual, it is useful  to know the  net
phosphorus  application  to  the  soil, i.e., the quantity of phosphorus
applied  in  the  wastewater  after  the removal  by crops is considered.
This value is useful in estimating the life of system in  accordance with
the empirical model presented in Section B.4.4.
Crop  removal  as a factor in predicting a net application of phosphorus
on  land is illustrated graphically in Figure B-2,  which shows the  rela-
tionships among  crop  removals in pounds per acre  per year,  total  phos-
phorus applications, and the net application to soil.


The  net  application  to the soil is important in  estimating phosphorus
sorption as a prediction of the life of the system  to  retain  phosphorus.
An empirical  model  uses  Figure B-2 as  input into  computing  an estimate
of long-term phosphorus retention.


Because  of  the  similarity  of slow rate systems  to  usual practices  on
croplands,  much  of  the  information obtained on  the behavior of  phos-
phorus in crop production is applicable.  A number  of  studies have  shown
that  the  retention  of  phosphorus near the place of its incorporation
into  soils  is  high,  i.e., the movement is slow, except in acid  sandy
soils  and  in  acid organic soils containing only  small  amounts of iron
and  aluminum  [5,   19, 51-56].  In addition, the transfer of phosphorus
from  land  areas  to  streams,  for lands protected from excessive soil
                                 B-ll

-------
     500
     400
CD

O
ea
     300
     200
     1 00
                                FIGURE B-2

                       NET  PHOSPHORUS APPLICATION
                                TO THE SOIL
PHOSPHORUS REIOVED BY CROP,
        Ib/acre-yr
       (TABLE B-1)
                    100
                                 200
     300
400
500
                  PHOSPHORUS  APPLIED IN NASTEWATER, Ib/acre.yr


         1  lb/acre= 1.12 kg/ha
                                  B-12

-------
erosion,  is  usually less than 1.0 lb/acre-yr (1.1  kg/ha-yr)  [8,  9,  57-
61].  These  small  amounts are insignificant in terms of the  efficiency
of  use  of  phosphorus by plants and they are small  when expressed as  a
percent  of  the phosphorus sorbed by the soil.   In  terms of the quality
of the drainage water, however, these small  amounts  of phosphorus  can be
signficant,  as illustrated in Figure B-3.  If phosphorus concentrations
greater  than  0.030  rng/L  are  conducive  to algal  blooms in lakes  and
streams,  some  streams  that  contain  mainly  drainage, including both
surface  runoff  and  subsurface  drainage,  should have sufficient phos-
phorus to  support algal  blooms [8].   Of course, in  many streams,  runoff
from  forested  areas  containing  very low concentrations of  phosphorus
dilutes  the drainage water from croplands [8],  and  in some cases, sedi-
ments eroded from stream banks and nonfertilized soils act as  phosphorus
sorbing  agents to reduce the soluble inorganic  phosphorus in  the  stream
[61, 62].


The  optimal  plans  for  a slow rate system should  involve (Da  forage
crop that removes large amounts of phosphorus, (2) erosion prevention to
eliminate  surface runoff, and (3) a  long pathway consisting of sorptive
materials  between  the  surface  soil  and the point of discharge  of  the
water  so  that  concentrations of phosphorus are reduced to low levels,
depending on the intended use of the  water.   A sufficient pathway  length
might  be  6 ft (2 in) in clayey soils,  but greater lengths should  be  re-
quired for sandy or silty soils.
     B.3.2  Rapid Infiltration Systems
Rapid  infiltration  systems,  as describee in Section 2.3,  are those  in
which  the  wastewater  is applied at annual  rates of 20 to  560 ft (6  to
170 m), and weekly rates of 4 to 120 in. (10  to 300 cm).  Vegetation may
be  grown  on  the surface of the basins, but since the typical  applica-
tions range  from  550  to 15 000 Ib/acre (616 to 16 800 kg/ha)  of phos-
phorus, at a concentration of 10 mg/L, the crop uptake is not a signifi-
cant part  of the phosphorus budget.  The removal  mechanisms of interest
are based on the sorption capacities of the soil.   The chemical  composi-
tion of  the wastewater is also important because the compounds of iron,
calcium,  and  aluminum, and pH are important in precipitating the phos-
phorus from soil solution.
breenberg  and  Thomas  reported phosphorus retention by a  Hanford  sandy
loam  during  a rapid infiltration system in which water application  was
about 0.5 ft/d (0.6 m/d) [63].  The phosphorus concentration was  about 2
to  3  mg/L  in  the  final   effluent  added to the infiltration  basins.
During  about  2 years of operation, all  of the phosphorus  added  was  re-
tained in the surface foot of soil.  The  calcium and bicarbonate  concen-
trations in  the  water  were sufficiently high that the soil  would have
become alkaline, and phosphorus sorbed could have been largely converted
to calcium phosphates.
                                  B-13

-------
                        FIGURE B-3

       RELATIONSHIP AMONG PHOSPHORUS  CONCENTRATION,
        DRAINAGE FLOW, AND THE AMOUNT OF  PHOSPHORUS
               TRANSFER FROM LAND TO  STREAMS
1.2 i-
i.o h
0.8
0.6
0.4
0,2
    0          5         10         15

                 DRAINAGE,  in./yr

  1  Ib/acre • yr- 1.12 kg/ha   yr

  1  in./yr- 2.54 cm/y r
                                          PHOSPHORUS  TRANSFER
                                               TO STREAMS,
                                               Ib/acre-yr
                                                   1.0
                            B-14

-------
Perhaps  the  most definitive report on phosphorus in rapid infiltration
systems  has  been  done  in  the Flushing Meadows project [1, 64].   The
phosphorus  concentration in the wastewater averaged 15 mg/L in 1969 but
decreased  to  about  10  mg/L  for the 1970 to 1972 period.  Phosphorus
removal  was  increased  with  an  increase in travel distance which was
related  to time.  A travel distance of 30 ft (9 m) removed about 70% of
the  phosphorus  in  1969.  The removal was reduced to about 30% in  1970
because  of  a substantial increase in flowrate, and it was increased to
50%  in  1972.   With  a flow distance of 330 ft (100 m), the phosphorus
ranoval  was  about 90%.  The effluent at this distance had a phosphorus
concentration less  than 1 to 3 mg/L in the 1971 to 1972 period, and the
reduction  was  greater  with  an  even longer travel distance.  After 5
years  of operation  of  this system and  phosphorus additions of nearly
43 000 Ib/acre (48 000 kg/ha), the removal efficiency was rather stable.
The  phosphorus  removal mechanism in this coarse gravelly soil was  pre-
cipitation of calcium phosphates.


The  phosphorus  removal  in  the  Flushing  Meadows project is entirely
satisfactory  for  reuse  of  water  for  irrigating crops even at short
travel  distances.   The removal to the level (less than 0.03 mg/L) where
phosphorus  would  limit  biological production in lakes is not definite
in  this  rapid  infiltration  system  at  the high rates with this  soil
material.   Perhaps,  with  time for attainment of an equilibration  with
hydroxyapatite  at  high  calcium concentrations and alkaline pH values,
this  concentration  would  be  obtained,  but  the required time is not
known.
Rapid  infiltration systems naturally require coarse gravelly soils that
can  sustain high infiltration rates at the surface and also high trans-
mi ssivity from  the point of infiltration to the point of discharge into
surface  waters  or  into  wells.   This  means that no layers with high
sorptive  capacity  for  phosphorus  are likely to be encountered.  What
little  capacity there is will soon be saturated, and the retention will
then depend on precipitation reactions.  The most logical precipitant is
the  calcium  supply in the wastewater.  If that supply is insufficient,
application  of  a  calcium supply may be considered if removal  of phos-
phorus is deemed to be necessary for future uses of the waters.


Rapid  infiltration systems naturally use a cycle of flooding and drying
to  maintain the infiltration capacity of the soil  material, and in some
cases,  to  control  insect pests in surface applied waters.  Therefore,
these rapid infiltration systems can be considered to use flooded soils.
These  cycles  of  reduction  and  oxidation can increase the phosphorus
retention  capacity  of  the soil if considerable iron is present in the
soil  or  in  the  wastewater.   Reduction during flooding and oxidation
during drying increase the reactivity of the sesquioxide fraction of the
soil,  increase the phosphorus sorbed, and decrease the phosphorus solu-
oility [65].  Of course, most rapid infiltration systems will use coarse
gravelly  soils  for  which  the calcium phosphate chemistry will be the
                                  B-15

-------
critical  factor;  iron  and aluminum will  have minor effects because  of
the very low surface area of the soil  material  and the limited number  of
sorption sites on iron and aluminum surfaces will  soon become saturated.


     B.3.3  Overland Flow Systems
Overland  flow systems are used where the  soil  is  slightly  permeable  and
treatment  occurs by biological, chemical,  and  physical  reactions  on  the
soil  surface  (Section 2.4).  A large portion  of  the  applied  wastewater
is  collected  as  treated  runoff  at  the toe of the slope.   Since  the
wastewater  flow  is predominately on the  soil  surface,  the soil contact
is less than for slow rate and rapid infiltration  systems.   As such,  the
phosphorus  removal  may be less for overland flow  systems,  although com-
binations can  be  used to achieve treatment alternatives (Section 3.3).
The usual reductions in phosphorus concentrations  in the wastewater have
been  35 to 60% with overland flow systems  [67-69].  Thomas et al. found
that the phosphorus concentration was reduced from 10  to about 5 mg/L of
total  phosphorus in an overland flow system [69].   However, applications
of  aluminum  sulfate  at  a  concentration of  20  mg/L to the  wastewater
reduced  the  phosphorus  concentration of the treated  water to about
1  mg/L for a 90% removal of the total  phosphorus input.
Data  from  Carlson  et  al.   show that the  phosphorus  concentration  de-
creased at  a  fairly  uniform rate as wastewater ran over overland flow
plots  [70].   The phosphorus concentration  in  the effluent water was 40
to  60%  of  that  in the applied water.   However, water  that percolated
through  the  soil had only  traces of phosphorus  for nearly complete  re-
moval.  The harvested grasses removed less than 10% of  the applied phos-
phorus.  The  recommendation for more effective removal of phosphorus in
the  overland flow effluent  was to obtain  more  contact  between the water
and soil  surfaces by increased soil  roughness or  by increased flow path.
     B.3.4  Wetland Systems
Although  wetland  systems have only been  studied  recently  as  a  means  of
wastewater  treatment,  the  principles  behind  phosphorus behavior  under
such  conditions  are  known.  Sufficient  research has  been completed  on
flooded rice culture that the behavior of  phosphorus  in flooded  soils  is
fairly  well  understood.   Also,  recent reports have added considerable
information on the chemistry of phosphorus in lake sediments.


When  soils  are flooded with a few feet of water, biological  activities
in the soil deplete the available  oxygen,  and the  soil  becomes anaerobic
or,  more  specifically,  anoxic  (lack  of oxygen).  The  water usually
remains  aerobic,  and  a  transition zone between aerobic  and anaerobic
conditions  develops  in the immediate surface  of  the soil. The surface
ot  this  transition zone is aerobic and oxidized, whereas  the bottom  is
                                  B-16

-------
anaerobic and reduced.  The thickness of the oxidized part of this tran-
sition layer  can vary from about 0.1 to 1  in.  (0.25 to 2.5 cm)  or more,
depending, on the rate of supply of oxygen to the surface of the  soil  and
the  rate  of  consumption  of oxygen in the lower soil depths [65],   In
wetland  situations where there is seasonal  flooding followed by drying,
such  as  in  rice  production, the soil goes through seasonal or yearly
cycles  of reduction and oxidation that result from cycles of anoxic  and
oxic  conditions.   Even in wetlands that are not seasonally flooded  but
are  wet  because of cycles of inputs of water, alternate periods of  re-
duction and  oxidation  occur  to  some degree.  Thus, one feature asso-
ciated with  all  types  of  wetlands  is the occurrence of reduced con-
ditions or cycles of reduction and oxidation.


When soils and sediments become anoxic, most show an increase in soluble
phosphorus  [65,  71-73].  This increase in soluble phosphorus was found
to  be  greatest  with  alkaline soils and with soils that have  low iron
contents,  and  it was found to be lowest with acid soils with high iron
contents [71].  Some acid soils with high iron contents show no  increase
or  decrease  in  soluble  phosphorus  as  reducing  conditions  develop.
Patrick and Mahapatra stated that the possible mechanisms for release of
soluble  phosphorus  principally involved the reduction of iron  from  the
ferric  to  the  ferrous  state with a release of phosphorus from ferric
phosphates  and the hydrolysis of iron and aluminum phosphates [65].   In
soils  with  large  amounts of iron oxide and iron hydroxide surfaces or
aluminum oxides, the net result of reduction is a decrease in phosphorus
solubility  because  of  secondary  precipitation of the dissolved phos-
phorus" on surfaces that become more reactive when the soil is reduced.

When phosphorus is added to soils and sediments, the effect of reduction
is  to  increase  phosphorus  sorption as compared to the oxidized state
[65,  73].   Khalid et al. found a significant correlation between phos-
phorus sorbed  under  reduced  conditions  and  the  iron  extracted   by
oxalate,  also  under  reduced  conditions.  They postulated that poorly
crystallized  and amorphous oxides and hydroxides of iron play a primary
role  in  phosphorus  retention  in  flooded  soils  and sediments [73].
Bortelson  and  Lee  concluded from studies of lake sediments that iron,
manganese,  and  phosphorus are closely related in their deposition pat-
terns and  that iron content appeared to be the dominant factor  in phos-
phorus retention  [74].   Williams  et  al.  [75] and Shukla et  al. [76]
found  that  noncalcareous  sediments  sorbed  more phosphorus than cal-
careous sediments.  Shukla et al. reported that the oxalate treatment of
lake  sediments to remove iron and aluminum almost completely eliminated
the ability of sediments to retain phosphorus [76].  The amounts of iron
removed  were  much  greater  than  the  amounts  of aluminum removed by
oxalate.   They suggested that a gel complex of hydrated iron containing
small  amounts  of aluminum oxide, silicon hydroxide, and organic matter
was  the  major  phosphorus-sorbing component in sediments under reduced
conditions.   Norvell  found  that  sediments,  maintained under  reducing
conditions,  sorbed  phosphorus at temperatures of 39 to 41°F (4 to 5°C)
and  that  calcium, iron, and manganese were lost from both exchangeable
and soluble forms during phosphorus sorption [77].
                                  B-17

-------
The  retention of phosphorus by sediments in aqueous suspension has been
demonstrated  adequately.   Thus,  the  problem  of  getting  phosphorus
retention  by  soils  and sediments is no greater than in aerated soils.
But  the  problem of getting contact between the sediments and soils and
the  wastewater  represents  a serious limitation.  Pomeroy et al.  found
evidence  of  significant  exchange  of phosphorus between sediments and
water when the sediments were suspended in the water, but when they were
separated  the  exchange  was trivial  [78].   Where the sediments are not
suspended,  only  a thin layer at the boundary between the water and the
sediments is active in phosphorus retention.  When wastewaters are  added
to  wetlands,  the  sediments  can play a significant part in removal  of
phosphorus  from  the  water  only  if the water moves in and out of the
sediments,  or  if  wind  or  wave action keeps the sediments suspended.
Running wastewater slowly over flooded soils in which plants are growing
might be expected to remove phosphorus in a similar manner, and to  about
the same extent as found in overland flow systems, but in both cases the
capacity  of  soil   and sediments to reduce phosphorus concentrations is
not fully used.


Spangler et al., after a 4 year study of natural  and artificial  marshes,
concluded that  these  had  potential  for wastewater treatment [79].  In
relation to phosphorus in a natural  marsh, they found that (1) the  marsh
ranoved  phosphorus  during  the  summer  and  released  it during  other
seasons, thus acting as a buffer; (2)  harvesting of marsh vegetation was
not  a  potential   for removing a large portion of the phosphorus input;
and  (3) passage  of  wastewater through 6 232 ft (1 900 m) of the  marsh
reduced the orthophosphate and total  phosphorus by 13% or less.   Some of
this  reduction  was  probably a result of dilution with other water.   A
mass balance, using estimated water flows and concentrations, showed the
same  order of magnitude of phosphorus leaving the marsh as entering it.
In other words, the marsh acted as a buffer for phosphorus concentration
but was not effective in reducing the output.
However,  Spangler  et al.  found that,  in contrast to the natural  marsh,
artificial   marshes  removed 84% of the phosphorus input into greenhouse
installations and 64% of the input into marshes constructed in the field
[79].   They  predicted that the removal  in the field would be 80% under
optimum  conditions.   Recommendations   were for a system in which water
would  flow through, rather than over,  the soil  in the artificial  marsh,
which   would   be  highly   significant  in  removal   of  phosphorus   as
demonstrated by the work of Pomeroy et  al. [78].
                                 B-18

-------
B.4  Models


     B.4.1  Background


In  a  model  that would be adequate for predicting the life of a waste-
water treatment system, based on phosphorus retention in soils and sedi-
ments, many factors should be considered, including:

     1.   The rate of application of phosphorus

     2.   The  amounts  of calcium, iron, and aluminum in the wastewater
          and  the  influence  of  these constituents on the sorption of
          phosphorus in the soil

     3.   The  removal  of  phosphorus by plant roots if the model  deals
          with  time  intervals  of  days or weeks, or annual removal of
          phosphorus  in harvested crops if the time intervals are years
          or decades

     4.   The travel distance and transit time of water flow

     5.   The transit time for water to move through the system relative
          to the kinetics of phosphorus sorption in soils and sediments

     6.   The rate of phosphorus application to the land relative to tne
          kinetics  of  phosphorus  reactions  with  soils (rapid infil-
          tration systems  might move phosphorus through before the slow
          reactions  have  an  effect oh phosphorus concentration in the
          flowing water)

     7.   Capacities and kinetics of sorption of phosphorus in soils and
          sediments  from  land  surface  to the point of discharge into
          ground or surface waters
Such  a  model  would  obviously be a three-dimensional model  that would
require  information  on  water  flow  and  phosphorus reactions that is
usually  not  available  and  not  easily obtained.  Most water flow and
proposed  models  for  phosphorus  retention  deal  only with flow in one
direction,  although  some  work, such as that reported by Jury [80, 81]
deals  with  two-dimensional water flow.  Thus, the discussion here will
deal with flow downward through soils and to a depth that can be sampled
and  studied  at reasonable cost.  This depth is perhaps 6 to 10 ft (1.8
to 3 m) in most cases but might be much deeper in cases of deep alluvial
material s.


All  models  are based on a materials balance, i.e., the phosphorus that
goes  into a volume of soil must be sorbed into the solid phase, must be
                                  B-19

-------
removed by  plants,  or must move through  the  soil  volume in  percolating
water.   This  means  that  all  models  have  a  water flow component  and  a
phosphorus  reaction  component,  and,   of  course, in  systems  involving
crops, plant removal is a third  component  for  both  water and  phosphorus.
Models  can  consist  of  simple  bookkeeping   for   water and phosphorus
balances  or  of  mathematical   equations  of  various degrees of  sophis-
tication.
     B.4.2  Limitations of Models
Although  progress  has  been  made  during   the   past  few years  in  the
development  of  models  of  phosphorus   movement  in  soils,  a  number of
problems  need to be solved before mathematical models or any other pre-
dictive models  can be used with any degree  of  accuracy [10,  39, 40,  46,
82-84].   Large  spatial   and temporal variability in  the hydraulic con-
ductivity of  soils  in  the  field  is   tremendous and  brings   up  the
questions  of  how  many  and  what kinds of samples or measurements  are
needed  to  characterize  the  water flow over  an area for a  given time.
After  the  data  are obtained, there are some  problems of averaging  and
interpreting such large variations [85,  86],
There  have  been  no  studies of the numbers  of  samples  needed  to  char-
acterize the phosphorus sorption properties  of a  field to a  given depth.
Most  sampling  studies have dealt with  problems  of estimating the  level
of  nutrients  in  the  plow  layer  of   soils.    Recent  studies of soil
sampling  for estimating the concentrations  of soluble salts and nitrate
in the unsaturated zone (to depths of lb to  20 ft or 4.5  to  6 m) suggest
that large numbers of samples are required and that adequate sampling  of
a  field  cannot  be  planned until  some knowledge of the variability  is
obtained [87, 88].  Similar information  on phosphorus sorption is needed
before models can be accurately applied  to fields, even if other limita-
tions to the models are removed.
The   composition  of  the  wastewater  (i.e.,   concentration   of   iron,
aluminum,  and  calcium)   will   have  an  influence  on  the   phosphorus
reactions  in  the soil  and the reactions  of wastewaters  that  acidify or
alkalinize  the  soil;   for  example,   the influence  of bicarbonate on
neutralizing  soil  acidity  will   have effects  on phosphorus  reactions.
Until  these  effects  become  inputs   into a  reliable  model,  the  proper
procedure  would be to  test each possible  soil with the wastewater,  or  a
reasonable simulation of the wastewater, being considered.
Perhaps  the  most serious limitation to  all  models is  that the  reaction
of  phosphorus  with  the  soil  cannot be predicted from measurements  of
simple  soil  properties  that  can  be  mapped  in the  field or  measured
quickly in the laboratory [46, 89].  Methods  of  characterizing  soil  that
might  correlate  with  phosphorus retention  are likely to be more time-
consuming than direct measurements of phosphorus sorption.
                                B-20

-------
To allow near maximum application rates, rapid infiltration systems will
require  coarse  gravelly  or  sandy soils having generally low sorptive
capacities.   These may soon be saturated, and the retention by the soil
system  ,wil.l  depend  mostly  on  the iron, aluminum, and calcium in the
wastewater  and  not  on the original soil material.   Exceptions to this
general  statement might include the use of calcareous sands and gravels
for  rapid  infiltration systems.  Plant removal  is usually too small  to
be  significant  in rapid infiltration systems.  Thus, the need is for a
model   that  considers  the constituents in the wastewater and how these
will  react  during flow through the soil  and sediments as a function of
distance of flow and rate of flow.
     B.4.3  Models of Kinetics of Phosphorus Reactions


The  mathematical  model for one-dimensional  phosphorus movement in soils
has  been  expressed in a number of ways.  Enfield et al .  [46] expressed
it as
where  C =     concentration of phosphorus in solution, mg/L
       D =     dispersion coefficient at velocity V, cm/h
       t =     time, h
      V =     average pore-water velocity, cm/h
       X =     distance from beginning of 3 flow path, cm
       P =     bulk density of soil, g/cm
       0 =     volumetric water content in the soil
       S =     sorbed phosphorus in solid phase, fig/g


The  first two expressions in the equation deal with water flow, and the
third  deals  with  the  retention  of phosphorus by the soil (i.e., the
kinetics  of phosphorus reactions),  before this equation becomes a use-
ful model, the kinetics of phosphorus reactions must be known.
The  kinetics  of  phosphorus  reactions  in soils has been studied by a
number of researchers [10, 33-36, 40, 47, 82, 90, 91].  Perhaps the most
definitive  study  was that of Enfield et al. who measured the reactions
of  phosphorus  in  25 soils for a period of 2 to 18 weeks, depending on
the  soil, and then used the data to test five kinetic models [46].  All
kinetic  models  agreed adequately with the experimental models.  Corre-
lation coefficients  between  predicted  values  and experimental  values
averaged  0.81 to 0.88, but these were averages of values for individual
soils.  That is, coefficients for each kinetic model were calculated for
and  unique  to  individual'  soils, so that to use the models, the phos-
phorus reactions  must  be  measured  to supply the coefficients for the
model for any individal soil material.
                                 B-21

-------
However,  Enfield  and  Shew  [40],  using  two  of the models tested by
Enfield et al.  [45], found good agreement between the predicted movement
of  phosphorus   and values experimentally determined in small  laboratory
columns which were fed a solution containing 10 mg/L of phosphorus.   The
first model was
  = a  (KC - S)
                                                           (B-4)
where    C = concentration of phosphorus, mg/L
         S = concentration of sorbed phosphorus, /xg P/g of soil
         t = time, h
 and, a, K = constants that depend on the soil
The second model was
f
                                                           (B-5)
where  the  symbols  have the same meaning as  before and a, b, and d are
constants  that  depend  on the soil.   Solutions to these equations were
provided,  and constants were calculated for two soils.   Combinations of
these  with water flow data predicted  phosphorus breakthrough curves for
the  two  soils  studied  over  a  period of several days.   Breakthrough
curves  indicated  that  the  boundary between saturated and unsaturated
soil  (enriched versus nonenriched) was diffuse as illustrated in Figure
B-l ,  so  that the concentration of phosphorus in the effluent increased
very slowly as the effluent volume increased.
Novak et al .  developed a theoretical  model  for movement of phosphorus in
soils  in  which the phosphorus sorption factor of Equation B-3 was cal-
culated from  existing  adsorption-desorption models developed for chro-
matography and  ion-exchange  processes  [82].   This  model  predicts an
abrupt  boundary  for  breakthrough of soluble phosphorus into any given
layer of soil .
Harter and Foster developed an empirical  model  which describes the move-
ment of  phosphorus  in  soils [83].   In  this approach, a soil sample is
repeatedly  treated  with  a solution of  known  phosphorus concentration,
and  the  sorbed  phosphorus  is  determined.  The relationship  between
                                 B-22

-------
phosphorus sorbed and the volume of solution that has contacted the soil
is then expressed as a polynomial adsorption equation


                         Y = A + BX + CX2 + DX3     .     (B-6)

where  Y  is  the  phosphorus  adsorbed,  X  is the amount of phosphorus
added,  and A, B, C, D are constants that depend on the soil.  From this
relationship,  the  phosphorus  breakthrough  curves,  or the phosphorus
leaching front, can be plotted against depth or  volume  of   wastewater
added.  The model is simple and might be adequate for most purposes, but
there are no  data available showing the effectiveness of  the  approach
in predicting field data.
Shah  et  al.  developed  a  materials  balance mathematical model  which
agreed  well with field data obtained from the barriered landscape  water
renovation  system  used to treat liquid swine manure [84].  The kinetic
equation in this model was based on the Langmuir adsorption equation.


     B.4.4  Empirical Model for a Slow Rate System
There  are  no  models that adequately describe all factors in water and
phosphorus  movement  in  field  soils  receiving municipal wastewaters.
Also,  there is not sufficient knowledge of phosphorus reaction kinetics
to  predict  the  sorption  of  phosphorus  in  a  field over periods of
decades.   Thus, the model presented here as Figure B-4 provides only an
empirical assessment of relative phosphorus retentions by soil profiles.


In  .this simple model, the phosphorus added minus the phosphorus removed
in  harvested  crops (Figure B-l) is assumed to react progressively with
successive  depth  increments  in  the  soil.  The first depth increment
becomes "saturated" before phosphorus moves to the next depth increment,
and  the  boundary  between  the  phosphorus-enriched  soil and the non-
enriched soil  is  assumed  to  be  rather abrupt, as in the theoretical
model  of  Novak  et  al. [82].  The term "saturated" is defined for the
purposes  of  this model as the soil in which enrichment with phosphorus
has  been  sufficient  that  movement with percolating water is signifi-
cantly above  background  for the original soil material.  Also, in this
model, (1) water movement is considered to be so unimportant relative to
phosphorus reactions that it can be disregarded, (2) there is sufficient
time  for  slow phosphorus reactions to have a large impact, and (3) the
phosphorus sorption capacities for the depth increments include the slow
reactions.
The  sorption capacities for the soil horizons used in Figure B-4  were
taken from a study by Enfield and Bledsoe [10] in which 10 grams of soil
were  treated  with  100  ml  of  solution  containing a phosphorus con-
centration  of  10  mg/L.   The  reaction  time  in  this study was only
                                  B-23

-------
                               FIGURE  B-4

            ILLUSTRATION OF  A SIMPLE PHOSPHORUS BALANCE-
          PHOSPHORUS REACTION MODEL  FOR A SLOW RATE  SYSTEM
  PHOSPHORUS
  APPLIED  IN
  WASTEWATER,
150  Ib/aere-yr
  PHOSPHORUS
  REMOVAL IN
  HARVESTED
    CROPS,
50 Ib/aere-yr
          PHOSPHORUS
      SORPTION  CAPACITY,
        lb/acre-6  in.
    NOTE:  THE PHOSPHORUS SORPTION CAPACITIES  USED
          •ERE DOUBLE THE SORPTION MEASURED IN A
          125 DAY REACTION PERIOD IN THE  LABORATORY.


          1  lb/acre>yr= 1.12  kg/ha>yr
                                   B-24

-------
125  days;  consequently,  the  sorption   capacities  in  the  Enfield  and
Bledsoe   study were doubled to adjust  for slow  reactions  that   continue
for indefinite periods in most soils.


This model, expressed mathematically,  is


                               T -   $P                    (B-7)

                                   'p  - HP
where  T =     time  for  the phosphorus front to reach a given depth in
               the soil, yr
      S  =     the  sorption  capacity  of the volume of soil above that
       p       depth, Ib/acre (kg/ha)
               the input phosphorus, lb/acre-yr (kg/ha-yr)
               the  phosphorus  removed  in  harvested crops, lb/acre-yr
               (kg/ha-yr)
The uncertainties in the model  are in the measurements of the phosphorus
sorptive  capacity  and the assumed abrupt boundary between enriched and
nonenriched soil.  There is reason to believe that the phosphorus reten-
tion characteristics of a soil  cannot be adequately characterized in the
laboratory  in  a  fixed  period of time.  Also, there is ample evidence
from  fields  that  have  received  large  amounts of phosphorus as fer-
tilizers or as wastes that the soluble phosphorus gradually decreases as
a  function  of  depth  with  a  diffuse  rather than an abrupt boundary
between  the  highly  enriched and the nonenriched soil  horizons [5, 19,
49, 51, 52, 93].  But, perhaps even considering these uncertainties, the
model   can  be useful as a preliminary estimate of the phosphorus reten-
tion characteristics of various soils and sediments.  This type of model
is  implied  in  the rate classes proposed by Schneider and Erickson for
phosphorus sorption measurements in soils as a limitation for the use of
the  soil  for  treating  municipal  wastewaters [94].  Their limitation
classes  ranged  from  very high to very low, respectively, as the phos-
phorus sorption  increased  from  less  than  1 QUO  to  more than 2 000
Ib/acre (1 120 to 2 240 kg/ha)  in 3 ft (0.9 m) of soil.
If  a  model  such  as presented in  Figure B-4 is  used to classify the
desirability   of  various  potential  areas  for  a  given  wastewater,
monitoring  of  the phosphorus movement in the site selected can be used
to revise estimates of the longevity of the site as it is being used.


     B.4.5  Model for Rapid Infiltration Systems


At  the  present  time,  there is no accepted model that can predict the
movement  of  phosphorus  through  soil  profiles.   But,  one promising
approach  which  considers the rate of reaction of phosphorus with soils
is  that of Enfield and Bledsoe [10]; Enfield and Shew [40], and Enfield
[39,  95].  In this approach, solutions containing phosphorus at various
                                B-25

-------
concentrations were  reacted  with soils for up to 125 days,  using batch
techniques.   The  sorption  aata thus obtained were compared with phos-
phorus breakthrough curves using small 1.9 in.  (5 cm)  long soil  columns.
As might be expected from discussions of reaction kinetics of phosphorus
in  soils,  the  sorption of phosphorus obtained from a 10 hour reaction
period  seriously  underestimated the amount of phosphorus sorbed by the
columns  in 55 days.  However, sorption curves  had been obtained at time
intervals  from 1 to 3 000 hours, approximating a geometric progression,
so that sorption surfaces as a function of (1)  equilibrium solution con-
centration, (2) amount  of  phosphorus sorbed by the soil, and (3) time,
were  produced for each soil.  When these sorption surfaces were used to
adjust   the   ratio   of  phosphorus  sorbed  to  equilibrium  solution
concentration  for  time  corresponding  to time intervals in the break-
through curves, there was a markea increase in  the agreement between the
batch and column techniques.
The  sorption surfaces were used to calculate  the sink term 8S/3t in  the
equation


                          9C _  TT 8C   e 8S                   /R p\
                            --V-                        (B'8)
where  £ =     solution phase concentration of  phosphorus,  mg/L
       V" =     average pore-water velocity, in./h (cm/h)
       X =     distance from the beginning  of^tne flow path,  in.  (cm)
       e =     bulk density of the soil,  g/cm
       6 -     volumetric water content of  the  soil
       S =     solid phase concentration  of sorbed phosphorus, M9/9
       t =     time, h

and the sink term was calculated from

                              || - a CbSd                    (B-9)
where  a,  b,  and  d  are  constants  and C,  S  and t are as defined for
Equation  B-B.   Using  these  equations,  the  breakthrough curves agreed
well with predicted curves in three of four soils.


Enfielu recognized that this approach was  not  satisfactory for all  soils
and  that  it did not predict the effects  of rest periods and desorption
of  phosphorus  during  rains  and the resultant leaching with rainwater
[95].  Nevertheless, this approach gives an adequate first approximation
to the transport of phosphorus through soils and can provide a basis for
design  of  wastewater  treatment  systems. Enfield recommended that an
average  phosphorus  concentration or application rate adjusted for rest
periods, plant removals, and rainwater, be used  [95].
                                   B-26

-------
There  are some serious questions about this approach that must be  added
as  words  of  caution.  The spatial  variability  in phosphorus  reactions
and  in water flow can be much smaller in the laboratory columns *than  in
the  field.  Temperature effects on the kinetics  of phosphorus  reactions
are not built into the laboratory studies but will  be encountered in the
field.   In the field, a given volume of soil  will  react with  increasing
concentrations  of  phosphorus  as  a function of time of treatment with
wastewater;  whereas,  in the sorption measurements presented  by Enfield
and  Bledsoe  [1U],  the  soil reacted with decreasing concentrations  of
phosphorus.   Solutions of phosphorus at 10, 40,  and 100 mg/L were  added
to soils and the decrease in concentration was measured as a function  of
time  which is an approach to equilibrium from the opposite direction  as
in  the  field.   The  sink  term, 9S/3t,  of Equation B-8 might be sub-
stantially different under these two conditions in some soils.
Another  aspect concerning this approach is more pragmatic.   Considering
the status of such models, it may be no more expensive to set up  columns
of  soils  in  the  laboratory  and treat them with  the wastewater  for  a
period of 4 to 6 months and directly measure the movement of phosphorus.
B.5  References
 1.  Bouwer,  H.  and  R.L.  Chaney.    Land   Treatment  of
     Advances in Agronomy.  26:133-176,   1974.
                                          Wastewater.
 2.  Pound,   C.E.  and  R.W.    Crites.    Characteristics   of   Municipal
     Effluents.  In:  Recycling Municipal  Sludges and Effluents on  Land.
     Washington,  D.C.,  National   Association of State Universities  and
     Land Grant Colleges. 1973.  pp.  49-61.

 3.  Hunter,  J.V. and T.A. Kotalik.   Chemical  and Biological  Quality of
     Treated  Sewage   Effluents.     In:    Recycling   Treated   Municipal
     Wastewater  and  Sludge  Through Forest and Cropland.   Sopper, W.E.
     and  L.T.  Kardos   (ed.).   University  Park,  Pennsylvania   State
     University Press.  1976.  pp.  6-25.

 4.  Thomas,  R.E.   Fate of Materials Applied.  In:   Proceedings of  the
     Conference  on  Land  Disposal   Municipal   Effluents  SIudges.  EPA-
     902/9-73-001. 1973.  pp.  181-200.

 5.  Russel,  E.W.   Soil  Conditions and  Plant Growth.  London, Longman
     Group Limited.  1973.  Tenth  edition,  p.  849.
 6.  Larson,  S.
     1967.
Soil  Phosphorus.  Advances in Agronomy.   19:151-210,
 7.   Tisdale,  S.L.  and  W.L.   Nelson.   Soil  Fertility and Fertilizers.
     New  York,  Macmillan  Publishing  Co.,  Inc.   1975.   Third edition.
     694 p.
                                   B-27

-------
 8.  Holt,  R.F.,  D.R.   Timmons,   and  J.J.  Latterell.   Accumulation  of
     Ph'osphate in Water.   J.  Agri.  Food Chem.   18:781-784,  1970.

 9.  Ryden, J.C., J.K.  Syers, and R.F. Harris.   Phosphorus  in  Runoff and
     Streams.  Advances  in Agronomy.  25:1-41,  1973.

10.  Enfield,  C.G.   and  B.E. Bledsoe.  Kinetic  Model  for Orthophosphate
     Reactions  in  Mineral  Soils.   EPA-660/2-75-022.  Washington,  D.C.,
     U.S. Government Printing Office.  June 1975.

11.  Blanchar, R.W.  and  L.R.  Hossner. Hydrolysis and  Sorption  of  Ortho-,
     Pyro-, Tripoly-, and Trimetaphosphate  in 32 Midwestern Soils.  Soil
     Sci. Soc. Amer. Proc.  33:622-625, 1969.

12.  Murrrnan,  R.P.   and  F.R. Koutz.  Role  of Soil  Chemical  Processes  in
     Reclamation  of  Wastewater Applied   to   Land.     In:    Wastewater
     Management by Disposal  on Land.  Corps of  Engineers, U.S.  Army Cold
     Regions Research and Engineering Laboratory,  Hanover,  N.H.   1972.

13.  Ellis,  B.G.   The   Soil  as   a  Chemical   Filter.   In:   Recycling
     Municipal  Wastewater  and Sludge  Through  Forest and   Cropland.
     Sopper, W.E. and L.T. Kardos  (eds.).   University Park,  Pennsylvania
     State University Press.   1973.  pp. 46-70.

14.  Lindsay,  W.L.    Inorganic Reactions  of  Sewage Wastes With Soils.
     In:    Recycling   Municipal    Sludges   and  Effluents  on    Land.
     Washington,  D.C.,   National   Association  of State  Universities and
     Land Grant Colleges.  1973.

15.  01 sen,  S.R.   Micronutrient   Interactions.  In:  Micronutrients  in
     Agriculture.   Mortvedt,  J.J.,  P.M.  Giordano,  and   W.L.  Lindsay
     (eds.).  Madison,  Soil  Sci. Soc. Amer.,  Inc.   1972.

16.  Bingham, F.T.  Phosphorus.  In:  Diagnostic Criteria for  Plants and
     Soils.   Chapman,   H.D.   (ed.).  University of California, Division
     of Agricultural Sciences.  1966.

17.  Baker,  D.E.  and  L.  Chesnin.   Chemical   Monitoring of Soils for
     Environmental  Quality  and Animal  and Human Health. Advances  in
     Agronomy.  27:305-374, 1975.

18.  Agricultural  Waste   Management Field  Manual.   U.S.  Department  of
     Agriculture, Soil  Conservation Service.  August  1975.

19.  Kardos,  L.T. and J.E. Hook.   Phosphorus Balance in Sewage Effluent
     Treated Soils.   Journal  of Environmental Quality.  5:87-90,  1976.

20.  Kutera, J.  Treatment and Disposal of  Wastewaters of Settlements  in
     Rural,  Agricultural  and  Non-Urban   Areas.    Progress   in  Water
     Technology.  7:877-884,  1975.

21.  01 sen,  S.R. and F.S. Watanabe.  A Method  to Determine a  Phosphorus
     Adsorption  Maximum  of Soils  as Measured  by the Langrnuir Isotherm.
     Soil Sci. Soc.  Amer. Proc. 21:144-149,  1957.
                                  B-28

-------
22.   Ellis,  B.G.   and  A.E.   Erickson.   Movement and Transformations  of
     Various  Phosphorus  Compounds  in  Soils.   Report to  Michigan  Water
     Resources Commission.  1969.

23.   Chang,  S.C.   and  M.L.  Jackson.  Fractionation of Soil  Phosphorus.
     Soil  Science.  84:133-144,  1957.

24.   Sabbarao,   Y.V.   and   R.   Ellis,   Jr.    Reaction  Products   of
     Polyphosphates  and  Orthophosphates  With   Soils  and on Uptake  of
     Phosphorus  by  Plants.    Soil  Sci.  Soc.  Amer.  Proc.   39:1065-1088,
     1975.

25.   Bell,   L.C.  and  C.A.  Black.    Crystal line Phosphates Produced  by
     Interaction  of  Orthophosphate  Fertilizers With Slightly Acid and
     Alkaline Soils.  Soil Sci.  Soc. Amer.  Proc.  34:735-740,  1970.

26.   Lindsay,  W.L.,  A.W. Frazier, and  H.F. Stephenson.  Identification
     of  Reaction  Products  From  Phosphate Fertilizers in Soils.   Soil
     Sci.  Soc. Amer. Proc.  26:446-452,  1962.

27.   Beaton,  J.U., T.L. Charlton, and R. Soper.  Identification of Soil
     Fertilizer  Reaction  Products in a Calcareous  Saskatchewan Soil  by
     Infrared Absorption Analysis.  Nature.  197:1329-1330, 1963.

28.   Racz,  G.J. and R.J. Soper.   Reaction Products of Orthophosphates  in
     Soils    Containing  Various  Amounts  of  Calcium  and   Magnesium.
     Canadian Journal of Soil Science.  47:223-230,  1967.

29.   Lindsay,  W.L.  and  E.G.  Moreno.    Phosphate   Phase Equilibria  in
     Soils. Soil Sci. Soc. Amer. Proc.  24:177-182,  1960.

30.   Taylor,  A.W.,  E.L.  Gurney,  and   E.G.   Moreno.  Precipitation  of
     Phosphate  From  Calcium  Phosphate  Solutions   by  Iron  Oxide and
     Aluminum Hydroxide. Soil Sci. Soc.  Amer.  Pro.  28:49-52,  1964.

31.   Taylor,  A.W.,  E.L.  Gurney,  and   A.W.  Frazier.  Precipitation  of
     Phosphate  From  Ammonium  Phosphate  Solutions  by  Iron Oxide and
     Aluminum Hydroxide. Soil Sci. Soc.  Amer.  Proc.   29:317-320, 1965.

32.   Fox,   R.L.  and  E.J. Kamprath.  Phosphate  Adsorption Isotherms for
     Evaluating  the  Phosphate   Requirements of  Soils.  Soil Sci.  Soc.
     Amer.  Proc.  34:902-9U6, 1970.

33.   Rajan,  S.S.S.  and  R.L.  Fox.  Phosphate  Adsorption by Soils.   I.
     Influence  of  Time  and Ionic Environment  on Phosphate Adsorption.
     Comm.   Soil Sci. Plant Anal.   3:493-504,  1972.

34.   Chen,   R.V.S.,  J.N.  Butler,  and   W.  Stumm.    Kinetic  Study   of
     Phosphate Reaction With Alminum Oxide  and Kaolinite.   Environmental
     Science and Technology.   7:327-332,  1973.

35.   Barrow,  N.J.  and  T.C. Shaw.  The Slow Reactions Between Soil and
     Anions.  Soil Science.  119:167-177, 1975.
                                    B-29

-------
36.  Carritt,  D.E.   and  S.    Goodgal.    Sorption  Reactions   and   Some
     Ecological  Implications.  Deep Sea  Research.   1:224-243,  ly54.

37.  Dean,    L.A.   and  E.J.   Rubins.  Anion  Exchange  in  Soils.   I.   Ex-
     changeable   Phosphorus  and   the  Anion   Exchange Capacity.    Soil
     Science.  63:377-387,  1947.

38.  Rennie,  D.A. and R.B. McKercher.   Adsorption of  Phosphorus by  Four
     Saskatchewan  Soils.   Canadian Journal  of Soil Science.   39:64-75,
     1959.

39.  Enfield,  C.G.   Rate of Phosphorus  Sorption by Five  Oklahoma Soils.
     Soil  Sci. Soc.  Amer. Proc.  38:404-407,  1974.

40.  Enfield,  C.G.   and  D.C.  Shew.   Comparison of Two  Predictive  Non-
     Equilibrium Models  for  Phosphorus  Sorption  and Movement Through
     Homogeneous  Soils.   Journal of  Environmental Quality.   4:198-202,
     1975.

41.  Coleman,  N.T.,  J.T.  Thorup, ana W.A.  Jackson.  Phosphate Sorption
     Reactions  That  Involve  Exchangeable   Al.  Soil Science.  90:1-7,
     1960.

42.  Fox,  R.L.  and E.J. Kainprath.  Adsorption and Leaching of P in  Acid
     Organic  Soils  and  High Organic Sand.   Soil Sci. Soc.  Amer.  Proc.
     35:154-156, 1971.

43.  Hayes, F.R., J.A. McCarter,  M.L.  Cameron, and D.A. Livingstone.  On
     the  Kinetics of Phosphorus  Exchange in Lakes. Journal  of Ecology.
     40:202-212, 1952.

44.  Haseman,  J.F.,  E.H.   Brown,  ana  C.U.  Whitt.   Some Reactions of
     Phosphate With Clays and Hydrous  Oxides of Iron and  Aluminum.   Soil
     Science.  70:257-271,  1950.

45.  McAuliffe,   C.D.,  N.S.   Hall,   L.A.  Dean,  and   C.B.  Hendricks.
     Exchange  Reactions  Between  Phosphates  and   Soils:   Hydrolytic
     Surfaces of Soil Minerals.  Soil  Sci. Soc. Amer.  Proc.  11:119-123,
     1947.

4o.  Enfield,  C.G.,  C.C.  Harlin, Jr.,  and  B.E. Bledsoe.  Comparison of
     Five  Kinetic Models for Orthophosphate Reactions in Mineral Soils.
     Soil  Sci. Soc. Amer. J.  40:243-249, 1976.

47.  Munns,  D.N. and R.L.  Fox.  The Slow Reaction Which  Continues  After
     Phosphate  Adsorption:   Kinetics  ana  Equilibrium in Some Tropical
     Soils.  Soil Sci. Soc. Amer. J.  40:46-51, 1976.

48.  Kao,  C.W.   and  R.W.   Blanchar.    Distribution  and  Chemistry  of
     Phosphorus  in  an  Albaqualf  Soil  After  82  Years  of Phosphate
     Fertilization.  Journal  of Environmental Quality.  2:237-240,  1973.
                                   B-30

-------
49.  DeHaan,  F.A.M.   Interaction-Mechanisms in Soil  as Related to Soil
     Pollution  and  Grounawater  Quality.  Institute for Land and Water
     Management   Research,  Wageningen,  The   Netherlands.   Technical
     Bulletin No. 95.  1976.

50.  Thomas,  R.E.   Land  Disposal.   II.   An  Overview  of  Treatment
     Methods.  Jour. WPCF.  45:1477-1484, 1973.

51.  Pratt,  P.P.,  W.W. Jones, and K.D. Chapman.  Changes in Phosphorus
     in an Irrigated Soil During 28 Years of Differential Fertilization.
     Soil Science.  82:295-306, 1956.

52.  Spencer,  W.F.  Distribution and Availability of Phosphate Added to
     Lakeland Fine Sand.  Soil  Sci. Soc. Amer. Proc.  21:141-144,  1957.

53.  Neller, J.R.  Mobility of Phosphate in Sandy Soils.  Soil  Sci. Soc.
     Amer. Proc.  (1946) 11:227-230, 1947.

54.  Larson,  J.E.,  R.  Langston,  and  G.F.  Warren.   Studies  on the
     Leaching of Applied Labeled Phosphorus in Organic Soils.  Soil Sci.
     Soc. Amer. Proc.  22:558-560, 1958.

55.  Larson,  V.,  J.H. Axley,  and G.L. Miller.  Agricultural Wastewater
     Accommodation  and  Utlization  of  Various Forages.  University of
     Maryland  Water  Resources  Research  Center,  College  Park,   Md.
     Technical  Report No. 19.  1974.

56.  Hook, J.E., L.T. Kardos, and W.E. Sopper.  Effects on Land Disposal
     of Wastewater on Soil Phosphorus Relations.  In:   Recycling Treated
     Municipal   Wastewater  and  Sludge  Through  Forest  and  Cropland.
     Sopper, W.E. and L.T. Kardos (eds.).  University Park, Pennsylvania
     State University Press.  1973.  pp. 200-219.

57.  Gburek,  J.W.  and W.R. Heald.  Soluble P Output of an Agricultural
     Watershed  in Pennsylvania.  Water Resources Research.  10:113-118,
     1974.

58.  Johnson,  A.H.,  D.R.  Boudlin,  E.A.  Goyette,  and  A.M.  Hodges.
     Phosphorus  Loss  by  Stream  Transport  From  a  Rural  Watershed:
     Quantities,  Processes  and   Sources.   Journal   of  Environmental
     Quality.  5:148-157, 1976.

59.  Baker,  J.L.,  K.L.  Campbell,  H.P.  Johnson,  and  J.J.   Hanway.
     Nitrate,  Phosphorus,  and  Sulfate  in Subsurface Drainage Waters.
     Journal of Environmental Quality.  4:406-412, 1975.

60.  Calvert,  D.V.   Nitrate,  Phosphate  and  Potassium  Movement Into
     Drainage  Lines  Under  Three  Soil Management Systems.  Journal of
     Environmental Quality.  4:183-186, 1975.

61.  Taylor,  A.W.  and  H.M.  Kunishi.  Phosphate Equilibrium in Stream
     Sediment  and  Soil in a Watershed Draining an Agricultural Region.
     J. Agri. Food Chem.  19:827-831, 1971.
                                  B-31

-------
62.  Kunishi,  H.M.  et  al.  Phosphate Movement From an Agricultural Water-
     shed During  Two Rainstorm Periods.  J. Agri. Food Chem. 20:900-905,
     1972.

63.  Greenberg,  A.E.   and J.F.  Thomas.  Sewage  Effluent  Reclamation  for
     Industrial  and   Agricultural   Use.    Sewage and  Industrial Wastes.
     26:761-770,  1954.

64.  Bouwer,  H., J.C. Lance,  and M.S. Riggs.  High Rate  Land  Treatment.
     II.   Water  Quality  and  Economic Aspects of the Flushing Meadows
     Project.   Jour.  WPCF.  46:844-859, 1974.

65.  Patrick,   W.H.,   Jr.,  and   I.C.   Mahapatra.   Transformation   and
     Availability  to   Rice  of   Nitrogen   and Phosphorus in Waterlogged
     Soils.  Advances  in Agronomy.   20:323-359,  1968.

66.  Seabrook,  b.L.    Land  Application   of  Wastewater   in   Australia.
     Environmental  Protection  Agency,  Office of  Water  Management Program
     Operations.   EPA-430/9-75-017.   1975.

67.  Kirby,  C.F.   Sewage  Treatment Farms.    (Postgraduate   course in
     Public  Health  Engineering).    University  of Melbourne,  Australia.
     Session No.  12,  Department  of Civil Engineering.  1971.   14 p.

68.  Law,  J.P.,   Jr.,  R.E. Thomas,  and L.H. Myers.   Cannery  Wastewater
     Treatment  by  High-Rate  Spray on Grassland.  Jour.  WPCF.  42:1621-
     1631,.1970.

69.  Thomas,  R.E., B. Bledsoe,  and K. Jackson.  Overland Flow Treatment
     of  Raw Wastewater With Enhanced Phosphorus Removal.  EPA-600/2-76-
     131.  June 1976.

70.  Carlson,   C.A.,   P.G.  Hunt,  and T.B. Delaney,  Jr.  Overland Flow
     Treatment   of   Wastewater.    U.S.   Army Engineering   Waterways
     Experiment  Station,  Vicksburg,  Miss.  Miscellaneous Paper Y-74-3.
     August 1974.

71.  Pannamperuma,  F.N.  The  Chemistry of Submerged Soils.  Advances in
     Agronomy.  24:29-96, 1972.

72.  Patrick,   W.H.,   Jr.,  and   R.A.  Khalid.   Phosphate Release   and
     Sorption   by  Soils and Sediments:  Effect  of Aerobic and Anaerobic
     Conditions.   Science.  186:53-55, 1974.

73.  Khalid,  R.A.,  W.H.  Patrick,   Jr.,   and R.D. Delaune.   Phosphorus
     Sorption  Characteristics  of Flooded Soils.  Soil  Sci. Soc. Amer. J.
     (submitted).  1976.

74.  Bortelson,  G.C.   and  G.F.  Lee.   Phosphorus, Iron, and Manganese
     Distribution  in   Sediment   Cores of Six Wisconsin  Lakes.  Limnol.
     Oceanog.   19:794-801, 1974.
                                  B-32

-------
75.  Williams,  J.D.H.,  J.K.  Syers,  R.F. Harris,  and D.E. Armstrong.
     Adsorption and Desorption of Inorganic Phosphorus by Lake Sediments
     in  a  0.1 M NaCl System.   Environmental  Science and  Technology.
     4:517-519, 1970.

76.  Shukla, S.S., J.K. Syers, J.D.H. Williams, D.E.  Armstrong, and R.F.
     Harris.   Sorption  of Inorganic Phosphate by Lake Sediments.  Soil
     Sci. Soc. Amer. Proc.  35:244-249, 1971.

77.  Norvell,  W.A.   Insolubil ization  of Inorganic  Phosphate by Anoxic
     Lake Sediments.  Soil Sci. Soc. Amer. Proc.  38:441-445, 1972.

7b.  Pomeroy,  L.R.,  E.E.  Smith,  and  G.M.  Grant.   The  Exchange of
     Phosphate Between Estuarine Waters and Sediments.  Limnol. Oceanog.
     10:167-172, 1965.

79.  Spangler,  F.C.,  W.E.  Sloey,  and  C.W.  Fetter,  Jr.  Wastewater
     Treatment  by  Natural  and  Artificial  Marshes.  EPA-600/2-76-207.
     September 1976.

80.  Jury,  W.A.   Solute Travel-Time Estimates for Tile-Drained Fields.
     I.  Theory.  Soil Sci. Soc. Amer. Proc.   39:1020-1024, 1975.

81.  Jury,  W.A. .   Solute Travel-Time Estimates for Tile-Drained Fields.
     II.   Application  to  Experimental   Fields.   Soil  Sci. Soc. Amer.
     Proc.  39:1024-1028, 1975.

82.  Novak, L.T.,  D.C. Adriano, G.A. Coulman, and D.B. Shah.  Phosphorus
     Movement  in Soils:  Theoretical Aspects.  Journal of Environmental
     Quality.  4:93-99, 1975.

83.  Harter,  R.D.  and  B.B. Foster.  Computer Simulation of Phosphorus
     Movement Through Soils.  Soil Sci. Soc.  Amer. J.  40:239-242, 1976.

84.  Shah,   D.B.,  G.A.  Coulman,  L.T.   Novak,  and  B.G.   Ellis.   A
     Mathematical   Model  for  Phosphorus Movement in Soils.  Journal  of
     Environmental Quality.  4:87-92, 1975.

85.  Nielsen,  D.R.,  J.W. Biggar, and K.T. Erh.  Spatial  Variability of
     Field-Measured  Soil  Water  Properties.   Hilgardia.   42:215-259,
     1973.

86.  Jury,  W.A.,   W.R.  Gardner, P.G. Saffigna, and  C.B.  Tanner.  Model
     for Predicting Simultaneous Movement of  Nitrate  and Water Through a
     Loarny Sand.  Soil Science.  122:36-43, 1976.

87.  Pratt, P.F.,  J.E. Warneke, and P.A.  Nash.  Sampling the Unsaturated
     Zone  in  Irrigated  Field Plots.  Soil  Sci. Soc. Amer. J.  40:277-
     279, 1976.

88.  Rible,  J.M.,  P.A.  Nash, P.F. Pratt, and L.J.  Lund.  Sampling the
     Unsaturated  Zone  of  Irrigated  Lands   for  Reliable Estimates of
     Nitrate.  Soil Sci. Soc. Amer. J.  40:566-570, 1976.
                                  B-33

-------
89.  Pratt,   P.F.,  F.F.  Peterson,   and  C.S.    Holzhey.    Qualitative
     Mineralogy  and  Chemical  Properties of a Few Soils from Sao Paulo,
     Brazil.  Turrialba.  19:491-496,  1969.

90.  Kuo,  S.  and  E.G.  Lotse.    Kinetics   of   Phosphate  Adsorption by
     Calcium  Carbonate  and  Ca-Kaolinite.    Soil  Sci.  Soc.  Amer.  Proc.
     36:725-729, 1972.

91.  Griffin,  R.A.  and  J.J.    Jurinak.   Kinetics  of  the  Phosphate
     Interaction  With  Calcite.    Soil  Sci. Soc. Amer.  Proc.  38:75-79,
     1974.

92.  Adriano,  D.C.,  L.T.  Novak,  A.E.  Erickson, A.R.  Wolcott, and B.G.
     Ellis.   Effect  of  Long  Term Land Disposal by Spray  Irrigation of
     Food  Processing Wastes on Some  Chemical  Properties of the Soil  and
     Subsurface  Waters.   Journal  of Environmental  Quality.   4:244-248,
     1975.,

93.  Taylor,  A.W. and H.M. Kunishi.   Soil  Adsorption of Phosphates From
     Waste  Water.    In:   Factors  Involved  in  Land   Application  of
     Agricultural   and  Municipal   Wastes.    ARS-USDA  National  Program
     Staff,  Soil,  Water, and  Air  Sciences, Beltsville, Md.   1974.  pp.
     66-96.

94.  Schneider,  I.F.  and A.E. Erickson.  Soil  Limitations for Disposal
     of   Municipal   Wastewaters.     Michigan  Agricultural   Experiment
     Station.  Research Report  No.  195.   1972.

95.  Enfield,  C.G.  Phosphate  Transport Through Soil.   In:  Proceedings
     of  the  National  Conference   on Disposal  of Residues on Land, St.
     Louis, Mo.  1976.
                                  B-34

-------
                               APPENDIX C

                           HYDRAULIC CAPACITY
C.I  Introduction
The  hydraulic  capacity  of  the  soil   to accept and transmit water is
crucial to the design of rapid infiltration systems and important in the
design  of  most  slow rate systems.  The important hydraulic parameters
are  infiltration,  vertical  permeability (percolation), and horizontal
permeability.   In  this  appendix,  the  basic hydraulic properties are
defined  and  techniques  for  measurement  and  estimation  of the more
important  parameters  are presented.  Both vertical  and horizontal  flow
of groundwater are discussed, and an analysis of groundwater mounding is
presented.   The  relationship  between predicted hydraulic capacity and
actual operating rates is also discussed.
C.2  Hydraulic Properties
For purposes of this manual, hydraulic properties of soil  are considered
to  be those properties whose measurement involves the flow or retention
of  water  within the soil profile.  These properties include soil-water
characteristic  curve,  percent  moisture  at  saturation, permeability,
infiltration   rate,  specific  yield,  specific  retention,  and trans-
mi ssivity.  In  addition, the terms of field capacity, permanent wilting
point,  and drainability are commonly used in irrigation practice.   How-
ever, these  terms describe qualitative relationships—not unique,  meas-
urable properties.   The  concepts of field capacity and permanent wilt-
ing point  are  discussed  in conjunction with soil-water characteristic
curves.
Soil  permeability  and  infiltration  rate  are especially important to
system  design.   They  should  be determined by field testing;  however,
they  may  be  estimated  from  other  physical  properties (mentioned in
Section  F.3.3.1).  An in-depth discussion of the more common methods of
estimating or measuring both soil and aquifer properties is presented in
this   appendix.    Field   testing   procedures  for  determining  soil
infiltration  rates  and permeability are outlined in Section C.3, along
with  methods  of  analyzing  and interpreting test results.  Methods of
measuring  or estimating properties of groundwater aquifers are  outlined
in Section C.4.
     C.2.1  Soil-Water Characteristic Curve
Water in the soil below the saturation level  is held in the soil  against
the  force  of  gravity primarily by forces that result from the surface
                                   C-l

-------
tension of water, the cohesion of water molecules,  the adhesion of water
molecules  to  soil   surfaces, and other electrical  attractive forces  at
the  molecular   level.   The  energy  required   to  remove  water  from
unsaturated  soil  when  expressed  on a per unit mass of water basis  is
termed  the  soil-water  pressure  potential  or  matric potential.   Soil-
water pressure  potential   is expressed as  J/kg  or  erg/g.  The energy  is
sometimes  expressed  on  a unit volume basis in  which case it is  termed
soil-water  pressure. 2 The resulting units  (erg/cm?)  convert,, to those
of  pressure,  dyne/cm ,  or more commonly, bar   (10    dyne/cm ).  The
most common method of expressing the energy is on a unit weight basis  in
which  case  it  is termed soil-water pressure head or simply head. The
resulting  units,  erg/dyne,  convert  to centimetres.  Soil  tension and
suction  are  terms  that  also have been used to describe the energy  of
soil-water  retention,  but these terms make no  distinction among  units.
They  are also considered positive quantities, while the above terms are
negative quantities.
The  force by which water is held in the  soil  is  approximately inversely
proportional  to  the pore diameter.  Thus,  the larger the pore the less
energy  is  required to remove water.   As soil dries or drains, water is
removed  from  the larger pores first. The  water remains in the smaller
pores  because  it  is  held  more tightly.   Thus,  as soil-water content
decreases,  soil matric potential  increases.  The graphical  relationship
between  soil-water  content  and  matric potential   is  the soil-water
characteristic  curve.   Examples  of  such  curves  for several  different
types  of  soil   are  shown  in Figure C-l.   It should be mentioned that
different  curves  will  be obtained depending on whether the soil-water
content  is changed by drying or by wetting.  This  hysteresis phenomenon
is  due  primarily  to  soil  pore configurations.   In most cases we are
interested  in the soil-water characteristic curve  resulting from drying
or drainage.


It  is  apparent  from Figure C-l  and  the  previous discussion that°the
shape  of  the  soil-water characteristic curve is  strongly dependent on
soil   texture  and soil structure.  For example,  sandy soils have mostly
large  pores  of  nearly  equal size.   Consequently, nearly all water is
removed from sands at a very small matric potential.  On the other hand,
medium-textured,  loamy  soils  have a greater porosity than sands and a
wide  pore size distribution.  Thus, more water is  held at saturation in
soils  than  in  sands  and  it is removed much more gradually as matric
potential becomes larger.
Some important aspects of soil-water plant relations may be explained by
the  shape  of  the  soil-water  characteristic   curve.    In  irrigation
practice,  it has been common to describe the maximum amount of water in
soil  that  is  available  for  plant  uptake as the difference in water
content  at  field  capacity  (the  upper  limit)   and that at permanent
wilting point (the lower limit).  A soil  is said to be at field capacity
when  the rate of water removal from the  soil, due to drainage following
an  irrigation  or  heavy  rain,  begins   to be  reduced.  As such, field
capacity is not a unique value, but represents a general region of water
                                   C-2

-------
percentages  as  illustrated  in  Figure  C-2.    Using  the  soil-water
characteristic curve, field capacity then may be expressed as a range of
soil-water  pressure  potentials.  The range of potentials in the region
of  field  capacity  varies  with soil texture.  For sands, the range of
field  capacity  is about 10 to 15 J/kg or 0.1 to 0.15 bar.  For medium-
to fine-textured  soils,  the range is about 0.3 to 0.5 bar.  A value of
0.3 bar is commonly used as a rough approximation in these soils.
                               FIGURE C-l

                        SOIL-WATER CHARACTERISTIC
                      CURVES FOR SEVERAL SOILS [1]
                        SOIL WATER CONTENT, Qm

                    (MASS OF WATER/MASS OF DRY SOIL)
                 0          0.1         0.2
0. 3
                                                     FIELD C» PACI TY

                                                        (0.3  ba r )
             -200  -
             -400  -
             -600  -
             -BOO  -
            - I 000  -
            -1200  -

            -1600 I—I' ' —
The  time  required  for  a thoroughly wetted soil to drain to the field
capacity  region  is  also  dependent  on texture and structure.  In the
absence  of  significant evaporation or transpiration, field capacity in
pure  sands may be reached in a few hours; for coarse soils about 2 to 3
days; for medium- to fine-textured soils, a week or more; and for poorly
structured clays, much longer.
There  are  a  few  misconceptions  associated with the concept of field
capacity  that  should be pointed out.  The first is that field capacity
is  a  unique  property  of  a  soil.   It is apparent from the previous
discussion  that  field  capacity  expresses  only  a  crude qualitative
relation.   The second misconception is that no drainage occurs in soils
at  or  below field capacity.  In fact, drainage does not cease at field
capacity but continues at a reduced rate for a long time, as illustrated
                                   C-3

-------
in  Figure  C-2.    The  third  misconception  is  that  field  capacity
represents  the upper limit of water that is available to plants and any
*.i•* ^ AM«  •* n n 1 ^ yvst  ^m  s\\t f~* s\ e* r*  f\f f ^ £\l rl *^ar\a/*i^\* i.n 1 1 r\A I /%«* 4* <£w« ssm + L*SN *• s\ ^ 1
water  applied  in  excess  of field capacity will be lost from the soil
profile as deep percolation.  However, water in excess of field capacity
is available to plants while it remains in contact with plant roots.
                               FIGURE C-2

                       FIELD CAPACITY RELATIONSHIP
                           0.4
                           0. 3
                          0. 2
                                        REGION OF
                                      'FIELD CAPACITY
                                 2    4    6   8   1012

                                DAYS AFTER IRRIGATION
The lower limit of water availability, the permanent wilting point, like
field  capacity,  is not a unique value but a range of water percentages
over  which the rate of water taken up by the plant is not sufficient to
prevent  wilting.  The ability of the plant to take up water is directly
related to the matric potential of the soil-water rather than the actual
water  content.   It  has  been found that most plants exhibit permanent
wilting  when  the  soil-water matric potential is in the range of 1 500
J/kg (15 bars).
If  it is assumed that the so called available reservoir of water is the
water  content  between field capacity and permanent wilting point, some
general  observations  can  be  made  regarding the effect of texture on
irrigation  scheduling.  From  the  shapes  of  the  various  soil-water
characteristic  curves  shown  in Figure C-l,  it is apparent that sandy
soils  have  a  relatively small difference in water content between the
regions  of  field  capacity  and  permanent  wilting.  Medium- to fine-
textured soils,  on the other hand, exhibit a rather large difference in
water content between field capacity and permanent wilting point.
Another generalization  that  can  be made is that coarse soils approach
the  permanent  wilting  point  very rapidly with small changes in water
content.  Thus,  plants grown in such soils would be expected to exhibit
                                   C-4

-------
wilting  symptoms  quite   suddenly.   Medium-  to  fine-textured  soils
approach  permanently  wilting  point more gradually and plants grown on
these soils will likely show very gradual signs of wilting.


Soil-water  characteristic  curves  generally  must be determined in the
laboratory  using  techniques  described  in  Taylor  and  Ashcroft [1].
Published  soil  moisture versus matric potential data are available for
selected   typical   soils.   The  USDA  Agricultural  Research  Service
Publication  41-144  [2]  provides such data for 200 typical  soils in 23
states.   In  addition,  bulk  density,  total  porosity,  and saturated
vertical permeability data are presented in this compendium.
     C.2.2  Percent Moisture at Saturation
The  percent  moisture at saturation or saturation percentage is defined
as  the number of grams of water required to saturate  100 grams of air-
dry soil.   It  is  a  convenient parameter to measure since a saturated
paste  is  normally  prepared for other analyses.  Saturation is reached
when  the  soil  surface  glistens  but  no free moisture is present.  A
saturated  paste  will  not flow from a container unless shaken.  Due to
the subjective nature of the test, large variations in test results from
different  sources  are common.  Thus, saturation percentage data should
be used with caution.
Saturation percentage is a useful parameter because it provides a quick,
rough estimate of the available water-holding capacity of the soil.  The
field  capacity is approximately one-half the saturation percentage, and
about  one-half  the  field  capacity  of  the  soil  can  be considered
available  to  plants.  Of course, a better estimate of available water-
holding capacity  can  be obtained from soil-water characteristic curves
as previously 'described.


The  value of saturation percentage is related to soil texture.  Typical
ranges for various soil textures are presented in Table C-l.
     C.2.3  Permeability
Soil  permeability  is  a  term  that  has  been  used rather loosely to
describe  the  ease  with which liquids and gases pass through soil.  In
this  manual,  the  term  permeability will be synonymous with hydraulic
conductivity.   Hydraulic  conductivity  is the more descriptive and the
preferred  term,  but,  for  the  sake  of  consistency with much of the
literature,  permeability  will be used in this manual.  These terms are
most  easily defined if a few basic concepts of  water flow in soils are
introduced first.
                                   C-5

-------
                                TABLE C-l


                    RELATION OF SATURATION .PERCENTAGE
                             TO SOIL TEXTURE
                         Soil texture    Saturation % range


                       Sand or loamy sand      Below 20

                       Sandy loam             20-35

                       Loam or silt loam        35-50

                       Clay loam              50-65

                       Clay                  65-135

                       Peat or muck           Above 135
In general, water moves through  soils  or  porous  media in accordance with
Darcy's law:


                               q =  K dH/dl                       (C-l)


where  q  =  flux (flow)  of  water per  unit  cross sectional areas,  in/h
             (cm/h)
       K  =  permeability (or  hydraulic conductivity), in./h (cm/h)
   dH/dl  =  total head (hydraulic)  gradient,  ft/ft (m/m)


                                                         Q
The  total  head (H)  is the  sum  of  the soil-water pressure head (h), and
the  head  due  to gravity (Z),  or  H = h  +  Z.  The hydraulic gradient is
the  change  in  total  head  (dH)   over  the  path  length (dl).  These
relationships   are    illustrated   schematically   for   saturated  and
unsaturated conditions in Figure C-3.
The  permeability  is  defined  as   the   proportionality  constant,  K .
Permeability  (K) is not a  true constant  but  a rapidly changing function
of water content.  Even under conditions  of constant water content, such
as  saturation,  K  may vary over time due to increased swelling of clay
particles,  change  in  pore  size  distribution due to classification of
particles,  and  change  in the  chemical  nature  of  the  soil-water.
However,  for  most purposes saturated permeability  (K )  values can be
                                    C-6

-------
considered  constant  for  a  given soil.  In general, the  K  value for
flow  in  the  vertical   direction  will  not  be  equal   to   Kin the
horizontal direction.  This condition is known as anisotropic.
                               FIGURE C-3

            SCHEMATIC SHOWING RELATIONSHIP OF TOTAL HEAD (H),
               PRESSURE HEAD (h), AND GRAVITATION HEAD (Z)
                           FOR SATURATION FLOW
                                                         V V,
                                                         AH =
                       SATURATED FLOW
The  permeability  of  soils  at  saturation  is  an important parameter
because  it  is  used  in  Darcy's equation to estimate groundwater flow
patterns (see Section C.4) and is useful  in estimating soil  infiltration
rates.  Permeability can be estimated from other physical properties but
much  experience  is  required and results are not sufficiently accurate
for design purposes.
As  suggested  by the inclusion of textural  classification in Tables 3-7
and  3-9,  soil  permeability  is  determined  to a large extent by soil
texture  with  coarse  materials generally having higher conductivities.
However,  in  some cases the soil structure may be equally as important.
A   well  structured  clay  with  good  stability  can  have  a  greater
permeability than a much coarser soil.
Permeability  of  soils is also affected by the ionic nature of the soil
water.   A  simplified  explanation  of  this  effect  is  given.   Clay
particles  in  the  soil  are  negatively charged due to substitution of
lower  valence  atoms for higher valence atoms (e.g., Al3+  for Si 4+) in
                                   C-7

-------
the  crystal structure.  Because of the  charge,  the  clay  particles  repel
each  other  and  remain  dispersed  in   the   soil   unless  the  charge  is
neutralized  by  positively  charged  cations   in the  soil-water.   Thus,
waters  high  in salts will contain sufficient cations to neutralize the
clay  particles  and  allow  them  to come  close enough together so that
short-range  molecular  attractive  forces  will  unite, or flocculate the
particles.   Flocculation  of particles  will result  in larger soil  pores
and increased permeability.  Thus, waters low  in salts may  result in low
permeability problems.


The type of ion in the soil-water also affects permeability.  Water with
larger  sodium  percentages can cause reduced  permeability.   This occurs
because  the  sodium ion in its hydrated state is much larger than  other
ions,  calcium  and  magnesium in particular.   Thus, the  layer  of sodium
ions  necessary  to  neutralize  clay particles is  thicker and the clay
particles  are restricted from coming together and remain dispersed.   As
a  result,  the  permeability of the soil is low. If  sufficient salt  is
present  in  the soil-water, the layer of sodium ions  will  be suppressed
to  the  point that clay particles will  flocculate and permeability will
be  adequate.   However,  the salt concentration may be so  high that the
growth of plants may be restricted (see  Section  5.6.2.3).


The  type of vegetation will also affect the permeability of soil within
the  root  zone.  The effects of ions and vegetation on permeability are
not  of concern for groundwater aquifers because they  are below the root
zones and contain little, if any, clay.
As previously discussed, the permeability  of  soil  varies  dramatically  as
water  content is reduced below saturation.   Since matric potential  also
varies  as a function of water content in  accordance  with the  soil-water
characteristic  curve,  permeability   may  be described as a function  of
matric  potential.   The  inverse  relationship  between permeability and
matric  potential is illustrated for  soils of several  different textures
in  Figure  C-4.   The  significant  relationship   to note is that the
permeability  of sandy soils, although much higher at saturation (matric
potential  =  0)  than loamy soils, decreases more rapidly as  the matric
potential  becomes  more negative.   In most cases, the permeabilities  of
sandy  soils  eventually  become  lower than the medium  soils.   This
relationship  explains  why  a  wetting front moves more  slowly in sandy
soils  than  medium  or  fine soils after  irrigation  has  stopped and why
there  is  little  horizontal spreading of moisture in sandy soils after
irrigation.
Estimating  water  movement  under  unsaturated  conditions  using  Darcy's
equation  and   unsaturated    K   values   involves   relatively   complex
mathematical  techniques.  A discussion of such  techniques  is  not within
the  scope  of  this manual.  The user is  referred to Kirkham  and Powers
[3] or Klute [4] for further details on the subject  of unsaturated flow.
                                    C-8

-------
                               FIGURE C-4

                    PERMEABILITY AS A FUNCTION OF THE
                 MATRIC POTENTIAL FOR SEVERAL SOILS [1]
                         COACHELL*  LOAMY
                            FINE SAND
                                               _ 0 . 01
                                                 o. ooi  2

                                   /~*~~^- CH I NO          uj
                        ,.-(lOH SAND•  *'   SILTY  _0.0001  °-
                    U?tR*ll-.«i	~^^*       CL*Y
                    0	    —«^         LOAM

                                                 0.00001
                     -50   -40   -30   -20   -10

                       MATRIC POTENTIAL, I/kg
     C.2.4  Infiltration Rate
The  infiltration  rate  of a soil is defined as the  rate  at which water
enters  the  soil from the surface.  When the soil profile is  saturated,
the  infiltration  rate is equal to the effective saturated permeability
of  the  soil  profile.   This  occurs  because at saturation  the matric
potential    (h)   is  zero  at  all  depths  and the  total head  gradient
(d[h + z]/dz) is equal to unity.  Thus, the  flux  q   is  equal  to k   ac-
cording to Darcy's law (Equation C-l).


When the soil profile is relatively dry, the infiltration  rate is higher
because  water  is  entering  large  pores and cracks.   With time, these
large pores  fill and clay particles swell reducing the infiltration  rate
rather  rapidly  until  a  near  steady-state value is approached.   This
change  in   infiltration  rate  with  time   is shown  in  Figure C-5   for
several  different  soils.   The effect of both texture  and structure on
infiltration  rate  is  illustrated  by the  curves in Figure   C-5.    The
Aiken  clay  loam has good structural stability and actually has  a higher
final  infiltration  rate  than the sandy soil.  The  Houston black clay,
however, has very poor structure and infiltration drops  to near  zero.
As  with  permeability,  infiltration  rates  are  affected  by  the  ionic
composition  of  the  soil-water and the type of vegetation.  Of  course,
any tillage of the soil surface will affect infiltration  rates.   Factors
which  have  a tendency to reduce infiltration  rates  include clogging  by
organic  solids  in  wastewater,  classification of fine  soil particles,
clogging due to biological growths, and gases produced  by soil  microbes.
                                    C-9

-------
                               FIGURE C-5

                     INFILTRATION RATE AS A FUNCTION
                      OF TIME FOR SEVERAL SOILS [1]
                        o.


                        0.
                     c

                     e  0-


                     .f  0.


                     -'  o.
                     <
                     tt
                        0.
                     z
                     o
                     ^  0.
                     •<
                     cr

                     ±  °-
                     u.
                     z  o.


                        0.
20


1 8


I 6


1 4


1 2


1 0


08


06


04


02


 0
            104*
            — -.

  CROWN SANDY LOAM
            SILT

HOUSTON  BLACK CLAY
                              20  40 60 80 100120 140

                                    TIME,  min
The  steady-state infiltration rate is extremely important and generally
serves  as  the basis for selection of the design hydraulic loading rate
for  slow  rate  and  rapid  infiltration   systems.   A  more  detailed
discussion of soil  infiltration, including field measurement techniques,
is presented in Section C.3.
     C.2.5  Drainability
Drainability is a qualitative term that is commonly used in soil surveys
and  elsewhere  to  describe  the  relative  rapidity  and extent of the
removal  of  water  from  the  root  zone by flowing through the soil to
subsoils  or  aquifers.   A  soil  is  considered  well-drained if, upon
saturation, water is removed readily, but not rapidly.  A poorly-drained
soil  is one in which the root zone remains waterlogged for long periods
of  time  following  saturation  and insufficient oxygen supply to roots
becomes  growth limiting to most .plants.  An excessively-drained soil is
one  from which the water is removed so completely that most crop plants
suffer from lack of water.
In  general,  loamy  soils are well-drained and provide the best balance
between drainage and water holding capacity for crop production.  Poorly
structured, fine, or moderately fine textured soils normally are poorly-
drained  and  are best suited to overland flow systems.  Sandy soils are
often excessively-drained and best suited to rapid infiltration systems.
                                  C-10

-------
It  should be recognized that the drainability of a  soil  profile.will  be
determined  by  the  most  restrictive  layer  in  the  profile.  Thus, a
shallow  sandy  surface  layer  underlain by a poorly-drained clay layer
will be poorly-drained.
     C.2.6  Specific Yield and Specific Retention
Specific  yield and specific retention are related properties  that are a
measure of the amount o.f groundwater an aquifer will yield upon pumping.
Specific  yield is the amount of water that will drain by gravity from a
saturated aquifer divided by the bulk volume of the aquifer.   This value
is  typically 10 to 20% for unconfined aquifers [5].  Specific retention
is  equal  to  the  porosity  (subsurface void space) minus the specific
yield, under  saturated  conditions.   The  relationship  among specific
yield, specific retention, and porosity is shown in Figure C-6.
                               FIGURE C-6

                    POROSITY, SPECIFIC RETENTION, AND
               SPECIFIC YIELD VARIATIONS WITH GRAINS SIZE,
                   SOUTH COASTAL BASIN, CALIFORNIA [5]
             50

             45


             40

             35

             30


             25

             20

             1 5

             1 0


              5

              0
I   I    I
                  1/16 1/8 1/4  1/2  1   2   4   8   16  32   64  128 256


                              MAXIMUM 10% GRAIN  SIZE,  mm
                                   C-ll

-------
     C.2.7  Transmissivity
Transmissivity is a parameter that is sometimes measured in the field as
part  of  a method to determine horizontal  permeability of aquifers [6].
Transmissivity   T   is the rate at which water is transmitted through a
unit  width of the aquifer under a unit hydraulic gradient.  It is equal
to the permeability  K  multiplied by the aquifer thickness.


C.3  Soil Infiltration Rate and Permeability Measurements


Field  measurements  of  soil  infiltration rates and permeability are an
essential part of the design of rapid infiltration systems and most slow
rate  systems.   These  hydraulic  parameters serve as the basis for the
designer's  selection  of  an  application  rate that will be within the
hydraulic  capacity  of the soil at the proposed site.  In this section,
the  principal  methods  for  measuring  infiltration rates and vertical
permeability are reviewed along with procedures for using the field test
results  to  obtain infiltration equations that are useful in the design
of  irrigation  systems.  The relation between infiltration and vertical
permeability  is  discussed.   Measurement  of soil moisture profiles is
also addressed.
     C.3.1  Infiltration
Infiltration  refers to the entry of the water into the soil.   Hydraulic
or liquid loading is infiltration over a long term (a year,  for example)
and  includes  resting  or  drying  periods.    The  factors   that affect
infiltration  have  been  thoroughly discussed in the literature [7]  and
must be firmly kept in mind when planning and making field measurements.
Otherwise,  the  measurements, which are relatively easy to  make, may be
meaningless for the intended purposes.
          C.3.1.1  Interpretation and Use of Infiltration Data
As  previously  mentioned,  (Section  C.2.4),  when water is applied to  a
soil  that  is  below field capacity,  the rate of infiltration generally
decreases with time, approaching a nearly constant or steady state value
after  several  minutes  or  hours  of  application.    However,  initial
infiltration  rates may vary considerably, depending  on the initial  soil
moisture  level.   Dry  soil  has  a  higher  initial  rate than wet soil
because  there  is more empty pore space for water to enter.  The effect
of  soil   moisture level  on initial  infiltration rates and the change in
infiltration  rate  as  a function of  time is  illustrated in Figure C-7.
The  short-term  decrease  in  infiltration rate is primarily due to the
change  in  soil  structure  and  the   filling  of  large  pores as clay
particles absorb water and swell.
                                  C-12

-------
                                FIGURE C-7

         INFILTRATION RATE CURVES SHOWING THE  INFLUENCE  OF  INITIAL
          WATER CONTENT,  Q (FRACTION BY VOLUME),  ON  INFILTRATION
                   RATE COMPUTED FOR YOLO LIGHT CLAY [1]
                         0.4 i—
                         0.3
                         0.2
                         0. 1
                                    5       10

                                    TIME,  h
Long-term  decreases
place  over  several
                      in  the  steady state infiltration rates that take
                      months  of  application  are also observed.  These
decreases are the result of several factors, including (1) the migration
and  concentration  of  fine soil particles in the soil profile, (2)  the
buildup  of organic and biological solids in the soil  pores, and (3)  the
blockage  of  soil pores by gases produced by soil  microbes.  The steady
state  infiltration  rate  may be improved or maintained by soil tilling
and other management practices.
The  short-term  change in infiltration rate as a function of time is of
interest in the design and operation of irrigation systems.  A knowledge
of  how  cumulative  water  intake  varies  with  time  is  necessary to
determine  the  time of application necessary to infiltrate the quantity
of  water  required  to irrigate a crop.  The design application rate of
sprinkler  systems  is  selected  on  the basis of the infiltration rate
                                   C-13

-------
expected  at  the end of the application period.   The  short-term change
in infiltration rate can be closely approximated  by the simple equation:
                                  I = Atn                    (C-2)
where  I  =  infiltration rate, in./min
       A  =  a constant, representing the instantaneous intake rate at
             time = 1 (usually minutes)
       n  =  an exponent which for most soils is negative with values
             between 0 and -1


Integration  of  the rate equation yields an equation for the cumulative
intake  Y  at any time  t .   The equation has the following form:


                             Y = __L_tn + 1                  (C-3)
Data  from  infiltrometer  studies  can  be  plotted to yield cumulative
intake  curves from which the coefficients for Equations C-2 and C-3  may
be  obtained.  Alternatively, the cumulative intake may be computed as a
function of time using the  Green-Ampt infiltration model.  Knowledge of
the  vertical permeability profile and the initial  soil  moisture profile
is needed to apply this technique.  The  K  profile may be determined by
the  methods  described  in  Section C.3.3.   The  soil   moisture may be
determined  by  using  a  neutron moisture probe or gravimetric sampling
[1].   The calculation procedures are described by Bouwer for various  K
and  moisture  profiles [8, 9],  The advantage of the calculation method
over  infiltrometer  measurements  in  generating  Y  versus  t  data is
that the  uncertainty  associated  with  lateral  seepage under infnitro-
meters  is  avoided, and the  Y  versus  t  relationship can be computed
easily ,for  any  soil moisture profile.   Data obtained from the  Green-
Ampt model  can  be  plotted in the same  manner as infiltrometer data to
yield infiltration rate versus time curves.
The  most direct method to determine coefficients for Equation C-3  is to
plot  the  data  points  on  log-log paper with time on the abscissa and
cumulative  intake  on  the  ordinate, and to fit the best straight line
through  the  points.   An  example of such a plot for several different
soils  is shown in Figure C-8 [1].  The intercept of the curve at  t = 1
is  equal  to  A/n + 1   (not shown in Figure C-8), and the slope of the
line is equal to n + 1.
The  most  important  application for the cumulative intake curves is in
the  design and evaluation of border irrigation systems.  The curves may
be  compared  with  a  set  of intake family curves developed by SCS for
border  irrigation design, and the appropriate intake family can then be
selected.   Cumulative  intake  curves  may also be developed for furrow
                                  C-14

-------
irrigation  system  design  and evaluation.  However, infil
are  not  directly  applicable to furrow irrigation because
the  land is in contact with the water, and lateral seepage
large part'of the total intake.  Consequently, actual field
furrows  are  required  to develop infiltration rate versus
Infiltration  rate  curves  may be obtained by applying the
and  n  to  Equation C-2.   Infiltration  rate  curves  may
selecting sprinkler application rates.
      trometer data
       only part of
       represents a
       trials using
       time curves.
       constants  A
       be useful in
                               FIGURE C-8

          CUMULATIVE INTAKE CURVES SHOWING THE INFILTRATION OF
           WATER INTO SOIL FROM SINGLE RING INFILTROMETERS [1]
                               («= n + 1)
                30 i-
                         20    30  40  5060  80 100      200   300
          C.3.1.2  Soil Profile Drainage Studies
For   slow   rate   systems  that  are  operated  at  application  rates
considerably  in  excess  of  crop  irrigation requirements, it is often
desirable  to  know  how  rapidly the soil profile will drain and/or dry
after  application has stopped.  This knowledge, together with knowledge
of  the  limiting  infiltration  rate  of  the  soil and the groundwater
movement  and buildup, allows the designer to make a
of  the  maximum volume of water that can be applied
produce  adequate crops.  A typical moisture profile
time  following  an  irrigation  is  illustrated  in
initially saturated profile.
reasonable estimate
to a site and still
and its change with
 Figure C-9  for an
                                  C-15

-------
                               FIGURE C-9

                TYPICAL PATTERN OF THE CHANGING MOISTURE
                   PROFILE DURING DRYING AND DRAINAGE
                       0 —^WATER CONTENT    SATURATION
Moisture profile changes may be determined in the field by measuring the
soil-water tension at various times and at various depths in the profile
with  tensiometers.  Soil tension data can then be converted to moisture
content values by use of the soil-water characteristic curve of the soil
at each measured depth.  Soil-water characteristic curves are determined
by  laboratory  methods.   A  discussion of these methods and the use of
tensiometers is presented in Taylor and Ashcroft [1].
          C.3.1.3  Estimates of Infiltration From Soil Properties
Estimation  of  infiltration  and  percolation  rates without benefit of
actual  onsite  testing  is  an  undesirable  practice,  but the general
relationships  that have been established between hydraulic capacity and
soil  properties  through  experience  are  certainly reliable enough to
permit   preliminary   screening  of  several   available   sites.   Soil
scientists  generally agree that when a large  number of widely different
soils  are  considered,  no  single  factor  can  serve  as an index for
determining  the infiltration rate or permeability of an individual  soil
profile.


In  a  comprehensive study by O'Neal, it was concluded that structure is
probably  the  most  important  single soil  characteristic in evaluating
hydraulic  characteristics,  but  it was impossible to estimate these on
the  basis  of structural factors alone [10].   The approach suggested in
                                 C-16

-------
the  basis  of  structural  factors  alone [10].   The approach suggested in
the  study  resulted  in  only fair precision using four principal factors:
(1)  relative   dimension   (both horizontal  and  vertical) of structural
aggregates, (2)  amount  and direction  of overlap of aggregates (3)  num-
ber  of   visible  pores,   and  (4) texture.   None of these factors, when
considered  singly,   was   a reliable indicator of permeability, and each
one  had  to  be considered with reference to all the others.  The seven
soil permeability classes  used by the SCS are as follows:


                    	Class	   Soil permeability, in./h

                    Very slow              <0.06
                    Slow                 0.06-0.2
                    Moderately slow         0.2-0.6
                    Moderate              0.6-2.0
                    Moderately rapid    -    2.0-6.0
                    Rapid                6.0-20.0
                    Very rapid            >20.0
                    1  in./h = 2.54 cm/h
Using these classes, the  soils  experts  who  participated in O'Neal's work
were  able to estimate  the  correct permeability class for 68% of the 271
horizons  examined,  and  they   were  within  one  class  ranking for an
additional  24%.   Note  particularly,   however, that these results were
achieved  by trained persons.   Moveover,  it must be remembered that even
within a particular class there is room for an error of up to 400%.


The  difficulty  is  that  even  if  permeability  could  be  accurately
determined   from   a   particular   property   (such  as  particle  size
distribution),  it  would  still   be  influenced  by  factors which that
particular measurement  could  not account for.   These might include grain
orientation,  colloid   migration  or  swelling,  bulk density changes by
compaction,  and  chemical  or   biological  effects.  Thus, it would seem
reasonable  for  reviewing  agencies  to  insist  on at least some field
measurements,  of  the  type  recommended  in   Chapter  4,  for all land
treatment  systems  where  the   intended  application  rates are well in
excess of the known evapotranspiration  rates.


          C.3.1.4  Infiltration Measurement Techniques
The value that is required  in  land  treatment is the long-term acceptance
rate  of  the  entire   soil  surface  on  the  proposed site for the actual
wastewater  effluent  to  be applied.  The value that can be measured is
only a short-term equilibrium  acceptance rate for a number of particular
areas  within  the  overall  site.    It   is   strongly  recommended  that
hydraulic  tests  of  any   type   be conducted with the actual wastewater
whenever  possible.   Such  practice   will   provide valuable information
                                  C-17

-------
relative  to  possible   soil-wastewater   interactions which might create
future  operating  problems.   If  suitable wastewater is not available at
the  site, the ionic composition  of  the water  used should be adjusted to
correspond to that of the wastewater.  Even  this  simple step may provide
useful  data  on  the   swelling of expansive clay minerals due to sodium
exchange.


The theory of infiltration,  in which great strides have been made in the
past  decade, has simply not yet  found practical  application in the land
treatment  of  wastewater.   Modeling  the   physics of unsaturated flow,
while  important,  has   not  answered  the   present  need for simple and
economical  assessment   of   soil  hydraulic  capacity.  Measurements have
been  made by numerous  different  techniques  without follow-up studies to
relate  operating  results   to the  original  measurements.  Research is
needed in this area to  improve existing design techniques.
There are many potential  techniques  for  measuring infiltration including
basin  flooding,  sprinkler  infiltrometers,  cylinder infiltrometers, and
lysimeters.   The technique  selected should  reflect the actual method of
application  being  considered.   The area   of   land  and the volume of
wastewater  used  should   be  as  large   as   practical.   The  two  main
categories  of  measurement   techniques   are  those  involving  flooding
(ponding  over  the  soil  surface)   and rainfall  simulators (sprinkling
infiltrometer).   The   flooding   type of infiltrometer supplies water to
the  soil  without  impact,  whereas  the  sprinkler infiltrometer provides
impact  similar  to  that of natural  rain.   Flooding infiltrometers are
easier  to operate than spinkling infiltrometers, but they almost always
give  higher  equilibrium infiltration    rates.    In  some  cases,  the
difference  is  very   significant, as shown  in Table C-2.  Nevertheless,
the  flooding  measurement techniques are generally preferred because of
their simplicity.
                                TABLE  C-2

          COMPARISON OF  INFILTRATION MEASUREMENT  USING FLOODING
                     AND SPRINKLING TECHNIQUES [11]
                                     Equilibria infiltration
                                          rate, in./h

                    Measurement       Overgrazed  Pasture, grazed but
                     technique        pasture   having good cover


              Double-cylinder
              infiltrometer (flooding)      1.11         2.35

              Type F rainfall
              simulator (sprinkling)       O.K         1.13


              in./h =2.54 cm/h
                                  C-18

-------
Before   discussing   these four techniques, it should be pointed out that
the  standard   U.S.   Public Health Service (USPHS) percolation test used
for  establishing   the  size  of  septic  tank  drain fields [12] is not
recommended  .except  for  very small  subsurface disposal fields or beds.
Comparative  field  studies have shown that the percolation rate from the
test  hole   is  always significantly higher than the infiltration rate as
determined   from    the   double-cylinder   (also  called  double  ring)
infiltrometer   test.    The  difference  between the two techniques is of
course  related* to the much higher percentage of lateral flow experienced
with  the  standard  percolation test.  The final rates measured at four
locations  on   a  30   acre  (12  ha)   site  using the two techniques are
compared in  Table C-3.   The lower coefficient of variation (defined as
the  standard   deviation  divided by  the mean value,  Cv  = O/M) for the
double-cylinder technique  is  especially   significant.   A  plausible
interpretation  is  that the measurement technique involved is inherently
more precise than the standard percolation test.

                                 TABLE C-3

          COMPARISON  OF INFILTRATION  MEASUREMENT USING STANDARD
         USPHS PERCOLATION TEST AND DOUBLE-CYLINDER INFILTROMETER3
                                   Equilibrium infiltration
                                        rate, in./h

                                 Standard USPHS  Double-cylinder
                      Location     percolation test  infiltrometer
1
2
3
4
Mean
Standard
deviation
Coefficient
of variation
48.0
84.0
60.0
138.0
82.5
40.0
0.48
9.0
10.3
14.4
12.0
11.6
2.3
0.20
                     a.  Using sandy soil free of clay.

                     1 in/h = 2.54 cm/h
               C.3.1.4.1   Flooding Basin Techniques


Where pilot basins have  been  used for determination of infiltration, the
plots  have  generally ranged from  10 ft2  (0.9 m2)  to  0.25 acre (0.1
ha).    Larger   plots   are  provided  with  a  border  arrangement  for
application  of the water.   If the plots are filled by hose, a canvas or
burlap  sack  over  the  end of the hose will minimize disturbance of the
soil  [7].   Although  basin   tests  are  desirable,  and should be used
whenever  possible, there  probably will not arise many opportunities to
                                   C-19

-------
do  so because of the large volumes of water needed for measurements.  A
sample  basin  is shown in Figure C-10.   In  at least one known  instance,
pilot  basins  of large scale (5 to 8 acres  or 2  to 3.2 ha)  were  used to
demonstrate feasibility and then were incorporated into the  larger  full-
scale system [13].
                               FIGURE C-10

             FLOODING BASIN USED FOR MEASURING  INFILTRATION
               C.3.1.4.2  Sprinkler Infiltrometers
Sprinkler  infiltrometers  are  used primarily to determine the limiting
application  rate  for  systems  using  sprinklers.   To measure the  soil
intake rate for sprinkler application, the method presented by  Tovey and
Pair  can be used [14].  The equipment needed includes a trailer-mounted
water  recirculating  unit, a sprinkler head operating inside a circular
shield  with  a  small side opening, and approximately 50 rain  gages.   A
schematic  diagram  of a typical sprinkler infnitrometer is presented in
Figure C-ll.  A 2  ton   (1 814 kg) capacity trailer houses a 300  gallon
                         tank  and 2 self-priming centrifugal pumps.   The
                        have sufficient capacity to  deliver at least 100
                         50  lb/in.2  (34.5   N/cm?)   to  the  sprinkler
nozzle,  and  the  return  flow  pump should be capable of recycling all
excess water from the shield to the supply tank.  The circular sprinkler
shield  is  designed  to  permit  a  revolving head  sprinkler to operate
normally  inside  the  shield.   The  opening  in the side of the shield
(1 135 L) water supply
sprinkler  pump  should
gal/min  (6.3  L/s)   at
                                  C-20

-------
                                                                FIGURE C-ll

                                                 LAYOUT OF  SPRINKLER INFILTROMETER  [14]
                  2 ton  TRAILER
o
ro
                          300. gal
                       WATER SUPPLY
                           TANK
                                                     AUXILIARY
                                                    WATER  SUPPLY
                                PRESSURE
                                  GAGE
                                                                                — SPRINKLER
                                                                                     HEAD
                                             ooooootfo
                                             o  o o  o  o o  o
                                             o  o o  o  o o  o
                                                                                                                    RAIN GAGES
                                                                                                                     5 ft
                                                                                     SPRINKLER
                                                                                      SHIELD
                                                                                                              • j
VALVES
                                   1 ton = 907.2  Kg
                                   1 ft =0.305  m
                                   1 gal =3.785  L

-------
restricts  the  wetted  area  to about one-eighth of a circle.  Prior to
testing,  the  soil  in the wetted area is brought up to field capacity.
Rain  gages  are  then  set  out in rows of three spaced at 5 ft (1.5 m)
intervals  outward  from  the  sprinkler in the center of the area to be
wetted.   The  sprinkler  is  operated  for about 1  hour.  The intake of
water  in  the  soil  at  various  places  between  gages is observed to
determine  whether  the  application rate is less than, greater than, or
equal  to  the  infiltration rate.  The area selected for measurement of
the  application  rate  is  that  where  the application is equal  to the
infiltration  rate,  i.e.,  where the applied water just disappears from
the  soil  surface as the sprinkler jet returns to the spot.  At the end
of  the  test (after 1 hour), the amount of water caught in the gages is
measured  and  the  intake  rate is calculated.  This calculated rate of
infiltration  is  equal  to  the limiting application rate that the soil
system can accept without runoff.


               C.3.1.4.3  Cylinder Infiltrometers


A useful reference on cylinder infiltrometers is Haise et al. [15].  The
basic  technique,  as  currently  practiced, is to drive or jack a metal
cylinder  into  the  soil   to  a depth of about 6 in. (15 cm) to prevent
lateral  or  divergent flow of water from the ring.   The cylinder should
be  6 to  14 in.  (15 to 35 cm)  in diameter and approximately 10 in. (25
cm)  in  length.   Divergent  flow  is  further  minimized by means of a
"buffer zone" surrounding the central  ring.  The buffer zone is commonly
provided  by  another  cylinder  16 to  30 in.  (40 to 75 cm) in diameter
driven  to a depth of 2 to 4 in. (5 to 10 cm) and kept partially full of
water  during the time of infiltration measurements from the inner ring.
Alternatively,  a  buffer zone may be provided by diking the area around
the intake cylinder with low (3 to 4 in. or 7.5 to 10 cm) earthen dikes.
The  quantity  of  water  that  might have to  be supplied to the double-
cylinder system during a test can be substantial  and might be considered
a  limitation  of the technique.  For highly permeable soil, a 1  500  gal
(5 680 L)  tank truck might be needed to hold  a  day's water supply for a
series of tests.  The basic configuration of the equipment during a test
is shown in Figure C-12.
This   technique   is   thought  to  produce  data  that  are  at  least
representative  of  the  vertical  component of flow.   In most soils,  the
infiltration  rate  will  decrease  throughout  the  test and approach  a
steady  state value asymptotically.  This may  require as little as 20 to
30  minutes  in some soils and several  hours in others.   The test cannot
be terminated until the steady state is attained or else the results  are
meaningless (see Figure C-7).
                                 C-22

-------
                               FIGURE C-12
                                      »

                     CYLINDER INFILTROMETER IN USE
 BUFFER POND

   LEVEL
        7
                           GAGE INDEX
                           ENGINEER'S  SCALE
                           WELDING ROD
                           HOOK
                                                   WATER SURFACE
                                     —  INTAKE CYLINDER  —
GROUND LEVEL —^
                                   C-23

-------
The following precautions concerning  the  cylinder  infiltrometer  test  are
noted.

     1.   If  a sprinkler or flood application  is  planned,  the cylinders
          should  obviously  be  placed  in surficial  materials.   If  rapid
          infiltration  is  planned,  pits must   be excavated to expose
          lower horizons that will  constitute the  bottoms of  the basins.

     2.   If  a  more  restrictive layer  is present below the  intended
          plane  of  infiltration  and  this layer  is close  enough to  the
          intended plane to interfere,  the infiltration  cylinders should
          be embedded into this  layer to  ensure a  conservative estimate.
          The  method  of  placement  into   the   soil   may   be  a  serious
          limitation.   Disturbance   of   natural   structural  conditions
          (shattering  or  compaction)   may   cause  a  large  variation  in
          infiltration   rates   between replicated   runs.    Also  the
          interface between the  soil  and the metal  cylinder  may become a
          seepage  plane,  resulting  in abnormally  high    rates.    In
          cohesionless  soils (sands and gravels),  the poor  bond  between
          the  soil  and  the cylinder   may  allow seepage around the
          cylinder  and cause "piping."   This can be observed easily and
          corrected,  usually by moving a  short distance  to a new
          location  and  trying   again.   Variability   of data  caused  by
          cylinder  placement can  largely   be   overcome by leaving the
          cylinders  in place over an extended period  during a  series  of
          measurements [7].
Knowledge of the ratio of the total  quantity  of  water  infiltrated  to  the
quantity  of  water remaining directly  beneath the  cylinder  is  essential
if one is interested only in vertical water movements.   If no correction
is  made  for  lateral  seepage,   the   measured  infiltration rate  in  the
cylinder  will  be  well   in  excess of  the "real"  rate [16].  Several
investigators  have  studied  this  problem   of  lateral  seepage  and have
offered suggestions for handling  it  [16, 17,  18].


As  pointed  out  by  Van  Schilfgaarde  [19], measurements  of  hydraulic
conductivity  on  soil  samples  often   show  wide   variations   within  a
relatively  small  area.    Hundred-fold  differences   are common on some
sites.   Assessing  hydraulic  capacity for a project  site is especially
difficult  because  test plots may have adequate capacity when  tested as
isolated portions, but may prove  to  have inadequate capacity after water
is  applied  to  the  total   area for   prolonged  periods.  Parizek  has
observed  that  problem  areas can  be  anticipated  more  readily  by field
study  following spring thaws or  prolonged periods  of  heavy  rainfall  and
recharge  [20].   Runoff, ponding, and  near saturation conditions  may be
observed  for  brief periods at sites where drainage  problems are  likely
to occur after extensive application begins.
                                   C-24

-------
Although far too few extensive tests have been made to gather meaningful
statistical  data  on  the  cylinder  infiltrometer  technique,  one very
comprehensive study is available from which tentative conclusions can be
drawn.   Burgy  and  Luthin  reported  on  studies  of three 40 by 90 ft
(12.2 x 27.4 m) plots of Yolo silt loam characterized by the  absence of
horizon  development  in  the  upper profile [11].  The plots were diked
with  levees 2 ft (0.6 m) high.  Each plot was flooded to a depth of 1.5
ft  (0.5 m),  and the time for the water to subside to a depth of 0.5 ft
(0.15 m)  was  noted.   The  plots  were  then  allowed  to drain to the
approximate field capacity and a series of cylinder infiltrometer tests--
357 total--were made.


Test results from the three basins located on the same homogeneous field
were   compared.    In   addition,  test  results  from  single-cylinder
infiltrometers with no buffer zone were compared with those from double-
cylinder infiltrometers.   The  inside  cylinders  had  a  6 in. (15 cm)
diameter;  the  outside  cylinders,  where  used,  had  a 12 in. (30 cm)
diameter.
For  this  particular soil, the presence of a buffer zone did not have a
significant effect on the measured rates.  Consequently, all  of the data
are  summarized on one histogram in Figure C-13.  The calculated mean of
the distribution shown is 6.2 in./h (15.7 cm/h).  The standard deviation
is 5.1 in./h (12.9 cm/h).
Burgy  and  Luthin  suggest  that  the  extreme  high  values,  while not
erroneous,  should  be rejected in calculating the hydraulic capacity of
the  site.  Physical inspection revealed that these values were obtained
when  the  cylinders intersected gopher burrows or root tubes.   Although
these  phenomena had an effect on the infiltration rate, they should not
be included in the averaging process as they carried too much weight.
As  a  criterion  for  rejection,  Burgy and Luthin suggest omitting  all
values greater than three standard deviations from the mean value.  They
further  suggest  an  arbitrary  selection  of  the  mean  and  standard
deviation  for  this  procedure  based  on  one's  best  estimate of  the
corrected values rather than the original  calculations.  From inspection
of  the histogram, these values might be selected as about 5 in./h  (12.7
cm/h)  and 3.5 in./h (8.9 cm/h), respectively.  Thus, all values greater
than  5.0  + 3(3.5), or 15.5 in./h (39.4 cm/h) are arbitrarily rejected:
a total of 12 of the 357 tests made (3.4%).
Because  it  is  important to provide conservative design parameters for
this  work,  however, it is recommended that all  values greater than two
standard  deviations  from  the mean be rejected.  For the example,  this
results  in the rejection of all values greater than 5.0 + 2(3.5),  or 12
in./h  (30.5 cm/h)  from  the   average.   A  recomputation  using   this
                                  C-25

-------
                                                           FIGURE C-13



                                    VARIABILITY  OF INFILTROMETER TEST  RESULTS ON RELATIVELY

                                                      HOMOGENEOUS SITE  [20]
o
I
ro
13




12



11




10



 9



 8




 7



 6




 5




 4



 3




 2




 1




 0
                                                                        _L
                                                                               J_
                                                                                       _L
                                                                                                  _L
                                                                                                     J_
                                       6   8   10   12  14  16   18  20  22  24  26  28  30  32  34  36   38  40  42  4445



                                                     AVERAGE  INFILTRATION RATE,  in./h
                            1  in./h - 2.54 cm/h

-------
criterion  provides  a  mean  of  5.1   in./h  (12.5 cm/h)  and a standard
deviation  of 2.8 in./h (7.1 cm/h).  This average value is within 16% of
the  "true"  mean  value  of  4.4 in./h  (11.2 cm/h)  .as measured during
flooding tests of the entire plot.
The  main question to be answered now is, how many individual  tests  must
be  made  to  obtain an average that is within some given percent of the
true  mean,  say  at  the  90% confidence interval?  The answer has  been
provided  by  statisticians using the Student "T"  distribution.  Details
of  the  derivation  are  omitted here but can be  found in most standard
texts on statistics.
The  results  of  two  typical   sets  of  computations are summarized  in
Figures  C-14  and  C-15.   The  two  sets of curves are for 90% and 95%
confidence intervals.  The confidence interval  and the desired precision
are,  of  course,  basic  choices  that  the  engineer must make.   A 90%
confidence  in  the measured mean, which is within 30% of the true  mean,
may  be  sufficient  for  small  sites  where  neighboring  property  is
available for expansion if necessary.  On the other hand, 95% confidence
that  the  measured  value  -is   within  10% of the true mean may be more
appropriate  for  larger  sites or for sites where expansion will  not  be
easily accomplished once the project is constructed.
The  coefficient  of  variation  will   have  to  be estimated from  a  few
preliminary  tests  because  it  is the main plotting parameter in  these
figures.   As  an  example,  for  the  adjusted distribution of Burgy  and
Luthin's  data  with  a  coefficient  of variation estimated at 0.55,  at
least  23  separate  tests would be required to have 90% confidence that
the  computed  mean  would  be  within  20%  of  the  true mean value  of
infiltration.  Obviously, time and budget constraints must be considered
in making the confidence and accuracy  determinations; 3 to 4 man-days  of
work might be required to make 23 cylinder infiltrometer tests.
               C.3.1.4.4  Lysimeters
Lysimeter  studies,  using  either undisturbed cores (cohesive soils)  or
disturbed  samples  compacted  carefully  to,  or  near,   the field bulk
density  of  the undisturbed sample, may have potential  for bridging the
very large gap between short-term field tests with clean  water and long-
term pilot  scale  field  studies  with  the  actual    wastewater.   The
configuration  of  a typical lysimeter is shown in Figure C-16.   Smaller
diameters,  down  to  3  or  4 in. (7.6 or 10.2 cm),  have been used with
success,  especially for relatively undisturbed cores.  The gravel  layer
shown  in  the  figure  is  artificial   and was provided  only to prevent
clogging  at  the  outlet.  Screens and perforated or porous plates have
been used for the same purpose in other lysimeter designs.
                                   C-27

-------
                     FIGURE C-14


    NUMBER OF TESTS  REQUIRED FOR 90%  CONFIDENCE

     THAT THE CALCULATED MEAN IS WITHIN  STATED

              PERCENT OF THE TRUE MEAN
   100
10$
     0.1     0.2     0.3     0.4     0.5     0.6


                     COEFFICIENT OF VARIATION
       0.7
0.8
                     FIGURE C-15


    NUMBER OF  TESTS REQUIRED FOR  95% CONFIDENCE

     THAT THE  CALCULATED MEAN  IS  WITHIN STATED

               PERCENT OF THE TRUE MEAN
   100

    80


o   60
Ul
oe

=   40
a
UJ
O£


2   20
CO
UJ
I—


Z   10


-------
                                FIGURE C-16

                          LYSIMETER CROSS-SECTION
           4 ft
         (APPROX)
           6  in.
                 •"*•••
                             SOIL
                     GRADED GRAVEL
                     UNDERDRAIN
                                                         VENT PIPE
ADJUSTABLE
OUTLET
                1  ft =0.305 m

                1  in.= 2. 54 cm
If  clean  water  is  used  in lysimeter tests, close  agreement with  the
results  of  cylinder infiltrometer results should be  obtained, provided
that  the  infiltrometer  tests  were made carefully and with  sufficient
replicates (usually 6 to 12) [21].  With actual wastewater,  however,  the
results  will  not match.   In a study by Ongerth and Bhagat, the  18-inch
(45.7 cm)  diameter  lysimeter,  loaded  at somewhat less  than 100 Ib of
BOD/acre-d   (112  kg/ha-d),  averaged about 5  to 10% of the  infiltration
rates  observed  on  the undisturbed soils using cylinder  infiltrometers
and   clean  water   [22].   Follow-up  studies  on  a pilot  basin  of
approximately 0.25 acre (0.10 ha) showed that  rates significantly higher
than  those  observed in the lysimeters could be sustained  [23].   After 1
year  of  operation  the  infiltration  rate   from  the  pilot basin  has
averaged   about   25%  of  those  measured  by  the   original  cylinder
infiltrometer testing on this site.  This is almost three  times the rate
predicted from the lysimeter tests.  Exact reasons for these differences
are not known, but the packing of the disturbed soil into  the  lysimeters
is probably  a major factor.  This problem will be more critical for fine
textured  soils.   Much  more  information  from studies like  the one by
Ongerth and  Bhagat is necessary before general conclusions can be drawn.
                                   C-29

-------
     C.3.2  Relation Between Infiltration and Vertical  Permeability


Percolation,  the  movement  of  water through the soil, is a distinctly
different  property from infiltration, the movement of water through the
soil  surface  into the soil.  The measurement of the vertical  component
of  percolation  is  called  the  vertical  permeability.  In a study by
Bouwer   [24]  it  has  been  shown  that  the  steady  state  value  of
infiltration  of secondary wastewater effluents containing approximately
2b  mg/L  suspended  solids is about one-half of the potential  saturated
vertical permeability.
Although  the  measured  infiltration  rate  on  the particular site may
decrease  in  time  due  to  surface  clogging phenomena, the subsurface
vertical  permeability  at  saturation  will   generally remain constant.
That  is,  clogging in depth does not generally occur.  Thus, the short-
term measurement  of  infiltration serves reasonably well as an estimate
of  the  long-term  saturated  vertical   permeability if infiltration is
measured  over  a  large  area.  Once the infiltration surface begins to
clog,   however,  the  flow  beneth  the  clogged  layers  tends  to  be
unsaturated and at unit hydraulic gradient.
     C.3.3  Measurement of Soil  Vertical  Permeability
The  rate  at  which  water  percolates  through the soil  profile during
application  depends on the average saturated permeability  (1C)  of the
profile.   If  the  soil is uniform,   K  is constant with depth, and any
differences  in  measured  values  of   K   are  due  to  errors  in the
measurement  technique.   Average   K   then  may  be  computed  as  the
arithmetic mean:

                               (XT '  «^O   1^ O • • • 1^ —
                         K   = J	2	3_	n         (c_4)
                          am          n                    v    '

where  K,_ = arithmetic mean permeability
        GUI


Many  soil  profiles  approximate a layered series of uniform soils with
distinctly  different   K  values, generally decreasing with depth.  For
such  cases,  it  can  be  shown  that average  K  is represented by the
harmonic mean of the  K  values from each layer [25]:



                         Khm = d7—dT	r           (C-5)
                                1 j.  2 ,   .    n
                                    K2   '"Kn
where D = soil profile depth
     d  = depth of nth layer
      n
    K.   = harmonic mean permeability
                                   C-30

-------
If  a  bias  or  preference  for a certain  K  value is not indicated by
statistical  analysis of field test results, a random distribution  of  K
for  a  certain layer or soil region must be assumed.  In such cases, it
has been shown that the geometric mean provides the best estimate of  the
true  K  [25]:
                     v   - iv  .  v  .  v  ...  v \           (C-6)
                     Kgm ' (K1    K2   K3     V

where K   = geometric mean permeability


Methods available to measure vertical  saturated permeability in  the  soil
region  above a water table, or in the absence of a water table,  include
the  double  tube  [26,  27],  the gradient intake [27,  28], and  the air
entry .permeameter [29].
Each  method  requires wetting of the soil  to obtain  K  values.   During
wetting,  air  is  often  trapped in the soil pores, and long periods  of
infiltration  are  necessary  to  achieve  true  saturation.    Thus, the
measured    K    value   (K )   is   usually  less  than  the  saturated
permeability (Ks).  The air entry permeameter measures  K  in the wetted
zone  during  wetting, and the measured  K  is about 0.5  Ks   [29].  The
double  tube  and  gradient  intake  methods  required longer periods  of
infiltration,  and the soil becomes more nearly saturated.  Thus, the   K
value  determined  with  these  two methods may be somewhere  between 0.5
K. and K..
In the gradient intake and double tube methods,  permeability is measured
at  the  bottom  of  an  auger  hole,  so  these methods can be used  for
measuring   K   at  different  depths  in  a  profile.    The  air  entry
permeameter  is a surface device, and pits or trenches  must be dug  if it
is to be used for measuring  K  at greater depths.
C.4  Groundwater Flow Investigations


Groundwater  movement  through  soil and rock is important to the design
and  operation  of land treatment systems, especially rapid infiltration
systems.   Quantities  and  qualities of subsurface water will  likely be
altered  by  rapid  infiltration.   Estimating  subsurface water flow by
indirect  surface  methods  and  by  more  direct  subsurface methods is
described  in  this  section.   The  use  of hydraulic models to predict
groundwater movement also is described briefly.
                                  C-31

-------
     C.4.1  Groundwater Elevation Maps
Groundwater  elevation  maps  are  constructed  by interpolating between
measured  elevations  in  wells  and  drawing  contour  lines  of  equal
elevation.    The   movement  of  the  groundwater  is  in  a  direction
perpendicular  to  the contours from the higher to the lower elevations.
The flowrate can be estimated using Darcy's law, by measuring the length
dl  between groundwater elevation contours  dH .
Groundwater  maps  are used to identify zones of discharge and recharge.
Since groundwater flows downgradient, domes,  hills, and ridges represent
recharge  zones;  and  basins,  troughs, and  valleys represent discharge
zones.   Recharge and discharge zones are likely to occur where aquifers
are  exposed  at  the  earth  surface, where  lakes and streams intersect
shallow  water  tables,  and  where  there is concentrated agricultural,
industrial,  or  municipal   land  use.   Groundwater discharge can occur
because of vertical  leakage along faults or other boundaries.
     C.4.2  Surface Methods of Estimating Hydrologic Properties
Indirect  surface  methods can often be used to provide qualitative data
on  subsurface hydrologic properties.  These methods include:   (1)  earth
resistivity, (2) remote sensing,  and (3)  soil  and geologic surveys.
          C.4.2.1  Earth Resistivity


Earth  resistivity  surveys  are  useful   in  determining  shallow water
tables.   These  and  other  geophysical,   geochemical,   and  geological
surveys are reviewed by Maxey [30].   Resistivity surveys are inexpensive
and yield qualitative subsurface data.


          C.4.2.2  Remote Sensing
Remote  sensing  by  aerial  and  satellite  photography  can be used to
estimate   subsurface   hydrologic  properties  from  interpretation  of
differences  in  vegetation,  soil  associations,  and surface drainage.
Aerial  photographs  are  usually available from the SCS soil  surveys or
from  land use surveys.  Satellite photography,  a more recent technique,
and computer-generated maps can be used to estimate subsurface hydrology
from interpretation of surface features,  such as soil  moisture.
                                  C-32

-------
          C.4.2.3  Soil and Geologic Surveys


Existing  soil  surveys  often include information on geologic features,
depth  to groundwater, and areas of poor drainage.  Geologic surveys,  as
developed  by USGS, include discussions of climate, land use, geography,
ohysical  geology, mineralogy, petrology, structural geology, historical
geology,  paleontology,  and  economic  geology  of an area.  Methods  of
making  geologic  surveys  are discussed by Lahee [31] and Compton [32].
Geologic  surveys often include numerous measurements of rock thickness,
texture,  structure,  attitude  (dip,  strike,  plunge), and statistical
analysis of the data may be given.
Published  geologic  surveys are useful in describing location, physical
make-up, thickness, attitude, and boundaries of geologic units which may
be  aquifers.   They  are  useful  in identifying recharge and discharge
areas,  subsurface  flow  directions,  surface  drainage patterns, water
quality  problems,  and  potential  hazards  for  land use.  Surveys are
produced  by  federal and state geological surveys and bureaus of mines.
They  are also available as reports for special engineering, scientific,
and educational studies at universities and research centers.
     C.4.3  Subsurface Methods of Estimating Hydrologic Properties


Logging  methods,  aquifer  tests,  and  laboratory  tests are among the
subsurface methods used to estimate hydrologic properties.  They require
physical access to the subsurface through wells, pits, or drill  holes.


          C.4.3.1  Logging Methods
Logging  methods are used to estimate texture, porosity, and groundwater
circulation  and quality.  A log is a description of material  properties
with  depth as determined by observations or measurements through a hole
or  with  samples from a hole.  Drillers' logs and electrical  resistance
and  potential logs are most common.  Changes in soils or soil  materials
can  be  correlated  with spikes or peaks on the electric log  printouts.
Various  logging  methods  are  reviewed by Jones and Skibitzke [33] and
Todd  [34].  Professional logging companies publish detailed manuals and
research  papers.   A summary of subsurface logging information obtained
by various methods is provided in Table C-4.
          C.4.3.2  Aquifer Tests
Aquifer tests by the  pumped-well method are performed using a series of
wells in the field.  The approach is to discharge (purnp) or recharge one
well  at a known rate and to measure the response of water levels in the
                                  C-33

-------
other   wells.    Water level  responses  are then mathematically related to
permeability (  K )  or transmissivity [6].
                                   TABLE  C-4

                       SUBSURFACE LOGGING INFORMATION
                      OBTAINED BY VARIOUS METHODS  [34]
      Method
      Operation
             Information
 Drillers' log
Observe well cuttings
during drilling
 Drilling-time log  Observe drilling time
 Resistivity log   Measure electrical
                 resistivity of madia
                 surrounding encased hole
 Potential log


 Temperature log
 Caliper log

 Current log
Measure natural
electric potentia, or
self-potential
Measure temperature
Measure hole diameter


Measure current
 Radioactive log   Measure attenuation of
                 gamma and neutron rays
Rock contacts, thickness, description,
or type texture.  Samples for laboratory
tests.  Common method.

Rock texture, porosity.

Specific resistivity of rocks, porosity,
packing, water resistivity, moisture content,
temperature, groundwater quality.  Correlate
with samples for  best results.  Common method.

Permeable or impermeable,groundwater quality.
Common method.
Groundwater circulation, leakage.
Hole diameter, rock consolidation, caving
zones, casing location.

Groundwater flow velocity, circulation,
leakage.

Consolidation, porosity, moisture content.
Common in soil studies, clay or nonclay materials.
Bouwer   summarized    other   variations    including   the   auger-hole,
piezometer,   and tube  methods [35].   In the tube method, the  resultant K
is   for the  vertical direction  [25,  35].  For the piezometer  method, the
direction  of measured  K  depends on the ratio of  the piezometer height
to   its  diameter.   The  auger-hole  test,  which  measures  principally
horizontal permeability, is discussed further in Section C.5.2.2.
           C.4.3.3  Laboratory Tests
Laboratory   tests  of   subsurface  flow   properties  are generally not  as
reliable  as  field methods because of the  errors  introduced  in sampling
and the change in properties  due  to disturbance in sampling.   Laboratory
determinations  of  soil-water   characteristics  and unsaturated conduc-
tivity curves  are  presented  in  Taylor  and Ashcroft [1],  Kirkham and
Powers [3],   Black [36],   and  Bouwer  and  Jackson [37].   Because of the
tremendous   variability  of   actual  hydrologic properties, a great many
laboratory  tests must  be  conducted to provide statistical  validity.
                                       C-34

-------
C.5  Groundwater Mound Height Analysis


     C.5.1 • Introduction
If water that infiltrates the soil and percolates vertically through the
zone  of  aeration  encounters  a water table or an impermeable (or less
permeable)  layer,  a  groundwater  "mound"  will begin to grow.   If the
mound  height  continues to grow, it may eventually encroach on the zone
of aeration to the point where renovation capacity is affected.  Further
growth  may  result  in intersection of the mound with the soil surface,
which  will  reduce  infiltration  rates.   This  problem can usually be
identified  and  analyzed before the system is designed and built if the
proper geologic and hydrologic information is available for analysis.


Parizek  [20]  and  Spiegel  [38]  support  the concept of hydrogeologic
systems  analysis  to  define the probable effects of a project on local
and  regional  water  table configurations.  Modeling may be expected to
delineate  areas  likely  to  be  flooded,  demonstrating  the  need for
drainage  facilities  and  their  location.   Thus, contingency plans to
eliminate  potential  drainage  problems  can  be formulated at the time
projects are designed.
Practically  all  analyses of drainage problems have been limited to the
behavior of the water table, which of course responds to a wetting event
as  shown  in  Figures C-17 and C-18.  Irrigation experts recognize that
water  table  position  alone  is  not a satisfactory criterion in their
work.   If  the present state of knowledge would permit, they might well
redirect their attentions to the moisture content of the root zone.  The
situation  is  similar  with  respect to land application of wastewater.
One  is really less interested in the position of the water table at any
time  than  in  the  onset  of  anaerobiosis  in  the soil voids and the
breakdown of renovation capacity.  Analysis of the latter is so complex,
however,  that  we  will have to be content for the present to simply be
able  to control the water table, or to know how high it will rise under
given loading conditions.


Analysis  of  the growth and decay characteristics of groundwater mounds
induced by percolating waters is a complex, mathematically sophisticated
process.  The  problem  has  been  attacked  in  several ways, including
analytical,  analog,  and digital modeling.  Several empirical equations
representing gross approximations have also appeared.  A complete review
of  all the work in this area is well beyond the scope of this appendix.
Rather,  the  input  data  generally  required  for the analysis will be
discussed, and a short review will be provided of published studies that
should  prove  useful   to  the  user  searching  for  a method to suit a
particular  problem.   Only simple geometries, known to recur frequently
in practical applications, are covered by these references.
                                   C-.35

-------
                      FIGURE C-17



   MOUND  DEVELOPMENT FOR STRIP  RECHARGE  [33]





   AXIS  OF  SYMMETRY



   SURFACE  OF SPREADING  BASIN
•'•:^-V-V-'V:'"^''"'V..r/.'."'";-'* -'• \V*-V^'^I^<^*^'*O^* v'->^7-:'^^^
.%>'•»'. r.•.••'••'•'••*.•" ••-!.:*!- *:: C^^-":-!•:•.'t ^;xv.^-C'L"V».\ta>C*-i'-."""-X*.*i-i-:."r>.••••"•: .«••^l'*,vr:--.".-v\-'-..'.;-;-,:;>/.V%''.-.'.•..'{:
                    IMPERVIOUS  STRATUM
                      FIGURE C-18



   MOUND  DEVELOPMENT FOR CIRCULAR  RECHARGE AREA
                 RADIUS  OF  CIRCULAR

                 SPREADING  GROUNDS
                     SURFACE OF SPREADING BASIN
                                            UNDISTURBED GROUNDWATER

                                                   SURFACE
                                       IMPERVIOUS  STRATUM
                                                                         ~ W ^r
                           C-36

-------
     C.5.2  Data Requirements
Before  proceeding  with  any  analysis,  a  good  deal   of data must be
collected.   The  following  list  of  input information requirements is
abstracted  from  the  work of Baumann [39] and Parizek  [20].   Pertinent
comments  by  other  investigators  are  included  where  appropriate to
provide additional insight or clarification.
     1.   Coefficients  of vertical  and horizontal  permeability.   If the
          site  is  large  and/or  its  soils  heterogeneous,  a  spatial
          distribution  of  these values will be needed.  Klute [40] and
          Papadopulos  et al. [41]  both  stress  the need for extensive
          rather   than   intensive  methods  of  characterization,   and
          meaningful   average  conductivity  functions,  together  with
          probability statements as to deviations from the mean value.

     2.   Specific  yield  (drainable porosity)  of deposits saturated or
          dewatered by water table fluctuations.

     3.   Vertical  distances  between  initial   groundwater surface and
          ground  surface,  and  between initial groundwater surface and
          impervious stratum.

     4.   Slope of impervious strata.

     5.   Horizontal distance to a control  or discharge surface.

     6.   Geometry of recharge area.

     7.   Rate and duration of spreading (infiltration).  Although most,
          if not all, of the analytic expressions assume a steady supply
          (constant vertical  percolation),  Childs has shown that seepage
          of a series of intermittent recharges  is equivalent to  that of
          a single steady application [42].

     8.   Estimates of the evapotranspiration losses for the areas where
          groundwater tables will be near the surface.


          C.5.2.1   Drainable Voids
The  term  drainable  voids is synonymous with the term "specific yield"
used in water well technology.  It is the ratio of water that will drain
freely  from the materials to the total  volume of the materials.   It may
be estimated from data on similar soils (Table C-5), or more preferably,
it  may  be  evaluated  in  the  laboratory  from  soil moisture  data at
saturation and 0.3 bar tension on undisturbed soil fragments.
                                  C-37

-------
                                TABLE C-5

               APPROXIMATE DRAINABLE VOIDS FOR MAJOR SOIL
                            CLASSIFICATIONS
Material Porosity, %
Clay
Sand
Gravelly sand
Gravel
45
35
20
25
Drainable
voids, %
3
25
16
22
In  some  areas  of the United States,  the  SCS  has investigated the  soil
profile sufficiently to provide a reasonable  estimate of drainable voids
on  a  particular  site.  An outstanding  reference, covering 200 typical
soils   in   23  states,  is  the  USDA  Agricultural   Research  Service
Publication  41-144  [2].  This compendium  of soil-moisture tension  data
gives  bulk density, total porosity,  and  saturated vertical  permeability
values.   It also gives soil moisture at  0.1,  0.3, 0.6,  3.0, and 15  bars
tension  for  several   depths in the  soil profile (down  to about 4 ft or
1.2 m in many cases).
Drainable  voids  can  be  calculated  as   the   difference between  total
porosity  and  the volume percent of moisture at 0.3 bar tension.   Other
important  hydrologic  computations  can  be  made  as  well,   using  the
relationships  in Holtan et al.  [43].  One important factor that was  not
discussed  in  either  Reference  [2]  or   [43]  was the inherent spatial
variability  of  the  basic  measurements   reported.    Nielsen et  al.
conducted  a set of experiments  on a 370 acre (150 ha) site to determine
the  statistical   variability of  many soil  properties  affecting  its
hydrologic  behavior  [44].  A few of their results, shown in  Table C-6,
should be of value in developing a sensitivity for this variability.
          C.5.2.2  Lateral  (Horizontal)  Flow
Horizontal  permeability  is  a  more  difficult parameter to obtain.  In
field  soils, isotropic conditions are rarely  encountered, although  they
are  frequently  assumed  for  the  sake   of    convenience.    "Apparent"
anisotropic permeability often occurs in  unconsolidated media because  of
interbedding  of  fine-grained  and  coarse-grained materials within the
profile.  Such interbedding restricts permeability to vertical  flow  much
more  than  it  does  lateral  flow  [25].   Although  the  interbedding
represents  nonhomogeneity,  rather  than anisotropy, its effects on the
                                 C-38

-------
permeability  of  a large sample of aquifer material may  be  approximated
by   treating   the   "aquifer"  as  homogeneous  but   anisotropic.   A
considerable  amount  of data is available on the calculated or measured
relationships  between vertical and horizontal permeability  for specific
sites.   The  possible spread of ratios is indicated in Table C-7, which
is  based  on field measurements in glacial outwash deposits (Sites 1-5)
by  Weeks [45] and in a river bed (Site 6) by Bouwer [46].   Both  authors
claim,  with justification, that the reported values would not likely be
observed  in  any  laboratory  tests  with small quantities  of disturbed
aquifer material.
                                TABLE C-6

                   STATISTICAL VARIABILITY OF SEVERAL
                    PHYSICAL PROPERTIES OF SOIL  [44]
                                              Standard  Coefficient of
           Property     No.  of samples    Mean      deviation   variation, %


         Bulk density        720      1.356 g/cm3  0.104 g/cm3     7.7

         Moisture at
         saturation,
volume fraction
Moisture at
.200 cm tension
120
120
0.469
0.346
0.035
0.072
7.5
20.8
It  is apparent, then, that if accurate information regarding  horizontal
permeability  is  required  for  an analysis, field measurements will  be
necessary.  Of the many field measurement techniques available, the most
useful  is  the  auger  hole  technique  of  Van Bavel  and Kirkham [47].
Although  auger hole measurements are certainly affected  by  the vertical
component   of  flow,  studies  have  demonstrated  that  the  technique
primarily  measures  the horizontal component [48].  A  definition sketch
of  the  measurement system is shown in Figure C-19 and the  experimental
setup  is shown in Figure C-20.  The technique is based on the fact that
if  the hole extends below the water table and-water is removed from  the
hole  (by bailing or pumping), the hole will refill at  a  rate  determined
by  the  permeability  of  the soil, the dimensions of  the hole, and  the
height of water in the hole.  With the aid of either formulas  or graphs,
the  permeability is calculated from measured rates of  rise  in the hole.
The  total  inflow into the hole should be sufficiently small  during  the
period of measurement to permit calculation of the permeability based on
an "average" hydraulic head.  This is usually the case.
In  the  formulas and graphs that have been derived,  the  soil  is  assumed
to  be  homogeneous and isotropic.  However, a modification  of the  basic
technique  by  Maasland  allows  determination  of  the   horizontal   and
                                   C-39

-------
vertical   components (Kn and  KV)  in anisotropic  soils by combining  auger
hole  measurements  with piezometer measurements  at the same depth  [48].
If  the   auger  hole  terminates   at  (or  in) an impermeable  layer,  the
following equation applies  (refer to Figure C-19  for symbols):
                       Kh  =  523 000 a2                             (C-7)
where   a  =  auger hold radius,  m
      At  =  time for water  to  rise y, s
       Kh  =  horizontal permeability,  m/d
  yQ, y1.=  depths defined  in  Figure  C-19, any units, usually cm


If an  impermeable layer is  encountered at a great  depth below the  bottom
of the  auger hole, the equation becomes

                      K  _  1 045 OOP  da2      ^g^W
                       h "   (2d + a)               At(C"b)
where  d  =  depth of auger hole, m

                                   TABLE  C-7

                      MEASURED RATIOS  OF HORIZONTAL TO
                            VERTICAL PERMEABILITY
                  Effective horizontal
           Site  permeability,  Kh ,  ft/d  Kh/Kv         Remarks
1
2
3
4
5
6
138
247
183
329
237
236
2.0
2.0
4.4
7.0
20.0
10.0
Silty


Gravelly
Near terminal moraine
Irregular succession of sand





and
                                          gravel layers (from  K measure-
                                          ments in field)

                        282          16.0   (From analysis of recharge
                                          flow system)
           a. Sources:  Data on Sites 1  through 5  [45];  data on Site 6 [46].

           1 ft/d = 0.305 m/d
                                    C-40

-------
                         FIGURE C-19

        DEFINITION SKETCH  FOR AUGER-HOLE TECHNIQUE
                                       SOIL SURFACE
:".v'W--!v"

I



• K:''-.-:-'.!_

y



!*•".•*
1
y
0
i

;h

•*.'*•*'.
[
i





«, 	 2a 	 »


^"^

WATER TABLE

_!_
^y in. At
t
1
       1 in. = 2.54 cm

                         FIGURE C-20

       EXPERIMENTAL SETUP  FOR AUGER-HOLE TECHNIQUE
              DOUBLE-ACTING
             DIAPHRAGM PUMP
MEASURING POINT


   STANDARD
EXHAUST HOSE
                   TAPE  AND
                   2 in.FLOAT
                                              STATIC WATER LEVEL
  FINISH  TEST
                                              START TEST
        1  in.= 2.54 cm
                            C-41

-------
Charts  for  both  cases were prepared by Ernst and are available in the
text  by Luthin [49].  An alternate formula,  claimed to be slightly more
accurate,  has been developed by Boast and Kirkham [50];.   Their equation
employs  a  table of coefficients to account  for depth of impermeable or
of very permeable material below the bottom of the hole.
There   are   several   other   techniques   for  evaluating  horizontal
permeability  in  the  presence  of  a water table.  Slug tests, such as
described  by  Bouwer  and  Rice, can be used to calculate  K^  from the
Thiem  equation  after  observing  the  rate  of rise of water in a well
following  an  instantaneous  removal  of  a volume of water to create a
hydraulic  gradient  [51].   Certainly  pumping tests, which are already
familiar to many engineers, would provide a meaningful estimate.  Glover
presents  a  comprehensive discussion of pumping tests, as well as other
groundwater  problems.   He also presents example problems and tables of
the mathematical functions needed to evaluate permeability from drawdown
measurements [52].
There are two limitations to full-scale pumping tests.   The first is the
expense  involved  in drilling and installation.   Thus,  if a well  is not
already  located  on the site, the pumping test technique would probably
not  be  considered.   If  an  existing  production  well  fulfills  the
conditions  needed  for the technique to be valid, it should probably be
used  to  obtain  an estimate.  However, this estimate may still  require
modification  through  the  use of supplementary  "point" determinations,
especially  if  the  site  is  very  large  or  if  the   soils are quite
heterogeneous.   The  possibility  that  the  pumping test will  not give
results representative of the larger area is the  second  limitation.


Donnan  and  Aronovici  developed a technique using a small well  screen,
carefully  manufactured  to  a  set  of  standard  specifications  [53].
Because  these  screens  have  a constant and reproducible flow geometry
when inserted below the water table and pumped, standard curves prepared
by  the  authors  could  be  used  to  compute   K.   from  flowrate  and
pressure drop data.


Measurement  of horizontal and vertical permeabil ity may occasionally be
necessary in the absence of a water table.  A typical case might involve
the  presence  of  a  caliche layer, or other hardpan formation near the
surface,  which  is  restrictive  enough to vertical flow to result in a
perched  water  table  upon  application  of  effluent.    In  this case,
equipment   and   techniques   developed   by  Bouwer will  permit  the
determination [54],  The required equipment is known as  the Tempe Double
Tube Hydraulic Permeability Device.  Water levels in the inner and outer
tube  are  manipulated  to  give as estimate of the overall permeability
which  is some resultant  of  Kn  and  Kv  (more   of   Kv ).   The  true
value  of  Kh  can  be  evaluated by inserting piezometers in the double
tube  system  to  measure  the  true  Kv .   Kn  can  then  be computed.
Other  methods  for  measuring  K in absence of water table are:  shallow
well  pump-in   method  ( Kh  ),  air  entry  permeameter (Kv )  and in-
filtration gradient method  ( Kv )  [4].
                                  C-42

-------
     C.5.3  Models for Two Geometries of Practical Concern
Two  recharge  area  geometries  can  be expected to recur frequently in
practice.   The   first   involves  a  rectangular  area  lying  roughly
perpendicular  to  the  initial  direction  of groundwater flow.  If the
length  is  large  relative  to  the width, the area can be considered a
strip  and  the  resulting  mound  will  be two-dimensional, as shown in
Figure C-17.
The  growth and decay of the two-dimensional mound is given analytically
by both Baumann [39] and Marino [55].  Baumann based his solution on the
analogy  of  the  flow  of heat through a prismatic, nonradiating bar of
length  L.  with  a  constant heat source   v   at the origin (X = 0) and
constant  temperature  at  X  =  Lj.    The exact solution for the stable
mound  at  t  = °o is a Fourier-series expansion; however, an approximate
solution  for the mound coordinates can be obtained more simply from the
expression
                               (Ld -
                                              X)
                         (C-9)
where v = the average infiltration rate
      i  = the slope of the impermeable strata, usually zero
This expression allows calculation of the mound height at either edge of
the  spreading  basin.   The  maximum  height  H  ,  at the center of the
strip, would have to be estimated from the geometry  and the shape of the
curve near X = 0.
If the spreading area can be readily approximated by a circle, the mound
will  be  three-dimensional.   The  absence  of  a  circular control  for
lateral flow makes the problem of defining a stable mound difficult,  but
solutions  are  available  [39,  56,  57].   Referring to the definition
sketch  shown  in Figure C-18, one solution for the maximum mound height
(from reference [57]) is
H=^
    y
                              -u
               1
               1 - e
+ u
                                              du
                                                               (C-10)
 where  u
= R2/4«t
        a =  Kd/y
       .y =  drainable
            void volume
                                  C-43

-------
and the integral above is the well-known exponential  integral, values of
which  are  tabulated  in  reference  [52].    Graphical  solutions to the
equations  of  groundwater  mound  height analysis for several important
geometries  may  be found in reference [58],  a publication of the USDA -
Agricultural Research Service.


C.6  Control of the Groundwater Table
The  need  for  drainage  will   be  established  through  some method of
groundwater  mound  height  analysis or when the  natural  fluctuations in
the  groundwater table are thought to bring it too close to the surface,
the  latter  being  a judgment of the designer.  For some large projects
that  do  not  require a complete system of underdrainage, drainage at a
few  selected  locations  may be required.   For other projects, drainage
may  be  required  only to prevent trespass of wastewater onto adjoining
property by subsurface flow.
The  drainage  design  consists  of  selecting  the depth and spacing  for
placement  of  the  drain  pipes  or  tiles.    As  a frame of reference,
practical drainage systems for wastewater applications will  be at depths
of 4 to 8 ft (1.2 to 2.4 m), at or in the water table, and spaced 200 ft
(60 m)  or  more  apart.   Spacing  may approach 500 ft (150 m)  in sandy
soils.   Although  closer spacings result in  better control  of the water
table,  the  cost  of  moving  the  drains closer together soon becomes
prohibitive except for a very few cases.
A definition sketch-for the use of the Hooghoudt drain spacing  method is
shown  in  Figure C-21.   The  assumptions  of this method are as  follows
[49]:

     1.   The  soil   is  homogeneous and of permeability   K  (horizontal
          conductivity).

     2.   The drains are evenly spaced a distance  S  apart.

     3.   The  hydraulic  gradient at any point is equal  to the slope of
          the water table above that point.

     4.   Darcy's law is valid.

     5.   An impermeable layer underlies the drain at a depth  d  .

     6.   The rate of replenishment (wastewater application plus  natural
          precipitation) is  v .
                                   C-44

-------
                                FIGURE C-21

                DEFINITION SKETCH FOR DRAIN SPACING FORMULA



                           APPLICATION RATE V, in./h

               11111111111
                                                    SOIL SURFACE
                                                  WATER TABLE
                                IMPERMEABLE  LAYER
            1  in./h = 2.54 cm/h
Omitting  all   details   of   the  derivation,  the final  spacing formula is
given as
S2 =
                                      (2d + H)
                                                              (C-ll)
where H is the maximum  height  of water  table  allowable above the drains.


This  equation  is  approximate,   and several  modifications are possible
and/or  necessary  for  particular field  situations.   In particular,  the
value  of  d in Equation C-ll  is only equal to the  actual  depth when  the
depth • is small.  Hooghoudt developed a table  of  "equivalent"  depths  for
large values of d  which are to be substituted for  the actual  value of d
in  Equation C-ll.    Curves based on Hooghoudt1s analysis are available
in  Luthin's  text  [49].   Additional details of drainage design may be
found  in  Luthin  and  other references (see Section  C.8).  On occasion,
pumped  wells  have  been used for drainage and/or  recovery of renovated
effluent  when  the  water  table   is too deep for  the use of  horizontal
drains [46].
                                    C-45

-------
C.7  Relationship   Between   Measured  Hydraulic  Capacity  and  Actual
     Operating Capacity
The   relationship   between  measured  hydraulic  capacity  and  actual
operating   capacity   is   an  extremely  important  subject  which  is
complicated by the fact that meaningful  data are not generally available
for  analysis.  In addition, not every site is hydraulically limited;  in
fact,  most  sites  probably  are  not.    In  many  cases,   loadings are
controlled   by  management  approaches,  nitrogen  loadings,  or  other
factors.   However,  for  sites  that  receive  relatively   low  organic
loadings  (say  less  than  200 lb/acre-d [224 kg/ha-d]  of  BOD) and that
have  no  other  limiting  factors,  it would be significant to know the
relationship  between  the highest hydraulic loadings that  did not cause
problems  and  the  original  infiltration  rates  measured on the soils
before  the initial applications of wastewater began.  Data from several
systems  are  summarized  in Table C-8,  but they are from a very limited
cross-section  of soil types and wastewater characteristics, so it would
be  inappropriate  to  draw general conclusions from them.   More data of
this  type  are required before a meaningful pattern can emerge.  As can
be  seen from the footnotes, only two of the systems are being loaded at
or  near their maximum acceptance rate in the absence of any other known
constraints.   Such  situations make data interpretation very difficult.
At  present,  it  appears  that loadings in the range of 5  to 25% of the
measured  infiltration rate will generally produce a satisfactory result
in terms of system hydraulics, no other constraints existing.  Operating
rates  reported  in  Table  C-8  are calculated using total  cycle times,
including the time allowed for resting and drying.  One  further point of
interest is the hydraulic loading for the Flushing Meadows  project which
averages  about 25% of potential infiltration.  It is believed that this
may  be  the peak value (as a percentage) attainable anywhere because of
the nearly ideal conditions at the Phoenix test site [24],

                                TABLE C-8

          SUMMARY OF MEASURED INFILTRATION RATES AND OPERATING
            RATES FOR SELECTED LAND APPLICATION SYSTEMS  [59]
System Soil texture
type class' Type of wastewater
Slow rate Silt loam Steam peel potato
Slow rate Loam Secondary effluent meat packing
Slow rate Silt loam Secondary municipal
Rapid infiltration Sand Oily cooling water
Rapid infiltration Gravelly sand Secondary kraft mill
Rapid infiltration Loamy sand Secondary kraft mill
Rapid infiltration Sand gravel Secondary municipal
a. Limited by poor drainage (high water table).
b. Limited arbitrarily to irrigate larger acreage for hay production
c. Limited by nitrogen loading considerations.
d. Limited by organic loading (biological clogging problems).
Infiltration
rate I, in./h
0.8-0.9
0.8-2.10
0.2-0.3
9.0-14.4
28.0-55.0
1.5-9.7
8.8-11.8




Operating
rate v , in./h
0.03a
0.03b
0.01C
2.8
0.29d
0.1 9d
0.55





v/I, %
03.4
1.4-3.8
4.0
19.0-31.0
0.5-1.0
2.0-12.7
4.6-6.2




  1 in./h = 2.54 cm/h
                                   C-46

-------
C.8 References
 1.  Taylor,- S.A.  and  G.L.    Ashcroft.    Physical    Edaphology.    San
     Francisco, W.H. Freeman & Co.   1972.

 2.  Hoi tan,  H.N.,  et al.   Moisture-Tension Data  for Selected Soils on
     Experimental  Watersheds.   U.S.  Dept.  of Agriculture,  Agricultural
     Research Service.  Publication No.  41-144.   1968.

 3.  Kirkham,  D.  and  W.L.  Powers.   Advanced Soil  Physics.   New  York,
     Wiley-Interscience.  1972.  534.p.

 4.  Klute,  A.   The  Movement  of  Water  in  Unsaturated   Soils.   In:
     Proceedings  of  the  First  International   Seminar  for  Hydrology
     Professors, the Progress of Hydrology,  Vol. 2.   July 1969.  pp  821-
     888.

 5.  Todd,  O.K.   Groundwater.   In:    Handbook of   Applied Hydrology.
     Chow, V.T. (ed.).  New York, McGraw-Hill Book  Company.   1964.

 6.  Musgrave,  G.W.  and  H.N. Holtan.   Infiltration.  In:   Handbook of
     Applied  Hydrology.   Chow, V.T.  (ed.).  McGraw-Hill Co.   1964.   pp
     12-1 to 12-30.

 7.  Parr,  J.F. and A.R. Bertrand.  Water Infiltration Into Soils.   In:
     Advances  in  Agronomy.   Norman,  A.G.  (ed.).   New York, Academic
     Pres-s.  I960,  pp 311-363.

 8.  Bouwer^ H.  Infiltration of Water Into  Nonuniform Soil. ~Journal  of
     the Irrigation and Drainage Div., ASCE.  95(IR4):451-462,  1969.

 9.  Bouwer,   H.   Infiltration  Into  Increasingly    Permeable Soils.
     Journal  of  Irrigation and Drainage  Division, ASCE. 102(IR1):127-
     136, 1976.

10.  O'Neal,  A.M.   A  Key for Evaluating Soil  Permeability by Means of
     Certain Field Clues.  Soil Sci. Soc.  Amer.  Proc.  16:312-315,  1952.

11.  Burgy, R.H. and J.N. Luthin.  A Test  of the Single- and Double-Ring
     Types  of Infiltrometers.  Trans. Amer. Geophysical Union.  37:189-
     191, 1956.

12.  Manual  of  Septic-Tank  Practice.    U.S.  Public  Health  Service.
     Publication No. 526.  U.S. Gov't Printing Office, 1969.

13.  Wallace,  A.T.,  et  al.   Rapid Infiltration Disposal of Kraft Mill
     Effluent.    In:    Proceedings   of    the  30th  Industrial   Waste
     Conference, Purdue University, Ind.  1975.

14.  Tovey,  R. and C.H. Pair.  A Method for Measuring Water Intake  Rate
     Into  Soil for Sprinkler Design.   In:  Proceedings of the Sprinkler
     Irrigation Association Open Technical Conference.  1963.
                                    C-47

-------
15.  Haise,  H.R.,  et  al.    The  Use  of  Cylinder  Infiltrometers   to
     Determine  the  Intake   Characteristics  of  Irrigated Soils.  U.S.
     Dept.  of  Agriculture, Agricultural  Research Service.  Publication
     No. 41-7.  1956.

16.  Hills,  R.C.   Lateral   Flow  Under  Cylinder   Infiltrometers:    A
     Graphical Correction Procedure.   Journal  of Hydrology.  13:153-162,
     1971.

17.  Swartzendruber,  D. and T.C. Olson.  Model  Study of the Double-Ring
     Infiltrometer  as  Affected  by  Depth of  Wetting and Particle  Size.
     Soil  Science.  92:219-225,  April  1961.

18.  Bouwer,  H.  Unsaturated  Flow  in  Ground-water  Hydraulics.    In:
     Proceedings   of   the    American   Society  of  Civil Engineers.
     90:HY5:121-141, 1964.

19.  Van  Schilfgaarde,  J.   Theory of Flow to Drains.   In:  Advances in
     Hydroscience.   Chow, V.T.  (ed.).  New York,  Academic Press.   1970.
     pp 43-103.

20.  Parizek,  R.R.   Site   Selection Criteria for Wastewater Disposal  -
     Soils  and  Hydrogeologic  Considerations.    In:  Recycling Treated
     Municipal  Wastewater   and  Sludge  Through  Forest  and  Cropland.
     Sopper,  W.E. and L.T.  Kardos (eds).   Pennsylvania State University
     Press.  1973. pp 95-147.

21.  Musgrave,  G.W.   The  Infiltration Capacity of Soils in Relation to
     the Control of Surface  Runoff and Erosion.   Journal  of the American
     Society of Agronomy. 27:336-345, 1935.

22.  Ongerth, J.E. and S. Bhagat.  Feasibility Studies  for Land Disposal
     of  a  Dilute  Oily  Wastewater.    In:    Proceedings  of  the  30th
     Industrial Waste Conference, Purdue University, Ind.  1975.

23.  Thompson,  J.   Aluminum  Co. of  Amer.,  Inc.,  Wenatchee,   Wash.
     Personal Communication, 1976.

24.  Bouwer,  H.   U.S.  Water  Conservation  Laboratory, Phoenix,  Ariz.
     Personal Communication, 1977.
                 s~

25.  Bouwer,  H.   Planning  and Interpreting  Soil Permeability Measure-
     ments.  Journal of the  Irrigation and Drainage Division, ASCE.   28:
     (IR3):391-402, 1969.

26.  Bouwer,  H.  Measuring  Horizontal  and Vertical  Hydraulic Conduc-
     tivity of Soil With the Double Tube Method.   Soil  Sci.  Soc.   Amer.
     Proc.  28:19-23,  1964.

27.  Bouwer,  H.  and R.C. Rice.  Modified Tube-Diameters for the Double
     Tube Apparatus.  Soil Sci.  Soc.  Amer. Proc.  31:437-439, 1967.
                                  C-48

-------
28.  Black,  C.A.   (eel.).   Methods of Soil  Analysis, Part I:   Physical
     Properties.   Agronomy  9,  American Society of Agronomy.   Madison.
     1965.

29.  Bouwer,   H.   Rapid  Field  Measurement  of  Air-Entry  Value  and
     Hydraulic  Conductivity  of  Soil  as Significant Parameters in Flow
     System Analysis.  Water Resources Research.  2:729-738, 1966.

30.  Maxey,  G.B.   Geology:   Part  I - Hydrogeology.  In:  Handbook of
     Applied  Hydrology.   Chow, V.T. (ed.).   New York, McGraw-Hill Book
     Company. 1964.

31.  Lahee, F.H.  Field Geology.  Fourth edition.  New York, McGraw-Hill
     Book Company.  1941.

32.  Compton,  R.R.   Manual  of  Field Geology.  New York, John Wiley &
     Sons. 1962.  230 p.

33.  Jones,  P.H. and H.E. Skibitzke.  Subsurface Geophysical  Methods in
     Groundwater  Hydrology.   In:   Advances  in  Geophysics,   Vol.   3,
     Landsberg, H.E. (ed.).  New York, Academic.  1956.  pp 241-300.

34.  Todd,  O.K.   Groundwater  Hydrology.  New York, John Wiley &  Sons.
     1959.  336 p.

35.  Luthin,  J.N.  (ed.).   Drainage  of  Agricultural Lands.   Madison,
     American Society of Agronomy.  1957.

36.  Black,  C.A.   (ed.).   Methods of Soil  Analysis, Part 2:   Chemical
     and  Microbiological  Properties.   Agronomy 9, American Society of
     Agronomy, Madison.  1965.

37.  Bouwer,  H.  and  R.D.  Jackson.  Determining Soil Properties.  In:
     Drainage  for  Agriculture.   Van  Shilfgaarde, J. (ed.).   Hadison,
     American Society of Agronomy.  Mongraph  No. 17.  1974.  pp 611-666.

38.  Spiegel,  Z.  Hydrology.  In:  Wastewater Resources Manual.  Norum,
     E.  (ed.).   Silver  Spring, Md.  Sprinkler Irrigation Association,
     1975.

39.  Baumann,  P.  Technical Developments in  Ground Water Recharge.  In:
     Advances  in  Hydroscience.   Chow, V.T. (ed.).  New York, Academic
     Press.  1965.  pp 209-279.

40.  Klute,  A.   The  Determination  of  the  Hydraulic Conductivity of
     Unsaturated Soils.  Soil Science.   113:264-276, April  1972.

41.  Papadopulos,  S.S.,  J.D.  Bredehoeft, and H.H. Cooper, Jr.  On  the
     Analysis  of  'Slug Test1 Data.  Water Resources Research.  9:1087-
     1089, 1973.


42.  Childs,  E.C.   The  Nonsteady  State of the Water Table in Drained
     Land, Journal of Geophysical Research.  65:780-782, 1960.
                                   C-49

-------
43.  Holtan,  H.N.,  et  al.    Hydrologic  Characteristics of Soil  Types.
     In:   Proceedings  of  the  American   Society  of  Civil  Engineers.
     93:IR3:33-41, 1967.

44.  Nielsen,  D.R.,  J.W.  Biggar,  and J.C.  Corey.   Application of Flow
     Theory  to  Field  Situations.    Soil   Science.  113:254-263,  April
     1972.

45.  Weeks,  E.P.   Determining  the  Ratio  of  Horizontal   to Vertical
     Permeability by Aquifer - Test  Analysis.   Water Resources Research.
      :196-214, January 1969.

46.  Bouwer,  H.   Ground  Water  Recharge  Design  for Renovating  Waste
     Water.    In:    Proceedings of  the  American  Society   of  Civil
     Engineers. 96:SA1:59-73, 1970.

47.  Van  Bavel,  C,.H.M.  and  D. Kirkham.   Field   Measurement of Soil
     Permeability Using Auger Holes.  Soil  Sci. Sco. Amer. Proc.  13:90-
     96, 1948.

48.  Maasland,  M.   Measurement  of Hydraulic  Conductivity  by the  Auger
     Hole  Method  in  Anisotropic  Soil.    Soil   Sci.  Soc. Amer.  Proc.
     19:379-388, 1955.

49.  Luthin, J.N.  Drainage Engineering.  Huntington, N.Y.,  R.E. Krieger
     Pub. Co. 1973.  First edition - reprinted  with  corrections. 250  p.

50.  Boast,  C.W. and D. Kirkham. Auger Hole  Seepage Theory.   Soil  Sci.
     Soc. Amer. Proc.  35:365-373, 1971.

51.  Bouwer,  H.  and  R.C.  Rice. A Slug  Test  for Determining Hydraulic
     Conductivity  of  Unconfined Aquifers With Completely  or Partially
     Penetrating Wells.  Water Resources Research.  12:423-428, 1976.

52.  Glover,  P.E.   Ground-water Movement.  U.S.  Bureau of  Reclamation,
     Water  Resources.   Technical Publication  Engineering Monograph No.
     31.  1966.

53.  Donnan,  W.W.  and  V.S. Aronovici.  Field Measurement  of Hydraulic
     Conductivity.   In:   Proceedings  of the  American Society of  Civil
     Engineers.  87:IR2:1-13, 1961.

54.  Bouwer, H.  Measuring Horizontal and  Vertical Hydraulic Conductivity
     of  Soil  With  the Double-Tube Method.   Soil Sci. Soc. Amer.   Proc.
     28:19-23, 1964.

55.  Marino,  M.A.   Growth  and  Decay of Groundwater Mounds  Induced by
     Percolation.  Journal of Hydrology.  22:295-301, 1974.

56.  Marino,   M.A.    Artifical  Groundwater   Recharge,  I  - Circular
     Recharging Area.  Journal of Hydrology.   25:201-208. 1975.
                                   C-50

-------
57.  Bianchi,  W.C.  and  E.E.  Haskell,  Jr.   Field Observations  Compared
     With  Dupuit-Forchheimer  Theory for Mound Heights Under a  Recharge
     Basin.  Water Resources Research.   4:1049-1057,  1968.

58.  Bianchi,  W.C.  and  D.C.  Muckel.   Ground-Water  Recharge Hydrology.
     U.S.   Dept.   of   Agriculture,   Agricultural   Research  Service.
     Publication No. 41-161, 1970.

59.  Wallace, A.T.  Personal Files.  October 1976.
                                  C-51

-------
                               APPENDIX D

                                PATHOGENS
D.I  Introduction
Because  land  treatment  must  be  compared  equitably  to conventional
wastewater  discharge  systems  in facilities planning, a need  exists  to
evaluate the relative health risks associated with land treatment versus
conventional systems.  Unfortunately,  there are few data on this aspect.
Since  the  level  of enteric disease  in the United States is relatively
low,  wastewater  in  the United States would be expected to contain low
levels  of pathogens compared with that in many regions of Asia, Africa,
and  South  America.   However,  the  continual  occurrence of waterborne
disease caused by wastewater-contaminated water in the United States [1]
indicates  that  sufficient  numbers  of  pathogens  are present to be a
public health concern.
D.2  Relative Public Health Risk
Sufficient  data are not available to show whether or not land  treatment
is  a  greater  health  risk  than  conventional  treatment and  discharge
systems.   The  paucity  of  information  available on disease  caused  by
wastewater  treatment  processes  may  reflect  either  the absence  of a
problem, lack of intensive surveillance, or the insensitivity of  present
epidemiological  tools  to  detect  recurrent  small-scale  incidents  of
disease.  It should be emphasized, however, that no incidents of  disease
have been documented from a planned and properly operated land  treatment
system.    Comparative  epidemiological  studies  on  human populations
associated  with  conventional   as  well  as  land treatment systems are
needed  to  provide  sufficient  and  reliable data on which regulations
could  be based.  Thus, evaluation of potential  health hazards  must  rest
on  our knowledge of the occurrence of pathogens in wastewater  and their
fate during land treatment.
D.3  Pathogens Present in Wastewater


A  large  variety  of  disease-causing  microorganisms and parasites  are
present  in  domestic  wastewater.   These  include pathogenic bacteria,
viruses,  protozoa,  and  parasitic  worms.   The  number  of individual
species  of pathogens is high.  For example, over 100 different types of
viruses  are  known  to  be  excreted  in  human  feces.    The  relative
concentrations  of  these pathogens are highly variable,  being dependent
on  a number of complex factors, but pathogens are almost always present
in  untreated  wastewater  in  sufficient  numbers to be  a public health
concern.  Thus, it is necessary to identify and put into  perspective  any
potential  routes  of disease transmission involved in land treatment as
                                  D-l

-------
well  as  conventional   treatment  of  wastewater   so   that   appropriate
safeguards  can  be  assured.    It  is   also  necessary  to  identify the
relative  risk  of infection for humans  and animals from  these  and other
sources.
Most  of  the  studies reported in this  appendix  involve  applications of
untreated  wastewater  (often  simply  referred to  as wastewater) to the
land  in  an  unplanned  manner,   or   deliberate  artificial   seeding of
bacteria  or  viruses  in  high  concentrations to  the  soil to determine
their survival  or movement under  various conditions.  Because  each study
had  different  objectives,  types of  soil, climatic  factors, types of
organisms,  and  methods  of  detection,  the results must be interpreted
accordingly.   In citing a particular  study for purposes  of establishing
safeguards  or  standards,  all of the conditions relevant to  that study
should  be  defined.    In general, safeguards should be established on a
case-by-case  basis so that the relative risk of  disease  transmission in
each situation can be evaluated individually.
     D.3.1  Bacteria
The  most common bacterial  pathogens  found  in wastewater  include  strains
of  Salmonella,  Shigella,   enteropathogenic Escherichia  coli  (E. coli),
Vibrio,  and  Mycobacterium.   The genus Salmonella  includes  over 1 200
different  strains,  many  of  which   are   pathogenic  for   both  man and
animals.   Members  of  this group are commonly  isolated  from  wastewater
and  polluted  receiving  waters.   Salmonella typhi has been responsible
for  incidents  of typhoid fever associated with wastewater-contaminated
drinking  water  [1] and with the eating of raw  vegetables grown  on soil
fertilized  with  untreated  wastewater [2].  Other members  of the group
are associated with paratyphoid fever and acute  gastroenteritis.
Shigella  organisms  are  the  most  commonly   identified  cause of acute
bacterial diarrhea! disease in the United States  [3].   Waterborne spread
of  the  organisms can cause outbreaks  of shigellosis,  commonly known as
bacillary dysentery, which occur frequently  in  undeveloped countries and
occasionally  in  developed   countries.   Unlike Salmonella.  Shi gel!a
organisms are rarely found in animals other  than  man.
Cholera  is  caused  by the organism Vibrio cholerae.   In  Israel  in  1970
cases of cholera were attributed to the  practice  of  irrigating  vegetable
crops   with  untreated   wastewater.    This   practice   is   contrary  to
regulations of the Ministry of Health [4],  There were  no  reported cases
of  cholera  in  the United States  between 1911 and  1973,  until a single
case occurred in Texas with no known source.   Though individual cases of
cholera  may arise in international  travelers, the likelihood of  cholera
being transmitted by wastewater land application  projects  is minimal.
                                   D-2

-------
     D.3.2  Viruses [5]
Viruses,  the  smallest  wastewater pathogens, consist of a nucleic acid
genome  enclosed in a protective protein coat.  Viruses that are shed in
fecal matter, referred to as enteric viruses, are characterized by their
ability  to infect tissues in the throat and gastrointestinal  tract, but
they  are also capable of replicating in other organs of the body.  They
include  the  true  enteroviruses (polio-, echo-, and coxsackieviruses),
reoviruses,  adenoviruses,  and  rotaviruses,  as  well  as the agent of
infectious  hepatitis.   These  viruses  can  cause  a  wide  variety of
diseases,   such   as   paralysis,   meningitis,   respiratory  illness,
myocarditis, congenital heart anomalies, diarrhea, eye infections, rash,
liver  disease,  and  gastroenteritis.  Almost all of these viruses also
produce  inapparent  or  latent  infections.  This makes it difficult to
recognize  them  as  being  waterborne.   Documented cases of waterborne
viral  disease have largely been limited to infectious hepatitis,  mainly
because  of  the  explosive  nature  of the cases and the characteristic
nature of the disease.
Knowledge  of  the  actual  number and concentration of human pathogenic
viruses  in  wastewater  is  inadequate,  due  to  lack  of adequate and
standardized  sampling  and  analytical  procedures.   Furthermore,  the
methodology  for  detecting  and monitoring many of these agents has not
yet been developed.  This probably accounts for the fact that almost 60%
of all documented cases of disease attributable to drinking water in the
United  States  has  been  reported  to  be  caused by agents as yet not
isolated  in  the  laboratory.   The  lack of documentation reflects the
difficulty in sampling an infectious agent in the carrier at the time of
reported  illness.  It must be borne in mind that viruses as a group are
generally more resistant to environmental stresses and chlorination than
pathogenic bacteria.
Also  present in wastewater are large numbers of bacterial viruses known
as  bacteriophages.   These viruses are not pathogenic for man, but they
have  been  studied  as  models for animal virus behavior because of the
ease with which they can be detected.  However, it should not be assumed
that  all  studies using bacteriophages can be directly applied to human
pathogenic viruses.
     D.3.3  Other Pathogens
Protozoans  pathogenic  to man and capable of transmission in wastewater
are Entamoeba histolytica, the agent  of  amoebic  dysentery;  Naegleria
gruberi, which  may cause fatal meningoencephalitis; and Giardia Iambi a,
which  produces  a  variety of intestinal symptoms.   Waterborne cases of
Giardia lamblia have increased in the United States  in recent years [1].
                                  D-3

-------
The  eggs   of  several  intestinal   parasitic  worms   have been found in
wastewater  and  have  been   shown   to  be a potential  health problem to
wastewater  treatment  plant  operators and laborers employed on farms in
India and  East Germany where  untreated wastewater is  used for irrigation
[6].   Modern  water  treatment  methods  have  proved  a very effective
barrier  against the waterborne  spread of disease caused by protozoa and
parasitic  worms in developed  countries, like the United States.
     D.3.4   Concentrations of Pathogens  in Wastewater
Evaluation   of the relative risk of  disease transmission  associated with
land  application  of  wastewater  requires  knowledge  of the number of
pathogens   in  untreated  and  treated wastewater, as well  as the number
necessary to cause an infection in man or other animals.   Unfortunately,
data  on  the removal efficiency of  all  wastewater treatment methods for
many  pathogens  are  either   nonexistent or largely based on laboratory