r/EPA
United States
Environmental Protection
Agency
Region 5
Water Division
230 South Dearborn Street
Chicago, Illinois 60604
March 1983
Technical Reference
Document 905R83108
Final-Generic
Environmental Impact
Statement
Wastewater Management
In Rural Lake Areas
-------
31 January 1983
TECHNICAL REFERENCE DOCUMENTS
Supporting the
Generic Environmental Impact Statement
for
Wastewater Management in Rural Lake Areas
Gerald 0. Peters, Jr.
Principal Investigator
WAPORA, Inc.
Chevy Chase, Maryland 20815
Contract No. 68-01-5989
Project Officer:
Jack Kratzmeyer
Environmental Impact Section
U.S. EPA, Region V
Chicago, Illinois 60604
MUNICIPAL FACILITIES BRANCH
REGION V
U.S. ENVIRONMENTAL PROTECTION AGENCY
CHICAGO, ILLINOIS 60604
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Table of Contents
Page
Title Page
Disclaimer
Foreword
Preparers
Contents
Chapter I - FACT SHEETS
1.1 - 1.6 Water Conservation I-A-1
2.1 - 2.9 On-Site Technologies I-A-12
3.1 - 3.9 Septage Handling, Treatment, and Disposal I-A-46
4.1 - 4.2 Small Scale Technologies I-A-62
Chapter II - EVALUATION AND DESIGN METHODOLOGIES
A. Water Quality Impacts of On-Site Systems II-A-1
B. The Role of Needs Documentation in Alternatives
Development II-B-1
C. Review of Direct and Remote Sensing Techniques II-C-1
D. Septic Leachate Detector Research II-D-1
E. Septic Leachate Detector Policy II-E-1
F. Aerial Photography Methods and Policy II-F-1
G. Sanitary Survey Methods and Policy II-G-1
APPENDIX A -
APPENDIX B - TM
H. Evaluation of the Dowser Groundwater Flow Meter II-H-1
I. Evaluation and Design of Off-Site Small Waste Flow
Technologies II-I-l
J. Site Analysis and Technology Selection for On-Site
Systems II-J-1
K. Geotechnical Investigations for Cluster Drainfields II-K-1
L. Impacts of Water Conservation on Alternative
Technologies II-L-1
Chapter III - USE OF SOILS DATA
A. Soils Relationships Study III-A-1
B. Pickerel Lake, Michigan, Cluster System Site Analysis III-B-1
Chapter IV - COST ANALYSIS
A. Cost Variability Study IV-A-1
B. Planning and Design Costs for Small Waste Flows Areas IV-B-1
C. Cost Effectiveness Analysis in Small Waste Flows Areas IV-C-1
D. Economic Analyses of Flow Reduction Devices and Programs IV-D-1
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Table of Contents (continued)
Chapter V - THE ROLE OF ENGINEERS
A. Problems of Professional Liability in Relation to
Innovative and Alternative Wastewater Treatment
Technologies for Small Communities in U.S. EPA Region V V-A-1
APPENDIX--The Law of Designer's Liability
Chapter VI - DESIGN OF SMALL WASTE FLOWS MANAGEMENT AGENCIES
A. Functions of Small Waste Flows Management Agencies VI-A-1
B. Local Options in Design VI-B-1
C. Guidance for Analysis of Existing Functional Capabilities:
Manpower and Authority VI-C-1
D. Manpower Projections for Small Waste Flows Agencies VI-D-1
E. Estimating Administration and Operations Costs VI-E-1
F. Existing Training Programs for Small Waste Flows
Management and Operations VI-F-1
G. Training Programs Needed VI-G-1
H. Design Process for Small Waste Flows Agencies VI-H-1
I. Hypothetical Small Waste Flow Management Programs VI-I-1
Chapter VII - VARIANCES
A. Environmental and Economic Justifications for Variances VII-A-1
B. Effects of Variance Procedures on Agency Design,
Manpower and Cost VII-B-1
Chapter VIII - IMPLEMENTATION
A. Rights of Entry to Private Property in Connection with
Publicly Managed Decentralized Wastewater Systems VIII-A-1
B. User Charge Study VIII-B-1
C. Water Quality Monitoring Plans VIII-C-1
D. Implementation Methods for Water Conservation VIII-D-1
Chapter IX - PLANNING AREA DEFINITION
A. Developmental and Environmental Criteria for
Identification of Small Waste Flows Areas IX-A-1
B. Approaches for Defining Planning Area Boundaries IX-B-1
C. Use of Segmentation in SWF Planning and Implementation IX-C-1
Chapter X - DEMOGRAPHY AND RECREATION
A. Number and Range of Rural and Rural Lake Projects X-A-1
B. Population Projection and Impact Techniques X-B-1
C. Recreation Home Demand X-C-1
D. Recreation Planning X-D-1
E. On-Site Systems in Region V and Potential Cost Avoidance
from Adoption of Optimum Operation Alternatives X-E-1
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Table of Contents (concluded)
Chapter XI - LAND USE AND ENVIRONMENTAL CONSTRAINTS
A. The Interrelationship Between Small Waste Flows Facility
Planning and Land Use XI-A-1
B. Environmental Constraints Evaluation Methodology XI-B-1
C. Multiple Use of Cluster System Sites XI-C-1
Chapter XII - SURFACE WATER RESOURCES -
A. Extent of Surface Water Quality Data Available in
U.S. EPA Region V States XII-A-1
B. Availability of Non-Point Source Data XII-B-1
C. Review of Lake Water Quality Modeling Techniques XII-C-1
D. Review of Rural Non-Point Modeling Techniques XII-D-1
E. Guidelines for Surface Water Quality Data Collection
in Step 1 Facilities Planning XII-E-1
F. Evaluation of the Significance of On-Site Systems in
Water Quality Management of Lakes XII-F-1
G. Water Quality Benefits of Non-Point Source Control XII-G-1
Chapter XIII - GROUNDWATER RESOURCES
A. Extent of Groundwater Quality Data Available in
U.S. EPA Region V States XIII-A-1
B. Review of Groundwater Modeling Techniques XIII-B-1
C. Groundwater Resources Data Needed for Facilities
Planning in Rural Lake Areas XIII-C-1
Chapter XIV - PUBLIC PARTICIPATION
A. Public Participation Plans for Rural Planning Areas XIV-A-1
Chapter XV - STATE AND 208 PROGRAMS
A. Review of State Codes and Implementation Authority for
SWF Management XV-A-1
B. Organization and Manpower for On-Site Regulation XV-B-1
C. Potential 208 Program Roles in Small Waste Flows Areas XV-C-1
D. Benefits of Separate State Priority Lists for Small
Waste Flow Areas XV-D-1
Chapter XVI - FEDERAL PROGRAMS
A. EPA Policy Regarding Conventional Water Use and
Population Growth XVI-A-1
B. Federal Water Quality Improvement Programs in Rural Lake
Areas — XVI-B-1
C. Federal Programs Affecting Construction Grants Activities
in Rural Lake Areas XVI-C-1
D. Alternative Construction Grants Procedures for Small
Waste Flow Areas XVI-D-1
APPENDIX A - Region V Guidance
E. The Davis-Bacon Act and Small Community Alternative
Wastewater Management Projects Funded by EPA XVI-E-1
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LIST OF TABLES
TABLE PAGE
II-A-1 Representative Bacteriological Quality of II-A-4
Septic Tank Effluent
II-C-1 Direct and Remote Sensing Techniques II-C-9
II-D-1 Spectral Characteristics of Fluorometer Light II-D-3
Filters in ENDECO Model 2100 Septic Leachate
Detector
II-D-2 Absorption and Fluorescence Characteristics II-D-7
of Whitener Samples
II-D-3 Absorption and Fluorescence Characteristics II-D-8
of Detergent Samples
II-D-4 SLD Fluorometer Responses to Selected Cleaning II-D-11
Products
II-D-5 Absorption and Fluorescence Characteristics II-D-14
of Selected Organic Materials
II-D-6 Chemical and SLD Analysis of Septic Tank Samples II-D-21
II-D-7 Linear Regression Analysis of Chemical and SLD II-D-22
Data for Septic Tank Samples
II-D-8 Sand Column #1 - Permeate Data II-D-32
II-D-9 Sand Column #2 - Permeate Data II-D-33
II-D-10 Sand and Clay Column #3 - Permeate Data II-D-37
II-D-11 SLD Readings for Inflowing Streams II-D-51
II-H-1 Typical Values of Permeability Coefficients II-H-4
II-K-1 Testing Methods for Determining Hydraulic II-K-7
Conductivity of Soils Generally Applicable at
or Above the Water Table
II-K-2 Testing Methods for Determining Hydraulic II-K-9
Conductivity of Soils Generally Applicable
Below the Water Table
II-L-1 Typical Flow Rates and Temperatures II-L-2
III-A-1 Approximate Percentage of Counties by State in III-A-2
Region V with Completed Soil Surveys as of 1978
III-A-2 Soil Limitations Ratings Used by SLS for Septic III-A-5
Tank/Soil Absorption Fields
III-A-3 Alternatives to Standard Septic Tank - Soil III-A-6
Absorption Systems
III-A-4 Correlation of On-site System Problems with III-A-22
Soil Series Characteristics, in the First
Decision-making Process, Salem Case
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LIST OF TABLES (CONTINUED)
TABLE PAGE
III-B-1 Groundwater Sampling Results at Pickerel Lake, MI III-B-12
III-B-2 Soil Testing Results at Pickerel Lake, MI III-B-13
IV-A-1 Facilities for which Cost Ranges were Developed IV-A-3
in Cost Variable Study
IV-A-2 Effect of Topography on Sewerage System Design IV-A-8
IV-A-3 Physical/Environmental Constraint Scenarios for IV-A-10
Rural Areas
IV-A-4 On-site System Technologies for Various Scenarios IV-A-11
IV-A-5 Present Worth and Dwelling Unit Statistics for IV-A-17
Facilities
IV-A-6 Cost Variability Study Results IV-A-19
IV-A-7 Graphic Data Prepared in Cost Variability Study IV-A-20
IV-A-8 Population, Housing and Flow Assumptions by IV-A-27
Housing Densities
IV-A-9 Design Assumptions IV-A-31
IV-A-4-1 Index of Technology, Scenario and Cost Effective IV-A-43
Option Graphs Prepared During Cost Variability
Study
IV-A-4-2 Through IV-A-4-16 Cost Variability Study Results
(See Section IV-A, Appendix B)
IV-B-1 Costs for Engineering, Contingencies, Legal, IV-B-1
Administrative, and Site Specific Analysis for
Centralized vs. Decentralized Treatment Systems
IV-C-1 Costs to be Included in Cost Analyses for IV-C-2
Centralized and Decentralized Facilities
IV-C-2 Costs to be Included in Cost Analyses for IV-C-3
Decentralized Facilities
IV-C-3 Costs to be Included in Cost Analyses for IV-C-4
Decentralized Facilities
IV-D-1 Description and Use of Methods for Economic IV-D-1
Comparison
IV-D-2 Costs of a Flow Conservation Program IV-D-1
IV-D-3 Benefits of a Flow Conservation Program IV-D-2
IV-D-4 Net Monetary Benefits for a Community IV-D-10
IV-D-5 Non-monetary Benefits and Costs IV-D-11
VI-C-1 Estimates of Level of Effort Required for VI-C-8
Function Performance
VI-C-2 Authority Required for Performance of VI-C-12
Functions
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LIST OF TABLES (CONTINUED)
TABLE PAGE
VI-E-1 Actual Annual User Charge for Communities VI-E-2
Employing Small Waste Flows Technology
VI-E-2 Estimated Annual O&M and Administrative Costs VI-E-5
for Six Rural Lake Areas
VI-I-1 Population Distribution and Sewer Service in VI-I-2
Milton
VI-I-2 Management Models VI-I-8
VII-B-1 Existing Conditions and Proposed Corrective VII-B-2
Actions Under Standard and Non-standard
Compliance Options
VII-B-2 Present Worth Costs for Standard vs. Non-standard VII-B-4
Compliance for Scenario 1
VII-B-3 Present Worth Costs for Standard vs. Non-standard VII-B-5
Compliance for Scenario 2
IV-A-9 Design Assumptions IV-A-31
IV-A-4-1 Index of Technology, Scenario and Cost Effective IV-A-43
Option Graphs Prepared During Cost Variability
Study
IV-A-4-2 Through IV-A-4-16 Cost Variability Study Results
(See Section IV-A, Appendix B)
IV-B-1 Costs for Engineering, Contingencies, Legal, IV-B-1
Administrative, and Site Specific Analysis for
Centralized vs. Decentralized Treatment Systems
IV-C-1 Costs to be Included in Cost Analyses for IV-C-2
Centralized and Decentralized Facilities
IV-C-2 Costs to be Included in Cost Analyses for IV-C-3
Decentralized Facilities
IV-C-3 Costs to be Included in Cost Analyses for IV-C-4
Decentralized Facilities
IV-D-1 Description and Use of Methods for Economic IV-D-1
Comparison
IV-D-2 Costs of a Flow Conservation Program IV-D-1
VII-B-4 Present Worth Costs for Standard vs. Non-standard VII-B-6
Compliance for Scenario 3
VII-B-5 Present Worth Costs for Standard vs. Non-standard VII-B-7
Compliance for Scenario 4
VIII-B-1 Examples of User Charge Allocation Options VIII-B-7
VIII-B-2 Back-up Costs for Hypothetical User Charge VIII-B-8
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LIST OF TABLES (CONTINUED)
TABLE PAGE
IX-A-1 Factors Varied and Technologies Considered in IX-A-6
the Cost Variability Study
IX-A-2 Trade-off Densities (in Homes Per Mile) Above IX-A-7
which Off-site Facilities are Competitive
IX-A-3 Number of Houses in a Community Below which IX-A-13
Total Local Funding would be Less Expensive
for the Community than Federal Funding
IX-A-4 Net and Percentage Savings to Unsewered Com- IX-A-14
munities with 100 Homes
IX-A-5 Net and Percentage Savings to Unsewered Com- IX-A-15
munities with 1000 Homes
X-A-1 Estimated Total and Proportional Sample by State X-A-2
and Population Category of Rural Projects in
U.S. EPA Region V
X-A-2 Projection of Small Communities of Population X-A-3
2,500 - 10,000 in Region V Potentially Applying
for Construction Grants Assistance after 1985
X-A-3 Projection of Small Communities of Population X-A-4
0 - 2,500 in Region V Potentially Applying for
Construction Grants Assistance after 1985
X-A-4 Characteristics of Selected Rural Projects in X-A-9
Illinois
X-A-5 Characteristics of Selected Rural Projects in X-A-12
Indiana
X-A-6 Characteristics of Selected Rural Projects in X-A-15
Michigan
X-A-7 Characteristics of Selected Rural Projects in X-A-19
Minnesota
X-A-8 Characteristics of Selected Rural Projects in X-A-22
Ohio
X-A-9 Characteristics of Selected Rural Projects in X-A-26
Wisconsin
X-C-1 Seven Rural Lake EIS's Population Projections X-C-1
X-C-2 Dwelling Units Per Acre Permitted Under Lakeshore X-C-2
Zoning Ordinances
X-C-3 Recreation Demand in the North Central Region of X-C-3
the United States
X-E-1 1977 Urban, Rural Non-farm, and Rural Farm Popu- X-E-1
lations of Region V States
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LIST OF TABLES (CONTINUED)
PAGE
1977 Numbers of Households and Number of House- X-E-2
holds Served by On-site Systems in Region V
X-E-3 Percentages and Numbers of Residences Per X-E-3
Density Class
X-E-4 Partition of 1977 Urban and Rural Non-farm X-E-5
On-site Systems by Density Class
X-E-5 Technology Mixes, Present Worth Costs Per X-E-6
House and Total Costs for Optimum Operation
of 430 Thousand Residences
X-E-6 Present Worth Costs Per House and Total Costs X-E-7
for Sewering 430 Thousand Residences
XI-A-1 Sanitary Code Separation Distance Requirements XI-A-1
for Soil Absorption Systems
XII-A-1 Summary of Lake Data that are Available from the XII-A-6
Primary State Agencies in Region V
XII-C-1 Relationships Developed by Reckhow XII-C-20
XII-C-2 A Comparison of Simplistic Phosphorus Loading XII-C-23
Models for Lakes
XII-C-3 Physical Characteristics of Nest Lake and Green XII-C-23
Lake
XII-C-4 Hydraulic Budget for Nest Lake and Green Lake XII-C-25
XII-C-5 Phosphorus Budgets for Nest Lake and Green Lake XII-C-26
XII-D-1 Per Capita Contribution of Phosphorus (Ec) in XII-D-4
Domestic Sewage
XII-D-2 Ranges and Mean Values for Export of Total XII-D-5
Phosphorus
XII-D-3 Indications of the General Magnitude of the XII-D-12
Soil-erodibility Factor
XII-D-4 Values of the Erosion Equation's Topographic XII-D-13
Factor
XII-D-5 Generalized Values of the Cover and Management XII-D-14
Factor
XII-D-6 Values of Support-Practice Factor XII-D-16
XII-D-7 Rural Non-point Source Pollutant Matrix XII-D-18
XII-D-8 Summary of Experimentally Determined Enrich- XII-D-19
ment Ratios
XII-D-9 Applicability of Deterministic Non-point Source XII-D-22
Models to Various Problem Contexts
XII-G-1 Principle Types of Cropland Erosion Control XII-G-2
Practices and their Highlights
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TABLE OF CONTENTS (CONTINUED)
TABLE PAGE
XII-G-3 Practices for the Control of Nutrient Loss from XII-G-8
Fertilizer Applications and Animal Wastes
XII-G-4 Costs and Returns for Selected Options XII-G-10
XII-G-5 Simulation for Alternative Strategies XII-G-12
XIII-A-1 Region V State Agencies that are Responsible XIII-A-9
for the Collection and Maintenance of Ground-
water Data
XIII-A-2 Summary of State Health Department Activities XIII-A-11
that are Related to Private Home Water Supplies
in Region V States
XIII-A-3 List of USEPA and USGS offices that can Provide XIII-A-14
Computerized Data
XIII-B-1 Data Requirements to be Considered for a XIII-B-8
Predictive Model
XIV-A-1 Distinctions Between Basic and Full-scale XIV-A-3
Participation Programs
XIV-A-2 Model Plan of Study Outline XIV-A-5
: Basic Program (Town of 10,000)
XIV-A-3 Public Participation Work Plan for Basic Program XIV-A-7
XIV-A-4 Model Plan of Study: Full Scale Participation XIV-A-10
XV-D-1 Evaluation of Priority Ranking Criteria used for XV-D-3
EPA's Construction Grants Program in Illinois
XV-D-2 Evaluation of Priority Ranking Criteria used for XV-D-4
EPA's Construction Grants Program in Indiana
XV-D-3 Evaluation of Priority Ranking Criteria used for XV-D-5
EPA's Construction Grants Program in Michigan
XV-D-4 Evaluation of Priority Ranking Criteria used for XV-D-6
EPA's Construction Grants Program in Minnesota
XV-D-5 Evaluation of Priority Ranking Criteria used for XV-D-7
EPA's Construction Grants Program in Ohio
XV-D-6 Evaluation of Priority Ranking Criteria used for XV-D-8
EPA's Construction Grants Program in Wisconsin
XVI-D-1 Data Collection and Alternatives XVI-D-12
Development for Unsewered Areas
Sequence 1 - Region V Guidance
XVI-D-2 Data Collection and Alternatives XV-D-13
Development for Unsewered Areas
Sequence 2 - Volunteer Participation by Owners
XVI-D-3 Data Collection and Alternatives XVI-D-15
Development for Unsewered Areas
Sequence 3 - Early Review of Available Data/
Complex Solutions
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LIST OF TABLES (CONCLUDED)
TABLE PAGE
XVI-D-4 Data Collection and Alternatives XVI-D-16
Development for Unsewered Areas
Sequence 4 - Early Review of Available Data/
Standard On-site Upgrading and Development
XVI-D-5 Data Collection and Alternatives XVI-D-17
Development for Unsewered Areas
Sequence 5 - Available Data and Community
Surveys Sufficient for Step 1
XVI-D-6 Data Collection and Alternatives XVI-D-18
Development for Unsewered Areas
Sequence 6 - No Need for Centralized
Facilities/Expounded Step 1
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LIST OF FIGURES
FIGURE PAGE
II-B-1 Collector Sewer Eligibility II-B-2
II-D-2 Chemical Structures of Five Classes of
Fluorescent Whitening Agents II-D-5
II-D—3 Absorbence and Fluorescence of Dodeculbenzene
Sulfonate II-D-9
II-D-4 Absorbence and Fluorescence of Crooked Lake
Hypolimnion Waste With and Without Detergent II-D-13
II-D-5 Absorbence and Fluorescence of Tannic Acid With
and Without Added Detergent II-D-15
II-D-6 Thin-Layer Chromatography of Laboratory-Grade
Organic Chemicals on Polar Solid Phase
II-D-7 Thin-Layer Chromatography of Laboratory-Grade
Organic Chemicals on Non-Polar Solid Phase II-D-18
II-D-8 Thin-Layer Chromatography of Septic Tank
Samples on Polar Solid Phase II-D-24
II-D-9 Thin-Layer Chromatography of Septic Tank
Samples on Non-Polar Solids II-D-25
II-D-10 Thin-Layer Chromatography of Septic Tank
Samples on Non-Polar Solid Phase II-D-26
II-D-11 Thin-Layer Chromatography of Septic Tank
Samples on Non-Polar Solid Phase II-D-27
II-D-12 Absorbence and Fluorescence of a Typical Septic
Tank Sample II-D-29
II-D-13 Long Wavelength Response in Non-Filtered and
Filtered Septic Tank Samples II-D-30
II-D-14 Shift in Long Wavelength Response at Varying
Excitation Wavelengths II-D-31
II-D-15 Effluent Plumes and Groundwater Flow Recorded
During Previous Studies II-D-35
II-D-16 Shoreline Segments Scanned Several Times
During 1980 Field Investigations II-D-36
II-D-17 Suspected Effluent Plumes Detected Within
Designated Segments, 26 August-14 September 1980 II-D-39
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LIST OF FIGURES (.CONTINUED)
FIGURE PAGE
II-D-18 Examples of SLD Responses: Smallest Plume,
Largest Plume, and Constant Background II-D-40
II-D-19 Comparison of Organic Channel and Combined
Signal Recordings, 30 August 1980 II-D-42
II-D-20 Locations of Bottom Scan Transects II-D-45
II-D-21 SLD Organic Channel Recordings on Plume
Emergence Point Transects II-D-46
II-D-22 Fluorescence Response of SLD to Crooked Lake
Hypolinmion II-D-47
II-D-23 Shoreline Scan on South Shore of Crooked Lake
Where Stream From Loon Lake Enters II-D-49
II-D-24 Sampling Points on Streams Entering Crooked Lake II-D-50
II-D-25 Stream Plume and Eddy Currents, Lake George,
New York, August 1981 II-D-52
II-D-26 Comparison of Combined Signal and Organic
Channel Recordings II-D-54
II-H-1 Diagrammatic Representation of Basic Site
Geohydrologic Investigation for a Water Table II-H-3
II-J-2 Decision Flow Diagram for Existing On-Site Systems II-J-2
II-L-1 Wastewater Temperature vs. Ambient Water
Temperature II-L-3
III-A-1 Detailed Soils Map III-A-4
III-A-2 Typical Soil Boundaries and Variations in Soil
Boundaries III-A-8
III-A-3 Location of Surface Malfunctions As Correlated
With Soil Survey Data in Salem Utility
District No. 2 III-A-19
III-A-4 Detailed Correlation of Available Soil and
Malfunction Data for Salem Utility District No. 2
III-B-1 The Two Properties Proposed for Cluster
Drainfields On Which Soil Boring Programs Were
Conducted III-B-2
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LIST OF FIGURES (CONTINUED)
FIGURE PAGE
III-B-2 Soil Boring Locations on the Charles Kreeger
Property III-B-6
III-B-3 Soil Boring 1, Charles Kreeger Property III-B-7
III-B-4 Soil Boring 2, Charles Kreeger Property III-B-
III-B-5 Soil Boring 3, Charles Kreeger Property III-B-10
III-B-6 Generalized Geologic Cross-Section of the
Charles Kreeger Property III-B-11
III-B-7 Soil Boring Locations on the Warren Keller
Property III-B-16
III-B-8 Soil Boring 4, Warren Keller Property III-B-17
III-B-9 Soil Boring 5, Warren Keller Property III-B-18
III-B-10 Soil Boring 6, Warren Keller Property III-B-19
III-B-11 Soil Boring 7, Warren Keller Property III-B-20
III-B-12 Generalized Geologic Cross-Section of the
Warren Keller Property III-B-21
IV-A-1 Present Worth Dollars Per Dwelling Unit of
Non-Collection Facilities IV-A-16
IV-A-2 Technology Curve Example
0% Growth IV-A-22
IV-A^3 Techology Curve Example
50% Growth IV-A-23
IV-A-4 Scenario Curve Example
0% Growth IV-A-24
IV-A-5 Scenario Curve Example
50% Growth IV-A-25
IV-A-4-1 through IV-A-4-132: See Table IV-A-4-1.
IV-D-1 Change in Staging Period of Treatment Facilities
As a Result of Flow Conservation IV-D-3
IV-D-2 Change in Size of Treatment Facilities As a
Result of Flow Conservation IV-D-3
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LIST OF FIGURES (.CONTINUED)
FIGURE PAGE
IV-D-3 Change in Staging and Size of Treatment Facilities
As a Result of Flow Reduction IV-D-4
VI-A-1 Potential Management Agency Functions VI-A-2
VI-A-1A through VI-A-5A, Management Functions: See Sec. VI-A, App. A.
VI-D-1 Manpower Estimates for the Seven Rural Lake EIS's,
Based On the Optimum Operation Alternative VI-D-3
VI-D-2 Projected Manpower Needs for Region V With Full
Utilization of Optimum Operation Alternative VI-D-4
VI-H-1 Potential Management Agency Functions VI-H-4
VI-H-2 Local Decisions in Management Agency Design VI-H-5
VI-H-3 Major Factors Influencing Agency Design Decisions VI-H-6
VI-H-4 Management Agency Design Decision Flow Diagram VI-H-7
VI-I-1 Miford County VI-I-3
X-A-1 Involvement of Small Communities in the
Construction Grants Program X-A-6
X-A-2 Distribution of Rural Projects in Illinois X-A-8
X-A-3 Distribution of Rural Projects in Indiana X-A-11
X-A-4 Distribution of Rural Projects in Michigan X-A-14
X-A<-5 Distribution of Rural Projects in Minnesota X-A-18
X-A-6 Distribution of Rural Projects in Ohio X-A-21
X-A-7 Distribution of Rural Projects in Wisconsin X-A-25
X-B-1 Geographic Areas Typically Associated With
Wastewater Management Planning for Rural Areas X-B-2
XI-B-1 Environmental Constraints Evaluation XI-B-2
XII-C-^1 Vollenweider's Total Phosphorus Loading and
Mean Depth Relationship XII-C-4
XII-C-2 Phosphorus Loading vs. Mean Depth/Hydraulic
Residence Time XII-C-6
-------
LIST OF FIGURES (.CQNTINUEDl
FIGURE PAGE
XII-C-3 Phosphorus Loading vs. Mean Depth/Hydraulic
Residence Time XII-C-8
XII-C-4 Critical Phosphorus Loading vs. Mean Depth XII-C-9
XII-C-5 Vollenweider Critical Phosphorus Loading and
Hydraulic Loading Relationship XII-C-10
XII-C-6 Dillon Phosphorus Loading - Phosphorus Retention
and Mean Depth Relationship XII-C-12
XII-C-7 Larsen and Mercier Influent Phosphorus and
Phosphorus Retention Relationship XII-C-14
XII-C-8 Chlorophyll a. and Phosphorus Loading Relationship XII-C-16
XII-C-9- Secchi Depth and Phosphorus Loading Relationship XII-C-17
XII-C-10 Hypolimnetic Oxygen Depletion Rate and Phosphorus
Loading Relationship XII-C-18
XII-C-11 Measured Values of Total Phosphorus and
Calculated Values XII-C-19
XII-C-12 Nest Lake/Green Lake, Minnesota XII-C-24
XII-C-13 Trophic Conditions of Nest Lake and Green Lake XII-C-27
XII-D-1 Geologic Classification and Stream Phosphorus
Concentrations XII-D-7
XII-D-2 Geologic Classification and Stream Nitrogen
Concentrations XII-D-8
XII-D-3 Average Annual Values of the Rainfall-Erosivity
Factor XII-D-10
XII-D-11 Nomograph for Determining Soil-Erodibility Factor XII-D-11
XI1-E-1 Sequential Use of Water Quality Models, Field
Data, and Alternatives for Facilities Planning
in Rural Lake Communities XII-E-2
XII-F-1 Factors Affecting Lake Quality XII-F-2
XII-F-2 Nest Lake/Green Lake, Minnesota XII-F-8
XII-F-3 Dillon Phosphorus Loading - Phosphorus Retention
and Mean Depth Relationship XII-F-10
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LIST OF FIGURES (.CONTINUED)
FIGURE PAGE
XII-F-4 Lake Phosphorus Concentration Due to On-Site
Systems XII-F-12
XII-F-5 Relationship Between Areal and Phosphorus
Retention XII-F-14
XII-G-1 Flow Chart for Assessing Erosion Problems and
Selecting Physically Feasible Control Practices
for Large Areas XII-G-5
XII-G-2 Flow Chart for Assessing Erosion Problems and
Selecting Physically Feasible Control Practices
for Field-Sized Areas XII-G-6
-------
DISCLAIMER
These Technical Reference Documents have been reviewed by the Water
Division, U.S. Environmental Protection Agency, Region V, and approved for
publication. Approval does not signify that the contents necessarily reflect
the views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
-------
FOREWORD
The Construction Grants Program, authorized in Title II of the Federal
Water Pollution Control Act of 1972, provides federal grants to municipalities
and other eligible recipients for the purpose of planning, designing, and
constructing wastewater facilities. The objectives of the Act and of the
Construction Grants program "is to restore and maintain the chemical,
physical, and biological integrity of the Nation's waters."
Region V administers the Construction Grants program for the states of
Ohio, Indiana, Illinois, Michigan, Wisconsin, and Minnesota.
In the mid-1970's we became aware of a class of grant applications that
had the following characteristics:
• the communities to be served by the proposed facilities were developed
around lakes in rural areas,
• the communities had a high proportion of seasonal residents,
• the proposed facilities were centralized sewers and treatment plants,
and
• the costs per household were among the highest seen by the Region.
As a class, these applications presented one of the most complex sets of
environmental, social, and technical issues that the Region has faced.
In 1977 we selected seven representative projects to study in detail
through the preparation of environmental impact statements. These seven case
studies provided the factual basis for subsequent preparation of Region V's
Generic Environmental Impact Statement for Wastewater Management in Rural Lake
Areas, the final version of which was published in January 1983.
The Technical Reference Documents that make up the document you are
reading now constitute an intermediate step between the seven case studies and
the Generic EIS. The many issues, methods, and alternatives that were
recognized during preparation of the case studies are addressed in depth in
these Technical Reference Documents. The Region reviewed these reports during
preparation of the Generic EIS. These documents contain much valuable infor-
mation that could not be included in the Generic EIS because of space limita-
tions. However, they should be viewed as working papers, not final EPA posi-
tions. Some of the information has been outdated by the Municipal Construc-
tion Grants Act of 1981 and by new regulations implementing the Act. The
Region is publishing the complete set of Technical Reference Documents to make
all of our work available to the public and to provide additional background
on the issues and recommendations presented in the Generic EIS.
-------
PREPARERS
These Technical Reference Documents were prepared by the staff of WAPORA,
Inc., Chevy Chase, Maryland. Mr. Gerald Peters, Jr. was WAPORA1s Project
Manager and Principal Investigator. Mr. Eric Hediger was WAPORA's Assistant
Project Manager. Four of the Technical Reference Documents were prepared by
the Clean Water Fund, under the direction of Mr. Larry Silverman.
The U.S. Environmental Protection Agency's Project Officers were Mr.
Theodore Rockwell and Mr. Jack Kratzmeyer, of Region V's Environmental Impact
Section. Mr. Alfred Krause, Region V's Small Waste Flows Specialist, also
provided invaluable guidance.
WAPORA's and the Clean Water Fund's project staff, their areas of
expertise, and Technical Reference Documents for which they were principally
responsible are listed below:
Name
Gerald 0. Peters, Jr.
Project Manager
Eric M. Hediger
Assistant Project Manager
Edward D. Hagarty
Environmental Engineer
Wu-Seng Lung
Water Resources Engineer
Stuart D. Wilson
Environmental Health
Scientist
Richard M. Loughery
Public Administration
Specialist
Estelle K. Schumann
Environmental Health
Scientist
Highest Degree
M.S., Environmental Science
and Engineering
Registered Sanitarian
Technical
Reference
Documents
II-B,D,E,F,
G, I; VIII-C;
IX-A,B; X-A,
E; XV-D;
XVI-A.D
M.E.M., Environmental Management III-A; IV-A
M.S., Civil Engineering
Professional Engineer
Ph.D., Environmental Engineering
Professional Engineer
M.S., Environmental Health
M.P.A., Environmental Policy
M.S., Environmental Science
I; II-J,L;
IV-A,B,C,D;
VIII-D
XII-C,D,E,F,G
VI-A,B,C,D,E,
F,G,H,I;
VII-A,B; XV-C
VIII-B; XV-A,
B
II-A; XII-A;
XIII-A
J. Ross Pilling
Environmental Planner
M.R.P., Regional Planning
IX-C; X-C,D;
XI-A,B,C;
XIV-A; XVI-B,
C
-------
Name
Roger Moose
Hydrogeologist
Gerald D. Lenssen
Agricultural Engineer
Jerald D. Hitzemann
Demographer
Mirza H. Meghji
Sanitary Engineer
Rhoda Granat
Librarian/Editor
Melissa Wieland
Graphic Artist
Stephanie Davis
Editor
Catherine Skintik
Editor
Highest Degree
M.S., Geology
Technical
Reference
Documents
II-C.H;
XIII-B,C
M.S., Agricultural Engineering II-K, III-B
M.C.P., City Planning
Ph.D., Environmental Engineering
Professional Engineer
M.A., Psychology
B.A., Biology
B.A., English
M.A., English
X-B
IV-A; XII-B
CLEAN WATER FUND
Susan B. Grandis
Legal Researcher
Edward Hopkins
B.A., Legal Studies
M.A., History and Political
Science
V-A; VII-A;
XVI-E
-------
PART ONE
TECHNOLOGY ALTERNATIVES
-------
CHAPTER 1
FACT SHEETS
-------
FLOW REDUCTION - TOILET TANK DAMS FACT SHEET 1.1
October 1980
DESCRIPTION
Toilet tank dams are devices designed primarily to save water in existing toilets by reducing
the amount of water per flush. They are inserted in the tank on each side of the drain to retain
excess water not required for flushing. The dams, which are made of plastic, fiberglass, or
rubber-coated metal, are flexed and vertically inserted in the toilet tank to form the "dams" that
retain water. In California's pilot water conservation program (12), dams were the most successful
of all toilet tank devices used for saving water. Public acceptance was quite favorable.
COMMON MODIFICATIONS
Dam devices can be modified to provide a "dual flush" for existing toilets. By removing a
small semi-circular section at the base of the unit and then quickly depressing and releasing the
handle, a reduced flushing action occurs. By holding down the handle, the water in the tank drains
and a full flushing action occurs.
TECHNOLOGY STATUS
Toilet tank dams are fully developed and simply constructed (28). Various municipal codes
would need to be changed if the dams reduced the flush volume below that required (53).
APPLICATIONS
This type of flow reduction device can be used to save fresh water, thereby lowering one's
water and sewer bill and extending the life of an on-site disposal system or prolonging fresh water
availability, especially in times of drought. Annual savings are reported to range from 4.4% to
7.5% of a family's total water consumption (indoor and outdoor) (53).
LIMITATIONS
California's pilot water conservation program (12) indicates that one of the problems with the
dams is the need for double flushing to ensure proper operation. However, proper adjustment of the
dams alleviates this problem. In some cases, inefficient or low-volume toilets do not allow for
use of dams.
TYPICAL EQUIPMENT/NO. OF MFRS.
There are many types of devices and at least 15 manufacturers (12).
PERFORMANCE
Toilet tanks often supply more water than is needed for efficient operation of the toilet bowl
and trap. Dams take advantage of this fact by reducing the water used while allowing enough flush
water to adequately remove solids (28). In a test of 13 devices, the average reduction of flushing
water was 30% (12).
PLIABILITY
Of the 13 devices tested in the California pilot study, 12 offered a warranty ranging from one
year to the lifetime of the fixture (12). Owing to the corrosion-free materials used for these
devices, the units themselves should not create problems of reliability. Adjustment problems, as
mentioned under "limitations," might be the only problem to affect reliability.
ENVIRONMENTAL IMPACT
Toilet tank dams have a beneficial impact. For a small cost, about 30% of the water normally
used for flushing can be saved; this reduction affects the size of transmission systems or post-
pones the need for expansion.
REFERENCES
12, 16, 53, 28.
I-A-1
-------
FLOW REDUCTION - TOILET TANK DAMS
October 1980
FACT SHEET 1.1
DIAGRAM
TOILET TANK DAMS
BALLCOCK TOILET TANK DAMS
f£
JL FLUSH FLOAT
LEVER VALVE 8ALL
(53)
TOILET TANK DAMS
NORMAL
LEVEL "
^WATER SAVED WITH-
DAMS (53)
ENERGY NOTES
No hot water is saved. However, water demand and wastewater generation changes affect energy
requirements for treatment, supply, and disposal (12).
COSTS
1980 dollars; ENR = 3260. Toilet tank dams cost from $5 to $9 for a set to fit one toilet.
No maintenance is required, no tools are required for installation, and installation takes less
than 5 minutes (12).
I-A-2
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FLOW REDUCTION - SHALLOW TRAP TOILETS FACT SHEET 1.2
October 1980
DESCRIPTION
Shallow trap (low flush) toilets, similar to conventional toilets but with a smaller tank, are
designed to flush with less water because of the shallow trap. With a smaller elevation to over-
come, the siphoning action begins with less water clearing the bowl (in the same manner as a con-
ventional toilet). In many localities, low flush toilets are required by plumbing codes for new
installations (53, 61).
TECHNOLOGY STATUS
Shallow trap toilets are fully developed and commercially available from all major toilet
fixture manufacturers (53).
APPLICATIONS
Shallow trap toilets function and have similar applications as do conventional toilets. They
may be used in association with collection and centralized treatment or with on-site systems.
Because of their public acceptance, they are widely used except where water supply limitations or
on-site sewage disposal limitations dictate greater reductions in water use.
LIMITATIONS
With the lower flows from shallow trap toilets, the possibilities of solids settling out of
the waste stream appear greater; however, studies have proven this to be wrong. Hydraulic calcula-
tions need to be made if the toilets are to discharge to an infrequently used sewer with flat
grades (17).
Difficulty in using additional water saving devices (such as dual flush or dam devices with
shallow trap toilets) has been reported (16).
TYPICAL EQUIPMENT/NO. OF MFRS.
Shallow trap toilet/9 (53, 61).
PERFORMANCE
Flow per use = 3.5 gal. (53, 13, 61). Performance of shallow trap toilets has been acceptable
as seen from the plumbing codes that now require their use (e.g. Suburban Washington and
California). In a test program, shallow trap toilets were installed in 6 houses; 83% of the
respondents found the performance of the toilet acceptable and would recommend it to others (16).
RELIABILITY
In the areas of California and suburban Washington where code requirements call for shallow
trap toilets, no major problems have been reported (73). The plumbing code requirements have been
in effect since 1973 in the Washington area and since January, 1978 in California, which indicates
the length of time that this type of toilet has given reliable service on a large scale.
ENVIRONMENTAL IMPACT
A positive environmental impact results from the use of shallow trap toilets due to the con-
servation of water and energy resources without a capital expenditure greater than conventional
toilets.
REFERENCES
53, 61, 17, 43, 16, 28, 13, 73, 78, 74.
I-A-3
-------
FLOW REDUCTION - SHALLOW TRAP TOILETS FACT SHEET 1.2
October 1980
DIAGRAM
SMALLER TANK
(53)
SHALLOW TRAP TOILET
ENERGY NOTES
No hot water is used for toilet flushing and subsequently no energy savings are realized by
the homeowner in this area. Rural areas that pump water from wells realize an energy savings from
reduced pumping costs due to the reduction in water from the shallow trap toilet.
COSTS
1980 dollars; ENR Index = 3260. Capital costs for low flush toilets are comparable to costs
for conventional toilets.
OPERATION AND MAINTENANCE
Shallow trap toilets are similar to conventional toilets in construction and installation. In
addition, their maintenance requirements do not vary greatly, even though the trapway is smaller,
which means greater possibility of clogging (53).
When retrofitting with some models, the separation between the back of the toilet tank and the
wall is six to nine inches, which may be aesthetically or physically unacceptable in some
applications (78).
I-A-4
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FLOW REDUCTION - AIR ASSISTED TOILETS FACT SHEET 1.3
October 1980
DESCRIPTION
This type of low flush toilet uses compresssed air and a small volume of water (2 quarts) to
discharge waste from the toilet. The flushing action begins by pushing the flush handle that turns
on the water and opens a flapper valve in the bottom of the bowl. When the washing action is
complete, the flapper valve closes, the bowl fills up and the waste is in the chamber below the
bowl. At this time a burst of air ejects the waste into the usual wastewater line (50, 52). The
required compressed air is supplied by an air compressor. The forceful flushing action aids the
transport of the waste where limited heads exist.
COMMON MODIFICATIONS
Air assisted toilets can be down discharging or rear discharging with rounded or elongated
front. The toilets may also be fitted with a vandal-proof lid.
TECHNOLOGY STATUS
The air assisted toilet is fully developed and commercially available (53).
APPLICATIONS
The air assisted toilet, similar in appearance to conventional toilets, is satisfactory for
homes with conventional sewers or alternative wastewater systems. Additional applications include
recreation facilities, schools, and airports (50). Used in conjunction with holding tanks, these
toilets achieve significant reductions in bacteria and nutrient content of wastewaters disposed
on-site at costs competitive with other no- or low-discharge toilets and with minimal change in
user acceptance.
LIMITATIONS
A number of engineers, architects, sanitarians, and supervisory personnel reported no compli-
cations in septic tanks or in the pipes preceding the septic tanks due to low flush toilets (52).
When two toilets on different floors are retrofitted with an air assisted toilet, the major
difficulty likely to be encountered is supplying the required compressed air to each toilet (78).
TYPICAL EQUIPMENT/NO. OF MFRS.
Air assisted toilets and compressors/1.
PERFORMANCE
By using only two quarts of water per flush, the air assisted toilet reduces water consumption
by 90% over conventional toilets (53, 50). Household water reduction is about 40%. The toilets
have been approved by the Uniform Plumbing Code (UPC), the International Association of Plumbing
and Mechanical Officials (IAPMO), Basic Plumbing Code of the Building Officials and Code
Administrators International (BOCA), and Standard Plumbing Code of the Southern Building Code
Congress International (SBCCI) (50). The performance to date has been good.
RELIABILITY
In a demonstration project resident reactions indicate that air assisted toilets perform as
well as conventional toilets (78). They have been successful at highway rest stops, ski areas,
Army Corps of Engineers lakes, and other installations (53, 52).
ENVIRONMENTAL IMPACT
As with other water conservation devices, the air assisted toilet is beneficial due to the
water savings.
REFERENCES
50, 53, 78, 52, 3.
I-A-5
-------
FLOW REDUCTION - AIR ASSISTED TOILETS
October 1980
FACT SHEET 1.3
DIAGRAM
FLUSH BUTTON
a
WATER SUPPLY
(53)
AIR ASSISTED TOILET
ENERGY NOTES
Air assisted toilets require a compressor that uses about 0.0016 kwh/toilet use. The yearly
power consumption per residence would therefore be 5-15 kwh, which is minimal (78). Energy savings
result from reduced water supply and wastewater treatment requirements.
COSTS
1980 Dollars; ENR Index = 3260. Capital costs for air assisted toilet systems range from $800
to $1,000. This cost includes the toilet and the air compressor. Installation costs are expected
to be about $120 or 4 hours of a plumber's time (3).
OPERATION AND MAINTENANCE
During a recent demonstration project, only minor maintenance by the homeowner was necessary
after the initial "bugs" were worked out. After six months of operation, the oil and air filters
of the air compressor were both fine. No other maintenance was required on the system (78), which
normally requires no additional maintenance than does a conventional toilet system, and possibly
less. Electrical costs would be less than $l/year.
I-A-6
-------
FLOW REDUCTION - LOW FLOW SHOWERS FACT SHEET 1.4
October 1980
DESCRIPTION
Three of the major types of low flow showers are 1) low flow shower heads, 2) restrictors, and
3) air assisted showers. Low flow shower heads resemble conventional shower heads but they reduce
the use of water by various restriction devices such as fixed or variable orifices. Variable
orifices are convex and made of rubber so that as the pressure increases, the size of the orifice
decreases. Restrictors, external and internal, can be installed with existing showers. The inter-
nal restrictor fits within the shower head while the external device is a separate section of pipe
that attaches between the water supply pipe and the shower head. Low flow shower heads and
restrictors reduce water consumption for conventional showers from 3.0 - 10.0 gpm to 1.5 - 3.0 gpm.
In contrast, air assisted showers, which use only 0.5 gpm, operate by mixing air with water at
the shower head to give a full-stream effect. Air assisted showers can be installed in existing
shower stalls or with new construction.
COMMON MODIFICATIONS
Additional water can be saved by cutting off showers while soaping or shampooing. A cut-off
valve on some low flow shower heads allows the water to be turned off temporarily without the need
for adjusting hot and cold water.
TECHNOLOGY STATUS
Low flow shower heads and restrictors are fully developed technologically and readily avail-
able commercially (53, 17). Air assisted showers are fully developed, patented and available
commercially through one manufacturer.
APPLICATIONS
Low flow shower heads are applicable to residential and institutional water conservation.
Restriction devices cost less than shower heads and would be more applicable for community-
sponsored distribution programs where some of the devices may never be installed. Air assisted
showers would be used for maximum water (and energy) savings. Applications of the various low flow
showers are a function of their cost and the amount of flow reduction desired. Both restrictors
and shower heads operate at low pressures (20 psig to 40 psig) whereas the air assisted shower
operates at a minimum of 35 psig. The low flow shower heads perform better than the restrictors in
this pressure range.
LIMITATIONS
A drawback of the inexpensive restrictors is that they limit flows only to 3 gpm; a much
greater savings can be realized when the flow rate is reduced to 2 gpm or less. However, un-
acceptable showers result if these inexpensive flow restrictors limit flow to 2 gpm, especially at
pressures below 50 psig (73). This problem is less likely using low flow shower heads than using
restrictors. Air assisted showers require plumbing changes so that the air and water can be mixed
at the shower head. On the other hand, low flow shower heads and restrictors can be installed by
the homeowner without any major plumbing changes.
TYPICAL EQUIPMENT/NO. OF MFRS.
Shower Heads/25
External Restrictors/13
Internal Restrictors/20
Air assisted Showers/1
(61, 12, 55)
PERFORMANCE
California's Energy Resource Conservation and Development Commission (ERCDC) tested 13 shower
heads against a standard of a maximum flow rate of 2.75 gpm for line pressure between 20 and 45
psig and 3.0 gpm for a 45 to 80 psig line pressure. Of the 13 devices tested over a range
I-A-7
-------
FLOW REDUCTION - LOW FLOW SHOWERS
October 1980
FACT SHEET 1.4
of temperatures, 5 complied and 4 did not. The other 4 were marginal, either not complying for
particular temperatures or at high pressures (>74 psig). The greatest flow rate measured was 3.4
gpm in any of the tests.
Of the internal restrictors tested, only 4 out of 34 met the ERCDC criteria; the external
restrictors performed much better. Eight out of 9 met the established criteria satisfactorily,
although 5 had difficulty in conforming at the lowest temperature tested (76°F). A flow rate of
3.3 gpm was the highest of any of the 5 that did not conform at the lower temperature (12).
The manufacturer of air assisted showers claims that an average (4-person) household can save
88% of the shower water consumed yearly, thus reducing the shower sewage contribution by an equal
amount. Energy consumed by the air assisted shower is reported to be 86% of that consumed by
conventional showers (55).
RELIABILITY
Since restrictors, shower heads and air assisted showers operate, to some extent, by forcing
the water through a smaller opening, the possibility exists for dirt or rust to clog the openings.
The air assisted shower manufacturer recommends that a replaceable or cleanable filter precede the
shower head if dirt or rust is present in the water supply system. Air assisted showers rely on
electricity; shower heads and restrictors do not. The use of electricity and moving parts in the
air assisted shower motor indicates a lower reliability than shower heads and restrictors, which
have no moving parts and do not require electricity.
ENVIRONMENTAL IMPACT
Because of the water volume and heating energy savings, low flow shower heads and air assisted
showers offer more of an environmental benefit than other flow conservation devices. The greater
benefit is due to the increased energy savings as a result of using less hot water. Although no
reduction in pollutants is realized by these flow reduction devices, the lower hydraulic loading on
a soil absorption system can increase the potential for the soil to remove these pollutants more
effectively.
REFERENCES
61, 12, 53, 28, 73, 80, 55, 54, 58, 21, 57.
DIAGRAM
AIR
WATER
POWER UNIT
SHOWER
HEAD
EXTERNAL
FLOW RESTRICTOR
\
(12)
SHOWER
VALVE
INTERNAL
FLOW RESTRICTOR
(53)
AIR
ASSISTED
SHOWER
VARIABLE
ORIFICE
RESTRICTOR
(12)
(53)
I-A-8
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FLOW REDUCTION - LOW FLOW SHOWERS FACT SHEET 1.4
October 1980
ENERGY NOTES
The following table compares the various shower conservation devices with a conventional
shower and indicates the water and energy consumption of each. The assumed flow rates vary for
different line pressures and other individual circumstances. Hot water heater efficiencies also
vary depending on size, type, and other site-specific conditions. The object of the table is to
show relative differences, not absolute values.
NATURAL GAS HEATING OIL ELECTRICITY
Flow Water Million 1000CF Dollars Million Gallons Dollars Millions KWH Dollars
rate used Btus per per yr per yr Btus per per yr per yr Btus per per yr pec yr
(0PM) (1,000 yr yr yr
gal/yr)
Conven- 4 29.20 15.62 15.32 60 15.62 113 111 14.74 4319 172
tional
shower
Shower 3 21.90 11.70 11.48 45 11.70 84 83 11.69 3425 137
with
restrictor
Low flow 2 14.60 7.80 7.65 30 7.80 56 55 8.65 2534 101
shower
head
Air 0.5 3.65 1.95 1.91 8 1.95 14 14 4.08 1195 48
assisted
Assumptions
1) 4-person household, 1-five minute shower per person per day
2) Btu's required = Ibs water (AT) (Btu/lb water°F) T efficiency & standby loss, AT = difference
in shower water temperature and temperature of water entering water heater in °F (AT = 105°F
55°F = 50°F).
3) Gas and oil water heaters: Efficiency = 80%, standby loss = 3.17%
4) Electrical water heaters: Efficiency = 100%, standby loss = 2.56 million Btu's per year
5) 1 CF gas = 1019 Btu's
6) 1000 CF gas costs $3.939
7) 1 gallon oil = 138690 Btu's
8) 1 gallon oil costs $0.978
9) 1 KWH = 3413 Btu's
10) 1 KWH costs $0.04
COSTS
1980 dollars; ENR Index = 3260. Costs for low flow shower heads are in the range of $5 to
$20. Most restrictors cost from $1 to $5, and air assisted showers cost about $260 for all
necessary materials. Installation requires approximately 4 hours of a plumber's time which costs
$120 at $30/hour.
I-A-9
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FLOW REDUCTION - CHEMICAL TOILETS FACT SHEET 1.5
October 1980
DESCRIPTION
Chemical toilets are self-contained units that store human body waste in a storage chamber
along with either chemicals for odor control or enzymes for decomposition of waste. Some models
use no water for flushing, are portable, and are emptied directly into a conventional toilet or a
treatment facility. Flushing models use fresh or recirculated water to wash the waste into the
storage container. A foot-operated pump controls the flushing action. A variety of chemical
toilets is available, including models manufactured for permanent indoor residential use.
COMMON MODIFICATIONS
The number of uses prior to pumping is a direct function of the storage container size (and
the reservoir size for freshwater flushing models). The capacity can be extended by using addi-
tional holding vaults. Indoor installations are available with manual, electric (AC or DC) or
compressed air flushing (56).
TECHNOLOGY STATUS
Chemical toilets are fully developed technically. The chemicals used are biodegradable and do
not harm septic tanks or wastewater treatment plants (53, 56).
APPLICATIONS
Chemical toilets are designed primarily for recreational, marine and industrial applications.
Installations include airplanes, trains, buses, campgrounds, trailers, and others with portable and
permanent uses. Residential year-round applications require a sizeable storage vault to reduce the
pumping costs associated with removing the waste from the site.
LIMITATIONS
The main problem with chemical toilets for home use (other than possible code restrictions) is
the need for disposal of the chemical-waste mixture. The toilet system serves as a temporary
storage with disposal still necessary. The odor of the chemical might present problems indoors,
but go unnoticed in an outdoor environment. Chemical toilets do not make allowances for grey water
disposal and are not designed to receive any wastes other than excreta.
TYPICAL EQUIPMENT/NO. OF MFRS.
Chemical toilets/7 (53).
PERFORMANCE
United States Forest Service tests (35) on three models of chemical toilets indicate that the
models are satisfactory for forest service recreation sites. Although the testing was not directly
applicable to home use, it did indicate that the toilets' performance would be satisfactory.
RELIABILITY
Because of the high operation and maintenance (chemicals and pumping), the reliability would
be a function of user care and upkeep. The foot-operated type chemical toilet requires no energy
to operate and, therefore, functions during power failures as well as in areas where there is no
electricity.
ENVIRONMENTAL IMPACT
The environmental impact is beneficial from the standpoint of water conservation. However, an
adverse impact is caused by the need to haul the waste away from the site for treatment and dis-
posal. The possibility of leakage and spills exist. Use of chemical toilets on residential sites
over sensitive groundwater resources will substantially reduce bacteria and nitrate loads in house-
hold wastewaters.
REFERENCES
53, 56, 35.
I-A-10
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FLOW REDUCTION - CHEMICAL TOILETS
October 1980
FACT SHEET 1.5
DIAGRAM
CHEMICAL TOILET
CHEMICAL
RESERVOIR,
CHEMICAL
PUMP
HYDRAULIC FLUID
(ETHYLENE GLYCOL
AND WATER
SOLUTION)
METERED
CHEMICAL
BOWL
FOOT PEDAL
ACTUATOR
PUMP
FILTER/FLUSH
PUMP
PIN
FILTER
\
FILTERED
FLUSHING
FLUID
(56)
ENERGY NOTES
Manually operated toilets require no outside energy source for operation, however, the other
types would require energy in some form depending on the type of installation (electric - AC or
DC - or compressed air). Energy must be considered in the number of pumpouts (including hauling)
required yearly, the ultimate treatment and disposal of the stored waste, and the manufacture of
the required chemicals.
COSTS
1980 dollars; ENR Index = 3260. Capital costs for chemical toilets vary depending on size and
application. The range of these costs is $700 to $1,900. Additional storage tanks would increase
the costs.
OPERATION AND MAINTENANCE
Operation and maintenance costs are greater for chemical toilets than for conventional
toilets. The major considerations are adding the chemicals and pumping the chemical wastes. For
example, an indoor year-round chemical toilet that provides up to 1,000 uses for a family of three
may have to be pumped five or six times per year. At $50 per pumping, the annual costs could be
from $250 to $300 per year plus chemical costs. One gallon of chemical is required for 1,000
flushes, implying five to six gallons of chemical per year, which would cost from $42 - $50 and
would bring the total annual operation and maintenance costs to $292 - $350 in this example. The
use of a storage vault, the number of users, and the local cost of pumping would all affect the
annual operation and maintenance costs.
I-A-H
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SEPTIC TANK MODIFICATIONS FACT SHEET 2.1
October 1980
DESCRIPTION
1) Multiple Tanks or Chambers: An improvement to the conventional septic tank is the use of
two or more compartments within a septic tank or two or more septic tanks in series. The purpose
of the additional chamber(s) is the reduction of solids carry-over into the drainfield along with
the prevention of short circuiting.
2) Baffles: Baffles inside the septic tank provide for proper settlement of solids and
retention of scum, and prevent short circuiting. The inlet baffle directs the sewage downward and
prevents the scum layer from clogging up the inlet pipe. The outlet baffle helps to retain sludge
and scum in the tank thus preventing drainfield clogging.
3) Septic Solids Retainer: This outlet device is designed to allow fewer solids out of the
tank by using a bell-shaped outlet pipe equipped with an insert to keep scum and solids in the
tank.
COMMON MODIFICATIONS
1) Compartmentalization can be achieved by adding additional septic tanks or by using a
baffle in one tank with a horizontal opening below the scum level to allow clarified effluent to
flow into the second compartment.
2) Baffles can vary in location, shape, and size but should follow recommended criteria in an
accepted reference (48).
3) A septic solids retainer can be installed in combination with either of the above two
modifications for increased solids retention.
TECHNOLOGY STATUS
1) Available research data indicates that two-compartment tanks provide an extra degree of
suspended solids removal (76). Some state guidelines recommend dual compartment septic tanks (62)
which indicates the acceptance of the technology.
2) Baffles are well accepted modifications of septic tanks and are required in many areas.
3) The septic solids retainer is a relatively new device designed to keep more solids in the
septic tank and out of the drainfield.
APPLICATIONS
1) Multi-compartment septic tanks can be used with newly constructed systems when solids are
anticipated to be a problem, or to lessen the solids load on the drainfield even if excessive
solids loading is not expected.
2) Baffles should be an integral part of all new septic tanks. Inlet and outlet baffles can
prevent septic tank drainfield problems and should therefore be replaced if damaged or missing from
existing tanks.
3) Septic solids retainers may be retrofitted to existing septic tanks or installed in new
ones.
LIMITATIONS
1) If a single tank is divided into compartments or if multiple tanks are used, adequate
ventilation is necessary to allow the escape of gases produced by the anaerobic decomposition
process (48). The material used to divide a septic tank into compartments should not be subject to
the corrosive nature of the septic tank environment.
2) Baffles are subject also to corrosion and should be sized and placed according to
recommended guidelines. Fiberglass and acid-resistant concrete are suitable materials; metal
baffles corrode easily.
I-A-12
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SEPTIC TANK MODIFICATIONS FACT SHEET 2.1
October 1980
3) The septic solids retainer may have a tendency to clog the outlet due to its restrictive
nature. Regular septic tank maintenance, however, should avoid this problem. A septic solids
retainer by itself cannot rehabilitate a failed system.
TYPICAL EQUIPMENT/NO. OF MFRS.
1) Multiple tanks or built-in baffles would be constructed by the local septic tank supplier.
2) Baffles can be built-in by the septic tank supplier or installed by the contractor or
homeowner with materials supplied locally.
3) There is only one manufacturer for the septic solids retainer.
PERFORMANCE
1) In the research available, some authorities suggest that multiple tanks provide better
treatment than single tanks. Although no studies have been extensive enough to provide definitive
conclusions, many septic tank guidelines suggest the use of more than one chamber. Additional
capacity along with walls or baffles appear to provide a greater opportunity for solids to settle
out and thus reduce their presence in the soil absorption system (71, 8, 85, 96).
2) Baffles constructed of the proper materials have proved to be an effective aid to the
septic tank process that retains scum and prevents short circuiting.
3) In the testing performed by the National Sanitation Foundation, the septic tank with the
septic solids retainer removed 30 to 35 percent more solids than the control septic tank.
DESIGN CONSIDERATIONS
1) The first compartment (or tank) should be between 1/2 and 2/3 of the total required volume
(32, 48, 96).
2) "The inlet baffle must be submerged at least 6 inches below the liquid level but must not
penetrate any deeper than 20% of the liquid depth...the bottom of the outlet baffle must be sub-
merged at a point which is equal to 40% of the liquid depth of the tank." Both baffles should
extend 20% of the liquid depth above the liquid level for scum storage (48).
3) The design considerations for the septic solids retainer is handled by the manufacturer.
RELIABILITY
1) The reliability of dual tanks is the same as for a single tank provided proper connections
and adequate ventilation are provided. Increased solids storage adds to the reliability of the
overall system.
2) The reliability of baffles is related to proper placement and choice of materials. Outlet
baffles must allow for gaseous exchange with the remainder of the tank.
3) The septic solids retainer has no moving parts and is made of a non-corrosive high density
polyethylene which should provide reliable service although no long-term data is available.
ENVIRONMENTAL IMPACT
By improving the operation of conventional septic tank soil absorption systems without added
operational costs, a positive environmental impact will be achieved in the form of reduced failure
rates of subsurface soil absorption systems.
APPLICATION TO CLUSTER SYSTEMS
Cluster systems that operate by using individual septic tanks followed by a community treat-
ment process benefit from the additional treatment provided by multiple chambered septic tanks,
baffles, and the septic solids retainer.
I-A-13
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SEPTIC TANK MODIFICATIONS
October 1980
FACT SHEET 2.1
REFERENCES
8, 71, 48, 85, 76, 32, 60, 96, 24, 62, 49.
DIAGRAM
COMPARTMENTED SEPTIC TANK WITH BAFFLES
,:.".-.-'• (49)
SEPTIC SOLIDS RETAINER
INLET,- -
DEFLECTS
SETTLING
SOLIDS
ENERGY NOTES
RISING 8 SETTLING
PARTICLES
(60)
None of the three modifications discussed requires energy input after initial installation.
COSTS
1980 dollars, ENR Index = 3260
1) Capital costs for an additional septic tank would range from $350 to $750.
2) Many septic tanks are built with the baffles included. The costs of installing them
should not exceed the cost of building a water-proof wall to section off a septic tank into com-
partments.
3) Septic solids retainers cost about $30 each with bulk discounts available.
OPERATION AND MAINTENANCE
There are no operation and maintenance requirements after installation of any of the
modifications mentioned above.
I-A-1A
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GRAVITY DISTRIBUTION FOR SOIL ABSORPTION SYSTEMS FACT SHEET 2.2
October 1980
DESCRIPTION
Gravity distribution of septic tank effluent to a soil absorption system is the most common
and least energy intensive method of applying wastewater to subsurface drainfields. Many methods
of effluent distribution exist using various appurtances, some of which are described below.
1) Parallel Distribution is the most, widely used method of gravity distribution for soil
absorption systems. Both trench and bed designs fall into this category. Trenches are usually one
to five feet deep and one to three feet wide. Perforated distribution piping is laid on top of a
six-inch-deep layer of washed, crushed rock or gravel. Additional gravel is placed on top of the
piping followed by material which keeps the dirt backfill from penetrating the rock. A series of
these trenches constructed parallel to each other comprise the entire system. Beds differ from
trenches in that the excavation is wider than three feet and contains several lines of distribution
piping. Absorption beds require less room than trenches. Distribution lines in beds should be
placed from four to six feet apart and from \\ to three feet from the sides of the excavation.
2) Distribution Boxes are used between the septic tank (or other treatment unit) and the
drainfield distribution lines to divide the effluent evenly among all distribution lines. The box
has one inlet and multiple outlets, one for each line in the distribution network. All the outlets
should be at exactly the same elevation and slightly below the inlet elevation.
3) Serial Distribution is a method of loading a drainfield so that the first trench is used
to capacity before the second trench is loaded. This is accomplished by using plastic fittings or
drop boxes at the head or the middle of each trench. Plastic fittings join distribution lines such
that the opening to the second trench is at a higher elevation than the capacity level of the first
trench. Because the outlet to subsequent trenches is at a higher elevation than the "capacity
level" of the trench being filled, the subsequent trenches are not filled until the first trenches
are fully utilized.
4) Drop Boxes are round or square boxes with removable covers containing an inlet, distribu-
tion lateral(s), and an overflow. The boxes are used for serially loaded trenches distributing
wastewater through the distribution laterals until the water level reaches the overflow elevation.
The overflow line then becomes the inlet for the next drop box in the series.
5) Dosing Siphons are gravity-operated devices that deliver wastewater to a soil absorption
system in periodic slugs instead of at a constant trickle. A dosing siphon contains a chamber that
fills up with effluent from the treatment unit to a predetermined level and then empties, dosing
the entire drainfield.
6) Alternating Drainfields involve two drainfields that operate independently of each other
but receive effluent from a common tank through a diversion valve. The diversion valve can direct
the flow to either drainfield so that, while one is in operation, the other is resting.
7) Large Diameter Distribution Tubing is ten inches in diameter compared to four inches for
standard distribution pipe. The drainage openings are in the sides of the large pipe to facilitate
additional solids settling within the distribution system. An inspection port or a pump is pro-
vided at the end of the soil absorption trench to monitor the solids accumulation and to allow the
system to be flushed when solids deposition reaches a certain level (1).
8) Vents (or breathers) are installed at the ends of trenches xn soil absorption systems to
provide a more aerobic environment in the drainfield. Vents consist of a vertical pipe extending
from the bottom of the drainfield above ground and covered with a vent cap. The portion of the
pipe located in the porous media section of the drainfield is usually perforated so that the liquid
level can be observed (64).
COMMON MODIFICATIONS
1) Parallel Distribution can be modified by connecting the ends of the distribution lines
with additional perforated piping to form a closed loop system. Septic tank effluent can reach any
point in the drainfield by one of several routes. This modification avoids under utilization of
drainfields when local blockages occur. Closed loop systems function properly when constructed on
a level site and connected to the septic tank through a level cross, tee, or distribution box.
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GRAVITY DISTRIBUTION FOR SOIL ABSORPTION SYSTEMS FACT SHEET 2.2
October 1980
2) Distribution Boxes can be designed to feed two or more trenches or more and can load the
trenches from the center or the ends. Distribution boxes can be either round or rectangular and
should have a removable cover to observe problems (24, 71). Construction can be concrete, brick or
fiberglass and may contain a baffle if high velocities are expected.
3 & 4) Serial Distribution and Drop Boxes can be used with either continuously-ponded or dosed
drainfields. For dosed systems, or where inlet velocities are high, a baffle should be used to
ensure that! the trenches fill before the wastewater flows out of the drop box.
5) Siphon Dosing can be accomplished with either a bell or a V-shape siphon. The amount of
volume to be applied can be changed by altering the size of the dosing chamber.
6) A common modification of an Alternating Drainfield involves sizing three separate fields
instead of two. Each field is sized to accept 50% of the flow and two are kept in operation con-
tinuously while the third is rested.
7) Large Diameter Distribution Tubing with outlet holes located on the sides can drain into a
conventional rock-filled trench or can be covered with a special fabric and can leach directly into
the soil. The fabric provides filtration of the effluent and keeps the backfill material from
entering the pipe while allowing the effluent to leach into the soil (1). A system called the
Sheldon Network, which uses small diameter distribution tubing with the holes located on the top of
the pipe, utilizes the idea of additional settlement within the drainfield tubing prior to soil
absorption (75).
8) Vents can allow air to enter the drainfield by providing a connection to the drainfield
from above ground. More air is allowed in the system if an inlet is provided at the end of the
trench and an outlet vent is connected to the top of the septic tank. In addition, the outlet vent
can be connected to a windpowered turbine on the roof of the house, which would induce fresh air
while removing the gaseous build up in the drainfield and the septic tank (1).
TECHNOLOGY STATUS
All of the devices and techniques discussed here are proven and fully developed technologies,
with the exception of large diameter distribution tubing which has only been available since 1978.
APPLICATIONS
1) Parallel Distribution has many applications for rural areas where soil characteristics are
favorable such that higher cost alternatives are not necessary.
2) Distribution Boxes are used with conventional soil absorption systems to maintain equal
flow to all distribution lines. Depending on the number of lines to be fed, the distribution box
must be designed for site-specific circumstances.
3 & 4) Serial Distribution networks are used on level ground but are most useful on steep sites
where parallel distribution results in overloading the bottom trench. Trenches follow contours of
the land so that each trench stays level throughout its length. An advantage of serially-loaded
systems is that additional trenches may be readily added to expand the system without disturbing
the existing treatment process.
5) Siphon Dosing is used when a more even distribution over the entire drainfield is desired.
Periodic dosing allows for resting of the system which creates more aerobic conditions leading to
quicker decomposition of the biological mat that forms at the infiltrative surface.
6) Alternating Drainfields are useful wherever regular soil absorption systems are installed,
providing enough land area is available. In addition to allowing a year-long resting period every
other year, alternating drainfields also provide an emergency backup field in case the field in use
should fail.
7) Because the main advantage of Large Diameter Tubing is its capacity to settle out addi-
tional solids, a prime site for application is where excessive solids are expected (e.g., a home
with a garbage disposal). Systems with large diameter pipe and fabric covering that do not utilize
I-A-16
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GRAVITY DISTRIBUTION FOR SOIL ABSORPTION SYSTEMS FACT SHEET 2.2
October 1980
gravel in the trenches are easier to install, although care must be taken to maintain the proper
slope and orientation of the holes. Another application is where an underlying bedrock or ground-
water layer prohibits the use of a system that requires more depth for installation.
8) Vents are used with almost any type of soil absorption system. A major advantage to
having properly installed vents is the ability to monitor the system by checking the level of the
wastewater above the infiltrative surface.
TYPICAL EQUIPMENT/NO. OF MFRS.
Most of the material and equipment needed for the techniques discussed is locally available.
Siphons and large diameter tubing are modifications that require specialized equipment usually
available through the manufacturer's representative. Residence size siphons are available from at
least two manufacturers. Large diameter tubing is available only from one manufacturer.
PERFORMANCE
The performance of any system depends on the site conditions, installation procedures, and
user maintenance. If the treatment system is not located on a site with suitable soils or topo-
graphy, the chances for good performance are poor. Similarly, construction procedures can produce
detrimental effects throughout the life of the system, such as the compacting effect of heavy
equipment on underlying soils or the overloading of areas of soil absorption systems due to poor
distribution box installation. Maintenance of on-site systems is also a major factor in system
performance; for example, septic tanks that are not pumped will eventually cause solids to carry
over to the absorption field leading to system failure.
1) Parallel Distribution performs well when properly sited, installed and maintained. Pol-
lutant removals are satisfactory with the exception of nitrates and chlorides in coarse aerated
soils. Viruses, BOD, suspended solids, bacteria, and complex organic compounds undergo adsorption
and biological degradation in the soil so that the groundwater is protected.
2) Performance of Distribution Boxes has been less than adequate. The U.S. Public Health
Service discarded this technique because of poor distribution and subsequent under utilization of
drainage field capacity (65).
3 & 4) SerialDistribution has proven to be a satisfactory method of effluent disposal. Some
states consider Drop Boxes and serial distribution to be the most desirable method to distribute
effluent (48).
5) Dosing Siphons perform well enough to be required for soil absorption systems over a
certain size in some states (46). They are well accepted because of their satisfactory per-
formance.
6) The performance of Alternating Drainfields is a function of the design, construction, and
maintenance of the individual soil absorption systems. No performance problems have been noted
with the diversion valves, and other components of the system are the same as conventional soil
absorption systems that function well if properly designed, installed and operated.
There is not enough information available to judge the performance of Large Diameter
8) Vents perform satisfactorily for systems that are not continuously ponded. As a monitor-
ing device, vents operate well if constructed so that the bottom of the trench is visible from the
ground surface.
DESIGN CONSIDERATIONS
1) Parallel Distribution systems should not be installed in soils with a coarse sand or
gravel texture of percolation rates faster than .1 min/in. Silty clay loams or clay loams with
percolation rates min/in should not be used either for conventionally designed trench or bed soil
absorption systems. The following table gives guidelines for domestic wastewater application rates
for different soil textures and percolation rates (71):
I-A-17
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GRAVITY DISTRIBUTION FOR SOIL ABSORPTION SYSTEMS FACT SHEET 2.2
October 1980
PERCOLATION RATE APPLICATION RATE
SOIL TEXTURE (MIN/IN) (GPD/SF)
Coarse to Medium Sand 1-5 1.2
Fine Sand, Loamy Sand 6-15 0.8
Sandy Loam, Loam 16-30 0.6
Loam, Porous Silt Loam 31-60 0.45
2) Distribution Boxes should be designed so that all outlet pipes are at the same elevation
and the invert of the inlet pipe is at least one inch above the invert of the outlets. The water-
tight outlet pipes should have equal slopes for five feet after leaving the box, and each trench
should be connected individually to the distribution box. The cover for the distribution box
should be removable and a baffle should be installed in front of the inlet pipe when the velocity
of the influent is expected to be high (49).
3 & 4) For Serial Distribution, Drop Boxes offer many advantages over water-tight pipe for dis-
tributing the effluent to individual trenches. Drop Boxes are usually 12 to 18 inches in diameter,
and are square. The overflow invert should be at the same elevation as the crown of the distribu-
tion laterals or two inches above it so that the full depth of the trenches is flooded. If the
overflow invert elevation is near the top of the rock surface in the trench, the entire trench
sidewall will be used, maximum hydrostatic head will be developed on the trench bottom, and a
constant supply of liquid to the capillary pores in the soil will maximize soil evaporation and
plant utilization. The inlet invert may be at the same elevation as the outlet invert or a few
inches higher (48, 71).
5) The main criteria for Dosing Siphons is the amount of waste to be delivered to the absorp-
tion field. This volume is determined by the size of the dosing chamber. A drainfield should not
be dosed more than four times per day. The volume of each dose shall be the greater of 1) the
daily wastewater volume divided by the daily dosing frequency or 2) an amount approximately equal
to 3/4 of the internal volume of the distribution lines being dosed (32).
6) Alternating Drainfields should follow the design criteria for conventional soil absorption
systems for both fields. The diversion valve should be of a corrosion resistant material and
should be accessible from the ground surface for the annual changing of drainfields.
7) For the design of drainfields with Large Diameter Tubing the manufacturer's recommenda-
tions should be followed. For systems without gravel in the trenches, these recommendations in-
clude having approximately 12 inches of cover and being laid on a slope of 0 to ^ inch per foot of
length. Also provisions must be made for washing out the solids that build up in the bottom of the
pipe (1).
8) Vent Pipes should be a minimum of 4 inches in diameter and can be connected to the distri-
bution pipe at the end of a trench with a fitting or a junction box. The vent should extend at
least 12 inches above the finished grade and terminate with a vent cap. Below the connection to
the distribution pipe, the vent pipe should extend to the bottom of the excavation with perforated
pipe. Vents should be located at least 25 feet from any windows, doors, or air intakes for build-
ings (106).
RELIABILITY
1) Parallel Distribution is a reliable method of dispersing septic tank effluent to the soil.
Systems properly constructed and maintained have provided useful service for more than 20 years.
2) Distribution Boxes are not reliable because of the requirement for keeping all the outlet
inverts at the same elevation. Improper backfilling or differential settling over time are often
reasons for distribution boxes to favor one line over others, resulting in possible system failure.
3 & 4) The reliability of Serial Distribution of effluent is greater than that for conventionally
loaded systems. If the first trenches in the system fail due to clogging, the remainder of the
system can still be used. The ability to rest individual trenches by plugging the distribution
laterals from the Drop Boxes gives the system an added degree of reliability.
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GRAVITY DISTRIBUTION FOR SOIL ABSORPTION SYSTEMS
October 1980
FACT SHEET 2.2
5) The addition of mechanical equipment such as a Dosing Siphon often reduces the reliability
of the overall system. However, dosing increases the reliability of the drainfield because failure
by clogging is less likely when aerated conditions are established between applications. Overall
reliability is therefore increased over systems that are not dosed.
6) Alternating Drainfields are more reliable than systems with only one drainfield. Resting
the individual drainfields provides one aspect of the increased reliability while having an emer-
gency back-up field provides another.
7) Although little data exists, the increased solids retention in Large Diameter Tubing
provides for a more reliable system.
8) Vents are more reliable for monitoring than for providing an aerobic environment in con-
tinuously ponded systems. The air entering vents is more effective in gravity dosed systems.
ENVIRONMENTAL IMPACT
Subsurface disposal systems provide sufficient filtration, adsorption, and microbial degrada-
tion of harmful constituents in household effluent. System failures, however, can occur and are
related to site limitations or to improper installation, operation, or maintenance. Adverse envi-
ronmental effects attributed to failures of subsurface disposal systems generally involve the con-
tamination of ground or surface waters. This contamination then may result in public health
hazards if drinking water is affected or in accelerated eutrophication if excessive amounts of
nutrients are delivered to lakes or streams.
Mitigation and avoidance of adverse environmental impacts depend on information regarding site
specific conditions that led to system failures in the community, the use of this information to
select repairs and replacement systems and to design new systems.
APPLICATION TO CLUSTER SYSTEMS
For large septic tank/soil absorption systems such as those used for multiple residences,
gravity systems may not adequately distribute the effluent. However, dosing (gravity or pumped)
and alternating drainfields can work well with larger systems. The additional maintenance required
for dosed and alternating drainfields becomes more important as the risk for groundwater pollution
increases with the size of the system.
REFERENCES
48, 64, 101, 44, 46, 31, 71, 76, 85, 32, 106, 24, 10, 49, 1, 75, 65, 109.
DIAGRAM
USE OF PLASTIC FITTINGS
FOR SERIAL DISTRIBUTION
PERFORATED
PIPE
SOIL ABSORPTION
SYSTEM TRENCH
(101)
I-A-19
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GRAVITY DISTRIBUTION FOR SOIL ABSORPTION SYSTEMS
October 1980
FACT SHEET 2.2
DIAGRAM
INLET SEWER
SEPTIC TANK FOLLOWED BY GRAVITY DOSING SIPHON
BAFFLE
BAFFLE
JDISCHARGE PIPE
(109)
VENT OBSERVATION PIPE
APPROVED VENT CAP
MINIMUM 12" ABOVET
FINAL GRADE |
BACKFILL
,^-MARSH HAY OR
1 SYNTHETIC
COVERING
DISTRIBUTION j
PIPE '
AGGREGATE
OVER PIPE
QCMCATU^D
BENEATH PIPE
4" CAST IRON VENT PIPE
OPTIONAL CONNECTION
-DISTRIBUTION PIPE
USING TEE
PERFORATED PIPE BELOW
-COUPLING TERMINATING AT
BOTTOM OF EXCAVATION
(106)
PARALLEL DISTRIBUTION WITH
DISTRIBUTION BOX AND TRENCHES
DISTRIBUTION
BOX
\
iS \
.
1
1
/
\ATLEAST,'
'4 1/2' OF \
UNDISTURB-
ED EARTH 1
1 1
1 1
Ha / >--> 1
\ V ^
\ \
| i
1
1
\
\ /•
\\
1 1
II '
J
4
4" WATER-TIGHT
PIPES
4"DISTRIBUTIOIN
PIPES INTRENCHES
(49)
I-A-20
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GRAVITY DISTRIBUTION FOR SOIL ABSORPTION SYSTEMS
October 1980
FACT SHEET 2.2
PARALLEL DISTRIBUTION USING
CLOSED LOOP SYSTEM FOR
LEVEL GROUND
DISTRIBUTION PIPES CAN BE
4" PERFORATED PLASTIC OR
SPECIAL QUALITY AGRICULTURAL
DRAIN TILE IN l' LENGTHS
SERIAL DISTRIBUTION
OF EFFLUENT
>ROP
BOXES
(49)
ENERGY NOTES
None of the systems or devices discussed above requires any energy input after initial in-
stallation.
COSTS
1980 dollars; ENR Index = 3260. The costs presented are those that can be expected for the
construction of an entire on-site system for a 3-bedroom house unless otherwise noted.
1 & 2) Parallel distribution with a distribution box
3 & 4) Serial distribution with drop boxes
5) Dosing siphons (siphon and chamber installed)
6) Valves for alternating drainfields
7) Large diameter tubing costs $2.10/LF the total system costs are
lower than for a conventional ST/SAS if local gravel costs exceed
$10 - $12 per cubic yard (personal communication with Tim Lang, ADS -
8/11/80).
8) Vents (each)
OPERATION AND MAINTENANCE
$1,500 to $3,000
$1,700 to $3,000
$ 400 to $ 650
$ 50 to $ 80
$ 75 - $ 100
Operational costs for all gravity fed systems would be a function of septage pumping every
three to five years. An annual cost of $15 to $25 can be expected. Other routine 0 & M operations
could be performed by the homeowner such as turning the valve on alternating systems or cleaning
the dosing siphon. The actual infiltrative surface of the drainfield also should be checked
periodically, perhaps when the tank is pumped.
I-A-21
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SOIL ABSORPTION SYSTEMS - PRESSURE DISTRIBUTION FACT SHEET 2.3
October 1980
DESCRIPTION
Pressure distribution is a method of applying effluent to soil absorption systems using a pump
and usually small diameter pipe with drilled holes. The system includes the idea of dosing with
uniform distribution of effluent. The pressure maintained at the end of the lateral farthest from
the manifold connection is about 1 to 2 psi during operation.
COMMON MODIFICATIONS
Pressure distribution systems with small diameter distribution pipes can be used with deep or
shallow installations and can be recommended for use with mound systems. Pumps following septic
tanks can be used to pump the effluent to a distribution box (or header) followed by a gravity
distribution soil absorption system.
TECHNOLOGY STATUS
Although pressure distribution networks have not been used for very long, they are a fully
developed and acceptable method for effluent distribution.
APPLICATIONS
Pressure distribution is useful for any situation where uniform application of effluent is
desirable, such as with highly permeable soils to prevent saturated flow and with moderately to
slowly permeable soils to retard clogging (96). Another application is for large absorption areas
to ensure that the field capacity is utilized fully.
LIMITATIONS
To achieve uniform distribution, more attention must be given to the design and construction
of pressure distribution systems than to conventional gravity systems. Also, pump failure would
have to be repaired within a short time to keep wastewater from backing up into the house (85).
TYPICAL EQUIPMENT/NO. OF MFRS.
Small pumps (1/3 to 1/2 hp) and 1-3 in. PVC piping are supplied locally along with pump
chambers. Holes in the PVC pipe are usually drilled by the contractor.
PERFORMANCE
Performance of pressure distribution systems is good providing that the pump is sized pro-
perly; undersizing of the pump can lead to hole clogging and sludge accumulation (19). Removing
the burrs from the drilled holes prevents solids buildup and reduces head loss across the openings
in the laterals.
DESIGN CONSIDERATIONS
Site-specific designs are required for each system depending on the layout of the trenches and
the absorption field area requirements. To achieve uniform distribution, the volume of effluent
flowing from each hole in the network should be the same. The head losses should therefore be
balanced such that 75 to 85 percent of the total head loss occurs crossing the orifice, and the
remaining 15 to 25 percent occurs in delivering the wastewater to each hole. The networks usually
consist of laterals from 1 to 3 inches in diameter with a larger center or end manifold. The
laterals are perforated at the invert with 1/4 to 1/2 inch holes spaced from 2 to 10 feet (71).
Dosing volumes should be 10 times the total pipe volume and a minimum of 75 gallons. Dosing fre-
quency should not exceed 4 times/day.
RELIABILITY
Pressure distribution networks are dependent on electricity for operation and are therefore
subject to losses of power. The pump itself may fail if not checked periodically for proper opera-
tion. An indoor alarm indicating pump failure and/or high water level in the pumping chamber
increases the reliability of the overall system. Replacement pumps should be readily available.
I-A-22
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SOIL ABSORPTION SYSTEMS - PRESSURE DISTRIBUTION
October 1980
FACT SHEET 2.3
The pipe system should be installed so that after the pumping cycle, the wastewater remaining in
the pipe drains back to the pumping chamber.
ENVIRONMENTAL IMPACT
Subsurface disposal systems can provide sufficient filtration, adsorption, and microbial
degradation of harmful constituents in household effluent. System failures, however, can occur and
are related to site limitations or to improper installation, operation, or maintenance. Adverse
environmental effects that are attributed to failures of subsurface disposal systems generally
involve the contamination of ground or surface waters. This contamination then may result in
public health hazards if drinking water is affected or if nutrients are delivered to lakes or
streams.
Mitigation and avoidance of adverse environmental impacts depend on information regarding site
specific conditions that led to system failures in the community, and the use of this information
to select repairs and replacement systems and to design new systems.
APPLICATION TO CLUSTER SYSTEMS
Pressure distribution is readily adaptable to cluster systems where subsurface application of
wastewater is used. The advantage of pressure distribution for large fields is that the entire
field is used. The idea of using alternating drainfields with pressure distribution has great
potential for cluster systems.
REFERENCES
65, 19, 85, 71, 96, 24, 48, 49, 94.
DIAGRAM
LAYOUT OF PERFORATED PIPE LATERALS FOR
PRESSURE DISTRIBUTION
END
VIEW
PERFORATED PLASTIC PIPE
PERFORATIONS SPACED 2'TO 10'
ON CENTER. PERFORATION
SIZE VARIES.
PERFORATIONS ON BOTTOM
OF PLASTIC PIPE
PIPE FROM
PUMPING CHAMBER
(49)
I-A-23
-------
SOIL ABSORPTION SYSTEMS - PRESSURE DISTRIBUTION
October 1980
FACT SHEET 2.3
PUMPING CHAMBER FOR
PRESSURE DISTRIBUTION SYSTEM
PIGGY BACK PLUG IN WEATHER
PROOF ENCLOSURE-OR LOCATE-
IN MOUSE BASEMENT
ALARM WIRE
MANHOLE COVER SECURED
TO PREVENT UNAUTHORIZED
ENTRY
FROM
SEPTIC
TANK
POWER SUPPLY
CONTROL WIRE
PUMPABLE?
CAPACITY
AT LEAST
75 GALLONS.*.
ALARM FLOAT
ON SEPARATE
ELECTRICAL
CIRCUIT
RESERVE CAPACITY
AFTER ALARM SOUNDS
$ -UNION OR OTHER '.
.QUICK DISCONNECT
FITTING' ' . '
TO SOIL .
TREAT
AREA . -
1/4" WEEPHOLE FOR
DRAINBACK, OR
CHECK VALVE MAY
BE INSTALLED IF
PIPE TO TREATMENT
AREA IS FROST PROOF
(49)
ENERGY NOTES
Electricity is required to operate the pump for pressure distribution systems. A 1/3 to 1/2
HP motor is required to operate from 1 to 4 times daily. The amount of energy required is minimal
for such small motors and infrequent use varying flow 50 to 250 KWH/yr (94).
COSTS
1980 dollars; ENR Index = 3260. Installed costs for an individual pressure distribution
system (assuming a 3-bedroom house) are from $3,000 to $4,000 including septic tank, pump, pump
chamber, and soil absorption system. The cost for a pump and pumping chamber to raise the effluent
from a septic tank to a gravity fed distribution system is $400 to $600 installed.
OPERATION AND MAINTENANCE
Operating costs include pump maintenance and power along with septic tank pumping (every 3 to
5 years). These costs are in the range of $35 to $75 per year.
I-A-24
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SOIL ABSORPTION SYSTEMS FOR HIGH GROUNDWATER OR SHALLOW SOILS FACT SHEET 2.4
October 1980
DESCRIPTION
Soil absorption systems that are designed to deal with high groundwater, shallow soil over
rock, or impermeable layers include mounds, shallow placement, and artificial drainage.
Mound Systems consist of a septic tank, a pumping chamber, and pump that lifts the effluent to
a raised absorption bed constructed over original ground surface. The raised bed is constructed of
a suitable fill material, a gravel absorption area, pressurized distribution pipe, an impermeable
soil cap, and topsoil for a vegetative cover.
Shallow Placement Systems are distribution networks that are installed in the upper soil
horizons. Distribution pipe may be either gravity (4" perforated) or pressurized (IV or 2" PVC).
The actual depth of installation is dictated by site constraints. The shallowest systems are dug
through fill to use original ground surface as the trench bottom. Varying amounts of fill are
required for deeper systems.
Artificial Drainage makes sites usable for soil absorption systems that would otherwise be re-
stricted by the presence of groundwater. Artificial drainage is used to lower perched or seasonal
water tables to make sites amenable to soil absorption systems; however, regional (year round)
groundwater levels should not be altered for this purpose (33). Plume recovery is an innovative
method of artificial drainage use in moderately to highly permeable soils where effluent plumes
from existing drainfields discharge nutrients to lakes or streams. A shallow recovery well or line
of wells intercept plumes and return the mixed effluent and groundwater to lawns or gardens for
irrigation.
COMMON MODIFICATIONS
Although Mound Systems are constructed usually using pressure distribution systems, a dosing
siphon can be used if enough elevation head is available. Distribution layouts can take the form
of trenches or beds (20).
Shallow Placement Systems can use different distribution methods such as trenches, serial
distribution, or beds. Shallow systems can be combined with dosing and artificial drains. Depth
and shape of trenches can be varied as suitable for individual sites. V-shaped trenches can be
used to increase the sidewall surface area. Another technology adaptable to shallow placement is
large diameter drainfield distribution piping (see Fact Sheet 2.2, GRAVITY DISTRIBUTION FOR SOIL
ABSORPTION SYSTEMS).
Three commonly used Subsurface Drainage techniques include vertical drains, curtain drains and
underdrains (see diagram). Curtain and vertical drains are used to lower perched water tables and
underdrains are used to lower water tables in permeable soils. Construction is similar for these
types of drains but spacing and depth requirements are dictated by the soil and groundwater charac-
teristics of the site (71).
TECHNOLOGY STATUS
Elevated sand Mounds have been undergoing modifications and improvements since the 1940's when
the first system was installed; they are now considered to be fully developed. Design and con-
struction errors made in the past have been evaluated, and appropriate remedies have been included
in current construction guidelines.
Shallow Placement Systems vary from conventional soil absorption systems primarily in depth.
The technology for shallow systems can therefore be considered fully developed, although installa-
tion and evaluation in a range of settings have not been reported.
"The technology of using Drain Tile for agriculture and footing drainage is well developed,
and can be adapted easily to on-site systems." (33). However, installation and evaluation in a
range of settings have not been reported.
APPLICATIONS
Mounds are used to overcome site limitations such as high groundwater tables, confining soil
or creviced bedrock layers, very permeable soils, and soils of low permeability.
I-A-25
-------
SOIL ABSORPTION SYSTEMS FOR HIGH GROUNDWATER OR SHALLOW SOILS FACT SHEET 2.4
October 1980
Shallow Placement Systems are appropriate for soils with slowly permeable subsoil or parent
material horizons or where maximum separation from groundwater is sought. Using upper soil layers
rather than underlying soil layers takes advantage of more permeable soils, plant and soil fauna
activity, greater evapotranspiration, and quicker drying (96, 2).
Lowering the groundwater by Artificial Drainage is useful for intercepting a laterally moving
perched water table caused by a shallow impermeable layer (curtain drain), or caused by a thin,
shallow, impermeable layer (vertical drain). A curtain drain intercepts perched groundwater
through the use of a pipe located in gravel at or above the impermeable layer, whereas a vertical
drain is constructed of gravel (without a pipe) that goes through the thin impermeable layer allow-
ing the groundwater to enter permeable soil below the impermeable layer. Underdrains are used to
lower seasonally high groundwater (71). Plume recovery is appropriate primarily for existing
systems near lakes to mitigate growth of aquative plants.
LIMITATIONS
Elevated Sand Mounds should not be constructed in areas where groundwater level, bedrock, or
other strata having a percolation rate slower than 120 minutes per inch are located within 24
inches of the natural grade. Also, mounds should not be located in floodplains, poorly drained,
very poorly drained or stoney soils (as defined by the Soil Conservation Service) (32). Maximum
slopes for mounds are 6% for soils with percolation rates between 30 to 120 minutes per inch, and
12% for percolation rates of 0 to 30 minutes per inch (106).
Shallow Placement Systems should not be used if the side wall of a deeper system would have a
better infiltrative surface or if more permeable soils exist deeper. Freezing of shallow systems
not continuously used should also be considered (96).
Artificial Drainage of groundwater is not practical in fine textured soils of slow per-
meability, areas where artesian aquifers exist, or in soils that are saturated for long periods of
time, especially level sites. Local codes restricting artificial drainage should also be consulted
(71, 106). The irrigation system for effluent plume recovery would be subject to freezing if a
constant flow of water through the nozzles was not maintained.
TYPICAL EQUIPMENT/NO. OF MFRS.
All of the techniques discussed here are available through local septic tank installers.
PERFORMANCE
Properly designed and constructed Mound Systems that are operated according to guidelines
effectively treat septic tank effluent. Good performance is contingent upon siting, adapting
guidelines to specific site conditions, and care in construction (38, 66, 34, 105, 6).
Shallow Placement systems have not been evaluated to the extent that mound systems have.
Based on available data however, these systems perform well (105).
Little performance data exists for using Artificial Drainage in conjunction with on-site
wastewater disposal. Drainage systems associated with agriculture and foundations have performed
well in the past. Under proper site conditions, the adaptation of this technology to soil absorp-
tion systems should not be difficult (33). Plume recovery has not been demonstrated at a scale
appropriate to on-site systems.
DESIGN CONSIDERATIONS
Mounds should be located on a flat area or on the crest of a slope, and should be relatively
long and narrow with a maximum width of 10 feet. A minimum of 12 inches of sand, followed by at
least 9 inches of clean rock, should be placed on the roughened ground surface. Vegetative layers
should be broken up without smearing or compacting the soil to provide good contact between the
original soil and the mound materials. (The bottom area of the rock bed is based on an application
rate of 1.20 GPD/SF.) The distribution pipe, perforated with 3/16 to 1/4 inch holes, should then
be laid on the level rock with the holes down and covered with 2 more inches of rock. The rock bed
should be covered with 6 to 8 inches of straw or marsh hay (uncompacted) and red rosin paper to
prevent the cap and topsoil from filtering into the rock. Surface water should be diverted from
the mound and a grass cover should be established as soon as possible (48, 33).
I-A-26
-------
SOIL ABSORPTION SYSTEMS FOR HIGH GROUNDWATER OR SHALLOW SOILS FACT SHEET 2.4
October 1980
Design for Shallow Placement Systems should follow established criteria for conventional sub-
surface soil absorption except for depth and cover requirements. The depth requirement should be
established by site-specific criteria, with the main objective being the maintenance of 3 to 4 feet
of unsaturated soil for treatment above a limiting layer (rock or groundwater). The system should
be covered with 12 to 18 inches of loam soil backfill and a grass cover established (59, 33).
Curtain Drains are installed up slope from the soil absorption system and should be as deep as
possible while maintaining a gravity outfall to allow for groundwater mounding. Deeper drains
intercept more groundwater that may interfere with the treatment system. A horizontal distance of
10 feet between the artificial drains and the drainfield trenches should be maintained. Treatment
systems not requiring underdrains should be considered.
PLIABILITY
Mound Systems have proven to be reliable; the predominant problems are associated with the
pumps rather than the mounds themselves. Proper maintenance of pumps is therefore considered
essential for keeping the system reliable and the septic tank pumping (107).
Based on limited data, Shallow Placement Systems have been operating with little maintenance
and with a low failure rate (105).
Virtually no maintenance is required for Artificial Drains after installation. However, due
to the various types of groundwater drainage problems, no overall statement of the reliability of
all drainage systems can be made. The effectiveness of small plume recovery systems has not been
evaluated.
ENVIRONMENTAL IMPACT
Detrimental impacts include aesthetics due to size and shape (if not properly landscaped) and
possible drainage pattern alterations (94). Mounds allow development on some sites that might
otherwise not be suitable for on-site systems. Groundwater and public health impacts are similar
to conventional on-site systems.
For appropriate sites, the impacts of Shallow Placement Systems are similar to those of con-
ventional septic tank-soil absorption systems. Backfilling causes aesthetic problems along with
possible alterations of drainage patterns.
Curtain Drains result in surface water contamination if drains are too close to the soil-
absorption system. Vertical and underdrains cause groundwater contamination without adequate
separation distances between the drains and the soil absorption system. Plume recovery has the
potential to mitigate plant stimulation effects in lakes and streams by returning nutrients to
ground surface where they can be assimilated by yard vegetation. Odors and pathogens cause pro-
blems from recovered plumes if the system is not properly designed.
APPLICATION TO CLUSTER SYSTEMS
Mounds are not applicable to cluster systems because cluster systems require more suitable
soils than those required for mounds. For example, groundwater mounding would create a greater
problem in soils that require sand mounds than in more suitable soils.
Shallow Placement Systems can be designed for cluster systems as well as on-site treatment.
The distribution of effluent would fully utilize the soil absorption system if a pump and
pressurized network were used.
When designing cluster systems, the best available soils for wastewater disposal should be
used. Thus the use of artificial drainage would not be required. If, however, special circum-
stances warrant the use of artificial drainage, it could be used in conjunction with a cluster
system.
REFERENCES
104, 96, 39, 8, 32, 85, 38, 2, 66, 34, 24, 71, 49, 48, 59, 94, 105, 33, 6, 20, 106, 107.
I-A-27
-------
SOIL ABSORPTION SYSTEMS FOR HIGH GROUNDWATER OR SHALLOW SOILS
October 1980
FACT SHEET 2.4
DIAGRAM
MOUND SYSTEM
CROSS SECTION A-A'
PLAN VIEW
STRAW OR MARSH HAY AND LAYER
OF RED ROSIN PAPER
GRASS COVER
SAND FILL
SANDY LOAM SOIL
PERFORATED LATERAL
TOPSOIL
(49)
/
.PIPE FROM
PUMPING
CHAMBER
'ERFORATED
-LATERALS
5 BED
- AREA-
-DIKE
A1
(49)
SOIL TREATMENT UNIT USING SHALLOW
TRENCHES AND CURTAIN DRAIN
-DIVERSION FOR
SURFACE WATER
GRASS COVER
I -
*23&L^^^
'• '.,'.-. t.l ::•:';;. i,—0RAINFIELD—* ='".'• r'-^-'--'--4l'is;
. . • • ' V , ' . '• , \—rtDirciMAi
-AT LEAST 10'
0RAINFIELO-
TRENCHES
INTERCEPTOR OR CURTAIN DRAIN,.
, TO REMOVE EXCESS SOIL WATER
rT^r-r---^~~-iA^^^WATjRfABLE_i-; ;•'• \''
ORIGINAL
:, GROUND ,
SURFACE
(49)
UNDERDRAINS USED TO LOWER WATER TABLE
UNDERDRAINS
WATER
TABLE-x
\
1
1
1
1
[..*- *
.ABSORPTION-
TRENCHES
x:*v;.'
-^GRAVEL FILLED ABOVE
HIGH WATER TABLE
s^
DRAINAGE PIPE
^ •-
~~x
|
1
*-FILL
MATERIAL
^"' (71)
I-A-28
-------
SOIL ABSORPTION SYSTEMS FOR HIGH GROUNDWATER OR SHALLOW SOILS
October 1980
FACT SHEET 2.4
VERTICAL DRAIN TO INTERCEPT LATERALLY
MOVING PERCHED WATER CAUSED BY A
SHALLOW, THIN, IMPERMEABLE LAYER
PERCHED
WATER
TABLE
-VERTICAL DRAIN
FILL
MATERIAL I
GRAVEL FILL-'
ED ABOVE HIGH
WATER TABLEl
BACKFILL
PERMEABLE SOIL
.ABSORPTION BED.
(71)
ENERGY NOTES
Mound systems require a small dosing pump that uses about 50 to 250 KWH/yr as would a shallow
placement system that uses pressure distribution. Artificial drainage does not require energy if
the outlet can be directed to the surface through gravity. Plume recovery would require the most
energy because of the need for additional pumping.
COSTS
1980 Dollars; ENR Index = 3260
1) Mound Systems for individual home use, assuming a 3-bedroom house, range from $3,500 to
$6,500 for initial construction costs. A big variable is the haul distance required for the fill
material.
2) Shallow Placement Systems for a 3-bedroom house could be installed for $1,500 to $3,000
for a gravity-fed system.
3) Costs for installation of Artificial Drainage vary depending on depth required and the
local cost of gravel. For effluent plume recovery, the costs of an irrigation system installed on
a 1/4 acre lot with automatic controls range between $2,000 and $2,500. These figures do not
include construction of a shallow well and required pump.
OPERATION AND MAINTENANCE
Mound systems require the use of a small pump in addition to the periodic pumping of the
septic tank which costs between $35 and $75 annually.
Shallow placement gravity-fed systems cost the same for pumping (every 3-5 years) as do con-
ventional systems, or $15 to $25 per year.
Artificial drainage does not require any operational costs providing a pump is not used.
Estimated annual 0 & M costs for a plume recovery system are $100 for the irrigation system.
Additional costs for operation of a small pump would be added to this.
I-A-29
-------
SOIL ABSORPTION SYSTEMS FOR SLOWLY PERMEABLE SOILS FACT SHEET 2.5
October 1980
DESCRIPTION
Standard septic tank-soil absorption systems may not function adequately in slowly permeable
soils. Alternatives, described below, include oversized absorption areas, seepage pits, electro-
osmosis systems, mounds, and alternating drainfields.
1) Oversized Absorption Areas are constructed as are standard soil absorption systems except
that the size of the drainfield is larger than that recommended for systems on more permeable
soils. A larger area of slowly permeable soil is required to assimilate the effluent from a septic
tank that could be treated by less area in soils with a higher permeability.
2) Seepage Pits (Dry Wells) are deep excavations used to dispose of septic tank effluent.
Within the excavation, a porous walled chamber is installed and backfilled with clean rock. Septic
tank effluent enters the chamber and seeps out slowly into the crushed rock, and then into the soil
walls and bottom of the seepage pit.
3) Electro-Osmosis is an electric current passed through the soil to draw toward the cathode
the layer of water normally bound in fine soil pores. By burying dissimilar materials on opposite
sides of a drainfield, an electric potential develops in the soil water complex without the use of
an outside power source. The electric potential causes the positively charged water to be repelled
by the anodes and move to the cathodes located about 10 feet away from the absorption trench. The
wastewater is thereby filtered and tends to dissipate through downward seepage and evapotranspira-
tion (59, 71, 49).
4) Mounds are discussed in Fact Sheet 2.4, SOIL ABSORPTION SYSTEMS FOR HIGH GROUNDWATER OR
SHALLOW SOILS.
5) Alternating Drainfields are included in Fact Sheet 2.2, GRAVITY DISTRIBUTION FOR SOIL
ABSORPTION SYSTEMS.
COMMON MODIFICATIONS
1) Bec3use of the slow permeability of soils requiring Oversized Absorption Areas, dosing and
serial distribution should be considered along with alternating drainfields for use in combination
with an oversized system. Additional techniques that could be combined with oversized absorption
areas are pressure distribution, shallow placement, and trench liners. The use of trench liners
with a regular soil absorption system is also a possibility for certain soil conditions (See Fact
Sheet 2.6, SAND FILTERS).
2) Seepage Pits can be any size in diameter and depth providing they are structurally sound
and can be constructed without seriously damaging the soil (71).
3) Two absorption areas can be constructed with an Electro-Osmosis System and connected to
the septic tank while one field is in operation and the second is resting.
TECHNOLOGY STATUS
1) Oversized Absorption Areas and Seepage Pits are fully developed technologies.
2) Approximately 145 Electro-Osmosis Systems are currently operating in Minnesota with a
zero-failure rate. This success is due in part to the extensive monitoring done in the first year
of operation including eight inspections by the installers. (Personal communication with Frank
Coolbroth 9/30/80).
APPLICATIONS
Oversized absorption areas and electro-osmosis systems are suited to soils with a percolation
rate of 60 to 120 MPI. Electro-osmosis systems operate better in a soil mixture of clay and fine
sand rather than very dense clays. Seepage pits can be used to overcome slowly permeable layers
when suitable soils exist elsewhere in the soil profile. Percolation tests must be performed in
all the various layers. A weighted average is computed to size the sidewall area; however, soil
layers with percolation rates slower than 30 MPI are not included in the calculation.
I-A-30
-------
SOIL ABSORPTION SYSTEMS FOR SLOWLY PERMEABLE SOILS FACT SHEET 2.5
October 1980
LIMITATIONS
1) Oversized Systems are acceptable if the percolation rate is between 60 and 120 minutes per
inch. For a laboratory or field test of hydraulic conductivity, the acceptable range for an over-
sized system is up to 50% of the normal maximum for a given soil. Some regulations call for an
aerobic treatment unit to precede oversized soil absorption systems (46).
2) A minimum of three feet is typically required between the bottom of a seepage pit and the
water table or on impervious layer (49). Local codes should be checked before installing seepage
pits.
3) Electro-Osmosis systems are not intended for sites where the seepage trenches would pene-
trate groundwater. Due to the complicated soil, water, and electrical interdependence, adequate
tests must be performed in order to determine if the soil is suitable.
TYPICAL EQUIPMENT/NO. OF MFRS.
Oversized systems and seepage pits are locally available through septic tank installers.
Electro-osmosis systems are patented and must be installed by contractors who are licensed for such
work.
PERFORMANCE
1) In soils that have extremely slow permeabilities, Oversized Drainfields may not perform
well. Adequate performance is limited to soils that are borderline cases between acceptable and
unacceptable for conventional soil absorption systems. Performance may be improved on some sites
by pressure distribution, shallow placement, alternating drainfields, etc.
2) The performance of a limited number of sewage Electro-Osmosis Systems for on-site waste-
water treatment has been successful. The system has been used successfully for many years in the
construction industry for draining and stabilizing slowly permeable soils during excavation.
DESIGN CONSIDERATIONS
1) Typical design criteria for Oversized Drainfields are similar to criteria for systems in
suitable soils but are sized as follows: a) with permeability determined by a hydraulic conduc-
tivity test, the system is sized according to the determined liquid application rate based on a
waste flow of 150 gallons/bedroom/day, or b) when percolation tests are used, sizing is based on a
wastewater application rate of 0.2 gallons/square foot/day with a minimum of 750 square feet/
bedroom (24).
2) Seepage Pits must maintain a minimum of three feet from the bottom of the excavation to
the water table (or impervious layer) and the total excavation should not exceed ten feet. The
minimum diameter for seepage pits is five feet. Design is based on a weighted average percolation
rate which is used to size the infiltrative surface (or sidewall area of pit) (49, 71).
3) Because the Electro-Osmosis System is patented, the design, site testing, and construction
are performed by those licensed.
RELIABILITY
Both oversized drainfields and seepage pits are reliable if properly designed and constructed
on acceptable sites. Electro-osmosis however, has not been used with on-site disposal long enough
to establish any reliability record.
ENVIRONMENTAL IMPACTS
Subsurface disposal systems provide sufficient filtration, adsorption, and microbial degrada-
tion of harmful constituents in household effluent. System failures, however, can occur and are
related to site limitations or to improper installation, operation, or maintenance. Adverse envi-
ronmental effects attributed to failures of subsurface disposal systems generally involve the
contamination of ground or surface waters. This contamination then may result in public health
I-A-31
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SOIL ABSORPTION SYSTEMS FOR SLOWLY PERMEABLE SOILS
October 1980
FACT SHEET 2.5
hazards if drinking water is affected or in accelerated eutrophication if excessive amounts of
nutrients are delivered to lakes or streams.
Mitigation and avoidance of adverse environmental impacts depend on information regarding
site-specific conditions that led to system failures in a community, and the use of this informa-
tion to select repairs and replacement systems and to design new systems.
APPLICATION TO CLUSTER SYSTEMS
Of the three techniques discussed here, only oversized absorption fields have a possible use
for cluster systems. Soils for a cluster system should not be marginal because of the amount of
flow received. If the soil were basically satisfactory and an extra factor of safety were desired,
then an oversized absorption system would have a place in cluster systems. Seepage pits and
electro-osmosis systems are not appropriate for cluster systems.
REFERENCES
24, 49, 48, 59, 5, 76, 46, 71, 22, 72
DIAGRAM
SEEPAGE PIT (DRY WELL)
._4"lNSPECTION PIPE
^L „ • ,/T - r-
r|r>-r.
5 FEET
-MINIMUM-
DIAMETER
. WATER TABLE OR
"^IMPERVIOUS LAYER"
MANHOLE
MASONARY
LAID IN
RADIAL ARCH
AT LEAST 12"
. OF CLEAN ROCK'
3/4" TO 21/2"
' DIAMETER
T-AT LEAST 6"OF '
'ROCK ON BOTTOM
OF PIT
-'NOTE; TOTAL DEPTH OF EXCA-
VATION SHOULD NOT
EXCEED 10 FEET •. '
.
. AT LEAST
3.FEET .
(49)
I-A-32
-------
SOIL ABSORPTION SYSTEMS FOR SLOWLY PERMEABLE SOILS
October 1980
FACT SHEET 2.5
TYPICAL ELECTRO-OSMOSIS SYSTEM
ANODES
ANODES
— •>'-c/^e P ABSORPTION
TRENCH
THODE (-) ANODE (
•^
• DISTRIBUTION--
, PIPE.
COKE
MINER;
ROCI
ii>-'.
••.-.-.
XL —
<.
-VV;
M VENTS
PLAN VIEW
SECTION A-A'
(71)
ENERGY NOTES
Energy sources are not required for oversized systems and seepage pits unless pressure distri-
bution or an elevation difference between the septic tank and soil absorption systems requires the
use of a pump. Electro-osmosis applied to on-site wastewater treatment requires that an electro-
motive potential be developed, but this potential can be established without the addition of energy
by using the proper materials for constructing the anodes and cathodes.
COSTS
1980 dollars; ENR Index = 3260.
1) The following table compares the typical costs of an oversized drainfield system to a
conventionally sized system for a 3-bedroom house with an assumed drainfield size.
SYSTEM
Conventional
Oversized
COST OF COST PER FT2
INSTALLED SEPTIC OF DRAINFIELD
TANK ($) ($/FT2)
SIZE OF DRAIN- COST OF DRAIN- TOTAL SYSTEM
FIELD (FT2) FIELD ($) COST ($)
350-750
350-750
1.00-2.50
1.00-2.50
1000
1250
1000-2500
1250-3125
1350-3250
1600-3875
2) Seepage Pit Systems constructed for a 3-bedroom house would cost $1,000 to $1,500.
3) Electro-Osmosis Systems have construction costs in the $5,000 to $6,500 range assuming a
3-bedroom house.
OPERATION AND MAINTENANCE
Operation costs for all three systems relate only to the required septic tank pumping. These
costs range from $15 to $25 per year depending on the local pumping costs and the frequency with
which the septic tanks are pumped.
I-A-33
-------
SAND FILTERS FACT SHEET 2.6
October 1980
DESCRIPTION
Filtration is a process that has been used for many years to treat water and wastewater. The
process involves passing the liquid to be treated over a bed of sand that is 24 to 40 inches deep
and is supported by a gravel layer and is underdrained. The effluent from the sand bed is then
disinfected (as required) and either discharged to surface waters or applied directly to a sub-
surface soil absorption system. A septic tank or some other form of solids separation is required
for pretreatment prior to filtration. Filters are dosed intermittently and allowed to dry between
applications. Mechanisms of purification include physical straining, chemical sorption, and
biological decomposition.
COMMON MODIFICATIONS
The three basic variations of sand filters for on-site and small scale applications are 1)
buried filters, 2) intermittent filters, and 3) recirculating sand filters. Buried filters are
constructed underground are usually sized more conservatively than other filters, and are more
easily accessible. Buried sand filters are constructed with walls to hold the units together or
by using the pitwalls to contain the media. Recirculating filters are designed using a higher
application rate and subsequently require less area than buried and intermittent filters. Recir-
culating filters have a chamber which mixes the septic tank (or other treatment process) effluent
with the collected effluent from the filters, and then pumps the combination back over the filter.
A variation of the buried sand filter is lining trenches or beds with sand prior to the con-
struction of a conventional soil absorption system. The effluent then flows through the sand
directly into the soil instead of being collected by underdrains. Sand-lined beds and trenches can
be used on sites with very well drained soils (with a percolation rate less than 6 MPI), or where
the depth to an excessively permeable layer (e.g. rock fragments) is less than four feet from the
surface. This disposal method is not allowed in floodplains or where soil mottling (or ground-
water) appears at less than four feet below the bottom of the aggregate (108).
TECHNOLOGY STATUS
Filtration is a developed technology that is well suited to on-site applications. Although
recirculating sand filters have been in use only since the late 1960's, they are also well
developed technologically.
APPLICATIONS
Filtration is one treatment method that is advantageous for on-site disposal when the effluent
required is of higher quality than that of septic tank effluent, such as when stream discharge is
necessary because of site limitations. Some site conditions allow subsurface disposal only if a
high degree of treatment precedes the disposal. This may result from high groundwater or from a
creviced limestone layer that would not be acceptable for conventional soil absorption systems
alone. Buried filters are applicable to flows from individual homes. Intermittent sand filters
can be used for individual home application if shallow bedrock or high groundwater preclude the use
of a buried system. Recirculating sand filters are intended to give off less odors than inter-
mittent filters because the applied sewage is a mixture of septic tank effluent and filter effluent
(37). Recirculating filters would therefore be applicable when odors could be a problem.
LIMITATIONS
The size of open sand filters is limited by land availability and, generally, the design flow
is limited to 0.25 MGD. Odors may be a problem if septic tank effluent is applied directly to open
sand filters. Application of effluent from an aerobic treatment process will reduce odors, extend
filter runs, and produce a higher quality effluent than wastewater pretreated with septic tanks.
Local availability of sand may restrict the use of filtration in some areas. Intermittent open
sand filters may require an insulated cover in areas of prolonged freezing, which would also help
control odors.
Buried sand filters have the problem of accessability if clogging should occur. Two buried
filters could be used in an alternating system to prolong filter life, by allowing a resting cycle
for each. Buried sand filters are normally used for very small flow applications, such as indi-
vidual residences.
I-A-34
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SAKD FILTERS
October 1980
FACT SHEET 2.6
TYPICAL EQUIPMENT/NO. OF MANUFACTURERS
Sand filters consist of distribution piping, sand, gravel, and underdrain piping, all of which
are locally supplied.
PERFORMANCE
Sand filtration produces a high quality effluent with BOD_ values usually less than 10 mg/1.
Concentrations of suspended solids are usually less than 15 mg/1. Although nitrification is almost
complete, the total nitrogen present is essentially unchanged. After maturation, sand filters
remove only small amounts of phosphorus. Performance levels decrease with a reduction in ambient
air temperature (96, 71).
DESIGN CONSIDERATIONS (71)
Pretreatment:
Hydraulic Loading:
Media:
Minimum of Sedimentation (usually a septic tank)
<1 GPD/SF (buried)
2-5 GPD/SF (intermittent)
3-5 GPD/SF (Recalculating based on forward flow)
Washed Durable Granular Material Less Than 1% Organic Matter by Weight
Underdrains:
Distribution for
Buried Filters:
Distribution for
Intermittent &
Recirculating:
Dosing:
Effective size: 0.50 - 1.0 mm (buried)
0.35 - 1.0 mm (intermittent)
0.30 - 1.5 mm (recirculating)
Uniformity coefficient: <4.0 (<3.5 preferable)
Depth: 24-36 inches
Material: Open joint or perforated pipe
Slope: 0.5 - 1 percent
Bedding: Washed durable gravel or stone (1/4 to 1 1/2 inches)
Venting: Upstream end
Material: Open joint or perforated pipe
Bedding: Washed durable gravel or stone (3/4 to 2 1/2 inches)
Venting: Downstream end
Troughs on surface, splash plates at center or corners, or sprinklers
Flood filter to ^ 2 inches
Frequency: Greater than two times daily (buried and intermittent)
Pump 5-10 min. per 30 min.; empty recirculation tank in less than 20 min.
(recirculating)
Recirculation Chamber: Volume equivalent to at least one day's raw wastewater flow.
For sand-lined trenches or beds, standard soil absorption system design criteria must be
followed in addition to placing a layer of sand under the gravel aggregate.
RELIABILITY
Sand filters are quite reliable although they require a little more attention than septic tank
soil absorption systems.
I-A-35
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SAND FILTERS
October 1980
FACT SHEET 2.6
ENVIRONMENTAL IMPACT
After a sand filter treats the septic tank effluent, disposal is still a problem. Local codes
should be consulted for any planned discharging system. Odors are yet another problem for inter-
mittent sand filters receiving septic tank effluent, although covers can be installed as a mitiga-
tive measure.
APPLICATION TO CLUSTER SYSTEMS
Open sand filters are easily adaptable to multi-family units with design flows of less than
0.25 MGD. Multiple filters as opposed to single filters are suggested for larger systems. General
design criteria for individual filters can be followed, but special emphasis must be given to
distribution of effluent. Buried sand filters are not recommended for cluster systems.
REFERENCES
96, 71, 14, 86, 32, 8, 94, 67, 44, 108, 49, 37, 9, 36.
CHEMICALS REQUIRED
Local requirements for disinfection should be considered for discharging systems. These
requirements may include the use of chlorine or iodine.
RESIDUALS GENERATED
In addition to the usual periodic pumping of septic tank solids, sand that is scraped off of
the top of the filter must also be disposed of in an acceptable manner. Disposal can be by on-site
burial or land filling at an approved site.
DIAGRAM
LINER SYSTEM FOR PROBLEM SOILS
4 INCHES OF MAYOR STRAW AND
ALAYER OF RED ROSIN PAPER
nUbIN KAHtH\ —-^ 1 IU b
\^ *^--. FOR SI
.. ". ........,-V,,.... n ...,. , .,_,,.I7.7.»
MOUND BACKFILL
4TO6 INCHES
SETTLEMENT
• 4 INCH ' ' ..^EWSST;
DISTRIBUTION-
I.? I nluu I ivn , VI.- \ "S- ->,- • -t^^ff '
,'.PIPE "--.', '-. ,\j:.v ;>•'•'• •j--'.:V>*TV-":
:.CLEAN HOCK-^-^ .-X-'-'^^-W"'7?'-
. 3/4"T02l/2"-,,y,' ^ ^SGSJL jLilL^
.'. DIAMETER ~;\.':' *'? ^ ' '"* "" ^
FILL SOIL
, NOTE: FILL SOIL SHOULD
, ' • BE SANDY LOAM
,•'-•' 'WHEN ORIGINAL
,. • ' ''SOIL IS SAND
v, ; . 3 FEET TO GROUNDWATER
-\;'' OK OTHER BARRIER LAYER ,
'."FILL SHOULD BE
• SAND WHEN ORIG-
' .1INAL SOIL IS CLAY
(49)
BURIED INTERMITTENT FILTER
DRAINAGE
PERFORATED OR
FILTER MEDIA OPEN JOINT
DISTRIBUTORS
^PERFORATED OR V£.
-.'.OPEN JOINT PIPE,
.. ' TARPAPER OVER ;
•OPEN JOINTS
(71)
RECIRCULATING SAND FILTER SYSTEM
PRELIMINARY
TREATMENT UNIT
RAW
WASTE
TO DISC
i
' .FLOAT
/VALVE '
LRT- —
(
T ^
n
FREE ACCESS
SAND FILTER
RECIRCULATION
TANK
PUMP
(71)
I-A-36
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SAND FILTERS
October 1980
FACT SHEET 2.6
FREE ACCESS FILTER
^-INSULATED COVER^
DISCHARGE
•^DISTRIBUTION PIPE |
1 R VENTvfx IM T
-I SPLASH PIPE X-lV1 L
Dl ATC^. LJ >, >, UJ
'• '•'•'.:'MEDIA': r':.''°'.~
PEA GRAVEL
CONOR TE
SLAB
^-COLLECTION ,
PIPE
.GRADED
GRAVEL
1/4 TO 11/2
PERFORATED OR—y , . ' '
OPEN JOINT : •
(71)
ENERGY NOTES
The only power requirement is for the distribution system employed. Depending on the type of
distribution system, power requirements will vary but should be less than 0.1 KWH/DAY. Recir-
culating may increase power by 50 to 250 KWH/yr.
COSTS
1980 dollars; ENR Index = 3260. The construction costs given below are for a complete system
for a 3-bedroom house. These costs include the septic tank and associated piping, the sand filter
along with underdrains, and all associated labor. Disinfection is not included.
Buried sand filters:
Intermittent sand filters
Recirculating sand filters
$2,000 to $4,000
$2,500 to $4,500
$2,000 to $4,000
The local availability of sand is a major variable in determining the system costs.
OPERATION AND MAINTENANCE
Pump items to be considered in operating a sand filter include the following:
Septic tank pumping
Pump operation and maintenance for recirculating and dosed filters
Restoration of filter capacity for recirculating and intermittent filters
Checking the filter surface periodically
The following are annual 0 & M costs for a typical system installed for a three-bedroom house:
Buried sand filters:
Intermittent sand filters:
Recirculating sand filters:
$ 15 - $ 25
$150 - $250
$ 70 - $100
I-A-37
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LAGOONS FACT SHEET 2.7
October 1980
DESCRIPTION
Wastewater treatment lagoons or stabilization ponds are artificially created bodies of water
that retain wastewater until natural biological processes reduce pollutant concentrations to an
acceptable level. The treatment process is preferred by many small municipalities because of the
low maintenance requirements. The three basic types of lagoons are aerobic, (often employing
mechanical aeration), faculative, and anaerobic. For on-site use, facultative lagoons are the most
widely used.
COMMON MODIFICATIONS
In addition to using lagoons as a treatment and discharge process, they are used as an evapo-
ration and/ or infiltration system with no discharge. Controlled discharges, the releasing of
wastewater to coincide with optimum stream characteristics, are another possibility. The size of
the lagoon needs to be altered to accommodate the increased storage associated with a controlled
discharge. Lagoons are often divided into cells for better performance.
TECHNOLOGY STATUS
The technology for lagoons is fully developed; however, the application to individual homes
has not received much attention in the literature.
APPLICATIONS
Lagoons can be used for on-site treatment when subsurface disposal is not possible. Evapora-
tive lagoons are useful in arid regions, and infiltrative lagoons are useful only where groundwater
contamination is not a concern or is shown to be acceptable. Most lagoons require a substantial
land area and liners may be necessary for certain applications.
LIMITATIONS
During times of high evaporation, lagoons may not maintain the depth required for proper
operation without the addition of water. Low liquid levels might cause unwanted plant growth
within the pond area. In cold climates an ice cover may reduce the treatment efficiency and
possibly cause odors while thawing. Minimum distances to property lines and residences limit the
use of lagoons to sites with sufficient area for buffers.
TYPICAL EQUIPMENT/NO. OF MFRS.
Lining systems/6 Pipe and excavation is locally supplied.
PERFORMANCE
Performance of facultative lagoons varies with climatic changes. Algae production during warm
weather contributes to high suspended solids levels. Reduced biological activity due to low tem-
peratures results in higher BOD values. Removal rates for BOD_ usually range from 75 to 90 percent
and effluent SS values of 20 to 150 mg/1 are typical. Phosphorus and nitrogen removals are usually
less than 50%.
DESIGN CONSIDERATIONS
Typical design standards include minimum separation distances of 50 feet from property lines
as measured from the adjoining shoreline, 200 feet from the nearest residence, and 50 feet from a
potable water supply, a stream, lake, or other water body. Standards call for 440 square feet of
lagoon surface per bedroom with a minimum of 1,500 square feet. The hydraulic retention time
should be at least 60 days. Longer times should be used when severe winters preclude discharge or
for controlled discharges. The minimum freeboard should be 2 feet with an operating depth of 3 to
5 feet (32). Organic loading for winter conditions as well as for summer is typically 10
Ibs/acre/day. The range is 15-65 Ibs/acre/day (45).
I-A-38
-------
LAGOONS
October 1980
FACT SHEET 2.7
RELIABILITY
Particularly for use with domestic wastes, lagoons are very reliable as they will continue to
operate with little or no operator assistance.
ENVIRONMENTAL IMPACT
The environmental impact of lagoons is limited to possible odors during mixing caused by wind
and/or seasonal temperature changes and seepage into permeable soils. Proper siting and/or lining
can circumvent these impacts.
APPLICATION TO CLUSTER SYSTEMS
Lagoons are a candidate for multi-home or cluster system use where variable suspended solids
and BOD are acceptable in the effluent. Low operation and maintenance along with low construction
costs are major advantages for these systems.
REFERENCES
94, 51, 32, 29, 82, 92, 88, 45, 68.
DIAGRAM
FACULTATIVE LAGOON
INTERMEDIATE
(FACULTATIVE)
INLET (TYPICALLY
NEAR 1/3 POINT) '.
1 EFFLUENT DISCHARGE SUMP WITH
MULTIPLE DRAWOFF LEVEL DISCHARGE
CAPABILITY (TO MINIMIZE ALGAE CON-
L CENTRATIONS IN DISCHARGE)
I—TRANSFER PIPE TO SECONDARY
]• CELL, LAND APPLICATION
•L OR CHLORINATION AND DISCHARGE
LINER (IF NECESSARY) '
SLUDGE STORAGE ZONE (FOR PRIMARY CELLS ONLY
WITHOUT PRIOR PRIMARY SEDIMENTATION)
-1 '
' ' •' ' ' (94)
ENERGY NOTES
Lagoons do not use any energy unless a) mechanical aerators are used, b) an elevation dif-
ference requires pumping to the lagoon, or c) constant feed chlorinators or ultraviolet lights are
used for disinfection.
I-A-39
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LAGOONS
October 1980
FACT SHEET 2.7
COSTS
Costs are highly dependent on local excavation costs.
the following:
Other costs to be considered include
1) Excavation
2) Final Grading
3) Seeding
4) Fencing
5) Piping
6) Access Road (if necessary)
7) Land
8) Inlet and Outlet Structures
9) Disinfection (if necessary)
10) Liners
For a community of 100 people, the initial cost for a stabilization lagoon is approximately $404.00
per person. For a community of 200 people, these initial costs are approximately $267 per person.
Operation and maintenance costs for a 100 and 200 person community are $6.00 per person and $4.30
per person respectively (88).
OPERATION AND MAINTENANCE
Operation and maintenance consists of mowing the grass around the lagoon, adding water when
necessary to maintain adequate bacterial activity and prevent mosquito breeding, and taking and
analyzing samples when necessary to comply with surface discharge requirements.
I-A-40
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FIXED FILM TREATMENT FACT SHEET 2.8
October 1980
DESCRIPTION
These biological treatment processes operate by allowing wastewater to contact a media of
large surface area. Microorganisms attach to the media and metabolize the pollutants in the waste-
water. The process usually works aerobically with air introduced either mechanically (e.g.,
diffusers) or by natural ventilation. There are many variations of this process, the two most
common being: 1) rotating biological contactors, and 2) the trickling filter or packed tower.
Rotating Biological Contactors (RBCs) - are rotating discs usually made of polyethylene or
styrofoam that are mounted on a horizontal shaft. The discs are partially submerged in the waste-
water (about 40%) and as they rotate, aerobic microorganisms attach, subsequently treating the
wastewater.
Trickling Filters - or packed towers, consist of a tank filled with rock, synthetic, or red-
wood media. The wastewater is distributed over the media where the fixed film of microorganisms
acts in much the same way as the film on the RBCs. Aeration can be provided by natural ventilation
or by diffusers.
A Submerged Media System - is a variation of the trickling filter in which the media is com-
pletely submerged in wastewater; the system can be aerobic or anaerobic (and upflow or downflow).
COMMON MODIFICATIONS
Fixed film processes such as RBC's can be used in series for additional treatment or in con-
junction with other treatment processes, such as clarification and filtration to provide effluent
acceptable for discharge. Recycling is another common modification as is adding air to the tanks
(94).
TECHNOLOGY STATUS
Trickling filters have been in widespread use for municipal wastewater treatment plants for
nearly 50 years. RBCs have been used in the U.S. since 1969. The application of fixed film reac-
tors to on-site systems, however, is relatively new.
APPLICATIONS
Fixed film reactors are used (usually with disinfection) in applications where the effluent is
discharged into surface waters. These units can be used for flows from individual houses and, by
increasing the size or number of units, for larger systems such as multi-family and municipal
installations.
LIMITATIONS
Trickling filters are temperature sensitive and therefore need to be insulated against cold
weather. RBCs must be covered to prevent excessive algal growth from building up on the discs. For
on-site applications, consideration must be given to pretreatment and ultimate disposal of waste-
water. Pretreatment can usually be accomplished with a septic tank, while wastewater flowing from
the fixed film reactor must undergo a solids separation process and disinfection prior to stream
discharge.
TYPICAL EQUIPMENT/NO. OF MFRS.
Rotating Disc Systems/3 (only 1 is currently marketed in North America).
PERFORMANCE
Very little information exists for individual fixed film systems. Reported BOD and SS re-
moval rates are 75 to 95% depending on the particular process. The effluent is normally nitrified
for aerobic processes while little phosphorus reduction takes place. Indicator organisms are
normally reduced by 90-99 percent (8).
I-A-41
-------
FIXED FILM TREATMENT
October 1980
FACT SHEET 2.8
DESIGN CONSIDERATIONS
A sedimentation pretreatment process is required and can usually be accomplished by using a
septic tank. Hydraulic loading varies between 25 and 100 gpd/ft2 for upflow/downflow filters and
between 0.75 to 1.0 gpd/ft2 for RBC units. Although recycling is often thought to complicate the
on-site system, hydraulic load calculations must include recycled flow as well as forward flow to
the filters (71).
Organic loading can be considered from 5 to 20 Ibs. BOD /1000 ft3 for upflow/downflow filters
and from 1 to 1.5 Ibs BOD^/1000 ft3 for RBCs. Again, any loading from recycling is added to the
loading from the forward flow to compute the entire organic loading (71). Final settling after the
fixed film treatment is required. Disinfection is usually required for stream discharge and can be
added after final clarification.
RELIABILITY
Biological fixed film systems are not usually as labor intensive as extended aeration systems
but do require more attention than conventional ST-SAS. Because of their mechanical nature and
dependence on electricity, these systems are less reliable than gravity-fed soil dependent systems.
ENVIRONMENTAL IMPACT
Odor impacts are possible if waste should turn septic or if electrical service is interrupted
for an extended time period. Permits must usually be obtained for surface water discharges.
APPLICATION TO CLUSTER SYSTEMS
These systems are conducive to cluster systems because they can handle wastewater from several
residences without much more operation and maintenance than that required for individual systems.
REFERENCES
59, 24, 71, 70, 92, 94, 8, 102, 103, 15, 30.
RESIDUALS GENERATED
During the treatment process, the biological buildup on the media becomes too thick and the
forces from the applied wastewater slough off the biomass. A new layer of growth begins; however,
the solids sloughed off must be removed periodically from the reactor to prevent denitrification
and rising sludge. These extra solids are normally wasted to the septic tank which may result in
increasing the septage pumping interval to 1.5 to 2 year cycles (8, 71).
DIAGRAM
PRIMARY TANK-
SLUDGE STORAGE
ROTATING BIOLOGICAL CONTACTOR
.ROTATING DISCS
INFLUENT
DRIVE
OUTLET
FINAL SETTLING
SLUDGE STORAGE
FINAL
OUTLET
CHLORINE CHAMBER
(OPTIONAL)
(15)
I-A-42
-------
FIXED FILM TREATMENT
October 1980
FACT SHEET 2.8
TRICKLING FILTER
UNFLUENT
DISTRIBUTOR
- ' •'• o . -Vy f.-i -•"..'to*
'lj NDER ~DR At N "v-"•?'
_FIXED
MEDIA
TO CLARIFIER O
SEPTIC TANK
(71)
SUBMERGED
MEDIA
WASTE
(71)
ENERGY NOTES
Depending on the process used, power requirements vary but usually range from 1 to 4 KWH/day.
Additionally, an increase in septage pumping requires more energy. Although very limited data is
available, operation and maintenance requirements of 8 to 12 person hours per year plus analytical
services are required to ensure proper performance (71, 8).
COSTS
1980 dollar; ENR Index = 3260. Capital costs for a fixed film reactor for a typical individual
3-bedroom home application range between $1,750 and $3,000. 0 & M costs from $45 to $70 per year
for power and septic tank pumping can be expected.
I-A-43
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HOLDING TANKS FACT SHEET 2.9
October 1980
DESCRIPTION
Holding tanks, which are waterproof containers that hold wastewater, provide no treatment
except for some anaerobic digestion of settled solids. The wastewater must be removed from the
tanks at intervals depending on size of tank.
COMMON MODIFICATIONS
Holding tanks can be used in conjunction with on-site soil absorption systems to accept waste-
water when the soil absorption system cannot handle all the load due to high use or a seasonally
high watertable.
TECHNOLOGY STATUS
Holding tanks of concrete, fiberglass, steel and cross-linked polyethylene are fully developed
and commercially available. Tanks designed to be septic tanks are normally used since they are
locally available. Tanks with hopper bottoms and built-in riser pipes with quick-connect fittings
above ground avoid the disruption and spillage problems of common holding tanks. Probably because
of low demand, such special purpose tanks are in common use.
APPLICATIONS
Individual buildings for which no on-site treatment options are available and for which off-
site technologies are not economically competitive, holding tanks are viable options. By accepting
toilet waste only, holding tanks reduce the nutrient load to on-site treatment systems in areas
where groundwater or surface water pollution is possible.
LIMITATIONS
Holding tanks are considered temporary measures where on-site disposal problems exist but
could also be considered permanent systems for summer or other short-term or low intensity uses.
Permanent year-round applications are infrequent because pumping costs are high and management
mechanisms are not available to ensure proper frequency of pumping and disposal of wastewater (32).
TYPICAL EQUIPMENT/NO. OF MFRS.
Locally supplied/Many mfrs. available.
PERFORMANCE
Concrete and cinder block holding tanks are not water-tight unless lined or epoxy coated.
Fiberglass or cross-linked polyethylene tanks provide a more water-tight tank that is easier to
clean when pumped out. These tanks are also durable and have a long service life.
DESIGN CONSIDERATIONS
In designing a system of holding tanks, one of the prime considerations is the disposal of the
wastes after pumping. Because the tanks provide little or no treatment and the waste is in an
anoxic state, special treatment provisions must be made. This type of waste could upset the bio-
logical balance of small wastewater treatment plants. Other considerations are the size of the
proposed tanks based on the frequency of pumping desired, expected flows, and capacity of hauling
vehicle. A meter should be installed with holding tanks to indicate the remaining capacity. High
water alarms should also be a part of all holding tank installations. Holding tanks should be
accessible in all types of weather for pumping trucks and risers with quick-connect fittings should
allow for easier access when pumping. During construction in high groundwater areas, holding tanks
should be anchored securely to avoid "floating up" of a partially full tank.
RELIABILITY
With a proper management system, including regular pumping, holding tanks are reliable. A
meter, indicating capacity remaining in the holding tank, increases the reliability as does a high
water alarm.
I-A-44
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HOLDING TANKS
October 1980
FACT SHEET 2.9
ENVIRONMENTAL IMPACT
The high cost of pumping holding tanks may offer an incentive for illegal disposal. Upsets of
wastewater treatment plants receiving holding tank wastes may result in decreased water quality in
the receiving stream.
REFERENCES
76, 32, 85, 49.
DIAGRAM
HOLDING TANK
,PIPE FOR ACCESS
TO INLET
CLEANOUT-
PIPE WfTH
TIGHT CAP
-MANHOLE
WATER FLOWING INTO SEWAGE
SYSTEM SHOULD BE METERED
(49)
ENERGY NOTES
These systems are energy intensive from the standpoint of the requirement for pumping. After
pumping and hauling, the waste must still undergo treatment which requires additional energy input.
COSTS
1980 dollars; ENR Index = 3260. Installing a holding tank is similar to installing a septic
tank without the drainfield. Costs for a 1,000-gallon septic tank range from $350 to $750 for the
total system installation including anchoring and alarm systems.
OPERATION AND MAINTENANCE
Annual pumping costs depend on the size of the tank and the daily flow rate. For example, a
family of 3 producing 50 gpcd with a 1,000-gallon holding tank would require pumping every 7 days.
Assuming a $40 charge per pump out, annual costs would exceed $2,000. If an air assisted toilet
(see FACT SHEET 1.4) using 0.5 gallons per flush were to be discharged into a 1,000-gallon holding
tank with separate greywater treatment provided, pumping would be required only 3 times per year.
The annual costs for pumping would therefore be reduced to $120, which would not include any costs
associated with greywater disposal.
I-A-45
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SEPTAGE DISPOSAL BY LAND APPLICATION FACT SHEET 3.1
October 1980
DESCRIPTION
Application of septage to the land is by far the most commonly used means of septage disposal.
Of the total septage generated, it is estimated that 60 to 90% of the total is disposed on land.
Septage disposal on land includes surface application, sub-surface application, sanitary landfills,
and disposal trenches. Septage pumped from septic tanks is directly disposed on land or treated
prior to land disposal.
Surface application of septage is quite common in remote areas where human contact is minimal
and land is readily available. Septage is spread over grassed areas or plowed soil by a pumping
truck, by special spreading vehicles, or by a farm tank wagon usually pulled by a farm tractor.
The use of separate collection and spreading vehicles depends on the size of the operation and the
condition of the spreading site. Land spreading can also be achieved by ridge and furrow, and
spray irrigation methods. However, the use of these methods with septage has not been reported.
Land spreading in most areas cannot be practiced year-round. In colder climates, land appli-
cation should be limited to unfrozen surfaces to prevent runoff during thaws. During wet periods
the saturated soils generally restrict field access by disposal equipment and increase runoff of
contaminated water. Thus, to allow year-round operation of septage collection and disposal,
septage storage facilities generally are included with land spreading. Storage facilities also
allow monitoring of septage characteristics before its application on land.
Subsurface application of septage is usually accomplished by one of the following methods.
o Plow-Furrow-Cover (PFC) - septage is applied to the plowed furrow 6 to 8 inches below the
original surface and is immediately covered by a following plow.
o Sub-Sod-Injection (SSI) - septage is injected into openings made in the ground below a sod cover
crop. The septage is injected in a wide band or several narrow bands 6 to 8 inches beneath the
sod surface.
o Terreator - is a patented device which injects septage below the surface of the ground into a
3-3/4 inch diameter mole-type hole made by an oscillating chisel point device.
Subsurface application offers better odor and pest control than surface spreading and reduces the
likelihood of people, pets, and pests coming into contact with septage. Immediate incorporation of
septage in soil, however, minimizes nitrogen volatilization, thereby increasing nitrogen loading in
the soil. While this is desirable for fertilization purposes, it is not desirable for minimizing
accumulation of nitrates in groundwater.
In a sanitary landfill septage disposal is mixed with solid waste and covered with soil.
Landfilling municipal sewage sludge is used extensively and is limited to dewatered sludge to
minimize water drainage and leaching. While septage disposal in a sanitary landfill is practiced
in some states, many landfill operators are reluctant to accept septage because of potential
leachate problems.
Land application of septage is sometimes accomplished in disposal trenches. A series of
trenches is dug, and small amounts of septage are pumped into the trenches in lifts and allowed to
dry out. When the trenches are full, they are either covered and abandoned, or dewatered solids
are removed and disposed of in a landfill.
TECHNOLOGY STATUS
Surface application is fully developed technologically. Studies at the University of
Connecticut (89) demonstrate the feasibility of soil injection as an acceptable method for
subsurface application of septage.
A survey of sanitary landfill operators indicates that approximately one-third of the land-
fills surveyed accept both sewage and septage disposal (91). However, septage is rated 5 and
sewage sludge 2 (median values) on a 0-10 scale of increasing potential hazard. A few states have
laws completely restricting the disposal of septage in landfills. Others do not recommend land-
filling because moisture control is too difficult to maintain (7).
I-A-46
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SEPTAGE DISPOSAL BY LAND APPLICATION FACT SHEET 3.1
October 1980
Trench disposal is a common technique for handling septage in rural areas, however, in many
cases this method is considered a temporary solution (7).
APPLICATIONS
Surface application of septage is considered a disposal and utilization method. Since septage
can be considered a form of fertilizer because of its nutrient value, it can be applied at sites
designated solely for disposal purposes or on agricultural land. If the land is to be put into
crop production, an intermediate period of grass cover for at least one year is desirable. Septage
can be applied on land directly after pumping it out of septic tanks or after stabilization.
Septage that has not been stabilized should not be spread on crops in the same growing season they
will be grazed on or harvested for domestic livestock. Additionally, septage should not be applied
to land that is to be immediately used for growing crops for human consumption.
Subsurface application is used when odor and pest control requirements prevent the use of
surface application. The proximity of the disposal site to inhabited areas may dictate the control
measures
Septage pumped out of septic tanks could be disposed of in a sanitary landfill provided that
the ratio of liquid (septage) to solid waste is such that low moisture content of the mixture is
achieved prior to burial. Dewatered septage could also be disposed in a landfill.
Trench disposal is used to dispose of raw septage and requires less land than other land
application methods.
LIMITATIONS
Surface application rates are limited by nitrogen and trace metal contents of the septage.
Nitrogen application in excess of crop requirements could leach downward through soil and con-
taminate groundwater. Land with slopes greater than 8% and low lying fields are not suitable for
septage application.
Subsurface application rates are also limited by nitrogen and trace metals. Soil incorpora-
tion equipment does not operate well on frozen ground. Application when the ground is saturated
or snow-covered also is not acceptable.
Landfills are generally not acceptable for septage disposal in areas where rainfall exceeds 35
inches/year. For septage disposal to be acceptable in such areas, leachate control facilities must
be present in natural form or constructed.
Sites for trench disposal may have limited lifetime due to groundwater contamination or ex-
haustion of available land at the site.
TYPICAL EQUIPMENT
Surface application and sanitary landfills: The most common equipment is the septage pumper
truck which combines the pumping/hauling and spreading operations. The spreading operation can be
made more effective by fitting a splash plate to the truck discharge line which would increase the
area of application. For periods of wet weather, a truck can be equipped with flotation tires to
prevent slippage. For a large centralized disposal area with septage holding facilities, a tank
wagon pulled by a tractor can be used.
Subsurface application: The PFC technique involves a 16-inch single bottom mold-board plow, a
furrow wheel, and a 16-inch coulter. The SSI device consists of two plows assembled together to
provide a 24-inch-wide opening, 6 to 8 inches below the surface. The Terreator is patented equip-
ment that uses an oscillating chisel point device to make 3-3/4 inch diameter mole-type holes (99).
The incorporation of septage can be achieved by using a farm tractor and tank trailer with
attached subsurface equipment, by using commercially available tank trucks with subsurface injec-
tion equipment, or by using tractor-mounted subsurface injection equipment in conjunction with a
central holding facility and flexible "umbilical cord" (7). A year-round operation also will
require holding facilities to store the septage during inclement weather.
I-A-47
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SEPTAGE DISPOSAL BY LAND APPLICATION FACT SHEET 3.1
October 1980
Diposal trenches: Backhoe and hauling tank truck.
PERFORMANCE
Surface application of septage is considered a zero discharge, resource recovery system.
Septage acts as a soil conditioner and as a fertilizer. However, improper management leads to
problems such as contamination of the groundwater, heavy metal accumulation in the soil, and sur-
face water pollution. A three-year study to evaluate the effects of land spreading of domestic
septage on groundwater nitrate concentrations and microbial penetration concluded that no signi-
ficant increase in well water nitrates was observed and no evidence of fecal coliform penetration
was found (4). The septage application rate was from 36,000 gallons to 198,000 gallons per year
per acre applied intermittently. The equivalent nitrogen loading of the septage was 50 and 200
pounds of nitrogen per acre per year. The soil on the application site was sand with a sand to
loamy sand surface layer with high permeability, and thus, represented maximum potential for pollu-
tion of the groundwater.
Studies at the University of Connecticut (89) have found that the PFC method is preferable to
the Terreator and SSI for subsurface application. With the SSI method, a sod cover is required and
the frequency of equipment access to the field site is less because of field techniques used. The
Terreator is still in developmental stages, and corrective work will be required before it can be
evaluated.
DESIGN CONSIDERATIONS
The principal design factors for surface application are application rate, soil conditions,
site location, and climate. Application rates determine the area needed for the volume of waste to
be handled. Application rates for septage can be based on nitrogen loading or on heavy metal
loading. For domestic septage, application rates based on nitrogen loading appear to be more
restrictive than rates based on heavy metal loading (23) . The application rates recommended by the
University of Maine Life Science and Agricultural Experiment Station vary from 62,500 gal/acre/year
for well drained soil to 37,000 gal/acre/year for moderately well drained soils. These application
rates would result in nitrogen loading of about 500 Ib N/acre/year in well drained soil and 300 Ib
N/acre/year in moderately well drained soil (23). These nitrogen loading rates are based on the
annual harvest of a nitrogen demanding crop. On unharvested spreading sites it is possible that
over a period of time, the supply of available nitrogen will exceed crop uptake of nitrogen. This
would result in an increase in the amount of nitrates leaching into the groundwater. The potential
contamination of groundwater on such sites could be avoided by rotating the unharvested sites so
that a site with an excess of inorganic nitrogen could be used for production of a nitrogen de-
manding crop after an appropriate resting period.
Site location is important for minimizing odors, runoff, and groundwater contamination. The
site should be in an isolated location and should be at least 300 feet away from wells, springs,
intermittent streams, streams, rivers, ponds, lakes, marine waters, and floodplains. The slope of
the land selected for the disposal site should be less than 8 percent. Holding facilities or
alternative disposal plans may be required where climatic conditions preclude land spreading year-
round.
In addition to the above design considerations, equipment selection and sizing must be in-
cluded for subsurface application of septage. Additionally, immediate incorporation of septage
minimizes nitrogen loss due to volatilization, and thus, net nitrogen loadings to the soil
generally will be higher for subsurface disposal than surface application. To reduce buildup of
nitrogen in soil and potential groundwater contamination, a nitrogen demanding crop should be grown
and harvested on the site.
The location, design, and operation of sanitary landfills are governed by the criteria
established by states. For landfills receiving septage, some standard operating criterias are as
follows.
o New Jersey recommends an application ratio of 10 gallons of septage to each cubic yard of solid
wastes. California regulations allow 25-40 gallons/cubic yard of solid wastes (7).
I-A-48
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SEPTAGE DISPOSAL BY LAND APPLICATION
October 1980
FACT SHEET 3.1
o The New England Interstate Water Pollution Control Commission (NEIWPCC) recommends that the
landfill include facilities for the collection and treatment of leachate.
o The NEIWPCC recommends a 6 inch earth cover be applied daily to each area that was closed with
septage and 2 feet final cover placed within a week after the placement of the final lift (23).
o The groundwater should be monitored on a regular basis to determine any change in groundwater
quality due to septage loading.
Disposal trenches are three to six feet deep and two to three feet wide, with lengths varying
with site location. Sufficient space is left between trenches to allow movement of heavy equip-
ment. Septage should be added in lifts six to eight inches deep, depending on soil condition.
After the trench is full with dried solids, the trench should be covered with at least two feet of
soil.
The site selection should include consideration of soil type and characteristics, groundwater
depth, acquifer size and use, proximity to dwellings, and proximity to septage sources. A minimum
of four feet between seasonal high groundwater and trench bottom is recommended. A monitoring
strategy to monitor groundwater contamination should also be included.
RELIABILITY
Properly managed land application of septage is a reliable means of disposal.
ENVIRONMENTAL IMPACT
Potential detrimental environmental impacts include contamination of soil, water (surface and
ground) air, vegetation, animal life and, ultimately, humans. Surface application presents more
problems for surface water and air contamination than other methods but can be controlled by plant-
ing and harvesting a crop high in nitrogen uptake and by preventing application during wet periods
when surface runoff would be greatest. Subsurface applications, landfills, and trenches pose a
bigger threat to groundwater supplies. Proper site selection can mitigate against such impacts.
REFERENCES
91, 23, 99, 11, 85, 7, 4, 86, 89, 94.
DIAGRAM
LAND APPLICATION OPTIONS FOR SEPTAGE DISPOSAL
EH
D-
D-
D-
D-
D-
CH
INDIV
SEPT
(DUAL
1C TANK
1 ("SANITARY
PUMPING
AND
HAULING
TRUCK
S
LANDFILL 1
| SURFACE APPLICATION |
1 SUBSURFACE APPLICATION 1
1
1 DISPOSAL
: — : — i
TRENCHES |
I-A-49
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SEPTAGE DISPOSAL BY LAND APPLICATION FACT SHEET 3.1
October 1980
COSTS
Surface application: $1.50-$20.00 per 1,000 gallons of septage (not including transportation
to site).
Subsurface application: $25,000-$42.50 per 100 gallons of septage (transportation not in-
cluded).
Sanitary landfill: $5.00-$10.00 per 100 gallons of septage (accurate costs not available).
Septage often not accepted at landfills due to low solids content.
Disposal trenches: $25.00-$36.50 per 1,000 gallons of septage (transportation not included.
Site life assumed to be 10 years. Facility capacity assumed to vary from 100,000 gallons/yr to
250,000 gallons/yr).
1980 dollars; ENR = 3260 reference (94).
I-A-50
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SEPTAGE TREATMENT AND DISPOSAL AT SEPARATE SEPTAGE FACILITIES FACT SHEET 3.2
October 1980
DESCRIPTION
Septage treatment facilities generally are regional facilities in areas where high densities
of septic tank systems exist. Only a small portion (approximately 1 percent) of the total septage
generated nationally is treated in separate septage treatment facilities. The process types cur-
rently in operation include lagoons, composting, and chemical treatment.
Lagoons are among the least expensive methods available for disposing of septic tank wastes,
and are widely used throughout the country. The lagoon disposal system normally consists of two,
three-feet deep earthen basins arranged in series. The first lagoon serves as the primary settling
basin in which the majority of suspended solids accumulate, settle, and undergo further anaerobic
digestion. The adjacent lagoon serves as the seepage lagoon from which supernatant from the
settling lagoon is discharged. The supernatant infiltrates the soil where it undergoes further
purification. An alternative lagoon system consists of a settling lagoon followed by percolation
beds. These beds consist of a layer of sand over soils with good percolation characteristics. The
beds have a berm running along the perimeter to retain the liquid. Once the lagoon is full, the
liquid is allowed to percolate and evaporate until solids are dry enough for removal and ultimate
disposal. Alternatively, the lagoon may be covered with topsoil and a new lagoon opened at
another site. The lagoons will gradually lose their capacity to infiltrate water due to clogging
of the soil. Returning a clogged lagoon to operation may require cleaning, scrapping, and re-
grading.
Septage can be converted to a compost product, which is a well stabilized, odorless material
with a much wider range of uses than raw septage. The conversion process involves mixing septage
with a suitable bulking agent (wood chips and/or sawdust), and circulating air through the mixture
to insure proper conditions for pathogen die-off, decomposition of organics, and odor reduction.
The process is carried out in three stages that include digestion, drying and screening, and cur-
ing. In the digestion stage, the compost pile is aerated and undergoes decomposition by ther-
mophilic organisms. The digestion stage is completed in about 21 days at which time the compost is
either dried or cured depending on weather conditions. The drying and screening stage involves
spreading the compost pile to a depth of 12 inches for drying to 40 to 45 percent moisture content.
The compost is then separated from the wood chips by screening through a rotary screen and the wood
chips are recycled. Curing is the final stage in which the compost is stored in piles for about 30
days to insure that no offensive odors remain and to complete stabilization.
Chemical treatment of septage is used to improve solid-liquid phase separation, improve de-
waterability, reduce odors, or kill pathogens. Chemical treatment processes include:
o Chemical coagulation
o A two-stage chemical process involving acidification followed by lime treatment
o Rapid chemical oxidation
o Lime stabilization.
Chemical coagulents such as ferric chloride, alum, lime, and polyelectrolytes are added to septage
to cause a solid-liquid phase separation and to improve the dewatering characteristics of septage.
Coagulant addition takes place in rapid mix tanks. The coagulant reacts with water molecules to
form polymers that trap suspended solids and then precipitate out in settling tanks.
The two-stage chemical process involves acidification of septage to cause solid-liquid phase
separation. The liquid (supernatant) portion from the settling tank is treated with lime prior to
final disposal.
Rapid chemical oxidation of septage uses heavy doses of chlorine to oxidize the septage. The
relatively inert residue is clarified, and then dewatered by vacuum filtration, lagoon or drying
beds.
Lime stabilization of septage involves the addition of lime slurry to raise the pH of the
material. The process consists of septage collection, mixing, and reaction with lime to pH 12.
The stabilization may be followed by a dewatering step, or the stabilized liquid septage may be
spread on the land. The stabilized septage is low in pathogens, its odors are eliminated, and the
organics do not decompose easily.
I-A-51
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SEPTAGE TREATMENT AND DISPOSAL AT SEPARATE SEPTAGE FACILITIES FACT SHEET 3.2
October 1980
Chemical treatment processes generally are preceded by pretreatment of the septage. The
liquid and solids that separate after chemical addition may require additional treatment prior to
disposal.
COMMON MODIFICATIONS
Lagoons: Many disposal sites have two sets of lagoons in series. One set may be dewatered
and scrapped while the parallel set handles the incoming septage. Some lagoon operators apply
septage in thin layers. Each layer is allowed to dewater before another is applied. In some cases
each layer is covered with soil to help reduce odor and facilitate final covering or cleaning.
Composting: Lebo System - The patented Lebo process consists of aerating septage and then
spraying it on piles of sawdust, wood shavings, or other dry organic material. A one- to two-inch
application of septage is covered with additional sawdust, and alternating layers of septage and
sawdust are formed into a pile. The pile is composted using natural draft aeration for about three
months.
Beltsville System - The Beltsville "static pile method" is used to compost dewatered municipal
sludge and could be used for septage composting. The process consists of mixing septage with a
bulking agent (sawdust, wood chips, or other material). The mixture is placed in a pile on a base
consisting of an aeration header covered by 12 inches of wood chips or unscreened, previously
composted material. The pile is covered with a 12-inch layer of screened compost to provide insu-
lation and prevent odors from escaping. The pile is aerated by pulling or pushing air through the
header. A three-week composting period is followed by a four-week curing period. Bulking material
can be recovered by screening after the composting or curing stage.
TECHNOLOGY STATUS
Lagoons for septage disposal are fully developed technologically. The Lebo system has been
used for composting septage at several locations in Washington (23). Septage composting by the
Beltsville method has been performed at the pilot level only (7).
Raw septage is chemically treated with lime and ferric chloride at an Islip, Long Island, N.Y.
facility. The plant has experienced difficulty in producing an effluent of consistently good
quality (99). Laboratory and pilot scale studies on treatment of septage (90) have demonstrated
that raw screened septage can be coagulated with a number of chemicals such as ferric chloride,
alum, lime, acid, or combinations of the above. However, optimizing the dosage of ferric chloride,
alum and lime to achieve effective phase separation is difficult. Effective phase separation can
be consistently achieved by the application of a two-stage sulfuric acid/lime coagulation process
(90).
Chlorine oxidation is used in a number of areas to treat septage and septage/sewage sludge
combinations. Existing chlorine oxidation installations have had operational problems including
poor solids separation, odor, and mechanical problems (99).
Lime stabilization of septage has been demonstrated in two research projects by EPA (25).
Obtaining acceptable septage dewatering on sand drying beds requires large amounts of lime (^ 180
pounds per ton of dry solids).
APPLICATIONS
Lagoons can be used as a method of septage disposal or as independent septage treatment faci-
lities, with ultimate disposal of supernatant and solids by other means.
Composting is suitable for liquid septage of dewatered septage. Its low capital cost and
simple process facilitates small operation in rural areas near septage generation points.
Chemical treatment processes can be used at independent septage treatment plants with complete
facilities for receiving, holding, chemical treatment, and final disposal of the solids and liquid.
For most small towns, a system of this type could be operated on a batch basis and would require
only a part-time operator. For large installations operated on a continuous basis, a full-time
operator would be required.
I-A-52
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SEPTAGE TREATMENT AND DISPOSAL AT SEPARATE SEPTAGE FACILITIES FACT SHEET 3.2
October 1980
LIMITATIONS
Lagoon disposal systems require some form of centralized management organization to finance,
construct, and operate the facility.
A market is needed to handle large volumes of compost. In a municipal facility, compost
application on parks and golf courses as a soil conditioner has been acceptable. The process also
requires large volumes of bulking agents which must be readily available at a reasonable cost.
A chemical handling and feed system requires a high degree of operator attention. Chemical
treatment processes are capital intensive and costly to operate. Therefore, they can be located
only in areas where there are high densities of septic tanks so as to achieve economies of scale.
TYPICAL EQUIPMENT
Lagoons: Front-end loader or other sludge removal equipment.
Composting: Front-end loader, blower, tractor-drawn harrow, rotary screen.
Chemical treatment: Chemical storage tanks, mixing tanks, chemical feed equipment, pumps,
instrumentation.
PERFORMANCE
Operating problems with lagoons, such as clogging of the sand at the bottom, have been re-
ported (91).
During composting, septage is converted to a relatively stable organic residue. Maximum
tempera tures of between 60° and 80°C produced during the first three to five days of stabilization
can destroy pathogens. The Rehoboth pilot project (47) has successfully demonstrated septage
composting. Due to the high moisture content of septage (generally 90 percent), high water absorb-
ing materials are necessary as bulking agents.
The pilot plant studies on chemical conditioning of raw screened septage with ferric chloride,
lime, alum, acid or combinations of the above, has indicated effective separation in six to eight
hours (90). Research at the EPA-Lebanon Pilot Plant has shown that lime stabilization of septage
at pH 11.5, followed by sandbed dewatering, is a technically feasible septage treatment method.
Effective fecal coliform reduction was achieved at pH 11.5 and pathogenic Salmonella species and
Pseudomonas aeruginosa in raw septage were destroyed (99).
DESIGN CONSIDERATIONS
Proper siting and installation of the lagoon is essential to avoid adverse environmental
impacts. Siting criteria vary from state to state. The following general guidelines established
by the New England Interstate Water Pollution Control Commission provide some of the considerations
associated with the planning and design of septage lagoons (100).
o Buffer zone - site must be surrounded by a 300-foot buffer zone.
o Groundwater protection - base of lagoon should be located at least 4 feet above the maximum
groundwater table (in New Hampshire, the distance is 10 feet).
o Minimum lagoon depth - at least 3 feet deep.
o Access - access to the site should be by all-weather roads.
o Fencing and signs - fencing at least 6 feet high with locking gate is required. Warning signs
must be posted on all sides of the facility.
o Lining - the bottom of the lagoon should be lined with at least 1 foot of good, filterable sand
o Septage receiving port - there should be concrete receiving chambers. The scavenger trucks
should have accommodations for vertical discharges into the chamber. The septage should be
introduced below the liquid surface through a horizontal discharge pipe.
o Hydraulic gradient - the lagoon should have approximately 1/3 of its volume located above ground
level to facilitate cleanout processes.
o Monitoring - volume and operating level should be monitored with a staff gauge. A groundwater
and surface water quality monitoring program should be included in the vicinity of the site.
I-A-53
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SEPTAGE TREATMENT AND DISPOSAL AT SEPARATE SEPTAGE FACILITIES FACT SHEET 3.2
October 1980
o Grading - the site should be adequately graded to prevent surface runoff from entering the
lagoons.
o Flow patterns - a minimum of two lagoons in series is recommended. Parallel lagoons are recom-
mended so that one series of lagoons can be used while the other is being cleaned out.
Land requirements for composting depend on the quantity of septage to be treated. The faci-
lities should include: septage receiving station and storage, bulking agent storage, mixing area,
composting pads, screening system, compost curing and storage, and leachate handling.
The septage receiving station should be easily accessible by pumper trucks, and should provide
coarse screening and adequate clean-up facilities. Septage storage tank capacity should be ade-
quate for two-day peak volume. Bulking agents are needed for septage composting including sawdust
and wood chips. Due to the high moisture content of liquid septage, sawdust is used as the primary
bulking agent. Approximately 50% moisture content is desirable in septage/bulking agent mixtures.
Pilot studies indicate a bulking agent requirement of 6 to 9 cubic yards per 1,000 gallons of
septage (7). The Rehoboth pilot project used 4 cubic yards of sawdust, 3 cubic yards of wood
chips, and 2 cubic yards of cow and/or horse manure per 1,000 gallons of septage (47). The mixing
of a bulking agent and septage can be accomplished manually (front-end loader) or mechanically (pug
mill).
The compost pile should be aerated and monitored to maintain oxygen levels of between 5 and 15
percent in the pile. The forced aeration system consists of 4 to 6 inches of perforated pipe,
moisture trap, 1/3-hp blower, small compost pile for odor removal, and ancilliary piping. The
successful composting operation is governed by three operational parameters: carbon to nitrogen
ratio, moisture content, and temperature. Carbon to nitrogen (C:N) ratios determine the rate of
composting if adequate moisture content is maintained. C:N ratios of 20 to 30:1 have been sug-
gested as ideal (7). The Rehoboth pilot project, which used cow and/or horse manure as a nitrogen
source in a septage sawdust mixture, was judged to have an extremely high C:N ratio (47). A mois-
ture content of between 45 to 65 percent is desirable. The compost pile should reach and maintain
a temperature of 60°C for effective pathogen destruction.
The dosages required for chemical treatment are as follows:
o Lime - The quantity of lime required for stabilization is variable depending on the alkalinity
and solids concentration of the septage. For pH 12 stabilization, quantities of lime ranging
from 0.1 to 0.3 Ib lime/lb dry solids are required. For septage with 5 percent solids content,
quantities range from 42 to 125 Ib lime/1,000 gallons septage (40)
o Chlorine - Doses vary from 700 to 3,000 rag/1 depending upon the solids content and the amount of
chlorine-demanding substances present (i.e., ammonia)
o Ferric Chloride - Consistantly desirable separation of liquids and solids was achieved with
doses of 400 to 600 mg/1. The supernatant from ferric chloride treatment can be improved fur-
ther by adding lime in doses of 2,500 to 4,000 mg/1 (90)
o Alum - Laboratory investigations have indicated that optimum alum does (as A1«[SO,] ) range from
2,250 to 8,250 mg/1, depending on the initial septage characteristics (90)
o Acid - Average sulfuric acid requirements to adjust and maintain pH 2.0 range from 3,000 to
4,000 rag/1 (90).
The chemical dosages vary with the characteristics of the septage and thus should be determined by
jar tests, except for lime and acid which are determined on the basis of pH of the mixture. Chemi-
cal feed equipment must be sized for maximum chemical demand.
RELIABILITY
The Lagoon process is simple and little operator expertise is required. The major problem is
that high solids carry-over into the second lagoon may result in clogging of the infiltration
system. This problem is due to the poor settling properties of septage and excessive loadings
(90).
I-A-54
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SEPTAGE TREATMENT AND DISPOSAL AT SEPARATE SEPTAGE FACILITIES
October 1980
FACT SHEET 3.2
Composting has a high degree of process reliability because the process is simple to operate.
Chemical processes are capable of producing consistently good results if chemical dosages are
optimized and if the process is properly controlled. This requires above average operator atten-
tion.
ENVIRONMENTAL IMPACT
Odor and groundwater contamination are potential problems with septage lagoons. Odors can be
a particular problem when trucks are discharging septage and when lagoons are being cleaned. Odors
can be minimized by adding septage to lagoons below the liquid level, and controlled by adjusting
the pH of the lagoon periodically to 7-8 by adding lime. Lagoons using leaching as a means of
liquid disposal require high rates of percolation, and thus, are located in very well-drained
soils. Unfortunately, most well-drained soils generally are less capable of renovating the perco-
lating water, which increases the potential for groundwater contamination.
Potential odor problems during mixing are possible with composting. Leachate could
contaminate surface and groundwater if proper collection, treatment, and disposal are not provided.
Chemical oxidation with chlorine has the potential to produce chlorinated organic compounds
which could have severe environmental impacts. Disposal of chemically treated septage on land has
the potential to contaminate groundwater and the soil.
REFERENCES
91, 23, 99, 11, 100, 85, 7, 47, 90, 25, 40.
CHEMICALS REQUIRED
One or more of the following chemicals are required for chemical treatment of septage: lime
(CaO or CA(OH) ), ferric chloride (Fed-), alum (Al SO,), sulfuric acid (H So,) , chlorine (Cl),
ferric sulfate TFeS04), polymers. ^ L *
RESIDUALS GENERATED
Settled solids on the lagoon bottom are removed and buried in another location or spread on
the land; alternatively the solids are left in the lagoon and covered with soil.
DIAGRAM
LAGOONS
Or
TRUCK
DISCHARGE
PORT
SETTLING
LAGOON
OR
PERCOLATION
LAGOON
PERCOLATION
BEDS
COMPOSTING
O
SEPTAGE
RECEIVING
STATION, PRE
TREATMENT
AND STORAGE
DISTRIBUTION
OF COMPOST
BULKING AGENTS
I-A-55
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SEPTAGE TREATMENT AND DISPOSAI AT SEPARATE SEPTAGE FACILITIES
October 1980
FACT SHEET 3.2
CHEMICAL TREATMENT
SEPTAGE
RECEIVING
STATION ,PRE-
TREATMENT,
AND STORAGE
CHEMICALS
SOLIDS
DEWATERING
LIQUIDS
FINAL
DISPOSAL
LIQUIDS
SOLIDS
FINAL DISPOSAL
OF SOLIDS
COSTS
The cost for lagoon disposal, based on several engineering studies, ranges from $6 to
$25/1,000 gallons of septage (updated to 1980 dollars). The greatest cost determining factors are
land costs and solids disposal costs. The operational cost would increase if groundwater moni-
toring were required (7). The estimated costs (converted from 1977 dollars to 1980 dollars) of
parallel storage basins, consisting of discharge ports and flow diverting structures; three basins,
each with usable volumes of 470,000 cu ft; and, a supernatant infiltration area, are as follows
(11).
QUANTITY OF WASTE COLLECTED
MILLION GAL/YR
1.0
1.5
2.0
2.5
FIXED
7,850
7,850
7,850
7,850
ANNUAL COST
VARIABLE TOTAL
$ $
4,950
6,850
8,850
10,650
12,800
14,700
16,700
18,500
COST/1000 GAL
$
12.80
9.80
8.35
7.40
The fixed costs include earth moving, grading of the infiltration channel, receiving tank and
screen, dumpster, fence, controlled access equipment, water supply, concrete apron, access road,
and land. The variable costs include labor, trash disposal (for screenings), sludge removal, and
land spreading of dried sludge.
The total amortized cost (updated to 1980 dollars) for septage composting based on design
studies varies from $30 to $50 per 1,000 gallons (7). This cost does not include income from the
sale of the compost product.
I-A-56
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SEPTAGE TREATMENT AND DISPOSAL AT SEPARATE SEPTAGE FACILITIES FACT SHEET 3.2
October 1980
U.S. Department of Agriculture research on the composting of sludge has indicated that the
cost per dry ton sludge is sensitive to changes in operating costs, but insensitive to equipment,
land, and site development costs. The operation is labor intensive. For 10 dry tons of sludge per
day, dewatering facility labor costs are 43% of the total annual cost and 52% of the annual
operating cost. Wood chips account for 24% of the annual operating cost (7). For composting of
undewatered septage, sawdust is required as a liquid absorbent, which, unlike wood chips, cannot be
recovered and reused. This sawdust represents a significant portion of the annual operating cost.
If the septage were dewatered to 20 to 25% solids, little sawdust would be required, and woodchips
could be used and recovered up to four times.
The cost (converted from 1978 to 1980 dollars) for a 2,500 GPD chemical treatment facility
designed for septage treatment exclusively, has been estimated at $44 per 1,000 gallons of septage
(90). The facility includes screening and equalization of raw septage, application of the acid/
lime addition process, aqueous fraction treatment by intermittent sand filtration, and sludge
dewatering by sand drying beds. Several cost estimates have been made for chemical treatment
plants, all of which appear to be greater than $30/1,000 gallons septage. A reported cost (updated
from 1975 to 1980 dollars) for lime stabilization and sand drying bed dewatering has been estimated
at $44/1,000 gallons septage (25). Cost estimates (updated from 1977 to 1980 dollars) for a lime
stabilization facility with land spreading ranged from $15.30 (2.5 million gallons per year col-
lection) to $22.50 (1.0 million gallons per year collection) for 1,000 gallons of septage. The
cost estimate included: septage receiving tank, bar screen, storage basin, chemical feed system,
mixer tank, and land (11). Estimates of the total amortized cost (updated from 1978 to 1980 dol-
lars) for chlorine oxidation septage ranged from $35 - $70 per 1,000 gallons (7). The cost varies
with the size of the facility, type of dewatering technique selected, cost of chlorine, method of
cake disposal, and need for leachate treatment/disposal.
I-A-57
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SEPTAGE TREATMENT AND DISPOSAL AT WASTEWATER TREATMENT PLANTS FACT SHEET 3.3
October 1980
DESCRIPTION
Disposal of septage at wastewater treatment plants is estimated to account for up to 25
percent of the total septage generated; in most cases disposal is accomplished by addition to the
liquid stream. However, in some instances septage is handled in the sludge stream and is processed
alone or in combination with sewage treatment plant sludge.
Septage is treated in the conventional wastewater treatment plant by adding it to the
liquid stream of the plant. The septage can be added to a manhole upstream in a collection system,
added as a slug to the headworks of the treatment plant, or added at a controlled rate to the
influent stream.
Septage addition to an upstream manhole as a slug is usually preferable to slug addition at
the headworks. Upstream addition provides for better dilution of the septage with sewage, and
minimizes organic shock to the biological processes and possible upset of the plant. However,
addition of septage to manholes is difficult to control and regulate. Uncontrolled upstream dump-
ing of large volumes of septages may have a deleterious impact on plant operation and effluent
quality. In addition, incidences of sewer clogging due to grit and debris contained in the septage
have been reported (91).
Direct discharge of septage to the headworks of the plant in quantities of 1,000 or more
gallons is practiced at many plants throughout the country (91). The procedure, though simple, has
been known to cause upsets in plant performance due to temporary hydraulic or organic overloads,
clogging or fouling of the plant equipment, or by exceeding the solids handling capacity of the
plant.
Controlled addition of septage through the use of a holding tank is the recommended method.
This allows slow introduction of septage into the mainstream, thereby minimizing the impact on the
plant. This method includes a receiving station for easy and safe transfer of septage from the
hauler truck, pretreatment (e.g., screening) to protect the equipment downstream, a holding tank to
store and equalize the septage, and pumps to add septage from the holding tank at a controlled
rate.
Septage is about 50 times as concentrated as domestic sewage, and loadings of solids and
oxygen-demanding substances to the treatment process can increase substantially during septage
addition. The additional solids loading due to septage may result in detrimental effects on pri-
mary and secondary settling, as well as dewatering of undigested sludge (91). The additional
oxygen-demanding load could depress the dissolved oxygen level to zero, and result in plant upset.
The treatment plant should have sufficient reserve aeration capacity to accommodate the increased
oxygen demand associated with septage.
Septage is added to the sludge stream of the wastewater treatment plant and is treated and
processed as a sludge. This may involve such processes as thickening, aerobic and anaerobic diges-
tion, grinding, dewatering, and final disposal. The addition of septage to the sludge handling
system at the plant avoids possible problems with pumping, biological overloading, and generation
of greater sludge volumes for final disposal.
TECHNOLOGY STATUS
Treatment by addition to the liquid stream of a sewage treatment plant is a common method of
handling septage. Approximately 2.5 million gallons of septage were dumped in wastewater treatment
plants in Vermont during 1976 (98). Of the 21 plants in Vermont that had received septage in 1976,
half were primary treatment plants and half were secondary treatment plants. In addition, several
new treatment plants in Vermont, which are presently in various stages of design and construction,
are incorporating septage receiving and treating facilities.
Several researchers report good results for aerobic digestion of septage or septage-sewage
sludge mixtures (23). Many treatment facilities throughout the county have treated septage-sewage
sludge mixtures in aerobic digesters with generally satisfactory results, although some investi-
gators report odor and foaming problems (99). Septage from holding/pretreatment facilities has
been added to anaerobic digesters in Westport, Connecticut, and the digesters have operated with
good results (99). Bench scale study of anaerobic digestion of septage mixed with treatment plant
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SEPTAGE TREATMENT AND DISPOSAL AT WASTEWATER TREATMENT PLANTS FACT SHEET 3.3
October 1980
sludge has demonstrated that the digesters function well except for a digester loaded with 100
percent septage (99).
APPLICATION
Most sewage treatment plants with biological treatment processes are able to treat septage in
the liquid stream. Extended aeration plants, often found in rural areas, are able to handle
septage relatively well if sufficient reserve aeration capacity is present. Long detention times
in aeration tanks provide for sufficient biological assimilation resulting in acceptable reductions
of the BOD and suspended solids. A conventional activated sludge system with a primary clarifier
can effectively treat septage as long as organic and solids handling design capacity is not ex-
ceeded. The primary clarification facilities preceding the activated sludge process help to level
out the fluctuations in loadings imposed by septage addition on the biological process.
Contact stabilization appears to be least amenable for treating septage by addition to the raw
wastewater flow. This is due to the short retention time, the high soluble organic content of
septage, and the high grease content of septage (99). However, addition of screened septage at a
controlled rate to the contact and reaeration zone of a plant operating at 20 percent of design
capacity has been demonstrated to result in minor changes in the final effluent quality (90).
Attached growth processes, such as trickling filters and rotating biological contactors, are
more resistant to upsets from changes in organic or hydraulic loadings, and are suitable for
septage treatment (86). The major concerns with adding septage to trickling filter plants are odor
generation, filter clogging, and filter fly proliferation. Additional recirculation in trickling
filters has been shown to adequately dilute septage concentrations and diminish chances of plugging
the media.
Septage addition to aerobic digestion with the treatment plant sludge should follow screening,
degritting and flow equalization. For addition to single-stage anaerobic digestion, pretreatment
and equalization is necessary.
LIMITATIONS
The quantity of septage that a wastewater treatment facility can handle is normally limited by
the plant's available aeration and/or solids handling capacity. In most rural areas, sewage treat-
ment plants have a limited capacity and handle significant volumes of locally-generated septage.
To avoid adverse impacts of septage addition on plant performance, a septage holding and controlled
feeding facility should be provided. Sludge processing units should have adequate capacity to
handle the additional load from septage.
PERFORMANCE
An experimental pilot plant study has evaluated septage addition to the liquid stream of an
activated sludge treatment process using two approaches (87). The first approach added septage on
a continuous basis to a system receiving a combination of septage and sewage in varying ratios.
The second approach added septage on a shock load basis to a system treating municipal waste only.
In both approaches, primary sedimentation was simulated prior to adding septage to the activated
sludge. The study indicates that septage addition as either a continuous or intermittent basis is
feasible if sufficient oxygenation and sludge handling capacities are available, and control of the
waste mixed liquor suspended solids is possible. The particular response of the continuous flow
activated sludge system receiving septage depends upon organic loading and septage characteristics.
Unacclimated systems were not unduly upset by septage addition, and substantial removals of septage
were obtained within a relatively short time. Septage addition monitored at three wastewater
treatment plants indicated that septage is a readily treatable waste at extended aeration and
conventional activated sludge plants (93) .
Aerobic digestion of septage with BOD reduction of 80 percent and a volatile suspended solids
(VSS) reduction of 41 percent after a 10-day aeration time; and, COD reduction of 75 percent and
VSS reduction of 43 percent after 22 to 63 days aeration, have been reported for sludge stream
additions (23). Dewatering and settleability have also been found to improve with aeration, but
the aeration time required to affect significant improvement varied. Anaerobic digestion of
septage in an unheated 20°C to 30°C digester resulted in volatile solids reduction of 56 percent
after an 82-day retention time and a loading of 0.01 pound VSS/cf/day (23).
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SEPTAGE TREATMENT AND DISPOSAL AT WASTEWATER TREATMENT PLANTS FACT SHEET 3.3
October 1980
A bench-scale anaerobic digester loaded at 0.05 pound VSS/cf/day with a 15-day hydraulic
retention time resulted in 45 percent reduction in VSS.
DESIGN CONSIDERATION
The quantity of septage that a wastewater treatment facility can handle is normally limited by
the plant's available aeration and/or solids handling capacity. Aeration capacity is most critical
at extended aeration plants where the entire quantity of septage undergoes oxidation. Recommended
levels of septage addition to different types of activated sludge plants should be followed. In
general, conventional activated sludge plants are able to treat septage at about four times the
rate of package plants (23). Conventional activated sludge plants with primary clarifiers function
well with either constant or shock loading, whereas extended aeration plants function better with
additions of septage at constant rates (93). Constant addition of septage requires a storage and
septage transfer system.
A new wastewater treatment facility designed to receive septage should include provisions for
the additional dissolved oxygen requirements and increased sludge production as a result of septage
addition.
There is limited information in the literature regarding acceptable septage loading rates and
septage/sewage ratio for aerobic and anaerobic digesters. Septage addition to anaerobic digesters
between 5 and 13 percent of total sludge flow has been reported (23). It is also recommended that
the initial septage addition to an aerobic digester be limited to approximately 5 percent of the
existing sludge flow followed by gradual increases (23).
ENVIRONMENTAL IMPACT
Septage is highly odoriferous and is a health hazard. Personal contact with septage is highly
undesirable.
REFERENCES
91, 23, 99, 7, 86, 93, 90, 98, 87.
RESIDUALS GENERATED
Septage addition to wastewater treatment plants results in a significant increase in sludge
production. At a volumetric septage input of 1 percent of the plant flow, the theoretical sludge
production rate can be expected to increase about 50 percent (7). A septage monitoring study has
indicated a direct relationship between total solids in combined sewage-septage influent and sludge
cake production. A 46 percent increase in total solids resulted in a 41 percent increase in cake
solids production (93). Addition of septage may also increase amounts of scum and grit.
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SEPTAGE TREATMENT AND DISPOSAL AT WASTEWATER TREATMENT PLANTS
October 1980
FACT SHEET 3.3
DIAGRAM
SEPTAGE TREATMENT AT WASTEWATER TREATMENT PLANTS
(SOLID AND LIQUID STREAM ADDITION)
SEPTAGE ACCEPTING
FACILITY INCLUDING
PRETREATMENT 8
HOLDING
•^-LANDFILL
SUPERNATENT
RETURN
COSTS
A nationwide survey of the charges levied for disposing of septage in 42 wastewater treatment
plants has indicated that the disposal charges vary from $5 to more than $35 per 1,000 gallons,
with an average charge of slightly more than $15 per 1,000 gallons (99). These data indicate that
the cost of the septage hauler actually pays for dumping septage in a WWTP, but they probably do
not accurately represent the actual cost of treating the septage in WWTPs. The actual cost of
treating septage in WWTPs, based on engineering cost estimates, ranges from $2 to $38 (1977
dollars) per 1,000 gallons with an average of $23 per 1,000 gallons (99).
Septage treatment costs can be divided into three categories: capital equipment, operation
and maintenance, and disposal site acquisition. Capital costs include the cost of solids handling
equipment, aeration facilities, and septage receiving stations. Operating costs include labor,
power, and possibly additional chemical requirements. Operating and maintenance costs largely
depend on whether a plant has primary clarification, and on available economies of scale. The
operation and maintenance cost of treating septage at a 1.5 MGD extended aeration facility is
between $8 and $12 per 1,000 gallons, and the cost at a 5.5 MGD two-stage activated sludge plant
with primary clarifier is about $2 per 1,000 gallons (93). Septage addition in both cases was 2
percent of the sewage flow. The cost difference was attributed to the high power cost of oxidizing
septage organics in an extended aeration facility and the economic advantages inherent at the
larger plant.
Engineering cost estimates (99) for treating septage with sewage sludge vary from $2 to $19
(1977 dollars). The cost depends on the size of the treatment plant, quantity of septage in rela-
tion to quantity of sewage sludge, type of stabilization process (aerobic or anaerobic) chemical
requirements, and mode of final disposal.
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WETLANDS APPLICATION OF WASTEWATER FACT SHEET 4.1
October 1980
DESCRIPTION
The application of wastewater to wetlands is a method of renovating wastewater through an
ecosystem which involves plant and animal reactions in addition to physical and chemical inter-
actions. Wetlands are fresh water or salt water and are naturally occurring or artificially made.
Natural wetlands can vary according to source of water (surface, ground, rain, and tidal) and to
the flow characteristics (inflow/outflow, no inflow/outflow, or no inflow/no outflow). Artificial
wetlands are classified as marshes, marsh-ponds, ponds, or trenches (lined and unlined). Wetlands
have been used predominantly for treatment of wastewater that has already been treated to secondary
standards (83). Plant and animal organisms reduce BOD and utilize the nutrients in wastewater.
COMMON MODIFICATIONS
Modifications include various methods of application of the wastewater to the wetlands such as
point discharge, overland flow, and ridge and furrow application. Specific site constraints
dictate the selected method. Additional modifications are based on the point in the treatment
process scheme at which wetlands are used. Wetlands can be used as tertiary treatment following a
secondary treatment process, or as a secondary treatment process following primary treatment only.
Artificial and natural wetlands can also be used in conjunction with one another to complete a
treatment scheme.
TECHNOLOGY STATUS
Wetlands have been used specifically for wastewater disposal since the early 1960s. Because
of the varying design requirements for specific sites, and hence the lack of consistent design
criteria, the technology is not fully developed.
APPLICATIONS
Wetland discharge can be used for small communities where an advanced degree of treatment is
required and high groundwater (or other constraint) precludes the use of a subsurface disposal
cluster system.
LIMITATIONS
An obvious limitation to wetland discharge is the requirement for a suitable site for natural
or artificial wetlands.
TYPICAL EQUIPMENT/NUMBER OF MANUFACTURERS
Construction of pretreatment processes and distribution systems are locally supplied through
contractors.
PERFORMANCE
A great deal of confusion exists in the reporting of performance data for natural and
artificial systems used for the treatment of wastewater. In most cases, the data are so confounded
in a statistical sense that little or no usable information can be derived. Further, there is no
standardization regarding the basis on which performance data are reported. For example, in some
articles, performance data are reported as a function of time, while in others as a function of
distance. Usually, no basis or information is given on how time and distance are interrelated.
Further, the data for most of the natural systems are extremely site-specific and should not be
generalized (83) .
Recognizing these limitations, the removal ranges for the constituents of concern in waste-
water are reported in the following table (83). From a review of the limited data presented, it
can be concluded that that performance of wetlands with respect to most constituents of concern is
not well defined. Further, the range of the values reported is also of concern, especially the
lower removal efficiencies (83).
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WETLANDS APPLICATION OF WASTEWATER FACT SHEET 4.1
October 1980
REPORTED REMOVAL EFFICIENCY RANGES FOR THE CONSTITUENTS
IN WASTEWATER IN NATURAL AND ARTIFICIAL WETLANDS
Removal Efficiency,
Natural Wetlands Artificial Wetlands
Constituent Secondary Primary
Total solids 40-75
Dissolved solids 5-20
Suspended solids 60-90
BOD 70-96 50-90
TOC^ 50-90
COD 50-80 50-90
Nitrogen (total as N) 40-90 30-98
Phosphorus (total as P) 10-50 20-90
Refractory organics
Heavy metals3 20-100
Removal efficiency varies with each metal.
DESIGN CONSIDERATIONS
Few, if any, design criteria are available to accurately predict the performance of natural
wetlands or to properly size artificial wetlands for wastewater renovation. Land area requirements
are large and have been estimated at 30 to 60 acres per million gallons of wastewater (83). Be-
cause characteristics such as hydrology, hydrogeology, geology, and biology differ from site to
site, pilot plant studies are often the best method for determining design criteria. The following
table (83) lists preliminary design parameters for planning artificial wetland wastewater treatment
systems.
ARTIFICIAL WETLAND WASTEWATER TREATMENT SYSTEM3
PRELIMINARY DESIGN PARAMETERS FOR PLANNING
WATER TREATMENT SYSTE
Characteristic/Design Parameter
Detention Depth of Flow, Loading Rate,
Time, (d) ft (m) g/ft2d (cm/d)
Type of System Regime Range Typ. Range Typ. Range Typ.
Trench (with PF 6-15 10 1.0-1.5 1.3 0,8-2.0 1.0
reeds or rushes) (0.3-0.5) (0.4) (3.25-8.0) (4.0)
Marsh (reeds, AF 8-20 10 0.5-2.0 0.75 0.2-2.0 0.6
rushes others) (0.15-0.6) 0.25 (0.8-8.0) (2.5)
Marsh-pond
1- Marsh AF 4-12 6 0.5-2.0 0.75 0.3-3.8 1.0
(0.15-0.6) (0.25) (0.8-15.5) (4.0)
2- Pond AF 6-12 8 1.5-3.0 2.0 0.9-2.0 1.8
(0.5-1.0) (0.6) (4.2-18.0) (7.5)
Lined trench PF 4-20 6 - - 5-15 12
(hr.) (hr.) (20-60) (50)
^Based on the application of primary or secondary effluent.
PF = plug flow; AF = arbitrary flow.
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WETLANDS APPLICATION OF WASTEWATER
October 1980
FACT SHEET 4.1
RELIABILITY
Reliability problems in wetland treatment systems are related to changing climatic conditions,
variable wastewater characteristics, local environmental factors, and diseases that interrupt the
micro-organisms, plants and animals used in treating the wastewater. In some regards, the poten-
tial for and consequences of poor system reliability is greater in wetland systems than in conven-
tional systems because of greater environmental exposure. On the other hand, wetland systems may
be less prone to upsets caused by errors in operator judgment. With so few systems operating on a
long-term basis, reliability cannot be defined statistically (83).
ENVIRONMENTAL IMPACT
Techniques must be developed to mitigate against possible environmental impacts such as: (1)
the breeding and growth of disease (vectors, mosquitos, and flies); (2) induced populations of
plants and animals considered to be pests; and (3) the development of odors (83). If disinfection
is to be considered, the impacts of disinfectants on the ecosystem must be fully assessed. Addi-
tionally, secondary impacts due to the increase in certain species and the decrease in others must
be evaluated through pilot plant studies.
REFERENCES
83, 79, 42, 26, 84, 81.
DIAGRAM
Key: Conventional Primary:
Conventional Secondary:
= O
Wetlands:
D
D
Alternative process schemes using wetlands.
ENERGY NOTES
The following figure compiled from work by Tchobanoglous (84) compares total annual energy
requirements to plant size for four different aquaculture systems and a conventional activated
sludge plant. Total energy requirements include electricity and fuel as primary energy components.
Plant construction, chemicals, and parts and supplies are considered as secondary energy com-
ponents. Secondary energy requirements are based on a return period of 20 years. The purpose of
the figure is to show relative differences and not absolute values.
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WETLANDS APPLICATION OF WASTEWATER
October 1980
FACT SHEET 4.1
-
O o
u z
8
1.8
1.6
I 4
1.2
1.0
0.8
0.6
0.4
0.2
.ACTIVATED SLUDGE
CONSTRUCTION COST
VS
TREATMENT PLANT SIZE
ENR INDEX ' 3260
JULY 1980
ARTIFICIAL WETLAND
WATER HYACINTHS
0.2 0.4 0.6 0.8 1.0
TREATMENT PLANT SIZE (mgd)
1.2
(84)
OPERATION AND MAINTENANCE
Labor requirements in person-days for artificial wetlands and water hyacinths are presented
here, along with estimates for parts and supplies (84). Values for activated sludge are given for
purposes of comparison.
TREATMENT PLANT
Artificial Wetlands
Water Hyacinths
Activated Sludge
LABOR REQUIREMENTS
(PERSON-HOURS/YEAR)
PLANT SIZE (MGD)
0.1
500
1500
1600
0.5 1.0
1500 2000
2000 3000
3600 5500
PARTS & SUPPLIES
($/YEAR)
PLANT SIZE(MGD)
0.1 0.5 1^0
2300 2875 3450
2300 4025 5750
9200 13800 18400
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WETLANDS APPLICATION OF WASTEWATER
October 1980
FACT SHEET 4.1
u
2
9,000
8,000
7,000
6,000
5,000
3,000
2,000
1,000
TOTAL ENERGY REQUIREMENTS
(PRIMARY 8 SECONDARY)
VS
TREATMENT PLANT SIZE
CONVENTIONAL
ACTIVATED SLUDGE
AND CHLORINATION
RANGE OF ENERGY
REQUIREMENTS FOR
VARIOUS AQUATIC
TREATMENT
SCHEMES
I
I
I
I
I
0.2 0.4 0.6 0.8 1.0
TREATMENT PLANT SIZE (mgd)
1.2
(84)
COSTS
The following figure compares construction cost for complete treatment systems to treatment
plant size for activated sludge, artificial wetlands, and water hyacinths. Note that land costs
are not included which could he substantial considering acreage estimated for 0.1, 0.5, and 1 mgd
for artificial wetlands is 4, 20, and 40 acres, respectively. Acreage estimated for water hya-
cinths is 1/2 of the requirements for artificial wetlands while only 1/10 of the acreage required
for artificial wetlands is required for activated sludge plants. (84)
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CLUSTER SYSTEMS FACT SHEET 4.2
October 1980
DESCRIPTION
Cluster systems consist of transportation, treatment, and disposal of waste from a group of
homes. Transportation is accomplished through gravity, small diameter, pressure, or vacuum sewers.
Treatment takes place in septic tanks at individual homes or jointly at a selected site. The treat-
ment system can be lagoons, septic tanks, package aeration plants, fixed film reactors, or other
appropriate small scale treatment process. Disposal methods can be surface land application,
subsurface land disposal or stream discharge. Because information on transportation and treatment
options is available through various other fact sheets, this fact sheet examines individual septic
tanks followed by small diameter gravity sewers and subsurface disposal at a given site. This
system is representative of the available cluster system options.
COMMON MODIFICATIONS
Small diameter gravity sewer systems cannot always provide service to all houses. An effluent
pump is often required to lift the septic tank effluent to the sewer lines. Pumps are usually set
in a separate pumping chamber. The common soil absorption system can be modified by dividing the
field into two or three fields so that resting can be provided for the drainfield.
TECHNOLOGY STATUS
Small diameter sewers have been used extensively in South Australia with good results since
1962 (27). Subsurface disposal systems are fully developed technologically, although multi-family
application is a more recent development.
APPLICATIONS
Cluster systems can be used to avoid site limitations such as poor soils or shallow bedrock at
individual sites. Developed areas that are isolated from the remainder of a community are candi-
dates for cluster systems, especially if the isolated development has small lot sizes not appro-
priate to on-site treatment systems.
LIMITATIONS
Unlike individual on-site systems, cluster systems require management to ensure that the
treatment and disposal process is operating properly and that septic tanks are pumped regularly.
Solids overflow from septic tanks contributes to clogging of small diameter gravity lines and
increases the solids loading on the soil absorption system.
TYPICAL EQUIPMENT/NUMBER OF MANUFACTURERS
Small diameter pipe and materials for subsurface disposal systems are locally supplied.
PERFORMANCE
Small diameter gravity sewers have performed well, based on the limited amount of data avail-
able (27). Large subsurface disposal systems have also functioned satisfactorily in multi-family
applications when properly designed, located, constructed, and maintained.
DESIGN CONSIDERATIONS
Small diameter collection sewers should be a minimum of 4" in diameter to facilitate cleaning
equipment. The 4" sewers can be laid on a minimum 0.67% grade based on a minimum velocity of 1.5
FPS at half-pipe capacity. Clean-outs should be provided wherever an individual connection joins a
sewer line or every 100 feet, whichever is less. Infiltration/inflow is usually less with small
diameter lines than with conventional lines. Subsurface disposal systems should follow basic design
criteria for individual systems with particular emphasis placed on the distribution of effluent to
the soil (gravity dosing or pressure distribution is recommended). Monitoring wells are required
to (1) monitor the performance of the system, and (2) protect groundwater resources by monitoring
the level of contaminants reaching various groundwater levels. Hydrogeologic studies on potential
sites should be conducted prior to construction of a common soil absorption system. Delegation of
the management authority is necessary to ensure continued operation.
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CLUSTER SYSTEMS
October 1980
FACT SHEET 4.2
RELIABILITY
Excellent reliability can be expected for small diameter collection lines because of their
dependence on gravity and their corrosion-free construction. An increase in pumps throughout the
system would reduce the overall reliability. Gravity dosed soil absorption systems have a high
degree of reliability. System reliability is increased by dividing the drainfield into three
separate fields each designed to treat 50% of the design flow. The field that is resting acts as an
emergency backup.
ENVIRONMENTAL IMPACT
Small diameter sewers limit the increased land development impact usually associated with
sewers because of their smaller capacity. Construction impacts may also be less than for conven-
tional sewers if smaller trenches, fewer manholes, and faster construction are required.
Subsurface disposal systems can provide sufficient filtration, adsorption, and micorbial
degradation of harmful constituents in household effluent. System failures, however, can occur and
are related to site limitations or to improper installation, operation, or maintenance. Adverse
environmental effects attributed to failures of subsurface disposal systems generally involve the
contamination of ground or surface waters. This contamination may then result in public health
hazards if drinking water is affected, or in accelerated eutrophication if excessive amounts of
nutrients are delivered to lakes or streams.
Mitigation and avoidance of adverse environmental impacts depend on information regarding
site-specific conditions that led to system failures in a community, and the use of this infor-
mation to select repairs and replacement systems and to design new systems.
REFERENCES
27, 94, 18, 49, 85, 77, 71, 44.
DIAGRAM
CLUSTER SYSTEM USING SMALL DIAMETER COLLECTION
SEWERS AND COMMON SOIL ABSORPTION SYSTEM
SOIL
ABSORPTION
SYSTEM
SMALL DIAMETER
COLLECTION SEWER
DOSING TANK
OR PUMP STATION
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CLUSTER SYSTEMS FACT SHEET 4.2
October 1980
ENERGY NOTES
The only energy consuming components of this type of cluster system are pumps for transporting
septic tank effluent when gravity lines are not feasible and for distributing the effluent over the
drainfield. Total energy required would depend on the design flow and number of pumps required in
the collection system.
COSTS
1980 dollars: ENR Index - 3260.
The following construction costs for small diameter collection lines are based on a design
population of 500 and a length of sewer per capita of 35.3 ft. in an area of ideal topography and
new development (44).
COMPONENT ESTIMATED COST
($/HOUSEHOLD)
Building Sewer and Septic Tank 528
Mainline Construction Cost 1854
(4 gravity sewer)
Ancillary Cost 373
On-Iot (House Connection) 370
TOTAL CONSTRUCTION COST PER HOUSEHOLD 3125
The following construction costs for subsurface disposal systems assume three fields, each
designed to accept 50% of the flow. A trench design using a percolation rate of 45 rapi is assumed
with a three-foot-wide trench. Costs for hydrogeologic studies are not included. Monitoring wells
are included in the estimates.
FLOW(gpd) CONSTRUCTION COST($)
2,000 26,260
10,000 93,036
20,000 171,375
30,000 267,985
50,000 458,456
OPERATION AND MAINTENANCE
0 & M costs for small diameter collection sewers are estimated to be $500-600/mile/year (18).
0 & M associated with gravity-dosed subsurface disposal system are related to checking the system
periodically and taking samples from the monitoring wells. These costs are estimated to be $100 per
monitoring well per year.
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REFERENCES
1. Advanced Drainage Systems. 1979. SB2: The new gravel-less, large diameter leach bed tubing from
ADS. Columbus OH.
2. Association of Monterey Bay Area Governments. 1977. Septic system pollution control alterna-
tives. Draft. Monterey CA.
3. Baker, Larry K. 1980. The impact of water conservation on on-site wastewater management. Wea-
therby Associates, Inc. Jackson CA.
4. Beehler, G. R. and J. A. Moore. University of Minnesota. 1979. A study of the characteristics
and pollution potential of land spread domestic septage on groundwater quality. University
of Minnesota, Agricultural Engineering Department. St. Paul MN.
5. Beer, C. E., D. L. 0. Smith, D. D. Effert, and R. J. Smith. 1978. Analysis and performance of a
sewage osmosis system. Proceedings of the Second National Home Sewage Treatment Symposium,
Chicago Illinois. 12-13 December 1977. ASAE Publication 5-77. St. Joseph MI. pp!93-201.
6. Bouma, J. , J. C. Converse, R. J. Otis, W. G. Walker, and W'. Z. Zieball. 1975. A mound system for
on-site disposal of septic tank effluent in slowly permeable soils with seasonally perched
water tables. Journal of Environmental Quality 4(3):382-388.
7. Bowker, R. P. G. and S. W. Hathaway. 1978. Alternatives for the treatment and disposal of resi-
duals from on-site wastewater systems. Prepared for U.S. EPA Training Seminar on Wastewater
Alternatives for Small Communities. U.S. EPA, Municipal ERL, Cincinnati OH
8. Boyle, W. C. and R. J. Otis. 1978, reprinted 1979. On-site treatment. Prepared for U.S. EPA
Technology Transfer Seminars on Wastewater Treatment Facilities for Small Communities. U.S.
EPA, Environmental Research Information Center, Cincinnati OH.
9. Brandes, M. , N. A. Chowdhry, and W. W. Cheng. 1974. Experimental study on removal of pollutants
from domestic sewage by underdrained soil filters. Proceedings of the National Home Sewage
Disposal Symposium, Chicago Illinois. 9-10 December 1974. ASAE Publication Proc. 175. St.
Joseph MI. pp29-36.
10. Brown and Caldwell. 1977. Individual waste disposal management program. Lane County, Oregon.
208 Project. Lane Council of Governments, Eugene OR.
11. Brown, D. V. and R. K. White. 1977. Septage disposal alternatives in rural areas. Extension
Bulletin 624, Cooperative Extension Service, Ohio State University.
12. California Department of Water Resources. 1978. A pilot water conservation program. Bulletin
191. Main Report, Appendix G (Device Testing), and Appendix H (Device Selection).
Sacramento CA.
13. Chan, Man L., Jack Edwards, Marc Roberts, Robin Stedinger, and Leslie Wilson. 1976. Household
water conservation and wastewater flow reduction. NTIS PB-265 578. U.S. EPA, Office of
Water Planning & Standards, Washington DC.
14. Chestnut, Tom. 1977. Design and construction costs of sand filter installations in central
Illinois. Proceedings, 2nd Annual Illinois Private Sewage Disposal Symposium. Champaign,
Illinois. 17-19 January 1977. Illinois Department of Public Health and University of
Illinois. pp28-38
15. CMS Equipment Ltd. 1980. Rotodisk: Simple sewage treatment system. Mississauga, Ontario
Canada.
16. Cohen, Sheldon and Harold Wallman. 1974. Demonstration of waste flow reduction from households.
NTIS PB-236 904. General Dynamics Corp., for U.S. EPA, National Environmental Research
Center, Cincinnati OH.
17. Cole, Charles A. 1975. Impact of home water saving devices on collection systems and waste
treatment. Proceedings, Conference on Water Conservation and Sewage Flow Reduction with
Water-Saving Devices. Information Report No. 74, Pennsylvania State University, Institute
for Research on Land and Water Resources, University Park PA. pp47-55.
18. Connecticut Areawide Waste Treatment Management Planning Board. 1979. Alternatives to sewers: A
summary of innovative and alternative systems. Middletown CT.
I-A-70
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19,. Converse, J. C., J. L. Anderson, W. A, Ziebell, and J. Bouma. 1974. Pressure distribution to
improve soil absorption systems. Proceedings of the National Home Sewage Disposal
Symposium, Chicago, Illinois. 9-10 December 1974. ASAE Publication Proc. 1975. St. Joseph
MI. pp!04-115.
20. Converse, J. C., B. L. Carlile, and G. W. Petersen. 1978. Mounds for the treatment and disposal
of septic tank effluent. Proceedings of the Second National Home Sewage Treatment
Symposium, Chicago, Illinois. 12-13 December 1977. ASAE Publication 5-77. St. Joseph MI.
pplOO-120.
21. Cook, Robert E. Undated. Opportunities for further efficiency improvement in domestic water
heaters. A. D. Smith Corp., Kankakee IL.
22. Coolbroth, Frank. 1977. Sewage osmosis concept to eliminate groundwater pollution. Proceed-
ings, 2nd Annual Illinois Private Sewage Disposal Symposium. Champaign, Illinois, 17-19
January 1977. Illinois Department of Public Health and University of Illinois. pp97-102.
23. Cooper, I. A. and J. W. Rezek. 1977. Septage treatment and disposal. Prepared for the U.S. EPA
Technology Transfer. Seminar Program on Small Wastewater Treatment Systems. Rezek, Henry,
Meisenheimer and Gende, Inc.
24. Dewberry Nealon and Davis. 1980. Residential wastewater systems. National Association of Home-
builders, Washington DC.
25. Feige, W. A., E. T. Oppelt, and J. F. Kreissl. 1975. An alternative septage treatment method:
lime stabilization/sand-bed dewatering. NTIS PB-245 816. U.S. EPA, Municipal Environmental
Research Lab., Cincinnati OH.
26. Fetter, C. W., W. E. Sloey, and F. L. Spangler. 1976. Potential replacement of septic tank drain
fields by artificial marsh wastewater treatment systems. Groundwater 14(6).
27. Fey, Robert T. 1979. Practical application of small-scale wastewater system design, Westboro,
Wisconsin. Carl C. Crane, Inc., Madison WI.
28. Flack, J. Ernest, Wade P. Weakley, and Duane W. Hill. 1977. Achieving urban water Conservation:
A handbook. Completion Report No. 80. Colordo State University, Environmental Resources
Center, Ft. Collins CO.
29. Franko, William. 1974. Above ground sewage disposal in rural Saskatchewan. Proceedings of the
National Home Sewage Disposal Symposium. Chicago IL. 9-10 December 1974. ASAE Pub. Proc.
175. St. Joseph MI. pp!63-l67.
30. Froth & Van Dyke & Associates, Inc. 1973. Interim report on the bio-surf home wastewater treat-
ment plant installed at the Joseph N. Linssen residence. Green Bay WI.
31. Goldstien, Steven N. and Walter J. Moberg, Jr. 1973. Wastewater treatment systems for rural
communities. Commission on Rural Water, Washington DC.
32. Great Lakes-Upper Mississippi River Board of State Sanitary Engineers. 1980. Recommended stan-
dards for individual sewage systems. Health Education Service, Albany NY.
33. Hansel, Michael J. and Roger E. Machmeier. 1980. On-site wastewater treatment on problem soils.
Journal of Water Pollution Control Federation 52(3):548-558.
34. Harkin, John M., Charles J. Fitzgerald, Colin P. Duffy, and David G. Krou. 1979. Evaluation of
mound systems for purification of septic tank effluent. Technical Report, Wisconsin 79-05.
University of Wisconsin, Water Resources Center, Madison WI.
35. Harrison. 1971. Jet-0-Matic recirculating chemical toilets. Equipment Development and Test
Report 2300-5. U.S. Forest Service, Equipment Development Center, San Dimas CA.
36. Hines, Michael and R. E. Favreau. 1974. Recirculating sand filter: An alternative to tradi-
tional sewage absorption systems. Proceedings of the National Home Sewage Disposal
Symposium. Chicago Illinois. 9-10 December 1974. ASAE Publications Proc. 175. St. Joseph
MI.
I-A-71
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37. Hines, M. W. , E. R. Bennett, and J. R. Hoehne. 1978. Alternative Systems for Effluent Treatment
and Disposal. Proceedings of the Second National Home Sewage Treatment Symposium, Chicago
Illinois. 12-13 December 1977. ASAE Publication 5-77. St. Joseph MI.
38. Hoover, Michael T. 1979. Inventory and evaluation of elevated sand mound sewage disposal systems
in Pennsylvania. Master's Thesis. NTIS PB80-15807. Pennsylvania State University,
University Park PA.
39. Ingham, Alan T. 1980. Guidelines for mound systems. California State Water Resources Control
Board, Sacramento CA.
40. Institute of Water Resources, University of Alaska. The characteristics and ultimate disposal of
waste septic tank sludge. Report No. IWR-56. University of Alaska, Fairbanks AL.
41. Jewell, William J. Design guidelines for septic tank sludge treatment and disposal. Progress in
Water Technology 7(2):191-205.
42. Kadlec, Robert H. , Donald L. Tilton, and Benedict R. Schwegler. 1979. Wetlands for tertiary
treatment: A three-year summary of pilot scale operations at Houghton Lake. University of
Michigan, Wetland Ecosystem Research Group, Ann Arbor MI.
43. Konen, Thomas P., and Raymong DeYoung. 1975. An investigation of the performance and the effects
of reduced volume water closets on sanitary drainage, sewers, and sewage treatment plants."
Proceedings, Conference on Water Conservation and Sewage Flow Reduction with Water-Saving
Devices. Information Report No. 74. Pennsylvania State University, Institute for Research
on Land and Water Resources, University Park PA. pp!55-171.
44. Kreissl, James F., Robert Smith, and James A. Heidman. 1978. The cost of small community waste-
water alternatives. Prepared for U.S. EPA Training Seminar on Wastewater Alternatives for
Small Communities.
45. Laak, Rein. 1980. Wastewater engineering design for unsewered areas. Ann Arbor Science Pub-
lishers, Ann Arbor MI.
46. Local Government Research Corp. 1974, reprinted 1975. Technical manual for sewage enforcement
officers. Pennsylvania Department of Environmental Resources, Harrisburg PA.
47. Lombardo, Pio. 1977. Septage composting. Compost Science. 18(6):12-14
48. Machmeier, Roger E. 1979. Town and country sewage treatment. Revised Edition. University of
Minnesota, Agricultural Extension Service, St. Paul MN.
49. Machmeier, Roger E. and Michael J. Hansel. 1980. Home sewage treatment workshop. University of
Minnesota and Minnesota Pollution Control Agency, St. Paul MN.
50. Microphor, Inc. 1976. The Microphor low flush toilet. Willits CA.
51. Middlebrooks, E. Joe, Norman B. Jones, James H. Reynolds, and Michael F. Torpy. 1978. Lagoon
information source book. Ann Arbor Science. Ann Arbor MI.
52. Miller, Scott A. Undated. Two quart low flush toilets and the septic tank. Ukiah CA.
53. Milne, Murray. 1976. Residential water conservation. Report No. 35. University of California,
Water Resources Center, Davis CA.
54. Minuse Enviro-Systems. Undated. Minuse MU-2000 shower (Pat. Pend.): Description of products
operation. Mokelumne Hill CA.
55. Minuse Enviro-Systems. 1980. The Minuse MU-2000 Shower. Mikelumne Hill CA.
56. Monogram Industries, Inc. 1979. Monogram Sanitation Systems. Long Beach CA.
57. Muller, John G. 1974. Residential water heating. Memorandum to Mike Power. Federal Energy
Administration, Washington DC.
58. Muller, John G. 1979. Showers. Memorandum to Bob Lane. U.S. Department of Energy, Washington
DC.
I-A-72
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59. National Environmental Health Assn. 1979. A 1979 state of the art manual of on-site wastewater
management. Denver CO.
60. National SSR, Inc. 1979. Septic solids retainer (Product Description). General Engineering Co.
Frederick MD.
61. Nelson, John 0. 1977. North Marin's little compendium of water saving ideas. North Marin County
Water District, Novato CA.
62. North Carolina Department of Human Resources. 1977. Site evaluation guide for ground absorption
sewage disposal systems of 3,000 gallons or less design capacity (Application of IONCAC.
1900 to the soils of NC). Division of Health Services, Sanitary Engineering Section, Raleigh
NC.
63. Otis, R. J., and D. E. Stewart. 1976. Alternative wastewater facilities for small unsewered
communities in rural America. University of Wisconsin, Small Scale Waste Management Project,
Madison WI.
64. Otis, R. J. , G. D. Plews, and D. J. Patterson. 1978. Design of conventional soil absorption
trenches and beds. Proceedings of the Second National Home Sewage Treatment Symposium,
Chicago, Illinois. 12-13 December 1977. ASAE Publication 5-77. St. Joseph MI. pp86-99.
65. Otis, R. J., J. C. Converse, B. L. Carlile, J. E. Witty. 1978. Effluent distribution. Pro-
ceedings of the Second National Home Sewage Treatment Symposium, Chicago Illinois. 12-13
December 1977. ASAE Publication 5-77. St. Joseph MI. pp61-85.
66. Petersen, G. W., and D. D. Fritton. 1979. Evaluation of mound systems for renovation of septic
tank effluent. Pennsylvania State University, Institute for Research on Land and Water
Resources, University Park PA.
67. Ralph, David and Dale Vanderholm. 1978. Design, construction and costs of recirculating sand
filters. Proceedings, Third Annual Illinois Private Sewage Disposal Symposium, Illinois
Department of Public Health & University of Illinois. Champaign, Illinois, 13-15 February
1978. pp37-51.
68. Reynolds, James H. , E. J. Middlebrooks, and C. H. Middlebrooks. 1978. Lagoons for small waste-
water flows. Individual on-site wastewater systems: Proceedings of the 5th National
Conference, 1978. Ann Arbor Science Publishers, Ann Arbor MI.
69. Rodiek, Roger K. 1977. Some watershed analysis tools available for lake management. MS Thesis,
University of Michigan.
70. Sack and Phillips. 1973. Evaluation of the bio-disc treatment process for summer camp applica-
tion. NTIS PB-225 126. U.S. EPA, Office of Research & Development, Washington DC.
71. a. Schmidt, Curtis J. et al. 1979. Manual for on-site wastewater treatment and disposal sys-
tems. Draft. Contract No. 68-01-4904, U.S. EPA Washington DC.
b. Schmidt, Curtis J. et al. 1980. Design manual: On-site wastewater treatment and disposal
systems. Final. U.S. EPA, Washington DC.
72. SCS Engineers. 1979. Rural wastewater management guidance manual: A guide to alternative waste-
water systems for rural and small communities. California Water Resources Control Board,
Sacramento CA.
73. Sharpe, William E. 1979. Selection of water conservation devices for installation in new or
existing dwellings. Proceedings, National Conference on Water Conservation and Municipal
Wastewater Flow Reduction, Chicago Illinois. 28-29 November 1978. EPA-430/9-79-015. U.S.
EPA, Office of Water Program Operations, Washington DC.
74. Sharpe, William E. and Charles A. Cole. 1977. The impact of water saving water closets on build-
ing drains and sewers. Plumbing Engineer, November-December, pp20-21, 60.
75. Sheldon, W. H. 1964. Septic tank drainage systems. Research Report 10. Michigan State Univer-
sity Agricultural Experiment Station, E. Lansing MI.
76. Shepard, James E. 1974. Guide for the successful design of small sewage disposal systems to
enable compliance with the statutory requirements of RSA 149-E. New Hampshire Water Supply &
Pollution Control Commission, Concord MA.
I-A-73
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77. Sherwood Specialities Inc. Undated. Kovarik-Sherwood anarobe sewage transport and primary treat-
ment system. Rochester NY.
78. Siegrist, Robert L. 1980. Residential waste flow reduction with low-flush toilet fixtures. Uni-
versity of Wisconsin, Small Scale Waste Management Project, Madison WI.
79. Stanly Consultants. 1977. Wastewater treatment by marsh application. Work report for the New
Orleans-Baton Rouge , Louisiana Metropolitan Area. Water Resources Study. Submitted to the
Department of the Army, New Orleans District Corps of Engineers. Atlanta, GA-.
80. Stoner, Carol Hupping, ed. 1977. Goodbye to the flush toilet: Water-saving alternatives to
cesspools, septic tanks, and sewers. Rodale Press. Emmaus PA.
81. Stowell, Rich, Robert Ludwig, John Colt, and George Tchobanoglous. 1980. Toward the rational
design of aquatic treatment systems. Presented at the American Society of Civil Engineers
spring convention, Portland Oregon, 14-18 April 1980. University of California, Department
of Civil Engineering, Davis CA.
82. Tchobanoglous, George. 1975. Wastewater treatment for small communities. Proceedings of a rural
environmental engineering conference. University Press of New England, Hanover NH.
83. Tchobanoglous, George and Gordon L. Culp. 1979. Wetland systems for Wastewater treatment: An
engineering asessment (Draft). U.S. EPA, Washington DC.
84. Tchobanoglous, George. John E. Colt, and Ronald W. Crites. 1980. Energy and Resource Consumption
in Land and Aquatic Treatment Systems. Proceedings of the U.S. D.O.E. Energy Optimization
of Water and Wastewater Management for Municipal and Industrial Applications Conference. New
Orleans, Louisiana, 10-13 December 1979. Argonne National Laboratory, Argonne IL.
85. Triangle J. Council of Governments. 1978. Individual non-urban wastewater treatment and manage-
ment alternatives, Task B: Summary of alternative on-site wastewater treatment and disposal
methods, Region J, North Carolina. Research Triangle Park NC.
86. U.S. EPA. 1977. Alternatives for small wastewater treatment systems. Vol. 1: On-site disposal/
septage treatment and disposal. Vol. 2: Pressure sewers/vacuum sewers. Vol. 3: Cost-
effectiveness analysis. Technology Transfer, Cincinnati OH.
87. U.S. EPA. 1977. Feasibility of treating septic tank waste by activated sludge. EPA-600/2-77-141.
88. U.S. EPA. 1977. Process design manual, wastewater treatment facilities for sewered small com-
munities. EPA-625/1-77-009. Technology Transfer. Cincinnati OH.
89. U.S. EPA. 1977. Treatment and disposal of wastes pumped from septic tanks. EPA-600/2-77-198.
Storrs Agricultural Experiment Station, Connecticut.
90. U.S. EPA. 1978. Pilot scale evaluations of septage treatment alternatives. EPA-600/2-78-164.
91. U.S. EPA. 1978. Design seminars handout: Small wastewater treatment facilities. Technology
Transfer.
92. U.S. EPA. 1979. Design seminar handout: Small wastewater treatment facilities. Technology
Transfer, Cincinnati OH.
93. U.S. EPA. 1979. Monitoring septage addition to wastewater treatment plants. Volume 1: Addition
to the liquid stream. EPA-600/2-79-132.
94. U.S. EPA. 1980. Innovative and alternative technology assessment manual. EPA-430/9-78-009.
Office of Water Program Operations, Washington DC.
95. U.S. EPA and WAPORA, Inc. 1979. Draft environmental impact statement, alternative waste treatment
systems for rural lake projects. Case Study No. 1: Crystal Lake Area Sewage Disposal
Authority, Benzie County, Michigan. Region 5, Chicago IL.
96. University of Wisconsin. 1978. Small Scale Waste Management Project. Management of small waste
flows. NTIS PB-286 560. For U.S. EPA, Municipal ERL, Cincinnati OH.
I-A-74
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97. University of Wisconsin. 1978. Small scale waste management project. Management of small waste
flows, Appendix D: Institutional regulatory aspects. Grant No. R-802874. U.S. EPA,
Municipal ERL, Cincinnati OH.
98. Vermont Water Resources Research Center. 1978a. Septage management in Vermont: Case studies and
a statewide strategy. Project Report No. 4. Burlington VT.
99. Vermont Water Resources Research Center. 1978b. Technical alternatives for septage treatment and
disposal in Vermont. Project Report No. 2. Burlington VT.
100. Vivona, M. A., and W. Herzing. 1980. The use of septage lagoons in New England. Sludge, March-
April.
101. Warshall, Peter. 1979. Septic tank practices: A guide to the conservation and reuse of house-
hold wastewater. Anchor Press/Doubleday, Garden City NY.
Illustration on Fact Sheet 2.2, from the book, Septic Tank Practices by Peter Warshall, Copyright©
1979 by Peter Warshall. Reprinted by permission of Anchor Press/Doubleday Company, Inc.
102. Water & Sewage Works. 1980. Small RBCs logging hours in Yugoslavia, 127(8):42-44.
103. Water & Wastewater Equipment Manufacturers Assn. 1980. Membership directory, 1980-81. McLean
VA.
104. Weigand, Richard G. 1979. Alternative on-site sewage systems in Wood County, West Virginia
Field Survey. Proceedings, 4th Annual Illinois Private Sewage Disposal Symposium. February
26-28, 1979, Illinois Department of Public Health & University of Illinois. Champaign IL.
pp43-65.
105. Weigand, Richard G. 1979b. Performance of alternative on-site sewage systems in Wood County,
West Virginia. Journal of Environmental Health 42(3):133-138.
106. Wisconsin Department of Industry, Labor & Human Relations. 1980. Emergency rules and proposed
permanent rules relating to alternative sewage systems. Madison WI.
107. Witz, Richard I. 1974. Twenty-five years with the Nodak Waste Disposal System. Proceedings of
the National Home Sewage Disposal Symposium, Chicago IL. 9-10 December 1974. ASAE Pub.
Proc. 175. St. Joseph MI. ppl68-174.
108. Wooding, N. Henry. Undated. Alternate methods of effluent disposal for on-lot home sewage sys-
tems. Special circular 214. Pennsylvania State University, Cooperative Extension Service,
University Park PA.
109. Fluid Dynamics Co. 1980. Automatic dosing siphons for small disposal plants. Boulder CO.
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CHAPTER II
EVALUATION AND DESIGN METHODOLOGIES
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A. WATER QUALITY IMPACTS OF ON-SITE SYSTEMS
The purpose of this report is to review the available literature regard-
ing on-site sytems in order to evaluate their effects on ground and surface
water quality. Whenever possible, particular emphasis is placed on the
literature that pertains to rural lake communities in the Region V states.
Relatively few field investigations have been conducted in these areas; thus,
these results are supplemented with research from other geographical areas and
from laboratory studies.
Septic tank systems are used by approximately 25% of the U.S. population
(Scalf et al., 1977). Wastewater from households can contain pathogenic
bacteria and viruses, nutrients, and other chemical pollutants. In a success-
fully functioning system, the surrounding soil will absorb and purify most
wastes. The goal of the system is to remove pathogens and to reduce the
concentrations of the other wastewater constituents so that no adverse effects
occur from consumption of the receiving water or from addition of the effluent
to ground or surface waters.
In many cases, given proper design, installation, and operation, on-site
systems will perform satisfactorily; however, failures do occur and can result
in the contamination of local water resources. Two basic types of septic tank
failures are recognized. One type of failure generally is caused by soil
clogging, which severely restricts or even eliminates the wastewater flow into
the absorption field. This is manifested either by surface seepage of
partially treated effluent above the drainfield or by wastewater backing up
into the plumbing fixtures in the house. In the first case, the seepage can
create .standing pools of effluent that can cause odors, attract insects, and
pose health risks to playing children or that can be carried with surface
runoff into nearby domestic wells, lakes, or streams. The second type of
failure, which is potentially more serious and less obvious, occurs when
septic tank effluent reaches the groundwater without sufficient treatment.
This, too, can result in contamination of private water supplies or nearby
surface waters fed by groundwater sources.
The contamination of ground or surface waters from domestic wastewater
may create both public health and environmental hazards. Outbreaks of water-
borne disease have been traced to microbial or viral contamination of ground-
water by malfunctioning septic tanks. It would seem likely that inadequately
treated wastewater that surfaces above the drainfield could cause disease from
direct contact or from vector transmission, although no reports of such
disease outbreaks were encountered in the literature review. In addition,
nitrogen, in the form of nitrate, has been linked with cases of methemoglo-
binemia in infants. From the environmental standpoint, accelerated eutrophi-
cation can result if excessive nutrient concentrations reach surface waters.
Lake shorelines are particularly sensitive; in some lakes, growth of aquatic
plants in shallow waters has been blamed on emerging groundwater plumes con-
taining septic tank effluent along the lakeshore. Other chemical constituents
in household wastewater pose potential health and environmental problems if
they are not degraded or purified in the soil before reaching receiving
waters.
The available literature is discussed in this report primarily in terms
of the water quality impacts that can result from the discharge of pathogens
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and nutrients into soil. Other chemical compounds that possibly could be
present in domestic wastewater are discussed in less detail.
The studies reviewed indicate that under some conditions the potential
exists for the entry, survival, and migration of these pathogens and pol-
lutants in aquifers and surface waters. No one has attempted to estimate the
probability of the occurrence of adverse water quality impacts from the use of
conventional on-site systems. This is undoubtedly a result of the many con-
trolling factors that are involved. Generally, such things as site-specific
conditions, hydrogeology factors, meteorologic considerations, system main-
tenance, and population or system densities work alone or in combination to
bring about adverse effects.
Standard design and installation codes are implemented to protect human
health and the environment. It is unreasonable, however, to expect that the
application of one set of design factors throughout a wide area would prevent
contamination of waters in all cases. The literature on the subject documents
individual cases where problems have arisen without emphasizing that many
systems operate successfully without harm to public health and the environ-
ment.
The interaction of septic tank effluent and the underlying soil is com-
plex. Proper performance of conventional on-site wastewater disposal systems
depends on the inherent ability of the soil to transmit and renovate the
wastewater. This in turn is dependent on many other factors, some of which
are discussed in the following sections of this report. The wastewater
absorption capabilities of soils are described in more depth elsewhere (Bouma,
1975; Miller and Wolf, 1975; Tyler et al., 1978; University of Wisconsin,
1978).
Prolonged infiltration of septic tank effluent into a soil absorption
field will cause the development of a crust with a low permeability at the
effluent infiltrative surface. The formation of this "clogging zone" is a
result of physical, biological, and chemical processes. The soil type is
important. Soil is composed of many particles of different shapes and sizes
that are interconnected by pores or capillaries. Depending on the soil mois-
ture content, these spaces are filled with varying proportions of air and
liquid and it is through these capillaries that the effluent flows. Most
wastewater solids settle in the bottom of the septic tank but some flow out
with the effluent into the seepage bed and contribute to the clogging of
capillaries at the soil-effluent interface. The sewage bacteria in the
wastewater merge with the soil bacteria and multiply rapidly at this surface,
where they are provided with a constant source of nutrients. The resultant
biomass further restricts flow through the capillaries and is effective in
degrading organic wastes in the effluent.
These and other processes contribute to the clogging phenomenon. Al-
though the rate of flow into the soil is reduced, the clogging mat also
enhances the purification of the effluent by increasing its retention time.
As long as there is periodic drying, the aerobic environment at the soil-
effluent loading surface should be maintained, as should the infiltrative
capacity. Both of these conditions are essential for the successful operation
of the on-site system and contribute greatly to the renovation of typical
household wastewater constituents (Harkin et al., 1975).
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1. FATE OF MICROORGANISMS IN DISCHARGE FROM ON-SITE SYSTEMS
From the public health standpoint, concern exists about the potential for
movement of disease-causing bacteria and viruses through the soil below on-
site disposal systems into groundwater supplies and over the soil to surface
waters. The potential health hazard from pathogenic organisms will depend on
their presence in the wastewater and in drinking water, the numbers that are
present, and the accessibility of the pathogens for subsequent human consump-
tion. These factors are influenced further by the general status of the
pathogen population, the pathogen survival rates outside the host, and the
movement of the organisms within the environment (Miller and Wolf, 1975).
Bacteria normally are present in the human intestinal tract. Many of
these are the same types of bacteria that are naturally present in soils and
water. Together, the sewage bacteria and native soil bacteria are capable of
reducing complex, organic solids into more simple and soluble compounds. In
this respect, bacteria perform an essential step in the wastewater treatment
process.
In addition to the normal intestinal bacteria, however, domestic waste-
water also may contain pathogens, if individuals in the households are in-
fected and are shedding pathogens with feces. Detection of all types of
pathogenic bacteria and viruses is difficult, so tracer organisms are often
used as indicators of fecal pollution. A low density of indicator organisms
implies an absence of pathogens. Two frequently used indicators are fecal
coliform bacteria and fecal streptococci because they:
• are present in high numbers in feces of humans and other warm-blooded
animals;
• can survive outside the body for long periods of time;
• are detectable quantitatively with available methods; and
• are found in relatively higher numbers than the pathogens, so their
detection is more likely (University of Wisconsin, 1978).
The presence of pathogens in drinking water, even if found in relatively
small numbers, is considered hazardous because the minimum infectious dose has
not been established accurately for all pathogens (Pipes, 1978). Available
information suggests that a relatively large number of enteric bacteria, but
only a few enteric viruses, are needed to bring about a clinical disease
(Cooper and Golueke, 1977). There are a number of diseases that are of fecal
origin. Bacteria and viruses can cause intestinal or enteric diseases such as
food poisoning, typhoid fever, cholera, hepatitis, and other gastroenteric and
diarrheal diseases (Craun, 1975; Pipes, 1978).
Many wastewater-borne pathogens have been implicated as causative agents
in outbreaks of enteric diseases. Almost half of the 192 outbreaks of water-
borne disease that affected 36,757 people in the U.S. between 1971 and 1977
were attributed to the use of untreated or inadequately treated groundwater
(Craun, 1979a). Twelve percent of the outbreaks occurred in individual
systems and affected an average of ten persons per outbreak. It is likely
that the published figures understate the actual incidence, for several
II-A-3
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reasons. Generally, waterborne disease outbreaks are reported only when the
disease is severe and there are a number of common source cases. Also,
sporadic cases go unnoticed or cannot be ascribed categorically to the water-
borne route. Finally, contamination is often temporary and may be cleared up
before a water sample is taken so that no agent is identified (Pipes, 1978).
Overflow from septic tanks and cesspools was responsible for 42% of the
disease outbreaks that occurred in nonmunicipal systems during the period from
1946 to 1977 (Keswick and Gerba, 1980). Thus, the public health concern re-
garding on-site systems appears justified. On the other hand, well-function-
ing soil absorption fields have been shown to be very efficient in removing
disease-causing microorganisms. Many system failures that result in microbial
contamination of nearby waters can be attributed to improper design, installa-
tion, or operation of the systems. Numerous laboratory and field studies have
been conducted to determine which factors affect the removal, survival, and
migration of pathogens in soil and groundwater systems. The aim of these
studies is to avoid future septic tank failures and to minimize potential
health hazards. Many of these investigations are reviewed in this section.
a. Bacterial Quality of Septic Tank Effluent
While the level of treatment in a septic tank is significant, the
effluent still contains extremely high numbers of bacteria. Bacteriological
analyses were performed on effluent samples from five septic tank systems
(Ziebell et al., 1975a). The bacterial quality data are summarized in Table
II-A-1. For comparison, the current fecal coliform standard specifies that
for discharge of effluents to surface waters the concentration cannot exceed
200 fecal coliform/100 ml. Although there are no comparable standards for
groundwater discharge, this provides an indication of the degree to which
septic tank effluent must be purified in the soil before reaching groundwater
that may be used for human consumption without pretreatment. To minimize the
risk of the transmission of enteric disease, therefore, the soil must be
capable of removing the pathogenic bacteria that may enter the soil in septic
tank effluents.
TABLE II-A-1. REPRESENTATIVE BACTERIOLOGICAL QUALITY OF SEPTIC TANK EFFLUENT
(Ziebell et al., 1975a)
Bacteria/100 ml
Geometric
mean
95% Confidence
interval
Number
of samples
Total coliforms 34 x 105 26 x 105-44 x 105 91
Fecal coliforms 42 x 104 29 x 104-62 x 104 94
Fecal streptococci 38 x 102 20 x 102-72 x 102 97
P. Aeruginosa 10 x 103 1.9 x 103-54 x 103 13
Total bacteria 34 x 107 25 x 107-48 x 107 88
II-A-4
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b. Bacterial Removal
Soils have a tremendous capacity for the removal of bacteria from domes-
tic wastewater. As noted, however, effluents from septic tanks contain large
numbers of bacteria. These bacteria are removed primarily by straining, sedi-
mentation, entrapment, and adsorption (McGaughey and Krone, 1967). Most bac-
teria are filtered out of the percolating effluent at the clogging zone, which
generally occurs within the first six inches. Romero (1970) further attri-
butes the rapid removal of wastewater bacteria to adverse conditions in the
soil: abrupt temperature changes; oxygenation and nitrification; and die-off
as a result of competition with native soil bacteria.
Many field and laboratory studies have been conducted to examine the
efficiency of soil for bacteria removal and to determine the parameters that
affect this efficiency. Factors that are considered important include soil
type, temperature, pH, bacterial absorption to soil and soil clogging materi-
als, soil moisture and nutrient content, and bacterial antagonisms (Gerba et
al., 1975). The degree of saturation also is important. Unsaturated flow
increases effluent and soil contact time, which enhances purification
(University of Wisconsin, 1978). Most of these same factors also affect
bacterial survival and movement.
As part of the Small Scale Waste Management Project at the University of
Wisconsin-Madison, Ziebell et al. (1975b) conducted a series of soil column
experiments to evaluate bacteria removal from septic tank effluent by dif-
ferent soil types under varying temperature and flow regimes. Columns of 2
feet (60 cm) in length were filled with either loamy sand or silt loam. Fewer
bacteria passed through the sand column that was loaded with 5 cm/day of
septic tank effluent than through the one that received a lOcm/day dose. Once
a clogging zone developed at the infiltrative surface, removal rates were
improved further. Soil temperature was also found in part to affect bacterial
removal rates, by inducing early soil clogging at low temperatures. At 25° C,
it took approximately 100 days for the clogging mat to form, whereas at 5° C,
the mat developed within 10 to 20 days, but was followed by effluent ponding.
This ponding was attributed to the accumulation of organic compounds that were
not decomposed rapidly enough at the low temperature. For safety, the
investigators recommend depth of greater than 2 feet in sands and an applica-
tion rate of less than 10 cm/day. This is twice the maximum rate allowed by
many state design codes. The separation distance is one-half to two-thirds of
the Region V states' requirements for all soils.
The period before clogging occurs corresponds to the critical phase of
the operation of a new system. During this time, high loading rates may allow
the transport of pathogens deep into soil or groundwater. A newly installed
septic tank system at an Illinois State Park was implicated as the source of
well water contamination that resulted in an outbreak of 60 cases of gastro-
enteritis. The system had been installed in accordance with the local code,
but during installation, groundwater was observed at 10 feet below the soil
surface and the well water was reported to be turbid for a short period after
installation (Center for Disease Control, 1972). It has been noted that tur-
bidity strongly influences pathogen persistence and movement by protecting the
pathogen from inactivating agents (Pipes, 1978).
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Concurrent column studies of silt loam were conducted by Ziebell et al.
(1975b). Silt loam soils, which are characteristic of aggregrated soils, have
a slower permeability than do coarser-textured soils, but are easily
saturated. At a loading rate of one cm/day and with no clogging present,
effluent short-circuited through larger pores. Significant numbers of
bacteria were detected in the column effluent, which presumably was due to the
short retention times that did not permit adequate purification. Brown, et
al. (1978) observed similar bacteria movement down root channels, or cracks in
their 2 year lysimeter test of a sandy clay soil. When Ziebell et al. reduced
the loading rate to 0.3 cm/day, greater bacterial removal was achieved. The
authors indicated that two feet of slowly permeable soils having deep ground-
water tables would provide sufficient protection against microbial contami-
nation of groundwater. In similar soils with shallow groundwater tables,
however, a greater soil depth would provide for a margin of safety.
Other investigators have singled out the importance of soil type and
saturation level as key factors in bacterial removal. In a review of the
literature regarding subsurface pollutant travel (Brown and Caldwell, 1977),
it was concluded that in aerobic, fine-textured, unsaturated soils, most
bacteria will be removed within a distance of two to three feet from the
drainfield trench surface; however, if any one of these three conditions is
not present, then bacteria travel might be much greater. This same review
reports that a few feet of aerobic, unsaturated soil will reduce bacteria
below detectable levels, while the same removal may require over 200 feet in
coarse-textured, saturated soils. Fine soils are effective in removing
bacteria, but they are saturated easily and then may lose some of their
effectiveness. The coarser soils promote aerobic conditions, which are
favorable for bacteria removal, but with the more rapid percolation rate, if
the groundwater table is near, microbial contamination might result. Satu-
rated flow regimes in any soil will force the soil water downward at a faster
than normal rate, thereby reducing retention time and purification (Peavy and
Groves, 1977) and increasing contamination potential.
Several investigators that have evaluated soils' ability to remove bac-
teria from domestic wastewater have specified the minimum soil depth that is
necessary for this removal. Otis (1975) indicates that field monitoring of
operating conventional septic tank systems has shown that two feet of natural
soil is sufficient to reduce bacterial populations in septic tank effluent to
background levels. Brown et al. (1978, 1979) evaluated bacterial removal in
sandy loam, sandy clay, and clay soils. Fecal coliforms rarely were found
below one foot from the bottom of the trenches in all soils and only occa-
sionally were they detected at four feet and then only at low concentrations.
Peavy and Groves (1977) demonstrated in their study that fecal coliforms were
removed within four feet in sandy soils. Tyler et al. (1978) report that at a
distance of one foot into soil surrounding a trench there was a three log
reduction in bacterial numbers and that within the second foot, counts were at
the acceptable range for fully treated wastewater. Finally, from a survey of
conventional on-site systems operating in unsaturated, medium sand soils,
Bouma et al. (1972) found that bacteria were removed rapidly in the soil and
that bacteria beyond one foot below and to the side of the trench were similar
to the natural soil microflora.
From the proceeding discussion, it should be clear that it is not pos-
sible to specify, with any certainty, the separation distance between the
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bottom of septic tank soil absorption systems and water tables. Many site-
specific factors are involved and must be considered in the determination. In
many favorable situations, two to four feet of unsaturated soil may be suf-
ficient for removal of bacteria and protection of groundwater.
c. Bacterial Survival
If pathogenic bacteria are not removed from the septic tank effluent
within a few feet of the drainfield by filtration, adsorption, or die-off,
they may survive temporarily. In general, pathogen survival in soil is
dependent on the microbiological and biochemical properties of the pathogen,
soil properties, and environmental conditions (Miller and Wolf, 1975). More
specifically, some of these factors include soil texture, organic matter
levels, pH, moisture content, temperature, and competition from native soil
microflora.
In a study to determine the survival of bacteria, Rudolfs et al. (1950)
found that colder temperatures and higher moisture levels in soils increased
the survival rates of Salmonella typhi, the causative agent in typhoid fever.
These investigators reported survival times of 2 years in frozen moist soils
as compared to 24 hours in a peat soil, which has a low pH. It has been
suggested that lower temperatures enhance bacterial survival by extending the
lag period before exponential die-off begins (Seidler, 1979).
Zibilske and Weaver (1975) also investigated the effects of temperature
and moisture content on the survival of bacteria. Moist clay and sandy loam
soils were injected with Salmonella typhi and stored at different tempera-
tures. After 12 weeks, 33% of the soil samples that were stored at 5° C and
22° C yielded viable bacteria. Whereas, at 39° C, only 25% of the soil
samples contained S. typhi after 1 week. Bacteria survival rates then were
compared in moist, flooded, and air-dried soil samples. In the moist and
flooded soil samples, S. typhi was recovered from 25% of the samples after 12
weeks. After 1 week, 33% of the air-dried soil samples contained the bac-
teria.
Results of another study indicate that bacteria added to sterile soil
samples will survive longer than in non-sterile soils because of the lack of
antagonism from native soil bacteria. Survival rates also are increased when
high levels of organic matter are added to soil. Because sewage is high in
organic matter content, it would likely enhance survival rates by providing a
source of nutrients (Dazzo et al., 1973).
Wide ranges for bacteria survival times are reported in the literature.
Patterson et al. (1971, as cited by Viraraghavan 1978), compiled data on
survival rates for various types of bacteria in soil. Survival time for
Salmonella ranged from 25 to 41 days and for coliform bacteria, 4 to 90 days.
Miller and Wolf (1975) presented slightly higher ranges of 1 to 85 days and
100 to 150 days for Salmonella and coliform bacteria, respectively. These
ranges apparently reflect differences in soil types and environmental condi-
tions of the experiments.
Bacterial survival in water is affected by many of the same factors that
are important in soil. Generally, low temperatures, high organic matter
levels, and reduced competition increase survival times in water. McFeters et
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al. (1974) compared die-off rates of fecal indicator bacteria and enteric
pathogens in fresh well water. They determined the time that was required for
a 50% reduction in the initial population. The half-time averages for coli-
form bacteria was 17 hours and for fecal streptococci, 22 hours. Die-off
rates for several types of pathogenic bacteria in water ranged from 2.4 hours
to 26.8 hours. With these survival rates, pathogens could move considerable
distances from the source of contamination while remaining infective.
d. Bacteria Migration
As has been shown, fecal bacteria and pathogens may survive relatively
long periods and during this period may be transported deep into the soil or
water table. Microorganisms are not capable of migration per se, but rather
they are carried along by liquid flowing through the soil (Viraraghavan 1978).
Generally, many of the conditions that may prevent the removal of pathogenic
bacteria from septic tank effluent within the first few feet of soil are the
same conditions that are responsible for the increased survival times and
travel distances.
Although there are many other factors involved, subsurface bacterial
movement is affected primarily by soil texture and moisture content (Harkin et
al., 1979). Coarse-textured soils such as sand or loamy sand allow greater
bacterial travel than finer-textured soils like silt loam or clay loam.
Miller and Wolf (1975) indicate that coliform bacteria may move more than 200
feet in a coarse gravel-sand, but that distances are much shorter in finer
textured soils. Brown and Caldwell (1977) reviewed the literature on bac-
terial subsurface travel from septic tank systems and concluded that
essentially all bacteria are removed within two to three feet in unsaturated
soils. However, conditions could be present that could result in much further
transport. They report that microorganisms may travel more than 325 feet
(100m) if water saturates the soils below the drainfield creviced bedrock
exists at shallow depths or coarse-grained soils extend from the ground sur-
face to the water table.
Hagedorn et al. (1978) and Rahe et al. (1978) both found movements of
fecal coliforms over long distances in relatively short times. Travel rates
in the saturated soils were as fast as 50 feet per hour. This rapid movement
was thought to be due in part to flow through the larger pores and root chan-
nels in the soil. Travel rates were greatest during periods of heavy rain-
fall. Other investigators have estimated that bacterial movement may be from
five to ten times greater in saturated soils than in unsaturated soils (Peavy
and Groves, 1978). Movement of bacteria through bedrock was shown by Allen
and Morrison (1973) to be rapid. Liquid in bedrock flows through the fracture
lines or joints, where the seepage velocity can be great, and leads to rapid
and wide dispersal of bacteria in groundwater. In their study, tracer bac-
teria moved 94 feet in 24 to 30 hours. These studies highlight some of the
conditions under which bacteria have been transported far and quickly.
Once pathogenic bacteria are introduced into the aquatic environment,
they may persist for hours to days under the right conditions, and may be
widely dispersed from the source of contamination. Evidence of bacterial
travel also can be found in epidemiological studies. The pathogenic bacteria,
Shigella sonnei, was implicated as the causative agent in an outbreak of 1200
cases of gastrointestinal illness in Richmond Heights, Florida, during 1974.
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A community water supply well was contaminated with insufficiently treated
effluent from an on-site disposal system at a church day care center located
150 feet from the well. A breakdown in the chlorination facility resulted in
the distribution of contaminated water (Craun, 1977). In another disease
outbreak, four members of a household in Washington state contracted typhoid
fever as a result of well contamination from a septic tank system that was
located 200 feet from the well (Center for Disease Control, 1972). Well water
in the area was drawn from a shallow, gravel aquifer. Dye that was injected
into the septic tank system reached the well in 36 hours.
Ground and surface waters in unsewered areas where no overt disease symp-
toms are reported have been found to contain excessive bacterial concentra-
tions. In an area south of Tacoma, Washington, there was a 70% increase per
year in median coliform bacteria concentrations in local streams, with median
concentrations of 64 MPN/100 ml in 1962, 280 MPN/100 ml in 1969 and 1200
MPN/100 ml in 1973 (DeWalle and Schaff, 1980). Lakes in the area, which had
significant lakeshore residential development and septic tank usage, also
experienced bacterial contamination, but the actual concentrations were lower
than in the stream because of dilution effects. The proportion of lakes in
the area that exceeded the 240 MPN/100 ml standard was 19% in 1970, 42% in
1971, and 46% in 1972. The highest bacteria concentrations, averaging 64,000
MPN/100 ml, were found in roadside ditches, which the investigators attributed
to the surfacing and runoff of undiluted septic tank effluent. Microbial
contamination of groundwater also was evident. Although values were very low,
coliform bacteria were present in water supply wells that drew water from 31
feet, 228 feet, and 503 feet.
Seidler (1979) states that runoff across land with malfunctioning
domestic drainfields can have two undesirable impacts on the bacteriological
quality of ground and surface waters. One effect is demonstrated immediately
by the first flush phenomenon of heavy rains. In this case, high numbers of
pathogenic bacteria can be carried to nearby waters. The second effect is
manifested later and is the result of prior bacterial accumulation in sedi-
ments that are later shed into the water and are capable of regrowth during
warm, low flow conditions.
These two effects were demonstrated in a study that was conducted in a
rural watershed near Corvallis, Oregon (Seidler, 1979; Lamka et al., 1980).
Six times during the 15-month project, private well and spring water supplies
in a rural neighborhood of 78 households were sampled for total coliforms,
fecal coliforms, standard plate count bacteria, and Staphylococcus aureus, a
common agent of food poisoning. During the survey, 35% of the households were
found to be using water contaminated with bacteria. Climatological and
seasonal trends were also identified. The highest incidence of coliform
contamination was noted for the sampling days that had been preceded within 24
hours by rainfall. Also, the occurrence of high total plate counts increased
during the warmer spring and summer months compared to the cool months. Nine
different species of enteric bacteria, including opportunistic pathogens, were
identified during the study. The use of septic tank systems in soils
generally unsuitable for use in drainfields was seen as a contributing factor
to the poor water quality in the area (Seidler, 1979). The study area was
characterized as having seasonally high water tables, shallow or slowly per-
meable soils, and steep slopes. This study demonstrated a seasonal effect on
bacterial water quality; maximum coliform bacteria levels were observed
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during the winter months when most of the rainfall and soil leaching occurred.
Generally, the rainy season or even a major storm event preceded by a long dry
spell provides the greatest potential both for surface water contamination by
enteric organisms as a result of surface runoff from septic tank system
failures and for groundwater contamination from subsurface movement under
saturated flow conditions (Seidler, 1979).
Other investigators also have evaluated the bacteriological effects of
septic tank failures on water quality. Reneau et al. (1975) found no effect
in areas without failing systems, but reported total coliform and fecal coli-
form concentrations greater than 2.4 x 10 MPN/100 ml in areas where surface
seepage of septic tank effluent was evident. The authors noted that 83% of
the soil types in the area were marginal or unsuitable for septic tank drain-
fields.
In another study, private water supplies in three rural communities in
South Carolina were tested for total coliforms, E_._ coli, and fecal strep-
tococci; analyses indicated that 85%, 43%, and 75% of the water supplies were
contaminated with the three indicator organisms, respectively (Sandhu et al.,
1979). The presence of E. coli shows recent contamination because the bac-
teria cannot survive long outside its natural habitat. The presence of fecal
streptococci in the water samples was seen as further confirmation of human
sources of fecal pollution, because no farm animals were located near the
water wells. The investigators attributed the bacterial pollution of the
water sources in the study area to the inability of the septic tank leach
fields to operate effectively in removing pollutants. The highest bacterial
counts were found in an area where soils generally were waterlogged, a condi-
tion that is conducive to septic tank failures and which probably enhanced the
bacterial pollution potential of groundwater. Data from the study suggest
that bacterial counts decreased as well depth and it distance from the septic
tank increased.
2. VIRUSES
Viruses differ fundamentally from enteric bacteria. Whereas bacteria
normally are present in the human intestinal tract and in on-site disposal
systems, virus presence is sporadic and only occurs when a household member is
experiencing an enterovirus infection. These infections are most prevalent
during July, August, and September (University of Wisconsin, 1978). Viruses
cannot multiply outside a living cell as bacteria can, nor do viruses require
nutrients for survival. Virus particles are extremely small. They range in
size from 18 NM to 25 NM (less than one millionth of an inch), as compared to
an average size of 750 NM for bacteria (Wellings, 1979). The small size plays
an important role in their survival and migration in the environment. Also
important is that they are electrically charged and, as such, are removed from
percolating septic tank effluent primarily by adsorption rather than by fil-
tration.
There are more than 100 different enteric viruses that can be excreted in
human feces and can cause disease (U.S. EPA, 1978). These viruses include:
the picornavirus group, one of which is poliovirus, the causative agent in
paralytic poliomyelitis; echovirus, which is responsible for meningitis,
respiratory disease, and diarrhea; and coxsackieviruses, which are capable of
causing herpangina, myocarditis, and pleurodynia, as well as the three dis-
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orders noted for echoviruses (Gerba et al., 1975a). Direct evidence for viral
etiology of a waterborne outbreak, however, is limited to hepatitis A,
adenovirus, and the Norwalk agent (Keswick and Gerba, 1980). This is due
largely to limitations of methodologies for the detection of viruses in water
and sensitivity of epidemiologic methods for enterovirus diseases.
Although viral contamination has been demonstrated in groundwater in a
limited number of studies, groundwater often is used without treatment in
rural areas. There is an indication that only one viral plaque-forming unit
(PFU) is capable of producing human infection (Sproul, 1975); therefore, the
presence of even small numbers of virus in groundwater that is used for direct
consumption poses a potential health hazard. Furthermore, a person may con-
tract a viral infection from contaminated water without overt symptoms devel-
oping and, as a carrier, could transmit the virus by person-to-person contact
(Gerba et al., 1975b).
Viruses may enter surface waters by overland runoff containing surface
seepage of septic tank effluent. This comes from individual on-site systems
that are located near lakeshores or stream banks. Densities in bottom sedi-
ments may be many times greater than in overlying waters (van Donsel and
Geldreick, 1971). Viruses initially adsorbed to sediment particulate matter
may be resuspended in response to currents, storms, swimming, or motorboat
activity and may still retain their infectivity.
a. VIRUS SURVIVAL
Enteric viruses are more resistant to environmental factors than are
enteric bacteria and they tend to survive for longer periods (Marzouk et al.,
1979; .Romero, 1970). This is partly because soils generally are less
efficient in removing viruses than they are for bacteria (Pipes, 1978). There
are a number of factors that control virus survival in soil, including soil
texture, presence of organic matter, ionic strength, adsorption, and pH, as
well as microbial antagonism, temperature, and moisture content (Keswick and
Gerba, 1980).
Several investigators have evaluated the effect of some of these factors
on virus survival in soils. Yeager and O'Brien (1979) conducted laboratory
studies using saturated sand and sandy loam soils and storing them at dif-
ferent temperatures. At 37° C, poliovirus was recovered for up to 12 days, at
22° C it was recovered up to 92 days, while at 4° C, polivirus was recovered
from the soils for up to 180 days. The authors concluded that the persistence
of poliovirus in saturated soils was temperature dependent, regardless of soil
type; however, they also noted that adsorption to sandy loam and soil appeared
to protect the viruses, whereas adsorption to sand had little effect on the
rate of poliovirus inactivation. Results of other experiments indicated that
soil dewatering by evaporation destroyed at least poliovirus and cocksackie in
six different soil samples; these results suggest that enterovirus contamina-
tion of soil that is used for wastewater disposal may be reduced or eliminated
by allowing the soil to dry between applications.
As part of the Small Scale Waste Management Program, the role of tempera-
ture on inactivation of sorbed viruses was investigated. Minicolumns filled
with sandy soil were dosed with labeled virus. After 4 weeks at 6° to 8° C,
57% of the virus was still infective, whereas only 2.5% of the infectivity was
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recovered after 4 weeks at room temperature (18° to 24° C). Even after 8
weeks, the sorbed viruses were not inactivated any further in the columns
stored at the colder temperature. Additionally, the cold columns allowed
approximately 10% of the applied virus to pass through with the effluent. The
investigators concluded that sand is less retentive and virus inactivation
occurs more slowly, if at all, at low temperatures (University of Wisconsin,
1978).
The results of these studies generate some concern about the operation of
subsurface disposal systems. There is some indication that virus inactivation
is more rapid near the surface than in subsurface layers because of the
detrimental effects of aerobic soil microorganisms, evaporation, and higher
temperatures (Keswick and Gerba, 1980). Therefore, the viruses that penetrate
the soil more deeply are expected to survive longer than those retained near
the soil surface. This, coupled with the evidence that enteroviruses survive
longest during cool weather and can survive freezing (Hain and O'Brien, 1979),
leads to the concern for potentially prolonged periods of contamination.
Viruses that are deposited during the winter could possibly move to the
surface or deeper into the soil or groundwater during the spring snow melt
when flooding or saturated soil conditions are common in the northern Region V
states. Even heavy rainfall or septic tank usage could permit migration of
infective viruses into groundwater (Yeager and O'Brien, 1979).
Viruses have been shown to exhibit survival time of from weeks to months
in aquatic environments. Water temperature especially influences survival,
with high temperatures promoting inactivation and low temperatures promoting
survival (Hill et al., 1971; Katzenelson, 1978). Essentially all factors that
were noted as affecting virus survival in soil also effect survival in water.
Winneberger (no date) has taken data that were compiled by Prickett and Cooper
(1968) and has presented survival times for nine enteric viruses in different
aqueous environments under various experimental conditions. Poliovirus
organisms have been shown to survive from 17 days to 6 months in surface
waters. It has been demonstrated that infectious hepatitis viruses have
survived 1 month in groundwater and more than 10 weeks in infected spring
water. Hain and O'Brien (1979) also reported that infectious hepatitis virus
was shown to remain infective for 10 weeks in contaminated well water. It is
reasonable to expect longer survival times in groundwater than in surface
waters because the effects of sunlight are eliminated and temperatures are
lower (Keswick and Gerba, 1980).
b. VIRUS REMOVAL
Viruses in septic tank effluent are removed primarily by adsorption onto
soil particles and to lesser extents by bacterial enzymatic attack and natural
die off (Sproul, 1975). Some viruses that are adsorbed to large solids may be
removed by entrapment as well. Adsorption is not irreversible. It is depen-
dent on soil composition; presence of cations, soluble organics, and clay; pH;
and flow rate. Desorption may occur as these variables are altered, thus, the
term "removal" may be inappropriate (Wellings, 1979).
The efficiency of soils for virus adsorption is closely related to soil
composition. Viruses are negatively charged and adsorb readily to clays and
to some silty soils, under appropriate conditions. Sandy loams and soils that
contain organic matter also are favorable for virus removal. In comparison,
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sands or gravel are coarser materials and have relatively smaller surface
areas per unit volume or weight and are not as efficient in removing viruses
(World Health Organization 1979). Good virus removal has been shown in
sands, but other factors such as loading rate (University of Wisconsin, 1978),
temperature, or soil conditioning (Green and Cliver, 1974) become more
critical than soil texture.
Yeager and O'Brien (1979) compared the virus adsorption capacity of sand
and sandy loam. The sandy loam soils, which had significantly higher clay
content, cation exchange capacity, and organic matter and a lower pH, adsorbed
more viruses than did the sand. These results and the importance of these
soil characteristics are in agreement with other published reports (Bitton
1975; Gerba et al., 1975b).
Soil pH and cation concentration both have been shown to affect virus
removal in other laboratory studies. Drewry and Eliassen (1968) conducted
batch studies on five soils and found that virus adsorption increased with
decreasing pH, in the range of 6.8 to 8.8, and increased with increasing
cation concentrations. They indicated that decreasing the pH of the soil
reduces the negative charge and thus decreases repulsion between the viruses
and the soil. It also has been noted that while low pH favors adsorption,
high pH can result in elution of adsorped viruses (World Health Organization,
1970).
Carleson et al. (1968) found that high concentrations of cations usually
enhanced virus adsorption. Cations present in soil solution do have a pro-
found effect on reducing the repulsive potential of soil and virus particles.
This leads to a formation of a soil-cation-virus bridge and the virus is
immobilized. Aluminum ions are more effective in the removal of viruses from
percolating wastewater than calcium ions, which in turn are more effective
than sodium ions.
Lance et al. (1976) conducted column studies using attenuated polio-
viruses. Most viruses were adsorbed in the top two inches (five cm) of the
soil in the columns. Flooding the column surface for 27 days with virus-laden
wastewater did not exhaust the capacity of this top layer to immobilize
viruses. The effects of rainfall were simulated by flooding the columns with
distilled water within 24 hours after virus loading had ceased. This caused
the viruses to desorb and to move through the eight-foot columns. If the
distilled water was applied more than 24 hours after infiltration of the
effluent, viruses were not desorbed. Apparently, both the time factor and the
low ionic strength of the distilled water affected desorption. The authors
concluded that viruses would not penetrate to groundwater unless rains were
heavy, the water table was near the surface, or the soil was very coarse or
shallow.
Investigators on the Small Scale Waste Management Project at the
University of Wisconsin (1978) concluded from their own laboratory studies and
from a review of the literature that the most important factor in virus reten-
tion by soil is flow rate. They found that in systems operated under satu-
rated or rapid flow conditions, a smaller percentage of the applied viruses
was removed when compared to columns that received moderate loading rates,
which reduced virus levels by several orders of magnitude. The more saturated
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the soils, the less opportunity there is for virus contact with surfaces to
which it can adsorb. Their summary of findings also includes:
• sandy soils without structure and loaded at less than or equal to five
cm/day should remove viruses adequately within two feet;
• structured soils with no clogging mat present would require lower
loading rates to achieve purification within two feet;
• loading rates are less important in clogged soils where the infil-
tration rate is limited by the clogging mat, unless surfacing of
effluent occurs saving to excessive application.
It is extremely difficult to specify the minimum depth of soil necessary
for virus removal. Researchers at the University of Wisconsin recommend at
least two feet of sand and low application rates. Another source generalized
that soil with reasonable amounts of silt and clay are effective in removing
virus in less than two feet of soil (State of California, 1978). But as has
been indicated, a number of variables can influence the removal efficiency of
soils. The problem becomes more complex when one considers that viruses
retained near the surface may be eluted and may migrate as a result of heavy
rainfall or septic tank usage (Lance et al., 1976). It also has been reported
that viruses can be desorbed in a low ionic environment and in the presence of
organic matter without loss of infectivity (Gerba and Schaiberger, 1975).
c. VIRUS MIGRATION
Many of the specific factors that affect virus movement in groundwater
have not been studied directly. These hydrogeological, biological, and
meteorological factors (Keswick and Gebra, 1980) have been identified in pre-
vious sections. Although some indication of the factors that promote or are
detrimental to viral persistence and movement can be determined in controlled
laboratory studies, it often is not possible to generalize to field conditions
where numerous site-specific variables may intervene. Most of the evidence
for migration of viruses has been obtained from field investigations in which
viruses have been isolated from drinking water wells in the vicinity of septic
tank systems or from monitoring wells that intercept groundwater beneath
wastewater land application sites. Review of these studies provides some
information about the conditions under which viruses have been known to enter
groundwater systems. At present, this knowledge of viral movement is incom-
plete and sometimes contradictory.
Mack et al. (1972) reported isolation of poliovirus from a 100-foot
drinking water well that was responsible for a gastrointestinal outbreak at a
restaurant in Michigan. It was postulated that some other, unidentified virus
was probably the causative agent in the outbreak. The source of enteroviruses
was a septic tank drainfield that was located 300 feet from the well. The
viruses had to penetrate 18 feet of clay, 8 feet of shale, and 74 feet of
limestone to reach the well. Very low levels of coliform bacteria were
detected, however, no pathogenic bacteria were isolated in water samples.
An outbreak of infectious hepatitis at Posen, Michigan, was attributed to
septic tank effluent. Only a few feet of soil separated the bottom of the
drainfield and the highly permeable limestone aquifer, which was the source of
drinking water for the area. Percolating water from melting snow and spring
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rains carried the virus-laden effluent into groundwater, which was withdrawn
by nearby drinking water wells. Other areas in the Great Lakes Region have
experienced similar groundwater contamination as a result of malfunctioning
septic tanks or from systems located in unsuitable soils (Weist, 1978).
An outbreak of 51 cases of gastrointestinal illness and 15 cases of
hepatitis A at a migrant labor camp in Florida was reported by Wellings et
al., (1975a). Echovirus was detected in 35 to 40-foot drinking water wells.
One well was located 100 feet from a solid waste disposal area and five others
were located in an area bordered by septic tank systems. The outbreak
occurred during a dry spell and the investigators reasoned that the heavy
pumping had increased the groundwater gradient and flow rate down from the
septic tanks toward the wells. Viruses survived in chlorinated water and
existed in the absence of bacterial indicator organisms.
Baer et al. (1977) reported an outbreak of 50 cases of hepatitis A, 26
with jaundice, that occurred in a rural Alabama school. The school obtained
its drinking water from two small springs that received seepage from septic
tanks. The investigators noted that periods of heavy rainfall, which probably
aided in the transport of the virus, had preceded the onset of the outbreak.
These studies demonstrate that soil type and structure, proximity of well
to source of sewage, rainfall, and other factors can affect viral movement
from septic tank systems into groundwater and that viruses can persist in
chlorinated water and in the absence of indicator organisms. These investi-
gations, however, were prompted by disease outbreaks; reports of negative
results of tests for viruses in groundwater near septic tanks are not as
likely to be published. Also, private water supplies located near on-site
disposal systems normally are not monitored routinely and viruses could only
be detected present in domestic wastewater if someone is infected. It is
likely that most operating soil absorption systems effectively remove
enteroviruses from septic tank effluent.
Additional evidence for migration of enteroviruses can be obtained from
reports of land application and groundwater recharge projects. It should be
noted, however, that sites are generally selected with sandy soils that permit
rapid percolation but may also have the least capacity for virus removal.
This is especially true for recharge programs. Wellings et al. (1974) re-
covered virus from groundwater beneath a wastewater irrigation site. Viruses
survived secondary treatment, including chlorination, and exposure to sunlight
and still penetrated through 10 to 20 feet of sandy soil. Detection of virus
in groundwater occurred after heavy rains.
Wellings et al. (1975b) later demonstrated lateral movement of entero-
viruses in groundwater after discharge of secondary sewage effluent into
cypress domes, which are ponded continuously. Viruses were shown to move from
the application point through alternating sand and clay layers to a depth of
at least 20 feet and over a horizontal distance of at least 125 feet to where
the monitoring wells were located. Viruses survived up to 28 days in this
study. Again, isolations generally followed heavy rains.
Other investigators have demonstrated even greater virus travel distances
in groundwater. Vaughn et al. (1978) detected viruses in groundwater 35 feet
beneath wastewater recharge basins at installations located on Long Island,
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New York. They also showed horizontal transfer of up to 150 feet. Viral
concentrations in observation wells at the groundwater recharge sites ranged
up to 10.6 PFU/gallon. Schaub and Sorber (1977) reported viral migration
distances at a rapid infiltration site in Massachusetts. The soil at the site
consisted of unconsolidated silty sand and gravel of glacial origin over
bedrock. Groundwater contained viruses at depths of 95 feet and at lateral
distances of 600 feet from the point of application. These studies indicate
that entrainment in aquifers can result in significant lateral movement of
viruses.
Other rapid infiltration projects, however, have produced renovated
wastewater free of viruses. For example, throughout the 10 years of operation
of the rapid infiltration project at the Flushing Meadows site in Arizona,
viruses were never detected in the renovated wastewater wells. The average
virus concentration of the applied secondary effluent was 2,118 PFU/100 ml
(Bouwer et al., 1980). At this site, renovated wastewater has completely
replaced native groundwater. Viruses also were not detected in the renovated
water sampled below the Whittier Narrows and the Santee, California, sites nor
the San Angelo, Texas, installation. These success stories tend to indicate
that, under certain conditions, the soil can be an effective medium in re-
moving viruses from wastewater and in limiting the potential impact on ground-
water quality.
3. FATE OF NUTRIENTS DISCHARGED FROM ON-SITE SYSTEMS
The nutrients that have the greatest potential for creating environmental
or human health problems are phosphorus (P) and combined forms of nitrogen
(N). Adverse effects may arise if excessive amounts of either of these
nutrients enter nearby lakes or streams or if nitrogen reaches an aquifer that
is used as a source of drinking water. High levels of nutrients, especially
phosphorus, may accelerate eutrophication of surface waters because they are
essential nutrients for algae and aquatic weeds. Algae growth and oxygen
depletion may result, which in turn may create conditions that are aestheti-
cally unpleasing or that are detrimental to aquatic fauna and flora.
Some forms of nitrogen present in drinking water pose potential health
hazards. Nitrate (NO ), the end product of nitrification, and nitrite (N0_),
the intermediate form, can be toxic to humans if ingested in large amounts
(University of Wisconsin, 1978). Infant methemoglobinemia has been linked to
these nitrogen forms. Also, there is evidence that nitrosamines, which are
formed from the reaction of NO with secondary amines, are carcinogenic to
laboratory animals. A limit for nitrate of 10 mg/1 as nitrogen in drinking
water has been recommended.
Phosphorus and nitrogen normally are present in household wastes and thus
are present in septic tank effluent. In most properly functioning septic tank
soil absorption systems, phosphorus, will be immobilized readily in the soil;
thus, phosphorus enrichment of groundwater seldom occurs beneath these sys-
tems. The same system, however, is not as effective in nitrogen removal.
Most, if not all, of the nitrogen that leaves the house will eventually be
converted to nitrate. Nitrate is not retained by soils, and it will be
carried with the effluent into the groundwater. Dilution by uncontaminated
groundwater is then the only significant mechanism of reducing NO- concen-
trations to safe levels (University of Wisconsin, 1978).
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Many field and laboratory studies have been conducted to investigate
under what conditions phosphorus and nitrogen from conventional on-site sys-
tems may enter ground and surface waters and degrade water quality. These
investigations are reviewed in this section.
a. Phosphorus in Household Wastewater
Most of the phosphorus that is present in domestic wastewater originates
from washing activities that use phosphorus-based cleaning agents. The rela-
tive amount from this source has decreased since limits on phosphorus deter-
gents have been imposed. Phosphorus also is contributed by toilet usage.
Phosphorus is present in organic and polyphosphate forms, which are converted
to soluble orthophosphate.
Several investigators have conducted chemical analyses of septic tank
effluents to determine the phosphorus concentrations that reach soil absorp-
tion systems and to compare these levels with the concentrations found in
groundwaters adjacent to the systems. Values that are reported show a good
deal of variability, which probably results from differences in the type and
amount of waste products present and the wastewater flow, age of the system,
and sampling and analytical procedures (Dudley and Stephenson, 1973). Otis et
al. (1975) monitored effluent concentrations from six septic tank systems over
a 2-year period and found average effluent concentrations of total phosphorus
to range from 11.0 to 31.4 mg/1 with a median value of 12 mg/1. Dudley and
Stephenson (1973) have compiled literature values and report a wider range of
average total phosphorus concentrations from 5.4 to 70 mg/1 with a higher mean
of 25 mg/1.
b. Phosphorus Removal
Phosphorus is removed from septic tank effluent and retained in the soil
by adsorption and precipitation reactions. Adsorption is controlled primarily
by the mineralogy of the soil and to a lesser extent by soil particle size
(Jones and Lee, 1979). Clay minerals have relatively higher capacities for
phosphate adsorption than do coarse sand or gravel (Hook et al., 1978). Iron,
aluminum, and calcium cations are involved in phosphorus reactions. In
neutral to acid (non-calcareous) soils, the phosphate ion becomes adsorbed
onto surfaces of iron and aluminum compounds, while in neutral to alkaline
(calcareous or limestone) soils, calcium minerals predominate in adsorption
(University of Wisconsin, 1978).
As the concentration of phosphorus increases, precipitation reactions may
occur if the soil contains sufficient quantities of a cation that would form
an insoluble compound with the phosphate anion. At normal septic tank
effluent pH levels, phosphate precipitates of calcium, in the form of
hydroxyapatite, usually result (Hook et al., 1978). In hardwater areas, phos-
phorus is precipitated readily because of the calcium carbonate that is pre-
sent in the soil and groundwater (Jones and Lee, 1977). Aluminum or iron
phosphate also may occur but the pH of the effluent is not as likely to favor
these reactions except during the first few months of system operation (Hook
et al., 1978) or if the system is located in non-calcareous soils (University
of Wisconsin, 1978).
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Many field studies have demonstrated that most soils, even some sandy
soils, are very efficient in reducing phosphorus concentrations before
effluents reach groundwaters. Reductions of 80% to 90% of the applied phos-
phorus loading within a period from two to five days have been reported by
Tofflemire et al. (1973 as cited in Jones and Lee, 1977). Distances required
for comparable reductions range from a few inches (Miller and Wolf, 1975) to
about 15 feet in sandy soils with some silt or clay (Dudley and Stephenson,
1973). Generally, phosphorus moves very slowly through the soil. If the
phosphorus is not removed immediately below the soil absorption field, there
is evidence that it can be removed by soil and sediment within the groundwater
(Childs, 1974). Phosphorus is normally present in very low concentrations in
naturally occurring groundwaters with a typical range of from 0.01 to 0.06
mg/1 P (Jones and Lee, 1977).
In some cases, however, the system may not be able to immobilize per-
manently all the phosphorus to which it is exposed. System overloading may
result from applying too much phosphorus or by applying it too rapidly. Even
under normal operation, the absorptive capacity of a soil decreases with the
age of the system as exchange sites for phosphorus become saturated (Dudley
and Stephenson, 1973). There is also the possibility of leaching. Phosphorus
retained by soils can be redissolved and transported by fluctuating water
tables or by exposure to waters of low phosphorus concentrations. In these
situations, the movement of phosphorus in subsurface soil layers is likely,
depending on the application rate, percolation rate, and soil pH (Sawhney and
Starr, 1977). Temperature and other chemical and biological variables are
involved also (Hall, 1975). This potential for movement is of particular
concern at lakes where distances between septic tank systems and lakeshores
may be limited and phosphorus movement into the lake may be rapid.
Although there is a finite capacity for soils to absorb phosphorus, it
has been demonstrated that resting the system regenerates absorption sites and
that the soil is capable of removing additional phosphorus from wastewater
over longer periods. In a field study by Sawhney and Starr (1977), a six-
month rest period was sufficient to regenerate the absorption capacity. The
septic tank system that was used in the study had two parallel absorption
trenches that could accept the effluent; most conventional septic tank
systems, however, do not have this unique feature.
When subsurface disposal systems are installed with proper attention
given to soil characteristics and local hydrogeological factors and when they
are located at adequate distances from receiving water bodies, the complete
removal of phosphorus from septic tank effluent by soil generally is possible.
Because many systems currently are operating without satisfactory removal
efficiencies, they represent good candidates for evaluation. The results of
these studies aid in the understanding of which factors adversely affect
removal efficiences and allow the movement of phosphorus into groundwaters or
nearby lakes and streams.
c. Phosphorus in Waters Near On-Site Systems
Because of the potential for adverse effects on surface water quality
resulting from groundwater transport of phosphorus from septic tanks, a number
of field investigations have been undertaken to determine the factors that
affect phosphorus movement. Many of these studies have been conducted in the
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Region V states where a large number of rural lakes are located and where
accelerated eutrophication of these lakes is a potential problem. Phosphorus
contamination is evidenced by elevated concentrations in groundwaters below
septic tank systems or in nearby surface waters; it is inferred by shoreline
algal growth on lakes with rural residential development. Lawn or garden
fertilization on lakeshore home sites, however, is a confounding variable.
Bouma et al. (1972) measured orthophosphate (PO,) concentrations in
groundwaters below five conventional septic tank systems located in sands in
central Wisconsin. Groundwater adjacent to two of the five sites had rela-
tively high phosphorus concentrations. One system was 12 years old and was
located in loamy sand soil. The other system was 8 years old, was located in
medium to fine sand and peat, and occasionally was flooded by a fluctuating
water table. At this site, phosphorus was transported by groundwater into a
lake 90 feet away. Phosphorus concentrations equal to background levels (0.02
to 0.03 mg/1 PO, P) were found beneath a system that was less than one year
old and another one that had an intervening clay layer between the system and
the water table, which was about 20 feet below. These results indicate that
system age, soil type, and location of water table can affect phosphorus
transport.
Eleven more existing on-site disposal systems in Wisconsin were evaluated
for phosphorus removal efficiency by Dudley and Stephenson (1973). Phosphorus
removal was most effective at sites that were underlain by medium to fine
grained sands or in sands with some silt or clay. The authors concluded that
at sites with these characteristics, total phosphorus levels should be at
background concentrations within 10 to 20 feet of travel from the point of
release. Low phosphorus concentrations also were found at sites with rela-
tively new systems. Significant levels (> 1.00 mg/1 total phosphorus) were
found at four sites. Three of these systems were underlain by medium to
coarse grained outwash sands and gravel with high permeabilities. The other
site was situated in very impermeable soils derived from glacial till. The
unsaturated zone beneath these systems ranged from 7 to 56 feet. Based on
their study results as well as on a review of the literature, Dudley and
Stephenson (1973) concluded that phosphorus enrichment of groundwaters could
occur where septic tank soil absorption systems are located above high water
tables or in coarse sandy subsoil, receive heavy loadings, and are relatively
old. Although elevated phosphorus concentrations were found beneath some
absorption fields, in at least one of these sites the groundwater flow was not
toward the lake, so it is unlikely that the added phosphorus load from this
system would directly degrade the lake water quality. The investigators
suggested that the greatest potential for phosphorus reaching lakes from
lakeshore on-site systems would occur in poorly drained soils with high water
tables or in coarse sands with naturally low absorptive capacities for phos-
phorus .
Childs (1974) conducted a three-year waste migration study of septic tank
effluents around Houghton Lake, Michigan. Results from three of the study
sites indicate the importance of the chemical composition of the soil in
phosphorus removal and document vertical and horizontal travel distances. One
septic tank system (site 1) was located in medium to coarse soil (Rubicon
sand). The water table was five to six feet below the ground surface and
sloped toward a canal that eventually fed into the lake. The system had been
used heavily by a family of six for 15 years. Background phosphorus concen-
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trations averaged 0.02 mg/1 PO, - P. Although present in fairly low levels
(0.1 to 0.3 mg/1), orthophosphate still was detected at distances of 100 feet
laterally and 4 feet vertically from the system. Groundwaters below two other
systems (sites 4 and 7) showed higher phosphorus concentrations and further
travel distances. These systems were situated in fine-grained soils (Newton
loamy sand) and just two feet above the water table. Both systems had been in
use by families of six for about 10 years. High phosphorus levels extended 6
feet into the groundwater and values as high as 8 to 14 mg/1 were measured at
the lake's edge 120 to 150 feet away. Directly offshore from one of these
sites, aquatic plants were observed; groundwater flow direction at the site
was toward the lake. A water sample from the anomalous weed bed had a
concentration of 1.09 mg/1; mean lake values ranged from 0.03 to 0.08 mg/1.
These study results are in contrast with other studies that have indi-
cated that fine-sized soils are more efficient for phosphorus removal than are
coarser soils because of the greater surface areas and retention times.
Childs (1972) suggests that the chemical makeup of the soil and sediment is
more important than particle size alone in phosphorus retention. Soils at
site 1 were rich in calcium, aluminum, and iron cations, which formed
insoluble compounds with phosphorus and thus were more favorable for
adsorption. There also was a greater depth of soil between the system and the
water table at this site than at the others.
Childs (1974) also estimated the quantity of phosphorus from on-site
systems that was transported annually to Houghton Lake by groundwater. It was
estimated that residents discharge 40,000 pounds of phosphorus per year
through septic tank systems but that only 1000 pounds reach the lake; this
represents a removal of 98%. He also determined that the phosphorus adsorp-
tion capacities of soils above the water table in the area ranged from six
months to six years. Because the phosphorus was not present in the local
groundwaters and only limited amounts could be absorbed above the groundwater,
Childs concluded that phosphorus must be retained by soils and sediments in
the groundwater. He further concluded that the adsorptive capacity of soil
may be as great under saturated as under unsaturated conditions and that
phosphorus is not available for groundwater transport until after the soil and
sediment filter is saturated with phosphorus.
Sawhney and Starr (1977) also investigated vertical and lateral movement
of phosphorus from a septic tank drainfield. They found that movement
occurred in both downward and horizontal directions and that phosphorus con-
centrations were similar at equal distances below and beside the trench.
Background phosphorus concentrations were evident at a depth of two feet. The
researchers concluded that in a soil with a deep water table, a distance of
two feet should effectively remove phosphorus, but that more distance would be
required for removal in shallow soils with high or perched water tables. No
description of the soil texture was given.
Other investigators have not found favorable phosphorus removal
efficiencies under saturated flow conditions or in the saturated zone. Peavy
and Jones (1977), in their evaluation of a septic tank drainfield in a clay
loam and silty clay loam soil, noted that although very little phosphate
reached the groundwater, once the effluent reached the aquifer, apparently no
substantial removal occurred. Reneau (1979) observed greater phosphorus
movement in both fine and coarse loamy soils under saturated flow conditions
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because of the lower effective soil volume that was available for phosphorus
removal. In unsaturated flow conditions during low water table levels, he
found that phosphorus adsorption was enhanced as a result of the increased
contact and the availability of larger surface areas.
Gibbs (1977) also evaluated the effect of a fluctuating water table on
phosphorus removal efficiency of lakeshore soils. The investigation was
conducted at Lake Taupo, New Zealand, where increased draw-off of lake water
for electricity generation simulated a fluctuating water table. During the
summer high lake levels, the pumice soils removed only 24% of the effluent
phosphorus, whereas at the lower lake levels, during the autumn and winter,
the removal efficiency was 74%. At the lower groundwater and lake levels,
more soil is exposed for purification. When this soil becomes submerged in
water of low phosphorus concentration as the water table rises, the nutrients
could be flushed out, leaving the soils with a higher removal efficiency for
the next exposure. The cyclic flushing, however, provided a mechanism by
which an estimated 80% of the discharged effluent reached the lake. High
phosphorus levels were found in the lake bottom bed and decreased with
distance from the shore. Macrophyte weeds were observed on the banks of some
bays off the lake.
In summary, inefficient removal of phosphorus in a system generally
implies the inability of the immediate soil area to reduce the concentrations
to background levels or to prevent the movement of phosphorus into surface
waters. Generally, finer-textured soils are better for removal than coarser
soils because of increased particle surface area and contact time under
unsaturated flow conditions. Good removal, however, has been obtained with
sandy soils, particularly if there is some silt or clay. The chemical pro-
perties, of the soil may be as significant, or more so, as particle size alone.
Soils rich in aluminum, calcium, or iron oxides enhance phosphorus adsorption
and precipitation reactions.
The literature is not definitive on the depth of soil that is necessary
for reduction of phosphorus concentrations in septic tank effluent to back-
ground levels. Generally, the greater depth available between the bottom of
the drainfield and the water table or bedrock, the greater protection against
phosphorus contamination of underlying groundwaters. This is especially
important in poorly drained soils or in soils with naturally low adsorptive
capacities for phosphorus. In many situations, a separation distance of two
to four feet of soil will be adequate.
In general, phosphorus removal from percolating wastewater is enhanced
under unsaturated flow conditions more than in saturated regimes. This is
evidenced by removal efficiencies in soils with fluctuating water tables, with
greater efficiencies occurring when the water table is low. There is the
indication that although a rising water table can regenerate absorption sites
by redissolving the absorbed phosphorus, this flushing action also results in
the movement of phosphorus. Depending on the nature of the soil and ground-
water, additional removal may occur in the water table.
Removal efficiency is decreased while the potential for migration is
increased as the phosphorus absorption sites become saturated. This can occur
from sustained heavy loading or with system age. Although a soil has a finite
capacity for the adsorption of phosphorus, through regeneration mechanisms
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induced by wetting and drying cycles or by alternating absorption beds, the
capacity of a soil can be prolonged.
Most of the studies involve individual systems that are isolated from
other sources of contamination in order to describe the behavior of phosphorus
from septic tank systems. Lawn fertilizers are a source of phosphorus too.
Thus, any algae growth on the immediate shoreline from a household with a
septic tank may be a result of the fertilizers or effluent, or both. In rural
lakeshore communities, along with the hydrogeologic factors, septic tank
densities, proximity of units to the lake, and groundwater flow patterns all
become involved in whether the lake will be adversely affected.
d. Nitrogen in Domestic Wastewater
The major sources of nitrogen in domestic wastewaters are feces and
urine, which contain urea, uric acid, ammonia, undigested foodstuffs, and
bacterial cells (Sikora and Corey, 1976). In the anaerobic environment of the
septic tank, nitrogen is mineralized rapidly to ammonia by microbial enzymes.
The nitrogen in septic tank effluent is about 75% ammonia (NH.) and 25%
organic nitrogen (Otis et al., 1975). Average effluent concentrations from
six septic tank systems had ranges of 32 to 76 mg/1 for total nitrogen and
from 20 to 46 mg/1 for ammonia. Combined nitrate and nitrite concentrations
in the analyzed effluent samples were less than 1 mg/1.
e. Nitrogen Transformations and Removal Mechanisms
The organic nitrogen in septic tank effluent is dissolved or suspended.
Some is removed from solution by biological decomposition into simple forms
and then adsorbed by soil particles and clays (Dudley and Stephenson, 1973).
The rest of the organic nitrogen is mineralized to ammonia and these undergo
the same reactions discussed below.
In a properly functioning system, aerobic conditions normally will pre-
vail in the soil underlying the absorption field, but if the soil is submerged
or oxygen is depleted, anaerobic conditions are favored. In such cases,
ammonia could be leached to the groundwater before nitrification could take
place. The amount that would reach the water table would depend on the number
of cation exchange sites exposed to the effluent, the affinity of these sites
for ammonia, the composition of the effluent, and the degree of cation ex-
change saturation with ammonia (Sikora and Corey, 1976). A more detailed
description of the conditions that interfere with the formation of nitrates is
provided in the next subsection.
The primary transformations of nitrogen that occur in the soil are
nitrification and denitrification. Nitrification, or the process by which
ammonia is oxidized first to nitrite and then to nitrate, is accomplished by
bacteria that require aerobic conditions. As previously noted, aerobic
conditions normally exist in the unsaturated zone below a drainfield and thus
the formation of nitrates is very likely. This is of concern because of the
public health and pollution hazards that are posed by excessive concentrations
of nitrates in groundwater. Nitrification generally occurs rapidly and within
a short distance of the drainfield. The point at which nitrification of the
ammonia is complete will depend on the contact time and the rate of nitrifi-
cation, which in turn is affected by pH, aeration and moisture conditions,
number of nitrifiers, and temperature (University of Wisconsin, 1978).
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The amount of nitrate that is removed by plant uptake is minimal. This
mechanism is evidenced by the characteristic lush growth often present near
septic tank systems. The quantity of nitrogen that is discharged from a
septic tank far exceeds what can be used by plants (Sikora and Corey, 1976).
Some removal of nitrate is feasible through denitrification, the
microbiological process in which nitrate and residual nitrite can be reduced
to nitrous oxide (N_0) or free nitrogen (N ). For NO and NO to be present,
nitrification must occur first. DenitriTication of oxidized nitrogen is
desirable but it can occur only in an oxygen deficient environment and in the
presence of a carbon energy source (Miller and Wolf, 1975). Anaerobic condi-
tions can exist beneath an aerobic zone if prolonged periods of saturation
have occurred. For poorly drained soils or slowly permeable soils, which may
enhance saturated flow and hence anaerobic conditions at depths in the soil
profile, the loss of nitrates through the denitrification process may be
significant. However, in most cases it is unlikely that both of these
reactions will occur at a site because of the opposite aeration requirements
of each (Sikora and Corey, 1976).
If nitrates are not removed either by plant uptake or through denitri-
fication, they likely will reach groundwaters and possibly surface waters.
This is because nitrate is a soluble anion and the cation exchange capacity of
soil is ineffectual in the adsorption of nitrate as it moves with the per-
colating effluent (Miller and Wolf, 1975). Once the nitrate has reached the
water table, the only mechanism by which nitrate concentrations are reduced is
through dilution.
Nitrogen can be introduced into the environment by sources other than
septic tanks. This further increases the potential for nitrate contamination
of ground and surface waters. Lawn and garden fertilizers, animal feedlots,
and barnyards are all sources of nitrogen. Decomposing vegetation, accom-
panied by climatic and land use patterns, can supply nitrates and can lead to
their subsequent migration into groundwaters as well (McNabb et al., 1977).
f. Factors That Affect Nitrogen Transformation and Movement
Although nitrates normally are found in excessive amounts a short dis-
tance below absorption fields, conditions may be present initially that would
prevent nitrification from even occurring. This would result in high ammonia
concentrations in groundwaters downgradient from septic tank systems. Dudley
and Stephenson (1973) found ammonia concentrations of more than 10 mg/1 at two
of their eleven study sites in Wisconsin that were both situated in imper-
meable glacial till soil, which apparently did not allow the proper aeration
for nitrification to occur. Elevated concentrations also were found
occasionally at other sites in sandy soils with water tables less than five
feet below the absorption fields. In all their study sites, ammonia concen-
trations averaged 15 mg/1 below the drainfields and never exceeded 1 mg/1 at
horizontal distances greater than 50 feet, thus, the ammonia is apparently
attenuated fairly quickly by soil adsorption.
Evaluation of existing septic tank systems by researchers at the
University of Wisconsin identified other conditions that may lead to high
ammonia levels. In one system that was used intermittently, the effluent
percolated rapidly, so nitrification did not always occur. Other findings
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from these studies indicate that high ammonia concentrations will be present
beneath sites where the depth of the aerobic zone between the drainfield and
groundwater is less than two feet. Seasonal differences also have been noted.
During the winter ammonia levels were observed to increase because the lower
temperatures slow the rate of nitrification and thereby increase the distances
needed for complete nitrification. Under conditions of saturated flow, very
little nitrification takes place and ammonia concentrations are high.
Viraraghavan and Warnock (1975) found higher ammonia values in the winter when
low temperatures and high water tables existed concurrently.
Although it may appear to be desirable to prevent the conversion of
ammonia to nitrate by installing septic tank drainfields in line with the
previously identified factors, many of those same factors may have other
equally bad or worse side effects. For example, an absorption field that is
located a few inches above a water table may not provide sufficient soil
volume for nitrification, but at the same time neither would it provide for
pathogen removal. Also, the addition of ammonia to surface waters may exert
considerable demands for oxygen. Thus, there are obviously many trade-offs
involved in the renovation of septic tank effluents.
Several investigators have reported that when conditions for nitrifica-
tion are present, the oxidation of ammonia to nitrate is rapid and complete.
Walker et al. (1973a, 1973b) concluded that nitrification will occur readily
if three to six feet of unsaturated soil separate the drainfield from the
water table. In an investigation of five study sites in permeable sandy soils
in central Wisconsin as part of the Small Scale Waste Management Project,
nitrification was generally found to be complete within two to six inches
below the clogging mat. Two other studies, which are referenced in a litera-
ture review by the University of Wisconsin (1978), indicate that nitrification
is complete within one to two feet (Preul and Schroepfer, 1968; de Vries,
1972). This finding also was supported by Dudley and Stephenson (1973).
As noted previously, nitrate may move extended distances, with dilution
being the primary mechanism involved in decreasing its concentration. Studies
that are cited in the University of Wisconsin report (1978) have demonstrated
that from 50 to 100 feet of travel in groundwater may be required to lower
nitrate concentrations in septic tank effluent to below 10 mg/1 (Preul, 1966;
Dudley and Stephenson, 1973). Concentrations above background levels have
been observed 330 feet downgradient from septic tank systems, with the highest
concentrations several feet below the water table level rather than at the
surface (Ellis and Childs, 1973).
Other investigators, as a result of their case studies of nitrate con-
tamination, have attempted to specify septic tank or population densities that
are necessary to accomplish acceptable dilution in an unsewered community.
Walker et al. (1973) indicated that septic tank systems would not contribute
significant amounts of nitrates to groundwaters in rural watersheds when the
density of residences is less than one per 0.5 acre. Lower densities in other
areas, however, have been associated with nitrate contamination. For example,
Woodward et al. (1961), in their survey of 39 communities in Minnesota, found
that when population densities were 2.7 persons per acre, 29% of the wells
experienced nitrate contamination, but when densities were 0.5 person per
acre, only 2% of the wells were contaminated. Insufficient dilution of
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nitrates from septic tank systems were found in Nassau County, Long Island,
where population densities exceeded three persons per acre (Smith and Myott,
1975, as cited in Hook et al., 1977).
These investigations have significant implications for rural lake com-
munities where higher population or septic tank densities are common and
distances to water supply wells and lakeshores are often short. Although
septic tank density is one of the major factors affecting nitrate contamina-
tion of a local area, there are many other site limitations and hydrogeo-
logical conditions that also influence nitrate pollution in groundwater (Scalf
et al., 1977; Schmidt, 1977). Several of these other factors have been
identified in case studies of regional or areal nitrate contamination of
groundwaters.
g. Cases of Nitrate Contamination
One early demonstration of widespread groundwater contamination in un-
sewered areas in Minnesota was given by Woodward et al. (1961, as cited in
Dudley and Stephenson, 1973). They sampled 63,000 private wells in 39 com-
munities; 48% of the wells sampled had significant nitrate concentrations and
about 11% of the 48% (5.3% of the total) values greater than 10 mg/1. Several
factors were identified to explain the variability among communities and the
elevated concentrations. Soil type was considered important; no contamination
was apparent in areas where a continuous clay horizon was present. Increases
in well depth led to improvement in measured water quality. Of the older
systems that were installed prior to World War II, 50% of the wells were
contaminated with nutrients and coliform bacteria. Only 10 to 20% of the
newer systems were contaminated. As already indicated, population density
also correlated with nitrate contamination.
Delfino (1977) referred to a statewide survey of approximately 6000 pri-
vate wells in rural areas throughout Wisconsin that was conducted from 1968 to
1972 by Schukrecht et al. (1972, 1975). Of those wells sampled, about 550, or
9.2%, had nitrate concentrations greater than 10 mg/1. An intensive survey
also was conducted in Columbia County in south-central Wisconsin. Shallower
wells tended to have higher nitrate concentrations, as did wells located close
to known pollution sources. Of 33 wells tested that were located within 50
feet of sewage seepage areas, 27% had concentrations greater than 10 mg/1.
Proximity to barnyards, feedlots, and manure storage piles, however, resulted
in many more contaminated wells than did locations near septic tanks.
Brooks and Cech (1979) conducted a nitrate and bacteria survey of
domestic water supplies in a rural east Texas community. Sands are the pre-
dominant soil type in the area. Fifty-three privately owned wells that were
less than 350 feet deep were sampled. The wells with the highest observed
concentration of nitrates were those located close to septic tanks. When set
back distances were less than 15 feet, concentration of nitrates exceeded 10
mg/1; and when wells were located within 50 feet of the septic tank systems,
nearly 50% of them had concentrations greater than background (0.9 mg/1).
Elevated nitrates were found in more dug wells, rather than drilled, or in
wells that were less than 50 feet deep. The authors concluded that the major
cause of high nitrate levels was the improper location of septic tanks and
wells with respect to each other, which apparently created a direct recycling
of drained fluid from septic tanks to wells.
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Two unsewered communities in the coastal plain of Delaware were investi-
gated for the causes of nitrate contamination in private water supplies
(Miller, 1975). One of these areas was characterized as having an extremely
high water table, poorly drained and periodically waterlogged soils, and
occurrences of overflowing septic tank systems during rainy months. Low
nitrate levels were found in private water wells, and concentrations decreased
with rising water tables. It was hypothesized that nitrogen compounds were
never oxidized to nitrates but remained as ammonia or organic nitrogen in the
groundwater. The same hydrogeologic factors, however, contributed to the high
coliform bacteria levels that were measured in the wells.
In the other area, soils were deep and well-drained. More than half the
samples collected from shallow wells had concentrations greater than 10 mg/1.
Nitrate concentrations ranged from 5 to 30 mg/1, thus indicating that the
permeable soils and low water table favored the oxidation of nitrogen com-
pounds to nitrates and their movement into the water table. Pathogenic
organisms were removed successfully by the soils. Miller (1975) concluded
that when the water table is generally less than five feet, bacterial contami-
nation from overflowing absorption fields and septic tanks is likely. When it
is greater than five feet, nitrate contamination is possible.
More recently, Robertson (1979) analyzed 800 groundwater samples from
wells in Sussex County, Delaware, and found that more than 20% of the wells
had nitrate concentrations greater than 10 mg/1. The greatest incidence,
however, was associated with animal feed lots. Septic tank effluent also was
considered a significant source of nitrates, as were fertilizers, forest
foliage, and precipitation.
Because of the public health concern regarding the consumption of exces-
sive amounts of nitrates, relatively more attention has been devoted to docu-
menting its presence in drinking water wells than in surface waters. One
study, however, noted a gradual increase in nitrate concentrations in both
ground and surface waters over a 30-year period that was attributed to the
presence of sewage effluents from septic tank drainfields (DeWalle and Schaff,
1980). River water samples in the 104-square-mile study area, which was south
of Tacoma, Washington, had a mean nitrate value of 1.3 mg/1 and a maximum
value of 8.6 mg/1. Mean nitrate concentrations of lakes in the area were 0.36
mg/1 with maximum winter values of 2.4 mg/1. Phosphorus concentrations during
the winter similarly were elevated and the investigators noted that sub-
stantial algae blooms resulted every summer. Although nitrate concentrations
in excess of 10 mg/1 may have a health significance, much lower concentrations
may contribute to eutrophication of surface waters (Peavy and Groves, 1978).
4. OTHER CHEMICAL CONTAMINANTS
There are other chemical contaminants that occasionally could be present
in domestic wastewaters. Because of the eutrophication effects of phosphorus
and nitrogen and the toxic nature of nitrogenous compounds in drinking water,
these contaminants were discussed separately. The intent of this section is
to address briefly the type and extent of water quality impacts that could
result from the inadvertent or intentional discharge of toxic or other chemi-
cal pollutants into septic tank systems.
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a. Toxic Chemicals
Many synthetic organic chemicals commonly are used in household products,
such as Pharmaceuticals, disinfectants, deodorants, polishing agents, deter-
gents, cosmetics, paints, and pesticides (Scalf et al., 1977). If the use of
these products is not consumptive, then liquid wastes containing potentially
harmful chemicals may enter the septic tank drainfield. Under some condi-
tions, these chemicals might reach nearby surface or groundwaters.
Many of the organic substances are physically trapped, chemically
changed, or biologically degraded in the aerobic soil layers below properly
functioning septic tank soil absorption systems (Brown and Caldwell, 1977).
In addition to the properties of the chemical itself, there are other factors
that affect removal, particularly the type, structure, and chemical composi-
tion of the soil (State of California, 1978). The soil bacteria population
also is a factor because these microorganisms are important in the decomposi-
tion of organic compounds (Miller and Wolf, 1977).
Although many chemicals are removed successfully, the soil is not an
effective medium for removing the more stable soluble chemicals. A review of
past studies (Brown and Caldwell, 1977) indicates that stable chemical com-
pounds such as gasoline, phenols, and herbicides have been shown to travel
distances from less than 1 mile to more than 20 miles from their disposal or
application site. Furthermore, there is some indication that those organic
substances that are removed initially may be desorbed later and may not be
degraded before they enter ground or surface waters. Thus, exposure to chemi-
cal pollutants far from their source of application is possible. Mobility of
chemical constituents in septic tank effluent appears to be dependent on
properties of the soil, oxygen status of the soil, pH, and characteristics of
the contaminant (Brown et al., 1978).
Pesticides often are singled out as especially dangerous pollutants
because many of the chemicals that are used in the formulations generally are
toxic to many nontarget species, including humans. Their presence in domestic
wastewaters would not be expected normally and, if present, their concentra-
tions probably would be very low. Once in the soil, pesticide residues move
very slowly downward (Miller and Wolf, 1977). Pesticides are absorbed by clay
particles, iron and aluminum oxides, and organic colloids and they are subject
to microbial degradation (State of California, 1978). Soil studies that have
been conducted under laboratory and field conditions indicate that most pesti-
cides remain in surface soils, while a few with time may penetrate to depths
of one to two feet. Even the more mobile pesticides usually are broken down
rapidly by soil microorganisms. The ones that pose the greatest potential
threat are the mobile pesticides that also are somewhat resistant to decom-
position.
The extent to which pesticides will remain in soils after their applica-
tion depends on several factors, including soil type, moisture, temperature,
pH, and microorganism content. It is assumed that these same factors would
exert similar influences if the pesticides were discharged to a septic tank
drainfield. One of the most important factors is the degree of, and the time
required for, the degradation of the pesticide itself into simpler, nontoxic
forms (Murphy, 1975), which in turn is partly dependent on the water solubili-
ty, molecular, ionic, and volatile character of the pesticide (Miller and
Wolf, 1977).
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The biggest concern regarding the toxic chemical compounds that are
persistent in the environment is their potential hazard to human health if
ingested with untreated drinking water from rural water supplies either in
large doses over a short time or in small doses over a long time. Incidents
of acute chemical contamination generally are easy to detect. Well water may
look, taste, or smell unusual and clinical symptoms of an affected individual
may appear rapidly. The effects of chronic, low-level doses, however, are
harder to predict, or to detect, and the victim's sub-clinical symptoms
generally are difficult to diagnose and to attribute to a causative agent
(U.S. EPA, 1980). No report of chemical poisoning of drinking water from
on-site disposal systems was encountered in the literature that was reviewed.
Likewise, no documented case of an individual septic tank causing chemi-
cal contamination of ground or surface waters was reported in the literature
reviewed. Although the possibility is remote, environmental hazards could
result if groundwater carrying toxic chemicals from rural domestic sources
discharge into nearby lakes or streams. The risk of water quality degradation
due to toxic materials from rural on-site disposal systems seems minimal for
several reasons. First, as noted previously, the presence of harmful chemi-
cals in domestic wastewater is sporadic. Second, if the chemical is subject
to degradation, setback distances from receiving waters generally provide
adequate time for this removal. Finally, when the groundwater mixes with
surface water, dilution reduces the concentration even further. The primary
environmental hazard that could result if toxic concentrations of wastes exist
for prolonged periods in nearby surface waters would be the adverse impact on
the aquatic organisms. A severely toxic substance will eliminate aquatic
biota until dilution, dissipation, or volatilization reduces the concentration
below the toxic threshold (Mackenthum, 1969). Less toxic materials also might
reduce populations of those fish and lower aquatic organisms that are unable
to tolerate the concentration of the toxicant. There is no evidence that
indicates that septic tank systems have caused these effects.
b. Other Septic Tank Effluent Constituents
The predominant emphasis in the literature on water quality impacts from
on-site wastewater disposal systems is on the addition of pathogens and
nutrients to ground and surface waters and their associated effects. This is
because these constituents are the ones most likely to be present in septic
tank effluent and likely to pose human health or environmental hazards. A few
researchers, however, also have included other parameters in their investi-
gations of septic tank system performance.
Brown et al. (1978) conducted a relatively comprehensive assessment of an
existing system. As part of their study, they measured the concentration of
selected metals in lysimeters that were located in sandy, sandy clay, and clay
soils that received septic tank effluent. Concentrations were recorded for
copper, zinc, nickel, lead, and cadmium. Mean soil concentrations for these
metals were highest in the clay soil and were lowest in the sandy soil. In
some cases, the concentrations in the soil adjacent to the septic fields
increased to about two times above the background levels, but these concentra-
tions were still much lower than what would be required to reduce plant
growth. Periodic groundwater samples did not indicate the presence of these
metals above the background. The investigators concluded that because the
concentrations of heavy metals in septic tank effluent are low and because
II-A-28
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they accumulate only immediately adjacent to the drainfield, even prolonged
applications should not cause excessive accumulation in the soil or degrada-
tion of the receiving water.
DeWalle and Schaff (1980), rather than investigating the efficiency of
one system, looked at regional groundwater quality in an area near Tacoma,
Washington, that was dependent on septic tank systems. Using historical data
and statistical techniques, they noted gradual increases throughout a 30-year
period in the groundwater concentrations of several parameters that were
associated with domestic waste from septic tanks. In addition to the
increases observed for bacteria, nitrate, and orthophosphate, noticeable
increases in the groundwater below the unsewered area were observed for
calcium and chloride. Sodium, a major cation in sewage, showed a rather
constant concentration during the period, however. The authors postulated
that this was due to an ion exchange mechanism in which the sodium replaced
the calcium in the cation exchange complex of the clay. Chloride concentra-
tions tended to be higher during the summer months when maximum evaporation
increased the salt content of the leachate.
Other investigators have noted high chloride concentrations in ground-
waters near on-site disposal systems. Chloride is a mobile anion, much like
nitrate, that is typically present in domestic wastewaters in concentrations
much greater than background levels but it has more significance as a tracer
of septic tank effluent than as a pollutant itself (Brown and Caldwell, 1977).
At excessive concentrations in the range of 250 to 500 mg/1, chlorides at the
worst may impart a salty taste to drinking water, interfere with agricultural
processes (Metcalf & Eddy, Inc., 1979), or accelerate corrosion (Gehm and
Bregman, 1976). Generally, levels much lower than these values are observed
near septic tank systems.
Some investigators have used the presence of chlorides in groundwaters to
indicate the rate and direction of effluent movement in general and nitrate
movement, specifically. Chlorides, like nitrates, are not removed readily by
the soil and concentrations for both are reduced primarily by dilution.
Dudley and Stephenson (1973) noted consistently high correlations between
chlorides and nitrates in groundwater below 11 on-site wastewater disposal
systems in Wisconsin and found significant chloride contamination at all
sites. Similar relationships between the two anions also have been observed
by Schmidt (1977) and DeWalle and Schaff (1980).
Although nitrates and chlorides commonly are found in groundwater near
septic tank systems, there are other sources that can contribute chlorides to
groundwater. Thus, in a monitoring program, these sources need to be identi-
fied before septic tanks alone are wrongly accused of causing the contamina-
tion. For instance, in hard water areas, water softeners may add even higher
chloride concentrations to the wastewater. Also, winter road salting or
leachate and runoff from salt piles may increase the chloride content of
groundwater.
II-A-29
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tile system. In: Proceedings of the National Home Sewage Disposal Sym-
posium, Chicago IL, 12-13 December 1974. ASAE Pub. Proc. 175, St. Joseph
MI, pp48-57.
Walker, W. G. , J. Bouma, D. R. Keeney, and F. R. Magdoff. 1973a. Nitrogen
transformation during subsurface disposal of septic tank effluent in
sands: I. Soils transformations. Journal of Environmental Quality
2:475-480.
Walker, W. G. , J. Bouma, D. R. Kenney, and P. G. Olcott. 1973b. Nitrogen
transformations during subsurface disposal of septic tank effluent in
sands: II. Groundwater quality. Journal of Environmental Quality
2:521-525.
Weist, William G. Jr. 1978. Summary appraisals of the nation's ground-water
resources: Great Lakes Region. Geological Survey Professional Paper
813-J.
Wellings, F. M. , A. L. Lewis, and C. W. Mountain. 1974. Virus survival
following wastewater spray irrigation of sandy soils. In: Virus
survival in water and wastewater systems (J. F. Malina, Jr., and B. P.
Sagik, eds.). Water Resources Symposium No. 7, University of Texas,
Austin TX, pp253-260.
Wellings, F. M. , A. L. Lewis, C. W. Mountain, and L. V. Pierce. 1975.
Demonstration of virus in groundwater after effluent discharge onto soil.
Applied and Environmental Microbiology 29:751-757.
Wellings, F. M., C. W. Mountain and A. L. Lewis. 1977. Virus in groundwater.
In: Individual on-site wastewater systems: Proceedings of the Second
National Conference, 1975 (N. McClelland, ed.). Ann Arbor Science
Publishers, Ann Arbor MI, pp6l-66.
II-A-36
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Wellings, F. M. 1980. Virus movement in groundwater. In: Individual on-
site wastewater systems: Proceedings of the Fifth National Conference,
1979 (N. McClelland, ed.). Ann Arbor Science Publishers, Ann Arbor MI,
pp427-434.
Winneberger, J. T. Undated. Setback needed to protect water supplies from
viruses. In: On-site waste management, Series I, Volume II (Hancor,
Inc.), Findley OH, ppl!8-133.
Woodward, F. L. , F. J. Kilpatrick, and P. B. Johnson. 1961. Experience with
groundwater contamination in unsewered area in Minnesota. American
Journal of Public Health 51(8):1130-1136.
World Health Organization. 1979. Human viruses in water, wastewater, and
soil. WHO Technical Report Series 639. Geneva, Switzerland.
Yeager, J. G., and R. T. O'Brien. 1979. Enterovirus inactivation in soil.
Applied & Environmental Microbiology 38(4):694-701.
Zibelske, L. M., and R. W. Weaver. 1975. Survival of salmonella typhimurium
in soil as influenced by varied mositure content and incubation tempera-
ture. Agronomy Abstracts 133.
Ziebell, W. A., D. H. Nero, J. F. Deininger, and E. McCoy. 1975a. Use of
bacteria in assessing waste treatment and soil disposal systems. In:
Proceedings of the National Home Sewage Disposal Symposium. ASAE Publi-
cation Proceedings 175, St. Joseph MI, pp58-63.
Ziebell, W. A., J. L. Anderson, J. Bouma, and E. McCoy. 1975b. Fecal bac-
teria: Removal from sewage by soils. American Society of Agricultural
Engineers Paper No. 75-2579. St. Joseph MI.
II-A-37
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B. THE ROLE OF NEEDS DOCUMENTATION IN ALTERNATIVES DEVELOPMENT
A nearly universal obstacle to sound decisions for wastewater management
in unsewered areas is lack of adequate local data on the design, use, and
water quality impacts of existing conventional on-site systems. The situation
is, of course, even worse for innovative systems.
Collection of performance data is necessary to support Construction Grant
applications for any unsewered areas. The utility of performance data is
obvious if continued use of on-site systems is proposed. If sewers are pro-
posed, the need for them must be documented. This requirement is stated in
Program Requirements Memorandum 78-9:
New collector sewers should be funded only when the systems in use
(e.g., septic tanks or raw discharges from homes) for disposal of
wastes from the existing population are creating a public health
problem, contaminating groundwater, or violating the point source
discharge requirements of the Act. Specific documentation of the
nature and extent of health, groundwater and discharge problems must
be provided in the facility plan.... A community survey of indi-
vidual disposal system is recommended for this purpose.
Other eligibility criteria for collector sewers are included in PRM 78-9.
These criteria and their sequence of application in eligibility decisions are
presented in Figure II-B-1 as interpreted from PRM 78-9. The crux of this
decision flow diagram is that a need must be documented for a gravity collec-
tor sewer to be eligible. Then, if the need is demonstrated, it must be shown
that the sewer is the cost-effective means to satisfy the need.
Additional guidance on documentation of need is provided by Program
Requirements Memorandum 79-8:
Facility planning in some small communities with unusual or incon-
sistent geologic features or other unusual conditions may require
house-to-house investigations to provide basic information vital to
an accurate cost-effectiveness analysis for each particular problem
area. One uniform solution to all the water pollution problems in a
planning area is not likely and may not be desirable. This exten-
sive and time-consuming engineering work will normally result in
higher planning costs, which are expected to be justified by the
considerable construction and operation and maintenance cost savings
of small systems over conventional collection and treatment works.
Though house-to-house visits are necessary in some areas, sufficient
augmenting information may be available from the local sanitarian,
geologist, Soil Conservation Service representative or other source
to permit preparation of the cost-effective analysis. Other sources
include aerial photography and boat-carried leachate-sensing equip-
ment which can be helpful in locating failing systems. Detailed
engineering investigation, including soil profile examination,
percolation tests, etc., on each and every occupied lot should
rarely be necessary during facility planning.
II-B-1
-------
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Based on application of these policies during preparation of the Seven
Rural Lake EIS's, Region V in cooperation with states in the Region, developed
additional guidance on the collection and use of performance data titled
"Region V Guidance--Site-Specific Needs Determination and Alternative Planning
for Unsewered Areas." It is attached to Technical Reference Report XVI-D as
Appendix A. A key feature of this guidance is the recommended sequencing of
data collection with decisions on development and selection of alternatives so
that all necessary data are collected in a timely manner and unnecessary data
collection is avoided.
The Region V Guidance also emphasizes performance as the relevant
criterion for need. Though this seems obvious, facilities plans and state
policies often rely on nonconformance with current design codes as the
criterion for need. Use of nonconformance alone as a criterion would result
in the abandonment of many older systems, even though they may have many more
years of use remaining.
The Region V Guidance was prepared so as to apply to almost any com-
munity. It is, therefore, more complex than would be necessary in many cases.
Conditions under which the recommended needs documentation/alternatives devel-
opment process might be simplified are discussed in Technical Reference Report
XVI-D.
II-B-3
-------
C. REVIEW OF DIRECT AND REMOTE SENSING TECHNIQUES
1. INTRODUCTION
This section outlines groundwater and earth sensing techniques that can
provide important data for the planning, design, and monitoring of on-site and
small-scale wastewater treatment facilities.
Sensing methods can be categorized as either direct or remote. Direct
sensing refers to on-site observations, well-drilling operations, and the
measurement of physical and chemical parameters within water, soil, and rock
samples. Remote sensing methods are indirect, non-destructive means of data
collection that take advantage of the physical and chemical properties of
matter.
Electromagnetic waves are constantly emitted from or reflected by water,
animals, plants, and earth materials and can be detected from aircraft and
satellites. When provided with sufficient ground truth reference data, an
investigator can evaluate land use, plant growth trends, temperature condi-
tions, and geological structures by the use of aerial photography and imagery.
Seismic techniques are based on the sound propagation characteristics of
earth materials.
Electrical methods study the ways in which rocks and soils conduct in-
duced or naturally occurring electrical currents.
Thermisters can be used to evaluate temperature variations in soil
columns.
a. Direct Sensing
Human beings gather more information through vision than through all
other senses combined. On-site inspection of proposed wastewater treatment
sites is absolutely essential to obtain first-order approximations of topo-
graphic restraints, soil textures and wetness, man-made structures and excava-
tions, and the variety and condition of vegetation. Soil erosion problems can
be identified, and the apparent operating conditions of nearly all treatment
systems evaluated. Visual inspection is the only way to accurately note and
record the locations of data collection points such as wells, springs, lakes,
and rock outcrops.
Soil parameters are of greatest priority in evaluating the potential
surface or subsurface land treatment of wastewater. "Grab" samples can be
obtained directly from the surface, but this is not representative of the
entire soil vertical column. The use of a hand auger, mechanical auger, or a
soil core tube sampler enables the investigator to document soil horizonation
and classification, and to identify shallow groundwater levels. Relatively
undisturbed samples of the entire soil column can be obtained after digging a
trench that penetrates to the regolith. Soil samples of this type can sub-
sequently be chemically and physically analyzed and subjected to permeability
testing.
II-C-1
-------
Rock samples can be collected from in situ outcroppings in and near the
proposed site, then compared with published geological data for the region. It
is important to identify any underlying aquifer systems that would potentially
be degraded by surface or subsurface land treatment systems, especially in
proximity to recharge zones.
The measurement of surface water and groundwater parameters may be neces-
sary to establish baseline conditions and to monitor future trends resulting
from wastewater system discharges. Nearby streams, rivers, and lakes should be
studied"" as appropriate to obtain relevant information such as:
• Temperature variations,
• Stage levels and flow velocities for streams and rivers, especially
low flow conditions (measured with flow meters and weirs),
• Secchi disk turbidity measurements, and
• Chemical analyses of water samples, including
- pH
- Conductivity
- Nitrates
- Bacteria
- Viruses
- Phosphorus
- Sulfates
- Iron
- Aluminum
- Manganese
- Hardness (calcium, magnesium, carbonate)
Groundwater samples should be collected from springs and existing
(strategically chosen) wells in or near the proposed site and analyzed for the
temperature and relevant chemical parameters such as those listed above. Data
collection of surface parameters should ideally coincide with remote sensing
by aerial photography or imaging in the event that the latter methods are also
used.
Borehole drilling data are appropriately collected when moderate to
large-scale (more than 5000 gallons per day) land application systems are pro-
posed, when groundwater resources are particularly sensitive, or when the area
being evaluated will contain numerous treatment systems or is near an eco-
system sensitive to nutrient inputs (for example, a lake or bog). Drilling
enables the direct sampling of geological formations in the form of core
sections, drill cuttings, or sidewall samples. Such boreholes can be outfitted
with screens and surface casings to function as trend-monitoring wells. Such
wells provide immediate access to groundwater for the purposes of measuring
water temperatures and elevation, pH, conductivity, and chemical composition.
Suction pumps cannot be used to sample water columns in wells more than 30
feet deep. Reactive gases released from well waters can be trapped by keeping
wells capped, periodically sampled, and analyzed with a gas partitioner or gas
chromatograph. Given access to wells, old or new, the investigator can perform
Samples should be collected during low-flow and storm conditions to establish
variations.
II-C-2
-------
aquifer pump testing (Walton, 1970; Davis and DeWiest, 1966) to ascertain the
transmissivity and storativity values for the penetrated formations. Knowledge
of these formation "constants" enables the prediction of future groundwater
movements within a local or regional flow system.
b. Indirect Sensing
Indirect sensing techniques are used to monitor the physical phenomena
associated with matter and energy, which include:
• potential fields (gravity and magnetics),
• electrical characteristics, and
• energy emittance and reflectivity.
Of the above, electrical and energy characteristics can be used in the
remote sensing of environmental problems.
Indirect sensing data have significance only when they can be contrasted
with parameters measured directly in the medium under investigation. In geo-
physics, for example, seismic and resistivity surveys can accurately determine
the depths to zones of earth materials having contrasting physical properties.
But without direct samplings of the strata, it will not be known what pro-
perties are being contrasted. Ideally, both ends of geophysical transects
should be correlated with locations of boreholes or other sources of subsur-
face information like rock outcroppings and deep excavations. In this way the
parameters of lithology, structure, and water table levels are established at
two points and the geophysical profiles allow reliable extrapolations between
these known points. Similarly, periodic remote sensing by aerial photography
can show subtle changes in surface reflectivity, but environmental interpre-
tations are useless in the absence of a well-documented ground truth data
base.
2. GEOPHYSICAL METHODS
a. Seismic Techniques
Seismic refraction can be very useful in extrapolating the subsurface
geological and hydrological conditions between known data locations like
drillholes. Sonic impulses are generated by a variety of destructive or non-
destructive means in the earth and detected at specified distances by geo-
phones. The first signal to reach a geophone located close to the energy
source will be the wave that travels directly through the soil along the
surface of the earth (surface wave). At greater geophone distances, the first
arrival signals will be those refracted from higher velocity subsurface
layers, such as consolidated rock or water tables. Depths to these interfaces
can be calculated from the distance and travel times from the energy source to
a geophone, but parameters such as lithology and zones of saturation cannot be
determined unless the seismic profile is tied to locations of known subsurface
data .
II-C-3
-------
Relatively simple, single-channel seismic refraction instruments are
commercially available. A single geophone is used at varying distances to
record signals generated by striking a metal plate with a hammer. A single-
integrating memory recorder is a highly desirable feature which, when used,
enables the detection of weaker refracted signals.
Refraction methods are very useful tools in the reconnaissance of water
tables in areas for which there are only a few data locations. Refraction
works best in geological columns with thick sections of unconsolidated
material. This is a common characteristic of glaciated terrains in the north-
central and northeastern United States.
Reflection techniques differ from refraction in that the desired data are
arrival times of seismic waves reflected from successively deeper interfaces
of contrasting acoustic transmission. These interfaces are caused by lateral
or vertical changes in subsurface lithology. Conventional seismic reflection
methods are much more costly than refraction techniques. Multi-channel re-
corders are used to increase the efficiency of reflection surveys, utilizing
groups of geophones arranged in complex arrays over the area under investiga-
tion. Shot points are placed at intervals within the phone arrays and the
results recorded. Since some geophones are located near the shot points, first
arrivals of reflected waves often occur during or shortly after the passing of
the surface wave ("noise"), necessitating costly digital filtering and proces-
sing of the data. An advantage of the reflection method is the ability to
penetrate high-velocity zones that overlie low-velocity layers. Refraction
methods cannot correctly interpret these conditions and can only provide
misleading data about them. In general, reflection methods will be overly
sophisticated for application to water resource studies in small waste flows
management.
Microwave reflection is a relatively new technique that is a topic of
ongoing research and development. Theoretically, the method is similar to
conventional seismic reflection, but the acoustic source operates at a much
higher frequency and the depth of penetration into the earth is reduced.
Microwaves can readily penetrate dry materials, but they are greatly attenu-
ated when passing through saturated substances. Thus, microwave reflection is
useful in detecting shallow, water-saturated zones beneath the surface. Con-
ventional seismic reflection gear is generally used to detect fairly deep
targets since it is difficult to differentiate wave arrivals from shallow
reflections and seismic energy sources.
Commercially available microwave systems operate in either pulsed or
continuous wave modes and have been used to detect geological structures such
as faults and caverns at depths greater than 200m. Although water tables can
be identified in this way, resolution can be improved by contrasting simul-
taneously collected pulsed and continuous wave data. Depths to reflective
layers are interpreted from the analysis of electromagnetic interference
patterns generated by this bi-modal technique (Koerner, 1978).
b. Electrical Resistivity
Resistivity techniques can readily be used to detect water table depths.
The flow of direct current is generated in the ground by two electrodes and
the drop in potential between them is measured by another pair of electrodes.
II-C-4
-------
Vertical resistivity profiling would be the appropriate way to detect the
water table on a specific site, utilizing the Wenner electrode arrangement
(Dobrin, 1976). Initially, a small electrode spacing is used. It is sub-
sequently increased until a significant drop in apparent resistivity occurs.
The resulting data are more difficult to interpret than seismic data. The
method relies on matching field data curves to theoretical layer-case curves
in a manner somewhat analogous to that used in evaluating aquifer test data.
Although resistivity data are somewhat difficult to interpret, the equipment
used is generally not as expensive as seismic equipment.
Prior to collecting resistivity data, a prospective site must be in-
spected for the distribution of surface and buried metallic objects like pipes
and fences, which can seriously distort the data. Strong electromagnetic
fields produced by low angle radar and aircraft instrument landing systems
also present limitations for electrical resistivity surveys. The successful
interpretation of geophysical data requires the services of personnel with a
high level of theoretical expertise and field experience.
c. Geothermal Gradient
The relative proximity of groundwater to the land surface can sometimes
be determined by simply measuring soil temperatures. It has been shown that a
thermister in combination with a probe inserted in the soil column can be used
to detect zones of groundwater discharge by means of measured temperature
variations. During winter months, soils in discharge zones are generally
warmer than surrounding soils, which have temperatures close to the ambient
air temperature. Conversely, in summer, soils are often cooler in discharge
zones. Recharge zones are not readily detected in this manner. Data obtained
in this way should not be confused with the geothermal gradients measured in
boreholes to determine the relative values of heat conductivity within the
earth's crust.
3. REMOTE SENSING
In theory, there is no limit to the possible applications of analyzing
the electromagnetic "signatures" of different kinds of matter. At present,
however, the practical uses of remote sensing are limited in their application
to environmental problems because of the complexity of the earth's surface.
Monitoring of this surface is influenced by the many variables that regulate
the emission and reflection of electromagnetic radiation. The following is a
partial list of these variables:
soil variations (specific heat, moisture, and organic content),
rock lithology,
ambient temperature,
sun angle,
barometric pressure,
wind velocity,
humidity,
II-C-5
-------
precipitation,
snow and ice accumulations,
water bodies (oceans, lakes and rivers),
particulates suspended in air and water,
cloud cover,
water chemistry,
effects of man (agriculture, structural engineering, and strip
mining), and
• natural catastrophes (floods, volcanic eruptions, and meteorite
impacts).
Rock lithology is a variable only in an areal sense, unless it is altered
by strip mining or catastrophism. Vegetation undergoes slow seasonal change,
as well as more rapid changes induced by water availability, parasitism, and
disease. Snow accumulations can alter the electromagnetic characteristics of a
surface within a fraction of an hour. Although most surface variations on the
earth are seasonal or diurnal in nature, catastrophic events like volcanic
eruptions can produce radical changes which endure for hundreds or thousands
of years. Man's efforts in agriculture and engineering have completely altered
many natural landscapes.
Because of the extreme variability of the earth's surface, it is apparent
that aerial sensing data have little value unless the information can be
contrasted with data collected simultaneously on the ground. In this way, a
time-correlated data base is accumulated with which to compare future varia-
tions detected by remote methods. Apparent associations between remote sensing
information and ground truth data can be tested with regression analyses.
From the standpoint of earth monitoring, the most useful portions of the
electromagnetic spectrum are the infrared and visible light regions. The
intensity of most of the ultraviolet band is strongly scattered and attenuated
by dust particles in the atmosphere. Two-thirds of the solar energy inter-
cepted by this planet reaches the surface, and can be subdivided as follows:
• 10% Ultraviolet (UV),
• 50% Visible Light, and
• 40% Infrared (IR).
a. Aerial Photography
The first serious use of aerial photography as a sensing technique
occurred during World War I, in which it was used militarily to monitor troop
and equipment concentrations in France. The current state-of-the-art in this
branch of remote sensing owes much of its progress to government financing for
the research of military applications.
Remote sensing via aerial photography can be of practical value in the
trend monitoring of on-site wastewater treatment facilities. Color and
infrared photography can be used in combination to study changes in the types
and concentrations of foliage that occur in response to the availability of
water and nutrients. Remote black and white photography is not of practical
value in the study of foliage differences. Vegetation is in general highly
II-C-6
-------
reflective in the infrared region, and different kinds of foliage reflect
varying amounts of IR. For example, grasses generally reflect more than 70% of
intercepted IR, while fir trees reflect less than 20% (Fritz 1967).
In the event of the failure of a treatment system, a high nutrient load
would be released in the subsurface. During the growing season, such an
occurrence would promote an increased vigor in plant growth, resulting in
greater total IR reflectivity. Surface outbreaks of effluent are even more
apparent, since water is a strong absorber of IR. Such areas generally appear
black on color infrared film.
A serious obstacle to the photographic monitoring of septic systems is
the density of trees and bushes in an area. These plants can sometimes effec-
tively shield a drainage system from remote observation. This obstacle can be
partially overcome by obtaining substantial overlap between photographic
frames. Stereo observation can sometimes reveal malfunction "signatures" that
would otherwise be obscured.
Comparative true color and infrared aerial photography was acquired,
interpreted for surface malfunctions, and field-verified for each of the Seven
Rural Lake EIS's. This effort, made by U.S. EPA's Environmental Photographic
Interpretation Center for Region V, was the first full-scale use of the tech-
nique as a community-wide survey of surface malfunctions from septic tank
systems. Materials and techniques used were published in the appendices to the
Draft EIS's. Another example of the use of comparative color and infrared
aerial photography in the evaluation of septic system performance is reported
by Slonecker (1980).
There is a common misconception that IR photography can be used to detect
subtle temperature differences within an environment. That kind of sensitivity
can only be achieved using an infrared imaging scanner.
b. Optical Scanning Systems
Unlike conventional photography, optical scanning systems are able to
detect very subtle variations in the electromagnetic radiations of matter.
Systems have been developed and used for sensing in the infrared, visible
light, and ultraviolet regions. Infrared scanners have the greatest potential
for applicability to the sensing of environmental phenomena. Although the IR
spectrum lies between the wavelengths of 0.76u and 1000 u, most imagery is
obtained in either the 3 to 5u or 8 to I4u atmospheric "windows."
The basic elements of a scanner are optical mirrors, a signal amplifier,
and an IR detector. In order to increase its sensitivity, the detector is
housed in an insulated jacket filled with liquid nitrogen. An image beam is
focused on the detector by a rotating mirror, generating a signal that is
amplified and modulated for strip-wise projection onto photographic film
(Taylor and Stingelin, 1969). It has been discovered that the greatest equip-
ment sensitivity is achieved by scanning during the early evening hours, thus
avoiding the recording of reflected solar IR energy. Temperature variations of
less than 1°C can be detected in aerial imagery, but only at altitudes of 5000
feet or less.
II-C-7
-------
IR scanning can be directly applied to the planning and monitoring of
on-site waste treatment facilities. The presence of surface or groundwater is
usually associated with a significant thermal gradient in the environment.
Thus, groundwater discharge zones can be readily detected, and surface drain-
age patterns within an area can be much more reliably distinguished than with
conventional photographic interpretations. Structural zones with high trans-
missivities, such as faults and fractures, can often be identified even when
they do not appear in aerial photography. Also, seepage patterns along lakes,
rivers, and canals often produce detectable temperature gradients where the
groundwater first encounters surface waters. Periodic monitoring of soils can
potentially show changes in water saturation due to seepage and precipitation.
Although IR imaging is obviously a useful technique in monitoring ground-
water and surface water movements, it has the disadvantage of being very
costly and requiring special expertise for the proper operation of the complex
equipment. On a regional basis, the technique might best be used to periodi-
cally monitor the apparent performance levels of septic systems, thus identi-
fying areas, localities, and individual systems that may be in need of on-site
inspections. At the same time, patterns of groundwater influx to delicate
ecosystems like lakes, bogs, and marshes can be monitored. Used in this way,
aerial IR imaging may prove to be a cost-effective technique for reducing the
frequency and extent of required on-site inspections, but only in the event
that adequate ground-truth data have been historically collected.
4. SATELLITE IMAGERY (LANDSAT)
In relation to the scope of this paper, the most important contribution
of LANDSAT imagery is its use in the regional classification and monitoring of
trophic conditions in lakes. A classic study of this type was done in
Wisconsin (Holmquist and Scarpace, 1977) making use of LANDSAT multispectral
scanner data.
The objective of the study was to ultimately establish a broad ground-
truth data base to enable the future independent monitoring of lake trophic
conditions via satellite imagery. Four wavelength bands were used, including
portions of the visual and infrared regions. The study involved a statistical
comparison of spectral reflectivity with ground-truth investigations. Surface
data were collected in conjunction with satellite imaging passes. Measurements
included the gathering of Secchi disk data and the collection of water samples
for laboratory analyses of transmittance and reflectance based on suspended
solids. Although rather complex data processing methods were required, a high
percent reliability was achieved in the prediction of trophic levels.
5. CONCLUSIONS
The results of this section are listed in Table II-C-1. The sensing
techniques described are summarized in terms of relative cost, parameters
measured, and types of technical expertise required under ideal staffing
conditions. It is especially important to compare the relative cost of a
technique with its reliability and level of managerial applicability.
II-C-8
-------
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II-C-9
-------
REFERENCES
Davis, S.N., and DeWiest, R.J.M. 1966. Hydrogeology. John Wiley and Sons,
Inc.
Debney, A.G.P. 1978. Remote sensing detects groundwater in England. Water and
Sewage Works, April.
Dobrin, M.G. 1976. Introduction to geophysical prospecting. McGraw-Hill, New
York, editor.
Holz, R.K., editor. 1973. The surveillant science: Remote sensing of the
environment. Houghton Mifflin Company, Boston.
Holmquist, K.W., and F.L. Scarpace. 1977. The use of satellite imagery for
lake classification in Wisconsin. Technical Report WIS WRC 77-08. Water
Resources Center, University of Wisconsin.
Hundemann, A.S. 1979. Remote sensing applied to environmental pollution detec-
tion and management (a bibliography with abstracts). NTIS/PS-76/0500.
National Technical Information Service, Springfield VA.
Koerner, R.M., U.S. Reif, and M.U. Burlingame. 1978. Detection methods for
location of subsurface water and seepage prior to grouting. American
Society of Engineers, Preprint 3301.
Slonecker, T. 1980. Septic systems analysis. Bucks County, Pennsylvania.
Chalfont-New Britain E.I.S. Buckingham E.I.S. Volume 1, U.S. EPA
TS-PIC-0035.
Taylor, J.I., and R.W. Stingelin. 1969. Infrared imaging for water resources
studies. Journal of the Hydraulics Division. Proceedings of the American
Society of Civil Engineers. 95 (HYI):175-189.
Walton, W.C. 1970. Groundwater Resource Evaluation. McGraw-Hill, Inc.
II-C-10
-------
D. SEPTIC LEACHATE DETECTOR RESEARCH
1. INTRODUCTION
The Septic Leachate Detector (SLD) is an instrument that is capable of
detecting effluents of septic tanks systems by responding to a combination of
conductivity changes and fluorescence. An SLD was used on 35 mid-western
lakes during preparation of the Seven Rural Lakes Area EIS's. The results of
shoreline scans with the SLD and concurrent water sampling for nutrient and
bacteriological analysis constituted one of several data inputs to alternative
development and decision making for those EIS's.
The original shoreline scans and sample preparation were designed to
locate sources of actual or potential nutrient inputs and bacteriological
contamination. While these surveys accomplished their purpose quite
adequately for the level of decision making they supported, review of the
survey methods, instrument operation and the data raised questions about use
of the information generated. Generally stated the questions were:
• Does the instrument detect all effluent sources?
• Does it give positive readings for non-wastewater sources of fluores-
cent materials or dissolved solids?
• Can the SLD be used alone to quantify nutrient inputs to lakes from
septic tanks systems?
• If the instrument cannot be used alone to quantify nutrient inputs,
can it be used with other techniques to do so economically?
Two field trips and several laboratory studies were sponsored by U.S. EPA
Region V to address these questions. This report describes the SLD used in
these efforts and describes the work conducted to address them.
2. DESCRIPTION OF THE INSTRUMENT AND THEORY OF OPERATION
The SLD used is an ENDECO (Environmental Devices Corporation, Marion,
Massachusetts) Typ,e^ 2100 Septic Leachate Detector System, also referred to as
the Septic Snooper . It is protected by U.S. Patent Number 4,112,741.
The instrument and its theory of operation are described by excerpts from
the manufacturer's operation manual (ENDECO, 1980):
The ENDECO Type 2100 Septic Leachate Detector System is a portable
field instructment that monitors two parameters, fluorescence (organic
channel) and conductivity (inorganic channel). The system is based on a
stable relationship between fluorescence and conductivity in typical
leachate outfalls. Readings for each channel appear visually on panel
meters while the information is recorded on a self-contained strip chart
recorder. Recording modes are selectable between individual channel
outputs or a combined output. The combined output is the arithmetic
result of an analog computer circuit that sums the two channels and
compares the resultant signal against the background to which the instru-
ment was calibrated. The resultant output is expressed as a percentage
II-D-1
-------
of the background. Also, the combined recorded output is automatically
adjusted for slow background changes. The system can be operated from a
small boat enabling an operator to continuously scan an expansive shore-
line at walking pace and, through real time feedback, effectively limit
the need for discrete grab samples to areas showing high probability of
effluent leaching. Expensive laboratory time for detailed nutrient
analysis is greatly reduced while survey accuracy is increased sub-
stantially.
...The unit [is] powered by a standard 12-Volt automotive battery.
The plug-in, flow-through conductivity cell is in series with the fluoro-
meter. The probe/wand houses a marine-type centrifugal pump. Discrete
samples may be drawn directly from the instrument discharge for sub-
sequent laboratory analysis....
...Wastewater effluent contains a mixture of near UV florescent
organics derived from whiteners, surfactants and natural degradation
products that are persistent under the combined conditions of low oxygen
and darkness...
Aged effluent percolating through sandy loan soil under anaerobic
conditions reaches a stable ratio between the organic content and chlo-
rides which are highly mobile anions. The stable ratio (cojoint signal)
between fluorescence and conductivity allows ready detection of leachate
plumes by their conservative tracers as an early warning of potential
nutrient break-throughs or public health problems.
The Septic Leachate Detector System consists of the subsurface
probe, the water intake system, the logic analyzer control unit, panel
meters and the strip chart recorder....
The probe/wand is submerged along the shoreline. Background water
plus groundwater seeping through the shore bottom is drawn into the
subsurface intake of the probe and is lifted upwards to the analyzer unit
by a battery operated, submersible pump.
Upon entering the analyzer unit the solution first passes through
the fluorometer's optical chamber where a continuous measurement is made
of the solution's narrow band response to UV excitation. The solution
then flows through a conductivity measurement cell. An electrode-type
conductivity/thermistor probe continuously determines the solution's
conductivity. The solution exits the conductivity cell directly to the
discharge where discrete samples may be collected if indicated by the
response of the leachate detector. Both parameters are continuously
displayed on separate panel meters. Zero controls are provided for both
parameters (organic and inorganic) to enable "dialing out" the background
characteristics to provide maximum sensitivity, as well as enhancing the
response caused by a suspected abnormality. Span Controls are also
provided to control the sensitivity of each parameter separately during
instrument calibration. This is helpful in determining relative concen-
trations of leachate outfalls.
The signals generated and displayed on the panel meters are also
sent to an arithmetic/comparator analog computer circuit designed to
detect changes in the ratio of organics and inorganics typical of septic
II-D-2
-------
leachate. The output of this circuitry is recorded continuously on a
strip chart and is the key indicator of a suspected leachate outfall.
However, isolated increased in either parameter may be cause for concern
and should be sampled for analysis for other potential forms of nutrient
pollution.
The operation manual does not reveal the type of light filters used in
the instruments' fluorometer. Since the spectral characteristics of filters
are crucial to answering some of this report's questions, the filter types and
key characteristics are presented in Table II-D-1. The filter's responses to
various wavelengths are shown in Figure II.D.I.
TABLE II-D-1. SPECTRAL CHARACTERISTICS OF FLUOROMETER LIGHT FILTERS IN
ENDECO MODEL 2100 SEPTIC LEACHATE DETECTOR
Excitation Minimum Peak Maximum % Transmittance
filter Wavelength Wavelength Wavelength at Peak Wavelength
Filter A 320 nm 360 nm 390 nm 35%
Emission Filters
Filter B
Filter C
Filters B + C
400 nm
385 nm
410 nm
500 nm
430 nm
435 nm
_
490 nm
490 nm
90% at 550
46%
38%
3. CHEMISTRY AND FLORESCENCE OF BRIGHTENERS, DETERGENTS, AND
NATURAL ORGANIC COMPOUNDS
a. Brighteners
Brighters and whiteners are chemicals added to cleaning products to
improve the apparent "whiteness" of fabrics. The energy of incandescent light
bulbs is typically deficient in the shorter (blue) wavelengths. This causes
fabrics to seem yellower than they would be in sunlight. The blue wavelengths
reflected by fabrics are artificially augmented by brighteners and whiteners
which absorb invisible ultraviolet light, then release this energy by
fluorescing at blue wavelengths.
During clothes washing these fluorescent chemicals absorb to the surface
of fabric fibers. Fabrics are made of both natural and synthetic fibers which
have a wide range of surface characteristics. There are a variety of fluores-
cent chemicals designed to absorb onto different fabrics. The American
Society for Testing and Materials groups the commercial whiteners into five
classes by molecular structure. Figure II.D.2 reproduces the chemical
structure of the classes. (ASTM, 1976).
II-D-3
-------
% TRANSMISSIONS
GO
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O
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II-D-4
-------
Figure II0D.20 Chemical Structures of Five
Classes ot Fluorescent Whitening Agents (.trom A5TM, 1976)
C COUMARIN
2
R3~T~ c « o
w
DASC DIAM1NOSTILBENEDISULFONIC ACID-CYANURIC CHLORIDE
\
C = N
N
X
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C - N
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rr +
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DSBP DISTYRYLSIPHENYL
, etc.
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T
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- C
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II-D-5
-------
Samples of pure whiteners were requested from manufacturers. Nine
samples were received. Each of the five classes was represented. Absorption
and fluorescence spectra of the samples in dilute aqueons solution were
recorded using an Aminco-Bowman spectrophotofluorometer. Table II-D-2 pre-
sents relevant data. The samples are listed in order of their fluorescence
peak wavelengths.
Table II-D-2 includes the transmission characteristics of the excitation
and emission filters in the SLD. It can be seen that all of the whiteners
except DSBP-1 and the second unlisted one (suspected of being Type C) will
strongly absorb the light passed by the excitation filter. The excitation
spectra of DSBP-1 and the second unlisted sample do overlap the wavelengths
passed by the filter but not as completely as the spectra of the other
whiteners. All of the samples fluoresce strongly in the wavelengths passed
by the excitation filter.
b. Detergents
A number of commercially available cleaning products were acquired.
Dilute solutions of the products were tested with the SLD for fluorescence.
Samples were also analyzed for their absorption and fluorescence spectra with
an Aminco-Bowman Spectrophoto fluorometer.
Spectral characteristics of cleaning products analyzed by spectrophoto-
fluorometer are listed in Table II-D-3. Recorder tracing of the absorbance
and fluorescence responses are provided in Appendix A.
Comparing the absorbance of these products with the spectral characteris-
tics of the SLD's excitation filter (Table II-D-1), it can be seen that the
peak absorbance of all these products are at lower wavelengths than the trans-
mission peak of the filter, 360 nm. However, in all but four of the products,
the overlap between filter transmission and absorbance is probably sufficient
to mitigate fluorescence. The excepts include two fabric softeners (Sta-Puff
and Downy) which absorb at low wavelengths and a cleanser (Ajax) and a liquid
dish detergent (Ivory) which absorb weakly at any wavelength.
Comparing fluorescence of these products with the spectral characteris-
tics of the SLD's emission fliters, the peak fluorescence of the products fall
below the transmission peak of the filters, 435 nm, but overlap is good except
for the cleanser which fluoresces very weakly.
The fluorescence of these cleaning products is presumed to be caused
chiefly, if not totally, by added brighteners. The detergent ingredients may
fluoresce weakly but at wavelengths below the lower transmission threshold of
the SLD's emission filters, 410 nm. Figure II-D.3 illustrates the fluore-
scence of a common detergent without brighteners.
While detergents do not themselves fluoresce, they can substantially
improve the fluorescence of some materials which have a low quantum yield
(proportion of absorbed light energy that is given off as fluorescence). The
detergents do this by forming molecular aggregates, called micelles, around
the fluorescing material. Micelles act liks a shield, preventing contacts
between the fluorescent material and other dissolved chemicals. This reduces
the amount of absorbed light that may be transferred by non-fluorescing
II-D-6
-------
TABLE II-D-2. ABSORPTION AND FLUORESCENCE CHARACTERISTICS OF WHITENER. SAMPLES
(wavelengths in nannometers)
ASTM Type
Designation of
Sample
DSBP-1
Unlisted
DASC-3
DASC-4
NTS-1
P-l
C-l
C-2
Unlisted
SLD Filters'
Transmittance
Absorbance
min.
368
280
<
288
<
284
<
271
271
267
<
280
<
280
391
320
peak(s
387
320
384
311
370(D)
315
370(D)
357
360
331
395
336
407
322
420
360
) max.
416
<
421
<
421
<
412
424
448b
<
439
<
448
360U
448b
390
Fluorescence
min.
b
368b
<
370b
<
368
<
#63
368
<
395
395
395
410
peak(s)
408
391
410 (D)
391
410 (D)
393
410(D)
425
434(D)
460
441
444
448
435
max.
571
<
553
<
536
<
525
571
<
563
579
563
554
490
j* - As identified by ASTM,
Recording not complete.
< - Spectra associated with
D - Dominant peak.
1976. See Figure II. D. 2.
Values presented are approximations.
peaks substantially overlap.
II-D-7
-------
TABLE II-D-3. ABSORBANCE AND FLUORESCENCE CHARACTERISTICS OF DETERGENT
SAMPLES (wavelengths in nannometers)
Cleaning
Product
Final Touch
Wisk
Arm & Hammer
Borateem
Joy
Ajax
Downy
Ivory
Fab
Tide
Clorox 2
Fresh Start
All
Palmolive
Yes
Trend
ERA
Woolite
Sta-Puff
Ivory Snow
Bold 3
Cheer
rain.
275
290
275
275
275
Absorbauce
peak(s)
325
350
332
345
350
No distinct peaks.
260
Several
230 to
275
275
275
290
260
275
290
275
280
280
200
260
260
275
305
small peaks
380
338
338
340
355
341
332
345
355
335
335
356
240
305
350
330
350
335
Fluorescence
max.
380*
395
380*
380*
390
Weak response.
330
from
380*
380*
370
395*
380*
380*
400
380*
396
395
335
380&
360*
380*
rain.
380*
375*
38-*
380*
390
350
370 weak
430 weak
380*
380*
380
365
380*
380*
360
380*
380
360
350
390
380*
380*
peak(s)
420
425
410
418
430
380
response
response
410
416
395
415
412
405
390
417
475
385
405
418
418
428
380
400
425
410
410
max.
525*
560
525
530
530
500
530
530
530
530
530
560
530
530
530
560
475
530*
560
530
-------
Figure II.D.3. Absorbance and Fluorescence__of._Dodecylbenzene__Stil.fonat.e
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mechanisms. Thus, in sufficient concentrations, detergents can increase the
fluorescence of some materials by an order or magnitude (Armstrong et al.,
1981). This "micelle effect" may not be significant with chemicals like
brighteners designed to have high quantum yields. However, it may be signi-
ficant with natural products of organic decompositon as discussed in the next
subsection.
Cleaning product solutions were made up with both distilled water and a
0.03 M solution of a pure detergent, sodium dodecylsulfate (SDS), to be
analyzed by the SLD's fluorometer. The purposes of these measurements were to
verity the SLD's predicted responses and to see if the detergent solution
would demonstrate a micelle effect. Cleaning products were chosen to
represent 1) strong and weak fluorescence responses as indicated by the
spectrophotofluorometer and 2) different types of cleaning compounts.
Solutions were made at approximately 2,500 and 25 parts per million by volume.
(By comparison, one cupful of cleaning product in an average house's waste-
water at 200 gallons/day would be about 300 ppm.) The polarizing filter on
the SLD's fluorometer was set as for the septic tank samples discussed in
Section II.D.4.a.
The names of the cleaning products and the readings are presented in
Table II-D-4. For those solutions that fluoresced, both the meter reading and
the zero adjustment required to bring the meter on scale are reported. Those
solutions which fluoresced so strongly that both zero and span adjustments
together could not bring them on scale, the words "off-scale" arre entered.
As expected, the Ivory liquid dish detergent and the Ajax cleanser showed
negligible responses. At the lower concentration, 25 ppm, only the laundry
detergent and a fabric softener had readings appreciably higher than the water
or soap solution in which they were made. No micelle effect is apparent at
this concentration suggesting either that the quantum yields of their
fluorescing chemicals are high or that the concentrations were just too low.
At 2,500 ppm all products except Ivory and Ajax fluoresced. Most of the
readings were in the range obtained for septic tank samples reported in
Section II.D.4.a. Differences between SDS solutions and H^O solutions were
not consistent. The micelle effect may be responsible for the difference in
Sta-Puf readings. However, the bleach's fluorescence in detergent solution
was actually smaller than in water. The other tree fluorescing products were
about the same in both solutions or were off-scale for both.
These tests indicate that fluorescing chemicals are not present in all
household cleaning products. However, the products with substantial amounts
of fluorescing chemicals, including all of the laundry detergents, can be
detected by the SLD at concentrations equivalent to about one teaspoonful of
product in a residence's daily wastewater.
c. Natural Organic Materials
The possibility that organic materials present naturally in surface water
bodies may produce positive SLD readings is indicated in the manufacturer's
operation manual. Vivid indications of this were witnessed during field
studies on Crooked Lake, Indiana. (See Section II.D.6.) Shoreline scans
detected especially strong fluorescence where streams flow into this lake from
II-D-10
-------
TABLE II-D-4. SLD FLUOROMETER RESPONSES TO SELECTED CLEANING PRODUCTS
Cleaning
Product
Distilled H~0
0.03 M SDS
Ivory Dish Detergent
Ajax Cleanser
Clorox 2 Fabric Bleach
Downy Fabric Softener
Sta-Puf Fabric Softener
Tide Laundry Detergent
Final Touch Fabric
Softener
25
HO solution
Zero
0
0
0
0
0
0
0
0
Meter
11
18
12
17
12
8
24
30
ppm
2500 ppm
SDS solution
Zero
0
0
0
0
0
0
0
0
Meter
46
43
36
40
40
41
38
82
HO solution
Zero
0
0
0
0
Meter
11
22
14
Off-scale
224
53
814
50
50
50
Off-scale
SDS solution
Zero
0
0
0
296
216
266
687
Meter
46
54
37
50
50
50
50
Off-scale
II-D-11
-------
wetlands and in the lake's hypolimnion. The streams were colored light yellow
by soluble decay products from vegetation in the wetlands. Fluorescence of
the hypolimnetic water may also have been from this source or from decaying
vegetation within the lake itself. The lake water was light brown in color.
A sample of the hypolimnetic water was analyzed by an Aminco-Bowman
spectrophotofluorometer to determine how its spectral characteristics compared
with the brighteners and cleaning products. Curve I in Figure II.D.4 shows
the absorbance and fluorescence spectra of the lake water. Its absorbance and
fluorescence characteristics are:
Absorbance Fluorescence
mm. peak max. mm. peak max.
280 340 375» 375- 416 550
These values are characteristic of the cleaning products discussed above.
In fact, had it not been for the color of the hypolimnion water and the field
observation that the entire hypolimnion produced very strong SLD readings, the
spectral scan alone would suggest that this was a detergent sample.
The result of the micelle effect on the fluorescence of this sample is
dramatic as illustrated by Curve II of Figure II.D.4. At a photomultiplier
tube voltage of approximately one-third that of Curve I (M.M. = .003 vs. M.M.
= .001 for Curve I), the intensity of fluorescence is 2.7 times greater. The
overall enhancement is an eight-fold increase. This finding presents the
possibility that the SLD may respond positively, not only to actual increases
in concentrations of fluorescent materials, but also to constant concentra-
tions, the fluorescence of which is enhanced by detergents present in suf-
ficient amounts to form micelles.
To further explore the fluorescence characteristics of organic materials
that might be present in surface waters, laboratory grade tannic acid, humic
acid and a lignosulfonate were analyzed with the spectrophotofluorometer.
Their spectral characteristics are presented in Table II-D-5.
It can be seen by comparison with Table II-D-1 that humic acid and tannic
acid absorb and fluoresce strongly in the wavelengths at which the SLD oper-
ates. Overlap with the lignosalfonate is not as complete but is probably
sufficient for the SLD to detect this and similar materials.
To determine whether the micelle effect intensified the fluorescence of
these laboratory grade organics, an experiment similiar to that performed with
Crooked Lake water was conducted with tannic acid. Figure II.D.5 shows the
result. The detergent caused a nine-fold gain in fluorescence.
d. Separation of Brighteners and Natural Organics
To investigate the feasibility of identifying which substanc-
es in septic tank effluents fluoresce, the mobility of various
brighteners and organic materials was determined by thin layer
chromatography. Nine brighteners tannic acid, humic acid, and
lignosulfonate were separately spotted on both alumina (polar)
and Whatman KC18F (non-polor) plates. The mobile phase used
II-D-12
-------
Figure II.D.40 Absorbance and Fluorescence ot Crooked Lake
Hypolimnion Waste With and Without Added Detergent
o
I,— I
kr
01
4-1
CO
3
CD "
i-H
>v
O
0) .
. 6 _.
ro .
X
W
'-I.
•H
T3
O
CO -
II-D-13
-------
TABLE II-D-5. ABSORPTION AND FLUORESCENCE CHARACTERISTICS OF SELECTED ORGANIC
MATERIALS (wavelengths in narmometers)
Organic
Material
Humic Acid
Tannic Acid
Poly H
(lignosulfonate)
min.
280
310
270
Absorbance
peak max.
360 430
352 400*
310 325*
Fluorescence
min.
410*
380*
325*
peak
465
432
345
max.
580
550
550
* Spectra not complete due to overlap.
II-D-14
-------
Figure IIoD.5, Absorbance and Fluorescence of Tannic Acid
: '.With and Without Added Detergent1
o
o
o
vO
CM
C/3 ^^ /""""s
£§£
! ^
-1
l
CM CM
m en
X 6
W W
II-D-15
-------
on both plates was a 60:40 mixture of methanol and water. The resulting spots
were located by a black light UV source and traced on a transparent overlay.
Figures II.D.6 and II.D.7 reproduce these tracings.
Two interesting conclusions can be drawn from these results. First, the
mobility of the brighteners differs significantly from that of the organic
materials and thereby these substances can be distinguished. The organic
materials are non-polar and thus are immobile on the polar solid phase
(alumina) but are highly mobile on the non-polar solid phase. In contrast,
the brighteners are mobile on both solid phases.
Second, seven of the nine brighteners separated into two or more spots on
one or both solid phases. The two brighteners that did not separate, NTS and
DSBP groups, were also the only samples to have single absorption peaks and
single fluorescence peaks (see Table II-D-2). The samples that separated
evidently were mixtures, all of the components of which may not belong to the
identified brightener group.
The success of this experiment in distinguishing between laboratory grade
brighteners and the other organic materials suggested thin layer chromato-
graphy as an appropriate tool for studying fluorescent materials in septic
tank effluent as reported in the next section.
e. Discussion
These studies suggest at least four causes of the localized increased in
fluorescence to which the SLD might respond:
1) brighteners from cleaning products which flow or leach from on-site
systems into surface waters,
2) naturally occuring organic materials released from decomposing
vegetation,
3) organic materials released from decomposing- human feces and kitchen
wastes, both of which have substantial contents of plant material,
and
4) increases in fluorescence of any of these materials by means of the
micelle effect when sufficient concentrations of detergent are
present.
For the practical purpose of locating wastewater or leachate discharges
into surface waters, these several potentially interactive sources of
localized fluorescence increase do not prohibit meaningful interpretation.
Three of the sources are related to wastewater. The naturally occuring
organic materials may usually be distingued by their broader spatial distri-
bution and their coincidence with natural features such as inflowing streams,
wetlands, and thermal layers in lakes.
Supposedly the SLD's second recording channel, conductivity, along with
its integrated circuit would distinguish between the natural and wastewater
sources.
II-D-16
-------
Figure II-D-6.
STANDARDS
Figure II.D.6. Thin Layer
Chromatography of
Laboratory-grade Organic
Chemicals on Polar Solid Pha:
S. P. = Alumina
M. P. = 60:40 (v:v) methanol: H20
C2
SOLVENT FRONT
c
o
o
CO
o
Q.
i.
O Q
3 00
M_
-------
Figure II-D-7.
S.P. = Whatman KC18F
M.P. = 60:40 (v:v) methanol:
STANDARDS
Figure II.D.7. Thin Layer
Chromatography of Laboratoi
grade Organic Chemicals on
Non-polar Solid Phase
SOLVENT FRONT
UASC-GROUP
00
Q_
O
Q
oo
o;
o
Q
_J
UJ
s
O
_J
00
Q_
O
Qi
ZD
Q_
Q-
O
CQ
oo
Q.
O
DASCBP NTS
n i i
'll
Q-
O
CQ
U_
LU
.O
Q_
O
O
CM
X
CQ
&
D_
O
SSI
'$?
1 1 — — 1 \
J
1 —
— 1 \ —
— T 1 — '\ «T
= main "brightener" spot
II-D-18
-------
4. CHARACTERISTICS OF SEPTIC TANK EFFLUENTS
Early and still the most popular explanations of the SLD's theory of
operation emphasized the role of brighteners as the detected material. The
possibility of having harmful levels of nutrients or bacteria in effluents or
leachates but not fluorescent materials was stirred by this emphasis. To
address this possibility as well as to assess the correlations of fluorescence
with other chemical parameters of interest, 35 samples were collected from
septic tanks in the vicinities of Cincinnati, Ohio, and Alanson, Michigan.
The tests performed on these samples and results are discussed below.
a. Chemistry and SLD Fluorescence
Septic tank samples were collected by commercial septage haulers during
pumping operations requested by owners of the septic systems. Haulers were
requested to collect samples from the liquid layer in tanks so as to approxi-
mate septic tank effluent as much as possible. Tha appearance of the col-
lected samples suggested that the haulers were unsuccessful at minimizing
collection of settled or floating solids. The samples are considered to be
septage, therefore, not effluent.
Samples were tested without filtering for nitrate, nitrite, and total
Kjeldahl nitrogen, total phosphorus and methylene blue active substances by
the following methods:
EPA Reference
Parameter Method Number*
NO -N 352.1
NO^-N 354.1
Total Kjeldahl Nitrogen 351.4
Total Phosephorus 365.3
Methylene Blue 425.1
Active Substances
-v "Methods for Chemical Analysis of Water and Wastes."
1979. U.S. EPA, Cincinnati, Ohio. EPA 600/479-020.
Subsamples were filtered through glass fiber filters for analysis by the
SLD. Four milliliters of each sample were composited to make a reference
solution for instrument calibration. Conductivity of the reference solution
and 24 individual septic tank samples was too high for measurement by the SLD.
Conductivity measurements for the remaining 11 individual samples ranged
widely requiring the full range of both span and zero meter adjustments.
Units reported for the inorganic channel readings are combined from these two
meter adjustments by the following formula:
I = 2,000 - I50S + I5QZ
where:
I = inorganic channel reading in relative units
II-D-19
-------
ICQS = span reading when the meter is adjusted to read 50
Ic-flZ = zero reading when the meter is adjusted to read 50.
It has not been determined whether I increases linearly with conductivity.
With two exceptions, samples 16 and 24, organic channel readings could be
taken from the zero adjustment necessary to bring the meter to a fixed point
(50). All other samples fell into the scale of 26 to 1,000 units on the zero
adjustment. Fluorescence is reported in these relative units. The reference
solution was used to set the fluorometer1s polarizing filter such that organic
channel span and zero adjustments of 500 would produce a meter reading of 50.
Results of these tests are presented in Table II-D-6. Concentrations of
nitrate and nitrite nitrogen were very low, reflecting the anaerobic state of
the samples. Concentrations of total Kjeldahl nitrogen and total phosphorus
in these unfiltered samples were substantially higher than average values for
septic tank effluent of 10-16 mg/L.-P reported in the literature. This is due
to excessive solids in some samples related to the manner of collection.
To assess the correlation between these parameters, linear regression
analysis was performed between pairs of parameters. Nitrate and nitrate
nitrogen were not included. Table II-D-7 lists the correlation coefficients,
slopes, and y-intercepts calculated for the pairs.
Correlations between parameters in the first four pairs are very high
with degrees of certainty above 99.9%. However, three of the four pairs that
include fluorescence (organic channel on the SLD) have a degree of certainty
below 90%. The weaker correlations may have resulted from the fact that SLD
tests used filtered samples whereas chemical analyses were run on unfiltered
samples.
Of particular note is the degree of certainty of the correlation between
the organic and inorganic channel readings. At approximately 85% degree of
certainty, this weak correlation throws into question the manufacturer's
suggestion that there is a stable ratio ("cojoint signal") between fluore-
scence and conductivity, and that the SLD can be calibrated to this ratio as a
means of measuring strength of wastewater present in surface waters. The data
presented here, however, is not sufficient to disprove this part of the
manufacturer's theory of operation.
b. Thin Layer Chromatography
Eighteen subsamples of filtered septic tank samples were analyzed by thin
layer chromotography using polar and non-polar solid phases with a methanol/
water mobile phases as described above in Section II.D.S.d for laboratory
chemicals. Subsamples were concentrated approximately 20 times by vacuum
evaporation before being spotted on the plates.
Results of the tests on the alumina solid phase are shown in Figure
II.D.8 and II.D.9. Figures II.D.10 and II.D.ll show the results on the
non-polar solid phase.
II-D-20
-------
TABLE II-D-6. CHEMICAL AND SLD ANALYSIS OF SEPTIC TANK SAMPLES
Sample
Number
6
7
8
9
10
11
12
13
14
15
16
17
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
41
42
43
44
45
46
47
NO -N
(mg^N/1)
0.026
<0.05
0.18
<0.05
0.07
<0.05
<0.05
<0.05
0.18
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
NO -N
(mg-N/1)
<0.05
<0.05
<0.05
0.76
<0.05
0.06
<0.05
<0.05
<0.05
<0.05
0.22
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
TKN
(mg-N/1)
85.0
75.0
127.
103.
163.
163.
185.
200.
270.
127.
228.
140.
190.
110.
85.0
152.
152.
163.
128.
153.
190.
125.
130.
136.
500.
62.0
123.
100.
33.8
55.0
47.5
49.0
107.
16.0
48.0
TP
(rag-P/1)
6.66
7.06
26.2
18.7
29.9
29.1
27.0
25.1
47.1
25.7
87.0
16.3
8.30
36.3
35.0
34.4
35.4
30.0
34.7
35.5
34.4
31.3
31.0
23.4
540.
11.5
58.2
28.0
61.1
12.8
12.6
13.9
14.2
13.8
8.40
MBAS
(mg/1)
4.24
3.97
5.77
7.22
5.14
1.80
3.05
4.93
2.01
8.69
5.34
2.84
1.18
1.14
1.81
1.74
2.13
3.38
2.80
0.676
0.578
3.00
3.08
2.83
20.4
0.40
5.56
8.48
2.43
0.29
0.90
3.11
1.35
3.41
3.13
SLD
Organic
channel
(relatvie
units)
180
152
633
502
560
574
720
1000
772
630
-
638
-
456
305
608
668
666
660
431
337
808
372
498
808
130
238
619
460
154
98
188
276
98
26
SLD
Inorganic
channel
(relative
units)
968
790
-
-
-
-
-
-
-
-
-
-
-
-
1000
-
-
-
-
-
1950
-
1621
1705
-
-
-
-
-
-
952
1786
1468
1820
836
- = Off-scale.
II-D-21
-------
TABLE II-D-7. LINEAR REGRESSION ANALYSIS OF CHEMICAL AND SLD DATA FOR SEPTIC
TANK SAMPLES
Parameters
Correlation
Coefficient
Slope
Y-Intercept
TP MBAS
TKN TP
Organic TKN
TKN MBAS
Organic Inorganic
Organic MBAS
Organic TP
.806
.788
.677
.618
.505
.293
.267
.033
.814
.207
.026
1.60
.0038
.084
2.269
-67.0
30.88
.152
986
1.8067
1.73
II-D-22
-------
Figure II-D-8.
S.P. = Alumina M.P. = 60:40 (v:v)
methanol :H.20
Figure II.Do8. Thin Layer
Chromatography of Septic Tank
Samples on Polar Solid Phase
v".
W
SOLVENT FRONT
.-•••••• •. .'.
• • " *
* .•- •
;"•
.'.
"/
..'
::/
P*&
857-
1046,
Fil
\
* ^t
. « * 1
, ' \
f
* t
\ " .
»^»
857-
1045,
Fil
/ft
XbT
857-
1030,
Fil
jSV
857-
1027,
Fil
. . •
*-tt?
857-
1026,
Fil
.AC
857-
1042,
Fil
•>!A*^
857-
1031,
Fil
44*+
851-
1035,
Fil
'fCk
857-
1025,
Fil
Almost all material remained at oriqin.
spots were very very light!
H-D-23
Other
-------
Figure II-D-9.
S.P. = Alumina
M.P. = 60:40 (v:v) methanol: H90
Figure II.D.9. Thin Layer Chromatography
Septic Tank Samples on Non-Polar Solid Phi
SOLVENT FRONT
857-
1044,
Fil
857-
1046,
857-
1034,
Fil
857-
1043,
Fil
857-
1043,
857-
1028,
Fil
857-
1033,
Fil
857-
1029,
Fil
857-
1032,
Fil
857-
1024,
Fil
Almost all material remained at origin.
II-D-24
-------
Figure II-D-10.
S.P. = Whatman KC18F, reverse phase
M.P. = 60:40 (v:v) methanal: H20
Figure II.D.10. Thin Layer
Chromatography of Septic Ta
Samples on Non-Polar Solid
Phase
SOLVENT FRONT
1
857-
1046,
Fil
I
857-
1045,
Fil
1
857-
1030,
Fil
i
857-
1027,
Fil
I
857-
1026,
Fil
i
857-
1042,
Fil
i
857-
1031,
Fil
I
857-
1035,
Fil
t
857-
1025
Fil
II-D-25
-------
Figure II-D-11.
S.P. = Whatman KC18F, reverse phase
M.P. = 60:40 (v:v) methanol:H20
Figure II0D011. Thin Layer
Chromatography of Septic Tank
Samples on Non-Polar Solid Phas
SOLVENT FRONT
1
857-
1044,
Fil
I
857-
1046,
i
857-
1034,
Fil
1
857-
1043,
Fil
i-
857-
1043,
i
857-
1028,
Fil
1
857-
1033,
Fil
i
857-
1029,
Fil
i
857-
1032,
Fil
•
857-
1024,
Fil
Almost all material goes with the solvent front.
II-D-26
-------
A large proportion of each sample behaved like non-polar organic
materials and are suspected of being soluble decomposition products of feces
and food wastes.
With two exceptions, the amount of fluorescent material that migrated at
all like the brighteners was very small and close to being undetectable by
visual inspection under black light. By contrast the spots that moved with
the solvent front (non-polar solid phase) and that stayed at the origin (polar
solid phase) were visible with the unaided eye and were dark brown under black
light.
Brighteners are suspected of being the source of faint spots seen in
intermediate positions on the polar solid phase. Their intensity and their
similarity to the mobility of pure brighteners is great in only two samples.
One of the nineteen samples produced no brightener-like spots.
This information strongly suggests that brighteners play only a minor
role in the fluorescence of anaerobically treated domestic wastewater.
c. Absorption and Fluorescence
Eighteen of the subsamples analyzed by thin layer chromatography were
also analyzed by spectrophotofluorometer. The absorption and fluorescence
characteristics of all samples were surprisingly similiar. Absorption peak
wavelengths fell within the range of 320 to 340 nannometers. Fluorescence
peak wavelengths fell within the range of 385 to 400 nannometers. Minimum
absorbance was at approximately 200 nannometers for all samples and maximum
fluorescence at 575 nannometers. Figure II.D.12 illustrates a typical
recording.
The fluorescence scans of these samples were continued through the entire
range of visible light. The purpose for doing this was to seek fluorescence
at higher wavelengths which might be used to identify wastewater without the
interference of naturally occurring organic materials. The small peak between
600 and 700 nm in Figure II.D.13 is typical of the long wave length response
from the samples. This peak was initially though to be fluorescence. How-
ever, additional testing showed 1) that the peak disappeared when the sample
was filtered (see Figure II.D.13) and 2) that excitation at increasingly
higher wavelengths shifted this peak to higher wavelengths (see Figure
II.D.14). It was concluded that the 600-700 nm peak was due not to fluores-
cence but to harmonic effects of light scattered by colloidal material left in
the samples after the preparatory filtering through glass fiber filters.
Indeed, the peaks of these harmonic responses were all twice the excitation
wavelengths.
d. Stability of Fluorescence
Knowledge of the effect of time on the fluorescence of materials in
wastewater could be helpful in interpreting fluorescence data from wells or
other water resources where time of travel is long. Five filtered septic tank
samples that had been stored in opaque containers at room temperatures for
three years were measured using the SLD as calibrated for the samples dis-
cussed above. Three of the samples had readings of 526,990 and 1,000 and two
were off-scale (high). These readings were high compared to the 500 reading
for the composite sample used to calibrate the fluorometer.
II-D-27
-------
o-
H—- I-
•™r—r
. : .1
!-—-f \—.^\
! iii • SC!
-A-
II-D-28
-------
fa
II-D-29
-------
L l_ _ ;_ j __ ,
II-D-30
-------
These higher readings could be due to any of several factors such as
source of wastewater or concentration overtime by evaporation. However, the
fact that any fluorescence was detected of all indicates that the material
which fluoresce are quite stable. Since no attempts were made to sterilize
the old samples, it appears that these materials are not subject to bacteria
degradation.
5. SOIL COLUMN STUDIES
An attempt was made to measure the passage or orthophosphate, ammonia
nitrogen, nitrate nitrogen and detergent whiteners simultaneously through soil
columns under saturated conditions. The purpose of this work was to compare
the mobility of major nutrients through soils relative to detergent whiteners.
Sandy, sandy clay loan and peat soils were collected from sites near
glacial lakes in the midwest. Soils were packed in Plexiglass tubes 5 cm
inside diameter by 65 cm length. The sandy clay loam and peat soil turned out
to be insufficiently permeable to acquire sufficient volumes of permeate for
complete analysis. Therefore, two sand columns were set up and one column was
set up with 75% sand soil mixed with 25% of the sandy clay loam.
Columns were fed artificial effluent and dilution water. Based on
analysis of major ions in groundwater collected at the soil sampling sites,
the dilution water was made of distilled water plus calcium, sodium and
magnesium salts to approximate the ionic strength of the groundwater. The
effluents were made up to have total dissolved solids concentrations approxi-
mately 500 mg/L in excess of the groundwater. The extra ions were added as
salts of sodium plus ammonium nitrate. A commercial detergent was hydrolized
in weak acid to provide orthophosphate and fluorescent material. Sufficient
detergent was used to produce an orthophosphate concentration similiar to what
is typical of domestic wastewaters, 12 mg/L-P.
Effluent solution alone was passed through Sand Column #1 for three and
on-half hours until breakthrough of orthophosphate, nitrate and ammonia were
apparent. Then dilution water alone was passed through the column for seven
more days to trace the wash-out of nutrients and fluorescent materials. The
data for Sand Column //I are presented in Table II-D-8. Ammonia and nitrate
concentrations and conductivity in the permeate fell rapidly to low, rela-
tively stable levels within about 12 hours. Phosphorus concentrations fell to
about 1 mg/L after 24 hours and remained at that level for the remainder of
the test. Apparent fluorescence did not reach a peak until 20 hours after
effluent application was ceased, then fell to a low level within 12 hours.
Absorbed fluorescent material may have started leaching out after the third
day as suggested by the increasing fluorescence levels.
Sand Column #2 received mixed effluent and dilution water from start to
finish over the same eight day period. The ratio of dilution water to
effluent was not carefully measured but is estimated to be 10:1 to 5:1.
Nutrients and fluorescence in the permeate from this column reached a somewhat
erratic equilibrium within 24 hours as shown in Table II.D.9. Fluctuations in
all parameters was probably due to varying ratios of feed solutions resulting
from differentially falling lead losses in feed bottles.
II-D-31
-------
TABLE II-D-8. SAND COLUMN #1 - PERMEATE DATA
Date
15 July
16 July
17 July
19 July
20 July
22 July
Time PO,
2:00 p.m. 0
2:20 0
2:25 0
2:40 .74
3:05 .77
3:27 .85
3:50 .15
4:10 1.1
4:40 1.5
5:30 4.7
8:00
11:00 p.m.
4:50 a.m.
10:00 3.8
8:00
9:00
10:30
11:45 a.m.
12:50 p.m. 1.8
1:55
2:45
3:55
5:00
5:55
6:45 p.m. .6
7:35
8:45
9:50
11:00
11:45 p.m. 1.0
8:00 a.m.
9:50
12:15 p.m.
2:15
3:10 .7
4:00 p.m.
4:30 p.m.
8:45 a.m. 1.0
4:00 p.m.
(mg/L-N) (mg/L-N)
4 4
19 8
26 7
17 7
6 3
6 2
42 10
91 24
115 81
26.52 19.6
31.74
>61.26
2.88
1.86 <
1.98
.96
1.38
.90
1.08 <
.78
.66 <
.36 <
4.32 <
.12 <
Conductivity
167
247
264
205
170
175
197
355
484
301
197
195
192
214
236
200
Fluorescence
(Meter reading)
14
20
22
-
25
26
32
28
46
31
31
29
26
27
39
18
16
19
19
14
13
15
19
16
23
20
22
38
26
II-D-32
-------
TABLE II-D-9. SAND COLUMN #2 - PERMEATE DATA
Date
15 July
16 July
17 July
18 July
19 July
20 July
21 July
22 July
Time PO, NO. NH. Conductivity
434
(mg/L-P) (mg/L-N) (mg/L-N)
5:30 p.m. .4 2.16 168
8:00 p.m.
5:30 a.m.
9:20 1.1 60.48 29.68 354
10:30
11:45
12:50 p.m.
1:55
2:45 6.68 13.75 24.05 237
3:55
5:00
5:55
6:45
7:35 6.70 9.60 6.72 227
8:40
9:50
11:15
8:00 a.m.
12:15 p.m. .4 3.18 < 225
3:10 p.m.
-
2:00 a.m.
5:55 a.m.
5:00 p.m.
11:30 5.8 54.30 8.68 252
4:00 p.m.
4:30 p.m.
4:00 p.m.
8:45 a.m. 8.0 1.08 30.66 241
4:00 p.m.
Fluorescence
(Meter reading)
_
50
26
31
18
32
20
34
47
19
15
19
15
13
13
14
13
41
19
16
20
20
20
21
29
32
42
46
35
II-D-33
-------
Sand and Clay Column #3 was fed solutions like Column #2 but over a
longer period of time since it took much longer to produce ammonia or
phosphorus breakthrough in the permeate as shown in Table II-D-10. Unfor-
tunately only a few fluorescence measurements were taken but these showed a
higher level than either of the two sand columns. This could be due to a
lower dilution water:effluent ratio, to natural fluorescent materials leaching
from the soil to lesser retention on the soil. Unfortunately, insufficient
notes were kept regarding feed rates to confirm or reject that hypothesis. No
control columns were leached with the dilution feed to determine if the solis
themselves produced fluorescent materials. The reason for higher fluorescence
in this column cannot, therefore, be assessed.
6. FIELD INVESTIGATIONS
Surveys of septic tank effluents along shorelines were conducted pre-
viously in seven study areas examined by Region V. Taken together those
surveys located few effluent plumes relative to the number of lakeshore
dwellings. One major lake, Otter Tail Lake, Minnesota, was surveyed twice
with radical differences in the number of plumes identified (K-V Associates,
1979a and b). Information provided by the surveyor, Dr. William Kerfoot, also
suggested that the emergence of effluent plumes into lake waters is a dynamic
process. Variability in groundwater flow, changing wind and water currents,
and seasonal use of dwellings were all recognized as influencing how
detectable plumes might be and whether they might even appear and disappear
intermittently.
The low number of plumes detected in some lakes raised questions about
the location of plume emergence. Surveys were conducted as close to shore-
lines as possible assuming that effluents flow with an unconfined water table
to the lakeshore. However, it clay lenses or other continuing layers inter-
vened, effluent could emerge away from shore or at other unexpected locations.
To address these concerns and to gain operational familiarity with the
equipment, field investigations were conducted from August 26 to September 15,
1980. The site selected for this work was the first and second basins of
Crooked Lake, Indiana. Crooked Lake was chosen because 1) a good data base
had been developed on it during preparation of one of the seven rural lake
environmental impact statements, and 2) the percentage of lakeshore homes with
plumes during previous surveys was especially low.
a. Plume Stability
Two leachate surveys had beem conducted on Crooked Lake and groundwater
flow patterns had been determined (K-V Associates, 1979c and d). Figure
II.D.15 shows the outline of this lake with the plumes located during these
earlier surveys and the groundwater flow information. The December 1978
survey, even though conducted several months after the summer recreation
season, detected more plumes (19) than the subsequent August 1979 survey (4).
To evaluate plume stability during the 1980 field investigations, three
heavily developed shoreline segments facing the main body of the lake were
surveyed on multiple occasions. Segments are illustrated in Figure II.D.16.
During initial scans of these segments only the organic channel's signal was
recorded. Later scans were recorded on the combined mode for comparison.
During all shoreline scans the span adjustments on both channels were set for
maximum response to changes in conductivity and fluorescence.
II-D-34
-------
Figure II0D. 15 Effluent Plumes and Ground water Flow Recorded during Previous Studies
(K-V Associates, 1979 c and d)
t
T
December 1978 - *KE
erupting plume
stream
dormant plume
\
S
AUGUST '1979
CROOKED LAKE
Direction and rate of Groundwater Flow at selected
stations around the Steuben Lakes Shoreline, August 1979
CROOKED LAKE
MILE
5 ft/day
II-D-35
-------
*'ss**'e^r^ J- '-'fK-f^-T
^^fe°'-fcft
>'^,*<^*•;=&&- >i "'/ir3 /^\ r^jr^zf^
* \i$^ >>& I
2 ^f^ldv^.O^,
-'^»5^- -•-•^~i-x5'
-------
TABLE II-D-10. SAND AND CLAY COLUMN #3 - PERMEATE DATA
Date
16 July
17 July
18 July
19 July
20 July
23 July
25 July
27 July
30 July
Time
9:00 a.m.
7:35 p.m.
9:50 a.m.
8:45 a.m.
4:00 p.m.
4:30 p.m.
4:55 p.m.
8:30 a.m.
7:50 p.m.
9:20 a.m.
P04
(mg/L-P)
.4
.4
-
.3
.3
.4
.02
.15
.94
<.05
(rag/L-N)
1.20
.60
6.12
103.68
26.88
55.44
24.48
13.80
1.89
.97
NYY, Conductivity Fluorescence
(mg/L-N) (Meter «»dla»)
<-01 169
<.01 188 58
<.01 226 61
".01 335 49
<.01 244 53
<.01 303
<.01 321
3.20 294
5.04 271
6.05 330
II-D-37
-------
Figure II.D.17 shows where recordings typical of effluent plumes were
obtained within these segments at one time or another during the three week
period. Most of these recordings document very small changes in organic or
combined signals. Examples of the smallest and the largest responses judged
in the field to be attributable to wastewater sources are illustrated in
Figure II.D.18. For comparison, Figure II.D.18 also shows part of a recording
made at a fixed location where no wastewater influence was suspected.
Only 5 of the 25 plumes identified in the three segments were present
during every scan. Logs for each segment and discussion of significant obser-
vations suggest reasons for this.
South Shore, First Basin
Date
Time
Weather
Recording
Channel
Comments
29 Aug.
8:30-9:00 a.m.
2 Sept. 4:50-5:26 p.m.
Very slight
breeze
Strong wind
in morning;
moderate during
scan.
Organic Flat response except
2 distinct peaks.
Organic Flat response except
small peak at a place
recorded 29 Aug.
14 Sept. 10:04-10:30 a.m.
Moderate wind
NNW.
Organic Flat response.
Access to the shoreline was difficult in the middle of this segment due
to a shallow, pebble-paved bottom. Some plumes in this stretch may have been
missed, but none were found on either side where shoreline was easily
accessible.
One of the two plumes was particularly strong during the first scan and
was the only plume detected in the second scan. But it was not detected
during the last scan either because of the wind or because the wastewater
source is a direct discharge. The building was not in use the day of this
last scan.
South Shore, Second Basin
Date
Time
Weather
Recording
Channel
Comments
30 Aug. 8:31-9:25 a.m. Moderate Organic
breeze from
south.
30 Aug. 2:02-3:10 p.m. Slight breeze Combined
Shoreline in the lee
of wind. 7 plumes.
12 plumes. Under
similiar conditions,
the combined mode
located 5 additional
plumes.
II-D-38
-------
fVlSrl ^^
',• *~ ,->. ~,-r\
,^^^^^mi^^ ^«:^3B^r
^r^^^r^-^TT^^^^^/r^^:^: * "^t/tfs^L
&&$^W^^?~t8
•"<^^^:
*. a' r\ ^i^^-^.QT'B '''""- /
^f)^^,^^ ^n
: :$(—^- !«.
"-»
'"O>
? fe^; ^
A
. , -x^'V^W
•rf^ l^^ '^! ^Ii5> .^
^^,^X^ '^X^-^
^e^> |/ C7 /' *
X
W 00
ro c
(JO en
3 T)
ro ro
3 o
rt rr
W ft)
* C-
K>
C^
w
i-h
HI
>
£ ffi
s s
I
1—'
JS
^
I -X>-SX '/ /' /' '
H" yi/'/j'^ '^
1 ''-t^i. ih^-
~ •—^-^i i / ^ - • - f"r'"7 ^
J '^u:^
^. ^
II-D-39
c
fD
w w
ro
o o
rf ffi
CD CT
3 ro
cr o
fD rr
i-l fD
CL
3 H-
00 (T
o zr
> H-
s
-------
Figure II.D. 18 Examples of SLD Responses Smallest Plume, Largest Flume and
Largest Plume Constant Background
!P»
V
l">
o
f>
O
tuti
®
3
II f? , 1,
0
/
a
(
-
, 6
-
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/'
.
IT"
1
\i
•VNC
- f
Ytf
I
.'
•'
1
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/
i;
«\
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•;
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/
i
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1,1
('.
i
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1 !'
t
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j
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1 1
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-
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1 '
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1 ;
i
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1 1 ' '
i ! '
7}
C
if'
V
1 >
*
' 1
j
1 ,
II-D-40
-------
South Shore, Second Basin (continued)
Date
Time
14 Sept. 10:33-11:15 a.m.
Weather
Strong breeze
from north.
Recording
Channel
Organic
Comments
5 plumes detected
despite strong
on-shore breeze.
The morning and afternoon scans on 30 August provided the first of two
planned comparisons between organic channel and combined channel recording.
Figure II.D.19 shows the two recording modes for the same part of this seg-
ment. While the organic channel recording is useful in identifying large-
scale variations in fluorescence that may be due to streams or wetlands, the
combined channel performs rapid data analysis that allows the operator to
devote greater attention to making and recording observations about house
locations, shoreline conditions, weather, etc. The greater number of plumes
detected in the afternoon may have been due either to calmer winds or to
enhanced data display by the combined channel.
The five plumes detected on 14 September were the only ones on Crooked
Lake that were detected during every scan.
North Shore, Second Basin
Date
30 Aug.
14 Sept.
Time
26 Aug. 3:40-4:55 p.m.
Weather
Not recorded
Recording
Channel
Organic
11:08-11:44 a.m.
31 Aug. 5:25-6:33 p.m.
11:45 a.m.-
12:20 p.m.
Moderate breeze Organic
from west.
Very light Organic
breeze from
southwest.
1" rain mid-day.
Strong breeze Organic
from northwest
14 Sept. 12:30-12:55 p.m.
Wind shifting
to west*
Combined
Comments
Two peaks, one abnor-
mally large off of a
lot with construction
activity.
No discernable waste-
water peaks. Wind-
generated waves.
No discernable waste-
water peaks. Heavy
boat waves.
Shoreline on lee,
protected by hills.
High background
fluorescence with
broad variations.
7 plumes.
Many peaks at begin-
ning of scan in lee.
No peaks toward end
of scan out of lee.
II-D-41
-------
Figure II.D.19 Comparison of Organic Channel and Combined Signal Recordings; South Shore,
Second Basin; 30 August
Organic Channel
Combined Signal
II-D-42
-------
North Shore, Second Basin (continued)
Date
14 Sept.
14 Sept.
14 Sept.
Time
12:58-1:21 p.m.
3:29-3:46 p.m.
4:07-4:55 p.m.
14 Sept. 4:55-5:09 p.m.
Weather
Wind shifting
to west.
Recording
Channel
Comments
Combined Similiar to prior
scan.
Moderate breeze Combined Similiar to two
from southwest. previous scans.
Moderate breeze Combined Walking scan getting
from southwest. probe very close to
shore. Fewer and
smaller peaks than
previous scans. Much
lower background
fluorescence than in
morning.
Slight breeze Combined All but 3 peaks
from southwest. disappeared.
The large peak recorded during the 26 August scan was the largest waste-
water source detected during the field investigations. Later discussions with
the occupants of the nearby house revealed that repairs had been made to the
on-site system earlier that day and some of the wastewater may have entered
the lake. This source was not detected during any later scans.
No peaks were identified during scans of this segment 30 and 31 August.
Wind and waves may have dispersed any plumes.
The series of six scans on 14 September produced a considerable amount of
information and raised some interesting problems in interpretation of recorded
data. Large numbers of apparent plumes were detected during the first four
scans in the western two-thirds of this segment. This part of the segment was
protected from strong, steady winds by hills and trees next to the lake. Few
recording peaks were generated outside of this lee. As the wind shifted to
the south and calmed somewhat in late afternoon, the number and intensity of
peaks decreased until very few could be detected by 5 p.m. Also, the level of
background fluorescence decreased in the afternoon necessitating a recalibra-
tion of the organic channel before the next to last scan.
There are two interpretations that can be made of the recordings for this
segment. First, the absence of many plumes during all scans except for the
lee area on the 14th of September could be explained by dispersal of plumes by
waves and wind-generated currents. The emergence of effluent plumes may even
have been induced by a lowered lake elevation on the lee side caused by the
wind which accelerated groundwater, and effluent, flow toward the lake.
Alternatively, the source of fluorescence and conductivity increases may
have been the lake's hypolimnion, raised and disturbed by wind-generated
currents in the epilimnion. The presence of high fluorescence and conduc-
II-D-43
-------
tivity in the hypolimnion was demonstrated by exercises described later in
this section. If this interpretation is valid, there may have been no waste-
water plumes in this segment at all on the 14th. Unfortunately, this possibi-
lity was not recognized until after the opportunity to do verification exer-
cises had passed.
b. Plume Emergence Points
The possibility that effluent plumes might be entering this lake some
distance from shore was investigated by running transects with the SLD per-
pendicular to the shore. To do this a modified probe was constructed with a
1,200 gallon per hour submersible pump and twenty feet of flexible tubing.
The boat was towed by a SCUBA equipped diver who held the probe approximately
one foot above the sediments while swimming toward the center of the lake.
Locations of the transects are shown in Figure II.D.20. These locations
were chosen because 1) groundwater flow was previously determined to be toward
the lake, 2) the shorelines are developed, but 3) few or not effluent plumes
had been detected.
At the end of two transects from the south shore, the direction of tow
turned to follow ledges to check the possibility that the drop-offs might
intersect clay lenses or other confining layers.
No localized increases in fluorescence were detected. Along transects
from the east shore of the First Basins, the organic recordings increased
gradually along the shallow, even grade. Figure II.D.21 reproduces the
recording of the middle transect.
A similar but more dramatic increase was recorded from transects on the
south shore. In particular, the recording for the transect starting at the
point between the two basins went off-scale within 50 feet of shore and 19
feet depth. A similar rapid increase for the transect from the south shore of
the First Basin is also reproduced in Figure II.D.21. Conductivity, which was
noted separately, also increased rapidly at this depth.
The depth where the increases occurred, and improved transparency at this
depth noted by the diver suggested that the signals were not caused by
localized effluent plumes but were characteristic of the lake's hypolimnion.
To check this possibility, the probe was lowered to 20' in deep water
250* off shore in the southwest part of the First Basin, the zero adjustment
for the organic channel was increased to bring the meter back on scale, and
the boat was allowed to drift westward with the wind. Figure II.D.22 repro-
duces part of the recording. The wide, repaid fluctuations suggest that the
probe was skimming in and out of the upper surface of the hypolimnion.
As discussed in Section II.D.3.C. a sample of water drawn from the hypo-
limnion had absorption and fluorescence spectra similiar to laboratory grade
humic acid and tannic acid, suggesting that decaying vegetation in the lake or
in wetlands which drain to the lake was the source of this strong fluore-
scence. The alternative source would be wastewater from shoreline residences.
Indeed, the spectra of septic tank samples are also very similar to those of
the hypolimnion sample.
II-D-44
-------
^1^A<- &$$> H^.^
II-D-45
-------
Figure II0D021 SLD Organic Channel Recordings on Plume Emergence Point Transects
Middle Transect, East Shore,
First Basin
e
3-1 o-
O
a
o
?v
O-12-
o
c
0
G
O-2-
©
c—
South Shore Transect. First Basin
d 1 '
6—
OS
O
<*
G
oho-
oK
^\
'o
')
II-D-46
-------
Figure II.D.22
Fluorescence Response of SLD
to Crooked Lake Hypolimnion
H-D-47
-------
The diving transects, instead of demonstrating alternative routes for
effluent migration and discovering why so few plumes are detectable around
Crooked Lake, revealed a massive reservior of strongly fluorescent water, the
source of which may have nothing to do with wastewater or shoreline devel-
opment .
c. Stream Plumes
The SLD surveys conducted in support of the seven Rural Lake EIS's,
including the two surveys on Crooked Lake, detected increased conductivity and
fluorescence in streams where they flowed into the lake. Shoreline scans
during the 1980 field investigations also detected plumes caused by Carpenter
Ditch which flows into the southeast corner of the First Basin and the stream
flowing from Loon Lake to enter the First Basin on the south shore just east
of the point dividing the basins. Both streams drain smaller lakes that are
surrounded by wetlands.
The SLD responses to these streams were of greater magnitude than to
suspected effluent plumes. Figure II.D.23 reproduces several recordings
obtained where the Loon Lake stream enters the First Basin. Note that even as
large a source as this can be missed or does not flow some days. These
recordings were made at the same channel adjustment setting as the shoreline
scans illustrated and discussed in Section II.D.6.a. above.
To quantify the conductivity and fluorescence of these streams before
they enter Crooked Lake, the meter was transported by van to six stream loca-
tions shown in Figure II.D.24. Since the readings go off-scale of the meter
when channel adjustments are set for lake scans, the calibrated channel
adjustments themselves were used to determine strength of response.
The readings are presented in Table II-D-11. All of the organic signals
were too high to be brought back on scale without changing the f luorometer' s
polarizing filter. Inorganic channel readings were higher than lake settings
in Carpenter Ditch but lower in the Loon Lake stream. The flow in these
streams and their high fluorescence could probably explain all of the
fluorescence in Crooked Lake's hypolimnion.
Stream plumes can produce recordings that would deceive even experienced
surveyors. An example was recorded during a survey of Lake George, NY. The
recording is reproduced in Figure II.D.25. It was not until the tape for this
scan was examined days after the scan that the several peaks, which by
coincidence were recorded near houses, were recognized to be eddys moving
along the shoreline in the direction of the wind from the mouth of a small
plume. Examples such as this highlight the need for careful attention to
potential sources of fluorescent materials and a good understanding of
physical and biological limnology.
d. Feasibility of Detecting Effluents with Fluorometry Alone
The SLD detects two parameters: fluorescence and conductivity. In
theory, conductivity distinguishes between wastewater (which has more ionized,
dissolved solids, and, therefore, higher conductivity that the water supply)
and natural sources of fluorescence which do not release as much ionized
II-D-48
-------
Figure II.D.23 Shoreline Scan on South Shore Crooked Lake Where Stream from Loon
Lake Enters (Organic Channel Recordine1)
ecA
10-
K
1ft t
G
O
$
Ih
v<
-
pWt-
II-D-49
-------
;~"- ..C rT^^T *^r^!L__£NX% ^
p -jLi/;
s
ms ^--r i x
..- -^s^pi -py.i. ->. -^-^.--. I. •--[< -^ .-' ^
•^"/-^-'1-J- --:^MA ,^ -
'' x v" ^ i:! /^''
-, N\ '/ \y
-T r\ C^
-------
TABLE II-D-11. SLD READINGS FOR INFLOWING STREAMS
Stream and
No. Location Organic Zero Inorganic Zero
o
1 Stream from Loon Lake off-scale 506
just before entering
Crooked Lake
2 Stream from Loon Lake 718 501
at first road before
lake
3 Carpenter Ditch at off-scale3 805
road below Center Lake
ft
4 Carpenter Ditch mid- off-scale 802
way to Crooked Lake
a
5 Carpenter Ditch just off-scale 814
before entering
Crooked Lake
a
6 Ditch feeding canals off-scale 678
just east of Highway
200N
a Reducing span adjustment would not bring reading on-scale.
II-D-51
-------
Figure II.D.25 Stream Plume and Eddy Currents, Lake George, NY, August 1981
II-D-52
-------
material. The SLD's "combined" signal responds to rapid (although not
necessarily large-scale) changes in these parameters and automatically screens
out slowly changing background variations in either parameters. These
features provide the benefit of automatic data interpretation which allows the
operator to devote attention to other important survey information that will
later be essential to interpreting the recordings. The cost of this automatic
data interpretation is that potentially significant information on background
levels of fluorescence and conductivity are not recorded unless separate notes
based on visual meter readings are taken. Also, the benefit of automatic data
interpretation is somewhat diminished because the quantitative relationship
between rates of change in conductivity, fluorescence and the resulting
combined signal are not published.
Because of these concerns and the high cost of currently available SLD's
(the ENDECO 2100), interested investigated have asked whether a fluorometer
alone or perhaps a fluorometer operated simultaneously but separately with a
conductivity probe may provide as much information at a much lower cost.
To address this concern during the Crooked Lake field investigations, two
approaches were taken: 1) repeat scanning of shoreline segments recording
fluorescence only one time, then combined signal another and 2) operation of
the SLD in series with a laboratory model fluorometer (Turner Model 10)
equipped with the same type light source, filters, and photomultiplier tube.
Comparison of fluorescence and combined recordings on the same stretch of
shore was illustrated in Figure II.D.19. The same type of comparison is made
in Figure II.D.26 for another stretch.
In general, the combined recordings indicate effluent plumes in some
locations where the fluorescence recording along was interpreted as reflecting
small background or equipment-related fluctuations. The combined signal will,
therefore, indicate that more plumes are present than will fluorescence alone.
Whether any of the plumes "lost" by recording fluorescence alone are signi-
ficant in terms of bacteria or nutrients was not evaluated.
The SLD and the laboratory fluorometer were connected with tubing such
that water from the probe flowed through the laboratory fluorometer, then
through the the SLD. The laboratory fluorometer responded in tandem with the
SLD fluorometer as would be expected. However, the meter changes on the
laboratory fluorometer were much smaller than those of the SLD. Only the
streams and the strongest effluent plumes produced recognizable peaks by
inspection of the laboratory fluorometer's meter. It was subsequently
determined that changes could have been made to increase the sensitivity of
this instrument. However, a direct comparison was not accomplished in the
field because the necessary modifications were not made.
Assuming that a fluorometer can be modified to respond like the SLD's
fluorometer and a fast-response conductivity probe could be connected to a
two-channel recorder with the fluorometer, researchers could obtain much of
the data provided by the SLD. The main differences between such an equipment
combination and the available SLD is automatic data interpretation and detect-
ability of weak or dispersed plumes.
II-D-53
-------
Second Basirx; 14 September
Id- ^
-------
The automatic data interpretation function of the SLD is patented and the
design details are proprietory. Particularly when limited time is available
or when requested scans are not feasible, this feature can be very valuable.
However, a person with extensive experience with a fluorometer alone or a
fluorometer/conductivity meter/recorder combination may not be at a serious
disadvantage regarding time and scheduling.
Regarding the detectability of weak or dispersed plumes, insufficient
work has been done to discount their importance. However, detailed sampling
of a number of easily detectable plumes shown that only a fraction also have
nutrients or bacteria at levels to be of concern. Weaker plumes would be
expected to have even fewer pollution problems. Therefore, if the septic
leachate survey's purpose is to find and sample the worst effluent discharges,
the enhanced plume detection may not be necessary. On the other hand, if the
purpose is to find all possible wastewater sources or if surveys might be done
under suboptimal conditions of wind and waves, the apparent ability of the SID
to discern weak plumes would be valuable.
Acknowledgement: Spectrophotofluorometry and thin layer chromatography
were performed by Dr. Daniel W. Armstrong of Georgetown University,
Washington, DC. His advice and expertise are greatly appreciated.
II-D-55
-------
REFERENCES
American Society for Testing and Materials. 1976. List of Fluorescent
Whitening Agents for the Soap and Detergent Industry. DS 53 A. ASTM,
Philadelphia PA.
Armstrong, Daniel W., W. L. Hinze, K. H. Bui and H. N. Singh. 1981. Enhanced
Fluorescence and Room Temperature Liquid Phosphorescence Detection in
Pseudophase Liquid Chromatography (PLC). Analytical Letters, November,
1981.
Environmental Devices Corporation. i-ft8.0- ENDECO Type 2100 Septic Leachate
Detector System (Septic Snooper ) - Operation Manual. ENDECO, Marion
MA.
K-V Associates, Inc. 1979a. Investigations of Septic Leachate Discharges,
Ottertail Lake, Minnesota, April 1979. Published in: Draft Environ-
mental Impact Statement Appendices, Alternative Waste Treatment Systems
for Rural Lake Projects. Case Study Number 5: Otter Tail County Board
of Commissioners, Otter Tail County, Minnesota. U.S. Environmental
Protection Agency, Region V, Chicago, IL.
K-V Associates, Inc. 1977b. Septic Leachate and Groundwater Flow Survey,
Otter Tail Lake, Minnesota, September 1979. Published in: Final Envi-
ronmental Impact Statement, Alternative Waste Treatment Systems for Rural
Lake Projects. Case Study Number 5: Otter Tail County Board of
Commissioners, Otter Tail County, Minnesota. U.S. Environmental
Protection Agency, Region V, Chicago IL.
K-V Associates, Inc. 1979c. Investigation of Septic Leachate Discharges into
Steuben Lakes, Indiana, December, 1978. Published in: Draft Environ-
mental Impact Statement Appendices, Alternative Waste Treatment Systems
for Rural Lake Projects, Case Study Number 4: Steuben Lakes Regional
Waste District, Steuben County, Indiana. U.S. Environmental Protection
Agency, Region V, Chicago IL.
K-V Associates, Inc. 1977d. Septic Leachate and Groundwater Flow Survey,
Steuben Lakes, indiana, 1979. Published in Final Environmental Impact
Statement, Alternative Waste Treatment Systems for Rural Lake Projects,
Case Study Number 4: Steuben Lakes Regional Waste District, Steuben
County, Indiana. U.S. Environmental Protection Agency, Region V,
Chicago IL.
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APPENDIX II-D
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E. SEPTIC LEACHATE DETECTOR POLICY
Research and field studies with septic leachate detectors sponsored by
U.S. EPA, Region V to date have been based on an ENDECO Model 2100 Septic
Leachate Detector and its prototypes. The recommendations made here regarding
its use and its eligibility for use or purchase with federal grants are not
intended to apply to other devices for locating wastewater in natural water
bodies. Neither support for nor restrictions on other specific makes of
equipment should be inferred from these recommendations, since the authors
have not tested devices other than the one identified. In general, however,
Region V encourages development of any device or method that facilitates
location and remediation of insufficiently treated wastewaters.
1. INTERPRETATION OF DATA
As discussed in the preceding Technical Reference Document, the septic
leachate detector is subject to certain limitations that must be recognized
during use and in interpretation of the data it generates. The most signi-
ficant limitation is that it cannot quantify the strength of wastewater in a
sample or body of water. The organic and inorganic substances that it
monitors can be transported through soil and water quite independently of
other wastewater constituents. Even fluorescence and conductivity are
recorded in relative, not quantitative, units. In order to quantify the
concentrations of nutrients, bacteria, or other wastewater constituents, flow
through the meter can be sub-sampled, or samples can be collected by conven-
tional means for later analysis. The advantage of the detector is that it
permits collection of samples in demonstrated effluent plumes.
Aside from the limit on quantification, septic leachate detector surveys
are subject to false positives and false negatives. Most of these potential
errors are due to the dynamic nature of the natural systems involved, and to
variability in wastewater characteristics. False positives can be caused by:
• Naturally fluorescent decay products from dead vegetation. Swamps,
marshes, and peat deposits can leach tannins, lignins, and other com-
pounds that fluoresce in the detection range of the fluorometer. The
conductivity measurements provided by the detector are intended to
differentiate such signals, but in practice dilution may eliminate
detectable conductivity changes expected from wastewaters, thus making
a wastewater plume appear similar to natural decay products.
• Sediment or air drawn through the detector can cause dramatic changes
in the monitor readings. This is usually noted by the operator and
recorded on the recorder tape.
• Eddy currents carrying large wastewater or bog plumes can appear to be
individual plumes from on-site systems.
The more serious errors are false negatives, since these may indicate that
there is no problem when in fact a problem exists. Notable errors caused by
false negatives included:
o High dilution of wastewater in a lake or in groundwater, as mentioned
above, may reduce conductivity differences to the level of normal
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background variations. The absence of conductivity differences will
cause the detector to electronically mask fluorescence signals that are
detected.
• Mixing of lake water by wind and waves can disperse leachate very
rapidly, causing normally strong effluent plumes to be missed al-
together. The time it takes for leachate to accumulate along a shore-
line to detectable concentrations is dependent on several factors that
have not yet been studied.
• Fluctuations in lake level can slow or even reverse normal groundwater
flow, temporarily eliminating leachate emergence at a shoreline.
• Groundwater recharge by rainfall, snowmelt, or irrigation will also
affect the dynamics of leachate movement.
• Seasonal use of dwellings may result in only periodic emergence of
leachate at a shoreline.
Due to these factors, the data generated by septic leachate detectors has
to be carefully interpreted before it can be considered to be useful informa-
tion. Interpretation is aided by the following supplementary data collected
or recorded before, during, and after the shoreline scan as noted:
Before
• Surface and subsurface watersheds, as suggested by topographic maps and
available groundwater hydrology reports
• Groundwater flow, as determined by meters or other methods
• Soil types
• Wetlands and other sources of organic decay products in the watershed
• Locations of surface malfunctions identified by aerial photography
interpretation
• Design, usage, and performance of on-site systems identified by on-site
sanitary inspections
• Changes in lake elevation up to the time of the survey.
During
• Weather conditions, especially wind speed, wind direction, and recent
rainfall
• Lake stratification and surface currents
• Observed non-wastewater sources of fluorescence or conductivity, such
as culverts, drainage ditches, salt storage areas, landfills, abundant
organic material in near-shore sediments
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• Observed direct discharges
• Likely proximity of on-site systems near shoreline
• Operational mishaps such as stirred-up sediments, air drawn through
meter, and engine backwash
• Sensitivity and zero adjustments for fluorescence and conductivity
channels
• Frequent notation of visual meter readings
• location, time, and conditions of water sample collection.
After
• Water sample analysis results.
All of these types of supplementary data need not be collected for every
shoreline scan. The person responsible for a survey must have the ability to
select appropriate data collection methods so that the equipment responses can
be meaningfully interpreted.
2. ELIGIBILITY OF SURVEYS AND EQUIPMENT FOR CONSTRUCTION GRANTS
FUNDING
Because of the possibilities for error and the many factors influencing
the results of septic leachate detection, the validity of surveys rests
heavily on the experience, knowledge, and judgment of the surveyor. Until
additional evaluation is made of the factors influencing survey results,
septic leachate surveys will be eligible for Construction Grants funding only
when:
1) the person in charge is experienced in operation and maintenance of
the detector model being used. At least two weeks of field
experience is necessary for assisting someone who is already expert
with the model;
2) the person in charge is present during any shoreline scans that are
reported;
3) data is interpreted by a person who has a professional background in
liminology; and
4) approximate wind speed and direction are noted during the survey,
and reported.
Septic leachate detectors should prove to be valuable monitoring tools for
communities managing shoreline on-site systems. Purchase of detectors will be
eligible for Constructon Grants funding. Grantees will be required to show
that comparable instruments are not available on a timely basis from other
nearby grantees. Funded instruments will be made available to other grantees.
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F. AERIAL PHOTOGRAPHY METHODS AND POLICY
Properly acquired and interpreted aerial photography can provide data on
surface malfunctions of on-site systems. With this technique, a community
survey can be made rapidly and at relatively low cost without intruding on
private property. Aerial photography detection of surface malfunctions is a
three-step process involving acquisition of the photography, identification of
suspected malfunctions by an experienced photointerpreter, and field checking
of the suspected malfunctions.
Optimum coverage, resolution, and signature recognition can be achieved
using fine-grained color infrared film flown to a scale of approximately
1:8000 (1 inch = 1667 feet). Other image types can be acquired in conjunction
with the color infrared film, such as true color, thermal infrared, or thermal
scans. However, experienced photointerpreters (Evans, 1981) feel that color
infrared film will be adequate.
Timing of the flight is an important consideration in remote sensing of
surface malfunctions. These failures can best be detected when groundwater
elevations are highest and foliage is minimal. Therefore, best results for
permanent residences are obtained during spring or late winter when the ground
is not snow-covered. Tree cover present during the remainder of the year can
limit detection of surface malfunctions. In cases where aerial photographs
must be taken during summer months, such as in communities with seasonal
populations, the subsequent interpretation and field checking phases must be
conducted more cautiously. Also, flights can be completed with substantial
overlap of photos, thus affording stereoscopic analysis of on-lot features.
With sufficient overlap, interpreters can actually see under some of the
taller trees.
Suspected malfunctions should be identified from the photography by an
experienced photointerpreter. This experience is needed to distinguish valid
signatures from those of unrelated phenomena such as shade, natural vegetation
and wet soils, and artificial surface drainage features. Surface manifesta-
tions of surface malfunctions include:
• Conspicuously lush vegetation,
• Dead vegetation (especially grass),
• Standing wastewater or seepage, and
• Dark soil, indicating excessive accumulation of organic matter.
The suspected malfunctions should be field checked. The ideal person to
do this is the photointerpreter, although others may perform the task. By
inspection and, if feasible, by interview with the residents, the suspected
malfunctions are reclassified as:
• Confirmed malfunctions - standing wastewater from an on-site system is
visible on the land surface,
• Marginal malfunctions - accumulation of excess organic matter or the
presence of dead vegetation, indicating that wastewater had surfaced in
the past, or
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• Irrelevant signatures - visible surface or vegetative features which
mimic the visual characteristics of malfunctions but are not caused by
wastewater.
Aerial photography acquired for this purpose can be used for other pur-
poses during facilities planning, such as:
• House counts,
• Land use, vegetation and wetlands analysis, and
• Layout of wastewater collection and transmission facilities.
To accomplish the last purpose listed above, precision flights may be
necessary to overcome resolution problems that can result from the normal
tilting of the airplane during photo missions. No special preflight measures
(establishment of reference points, etc.) are required. Available maps can
serve as a guide on precision flight missions. Precise photo missions enhance
the three-dimensional effect already characteristic of aerial photographs,
thereby enabling facilities planners to complete detailed design of wastewater
collection and transmission facilities. These data supplement those contained
in USGS topographic maps. The cost of precision flights can be expected to be
approximately 50% greater than normal photographic missions. The decision to
make a precision flight should be based on the likelihood that large portions
of the facilities planning area will require centralized collection and
treatment. Otherwise the extra cost cannot be justified.
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G. SANITARY SURVEY METHODS AND POLICY
1. PURPOSES OF SANITARY SURVEYS
Sanitary surveys are among several data collection and analysis
methodologies that can be used in unsewered communities to assess the need for
improved wastewater facilities. If continued use of on-site systems is
planned, the sanitary survey is a fundamental step in selecting and designing
the improvements.
Design of a sanitary survey depends on the expected uses of the informa-
tion to be collected. For this report, it is assumed that the study is con-
cerned primarily with existing on-site wastewater systems, and secondarily
with nearby water supply wells and springs that may be affected by the waste-
water systems. Trash, rodents and other matters that could be included in a
community sanitary survey are not considered here.
Within this defined scope, sanitary surveys can achieve several specific
objectives:
1) Identify possible sources of water quality and public health
problems. This is a fundamental requirement for facilities planning
in unsewered communities. Other methods, such as aerial photography
interpretation, review of health department files, or interviews
with septic tank contractors, might meet this purpose or augment
sanitary surveys in doing so.
2) Evaluate causes of system malfunctions. Causes for some malfunc-
tions can be determined readily by interviewing the resident or
inspecting the site. The interviewer's experience and the home-
owner's knowledge of his or her system will affect the proportion of
malfunctions that can be explained during the first visit.
3) Assess the feasibility of continued use of on-site systems. Cost
studies have shown that where continued use is feasible, it is
nearly always cost-effective compared to installing sewers. The
performance of existing systems is the best indicator of this
feasibility.
4) Provide a quantitative information on the types and frequencies of
malfunctioning systems, as a basis for projecting renovation and
replacement needs and for estimating the costs of community-wide
optimum operation alternatives. Decisions made to sewer or not to
sewer an area depend on meeting this objective at least approxi-
mately, and even a partial survey can furnish sufficient data for
projections.
5) Collect information on individual properties and their on-site
systems, for later use in the process of designing renovation and
replacement facilities if continued use of these systems is the
selected alternative. The first step in the design process, which
is normally to collect such information, will thus already have been
completed for surveyed properties.
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Because the design of the survey will determine in large part how suc-
cessfully these objectives are met, the persons responsible for the survey
should initially assess the relative importance of each of these categories of
information in their local planning situation.
2. TERMINOLOGY
Before discussing the design of sanitary surveys, conventions on the use
of terminology will be stated.
In its common usage, the term "sanitary survey" can apply to any evalua-
tion of hygienic conditions on a specific property or within an entire com-
munity. However, "sanitary survey" as used here is defined more specifically,
and refers to resident interviews, visual site inspections, and (as appro-
priate) water supply inspections for all or a portion of the dwellings and
businesses in a community. A "complete sanitary survey" is one intended to
reach all occupied places; and a "partial sanitary survey" is intended either
to sample a representative portion of the community, or to survey places that
had been previously selected on the basis of past problems, poor site condi-
tions, or other factors. A sanitary survey includes preparation, on-site
sanitary inspections, and analysis of the information acquired. An interview,
site inspection, and water supply inspection for an individual property is
termed an "on-site sanitary inspection" to distinguish it from the broader
meaning of sanitary survey.
When sanitary surveys are performed in the context of facilities planning
for the EPA Construction Grants program, the terms "needs documentation" and
"detailed site analysis" establish a valuable distinction. "Needs documenta-
tion" refers to data collection for the purpose of community-wide or segment-
wide alternatives development and selection. "Detailed site analysis" refers
to the type of data collection that is required to analyze the condition and
performance of an individual system so that renovations or replacement facili-
ties can be designed. On-site sanitary inspections can be the pivotal data
collection effort in either needs documentation or detailed site analysis.
However, when it is clear from available data that continued use of on-site
systems will be the selected alternative, performing a sanitary survey during
facilities planning is optional. In such cases, the sanitary survey can be
deferred so that it becomes an integral part of the detailed site analysis.
In some cases, available data, together with the information collected in
a sanitary survey, may not be sufficient to describe the performance of on-
site systems. This may occur where the suspected problems or their causes are
not obvious either to the resident or to the surveyor. Sampling of soil
conditions, groundwater quality, or groundwater hydrology may be needed in
such cases to reveal the fact or the causes of poor system performance.
Limited sampling intended to explain typical problems is called "representa-
tive sampling," and normally is conducted concurrently with a sanitary survey.
3. PREPARATION FOR THE SURVEY
The design of a sanitary survey can vary considerably, depending on its
purposes (see Section 1 above), available funds, the expertise of available
personnel, and the extent of existing information on the performance of on-
site systems in a community.
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The first decision to be made will often be whether the survey should be
partial or complete. If decisions to sewer significant parts of a community
cannot be supported with available data or inexpensive data collection
methods, a partial sanitary survey reaching anywhere from 10% to 80% of
occupied buildings may provide sufficient information while costing less than
a complete survey. Data from a survey will have little future utility if the
survey (along with cost, feasibility and environmental analysis) indicates
that sewers are necessary. If conditions are that severe, a partial survey
should reveal that fact while avoiding unnecessary work and expense. On the
other hand, if it is reasonably clear that most or all of a community will
continue to use on-site systems, then a complete survey may be more efficient
in the long run. The quality of data on system performance available prior to
the survey will affect the decision on whether a survey should be partial or
complete. If comprehensive and up-to-date data are available, the outcome of
needs documentation (to sewer or continue using on-site systems) will be
predictable and the chances of over-surveying or under-surveying will be
reduced. The most common sources of available data are health department
permit records, soil maps, and interviews with local septic tank contractors,
well drillers, sanitarians, zoning officials and soil scientists.
If a partial sanitary survey is called for, good available data may also
enable the survey designer to emphasize analysis of the causes of failures.
If the available data already identifies most of the failures, then the survey
can be "targeted," that is, can concentrate on analyzing known problems and
making preliminary identification of the required replacements and renova-
tions. However, if the failure rate cannot be estimated from available data,
it might be better to design the survey to estimate this statistic and to
pinpoint the most frequent failures. A random survey, aimed at inspecting
some predetermined fraction of occupied buildings, can accomplish this aim and
provide an estimate of overall failure rate.
Two closely related factors in survey design are the personnel and the
funds available to do on-site sanitary inspections. If funds are very
limited, and the main purpose of the survey is to locate problems, then local
volunteers or low-cost, part-time employees might be trained in a day or two
to find the obvious failures. Such an approach would be useful, for instance,
where available data is poor but does suggest that failure rates are high and
that sewers will be necessary. More experienced surveyors or small system
experts can be sent in later if they are needed to analyze specific problems.
On the other hand, many planning situations will dictate that experienced
personnel be used from the start. If expected problems are not obvious (for
example, well contamination) or are difficult to analyze without disrupting
the property (as with some plumbing backups) , it may not help the facilities
planner to have to deal with conjectures from inexperienced surveyors. If the
survey designer expects that the project will end up implementing on-site
renovation and replacement, then having highly qualified individuals
responsible for the entire process from survey design through facilities
construction might be less expensive in the long run.
Another variable to be weighed is the length of time available to com-
plete the survey. For instance, a community that has made a long-term com-
mitment to manage on-site systems for its property owners may be in a hurry to
locate only the obvious problems at first, problems which can be located well
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enough by inexperienced surveyors. If the planning situation is complex,
however, or financial assistance depends on the timely completion of applica-
tion documents, then a team of experts might be needed to complete the survey
and deliver their results quickly so that other necessary decisions and
actions may proceed.
The validity of an on-site sanitary inspection rests in large part on the
willingness and ability of the person being surveyed to respond accurately and
completely to the surveyor's questions. An experienced surveyor can maximize
the information gained by knowing what questions to ask and being able to
respond to a variety of questions about the project that the resident might
ask.
However, any surveyor's efforts will be more productive if residents have
been prepared for the inspection by advance publicity that answers the fol-
lowing questions:
• What are the purposes of the survey?
• What are the types of information that will be sought?
• How will this information be used?
• How can residents cooperate in the survey?
Information that can accomplish this advance preparation may be disseminated
in a variety of ways. Local newspapers, radio, and television are effective
means of publicizing a survey. Notices sent to civic associations may also be
valuable. Another method of publicizing a survey, which can also be used to
gather information of value in planning the survey, is that of direct mailing
of questionnaires and fact sheets to residents. An example of a mailed
questionnaire previously used by EPA Region V will be found in Appendix A.
The cost of duplicating, mailing, and analyzing mailed questionnaires may be
justified by the enhanced ability to target inspections in areas with reported
problems. The response rate may also be taken as an index to public support
for a project.
Prior to the survey, suitable forms for guiding the on-site sanitary
inspections and for recording information should be developed and reproduced.
A useful form that EPA Region V has developed to standardize its own surveys
is included herein as Appendix B. This form incorporates the following
features:
• It is general enough for use with nearly any site.
• It is designed to be used by surveyors who have received training in
its use. Many of the entries must be made in blank spaces — the
surveyor must know what to ask and what to record.
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• The format follows the progress of a typical survey. The first page
records information from the interview, the second from the site
inspection, and the third from a well inspection, if one is made.
The extent of variation in recorded responses can be controlled by provi-
ding each surveyor with a separate list of possible entries, particularly for
such items as "Type of Sewage Disposal System" and "Surveyor's Visual
Observations of Effluent Disposal Site." Because terminology changes from
place to place, one of the steps in preparing for a sanitary survey may be
developing such a "crib sheet" based on interviews with local officials and
contractors.
Lastly, the logistics of getting together surveyors, forms, sampling
equipment and containers (if any), and suitable transportation for the
surveyors must be worked out. For quick-turn-around surveys, proper planning
of such small matters may be critical to the survey's success.
4. ON-SITE SANITARY INSPECTIONS
The basic elements of an on-site sanitary inspection are an interview
with the resident and an inspection of the property, focusing on the locations
of on-site wastewater facilities. To these may be added as appropriate: a
well or spring inspection, sampling and analysis of the water supply, sampling
and analysis of groundwater that directly receives wastewater effluent, soil
sampling and analysis, and follow-up inspection by more experienced personnel.
At the beginning of an interview, it is imperative that the surveyor
clearly state the purpose of the interview, the name of the sponsoring agency,
and the name of the project. An explanation of how the information will be
used should also be offered if the resident is not already informed.
Since many sanitary surveys will be conducted prior to the establishment
of mandatory access provisions, the resident's permission to conduct an
inspection will be required. A signed letter of introduction from the head of
the sponsoring agency may help obtain permission.
The surveyor should judge whether the resident is competent to provide
the needed information. Small children, visitors, short-term renters, baby-
sitters, etc., may be willing to allow access and to answer questions, but may
not be able to provide adequate responses. A given resident may not be the
person who is best informed about the property, but may nevertheless be able
to describe past problems with the on-site system, or provide data on
occupancy and water-using fixtures. Depending on the purposes and design of
the survey, a surveyor may decide to terminate the inspection, to use incom-
plete or unreliable data from anyone present in the residence, to return when
the best-informed resident will be available, or to search for landlords or
other informed persons. Some surveyors have used a system of response ratings
in order to quantify the willingness of residents to respond and their ability
to provide information. These ratings will be discussed in Section 5 below,
in relation to data interpretation.
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The recommended survey form reproduced in Appendix B shows data that can
be aquired during resident interviews. The data categories are explained on
pages immediately following the three-page form. Information acquired during
the interview should be entered on the form immediately, since to delay
recording this information can lead to unnecessary errors and often means
that the information is never recorded.
As mentioned earlier, the recording of information from the interview
will be aided by a "crib sheet" containing the most likely responses to
selected items. Wide variation exists in local terminologies referring to
plumbing fixtures, parts of on-site systems, and system failures. To facili-
tate discussions with residents, and to make survey entries as uniform as
possible, lists including both local and more widely accepted terms might be
prepared for each surveyor. Drawings of typical parts of on-site systems and
wells would also aid communication.
The next step is an inspection of the property, with the resident's
permission, and preferably, accompanied by the resident. Known or suspected
locations of all sanitary facilities should be observed. If the resident is
not able to identify facility locations, it will normally be appropriate for
the surveyor to estimate relevant information based on such factors as the
topography of the lot, the locations of wells, and previous knowledge of
systems serving houses of similar age. The degree of uncertainty in such
estimates should be noted by comments in the margin of the survey form.
The property inspection should not be limited to reported sanitary faci-
lities. Streams, drainage ditches, field tiles, lakes, and ponds on or
adjoining the property should be inspected for signs of illegal discharges,
nutrient enrichment, and possible impact on drinking water supply. Property
boundaries should be walked in search of unreported wastewater discharges.
Surface drainage that may interfere with proper soil absorption should also be
noted. Any nearby water supplies that may be affected by existing systems or
by possible replacement facilities should be located.
Page 2 of the form in Appendix B provides space for recording visual
observations in narrative form and in a sketch. A check-list of drainage
characteristics is also provided. Surveyors should be provided with ruler,
compass and pencils to sketch the property, buildings, water bodies, and
sanitary facilities.
Many buildings served by on-site wastewater systems also receive their
fresh water from on-site wells or springs. Decisions to continue using on-
site wastewater systems must consider the impact these systems are having on
such water supply sources. These sources will be located during the property
inspections, and should be examined to check for the integrity of casings,
adequacy of surface drainage, proper venting, and the presence of grouting (in
some geologic settings). During initial surveys, wells that may also be
subject to contamination from sources other than on-site wastewater systems
should not be sampled, since positive analysis for coliform bacteria or
nitrates might be due to inflow from surface runoff or other non-wastewater
sources, and decisions to modify or abandon wastewater systems based on well
sampling results would then be in error. Results of all well inspections and
other data that the resident may have on well depth and depth to water may be
recorded on the third page of the survey form in Appendix B.
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During intensive surveys, a number of surveyors may be working at the
same time. Some or most of them may be inexperienced. Two devices have been
used to maintain the quality of information developed from such surveys. One
is a daily feedback meeting in which surveyors are brought together to sum-
marize and discuss difficulties in conducting inspections, and to report
notable results. These meetings provide additional training for surveyors,
and reinforce their use of uniform terminology, while providing survey leaders
with an opportunity to gain input on survey progress and results. Such
meetings also provide opportunities for adjustments of survey design while the
surveyors are still in the field.
The other device is a follow-up inspection by more experienced personnel.
If most of the survey staff are inexperienced, they may be able to find mal-
functions, but be unable to assess the causes of the malfunctions or to
prescribe supplemental investigations. Such reinspections by experienced
surveyors may yield optimum survey results for the funds spent.
5. INTERPRETATION
Each property that is surveyed is unique, and may vary widely from other
properties in terms of site conditions, system design and usage, and resident
responsiveness. It may seem to a surveyor that to distill the many bits of
data from such a survey into useful planning information is not possible with
just a partial sanitary survey and some representative sampling. It could
even be argued that precise descriptions of necessary on-site remedies could
be made only after replacement facilities and renovations are constructed—and
even then we would not know whether the best designs had been selected until
the systems had been in operation for several years! How, then, should a
facilities planner proceed?
This question can be answered on two levels. The first level is that of
the individual system. If continued use of on-site systems is proposed, it is
at this level that a community's wastewater problems will be solved—one
system at a time. The on-site sanitary inspection forms record the first step
in the process of designing and constructing appropriate remedies for indi-
vidual on-site systems. Subsequent steps will also be taken for individual
systems, one system at a time. Following these steps for all the systems that
need them will result in economies of scale, as well as comprehensive and
effective abatement of problems.
The second level is that of the community. It is possible that a deci-
sion may be made to inspect and upgrade individual systems in a community-wide
program without specific or conclusive knowledge as to what will be done on
each property. At this community-wide level, the task is not to select
specific remedies for individual properties, but to assess for the community
as a whole (or significant parts of it) the following:
• The feasibility of abating most or all of the community's water quality
and public health problems with on-site remedies;
• The comparative long-term costs of doing nothing, of constructing
on-site remedies, of constructing centralized sewers, or of some
combination of these options; and
• The environmental and social impacts of the major options.
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If facilities planning before and after a sanitary survey is conducted with
these assessments in mind, and the survey is designed to provide appropriate
(even though approximate and partial) information, then good facilities
planners can make the essential, community-wide decisions using survey data.
Of course, in arriving at these community-wide decisions, some determinations
must be made as to whether selected individual systems should be abandoned,
replaced, renovated, repaired, or left along. But it is not essential that
these assessments be conclusive for individual systems, or that all individual
systems be surveyed.
In the interpretation of individual on-site sanitary inspections, two
types of possible responses from residents should be considered: those based
on poor knowledge of their systems, and deceptive responses. Many residents,
even heads of households and property owners, can provide only vague informa-
tion on the design and maintenance of their systems. This, of course, is a
significant factor in the failure of many systems. But it also limits the
amount of information that a surveyor will have to assess the system, it may
increase costs by requiring further work to complete the assessment, and it
increases the burden on the surveyor to understand and interpret other clues
to system design and performance. As time and expense allows, and the purpose
of the survey demands, the absence of knowledgeable persons can be overcome by
return visits, written or telephone inquiries, review of official permit
records, or requests for information from contractors who may have installed
or serviced the wastewater system. If no resident or owner has the necessary
information, only the latter two methods would be fruitful.
A more insidious problem is that of deceptive responses. Individuals may
not disclose the requested information if they do not understand the purpose
of an on-site inspection, or if they are concerned about costs that may be
incurred as a result of what is learned. However, some information, such as
problems with plumbing backups, can be obtained from no other source. On the
other hand, residents who support abandonment of on-site systems may exag-
gerate the frequency or impact of problems.
In some cases, deception may go undetected by the surveyor. However,
there will often be some evidence or clue that such deception is occurring.
These clues can include unwillingness on the part of a resident to allow
inspection of the property, signs of surface malfunction where none was
claimed, or behavioral clues that indicate a resident's attitude. Again, the
surveyor's response to perceived deception depends on the purpose of the
survey. If the purpose is just to locate problems by a partial survey, the
inspection may be completed but not included in a statistical description of
the problems in a community. However, if the survey is part of an ongoing
program to upgrade systems, follow-up inspections by senior project members or
by local officials may be necessary. The training and judgment of surveyors
are critical factors in proper handling of possibly deceptive responses.
Whatever the reason, the quality of information provided by residents
will vary. To account for this variable, some surveyors use a rating system,
of which the following is an example. This system was tested during a
targeted, partial sanitary survey at Lake George, New York. After each
interview, the surveyor placed a number from 0 to 5 on the first sheet of the
survey form. These numbers corresponded to the following assessments of
residents' responses:
II-G-8
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5- Resident has design drawings for system construction or repairs or
witnessed construction; has lived in dwelling long enough to know of
any problems; can communicate knowledge of system accurately.
4- Resident has hearsay knowledge of system design; has lived in
dwelling long enough to know of any problems; can communicate
knowledge so as to be understood.
3- Resident has lived in dwelling long enough to know of surface mal-
functions or backups, and has general understanding of system com-
ponents and their location. Not familiar with technologies used or
appropriate terminology. Explanations from surveyor required to
complete interview.
2- Resident can report on gross problems with system but can provide
little information on age, location, or design. Possible communi-
cation problems.
1- Resident can provide no information on system design and little, if
any, relevant information on surface malfunctions or backups.
0- Resident uncooperative. Information suspect or not provided.
Such a qualitative rating system for resident responses can assist survey
leaders in directing efforts to other sources of information or in extrapolat-
ing the inspection data to unsurveyed sites (see below).
Conclusions can be drawn from on-site sanitary inspections on the two
levels discussed previously, i.e., for individual systems and for the com-
munity. Many inspections will reveal no potential or ongoing problems. Of
the remainder, the appropriate course of action to remedy or forestall
problems will be readily apparent for some properties without additional
inspections or testing. Some fraction, however, will require one or more
special measures before an appropriate course of action can be selected and
designed. Interpretation of an on-site sanitary inspection at the individual
system level, then, includes categorizing the system according to whether
there is no problem, a problem with obvious solutions, or a problem which
requires additional work before a solution can be selected or designed. For
this latter category, interpretation should include prescribing the appro-
priate tests and inspections (See Technical Reference Document II.J. - Site
Analysis and Technology Selection for On-Site Systems). To this end, the
recommended survey form in Appendix B has resident approval blanks at the
bottom the of the first (interview) page.
Informed judgement is required to reliably interpret survey results in
terms of 1) assessing the causes of surveyed failures, 2) prescribing, to
various degrees of certainty, what the appropriate solutions will be, and 3)
extrapolating these data and judgments from surveyed properties to unsurveyed
properties. The degree of certainty to which these conclusions can be made
will depend on the same factors that were considered in designing the survey,
i.e., the purposes of the survey, the expertise and time available to perform
the survey, and prior knowledge of systems' performance. The strength of con-
clusions drawn from the survey will also depend on whether the causes for
system failures can be adequately analyzed from the information gathered.
II-G-9
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APPENDIX A
WASTEWATER TREATMENT QUESTIONNAIRE
Please indicate your answer by checking "V" the appropriate response where
applicable.
1. What kind of wastewater treatment system does your home primarily use?
Septic tank
Cess pool
Direct discharges } „. . . ,, -
^ . , , \ i ~* Skip to Question 3
Privy (outhouse) }
Holding tank
Other (describe)
2. Where does your system discharge?
Seepage field only
Seepage field plus surface discharge
Surface discharge through tile line
Other (describe)
3. Does your system discharge to a ditch or tile line?
Yes
No . •* Skip to Question 5
4. Where does this ditch or tile line eventually flow? (specify end point)
5. What is the age of your present system?
years (or) months
6. Approximately how many times has your treatment system had solids removed
from it in the last five years?
times
7. What is the depth of your wall?
feet
8. Is your well proceeded from run-off by being covered?
yes
no
9. What water sources, other than for the bathroom(s), are connected to
your treatment system? (^ all that apply.)
Cha. II-G A-l
-------
Question 9 continued
laundry
garbage disposal (grinder)
dishwasher
other (describe)
12a. Are there any liquid wastes which discharges some place other than your
primary treatment or sewage system?
yes
no -> Skip to Question 13
12b. Which wastes are these (sump pump, footing drain, roof drain, etc.)
12c. Where do these wastes go?
13. When do you usually perform maintenance tasks on your treatment system?
on a regular basis (for example, every summer.)
after a problem develops
never
other (describe)
14. What serious problems have you experienced with your treatment system?
I4a. Backup of wastes in the house
Caused by: Unusually heavy water use
____ Plugged pipe to septic tank
Full septic tank
Other (describe)
Solved by: Reduce water use
Clear obstruction from pipes
Pump septic tank
Rebuild system
Other (describe)
I4b. Odorous water surfacing at tile field
Caused by: Unusually wet weather
Unusually heavy water use
Full septic tank
Plugged tile lines
Other (describe)
A-2
-------
Solved by: Drier weather
Reduce water use
Pump septic tank
Install new tile lines
Other (describe)
I4c. Other problems (describe)
Caused by:
Solved by:
15. Are you aware that the Environmental Protection Agency would fund (if
the money is available) 85% of the cost of upgrading septic tank
systems if the Sanitary District would assume responsibility for them?
yes
no
16. Is your home a permanent or seasonal residence?
Permanent -» Skip to Question 18
Seasonal
17. Approximately how many weeks out of the year is your house inhabited
by you, your family or friends?
weeks
18. Approximately how long have you owned this home?
years (or) months
The following information is needed so that sewage treatment needs in
different areas can be identified. Again, all answers are confidential.
19. Which subdivision is your house located in?
(name)
20. What is the address of your property?
A-3
-------
Question 20 continued
Below, please make a sketch of your lot showing the following items:
the lake
the roads
your house
the well
the wastewater treatment system
the appropriate distance in feet between the treatment system and the
lake
the appropriate distance in feet between the wastewater treatment system
and the well
W
Thank you very much for your help on this study.
A-4
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APPENDIX B
SUGGESTIONS FOR USE OF
"SANITARY SURVEY OF CONSTRUCTION GRANTS APPLICATION'
This three-page form is intended to be used during initial sanitary
inspections of on-site wastewater systems. The intent of this form is to
guide surveyors in interviewing residents arid inspecting their properties so
that results are recorded as uniformly as possible, and include factors that
explain system performance as well as document satisfactory or unsatisfactory
performance.
This form assumes a certain level of knowledge on the part of surveyors
about on-site systems and the terminology used in describing them. Therefore,
instead of lengthy checklists for some entries, blanks are left to be com-
pleted at the surveyor's discretion. This form should not be used as a mailed
questionnaire, and should not be used by untrained surveyors. However,
experienced has demonstrated that a one-day training program can adequately
prepare people as surveyors. Such a program would include three to four hours
of instruction and two or three on-site sanitary inspections in the company of
a trained surveyor.
Recommended conventions in completing the entries are discussed below in
the order they appear on the form.
Resident - Enter the name of the person interviewed. If later cor-
respondence might be sent to a head-of-household who has not been not
interviewed and is not the owner, also enter his or her name in parenthesis.
Establish local conventions for completing this entry for non-residential
properites.
Owner - If different from the person interviewed, enter name. Also enter
address of owner if he or she does not reside here.
Address of Property - Self-explanatory.
Lot Location - Provide sufficient detail to enable others to find the
property.
Tax Map Designation - Enter tax map identification code, file number or
locally developed code to enable property to be located on available maps such
as soils maps, topographic maps, and tax maps.
Study Area - Enter name of community being surveyed, facilities planning
area, or locally developed identifier for the sanitary survey.
Surveyor/Date - Self-explanatory.
Weather - Note recent wet or dry periods or other climatic factors that
might influence on-site system performance at the time of inspection.
Approximate Lot Dimensions - Field estimates arrived at visually or by
pacing may be sufficient for preliminary surveys. Measurements from tax maps,
B-l
-------
tape measurements, or land surveys may also be called for in more intensive
surveys. Enter road or water frontage first. Local convention may call for
entering acreage here instead of dimensions.
Age of Dwelling - For preliminary surveys, the resident's estimate will
normally be sufficient. For determination of eligibility for federally funded
collector sewers, it is necessary to know whether the dwelling was built prior
to October 1972. For federally funded individual sewage disposal systems or
cluster systems, it is necessary to know if the dwelling was built before
December 1977.
Age of Sewage Disposal System - If available, this information should
come from the construction permit for the system. Resident's estimate may be
the only available information.
Type of Sewage Disposal System - Information on the existing system
provided by the resident may have to be supplemented by construction permit
records. Of specific concern are:
• Use of holding tank. If used, cite size, frequency of removal and
arrangements for removal.
• Size and construction of the septic tank, including material of
construction, whether open-bottomed or water-tight, and type of
sanitary tees and baffling.
• Size, construction, and type of aeration tank if used instead of septic
tank.
• Means of effluent transport to the disposal site, whether by gravity or
pump. If pumped, note presence of alarm device, provision of back-up
pumps, parallel pressure lines, type of pump pit, and reason for
pumping, whether to overcome topography or for dosing disposal site.
• Type of effluent disposal. Examples are cesspools, dry wells, shallow
drainage beds, lateral trenches with equal distribution, lateral
trenches with serial distribution, sand mounds, evapotranspiration
beds, and sand filters with surface discharge. Record dimensions of
cesspools and dry wells. Record number of trenches or beds and square
footage of trench or bed bottom, if available.
• Presence of multiple disposal systems such as dry well for laundry
waters, composting, recycling or incinerator systems for toilet wastes
or separate grey water and toilet wastes systems.
Maintenance - These entries are useful not only for the expected value of
the information, but also as an index to the user's knowledge of maintenance
requirements. Therefore, note in the right hand margin your assessment of the
interviewee's being "responsible" for the system's maintenace (owner or head
of household) or "not responsible" (children, visitors, etc.). Record inter-
viewee's responses, including "don't know."
B-2
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Dwelling Use: Permanent Residents - Record the number of adults and
children normally living in dwelling. Note whether any changes in occupancy
have occurred in the recent past, i.e., up to one year.
Dwelling Use: Number of Bedrooms - The number of potential bedrooms in a
dwelling generally limits its maximum occupancy rate, and so should be noted
for planning purposes. Questions arise as to the classification of some
spaces. A bedroom is defined for survey purposes as a room which can be
closed off from the rest of the dwelling and is not equipped specifically for
other purposes. The number of rooms normally in use as bedrooms are to be
counted as "actual" bedrooms on the survey form. Unfurnished basements or
other space which could easily be converted should be discussed with the
resident to determine whether there exists a possibility for future
"potential" bedrooms and their number. Bedrooms the resident is considering
adding by constructing new floor space should be entered as "planned."
Dwelling Use: Seasonal Use - Many variations in the level of occupancy
are found, especially in areas with recreational potential. Increased use by
weekend visitors, summer use by weekly renters, second home use on weekends
and full-time during the summer, and temporary use by migrant workers are
examples of the many types of variation in usage. Note the pattern of such
uses and approximate occupancy. Assume two people per bedroom if no better
information is available.
Water-Using Fixtures - Residences in rural areas often are not provided
with community water supplies. Water use data for use in predicting waste-
water flows will, therefore, not be available for many rural residences.
Knowledge of the dwelling use and of water-using fixtures can provide a basis
for estimating wastewater flows. Indicate the number of each type of fixture
in the spaces provided. Note which of the fixtures are designed to conserve
water. Also, if the residence is served by more than one sewage disposal
system (dry well, separate drain field, etc.), identify which fixtures dis-
charge to the smaller system by circling the names of the fixtures.
Problems Recognized by Resident - Problems with the existing sewage
disposal system will depend on the type of system. For typical septic tank-
subsurface drain field systems, problems recognized by the resident may be
limited to plumbing backups and leakage into basements. Odors and ponding
over the absorption field may be as apparent, but may occur only periodically.
Malfunction of aeration devices, clogging of sand filters, discharges from
broken hoses or effluent sewers, and seepage at the edges of mounds are other
examples of inadequate operation. The seasonality of such problems should be
noted. If wells are known or suspected to have been contaminated by on-site
or neighboring sewage disposal systems, note this with the resident's explana-
tion of the route of contamination, i.e., through groundwater or surface
flows.
At this point in the interview, the resident may describe other sewage
disposal problems in the neighborhood. This could be useful information, but
the interviewee may not want this information recorded. This could become an
ethical or legal problem. The leader of the sanitary survey should set a
consistent policy on this issue prior to the interviews.
B-3
-------
Resident Will Allow Follow-up Engineering Studies - As part of the
sanitary survey, detailed site analysis may be required on selected lots to
evaluate operation of the effluent disposal area and to determine the local
groundwater impacts of effluent disposal. These studies may include probing
the disposal area, augering soil samples, or installation of shallow ground-
water observation shafts. As these studies could be disruptive of the pro-
perty and the resident's privacy, written permission to conduct the studies
would be necessary. Determining the resident's cooperativeness and noting it
here on the survey form does not constitute that permission. However, knowl-
edge of the resident's cooperativeness will facilitate implementation of
follow-up engineering studies, and so should be noted.
Page Two - Water Supply
The interview should continue at least through the first two entries
concerning water supply source and cost and usage data. Remaining entries on
this page and the third page shold be completed during inspection of the site
and its water supply, wastewater and drainage facilities.
Surveyors may require training on local well construction techniques.
Page Three - Site Inspection
The information recorded on page one is derived primarily from an inter-
view with the resident as supplemented by data from tax assessor's records and
health department records. In contrast, information to be recorded on page
three will be based on the surveyor's inspection as supplemented by resident's
input and possibly health department records.
Optimally, the resident will allow a visual inspection of the property
and will be able to identify the location of parts of the sewage disposal
system, surface drainage facilities and the water supply. In this case the
information for Page Two should be readily obtainable.
In some cases, the resident may not allow the surveyor to walk the pre-
mises. The surveyor will be limited to recording observations made from the
property boundary. If the survey is limited in this manner, this fact should
be noted.
If the resident is not able to identify facility locations, and if health
department records do not fill such information gaps, it will normally be
appropriate for the surveyor to estimate relevant information based upon lot
topography, well location, etc. However, where the surveyor has to make
educated guesses about the type, size or location of facilities, the degree of
uncertainty should be noted by comments in the margin.
Surveyor's Visual Observations of Effluent Disposal Site - This space is
to be used for a narrative description of problems indicated by any part of
the sewage facilities or the property. The lack as well as the presence of
visible or olfactory evidence of malfunction should be noted. The surveyor
should attempt to determine whether past malfunctions have been disguised by
directing excess flows to drainage ditches, storm sewers or neighboring
B-4
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properties. Any site conditions which may limit the effectiveness of soil
absorption units, such as steep slopes, proximity to surface waters, etc.,
should be noted.
Drainage Facilities and Discharge Location - Soil-dependent effluent
disposal systems can be hydraulically overloaded by improper diversion of
groundwaters or surface waters. Careless diversion can also cause well
contamination. Careful inspection of drainage facilities may lead to
effective, easily implemented measures to remedy malfunctions and prolong the
useful life of the system. The resident may have to provide information on
the presence and discharge location of basement sumps and footing drains.
Discharge from roof drains and driveway runoff can normally be located
visually. Note the presence and discharge locations of these types of
drainage narratively in the space provided. Draw the discharge locations on
the Property and Facilities Sketch below.
Property arid Facility Sketch - In the space provided draw the following
i terns :
• Arrow pointing north
• Location and name of road access
• Lot boundaries, indicating approximate lengths
• Dwelling location and orientation
• Well location, indicating approximate distances to nearest lot
boundary, dwelling, septic tank or other storage/treatment unit, and
soil disposal area.
• Septic tank or other storage/treatment unit location and capacity, if
known.
• Soil disposal area or other disposal site location and dimensions,
depth, and design features if known.
• Drainage discharge locations.
• Surface drainage features such as storm sewer grates, ditches, streams
or lakes. Show direction and approximate distance to surface drainage
features if not adjacent to lot.
J-5
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APPENDIX B
ON-SITE SANITARY INSPECTION FORM
-------
SANITARY SURVEY FOR CONSTRUCTION GRANTS APPLICATION
Resident:
Owner:
Address of
Property:
Study Area:
Surveyor/Date:
Weather:
Lot Location:
Tax Map Designation:
Preliminary Resident Interview
Age of Dwelling: years Age of sewage disposal system:
Type of Sewage Disposal System:
Approximate Lot Dimensions:
feet by feet
rears
Maintenance:
years since septic tank pumped. Reason for pumping:_
years since sewage system repairs (Describe below)
Accessibility of septic tank manholes (Describe below)
Dwelling Use: Number of Bedrooms: actual, potential,
Permanent Residents: adults, children
Seasonal Residents: , length of stay
Typical Number of Guests: , length of stay_
Planned
If seasonal only, plan to become permanent residents:_
In how many years?
Water Using Fixtures (Note "w.c." if designed to conserve water):
Shower Heads
Bathtubs
Bathroom Lavoratories
Toilets
Plans for Changes:
Problems Recognized by Resident:
_Kitchen Lavoratories
_Garbage Grinder
Dishwasher
"Other Kitchen
jClothes Washing Machine
Water Softener
"Utility Sink
Other Utilities
Resident Will Allow Follow-Up Engineering Studies:
_Soil Borings
Well Water Sample
Groundwater
B-6
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SANITARY SURVEY FOR CONSTRUCTION GRANTS APPLICATION
Water Supply
Water Supply Source (check one)
Public Water Supply
Community or Shared Well
On-Lot Well
Other (Describe)
If public water supply or
community well:
If shared or on-lot well:
Fixed Billing Rate $ /
Metered Rate $ /
Average usage for prior year:
Drilled Well
Bored Well
Dug Well
Driven Well
Well Depth (if known):
Well Distance:
feet total
feet to house
feet to soil disposal area
Visual Inspection: Type of Casing
Integrity of Casing
Grouting Apparent?
Vent Type and Condition
Seal Type and Condition
Water Sample Collected:
No
Yes
(Attach Analysis Report)
feet to water table
feet to septic tank
feet to surface water
B-7
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SANITARY SURVEY FOR CONSTRUCTION GRANTS APPLICATION
Surveyor's Visual Observations of Effluent Disposal Site:
Drainage Facilities and Discharge Location:
Basement Sump
Footing Drains
Roof Drains
Driveway Runoff
Other
Property and Facility Sketch
B-8
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TM
H. EVALUATION OF THE DOWSER GROUNDWATER FLOW METER
1. INTRODUCTION
In conjunction with septic leachate detection surveys in several of the
Seven Rural Lake communities, a new groundwater flow meter was operated for
the first time on a full-scale basis. While considered at the^ime to be an
experimental, not a proven, device, the K-V Associates' Dowser groundwater
flow meter provided information on the rate and direction of groundwater move-
ment not otherwise available. The data generated, although subject to some
concern over quantitative accuracy, insights to local groundwater hydrology.
These insights helped explain other field study results and, in part, guide
the description and impact evaluation of the EIS's recommended actions.
TM
This report discusses the Dowser particularly in respect to traditional
groundwater flow estimation methods.
The somewhat academic explanation of groundwater data gathering
and analysis techniques that follows is to help the non-geohydrologist under-
stand the assumptions and thus the limitations of the techniques. After the
existing techniques are presented, the technical basis and applications
of the Dowser groundwater flow meter is discussed. The Dowser flow meter
is a tool useful for expanding and simplifying capabilities of geohydrologic
monitoring and modeling, but not for replacing those existing techniques.
2. THE EXPERIMENTAL BASIS OF GEOHYDROLOGY - DARCY'S LAW
The most common geohydrologic models employed in site investigations are
those predictive models of groundwater flow directions, rates, aad discharge.
These models may consist of physical, analog, or digital methodologies, but
all are basically derived from the empirical relationships discovered by Henry
Darcy in 1856.
Darcy is credited with being the first to recognize a relationship
between the velocity of flow through a porous medium (earth materials) and the
forcing function (hydraulic head differences). Using a column packed with
different combinations of soils and hydraulic head differences, Darcy recog-
nized the following experimental relationship.
Vat (1)
where V = groundwater flow velocity
and i = hydraulic head gradient
or V = Kl, (2)
where K is the constant of proportionality and includes the properties of the
fluid and the saturated, fluid-bearing zone. In geohydrology, the properties
(especially kinematic viscosity) of the fluid (usually water) are assumed to
be constant throughout the range of values normally encountered. The value K
is thus usually referred to as the Coefficient of Permeability and written as
k. The Coefficient of Permeability is a property of the earth material.
Thus defined, groundwater flow velocities may be calculated from the
relationship
V = ki (3)
II-H-1
-------
or the value of k may be determined in the laboratory by
W
Groundwater discharge (Q) is determined by multiplying the cross
sectional area (A) by the flow velocity:
Q = VA (5)
or
Q = (ki)'A (6)
3. EXISTING GROUNDWATER FLOW MODELS
Applying this relationship to field investigations , groundwater gradient
is established by measuring static groundwater elevations at three or more
non-colinear locations (usually by measuring water levels in three wells). A
site map of equipotentials is constructed. The maximum gradient found on this
map is assumed to represent the groundwater flow gradient. Groundwater flow
is assumed to occur parallel to streamlines at right angles to the equipoten-
tials (Figure II-H-1).
The coefficient of permeability of the aquifer (water-bearing zone) is
determined either by measuring samples of the material in the laboratory or by
choosing a value from the existing literature (Table II-H-1). The discharge
area is usually defined to include the saturated thickness of the aquifer
between the extreme streamlines which bound the site.
Limitations of this simplified method stem from the distribution of the
wells and from the determination of aquifer coefficient of permeability.
Observation wells must be constructed with a distribution suitable to detect
variations and singular points within the site. Some singular points which
may exist on a site and might affect the geohydrology include pumping wells,
pods or lenses of low permeability material, deep foundation, absence of lower
confining zones or sites of surface or subsurface recharge. Determination of
the coefficient of permeability from tables or discrete samples may introduce
errors by neglecting the variability of the material, secondary permeability
caused by bedding planes, joints or other structural features.
4. ALTERNATIVE DETERMINATION OF AQUIFER PROPERTIES - PUMP
TESTING
An alternative and more accurate method of determining the hydraulic pro-
perties of a water bearing zone is through the use of a pump test.
In one type of pump test, a production well and at least one fully pene-
trating observation well are required. The production well is pumped at
selected rate(s) and drawdown of the water table at the observation well(s) is
recorded. After completion of this test, recovery of head in the pumping and
observation wells is recorded. The result of this analysis is the determina-
tion of the transmissibility of the water-bearing zones. Transmissibility is
a value derived from the test result through the use of other empirical rela-
tionships. It is defined as the rate of flow through a vertical section of an
aquifer whose height is the thickness of the aquifer and whose width is one
foot, when the hydraulic gradient is 1.00.
II-H-2
-------
EQUIPOTENTIALS
STREAMLINES
(FLOW DIRECTION)
Figure II-H-1.
Diagrammatic representation of basic
site geohydrologic investigation for
a water table (unconfined aquifer).
II-H-3
-------
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The calculation of transmissibility, like other test data, is based upon
certain assumptions and generalizations. For accurate results, field condi-
tions must satisfy the assumptions upon which the formulae are based. A pump-
ing test may be a very useful method of determining the hydraulic properties
of water-bearing zones. It may yield reliable results which, in general, are
representative of average conditions within the zone of influence of the pump-
ing well. It does not give the details of groundwater flow at any point in
that zone.
5. THE DOWSER™ GROUNDWATER FLOW METER
TM
The Dowser groundwater flow meter is one of the first of an expected
new breed of groundwater monitoring devices. Recent increased interest in
groundwater supply and quality makes it seem likely that this market area will
soon experience an explosion in the number of similar devices in the near
future.
rpl^l
The Dowser represents an attempt to measure groundwater flow directions
and velocities without utilizing the Darcy law computations. A central
thermister generates a pulse of heat which is transmitted to the groundwater.
This heat pulse is transmitted through the groundwater more rapidly than the
actual groundwater flow rate. Net movement of groundwater past the probe
creates a bias in thermal conductance which is linearly proportional to the
groundwater flow velocity.
The main advantages of utilizing this type of device include the rapidity
with which measurements may be made, the availability in the field of ground-
water flow direction data, the availability of additional information on
groundwater flow at discrete locations on a site, and independence from
reliance upon the assumptions in Darcy low calculations for flow velocity.
Measurements of typically slow (on the order of tenths to tens of feet per
day) groundwater flow velocities may be made rapidly because the device mea-
sures bias in the thermal conductance of groundwater rather than groundwater
flow itself. Since the velocity of the heat pulse is much more rapid than the
groundwater flow rate, single measurements may be made in a short time (less
than 15 minutes). The thermal "tracer" used in the measurement is non-
polluting and not likely to be masked by the presence of other properties of
the earth materials or groundwater. The heat pulse tracer is also not likely
to be a contaminant of the site. This contrasts with the use of dyes or ions
which are otherwise used in groundwater tracer studies. These other tracers
may be absorbed and desorbed from earth materials in a chromatographic sense
which masks the true groundwater flow rate.
The availability of groundwater flow direction data in the field enables
the hydrogeologist to modify the field investigation as it proceeds, reducing
the need to remobilize drilling equipment or to leave gaps in the data uncol-
lected. Determination of a groundwater flow vector at a single well location
within a site provides more detail than would a typical site survey as pre-
sently conducted. The present site surveys describe average conditions over
the entire site, while a Dowser survey would supplement and provide con-
firmation of the general site conditions at discrete points. Finally, the
device measures a flow phenomena which may be calibrated directly to the
groundwater flow rate. It eliminates the need for the assumptions used in
Darcy flow calculations.
II-H-5
-------
TM
The Dowser device requires little technical training for operation, but
the interpretation of its results requires an experienced hydrogeologist who
is familiar with its use and limitations. First, the device can measure
accurately under laminar flow conditions only. This is not a problem for
groundwater flow under most conditions although it may be a problem for very
rapid flow through uniform coarse gravel where turbulent flow is possible.
Under turbulent flow conditions, mixing of the heat pulse in the eddying
groundwater would render measurements useless.
A second limitation for its use is in heat conductive earth materials,
especially in clay size and gravel size ranges. In the clay fraction, ground-
water flow velocities are typically very slow while the slaty texture and
mineralogy may induce heat transfer through the clay particles sufficiently to
mask the transfer in groundwater. In gravel, the probe thermistors may be in
direct contact with a single sediment grain. The heat transfer through this
single grain may mask the heat transfer in the groundwater. Groundwater flow
paths, measured by this device in gravels, may also err in that the actual
water flow paths may miss various detection thermistors as a result of their
travel around the individual grains.
The physical size of the probe may introduce limitations on the statisti-
cal validity of a measurement. In well layered clays, groundwater flow may be
concentrated in silt laminae which are continuous but very thin. The device
has physical dimensions which would potentially require the penetration of
numerous water conductivity laminae. This would limit the validity of the
measurement. In gravel, the number of grains included in the field of the
device is not a statistically valid sample. The problem is that discussed in
the preceeding paragraph of this review.
The most serious concern over use of the flow meter is its calibration
and the comparability of results from the flow meter with the hydraulic head--
Darcy's law method of investigation. As more experience is gained with such
devices, this problem will be resolved.
The temptation to use this device as a "cure-all" for groundwater moni-
toring will be great, especially in the hands of persons untrained in hydro-
geology. The value of these devices is in providing additional important
information for site hydrogeologic investigations. Specifically, while the
typical hydrogeologic site investigations, using hydraulic head differences
and Darcy's Law calculations, give average results over the entire site, the
use of a groundwater flow meter would provide clues to local variations in the
flow pattern and a cross-check of the results. This should help to further
define hydrogeologic conditions at investigated sites.
As a part of this investigation, WAPORA, Inc. contacted other individuals
with experience or exposure to the device. A summary of their experience as
related to WAPORA follows:
Mr. Denis Wotterdrig, New York State Department of Environmental Conser-
vation^.. Bureau of Waste Disposal, observed a demonstration of the Model 10
Dowser in October, 1980. The demonstration was held in a site where the DEC
had performed previous investigations. Soils were silty sand. He felt that
the Dowser gave a very accurate estimation of direction. The disadvantage
was that to determine velocity, one had to have a good idea of the effective
porosity of the soils.
II-H-6
-------
Mr. Greg Vanderlaan, Chief, Superfund Site Survey, U.S. EPA Region V,
Chicago, related his experience with the Dowser at the Seymore Recycling
Plant contaminated waste site in Indiana. He felt that it was a very useful
tool in the investigation of source, extent and dispersion of contamination of
groundwater. In this case, he felt that the Dowser survey was more accurate
than the hydraulic head--Darcy's Law methods also used at the site. Also
particularly useful to him was the rapidity of results compared to a hydraulic
head survey.
Mr. Joseph Fredle, Oil and Hazardous Material Coordinator, US EPA Region
V, Cleveland, used a Dowser survey to determine the location and direction
of plumes of contamination from septic systems and from old strip mines. He
felt that it was comparable to other methods, but faster in results.
Mr. Mike Rowyer, Edison Laboratojjy, US EPA MERL, Edison, New Jersey,
evaluated a demonstration of the Dowser . He also called references supplied
by Dr. Kerfot of K-V Associates. The hydrogeologists felt that great care
must be taken in the interpretation of results but that results should be
valid. Mr. Rowyer was concerned with the validity of the results until they
are proven in court actions.
TM
K-V Associates also produces a downhole Dowser probe. Specific con-
cerns in the use of this probe W&re similar to those voiced for the surface
unit. In addition, while Dowser advertises that it can be used to measure
velocity profiles in a well, this is limited by careful sampling of the effec-
tive porosity of the materials penetrated by the well, gravel packing and
grouting of the well to reduce flow between different water bearing zones
through the gravel sack, proper selection of well screen, and packing of the
well at each depth to be tested.
Objections to the use of the probe are the costs of drilling and sampling
the well, which are needed to satisfy the sampling conditions. Additionally,
some respondents stated flatly that if the packing material cannot be totally
removed from the well, it could be inconvenient and costly, or it might elimi-
nate any opportunity to prosecute groundwater contamination cases.
II-H-7
-------
I. EVALUATION AND DESIGN OF OFF-SITE SMALL WASTE FLOW
TECHNOLOGIES
Many unsewered communities will have areas where continued use of on-site
systems is not the best alternative, either for cost reasons or because on-
site systems cannot be made to work in those areas. Off-site treatment and
disposal must then be considered. There are a number of different technol-
ogies available for off-site treatment and disposal of small waste flows.
1. SINGLE PROPERTIES
Usually the first off-site option to be considered for single dwellings
or small businesses should be placement of a soil absorption system of appro-
priate design on a nearby parcel of land. If the transport distance is not
great and a suitable site is available, this will often be the least expensive
option. Site evaluation and system design will be comparable to similar
on-site technologies.
Although holding tanks are typically located entirely on-site, treatment
and disposal occurs off-site after transport by a tank truck. While holding
tanks are discouraged by health authorities and can have operation costs as
high as any other technology, they can be an effective and safe means of
wastewater disposal. However, responsibilities for timely pumping of holding
tanks and safe treatment and disposal of the wastes should be met by a person,
agency, or private organization that has adequate financial means and
technical capabilities. Despite the high operational cost of regular holding
tank pumping, the use of holding tanks can help achieve the lowest overall
cost for a neighborhood or community, if relatively few holding tanks are
required. Costs to individual property owners can be kept to a minimum by
serious efforts at water conservation or recycling, or by community subsidies
for the hauling, treatment, or disposal of the wastes.
Communities that are faced with installing or managing a number of
holding tanks for property owners would do well to consider standardizing
holding tank design. Easy-access, quick-fit hookups and reliable alarm
systems would significantly enhance holding tank operability. State agencies
that regulate on-site wastewater systems usually suggest design objectives for
holding tanks. Some agencies offer or even enforce specific design details.
2. MULTIPLE PROPERTIES OR LARGE WASTEWATER SOURCES
A wider variety of technologies is eonomically feasible when wastewater
from a number of residences or other sources must be collected for off-site
treatment and disposal.
a. Cluster Systems
Septic tank treatment and subsurface soil absorption disposal remain
competitive with other technologies in the range from 2 to over 100 resi-
dences, depending on site availability and suitability, along with other
factors. Septic tank treatment may be provided at each residence, or, after
wastewaters are collected, at a central location. The effluent is further
treated and disposed of by one of the several design variations available for
soil absorption fields. Systems with multi-family subsurface soil absorption
II-I-l
-------
fields are commonly referred to as "cluster systems." Unlike the off-site
technologies discussed below, no state-of-the-art review has been prepared on
evaluation and design of cluster systems.
Two basic approaches can be used to calculate the size of large soil
absorption systems. One approach is based on controlling the groundwater
mound that forms under groundwater recharge sources. This approach was used
to analyze the suitability of two potential cluster system sites described in
Technical Reference Document III.B., "Pickerel Lake, Michigan, Cluster System
Site Analysis."
The other approach is an extension of on-site system design. Soil perco-
lation rates are used to determine the number of square feet of trench bottom
required. This approach is suggested in the University of Minnesota's
Home Sewage Treatment Workshop (Machmeier and Hansel, 1980).
b. Land Application
Application of treated wastewater to the surface of the ground can
provide better nutrient removal than subsurface disposal, and in larger
facilities may be economically competitive.
The state of the art in evaluation and design of land application systems
has been well described in Process Design Manual: Land Treatment of Municipal
Wastewater (U.S. EPA, 1981). A special chapter in that document is devoted to
land application systems handling less than 0.25 million gallons per day.
c. Wetland Systems
Both natural and artificial wetlands can be used to treat and dispose of
wastewater. Although wetland systems are a relatively recent innovation, they
have been studied extensively.
The reader is referred to several documents for detailed information:
• The Technology Assessment of Wetlands for Wastewater Treatment (Waste
and Water International, 1982).
* Design Principles for Wetland Treatment Systems (Hammer and Kadlec,
Undated).
• Use of Wetlands for Water Pollution Control (Chan et al., 1982).
• Wetland Systems for Wastewater Treatment: Operating Mechanisms and
Implications for Design (Heliotis, 1982).
• The Effects of Wastewater Treatment Facilities on Wetlands in the
Midwest (U.S. Environmental Protection Agency and WAPORA, Inc., 1983)
d. Conventional Treatment and Discharge Systems
Small-scale designs are feasible for all of the treatment processes
conventionally used prior to discharge of wastewater to surface waters. In
small communities, selection of one process over the others is usually based
II-I-2
-------
on the closely related factors of low cost and minimal operation and main-
tenance requirements.
There is no lack of information on evaluation and design of conventional
treatment systems. Any good engineering library should have adequate
reference material on evaluation and design of such systems; therefore,
specific references on this subject are not cited here.
e. Septage Treatment and Disposal
Wastes collected from septic tanks and holding tanks have to be properly
transported, treated, and disposed of or recycled if the water quality and
public health objectives of a wastewater management program are to be met.
The state of the art for evaluation and design of septage handling is
summarized in Septage Management (U.S. EPA, 1980).
II-I-3
-------
REFERENCES
Chan, E., et al. 1982. Use of wetlands for water pollution control.
Association of Bay Area Governments, San Francisco CA.
Hammer, David E., and Robert H. Kadlec. Undated. Design principles for
wetland treatment systems (Draft). U.S. EPA, Robert S. Kerr Environ-
mental Research Laboratory, Ada OK.
Heliotis, Francis D. 1982. Wetland systems for wastewater treatment:
Operating mechanisms and implications for design. Institute of
Environmental Studies, University of Wisconsin, Madison WI.
Machmeier, Roger E., and Michael J. Hansel. 1980. Home sewage treatment
workshop. Agricultural Extension Service, University of Minnesota, St.
Paul MN.
Rezek, Joseph W. , and Ivan A. Cooper.
80-032. U.S. EPA, Municipal
Cincinnati OH.
1980. Septage management. EPA-600/
Environmental Research Laboratory,
U.S. EPA, U.S. Army Corps of Engineers, U.S. Department of the Interior, and
U.S. Department of Agriculture. 1981. Process design manual for land
treatment of municipal wastewater. Center for Environmental Research
Information, Cincinnati OH.
U.S. EPA and WAPORA, Inc. 1983. The effects of wastewater treatment facili-
ties on wetlands in the Midwest. Region V, Chicago IL.
Waste and Water International. 1982.
for wastewater treatment. U.S.
Laboratory, Cincinnati OH.
The technology assessment of wetlands
EPA, Municipal Environmental Research
II-I-4
-------
J. SITE ANALYSIS AND TECHNOLOGY SELECTION FOR ON-SITE SYSTEMS
In communities served by on-site wastewater treatment systems, problems
with existing systems must be identified. A systematic approach to isolating
problem areas, identifying specific problems, and selecting the appropriate
technology to solve the problem is presented in Figure II-J-1. The Decision
Flow Diagram is divided into the following sections: 1) Phase I Information
Gathering, 2) Sanitary Survey, 3) Definition of Problem, 4) Site Specific
Analysis, and 5) Technology Selection.
Phase I Information Gathering includes reviewing existing or easily
obtainable data (for more detail see Appendix A, Region V Guidance - Site
Specific Needs Determination and Alternative Planning For Unsewered Areas).
Data from Phase I can usually be obtained without going on-site and is useful
for isolating potential problem areas.
The Sanitary Survey involves talking with individual homeowners about
their on-site systems. The information generated is useful for defining
problems with individual systems. After specific problems are defined the
site specific analysis section of the decision flow diagram provides for
various tests and inspections to find the source of the problem and to provide
enough background information to select the most appropriate technology.
The Decision Flow Diagram provides for systems that do not meet current
codes. For example, consider a septic tank that is found to be smaller than
current requirements. If the septic tank is in satisfactory condition and
operating properly, no additional work is recommended.
The Decision Flow Diagram cannot account for all situations that may be
encountered in the field and should, therefore, be used as a guide along with
common sense to determine the proper solution for on-site wastewater treatment
system problems. The notes following Figure II-J-1 correspond to numbers
listed on the decision flow diagram.
II-J-1
-------
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II-J-2
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-------
NOTES
1. If, through previous experience, the cause of the problem can be identi-
fied, the remaining steps can be bypassed by correcting the problem.
2. State standards for minimum setback distances should be used unless a
hydrogeologic (or other) reason exists to use a larger distance.
3. In using contaminated wells as a criterion for delinating sewer service
areas, only data from protected wells should be used.
4. Odors can come from a properly functioning septic tank/soil absorption
system. Relocation of vent may solve the problem.
5. Shoreline scan should be repeated to ensure that plumes are found.
6. Well samples should be taken several times at various intervals to ensure
accurate results.
7. If house drains are likely to be clogged, snaking drains may solve
problem. Note: monitoring of watermeter is required after installation.
8. Septic tank and sewer inspection to include: excavation; pumping;
inspection for size, structural integrity, outlet and baffle condition;
rodding house and effluent sewers; measuring distance and direction to
SAS using snake.
9. If septic tank and/or sewers (to and from septic tank) need replacement,
and additional work on drainfield is required, follow "no" route and
investigate other factors before replacing septic tank and/or sewers.
This process will avoid replacement of septic tank/sewers when entire
system is not functional.
II-J-3
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K. GEOTECHNICAL INVESTIGATIONS FOR CLUSTER DRAINFIELDS
1. INTRODUCTION
Soil characteristics and surface and groundwater hydrology are the most
important factors influencing the feasibility and performance of cluster
drainfields. These characteristics must be evaluated throughout the site
selection and evaluation process in order to arrive at a reasonable estimate
of the feasibility and appropriate design criteria for a particular site.
Soil cannot be tested or evaluated as can other engineering materials, such as
steel, because it varies foot by foot both horizontally and vertically. The
designer must conduct his evaluation and selection of design criteria with
this attitude in mind. Simplifying assumptions must be made, average values
selected, and limitations of data gathering, evaluation, and design criteria
selection techniques kept in mind throughout these investigations.
In the analysis of soil characteristics and surface and groundwater
hydrology, certain values should be estimated and quantified by field and
laboratory testing when necessary. . These values would be included in the
following categories:
• Horizontal permeabilities - the rates for each distinctive soil layer
at which water will move laterally from the drainfield
• Vertical permeabilities - the rates for each distinctive soil layer at
which water will move downward from the drainfield
• Depth to water table - the distance below the ground surface at which
free water is encountered; also a measure of the allowable rise in the
water table that causes horizontal movement of the groundwater below
the drainfield
• Depth to aquitard - the distance below the ground surface at which a
layer is encountered that allows only a minimal passage of water
downward; also a measure of the thickness of permeable material
through which horizontal flow will occur
• Slope of the water table - the gradient of the pressure which indi-
cates flow direction and when analyzed with the thickness of the
saturated material and its hydraulic conductivity provides a measure
of the present horizontal flow rate
• Slope of the aquitard - the slope of the underlying material which may
determine the slope of the water table and groundwater flow direction.
In addition to estimates of criteria for the specific site itself, esti-
mates of adjacent areas should be developed also to ascertain the effect of
the applied wastewater.
II-K-1
-------
2. PHASES OF THE GEOTECHNICAL INVESTIGATION
The investigations are carried out usually in three phases; the second
and the third phases are dependent upon the first. The individual phases are
outlined as follows:
a. Preliminary Site Investigation
The objective is to establish the general feasibility of the area for
possible cluster drainfield sites. The primary source of information for the
area assessment should be the detailed soil survey prepared jointly by the
USDA Soil Conservation Service (USDA-SCS) and the state experiment station.
These soil surveys can help to evaluate the suitability of a specific soil
series for septic tank drainfields. It must be noted, however, that the
survey's rating system is based on limitations. For example, although some
soils may be rated "severe," workable systems may be designed but at a greater
expense. Therefore, specific soil characteristics must be examined closely in
order to arrive at suitable classifications for various drainfield designs.
Along with the soil survey information, topography, land use, and geology
should be utilized also to optimize site selection. Topographic information
is available from USGS quadrangles. More detailed information may be avail-
able from the USGS, local planning agency, community, or landowners. Land use
information can be obtained from aerial photographs or from a windshield
survey. Geological information can be obtained from special USGS reports,
state or local reports, and well logs available from the local or state per-
mitting agency or state USGS offices. Finally, landowners' knowledge of their
property, often extensive in rural areas but also often ridden with gross
misconceptions, should not be overlooked.
From the preliminary analyses of soils, topography, land use, and geo-
logy, a general site survey can be conducted. Cross-sections should be drawn
through areas of greatest interest so that materials below the ground surface
can be visualized and estimates can be made for the criteria enumerated in the
preceding discussion. Then, the most promising sites could be investigated
further.
At this point, estimates should be made of the type of drainfield that
could function properly. The preliminary design must account for the mounding
effect, a horizontal movement of water from under the drainfield. Sites with
a limited depth to an aquitard or groundwater or low horizontal permeability
may require a long, narrow drainfield rather than a square drainfield. A
cluster drainfield may function on a particular site only if some means of
artificial drainage is provided. Other designs might be considered also.
The most feasible sites and preliminary designs would be included in the
cost-effective analysis and compared with other alternatives for wastewater
treatment. If the cluster drainfield alternative is viable, the second phase
of the geotechnical investigation would be implemented to determine critical
soil and groundwater values.
II-K-2
-------
b. Field Testing Program
Following the selection of the most suitable site(s), more detailed
information may be necessary for preliminary design criteria and for assess-
ment of the impact of the cluster drainfield on the environment. Groundwater
mounding methods and flow effects should be selected prior to field investi-
gations. The values necessary for the selected methodology can then be
designed into the field investigation program.
The field investigation program should be designed to realistically
account for the non-homogeneity of the soil mass and should neither grossly
under- or over-estimate soil values and groundwater conditions. Thus, samp-
ling methods that encompass the greatest soil mass would probably generate the
most reasonable values. The most inexpensive and convenient testing proce-
dures generally involve very small soil samples, and are, therefore, least
representative of the actual soil body since a multitude of tests are not
included (Reeve, 1965).
Where a detailed soil survey is not available or where the soil survey
indicates considerable variability within a mapping unit, the contiguous lands
and the land on the site should be mapped by a competent soil scientist fami-
liar with the area. The USDA Soil Conservation Service will, cost and sche-
duling permitting, perform the mapping for requesting landowners, or will
provide names of individuals who can provide the service if they cannot. The
work is normally mapped on aerial photographs at a scale of 4 inches = 1 mile.
If aerial photographs of a different scale were to be provided, for example 1
inch = 400 feet, they would be more useful, especially if the soil boundaries
were variable.
Ideally, the soil borings and testing would be conducted by a firm that
performs borings for structural purposes and for aquifer testing for water
well purposes. Soil test firms generally collect small soil samples, visually
classify soil material, and install piezometers. Well drilling firms
generally visually classify soil material and conduct field tests on the
saturated material. Frequently, the soil investigation program is limited by
the equipment and experience of the drilling firms in the area.
The number and spacing of borings on a particular site would depend upon
the complexity of the soils, the margin of suitability , and the contributing
flow. While the actual number of borings may range from one to ten, three
would usually suffice for most sites. At least one of the borings should be
conducted with continuous split spoon sampling to identify any layers of
limiting vertical permeability that would function as an aquitard (per-
meability less than the application rate). The soil material throughout the
boring should be visually classified and blow counts kept on the split spoon
sampling. The boring should be continued well down into the permeable
material below the water table so that the area contributing to horizontal
flow can be defined.
Piezometers should be installed in the borings in order to define the
water table. Plastic well or piezometer screens perform best, along with
plastic (PVC or CPVC) casings. The piezometers should be placed in both the
upper and lower aquifers if a well-defined aquitard is present. The flow
situation would be considerably different if water were moving upward from the
II-K-3
-------
lower aquifer than if it were moving downward from the upper aquifer. Dif-
ferent water levels in the piezometers would define the direction of movement.
The elevations of the water table in the piezometers should be established by
a level survey to within an accuracy of 0.1 feet difference between the piezo-
meters. Also, the elevation of surface water bodies in the area should be
determined by the level survey or by topographic maps. The slope of the
aquitard can be estimated from the borings and from level survey information.
Piezometers can be pumped out and utilized for obtaining water samples,
and should be pumped until clear water is obtained and a sample taken. The
sample should be tested primarily for nitrates and phosphorus, the nutrients
of greatest concern. A complete chemical analysis should be conducted where
groundwater chemistry is an identified concern.
Numerous testing procedures, which have been developed for determination
of soil hydraulic properties, vary widely in equipment needs, bulk of soil
tested, testing accuracy and reproducibility, and time required for testing
(Luthin, 1957; Kirkham, 1965; U.S. EPA, 1977). A list of some of these
procedures is provided in Tables 1 and 2. A soil test that determines the
properties of a small volume of soil must be extrapolated to the larger soil
mass. The approximations involved in doing that do not warrant extensive and
expensive tests for accurate results. Certain tests are designed for specific
soil materials and would not work in soil materials of greatly different
textural classes. Also, the soil testing procedures are generally classified
into above-the-water-table and below-the-water-table conditions. Some tests
are applicable only where a considerable depth of saturated permeable material
is located.
c. Analysis of Groundwater Mounding and Discharge
In order to assess whether an adequate distance between the water table
and the bottom of the drainfield would exist under loading conditions, a
method of predicting the water table rise, or conversely, of selecting design
criteria for the drainfield, is necessary. Several means for conducting the
analysis are available. Probably the most convenient, and the most conserva-
tive, is the Hooghoudt or elipse equation for two-dimensional flow. It can be
derived for a level aquitard and a sloping aquitard and its derivation re-
quires the assumption of an outflow ditch or drain tile. Several methods that
model simple groundwater systems are available, including some with graphical
and computer-assisted solutions (Spiegel, 1975; Bianchi and Muckel, 1970; U.S.
EPA, 1977). Generally, the estimation of hydraulic conductivity entails
considerable error and rigorous solutions are not justified. The modeling
analysis should be evaluated against design criteria utilized and modeling
techniques employed until a functioning cluster drainfield is developed. The
cost analysis for this drainfield design can then be compared with other
alternatives for sewage treatment.
Frequently overlooked in the analysis of the cluster drainfield is the
effect it would have on the groundwater discharge locations and flow rate. In
most areas the change may be negligible; nevertheless, an analysis of the
impact of drainfield on groundwater discharge should be conducted if only in a
qualitative manner. Occasionally mitigative measures must be employed to
minimize the impact of greater groundwater discharge or of altered discharge
locations.
II-K-4
-------
Artificial drainage such as drainage wells or draintile may be necessary
for a cluster drainfield to function properly. Draintile is preferred if a
gravity outlet is available. In some situations, intercepting natural ground-
water would be necessary to ensure satisfactory functioning of a cluster
drainfield. Thus, potential sites should not be eliminated from consideration
due to depth to groundwater or aquitard limitations.
3. Example Site Analyses
Three hypothetical sites, and boring programs for each site, are de-
scribed herein. The first site is a 50-acre outward terrace with an eleva-
tion about 30 feet above an adjacent lake. The USDA-SCS identifies the soils
on the site as nearly uniformly medium sands with a permeability of 6-20
inches per hour. Soil properties that cannot be estimated are depth of medium
sands and potential of aquitards. The depth to groundwater and its flow
direction (slope) could be defined also. One soil boring would suffice for
the site, assuming that the medium sands are deep and the water table eleva-
tion is slightly above the lake elevation. The boring should be performed
with a hollow-core auger and continuous split spoon sampling. The Hooghoudt
equation for two-dimensional flow could show conservatively that the mounding
effect would be no problem.
The second site is similar to the first but the soils have a lower per-
meability rating by USDA-SCS standards, two-six inches per hour. Wells from
the area indicate variable depths to an aquitard, possibly discontinuous. The
elevation difference between the land surface and the lake is about 25 feet
and the distance to the lake is about one-fourth of a mile. The boring pro-
gram would consist of three borings spaced equilaterally on the site extending
to a depth 20 feet below the water table, or five feet into an aquitard.
Continuous split spoon sampling would be conducted in one boring, and periodic
split spoon samples taken at perceived soil texture changes in the other two
borings. A limited number of double-tube tests for horizontal and vertical
permability would be conducted below the expected bottom of the drainfield.
At the piezometer location most suitable for a drainfield, a four-well per-
meability test would be conducted. Three additional peizometers would be
installed for the test. The data from these tests would then be interpreted
and an analysis of the mounding effect conducted. Different configurations of
drainfields would be investigated until a satisfactory arrangement is identi-
fied.
A third site has three soil series mapped by the USDA-SCS, and soil
textures range from silt loams to sands and gravels in apparently random
patterns. One mapping unit is a complex of the other two mapping units.
Within 600 feet on opposite sides of the site area small ponds. The elevation
difference between the ponds is five feet, and the ground surface on the site
is about ten feet above the lower pond water surface. First, the field
investigation should consist of a more detailed soil mapping on a 1":400'
scale aerial photograph performed by a locally qualified soil scientist. A
boring program can be devised from the detailed mapping. Approximately ten
borings and piezometers may be necessary to define the soil material and the
water table surface. Double-tube permeability measurements could be conducted
in the various soil layers above the water table as the borings are conducted.
Below the water table the four-well or, if the saturated sand and gravels are
of sufficient thickness, aquifer and recovery tests or a slug test could be
II-K-5
-------
conducted. The effect of septic tank effluent application to the drainfield
would probably indicate the need for artificial drainage. The analysis should
concentrate on the feasibility of providing drainage and on the drainfield
configuration. The irrigation test may be an alternative for evaluating
limiting vertical permeabilities and effective horizontal permeability.
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II-K-9
-------
REFERENCES
Johnson Div., UOP. 1972. Groundwater and wells. St. Paul, MN.
Bouwer, H. and R. C. Rice. 1976. A slug test for determining hydraulic
conductivity of unconfined aquifers with completely or partially pene-
trating wells. Water Resources Research 12:423-428.
Bouwer, H. 1970. Groundwater recharge design for renovating wastewater. In:
Proceedings of the American Society of Civil Engineers, 96:SA1:59-73.
Skaggs, R. W. 1976. Determination of the hydraulic conductivity-drainable
porosity ratio from water table measurements. Transactions of the
American Society of Agricultural Engineers, pp 73-80, 84.
Hoffman, G. J. and G. 0. Schwab. 1964. Tile spacing prediction based on
drain outflow. Transactions of the American Society of Agricultural
Engineers, pp 444-447.
Leach, L. E., C. G. Enfield, and C. C. Harlin, Jr. 1980. Summary of long-
term rapid infiltration system studies. EPA-600/2-80-165. U.S. EPA,
Robert S. Kerr Environmental Research Laboratory, Ada OK.
Boersma, L. 1965a. Field measurement of hydraulic conductivity below a water
table. In: Methods of soil analysis, Part 1. American Society of
Agronomy Monograph 9 Madison WI, pp 222-233.
Boersma, L. 1965b. Field measurement of hydraulic conductivity below a water
table. In: Methods of soil analysis, Part 1. American Society of
Argonomy Monograph 9 Madison WI, pp 234-252.
Bouwer, H. 1964. Measuring horizontal and vertical hydraulic conductivity of
soil with the double-tube method. Soil Science Society of America
Proceedings 28:19-23.
Grover, B. L. 1955. Simplified air permeameters for soil in place. Soil
Science Society of America Proceedings 19:414-418.
Kirkham, D. and J. E. Adams. 1959. Apparatus for measuring diffusion
coefficients of soil in place. U.S.A. patent No. 2,913,397, Nov. 24,
1959.
Kirkham, D. and B. L. Grover. 1960. Apparatus for measuring fluid per-
meability of porous materials. U.S.A. patent No. 2,349,766, Aug. 23,
1960.
Snell, A. W. and J. van Schilfgaarde. 1964. Four-well method of measuring
hydraulic conductivity of the soil. Transaction of the American Socity
of Agricultural Engineers 7:38-87,91.
Klute, A. 1965. Laboratory measurement of hydraulic conductivity of
saturates soil. In: Methods of soil analysis Part 1. American Society
of Agronomy Monograph 9 Madison WI, pp 210-221.
II-K-10
-------
Schmid, W. E. 1967. Field determination of permeability by the infiltration
tests. In: Permeability and capillarity of soils. ASTM Special Publi-
cation 417, ppl42-159.
Davis, S. N. and R. S. M. DeWeist. 1966. Hydrogeology. John Wiley and Sons,
Inc., New York, NY.
Kirkham, D. 1965. Saturated conductivity as a characterizer of soil for
drainage design. In Drainage for efficient crop production conference
proceedings. American Society of Agricultural Engineers.
Reeve, R. C. 1965. Characterizing soil properties for drainage design—art
or science? In: Drainage for efficient crop production conference
proceedings. American Society of Agricultural Engineers, pp21-23.
Donnan, W. W. 1959. Field experiences in measuring hydraulic conductivity
for drainage design - a symposium. Agricultural Engineering 40-270-273,
280.
Luthin, J. N. 1957. Drainage of agricultural lands. American Society of
Agronomy.
U.S. EPA. 1977. Process design manual for land treatment of municipal waste-
water. US EPA, US Army COE, and USDA. EPA 625/1-77-008.
Spiegel, Z. 1975. Hydrology In: Wastewater resource manual. The Irrigation
Association, pp 2A2/1-2A2//11.
Bianchi, W. C. and D. C. Muckel. 1970. Groundwater recharge hydrology USDA-
ARS Publication No. 41-161 [as referred to in US EPA (1977)].
II-K-11
-------
L. IMPACTS OF WATER CONSERVATION ON ALTERNATIVE TECHNOLOGIES
1. INTRODUCTION
Flow conservation in individual residences directly impacts on-site
wastewater treatment and disposal systems. However, the nature and extent of
these impacts is not yet well defined. Existing literature on the subject is
scarce, although ongoing research promises to fill in some of these gaps. One
reason for the lack of information is that until the late 1960's and early
1970's, not much attention had been given to flow conservation because of lack
of incentive. With the benefits now realized, such as lower costs for water
supply and heating, more attention will be given to the effects on wastewater
treatment and disposal.
2. EXISTING LITERATURE
Existing literature indicates that favorable impacts for on-site systems
can be expected from flow conservation. Baker (1980) takes a total system
approach in performing a cost analysis for households with and without flow
reduction in the form of air-assisted toilets (0.5 gal/flush) and air-assisted
showers (0.5 gpm). For a family of four, the reduced flow is assumed to allow
a reduction in drainfield area from 750 ft2 to 280 ft2. This result is based
on a design infiltration rate of 0.6 gpd/ft2 and not on local codes that may
not allow such a reduction. With the reduction of drainfield area and the
reduction of energy required for shower water as the major factors, Baker
shows a household with flow reduction devices to have a lower annual system
cost than a household without flow reduction. The effect anticipated, there-
fore, is beneficial in terms of annual cost of the overall system and reduc-
tion of the size (or the extension of the life) of the drainfield.
Bennett (1975) indicates that flow reductions of 40% would reduce the
cost of an average septic tank/soil absorption system by about 23%. The
implication of the lower costs is that not as much treatment is required for a
given system with reduced flows. If reduced flows result in smaller soil
absorption systems for acceptable soils, perhaps flow reduction can be used in
conjunction with marginal soils to make them acceptable for on-site disposal,
or with failed systems for rehabilitation.
3. RESEARCH
The possibilities of rejuvenation are the subject of two research
projects currently underway. Purdue University (Hudkins, 1980, personal com-
munication) is investigating a number of on-site systems in Indiana that have
failed and will be recommending flow conservation options or alternative
treatment system options depending on the specific site conditions. Results
from this study are not expected until the latter part of 1981. The
Pennsylvania State University (Fritton, 1980, personal communication) is
involved in a similar research project that includes monitoring water consump-
tion and soil absorption system operations prior to implementation of a
rehabilitation strategy. The systems will continue to be monitored after
installation of flow conservation devices or alternate drainfields so that the
effects of flow reduction and drainfield resting can be determined. Results
from this project should be available in October 1981.
II-L-1
-------
4. POSSIBLE EFFECTS ON SEPTIC TANKS
Water conservation will have some obvious impacts on the septic tank. One
of these impacts will be an increase in the detention time of the wastewater.
Theoretically, this increased detention time will allow better settling of
solids and possibly improved digestion of pollutants. Flow reduction devices
also reduce somewhat the hydraulic surge loads that conventional fixtures
place on a septic tank. Smaller surges should reduce the mixing within the
septic tank, thus reducing the possibility of solids carry-over, especially
when the tank is ready for pumping.
For existing septic tanks not meeting current codes for size (smaller
than standard size), the effect of flow reduction may be to increase the
detention time to a point comparable to a standard size tank without flow
reduction. Thus, savings could be realized by not having to replace an under-
sized tank. Undersized tanks would then have the potential for adequate treat-
ment, while properly sized tanks could provide a somewhat better effluent.
Another effect of reduced flows is an overall increase in temperature of
the wastewater. An increase in temperature is particularly evident when toilet
flushing is reduced significantly. Table II-L-1 (Baker, 1980) shows flow rates
with conventional and flow-reduction fixtures along with the expected tempera-
tures for each use.
TABLE II-L-1. TYPICAL FLOW RATES AND TEMPERATURES FOR HOUSEHOLD WATER USES
Use
Toilet
Bathing
Laundry
Dishwasher
Kitchen (including
Conventional
flow
(gpd)
100
80
35
? 27
Reduced
flow
(gpd)
10
10
35
27
Temperature
(F°)
Ambient
105
105
140
105
dishwasher)
Lavatory
Utility
TOTAL
255
95
105
105
The figures were based on a family of four with air-assisted showers and
air-assisted toilets used to obtain the reduced flows. Figure II-L-1 shows the
temperature of the wastewater as a function of ambient water temperature for
conventional flows (255 gpd) as well as for reduced flows (95 gpd). The
increase in temperature could theoretically mean an increase in biological
activity within the septic tank. A higher digestion rate in the tank could
II-L-2
-------
10
100
a:
ui
a.
3E
UJ
I-
UJ
o
CE
o
en
90
80
I
40 50 60
WATER AMBIENT TEMPERATURE (°F)
70
Figure II-L-1. Wastewater temperature vs.
ambient water temperature.
II-L-3
-------
mean less frequent pumping. However, this hypothesis must be tested along with
testing for detrimental effects such as poorer settleability as a result of
increased temperatures and increased gas generation.
Although increased detention time and temperature appear to be obvious
effects of flow conservation on septic tanks, the impacts on treatment have
not been scientifically proven. Similarly, soil absorption systems are known
to receive less wastewater, but the impact on the quality of the effluent or
the life of the system has also not been proven.
5. POSSIBLE EFFECTS ON SOIL ABSORPTION SYSTEMS
The most obvious effect of flow reduction is the decrease in hydraulic
load to the soil absorption system. Because systems are sized on the basis of
hydraulic load, a reduction in field size might be appropriate. A reduction in
field size would be a tangible indicator for cost reductions of on-site
systems.
Some states, such as Minnesota, allow a reduction in the size of the soil
absorption system when wastewater flow is reduced (Machmeier, 1979). Soil
treatment area can be reduced by about the same percentage as the reduction in
flow. Minnesota requires that the amount of sewage applied to the soil be
measured through the installation of a water meter or a cycle counter for well
pumps. Many regulatory authorities do not allow a reduction in field size
because they question the permanence of the flow-reduction devices or because
they do not see the associated cost savings as being significant.
Another way of looking at the benefits woul be to consider the life of a
soil absorption system in terms of total number of gallons treated. If a soil
absorption system treats 255 gpd for 20 years, the total number of gallons
treated would be 1,861,500 gallons. A flow-reduction system that handles 95
gpd would require a system life of 54 years in order to treat 1,861,500
gallons. This linear extrapolation is only an approach to assign economic
benefits for soil absorption systems receiving reduced flows. No empirical or
proven theoretical relationship exists relating hydraulic or organic loading
to the useful life of a soil treatment system.
Organic solids loading to a soil absorption system may be low because of
the increased detention time in the septic tank. On the other hand, the solids
loading may remain the same because the total amount of pollutants entering
the system will not be altered by reducing flows. Pilot studies or research,
as mentioned earlier in this section, would help answer questions relating to
such topics as solids loading to soil absorption systems. If the quantity of
total dissolved solids in the supply water is high, the reduction in water use
would definitely lower the solids loading to the soil absorption system.
6. CONCLUSIONS AND RECOMMENDATION
Many unanswered questions exist regarding the impact of water conserva-
tion on on-site treatment and disposal systems. Beneficial impacts of flow
conservation on on-site systems appear likely, but testing and additional
research is needed to confirm existing hypotheses. The following objectives
should be considered as part of future research on flow conservation effects
on on-site treatment systems in order to assess the feasibility and economic
impact of flow reduction:
II-L-4
-------
• Effects on soil absorption systems (size, loading, effective life),
• Effects on septic tanks (increased detention time, increased tempera-
ture, reduced surge loads, reduced mixing),
• Need for metering,
• Applicability to marginal soils,
• Applicability to failed systems,
• Effects on on-site systems not soil dependent (fixed film, package
aeration, etc.), and
• Effects on overall system costs and effective life.
II-L-5
-------
REFERENCES
Baker, L.K. 1980. The impact of water conservation on on-site wastewater
management. Weatherby Associates, Inc., Jackson CA.
Bennett, E.R. 1975. Impact of flow production on on-lot sewage systems.
Proceedings of a conference on water conservation and sewage flow reduc-
tion with water-saving devices, April 8-10, 1975. The Pennsylvania State
University, University Park PA.
Fritton, D. D. The Pennsylvania State University Department of Agronomy.
University Park PA. Personal Communication, 16 December 1980.
Hudkins, S. Project Coordinator, Purdue Univeristy Agronomy Department. West
Lafayette IN. Personal Communication, 15 December 1980.
Machmeier, R.E. 1979. Town and country sewage treatment. Extension Bulletin
304. University of Minnesota, Agricultural Extention Service, St. Paul
MN.
II-L-6
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CHAPTER III
USE OF SOILS DATA
-------
A. SOILS RELATIONSHIPS STUDY
1. INTRODUCTION
Soil characteristics can be used to explain the performance of existing
on-site sewage disposal systems and to predict the performance of new and
future systems. Explanations and predictions may be based either on
hypothetical relationships or locally verified relationships between soil
characteristics and system performance. For planning-level decisions on
developed and undeveloped properties and for site-specific decisions on
undeveloped properties, the use of hypothetical relationships would be
appropriate. For site-specific decisions relevant to existing private sewage
disposal systems, however, the use of actual performance data and on-site
soils information is imperative in order to maximize the service life of rural
wastewater management systems and to optimize potential cost-effectiveness
gains of these systems in comparison to sewers or other off-site facilities.
The benefits and limitations of applying soils data, based upon
hypothetical relationships between on-site system performance and soil
characteristics will be examined subsequently within the context of soil
surveys and soil potential studies. Soil surveys are valuable wastewater
management planning tools, containing information that is particularly useful
in making preliminary estimates of new system feasibility and in designing
field investigation programs. For site specific decisions, however, soil
survey data, particularly soil limitation ratings, may preclude on-site sewage
treatment techniques that are feasible and cost-effective. In effect, soil
surveys recognize site limitations including low soil permeability and shallow
depth to seasonal high groundwater as problems to avoid.
The use of soil potential ratings refine on-site wastewater management
planning by recognizing the feasibility and cost-effectiveness of small waste
flows techniques that may be used to overcome limiting site characteristics.
This recognition, incorporated into soil potential indices, represents a
departure from soil limitation ratings. Like the soil survey, however, soil
potential data do not provide site-specific information that is essential to
detailed decision making. Soil potential data effectively recognize site
limitations as problems which can be overcome.
Empirical soils data are gathered, assessed, and retained in recognition
of the fact that detailed wastewater management decisions must be based upon
locally verified relationships, not hypothetical relationships, between on-
site system performance and soil characteristics. The empirical approach
recognizes that actual system performance does not always correlate well with
soil limitation ratings. It further recognizes that system performance is not
only influenced by local soil characteristics but also by other factors
including system design, construction practices, usage, condition, and main-
tenance. In favorable soils, sub-optimum conditions in these other factors
will not usually result in on-site system failures. In marginal soils, sub-
optimum conditions will need to be improved in order to avoid malfunctions.
In unfavorable soils, these conditions will need to be markedly improved in
order to sustain efficient on-site sewage treatment. Some soils are so un-
III-A-1
-------
favorable that no technique will be feasible and cost-effective. It is noted,
however, that the empirical approach does not automatically recognize a soil
limitation as a problem. Instead, it serves to probe reasons for system
malfunctions, thereby suggesting corrective measures for existing systems that
have failed and new or future systems that have the potential to fail under
similar conditions.
2. USE OF SOIL SURVEYS IN RURAL WASTEWATER FACILITIES PLANNING
Since their first application to urban land use planning in the early
1960's, soil surveys have proven useful to public officials in the general
siting of septic tank absorption fields. As basic land resource inventories,
soil surveys provide information that cannot be obtained readily elsewhere.
However, limitations inherent in their preparation and interpretation restrict
the extent to which soil survey data, particularly soil performance ratings,
may be applied in the planning and designing of on-site wastewater management
systems. The ratings of soils for subsurface wastewater absorption, as pre-
sented in soil surveys, represent an assumed relationship between the per-
formance of soil absorption systems and the soil characteristics upon which
system performance depends. In many cases, this relationship is assumed to be
valid. However, the relationship is not valid in enough cases to make it
absolute and render the soil suitability ratings firm. Therefore, the use of
soil surveys is optimized in the general planning and siting, rather than the
detailed planning and design of on-site systems.
a. The Recent* Soil Survey
Soil surveys are prepared by the USDA Soil Conservation Service in
cooperation with state agricultural experiment stations, and contain all soil
maps of the survey area, descriptions of the soils, and interpretations for
the use and management of the soils.
With the exception of Illinois, soil surveys are available for most
counties in the midwestern states (see Table III-A-1). Current plans of the
Soil Conservation Service call for completion of all new county soil surveys
by 1997 (by telephone, Lloyd Wright, SCS, USDA, Washington, B.C., 13 January
1981).
TABLE III-A-1. APPROXIMATE PERCENTAGE OF COUNTIES BY STATE IN REGION V WITH
COMPLETED SOIL SURVEYS AS OF 1978
Region V State Percentage of Counties Surveyed
Illinois 30
Indiana 83
Michigan 83
Minnesota 56
Ohio 72
Wisconsin 71
Source: USDA SCS 1978.
* Assumed to address non-agricultural land uses (e.g., septic tank absorption
fields).
III-A-2'
-------
Olson (1964) stated that the objectives of a soil survey are to:
• determine the important characteristics of soils;
• classify soils into defined types and other classifiable units;
• establish and plot on maps the boundaries among different kinds of
soil;
• correlate and predict the adaptability of soils to various uses.
The soil survey is most effectively employed in reviewing the suitability
of large land areas, such as plots and subdivisions, for wastewater disposal.
The suitability of individual lots for sewage disposal is best determined
through on-site evaluation rather than through use of the soil survey alone
for reasons discussed later in this section.
Standard data contained in recent soil surveys that are important in
small wastewater flows planning include land form, relief and drainage; parent
material; soil profile characteristics; depth to groundwater; and depth to
impermeable layers.
Both general and detailed soil maps are included in soil surveys.
General soil maps are prepared in the field at a scale of one inch to the mile
or less, with map units consisting usually of soil associations. At the
community planning stage, a generalized soils map is essential for determining
the potential suitability of septic tank-soil absorption systems (USEPA,
1980). Detailed maps, which delineate types or phases of soil series, soil
complexes, and undifferentiated units, are usually published at a scale of
3.17 (approximately 4) inches to the mile. Detailed soil maps are super-
imposed on aerial photographs to show the location of various land uses and
natural terrain features (see Figure III-A-1). These maps enable one to
assess soil permeabilities and soil purification capabilities in general
terms. Mellen (1975) noted that the accuracy of soil survey maps vary,
depending on the location, due to the soil complexity, detail of the exami-
nation, scale of the base map, and the skill and experience of the soil
mapper.
In an effort to satisfy the fourth objective of soil surveys, soil
scientists make behavior predictions on the basis of soil properties such as
permeability, water table fluctuation, and slope to determine the capacity of
soil to absorb sewage effluent. These behavior predictions are manifest in
soil limitation ratings.
1) Soil Limitation Ratings
Over the past 16 years, soil survey interpretations for non-farm land
uses have included a rating of soils by limitations. The classifications used
in rating soil limitations, as described in the National Soils Handbook (USDA,
SCS, 1978), are defined as "slight", "moderate", or "severe" (Rogoff, 1979):
• Slight limitations are those which present no more than minor problems
for the intended use and which can be overcome easily
III-A-3
-------
Figure III-A-1. Detailed soils map
III-A-4
-------
• Moderate limitations for the intended use can be overcome or modified
by special planning and design, or maintenance for satisfactory
performance
• Severe limitations are difficult and costly to overcome, requiring
major soil reclamation, special designs, or intensive maintenance.
Soil limitation ratings are not quantitative. They are indicators of the
kind of problem and degree of difficulty that may be confronted in the design
of an effective wastewater treatment and disposal system. Because soil
mapping units are not always homogeneous, the limitation classification is a
good guide to areas in which more detailed investigation may be necessary
(#6). It is noted that limitation ratings for septic tank drainfields are
based only on conventional bed or trench designs.
The soil characteristics used in deriving soil limitation ratings are
listed in Table III-A-2. They are based on a drainfield whose bottom surface
TABLE III-A-2. SOIL LIMITATIONS RATINGS USED BY SCS FOR SEPTIC TANK/SOIL
ABSORPTION FIELDS
Property
USDA Texture
Flooding
Slight
None,
Limitations
Moderate
Rate
Severe
Ice
Common
Restrictive
Feature
Permafrost
Floods
Depth to Bedrock,
Protected
>72
40-72
>40
Depth to Rock
in.
Depth to Cemented
Pan, in.
Depth to High
Water Table, ft
below ground
>72
>6
40-72
4-6
>40
>4
Depth to
Cemented Pan
Ponding,
Wetness
Permeability,
in./hr
24-60 in. layer
layers >24 in.
Slope, percent
Fraction >3 in. ,
percent by wt
2.0-6.0 0.6-2.0 >0.6
>6.0
0-8 8-15 >15
>25 25-50 >50
Slow Perc. Rate
Poor Filter
Slope
Large Stones
Source: U.S. EPA, Region V
III-A-5
-------
is located 2 ft. (0.6m) below the soil surface (U.S. EPA Region V). Each soil
characteristic has the potential to limit the capabilities of a soil mapping
unit to the severe classification. This represents a distinct disadvantage in
light of small wastewater technologies available (see Table III-A-3) to over-
come these and other limiting soil characteristics.
TABLE III-A-3. ALTERNATIVES TO STANDARD SEPTIC TANK-SOIL ABSORPTION SYSTEMS
Aerobic Alternative
system fields
Steep slopes X
Shallow bedrock X
Space limitations X
High water table
Iron & managanese
in water X
Soil permeability X
No permeability X X
Re-use water X
Water limited
Lot size
Enclosed
system
X
X
X
X
X
X
X
Grey
Evapotrans- water
piration system
X
X
X
X
X X
X X
X X
X
X
X X
Water
conser-
vation
X
X
X
X
X
X
X
X
X
X
Source: Brian Duff, 1977
The advantages and disadvantages associated with the use of soil limita-
tion ratings in wastewater management planning are discussed below.
2) Advantages of Soil Survey Data
Some key advantages to using soil survey data in wastewater management
planning are listed below:
• Soil surveys represent a valuable source of areawide soils information
which, if understood and used properly, have multiple planning and
engineering uses
• Detailed soil maps are used in the preliminary selection of sites for
subsurface absorption systems
III-A-6
-------
• Soil surveys provide developers with a means for determining soil use
before they purchase land. In effect, this enables developers to
choose areas where odds are with, not against, success (Olson, 1964)
• Soil surveys indicate location of soils with impermeable horizons
through which water does not readily pass
• Detailed soil maps illustrate site conditions that can be expected
during field investigation of potential small wastewater flows sites.
Expected conditions help determine equipment and time requirements for
conducting field investigations
• Soil survey information enables health officials and small waste flows
design specialists to quickly determine courses of action in problem
areas
• A soil survey provides a method to determine readily whether a pro-
posed subdivision can be expected to pass the soils evaluation test
and approximately what percentage of lots can be expected to be served
satisfactorily by on-site sewage disposal systems (Clayton, 1975)
• The use of information in soil surveys makes it possible to overcome
most of the limitations of the percolation test, thereby increasing
test value, as illustrated below (Mellen, 1975):
- The soil map will permit an assessment of site suitability or
limitations for the different kinds of soils regardless of the time
of year at which the request for determination is made.
- Interpretations of the soil mapping unit will indicate whether or
not the soil at a particular site is subject to an intermittent high
water table. This will avoid the criticism of variability of the
percolation tests, which results from the tests taken at different
seasons of the year.
- The suitability of a site can be based on the performance of the
soil type at many locations instead of merely the 6 test holes on a
site. Therefore, the confidence limits would be greatly improved.
- Soil maps show areas that are subject to flooding or that are too
steep for construction and layout of septic tank filter fields.
3) Limitations Soil Survey Data
Maximum use of soil survey information can be made only when there is
full understanding of the limitations inherent in obtaining the data. Some of
the limitations to its use in small wastewater flows planning are:
III-A-7
-------
All criteria used in the assignment of limitation ratings (slight,
moderate and severe) are based on assumed relationships between soil
characteristics and performance of standard septic tank systems.
Local verification of these relationships is seldom obtained.
Allowance is not made in the ratings for system designs that overcome
adverse soil characteristics.
Some early soil surveys were completed prior to the present knowledge
of soils and do not reflect current concepts and interpretations.
Soil interpretations for non-agricultural uses, including septic tank
drainfields, have been included in soil surveys only within the past
two decades.
• Due to scale limitations, areas of 2 to 3 acres are seldom represented
on a detailed soils map and are instead described as inclusions in
soil mapping units.
• Soil mapping standards require that 85% of a soil area must represent
the range of properties defined by a soil name. Therefore, 15% of an
area within a soil boundary may contain slightly different soils from
the main body. However, the accuracy of the soil map units is com-
monly much less than 85%, and may average only 55% in glacial land-
scapes throughout the midwest (Rogoff, 1979).
• Boundaries between soil types are seldom absolute in nature. Instead,
soils are a continuum on the landscape (see Figure III-A-2). This is
important when delineating areas suitable for septic tank drainfields.
Figure III-A-2. Typical soil boundaries
and variations in soil
boundaries.
HOUSE
DbB
^POSSIBLE VARIATION
IN SOIL BOUNDARY
MbB2
IaB2
III-A-8
-------
• Permeability data included or soil surveys are often based upon
laboratory (column) analysis rather than field analysis (Bouma, 1974).
Permeability rates so derived do not reflect the significant varia-
tions in groundwater movement known to occur in subsurface state.
• The 3-classification system of rating soils for subsurface absorption
system suitability, as described above, focuses on the limitations
rather than the potential of the soils in question. This is a marked
disadvantage in the face of cost-effective small waste flows tech-
nologies available to overcome soil limitations.
• The single most limiting soil characteristic causes the soil to be
placed in the most limited class.
• Soil interpretations included within soil surveys do not address when
on-site systems fail. Therefore, the soil survey is not intended for
use in resolving on-site system problems.
• The soil survey accepts the soil characteristics involving a seasonal
high water table or slow percolation rates as limitations. Inexperi-
enced users of the soil survey may accept the limitation as an insur-
mountable problem.
4) Summary
Soil surveys provide valuable land resource information at a scale of 2
to 3 acres or larger. They are particularly useful in making preliminary
estimates of new use feasibility and planning site specific field work.
However, in regard to making technology selections and sewering decisions, the
cumulative effects of the listed disadvantages can often result in the rejec-
tion of techniques for wastewater treatment that are feasible and cost-
effective .
3. USE OF SOIL POTENTIAL CONCEPT IN RURAL WASTEWATER FACILITIES
PLANNING
In the early 1970's, it became clear to preparers and users of soil
surveys that the employment of soil limitation ratings was an incomplete
approach to predicting the behavior of on-site wastewater disposal systems
(McCormack, 1974). The growing use of innovative and alternative small waste
flows technologies, and increasingly available data on performance and cost of
potential practices for overcoming soils limitations in specific soil types
prompted development of the "soils potential concept." This concept takes a
positive approach to soils interpretation by focusing on the quality of a soil
after measures to correct limitations as related to other soils in an area
have been applied. Innovative technologies employed to cope with high sea-
sonal water tables and slow percolation rates can significantly increase the
amount of land suitable for on-site sewage disposal (Rogoff, 1979).
The critical elements in the soils potential approach to small waste
flows planning include the identification and recording of those practices
which successfully overcome limitations, by soil type. While the soils poten-
tial concept incorporates local information about proven methods to overcome
limitations, it does not eliminate the need for detailed field investigation
of potential drainfield sites.
III-A-9
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a. Soil Potential Ratings
Soil potential ratings are a form of soil interpretations which can
assist wastewater management planners in their determination of the relative
suitability of soils for on-site sewage treatment and disposal by (USDA, SCS
1978).
• Providing a common set of terms, applicable to all kinds of land use,
for rating the quality of a soil for a particular use relative to
other soils in the area.
• Identifying the corrective measures needed to overcome soil limita-
tions and the degree to which the measures are feasible and effective.
• Enabling local preparation of soil interpretations, using local
criteria to meet local needs.
• Providing information about soils that emphasizes feasibility of use
rather than avoidance of problems.
• Assembling in one place information on soils, corrective measures, and
the relative costs of corrective measures.
• Making soil surveys and related information more applicable and easily
used in resource planning.
• Strengthening the resource planning effort through more effective
communication of the information provided by soil surveys and properly
relating that information to modern technologies.
Soil potential ratings are intended to be used in conjunction with other
resource data (i.e., soil surveys) as a guide to making planning decisions.
Application of soil potential ratings to general decision-making is not pos-
sible without previous identification of soil type. The soil potential rating
or index for a particular soil is based on soil performance, cost of correc-
tive measures, and costs related to continuing limitations. The soils poten-
tial index (SPI) is expressed as follows (USDA, SCS, 1978):
SPI = P - (CM + CL)
where
P = Index of performance or yield as a locally established
standard.
CM = Index of costs of corrective measures to overcome or minimize
the effects of soil limitations.
CL = Index of costs resulting from continuing limitations.
The definition of soil potential classes, which range from very high to
very low, and the general concept of the SPI and procedures for preparing soil
potential ratings are presented in Appendix A.
III-A-10
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1) Limitations of Soil Potential Ratings
Although the soils potential concept represents a positive approach to
wastewater management planning, several limitations to its use must be noted:
• Soil potential ratings are to be used with caution, as they are based
on soil survey mapping. All the limitations due to scale and to soil
variations within mapping units (see Section 2) are therefore extended
into limitations in soils interpretation via potential ratings. These
ratings do not reflect location, market trends, or social and poli-
tical forces (Rogoff, 1979).
• Elements of the soil potential concept, including soil potential
ratings, typical corrective measures, and typical continuing limita-
tions are to be used only in general wastewater management planning
and are not to be applied on a specific lot without on-site investi-
gation for design and construction of the drainfield system (USDA, SCS
Champaign Co., IL, 1979).
• Soil potential ratings are not interchangeable among counties. Appli-
cation of ratings from one county to another must be preceded by field
testing.
• Corrective measures to overcome soil limitations, and their attendant
costs may become outdated quickly in light of a fast-paced state-of-
the-art in small waste flows technology. Consequently, soils poten-
tial ratings must be updated to reflect increasing labor and material
costs (Rogoff, 1979).
• Limitations within the soils potential context are viewed as problems,
though to a lesser extent than within the soil survey.
• Soil potential ratings do not address why septic tank drainfields
fail. Knowledge of problem causes is critical to the resolution of
such problems.
• Soil potential ratings are more suited to interpreting soil suita-
bility for future on-site systems than for existing systems. It is
much more straight forward and conclusive to measure performance of
existing systems directly.
• Soil potential studies are few in number. Available studies are not
used extensively by sanitarians in the permitting of new or modifi-
cation of existing systems.
2) Soils Potential Studies In Region V
A survey of the literature and of soil scientists throughout the mid-
western U.S. indicates that while there is great interest in the soil poten-
tial concept as related to on-site sewage disposal, few soil potential studies
have been completed in Region V. However, several soil potential initiatives
within the region are scheduled for completion in the early 1980's.
III-A-11
-------
Eaton County, Michigan
In his dissertation entitled A Computer Assisted Approach for Preparing
Soil Potential for Urban Land Use Management, Rogoff (1979) developed a sys-
tematic procedure to numerically rate soil potential for five urban land uses,
including septic tank drainfields in Windsor Township, Eaton County, Michigan.
Soil limitations for septic tank system usage, as noted by the Eaton County
soil survey, included slowly permeable soils, shallow depth to bedrock, and
seasonal high water tables. Results of Rogoff's study indicated that of the
12,810 acres of land in Windsor Township that are rated as having severe
limitations for on-site sewage disposal, over 11% or 2,857 acres may have good
or fair soil potential, assuming the modification of conventional septic tank
systems and construction of mound systems. This 2,857 acres represents a
potential increase of 32% in the amount of land that is suitable for on-site
wastewater disposal (Rogoff, 1979). On-site investigation of soil suitability
will determine the actual amount of additional land that is available for
development via decentralized systems.
Champaign County, Illinois
Soil potential ratings for septic tank absorption fields in Champaign
County, Illinois were completed in 1979 by the USDA Soil Conservation Service.
Evaluation factors by soil type that were considered in the preparation of
soil potential indexes are listed below along with "standard" values1 for
these factors in Champaign County (USDA, SCS, 1979):
Evaluation Factor Standard
Flooding potential None
Depth to seasonal high water table >_ 48 inches
Percolation rate; (Permeability rate) 20 rain./in. in upper
36 in. of soil;
(0.6-2.0 in/hr)
Slope >5%
The "standard" was also assumed in this study to include a three-bedroom
residence with a private water supply, a 1,000 gallon septic tank with dis-
tribution box, and 750 square feet of drainfield.
Soil potential ratings for on-site systems were developed as a guide to
land use planning only in Champaign County and were based on a consideration
of 1) soil performance levels, 2) the difficulty or relative cost of correc-
tive measures that would improve soil performance, and 3) any adverse environ-
mental, economic and social impacts of soil limitations that cannot be
feasibly overcome.
Soil potential ratings, in accounting for soil performance levels with
respect to conventional septic tank systems in Champaign County, have been
used successfully in the development of rehabilitative measures for existing
^"Standard" values for evaluation factors are associated with those soils have
"slight" limitations for on-site sewage disposal.
III-A-12
-------
systems that have failed (by telephone, Wyley Scott, USDA, SCS, Champaign
County, IL, 2 Feb 81). Recommended corrective measures include the employment
of aeration systems, mound systems, buried sand filters, and pressurized dis-
tribution systems. The amount of additional acreage that may be suitable for
on-site sewage disposal as a result of modified conventional system and
installation of alternative technologies has never been quantified, but it is
likely to be significant in light of the excessive amount of system malfunc-
tions and severely limited soils inventoried in the draft Champaign County
soil survey (by telephone, Wells Andrews, USDA, SCS, Champaign Co. IL, 19 Dec
80; Wyley Scott, 2 Feb. 81).
It is noted that local sanitarians and geologists from the Illinois State
Geological Survey involved in the Champaign County Study concluded that low
density septic tank systems in sand and gravel soils do not cause pollution of
groundwater resources (USDA, SCS, 1979). However, regular testing of wells in
these soils should be conducted as a precautionary measure. This recommenda-
tion underscores the importance of field investigation as follow-up to general
soil potential classifications.
Northeastern Illinois
Work on developing soil potential ratings for on-site sewage disposal has
begun in the six-county area surrounding Chicago including Lake, McHenry,
Kane, Cook, DuPage, and Will Counties. Efforts to date have consisted of
meetings among multidisciplinary technical professional to organize the study.
The format of the six-county soil potential report will be identical to that
of Champaign County, Illinois (by telephone, Earl Voss, USDA SCS, Champaign
Co. IL, 19 Dec 80).
State of Indiana
Small waste flows specialists in the On-Site Waste Disposal Program at
Purdue University's Agronomy Department have undertaken a soil potential study
in the Great Lakes Watershed of Indiana. A computerized approach is being
developed so that soil potential information produced for counties in this
watershed may be extended to other counties in Indiana. In addition, the
On-Site Waste Disposal Program in concert with other midwestern states, will
examine alternative ways of rating soils for septic tank systems (by
telephone, Dr. Joseph Yahner, Purdue University, 2 Feb 81).
The objective of these studies is to compare field observed soil absorp-
tion system performance with system performance predicted in soil surveys.
The degree of data correlation will be determined through field testing and
laboratory analysis. Results of these studies have the potential to modify
existing state regulations2 regarding septic system construction in soils with
"severe" limitations (by telephone, Stephen Hudkins, Purdue University, 23 Dec
80).
2Current state regulations prohibit the construction of septic tank systems on
soils with "severe" ratings for such use as determined by soil surveys. It is
estimated that over 70% of Indiana's soils have severe limitations or are
unsuited for conventional septic tank-soil absorption systems. Unsuitable
soil conditions include seasonal high water tables, slow soil permeability and
slope by letter Stephen Hudkins, Purdue University to Alfred Krause, USEPA
Region V, 25 June 1979).
III-A-13
-------
3) Summary
The soil potential concept refines the wastewater management planning
process, but like the soil survey, does not provide site-specific data that
are essential to detailed decision-making. Particularly important among these
data is information relevant to the causes of on-site system malfunctions.
However, the main advantage of soil potential ratings is their recognition
that some limitations can be overcome. Methods and costs of overcoming limi-
tations are integral to the rating.
4. USE OF EMPIRICAL SOILS DATA IN RURAL WASTEWATER FACILITIES
PLANNING
Many on-site sewage disposal systems installed in soils known to have
severe limitations have continually served the wastewater management needs of
rural communities without occurrence of system malfunction. The extent to
which this apparent paradox exists today underscores the importance of incor-
porating site-specific soil data and empirical on-site system performance
data, collectively termed "empirical soils data", into the wastewater manage-
ment decision-making process. This phenomenon! becomes less paradoxical when
it is understood that the assignment of "severe" limitation to these soils was
based upon an assumed or hypothetical relationship between soil characteris-
tics and on-site system performance. Predictions of soil suitability for
on-site sewage disposal based upon hypothetical relationships are appropriate
for planning-level decisions relevant to existing and future systems. How-
ever, decisions regarding site-specific technology selection and system design
must be based upon locally verified relationships between soil characteristics
and on-site system performance. These decisions are possible through use of
empirical soils data.
The gathering, assessment, and retention of empirical soils data, prin-
cipally empirical performance data, are essential to evaluate causes of septic
system failure, and more accurately predict future system performance than is
possible through use of soil maps and soil ratings. Unlike soil surveys and
soil potential ratings, performance data will indicate whether soil charac-
teristics such as seasonal high water tables, slow percolation rates, shallow
depth to bedrock, and slope are in fact determinative for efficient operation
of on-site systems. Use of empirical soils data will enable local sanitation
officials to address why systems are working in soils that are predicted to be
unsuitable for on-site sewage disposal and, conversely, why systems are fail-
ing in soils predicted to have slight or moderate limitations for on-site
disposal. This is not to suggest that there is a solution to every problem.
Some soils may never be suitable for on-site systems despite attempts to apply
alternative and innovative technologies to overcome site-specific limitations.
The suggestion is made, however, that the use of empirical soils data has not
been optimized in the past. Opportunity costs incurred by rural unsewered
communities which have not made use of available empirical soils data are high
in the face of increasingly costly centralized sewerage or other off-site
facilities which may be proposed to meet their wastewater management needs.
The Illinois Environmental Protection Agency (1977) has noted the impor-
tance of performance data in its "Guidelines for the Preparation of Facilities
Plans for Unsewered Communities":
III-A-14
-------
"In general, the actual performance of properly designed and
installed septic systems should be regarded as a more meaningful
indicator of the soil's ability or lack of ability to support
absorption systems than permeability or percolation ratings for the
area."
It must not be inferred from this quote that soil permeability data are
irrelevant to the wastewater management process. As previously discussed,
these and other data including depth to bedrock and seasonal high groundwater
help define the scope and resource requirements of efforts to locally verify
the relationship between soil characteristics and the performance of septic
tank systems. However, soil characteristics data by themselves do not accu-
rately explain the performance of existing systems or predict the performance
of future systems. Explanative or predictive accuracy is best achieved
through correlation of these data with existing system performance informa-
tion.
Historically, the costs of securing empirical data have been regarded as
prohibitive by small rural communities. Additionally, soils scientists and
sanitarians believe that the collection, assessment and retention of empirical
soils data for future decision-making are resource intensive efforts better
left to the "research and development" community. Officials cite time and
personnel restraints and total commitments to "putting out fires" as impedi-
ments to actively developing an empirical soils data base.
In actuality, these data are collected continually by sanitarians and
soil scientists during site-specific investigations of on-site system feasi-
bility and system performance. Therefore, costs associated with obtaining
this information are low. Assessment and tabulation of available soils and
performance data for inclusion in an empirical data base could be performed
during the winter months when field investigation efforts, and therefore, time
and personnel constraints, are minimal.3 The empirical data base should be
developed in a way that will facilitate statistical correlation of soil
characteristics, other determinants of performance and on-site system perfor-
mance itself for use by local, regional, and state governments in Region V.
The economic justification for the collection and use of empirical soils
data should be based on 1) a moderate to high level of community interest in
on-site systems and 2) the fact that cost savings from optimum operation of
existing systems far outweigh the costs associated with data collection. The
optimum operation approach is based upon the collection and use of empirical
information. It is frequently more cost-effective than construction of new
centralized facilities which do not require this information.
The use of empirical soils data in detailed wastewater management plan-
ning (i.e. decision-making) in no way precludes the need to conduct on-site
investigations prior to system design. The planning application of empirical
soils data will determine if apparently limiting soil characteristics indeed
inhibit effective on-site sewage treatment. By extension, these data will
suggest what technologies may be appropriate to correct observed limitations
and improve performance. However, they do not determine system sizing and
cost, both which must be ascertained following careful investigation of indi-
vidual lots.
It is noted, however, that for quick turn-around, community-wide assessments
of on-site system performance, as described in Section II.I, additional per-
sonnel may be needed.
III-A-15
-------
a. Empirical Approach
The suggested approach to collecting, assessing, and using empirical
soils data in small waste flows planning and management involves six stages:
1. Detection of individual malfunctions
2. Collection of data relevant to the causes of malfunctions
3. Assessment of likely causal relationships between data collected and
malfunctions
4. Use of causally defined relationships in decision-making for mal-
functioning systems
5. Use of causally defined relationships in decision-making for systems
similiar to those that are malfunctioning
6. Development of regional or state data bases for increasing knowledge
of on-site system capabilities and proven limitations.
Each of these steps is briefly described below.
Stage 1: Detection of Individual Malfunctions
The empirical approach begins with the detection of obvious problems
associated with on-site system performance. These problems are manifested by:
• surface malfunctions (effluent rising to the surface)
• groundwater malfunctions (insufficient removal of wastewater con-
stituents by the soil)
• back-up malfunction (sewage backing up in the system).
Methods that may be used to obtain direct evidence of the type and extent
of individual malfunctions include (USEPA: "Region V Guidance," 1981):
• Direct observation
• Mailed questionnaires
• Survey of local sanitarians, zoning officials, or septage haulers
• Aerial photography/field investigation (surface malfunctions)
• Well inspection, and sampling and analyis of groundwater for
whiteners, chlorides, nitrates, fecal coliform bacteria or other
indicators
III-A-16
-------
• Analysis of samples taken from septic tank effluents entering surface
water bodies through soil.
During preparation of the Seven Rural Lake EISs, U.S. EPA used the fol-
lowing methods to detect individual on-site system problems:
• Remote sensing by aerial photographs was conducted by U.S. EPA's
Environmental Photographic Interpretation Center (EPIC) to detect
septic system failures noticeable at the soil surface. True color and
color infrared film was used in the aerial survey.
Suspected surface malfunctions detected during inspection of the aerial
photographs were subsequently field-checked and recorded. Very heavy tree
cover can limit the effectiveness of this method (Krause, et. al. 1979).
Locations of the 42 confirmed4 and 57 marginal5 surface malfunctions
detected by EPIC personnel in Salem Utility District No. 2, Kenosha County,
Wisconsin are shown in Figure III-A-3. The combined number of system failures
that were noticeable at the soil surface represented approximately 5% of the
total on-site systems in the District.
• Septic leachate surveys were conducted along lake shorelines to detect
the emergence of groundwater plumes from nearby septic tank drain-
fields. Detection of organic and inorganic chemicals associated with
domestic wastewater, coliform bacteria, and elevated nutrient concen-
trations signaled the failure of septic tank systems beneath the soil
surface. Such failures normally occur when the soil used in the
drainfield has a percolation rate that is too rapid for effective
renovation of wastewater and groundwater flows toward a lake shore-
line.
• Sanitary survey of a representative number of residences to visually
inspect lots and discuss home sewage disposal problems with residents,
including sewage back-ups.
Stage 2; Collection of Data Relevant to Causes of Malfunctions
The empirical approach recognizes that several major factors such as
permeability and depth to groundwater, in addition to soil characteristics,
affect the performance of on-site systems. These factors include:
• System design
• System age
• System usage
• System maintenance
Malfunctionswere"confirmed" if standing wastewater or seepage from septic
tanks was visible on the land surface during field inspection.
Malfunctions were "marginal" if the accumulation of excess organic matter or
the presence of dead vegetation indicated that septic tank systems had con-
firmed malfunctions in the past.
III-A-17
-------
• Physical condition of structural system components (tanks, distri-
bution boxes, pipes, etc.)
• Biological condition of drainfield (clogging and soil aeration)
• Surface drainage
• Groundwater hydrology
Collection of information relevant to these factors therefore constitutes a
logical step in the small waste flows decision-making process during which
anomalous system performance should be evaluated on a representative basis.
Data on system design, age, usage, maintenance, and condition can be secured
during partial sanitary surveys involving interviews with residents and
inspection of properties.
In addition, information on local soil characteristics including texture,
horizonation, depth, slope, and water table elevation should be obtained in
this step for assessment in Stage 3. These data may be available from soil
surveys, soil scientists, well drillers and local contractors, or may be
obtained during representative sampling of developed properties.
Collection of data relevant to causes of on-site system malfunctions is
briefly described in Section IV.C.2 of U.S. EPA's Region V Guidance: Site
Specific Needs Determination and Alternative Planning for Unsewered Areas.
Stage 3; Assessing Likely Causal Relationships Between Data
Collected and System Malfunctions
This stage involves an assessment of the data gathered in Stages 1 and 2.
It specifically seeks to address why existing on-site system malfunctions
occur. Results of Stage 3 will determine the nature of repair, replacement,
and maintenance techniques required for malfunctioning systems in Stage 4, and
for similiar but not yet failing systems in Stage 5. It is emphasized that
efforts undertaken during Stage 3 serve to verify relationships between soil
characteristics and on-site system performance. These relationships are
essential to the small waste flows decision-making process.
An assessment of the likely causal relationships between data relevant to
on-site system malfunctions and malfunctions themselves was undertaken by U.S.
EPA during its preparation of seven EISs referenced earlier. Salem Utility
District No. 2, Kenosha County, Wisconsin is used again as an example of how
this assessment could be made.
The location of surface malfunctions in the District detected by aerial
photography and subsequent field-checking is illustrated in Figure III-A-3.
An initial assessment of the cause of these malfunctions may be performed by
correlating information contained in Figure III-A-3 with three limiting soil
conditions identified in the District based upon the Soil Survey for Kenosha
and Racine Counties (Link and Demo, 1970):
1. Permeability less than 0.63 in/hr (permeability problems)
III-A-18
-------
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III-A-19
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2. Depth to seasonal high groundwater less than 3 ft. (groundwater
problems)
3. 1 and 2 combined
Figure III-A-4 illustrates this correlation, focusing on the most densely
populated area in the District. It is an example of how causal relationships
between available soils data and identified on-site system malfunctions can
begin to be made. Most confirmed malfunctions in the vicinity of Center Lake,
Camp Lake and Rock Lake are indicated in Figure III-A-4 to be associated with
poorly drained soils, having permeability rates less than 0.63 inches/hour.
Marginal malfunctions are indicated to be associated with both high ground-
water levels and slow permeability rates. It is emphasized that correlations
between available soil and malfunction data as illustrated in Figure III-A-4
are only first order assessments of problems and their causes. Additional
information about on-site system design, age, usage, maintenance and condi-
tion, obtained during a sanitary survey, and detailed malfunction analysis
(See Section II.I) is required by local officials before appropriate small
waste flows technologies and management techniques may be selected to overcome
existing and future problems.
The correlation between malfunction data (Figure III-A-3) and soil limi-
tation ratings (slight, moderate and severe) illustrated in Figure III-A-4
does not define this causal relationship. In the absence of data suggesting
the causes of septic tank system failure, the small waste flows specialist is
unable to efficiently provide technological and management responses to waste-
water management problems during the decision-making process.
Stage 4: Use of Causally Defined Relationships in Decision-
Making for Malfunctioning Qn-Site Systems.
As previously indicated, locally verified relationships between on-site
system performance and limiting soil characteristics are essential to the
repair, replacement, and maintenance of existing systems that have failed.
These relations, developed during Stages 1 through 3, can be used at varying
phases of the small wasteflows decision-making process, including:
1. Estimation of the numbers and types or replace malfunctioning of
appropriate technologies to upgrade on-site systems with an entire
community (Note: this does not involve technology selection).
2. Design of site analyses conducted to further investigate causal
relationships.
3. Selection of site-specific technologies to overcome on-site system
problems.
The data presented in Table III-A-4 illustrates how the first decision-
making phase was accomplished for the Salem case. Table III-A-4 correlates
surface malfunctions (confirmed and marginal) and other on-site system
problems with soil series and their attendant characteristics relevant to
groundwater conditions and permeability. It also suggests technological
responses to apparent, yet not fully defined problems. These "suggested
responses" will be modified or verified once Phases 2 and 3 above are com-
pleted.
III-A-20
-------
NO PERMEABILITY OR GROUNDWATER LIMITATIONS
PERMEABILITY LESS THAN 0.63 IN./HR.
DEPTH TO SEASONAL HIGH WATER TABLE LESS
THAN 3 FEET
PERMEABILITY LESS THAN 0.63 IN./HR. AND
DEPTH TO SEASONAL HIGH WATER TABLE LESS
THAN 3 FEET
^£"10 GRAVEL, CLAY PITS AND PONDS
• CONFIRMED SEPTIC TANK MALFUNCTIONS
O MARGINALLY FAILING SEPTIC TANKS
Figure III-A-4.
Detailed correlation of available
soil and malfunction data for
Salem Utility District No. 2,
Kenosha County, Wisconsin
Source: Link and Demo, 1970; U.S. EPA-EPIC, 1979
III-A-21
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III-A-22
-------
Stage 5; Use of Causally Defined Relationships in Decision-
Making for Similar Systems
Use of locally verified causal relationships between performance and
factors influencing performance is not restricted to existing on-site systems
that have failed. Their use extends to similar systems that have not yet
exhibited any problems. Information developed and standardized during Stage 4
can be extrapolated for use in this stage provided conditions relevant to
on-site system performance are similar. These conditions include soil
characteristics along with system design condition, and maintenance.
Stage 6; Development of Regional or State Data Bases for
Increasing Knowledge of On-Site System Capabilities
and proven Limitations.
The final step of the empirical approach involves the synthesis of
empirical soils and performance data developed and tabulated by local sani-
tarians and soil scientists for use by regional or state small waste flows
officials. The accumulation of empirical data by counties and municipalities
would improve knowledge of on-site system capabilities and proven limitations
held by small waste flows planners at higher levels of government who are
committed to provide cost-effective wastewater management in their jurisdic-
tions. This commitment encompasses both existing and future on-site systems.
Development of regional or state data bases, over time, could result in
modification of existing sanitation regulations which do not reflect actual
performance of on-site systems under hypothetically limiting conditions.
State regulations presently limit development on marginal but potentially
satisfactory soils on the basis of unverified relationships between on-site
system performance and soil characteristics. Computerized data bases which
correlate soil characteristics and on-site system performance could improve
design and permitting decisions. Until a substantial data base is estab-
lished, however, the present criteria are the best available for permitting
decisions relevant to new on-site systems.
Increased knowledge of on-site system capabilities and proven limitations
at the regional and state level may also precipitate the preparation of
"supplements" to conventional soil surveys addressing soil suitability for
on-site sewage disposal. These supplements could be prepared by the USDA Soil
Conservation Service in cooperation with State agricultural experiment
stations but would incorporate empirical performance data secured by local
sanitarians and soil scientists. Supplementary information would not super-
cede information contained in the soil survey but would help rural area resi-
dents install operational and economical on-site systems through inclusion of
the following data (by telephone, Lloyd Wright, USDA Soil Conservation
Service, Washington, D.C., 22 Dec 80):
• Performance history of systems in use by soil type
• Regulations pertaining to construction and maintenance of systems
• Correlation of soil limitations and performance, addressing why
systems are working and why they are failing
III-A-23
-------
• Local techniques which successfully overcome soil limitations.
b. Summary
The empirical approach recognizes that actual on-site system performance
is influenced not only by local soil characteristics but also by system
design, construction, condition, use and maintenance. It further recognizes
that small waste flows decision-making, as opposed to large-scale planning,
must be based upon locally verified, not hypothetical relationships between
performance and performance "factors." Use of empirical soils data is
feasible, conclusive, and cost-effective for small waste flows planning and
site-specific technology selection. As with the soil survey and soil poten-
tial approaches, the use of empirical soils data does not eliminate the need
for on-site investigation prior to site-specific system design and costing.
Indeed, its use is based almost entirely on on-site investigation.
III-A-24
-------
REFERENCES
SCS-USDA, 1975. Soils and septic tanks. Agriculture Information Bulletin
349.
Parker, Dole E. 1977. Soil evaluation of sites for absorption systems in
individual on-Site wastewater systems.
Illinois Environmental Protection Agency. Guidelines for the preparation of
facilities plans for unsewered communities.
Wisconsin Department of Health and Social Services. 1979. Soil tester
manual. Division of Health, Bureau of Environmental Health.
U.S. Environmental Protection Agency. 1980. On-site wastewater treatment and
disposal systems design manual.
Goldstein, S. N. and W. J. Molberg. 1973. Wastewater treatment systems for
rural communities.
Indiana Heartland Coordinating Commission. 1979. Hendricks County sewage
treatment management study.
Bouma, J. 1974. New concepts in soil survey interpretations for on-site
disposal of septic tank effluent. Soil Science Society of America
Proceedings 28:941-946.
Rogoff, Marc J. 1979. A computer-assisted approach for preparing ratings of
soil potential for urban land use management. Ph.D. dissertation,
Michigan State University.
Clayton, John W. 1975. An analysis of septic tank survival data from 1952 to
1972 in Fairfax County, Virginia. In: Water pollution control in low
density areas. Proceedings of a rural environmental engineering con-
ference, pp. 75-87.
Virginia Polytechnic Institute and State University Extension Division. 1977.
Layman's guide to evaluating soil potential for a septic tank drainfield.
Publication 750.
Mellen, William. 1975. Recommendations for soil potentials (excerpt).
Olson, Gerald W., 1966. Improving soil survey interpretations through
research. In: Soil surveys and land use planning, by L. J. Bartelli, et
al. Soil Science Society of America and American Society of Agronomy.
Davis, Joel D. 1979. An assessment of the on-Site wastewater management
program in Maine. University of Maine, Orono ME.
U.S. Environmental Protection Agency. 1980. Planning wastewater management
facilities for small communities. EPA-600/8-80-030.
III-A-25
-------
Olson, Gerald W. 1964. Application of soil survey to problems of health,
sanitation, and engineering. Memoir 387. Cornell University, Ithaca NY
McCormack, Donald E. 1974. Soil potentials: A positive approach to urban
planning. J. of Soil and Water Conservation 29(6):258-262.
American Society of Agricultural Engineers. 1978. Home sewage treatment:
Proceedings of the Second National Home Sewage Treatment Symposium, 12-13
December 1977.
USDA Soil Conservation Service. 1978. List of published soil surveys.
USDA Soil Conservation Service. 1978. National soil handbook.
Gannon, John E., and Arthur Gold. 1979. The suitability of soils for on-site
wastewater disposal (Part II). In: Limnological features of Crooked and
Pickerel Lakes, Emmet County, Michigan. Technical Report No. 8.
University of Michigan Biological Station.
Wisconsin Department of Natural Resources and Wisconsin Department of Health
and Social Services. 1978. The failing septic system. In: Upstream-
downstream.
Johnson, William M., and Linck J. Bartelli. 1974. Rural Development:
Natural resource dimensions. J. of Soil and Water Conservation 29(1).
III-A-26
-------
APPENDIX A
The following are definitions of each of the soil potential classes as
defined in Rogoff 1979.
Excellent Soil Potential—Soils rated excellent have properties excep-
tionally favorable for the intended use. Soil limitations or restric-
tions are minor and can be corrected with usual management techniques or
practices to assure high performance for the intended use. The initial
installation and management costs to establish the use or maintain it are
inexpensive compared to those on all other soils in the county. Continu-
ing limitations are slight after these corrective measures have been
applied. Soils rated excellent are the best in the county for the
intended use.
Good Soil Potential—Soils rated good have properties favorable for the
intended use. Some soil limitations or restrictions exist, but measures
necessary to overcome these limitations are available. The measures
needed usually increase costs of establishing or maintaining the use, but
are not generally prohibitive in relation to design costs for soils rated
fair or poor. Limitations continuing after these corrective measures are
installed are slight. Performance for the intended use can be expected
to be good.
Fair Soil Potential—Soils rated fair have many properties favorable for
the intended use. One or more soil limitations exist that can be over-
come with corrective measures, but limitations are primarily of a con-
tinuing nature requiring practices or designs that need to be maintained,
or are more difficult, unusual, and costly. Limitations continuing after
these corrective measures have been applied are commonly moderate.
Performance for the intended use can be expected to be fair.
Poor Soil Potential—Soils rated poor have properties unfavorable for the
intended use. One or more soil limitations exist that are extremely
difficult to overcome. The initial installation or maintenance cost of
these measures, if available, are prohibitive as compared to those needed
on all other soils in the country. Limitations continuing after these
corrective measures are installed are severe and seriously detract from
environmental quality or economic returns. Performance for the intended
use can be expected to be poor. Soils rated poor are the worst in the
county for the intended use.
III-A-27
-------
B. PICKEREL LAKE, MICHIGAN, CLUSTER SYSTEM SITE ANALYSIS
Evaluations of needs for improved wastewater facilities were conducted
around Pickerel Lake and along the south shore of Crooked Lake in Emmet
County, Michigan during 1978. (U.S. EPA, 1980). In addition to scattered
individual problems, two housing clusters on the south shore of Pickerel Lake,
Ellsworth Point and Botsford Landing, were identified as possibly requiring
some form of treatment off-site. Because of the proximity of soils that,
based on county soils map information, are potentially suitable for multi-
family soil absorption systems, cluster systems were proposed, subject to more
thorough investigation of needs and to hydrogeologic testing of potential
disposal sites.
Site selection and hydrogeologic testing of the disposal sites were
performed to demonstrate appropriate techniques.
1. SITE SELECTION
Preliminary screening of potential cluster system sites was accomplished
by evaluating the soils and geologic information previously gathered (Alfred
et al., 1973). Additional information was gathered through a site visit and
discussions with landowners concerning their knowledge of the soil on their
property gained through water well drilling, septic tank installation, and
personal investigation.
Sites for the proposed cluster systems were selected based on probability
of thickness of unsaturated sands, ease of access (no trees), and cooperation
from the landowners. The site locations are shown in Figure III-B-1. For the
Botsford Landing area, the landowner whose property had the greatest potential
based on all three criteria was Charles Kreeger, owner of Camp Petosega. Soil
borings had been conducted on his property previously for an engineering
design of a cluster drainfield for the camp. The area of investigation was to
the west of where the area of interest currently lies. Two borings to 20 feet
had encountered fine to medium sands throughout and no water table. These
factors indicated that the Kreeger property would be ideal for a cluster
drainfield.
For the Ellsworth Point area, the location that appeared to have the
greatest potential for a cluster drainfield was the old beach sands on the
terrace above Artesian Lane. Three properties on the terrace were identified
as having the greatest potential--from east to west, those of Ray Johnston,
Warren Keller, and Henry Hannan. Only the Keller property was cleared; access
to the others would have been difficult and would have involved clearing.
From the soils survey and information concerning their wells and septic tank
drainfields obtained from the respective landowners, it was expected that the
clay and gravel glacial till sloped steeply from south to north under the
properties and that about 20 feet of unsaturated sands would be found near the
escarpment. This information suggested that the Keller property would be
suitable for a cluster drainfield.
WAPORA, Inc. subcontracted Geo-Tek, Inc., of Lowell, Michigan, to conduct
the field testing program. This included borings and soil samples, installa-
tion of piezometers, water sampling, and restoration of the sites. WAPORA,
Inc. personnel directed the work, performed the level survey, and conducted
III-B-1
-------
S!o
\
X—EIS
STUDY
AREA
BOUNDARY
CHARLES
KREEGER
HARDWOOD
STATE FOREST
WARREN
KELLER
Figure III-B-1.
The two properties proposed for cluster drainfields
on which soil boring programs were conducted.
Emmet County, Michigan.
III-B-2
-------
the water quality tests. The field work commenced on 20 October 1980 and was
completed on 22 October 1980.
2. SOIL BORINGS
The soil borings were conducted with a CME-45 drill rig mounted on a
four-wheeled trailer. The soil borings were drilled to depths ranging from
19.5 to 50.5 feet., they were drilled by means of continuous flight, hollow-
stem auger. At each site, one boring was conducted with continuous split
spoon sampling through and below the hollow-stem auger. This allowed the
drillers to observe undisturbed cores of soil material for the drilling log.
The other borings were conducted with continuous auger boring, with observa-
tions made of the material brought to the surface for the drilers log, and by
occasional split spoon samples when changes of material were encountered.
Undisturbed samples of soil material for permeability and soil charac-
teristics tests were obtained by means of three-inch diameter Shelby tubes.
These were taken from representative soil material at various depths through
and below the hollow-stem auger. The Shelby tube ends were sealed with melted
wax for transport to the soil testing laboratory.
a. Piezometers and Water Sampling
In borings where enough groundwater was encountered to justify a piezo-
meter, a two-inch diameter well was installed through the hollow-stem auger.
The piezometer consisted of a six-foot-long slotted (0.010 inch) plastic well
screen and solvent welded Schedule 40 PVC pipe for the casing.
After each piezometer had rested for at least 24 hours, the depth from
the ground surface to the water table was measured. Then, an electrically
powered jet pump was attached to the exposed casing and the well pumped to
clear water where this was considered feasible. A water sample was then
taken, its pH and temperature measured and recorded, and the sample bottle
marked and packed for shipment to the WAPORA, Inc. water testing laboratory in
Cincinnati, Ohio. Where too small amounts of saturated sands were encountered
to justify attempts to pump the water clear, a modified bailing procedure was
employed to obtain a water sample. The relative elevation of the ground
surface at each boring was obtained with a surveyor's level. On the Kreeger
property, a temporary bench mark established by a previous survey was
utilized. On the Keller property, the ground elevation was estimated based on
USGS topographic contours.
After the water samples had been collected, the piezometers were pulled
and the holes filled with the excavated material.
b. Laboratory Soil Tests
The laboratory tests on the soils were conducted by Materials Testing
Consultants, Inc. of Grand Rapids, Michigan, for Geo-Tek, Inc. The soil
samples were tested for original moisture content, original wet density, dry
density, specific gravity, void ratio, and undisturbed vertical permeability.
These tests were conducted using standard laboratory methods for soils.
The capability of soil material to accept and conduct water determines
the maximum rate at which septic tank effluent can be applied to the drain-
field. In this study, the most important hydraulic properties were vertical
III-B-3
-------
and horizontal permeabilities. The vertical permeability of the soil samples
was determined in the laboratory by the falling-head permeameter method.
Where the soil material is nearly homogeneous, the horizontal permeability
will approach the value for vertical permeability but will almost always be
larger because horizontal layering affects vertical permeability more than
horizontal permeability. To illustrate the effect of layering on horizontal
and vertical permeabilities, the following example, using values from the
laboratory testing, is presented. The first layer is 10-feet thick and has a
permeability of 2 inches per hour, the second layer is 0.1-feet thick and has
a permeability of 0.02 inch per hour, and the third layer is 10-feet thick and
has a permeability of 2 inches per hour. The vertical permeability (harmonic
mean) would be given by:
D
Kv = dl + d2 + d3
kl k2 k3
20.1 ft
= 10 ft + 0.1 ft f 10 ft
2 in/hr 0.02 in/hr 2 in/hr
Kv = 1.34 in/hr
This value is considerably less than that of the majority of the soil ma-
terial. The horizontal permeability would be given by:
„, _ dlkl + d2k2 + d3k3
Kh - g
10 ft x 2 in/hr + 0.1 ft x 0.02 in/hr + 10 ft x 2 in/hr
20.1 ft
Kh = 1.98 in/hr
Thus, overall horizontal permeability is only minimally affected by thin
layers of lesser permeability. These formulae must be considered when the
laboratory data for vertical permeability are utilized for horizontal per-
meability estimates.
c. Laboratory Water Tests
The water samples were analyzed in the WAPORA, Inc. laboratory in
Cincinnati, Ohio on 22 October 1980. The tests for total phosphorus and
nitrates were performed according to the standard procedures given in the
Standard Methods for Examination of Water and Wastewater (American Public
Health Association, 1975). Two samples could be tesced directly, while two
others had to be filtered before the laboratory tests because excessive soil
particles were present (these were from the bailer-sampled wells).
3. RESULTS AND DISCUSSION FOR EACH SITE
The field and laboratory program has provided quantitative information
about the physical and chemical characteristics of the two sites under consi-
deration as potential cluster drainfield sites. The following sections pre-
III-B-4
-------
sent detailed descriptions and discussions of each site, based on the test
results and their interpretations.
a. Charles Kreeger Property
This site (Figure III-B-2) includes the southwest corner of Camp Petosega
at the bend in Camp Petosega Road. It is located in T. 35 N. , R. 4 W. , sec.
36 and is under the political jurisdiction of Springvale Township. The land
to the south and west is owned by Eleanor Poquette. The site plan shown was
taken from a topographic plan prepared by Abrams Aerial Survey for the owner.
Presently, the area is covered with unmowed grasses and weeds, typical of
infertile sands that have a low water-holding capacity. The quality of the
grasses improves noticeably toward the south property boundary. A strip of
trees, about 80-feet wide, borders the south property boundary. A mowed
softball diamond is located in the southwest corner of the property. Also
shown on the site plan are the rough boundaries of the airfield that was used
until about 1974 by the former owner. (Its use may be restored again.) A
high-pressure gas pipeline bisects the property as shown. Northwest of boring
1 is an active borrow area where sand has been removed for construction
activities in Camp Petosega.
This site is characterized by nearly level topography and sandy soils.
The surface soil material consists of old lake beach overlying morainal ma-
terial. The topography and soil mapping indicate that the morainal material
slopes from south to north in the general area. This is also borne out by the
soil borings and well logs from the area. The old lake beach was probably
eroded along the bottom of the escarpment that lies to the north of borings 1
and 2. The sands exposed within the borrow area exhibit the variable deposi-
tion angles characteristic of beaches and dunes.
The soil boring logs prepared from observations by WAPORA, Inc. personnel
are presented in Figures III-B-3, III-B-4, and III-B-5. The driller's logs
are included in Appendix A. The two borings on the north, borings 1 and 2,
show that medium and fine sands dominate to a depth of about 25 feet, below
which some thin lenses of silty sand are present to a depth of about 40 feet
(Figure III-B-6). The boring to the south, boring 3, shows that the lenses of
silty sands are encountered at a depth of only 7 feet and that clayey material
is encountered at a depth of 24 feet. Thus, the borings show that permeable
material is much thicker near the escarpment, and that the logical location
for the drainfield would be near the escarpment.
Water table measurements are also shown on the soil boring logs (Figures
III-B-3, III-B-4, and III-B-5). The water table drops approximately 9 feet
between boring 3 and borings 1 and 2 (Figure III-B-6). This strong slope
reflects the presence of an aquitard that falls off in the direction of
Pickerel Lake. The groundwater flow direction would be toward the lake, in a
north-northwesterly direction. The owner reports that below the escarpment
the groundwater depth is approximately 3 feet or an elevation of 606 above
mean sea level (MSL). The water elevation in Cedar Creek, about 1300
feet north of boring 1, is about 595 MSL. Pickerel Lake, about 1300 feet
northwest of boring 1, has an elevation of about 593 MSL. Because the ground-
water flow from the south becomes concentrated toward the lake, the slope of
the water table surface and the flow of groundwater is probably in the direc-
tion of the lake and not north toward Cedar Creek.
III-B-5
-------
3
CHARLES KREEGER PROPERTY
ABRAMS AERIAL SURVEY PRE-
PARED FOR CHARLES KREEGER.
£} $ ppo POWER POLE
-------
Figure III-B-3. Soil boring 1, Charles Kreeger property, performed
by Geo-Tek, Inc., on October 20, 1980. Logged by
continuous split spoon sampling.
FEET
Q ELEV. 632.3
REDDISH BROWN, GRADING TO BROWN, MEDIUM SAND
2.2-
5~
10-
15-H
16.0-
17.5-
LIGHT BROWN MEDIUM TO FINE SAND
LIGHT BROWN FINE SAND
MEDIUM TO FINE SAND
LIGHT BROWN VERY FINE SAND AND SILT, WET
SHELBY TUBE
•STATIC WATER LEVEL 608.9
30-
35-H
36.5
38.0
40-11
LIGHT BROWN FINE TO MEDIUM SAND, SATURATED
1
LIGHT BROWN FINE TO VERY FINE SAND, SOME SILT
• REDDISH BROWN MEDIUM SAND
LIGHT BROWN VERY FINE SAND
•
LIGHT BROWN MEDIUM TO FINE SAND
CONTINUED
III-B-7
-------
Figure III-B-3. (continued)
FEET
40-n
41.0-
43.0-
45-
47.0-
49.0-
50-
50.5'
CONTINUED
LIGHT BROWN MEDIUM TO FINE SAND
M
LIGHT BROWN VERY FINE SAND WITH SOME SILT
LIGHT BROWN MEDIUM TO FINE SAND
LIGHT BROWNISH GRAY SILTY FINE SAND
M
LIGHT GRAY CLAYEY SILT
"EOB
III-B-8
-------
Figure III-B-4.
Soil boring 2, Charles Kreeger property, performed
by Geo-Tek, Inc., on October 20, 1980. Logged by
auger cuttings.
FEET
Q ELEV. 634.4
5-
REDDISH BROWN TO BROWN, MEDIUM SAND
SILTY SAND, SLIGHTLY PLASTIC
10-
15-
25-i
26.5
30H
35-
40-i-EOB
LIGHT BROWN MEDIUM TO FINE SAND
•STATIC WATER LEVEL 609.3
LIGHT BROWN MEDIUM TO FINE SAND WITH OCCASIONAL LENSES
OF SILTY FINE SAND
-------
Figure III-B-5.
Soil boring 3, Charles Kreeger property, performed
by Geo-Tek, Inc., on October 20-21, 1980. Logged
by auger cuttings and periodic split spoon samples.
(Two adjacent borings logged as one.)
FEET
O-i
1.0-
4.0'
5H
ELEV. 6337
DARK BROWN SANDY LOAM TOPSOIL
BROWN MEDIUM SAND
LIGHT BROWN MEDIUM TO FINE SAND
ILIGHT BROWN SILTY SAND
I SHELBY TUBE
10-V^LIGHT BROWN SILTY SAND
ILIGHT BROWN SILTY SAND
|5_f»LIGHT BROWN VERY FINE SAND STATIC WATER LEVEL 618.7
19.0
20
1
24.0-
25-
30-
BUFF FINE TO VERY FINE SAND
BUFF SANDY CLAY, WITH OCCASIONAL LENSES OF SILTY FINE SAND
354-
3eoJ_LBROWN FINE SAND, EXTREMELY COMPACT
III-B-10
-------
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III-B-11
-------
The water sample results are shown in Table III-B-1. Generally, the
groundwater quality is good, though its slightly acidic nature means that the
water may have elevated iron contents. Also, the water pumped from boring 1
had a "swampy" odor and taste. The phosphorus levels are typical for natural
groundwater. The nitrate levels are consistent with other reported values for
mixed forest and cropland. At the Muskegon, Michigan, Wastewater Management
System, background levels of nitrates from wells in similar beach sands have
average ranges from 0.1 to 1.2 mg N/l (Demirjian and others, 1980).
TABLE III-B-1. GROUNDWATER SAMPLING RESULTS FOR POTENTIAL CLUSTER DRA1NFIELD
SITES AT PICKEREL LAKE, MI, SAMPLED ON 22 OCTOBER 1980.
Parameter
Sample location and piezometer
Charles Kreeger Warren Keller
Piezometer depth (feet) 47
Thickness of saturated
material (feet) 23.6
40
14.9
20
31
5.0
5.3
Type of sample
Temperature (°C)
pH (standard units)
Nitrate (mg N/l)
Total phosphorus (mg P/l)
Pumped
(clear)
8
6.2
0.961
0.0024
Pumped
(clear)
9
6.2
1.21
0.0036
Bailer
(filtered)
9
6.8
1.37
0.0040
Bailer
(filtered)
9
6.9
1.66
0.0018
Soil samples for laboratory analysis (Table Ill-B-2 and Appendix B) from
the Kreeger property were kept to a minimum in order to minimize costs. One
Shelby tube each from borings 1 and 3 were obtained, but the tube from boring
1 contained insufficient sample for testing. Nearly all of the soil material
encountered in borings 1 and 2 was similar to the soil material in the Lube
sample from boring 7. The vertical permeability of that sample (boring 7) was
4.1 x 10 cm/sec (3.6 in/hr), a value consistent with the particle size of
the soil material encountered. A weighted average value of 3 in/hr for
horizontal permeability was selected.
In an attempt to model a simplified system that resembles a uniform
application of water over a long, rectangular area and a drainage ditch along
one side. The Hooghoudt equation for a flat area will adequately predict what
will occur. The form of the equation utilized is as follows:
K A2 ,2,1/2
L = - (yO - yl )
III-B-12
-------
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where: L = distance from the drainage ditch to the far side of the appli-
cation area, ft
K = horizontal permeability, in/hr
q = drainage or application coefficient, in/hr
yO = allowable height of saturated material above a specific datum, ft
yl = height of the bottom of the drainage ditch above that same datum, ft
Values derived from Figure 3 are:
yO = 30 ft
yl = 18 ft
A liquid application coefficient, q, of 0.34 gal/ft2/day, 1.9 x 103 in, calcu-
lated for trench bottom was used. This coefficient assumes a conservative
percolation rate of 15 min/hr; 3 persons/house; an average flow of 65
gal/person/day; and 190 sq ft of trench bottom for every two people (per
bedroom). Substituting these values into the equation yields a distance of
390 feet from the drainage ditch (bottom of escarpment) to the far edge of the
application area. Considering the proportion of seasonal residences, the
water table would actually rise during the summer and fall during the
remainder of the year. Thus, this site would perform very well as a drain-
field site. Vertical permeabilities in the top 25 feet of material are
greater than the application coefficient and would not cause a perched ground-
water condition.
The ultimate path of the applied water is difficult to determine without
more extensive soils investigations. In general, the water would flow toward
the creek and toward the lake. Also, the rise in the groundwater table in the
area below the escarpment may be assessed only if considerably more soils
information is gained. Because the camp facilities are located on soils with
high water tables, protection of these facilities from further rises of the
water table may be deemed advisable. A drainage ditch or draintile below the
escarpment would provide a great measure of protection.
The pollutants in the septic tank effluent applied to the drainfield
would, with the exception of nitrates and chlorides, be nearly completely
removed in the soil matrix. Nitrogen in the effluent would be partially taken
up by the plant cover, denitrified, and leached to the groundwater flow
system. Denitrification and uptake could account for some losses, although
the precise percentage cannot be estimated for various soils. Denitrification
and uptake are generally greater in fine-textured soils than in sands and
gravels. Dilution is recognized as the key mechanism for achieving acceptable
levels of nitrates in groundwater below a drainfield. Downgradient from the
potential cluster drainfield site are several residences near the lakeshore
and the Camp Petosega campsites. It is likely that they all have wells that
penetrate to about 50-foot depth into the surficial sands into which the
drainfield would discharge. Because stratification of groundwaters usually
occurs, it is unlikely that excessive nitrate levels would be encountered in
any of the domestic wells. Because the depth to the water table in a large
III-B-14
-------
area below the escarpment is shallow, a considerable portion of the nitrates
could be removed by vegetation in that area. If a draintile or ditch would be
constructed below the escarpment, much of the nitrate-enriched groundwater
would be intercepted and conveyed directly to a surface outlet. The contribu-
tion of nitrates to lake eutrophication would be significant.
b. Warren Keller Property
This site (Figure III-B-7) is comprised of the southeast corner of the
property of Warren Keller located on Artesian Lane west of Ellsworth Road. It
is located in the NW% of the NE^ and the NE% of the NW% in T. 35 N. , R. 4 W. ,
sec. 34 and is under the political jurisdiction of Springvale Township. The
land to the east is owned by Ray Johnston; the land to the south is owned by
Charles Laubrick along the eastern quarter mile and by Henry Hannan along the
western quarter mile. The site plan shown was developed from the USGS
quadrangle map, the soil survey, the plat map published by Rockford Map
Publishers, and some on-site surveying. The site plan is a schematic only and
is not intended to be accurate.
The potential cluster drainfield site is presently unmowed grasses and
weeds. Some scattered small trees are present in the northeastern portion of
the area. The approximate location of an electrical power line is shown on
the site plan. The landowner has proposed construction of a residence in the
northeastern portion of the site plan. An access road from Artesian Lane is
proposed for the residence. Access to the potential area is limited at pre-
sent to lanes through the Laubrick and the Hannan properties.
The site is characterized by gently sloping topography. About 10 feet of
relief, from northwest to southeast, characterizes the site. The escarpment
represents about 35 feet of elevation difference. The soils (Kalkaska sand)
are formed in old lake beach material overlying morainal material. The topo-
graphy and soil mapping indicate that morainal material slopes from south to
north in this area. The topographic high to the south of this site is part of
this moraine. The old lake beach was probably eroded along the bottom of the
escarpment by another lake level higher than the present lake level. The
sands exposed along the escarpment exhibit the variable deposition angles
characteristic of lake beaches and dunes. The Keller and Kreeger properties
both exhibit similar geologic sources, except that the morainal material is
nearer the surface and lies at a steeper slope on the Keller property.
The soil boring logs prepared from observations by WAPORA, Inc. personnel
are presented in Tables III-B-8, III-B-9, III-B-10, and III-B-11. The
driller's logs are included in Appendix A. The three borings on the north,
borings 4, 6, and 7, show that medium and fine textured sands are found to
depths of 14, 13, and 17 feet, respectively. Thin lenses of silty sand in the
medium and fine sands occur below the clean sands. In borings 4, 6, and 7,
silty clays were encountered at depths of 21, 18, and 27 feet, respectively.
In the boring to the south, boring 5, medium and fine sands were encountered
to a depth of 8 feet, below which was encountered very compact, light brown,
medium sand that appears to be older and associated with the moraine. At a
depth of 25 feet, bluish gray, silty clay was encountered. The borings show
that lake beach material is thicker toward the escarpment (Figure III-B-12).
III-B-15
-------
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III-B-16
-------
Figure III-B-8. Soil boring 4, Warren Keller property, performed
by Geo-Tek, Inc., on October 21, 1980. Logged
by continuous split spoon sampling.
ELEV. 647.5
H DARK BROWN MEDIUM SAND TOPSOIL
1.0-
BROWN TO REDDISH BROWN MEDIUM SAND
5-
6.0-
BROWN MEDIUM TO FINE SAND
7.5- "
10-
39.0-
LIGHT BROWN FINE SAND
• LIGHT BROWN VERY FINE SAND
15- !_
LIGHT BROWN VERY FINE SAND
•LIGHT BROWN VERY FINE SAND
18.0-
LIGHT BROWN VERY FINE SAND
20^
21.0
LIGHT BROWN SANDY SILT
mSHELBY TUBE
26.0-
LIGHT BROWN MEDIUM SAND, EXTREMELY COMPACT
304
32.5-
LIGHT BROWN LAYERED MEDIUM SAND, SANDY SILT, AND SANDY CLAY
BROWN SANDY CLAY, STIFF
37.5-
BROWN AND GRAY SANDY CLAY WITH LENSE OF GRAVEL, STIFF
•EOB
III-B-17
-------
Figure III-B-9. Soil boring 5, Warren Keller property, performed
by Geo-Tek, Inc., on October 21, 1980. Logged by
auger cutting and occasional split spoon sampling.
FEET
Q ELEV. 646.2
3.0
5
8.0-
9.5.
DARK BROWN GRADING TO REDDISH BROWN MEDIUM SAND TOPSOIL
-•
BROWN MEDIUM SAND
GRAVEL AND BROWN SAND
15-
20-
LIGHT BROWN MEDIUM SAND, WITH OCCASIONAL STONES, COMPACT
mm
BRASS SLEEVE SPLIT SPOON SAMPLES
LIGHT BROWN MEDIUM SAND, COMPACT
25-_
" I BLUISH GRAY SILTY CLAY, EXTREMELY STIFF
27.0-U-EOB
III-B-18
-------
Figure III-B-10. Soil boring 6, Warren Keller property, performed
by Geo-Tek, Inc., on October 21, 1980. Logged by
auger cuttings and periodic split spoon sampling.
FEET
ELEV. 637.5
DARK BROWN MEDIUM SAND TOPSOIL
BROWN MEDIUM SAND
5+
BROWN GRADING TO LIGHT BROWN MEDIUM SAND
SHELBY TUBE, 5% RECOVERY
j SHELBY TUBE, 0% RECOVERY
13.0-
18.0-
18.5-
19.5-
LIGHT BROWN SILTY VERY FINE SAND, VERY COMPACT
SHELBY TUBE
16.5-
" LIGHT BROWN SILTY SAND, WET, VERY COMPACT
IBUFF GRAVEL
BUFF GRAVELLY SANDY CLAY, EXTREMELY STIFF
•EOB
III-B-19
-------
Figure III-B-11. Soil boring 7, Warren Keller property, performed
by Geo-Tek, Inc., on October 21, 1980. Logged by
auger cuttings and occasional split spoon sampling.
FEET
ELEV. 640.0
BROWN MEDIUM SAND
i.o-
5 —
LIGHT BROWN MEDIUM TO FINE SAND
J SHELBY TUBE
10-
>—
1
15—
ILIGHT BROWN SILTY FINE SAND, MOIST
20-
GRAVELLY LIGHT BROWN SAND
r
25+
ILIGHT BROWN SILTY SAND
• LIGHT BROWN SILTY SAND
STATIC WATER LEVEL 614.3
ILIGHT BROWN SILTY SAND
27.0-
LIGHT BROWN SANDY CLAY, WET, PLASTIC
30—I
31.0-(
BUFF TO GRAY MEDIUM SAND AND FINE GRAVEL, WITH SOME CLAY, MOIST,
32.5-JJ-EOB SLIGHTLY PLASTIC
III-B-20
-------
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In all of the borings, very little saturated, permeable material was
encountered above the aquitard. Even in the boring in which the piezometer
was placed, boring 7, only little more than 1 foot was measured. Groundwater
movement would proceed downgradient, toward the north. Topography and thick-
ness of saturated material shows that the area contributing groundwater to the
potential drainfield site is probably limited in size. The soil survey and
observations show that, below the escarpment, the water table is at the soil
surface. The soil material is sand and silty clay, similar to the soil ma-
terial encountered in the borings at somewhat the same elevations.
The results of the water sample testing are shown in Table III-B-1. The
lone sample indicates that the groundwater quality is good. The results are
comparable to the quality of the groundwater tested from the piezometers in-
stalled on the Kreeger property. The pH was slightly higher; nitrate was also
slightly higher; and total phosphorus was slightly lower. Recovery of a
sample was achieved with a bailer, and the sample was very turbid. The
piezometer had to be set down into the sandy clay in order to be able to
recover a sample. Thus, the sample may not be representative of groundwater
quality.
The results from the laboratory analysis of the soil samples are pre-
sented in Table III-B-2 and Appendix B. Shelby tube samples were obtained
from borings 4, 6, and 7, and a brass sleeve split spoon sample from boring 5.
The vertical permeability results showed a range from 7.8 x 10 cm/sec (11.0
in/hr) to 8.1 x 10 cm/sec (0.00115 in/hr). The high vertical permeability
came from the brass sleeve split spoon sample from boring 5 while the low
vertical permeability came from boring 6 of material identified as fine sand
to silty clay. The surface soil material in the three borings near the es-
carpment is characterized best by the sail sample from boring 7. The vertical
permeability was measured as 4.1 x 10 cm/sec (3.6 in/hr). Thus, similarly
to the soil material on the Kreeger property, the composite horizontal perme-
ability was assumed to be 3 in/hr. The soil material encountered in the
bottom of each of the borings effectively serves as an aquitard, because its
permeability is about 300 times less permeable, assuming that its permeability
is similar to the soil material tested from boring 6. The silty fine sand
encountered at depths of 21 to 26 feet in boring 4 and tested in the labora-
tory would contribute little to horizontal flow but can transmit water vertic-
ally at 3 times the application coefficient. Thus, the medium sand at depths
of 26 to 32.5 feet could contribute to horizontal flow.
The application of water in a drainfield was modeled by means of a sim-
plified analysis. The Hooghoudt ellipse equation modified for a sloping aqui-
tard was used for the analysis. The analysis presumes a long, rectangular
application area paralleling a drainage ditch. The form of the equation
utilized is as follows:
T *- i n-r rt "" ^ i -i Z K ~ 2. K ,.
L + 2LS y - + yl - - yO - = 0
q q q
where L, K, and q are as previously defined and
yO = allowable height of saturated material above the sloping aquitard, ft
yl = height of the bottom of the drainage ditch above the aquitard, ft
III-B-22
-------
y = the difference between yO and yl, ft
S = the average slope of the aquitard and land surface, ft/ft
Values derived from Figure III-B-12 are as follows:
yO = 17 ft
yl = 0.5 ft
y = 16.5 ft
S = 0.0345 ft/ft
The application coefficient was assumed the same as for the Kreeger property.
The calculated result is a distance of 460 feet from the bottom of the escarp-
ment to the far edge of the application area. This distance is applicable to
the area where the depth of permeable material is about 27 feet deep. Thus,
the area near borings 5 and 6 would be excluded. The area toward the north,
the proposed site of the landowner's residence appears to offer the greatest
potential. This site would perform well as a cluster drainfield site.
The applied water would percolate to the aquitard and then move downslope
to the face of the escarpment where the present groundwater surfaces. The
groundwater table below the escarpment is presently at or near the surface.
This water reenters the groundwater system or is collected by a surface drain
near Artesian Lane and both flow toward Pickerel Lake. The additional water
in this system would not appreciably affect this drainage system.
The conclusions concerning the effects of the potential drainfield on the
environment for the Keller property are similar to those for the Kreeger
property. Nitrate is the nutrient of concern at this site also. The wells in
this area, though, are cased through a thick layer of clay. Potential pollu-
tion of these wells is essentially nonexistent. Also, because the water table
below the escarpment is at or near the soil surface, uptake and denitrifica-
tion could be expected to account for greater losses. The surface drains
could also be expected to intercept and convey a sizable proportion of the
nitrate-enriched water to the lake. The effect of the nutrients from the
drainfield on eutrophication in the lake is expected to be negligible.
III-B-23
-------
REFERENCES
American Public Health Association. 1975. Standard methods for examination
of water and wastewater. 14th ed. Washington DC
Demirjian, Y.A., D.R. Kendrick, M.L. Smith, and T.R. Westman. 1980. Muskegon
County Wastewater Management System, progress report, 1968-1975. Muske-
gon County Department of Public Works, Muskegon, Michigan. EPA
905/2-80-004. Prepared for U.S. EPA, Robert S. Kerr Environmental
Research Laboratory, Ada, OK, and the Great Lakes National Program
Office, Chicago IL.
Alfred, S.D, A.G. Hyde, and R.L. Larson. 1973. Soil survey of Emmet County,
Michigan. U.S. Department of Agriculture, Soil Conservation Service, in
cooperation with Michigan Agricultural Experiment Station.
U.S. Environmental Protection Agency. 1979. Draft environmental impact
statement: Alternative waste treatment systems for rural lake projects -
Case Study Number 3, Springvale - Bear Creek Sewage Disposal Authority,
Emmet County, MI.
III-B-24
-------
APPENDIX A
DRILLER'S SOIL BORING LOGS*
*Correct boring numbers for the Keller Property are listed to the right of each
incorrect boring number, indicated as incorrect by notation.
III-B-25
-------
GEO-TEK
INC.
SUBSURFACE {EXPLORATION
PO Box 116 } Lowell. Mich. 49331 • Bus Phone: (616) 897-5581
Kreeger Property
Lo«t,o« Brroet County
Job No. _
fltrmit No..
Well Set At 47'
LOG OF BORING
Boring Numb*
Depth Drilled
SurfK* Eltv.
D»te Started .
Oalt Completi
In
FMt
•
Sample
Tvpe
3"S.T.
SNR
, 1 «
50.5' ft.
ft.
10/20/80
^10/20/80
Penetration
ASTM
01SM
122
4-3-4
3-4-5
5-4-5
5-5-6
4-4-5
4-5-4
3-4-4
3-3-3
3-3-3
3-3-4
3-3-4
3-3-3
2-3-4
2-3-4
2-4-5
5-5-9
5-5-6
5-5-6
3-3-5
2-3-6
6-6-7
5-5-7
Ground Water: + Plugging Record
=r«n.ChMf QuallS enenuntmrf «t 25'-.. ft. Baring Sutad with • EX. Soil
H.ln.r KlltZ ArttrComBletian23.5"ft. h.tween 0 ft. A SO . 5 ft
Drill R 14 45 Altar 24 hrt ft- tmnammn ft A _. ft
Sorinq M.lhod HS^ ValufM tMtWMn ft A ft
SMfioea « , ft_ „ hatwMMt ft A ft
SOIL OfSCftlPTION
Topsoil- Dark-brown, sand loam.
Sand- Loose, dark-brown, med.
Sand- Compact, dark-brown, med., with a slight binder.
Sand- Compact, brown, fine, to med.
Sand- Compact, brown, fine, silty, with slight binder.
Sand- Compact, brown, fine to med., with trace of pebbles.
Sand- Compact, brown, fine t
-------
GEO-TEK
INC.
SUBSURFACE {EXPLORATION
PO Box 116 i Lowell. Mich 49331 • Bus. Phone: (616) 897-5581
proiect Kreeger Property
Location Emmet County
LOG OF BORING
Job No. _
Ptrmit No..
Boring Numtw
Depth Drilled
Surf act Elm.
D»t« Starttd
D*t« Compel
D**>
In
f~t
4
1
t
t-
1-
|
i
• •
Sjmpta
Typ«
1
ECB
• i
• »
i •
r 1
50.5 ft.
ft.
in/?n/8Q
•dlQ/20/aC
Penetration
ASTM
D1BM
5-7-12
8-10-15
7-7-8
5-4-8
3-5-10
5-5-9
5-3-4
Ground Wrar: ( -f- Pluggmf B«cord .
Cr«« Chi.1 QUallS , E««ml.«d^5' 7 f,. •ori.gS^I^ ~,t* EK- S011
Hahwr KlltZ Aft»Ci»iiiitoiio«23.5" H. IMIMMMI 0 ft.*50'5 ft
Drill Rn 45 Afttr 24 hn: ft. telWMn ft* ft
Borinq Method H§£ Valuma hMM«« ft* It
SMUfBM (t. (MMUMH ft. A ft
•OIL OlSCMimON
Sand- Very compact, brown, fine, with a trace of pebbles and
ccc. silty sand lenses.
Sand- Compact, brown, very fine, very silty.
III-B-27
41.0'
48.0'
50.5'
-------
GEO-TEK
INC.
SUBSURFACE IEXPLORATION
PO Box 116 I Lowell. Mich. 49331 • Bus. Phone: (616) 897-5581
Proi«t Kreeaer Property
Location Bnmet County
Job No. _
Permit No..
Well Installed At 40'
LOG OF BORING
Boring Number
Depth Drilled 4H
Surface Elev.
Date Started
Date Completed in/7n/fif
Crew Chief Quails
Helper Klitz
Drill Rig 45
Boring Method.
Ground Water: +
EncounteredM 26.5 ~^_ft.
AtorComptotton 25*2" ft.
Af^2S'7" h^ 24 ft.
VolUHM
« ft
Plowing Record
Bor ing Se«ted with:
:. Soil
. between 0 ft. ft 40
. ft. ft
. ft. ft
. ft. ft
. fi.
.ft.
Dent*
In
Feet
Sample
Type
Penetration
ASTM
01SM
SOIL OISCMIPTION
6.0'
I-
^-
i
fl
26.5' L
40.0'
ECB
Sand- Damp, dark-brown, med., with a layer of brown very
sandy clay.
Sand- Dairp, light-brown, fine, to med.
Sand- Wet, brown, fine to med., with occ. lenses of fine,
silty, sand.
III-B-28
-------
GEO-TEK
INC.
SUBSURFACE IEXPLORATION
PO Box 116 I Lowell. Mich. 49331 • Bus. Phone- (616) 897-5581
Pronct _
Location
Kreeger Property
Bmmet County
Job No. _
Permit No.
LOG OF BORING
Boring Number
Depth Drilled .
Surface Elev. _
36 ft.
ft.
O.i. stated 1Q/2Q/RQ
Crew Chief Quails
Helper KlitZ
Drill Rio.
45
Boring Method HSA
Ground Weter: _(.
Encountered«tL3. 5'- ft.
After Completion 9.3" ft
Alter 12 Mrs; ft.
Volume
ft
Plugging Record
Boring SMtod with: Ex. Soil
ft. »
ft. ft
ft. ft
.ft.
.ft.
. ft.
.ft.
|0ep*
In
Feet
Sample
Type
Penetration
ASTM
01SM
•OIL oitCHirrioN
1.0'
5.0' ._
I-
h
13.5'
25
.5' ft
Topsoil- Dark-brown, sand, loam.
Sand- Dairp, med., shades of brown.
Sand- Damp, brown, med., occ. layer of med silty sand.
Sand- Wet, brown, fine, very silty.
Clay- Moist, brown, very silty, with layers of fine silty
sand.
35.0'
36.0'
5-19- 30
BCB
Sand- Ext. conpact, brown, fine.
III-B-29
-------
GEO-TEK
INC.
SUBSURFACE JEXPLORATION
PO Box 116 f Lowell. Mich. 49331 • Bus. Phone: (616) 897-5581
Proitct Keller Property
Locat.on
County
Job No. _
Ptrntit No.
LOG OF BORING
Boring Numb*
Depth Drilled
Surlac* Et*v.
0*1* Sl»rt*d
Oat* Comptoti
F**t
4
•
•
S*npto
Typ*
'
3"S.T.
JBCB
r X ^ (
37 it. .
It. I
10/21/61
^ 10/2 1/8 C
RtfMtfflttOft
ASTM
0 IBM
L/2 1/2-2
1-1-1
2-2-3
4 A £
1 *t D
5-7-6
4-4-5
3-2-3
2-2-2
2-2-2
2-2-5
4-5-4
4-4-7
5-5-7
5-7-8
6-7-9
6-4-6
11-18-22
11-14-19
12-18-26
26-24-24
11-11-9
6-12-18
6-14-16
Ground W*t*r: + Plugging Record
:»w Chial OuallS Enenunttradit .,22'.-,. '«- anring «••!•»• »ini fly. Poll
•Icltwr K^it2; AfMrCamotatlon ft. bitMMM Q " * ^7 '<
Drill R» 45 Afttt hrt ft. teMMM ft* ft
loring M.thod H.^A VoImM hMMM ft * It
SMaaaBM 99'- It hm«n*mn It* It
•OIL OI*CNIr«TIOM
Tcpsoil- Black, sand, loam.
Sand- Loose, dark -brown, med. , trace of organics.
Sand- Compact, light-brown, med.
Sand- Compact, brown, med to coarse, with layers of fine
sand.
Sand- Compact, brown, very fine, silty.
Sand- Ext. compact, brown, med to coarse.
Sand- Ext. compact, brown, med to coarse, with sane fine to
med. gravel.
Sand- Silt and clay layers, compact, brown, med sand, silty
clay.
Clay- Ext. stiff, brcwn, occ. lense of silt and gravel.
III-B-30
1.0'
6.0'
12.0'
17.5'
26.5'
31.01
32.5'
34.0'
37.0'
-------
GEO-TEK
INC.
SUBSURFACE {EXPLORATION
PO. Box 116 I Lowell. Mich. 49331
Pro,*ct Keller Property
Bus. Phone: (616) 897-5581
County
Job No. _
Ptonit No.
LOG OF BORING
Boring Number .
Depth Drilled 27 ft
Surface Elav. «L
Date Started 10/21/80
Oat. Completed 10/21/8 C
In
Feet
6.0'
3" Tube attempt
8'
Sample
Type
r-
25.0'
27.0'
BOB
Crew Chi«l
Quails
Klitz
Drill Rig 45
Boring Method HSA
Penetration
ASTM
O1SM
10-15-18
11-20-22
12-20-26
Ground Weter.
EneountM«d et
After Completion ..
After _ hrt;
Volume _
et _ ft
ft
Plugging Re
Bof ing Seeled with:
Soil
tt. *
it. ft
ft a
fl
n
»t
ft
•OIL DltCMimON
Sand- Damp, dark-brown, med.
Sand- Damp, light-brown, med., occ. stone.
Clay- Ext. stiff, brown, silty.
III-B-31
-------
GEO-TEK
INC.
SUBSURFACE IEXPLORATION
PO. Box 116 | Lowell. Mich 49331
Proi*ct Keller Property
Bus. Phone- (616) 897-5581
Location Emmet: County
LOG OF BORING
Job No. _
Pirmit No.
Boring Numbtr a JJ
Depth Drilled 19.5* »t.
Surtece Eltv. Jl-
One Started 1 Q/91/fin
Oat* Completed in/91/Sn
Crew Chief OuallS
Helper KlltZ
Drill Rig 45
Boring Method
Ground W««r:
Encountered rt None
Af»r
Vofurtw
hn;
ft.
ft
«t17' t-rp nftt
r-1 a\7
Plugging Record
Boring SMtad with: EX- Soil
0
ft. a
.ft. A
ft. a
In
Sonpto
Type
Pwwtntion
ASTM
O1SM
•OIL OI«CMI»*TION
6"
10.5'
18.0'
19.5'
3"S.T.
no recovery
3"S.T
no re<
3"S.T
overy
5-8-11
12-20-27
'BCB
Topsoil- Dark-brown, sand loam.
Sand- Darrp, brown, mad.
Sand- Very compact, brown, very fine, with layers of coarse
sand.
Clay- Ext. stiff, gray, very sandy, with pebbles and ccc.
stones.
III-B-32
-------
GEO-TEK
INC.
SUBSURFACE; EXPLORATION
Pr0)«ct
Location Emmet County
Lowell. Mich. 49331 • Bus. Phone: (616) 897-5581
Property _
Job No. _
Ptrmit No.
LOG OF BORING
Well Set At 20'
Boring Number 4^ /
Depth Drilled 21.5' It.
Surf act 6 lev.
0.1. Completed 1QZ21Z8P
ewe* Qualls.
Helper K
Drill Rig 45
Boring Method
Ground Weter: +
Encountered et 14'- ft.
After Completion H.
After hr»; ft.
Volume
ft
Pluejtag Record
tth: EX. Soil
H. a
ft. *
ft.»
ft. ft
In
FMt
Stmpto
Type
Penetration
ASTM
0 ISM
•OIL DI
-------
APPENDIX B
SOILS LABORATORY TESTING RESULTS
III-B-34
-------
III-B-35-
-------
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-------
CHAPTER IV
COST ANALYSIS
-------
A. COST VARIABILITY STUDY
1. INTRODUCTION
The selection, design, and costs of wastewater management technologies in
rural areas are significantly affected by local environmental and devel-
opmental characteristics. Comparison of alternative wastewater management
strategies developed by U.S. EPA during preparation of the Seven Rural Lake
EIS's suggested some intuitive relationships between the costs of certain
technologies for a particular community, and local factors such as topography,
soil and hydrogeological conditions, growth patterns, and density of resi-
dential development.
It behooves the sanitary engineer or small waste flows specialist to be
cognizant of these relationships as early as possible in the facilities plan-
ning process in order to optimize local capital expenditures for new or
improved wastewater management technologies and to expedite the facilities
planning process. Technology selection that reflects variable environmental
and developmental conditions within a community, and is, itself, a direct
result of such variability, is preferable and potentially more cost-effective
than a selection process that is based solely upon general assumptions regard-
ing these conditions. For example, conventional engineering wisdom suggests
that pressure sewers, if feasible, are more cost-effective than gravity sewers
for wastewater collection in flat areas. It is also generally known that
on-site wastewater management systems are more cost-effective than centralized
collection, transmission, and treatment facilities in low density residential
areas. But how flat must the topography be in order to optimize the cost-
effectiveness of pressure sewers over gravity sewers? How low does the hous-
ing density have to be in rural residential areas for on-site wastewater
management to be the technology of choice? At what density is it cost-
effective to substitute the use of one technology or set of technologies for
another? These questions can be addressed through quantification and analysis
of the relationships between wastewater management technologies, cost, site
conditions and developmental characteristics.
Clearly, under natural conditions, the topography of a particular waste-
water management district may not be homogeneously flat and its population may
not be uniformly of low density. Environmental and developmental factors work
in tandem to produce opportunities for trade-offs between competing tech-
nologies to be exploited in the interest of minimizing capital outlays at the
local level
a. Objectives
This study of facilities' costs as they are affected by environmental and
developmental conditions has three primary objectives:
1) quantify the effects of environmental and developmental variables on
the costs of certain wastewater facilities likely to be considered
for rural lake communities;
2) compare the ranges of facility costs in order to identify thresholds
of cost preference for competing technologies as they are affected by
the environmental and developmental variables;
IV-A-1
-------
3) identify those environmental and developmental variables that are
most critical to the conclusions of cost-effectiveness comparisons
between competing technologies.
A secondary objective of this study is to provide data in support of
other research tasks described in this Technical Reference Document including:
• Description of economic and environmental justification for variance
procedures.
• Effects of variance procedures on SWF agency design, manpower, and
costs.
• Review of jurisdictional, environmental, and developmental approaches
to defining planning area boundaries.
• Evaluation of segmentation in SWF planning.
b. Major Variables Affecting Wastewater Management Facilities
Costs
Variables expected to significantly affect the costs of wastewater
management facilities in rural areas include:
• Environmental constraints
- flat, steep, or rough topography
- depth to groundwater
- depth to bedrock
- soil stability in cuts greater than five feet
- soil permeability
- distance to sites suitable for small scale treatment
• Developmental constraints
- rate of growth
- housing density
- house setback from road
• Technology selection
- large-scale off-site technologies
- small-scale off-site technologies
- on-site technologies
c. Uses and Limitations of Cost Variability Study Data
Data developed during the cost variability study, in conjunction with
local knowledge of such factors as topography, soil conditions, and housing
density, may serve the pre-Step 1 or early Step 1 planning needs of wastewater
management officials. Local officials may employ cost variability data to:
• determine the preliminary economic feasibility of sewers,
• define preliminary service area boundaries for various off-site and
on-site technologies,
IV-A-2
-------
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IV-A-3
-------
• generate preliminary alternatives, and
• conduct preliminary cost-effectiveness analyses of pre-Step 1 or early
Step 1 alternatives.
The use of cost variability data to assist local facilities planning
efforts is optimized through completion of a two-phase process:
Phase I--A first-cut preliminary determination of centralized sewerage
facilities' feasibility is made by determining housing density (houses
per mile of sewer) within potential service areas of the community. This
determination will indicate whether sewers are at all feasible. On the
basis of population data alone, high density areas are generally more
cost-effectively served by centralized facilities than by small-scale
off-site facilities or on-site facilities. The converse is generally
true for low density areas, again on the basis of population data alone.
The cost-effectiveness criteria used to make preliminary decisions of
sewerage facilities' feasibility during this phase are provided by cost
tables and cost curves presented here. The end result of Phase I efforts
is a breakdown of those segments within a community that could be cost-
effectively served by centralized facilities and those that could be more
cost-effectively served by other technologies.
Phase II--With additional information about the segmented residential
areas delineated in Phase I, efforts during Phase II could indicate the
necessary combinations of technologies to cost-effectively satisfy the
wastewater management needs of the entire community. Again, tabulated
and graphed cost variability data would have to be consulted. Using
available information on the number of malfunctions, housing age, lot
size, topography and groundwater, and soil conditions on a segment-by-
segment basis, it is possible to develop preliminary cost-effective
combinations of technologies that are reasonably feasible in light of
local environmental and developmental characteristics.
Data and conclusions from this study will be useful in preparation of
Plans of Study for Step 1 applications, in delineating centralized and small
waste flows service areas on a preliminary basis and in screening preliminary
alternatives. However, cost comparisons of final alternatives should be based
on locally applicable data for unit costs and necessary technologies.
2. METHODOLOGY
The methodology used to quantify and evaluate the effects of represen-
tative environmental and developmental variables on the costs of selected
wastewater management facilities (see Table IV-A-1) is described in this
section.
This methodology involves completion of the following steps:
Step 1: Select density range
Step 2: Establish growth variables
Step 3: Identify environmental constraints
Step 4: Combine environmental constraints into scenarios
IV-A-4
-------
Step 5: Select wastewater management technologies
Step 6: Compile unit costs
Step 7: Estimate present worth per house costs of wastewater
technologies
Step 8: Tally wastewater collection, transmission and treatment
units necessary for technologies under variable growth
rates, densities and scenarios
Step 9: Combine unit present worth costs
Step 10: Prepare per house present worth data in tabular form
Step 11: Prepare per house present worth data in graphic form
Step 12: Analyze data
a. Step 1: Select Density Range
Critical among the developmental variables affecting the per residence
cost of wastewater management in rural areas is the density of homes to be
served. In low density development areas, conventional sewerage facilities
tend to be significantly more expensive than alternative collection systems
and on-site systems. The first step in this cost variability study method-
ology is the selection of a range of housing densities for which cost comple-
tion among wastewater technologies may be evaluated. With the focus on waste-
water management in rural areas, the extent of housing densities evaluated
reflects the range of lot sizes within which on-site systems are considered
feasible.
For the sake of analysis, density is defined as the number of houses that
could connect directly to one mile of collector sewer. In many rural set-
tings, the collector sewer would be constructed within road right-of-ways so
the length of sewer can be approximated by length of road. The range of
housing densities evaluated varies depending on the growth rate under con-
sideration (see Section 2b). Under an assumption of no growth (i.e., 0%),
housing densities include 25, 50, 75 and 100 houses per mile of sewer or
roadway. This range shifts upward to 38, 75, 113, and 150 houses per mile of
sewer or roadway under an assumption of future growth (i.e., 50%).
The primary determinant of housing density is lot size. The range of
housing densities used in this study is 25-100 houses per mile of sewer or
roadway. At the lowest end of the density range, 25 houses per mile, average
lot sizes would vary from approximately 1 acre to 8 acres. At or below a
density of 25 houses per mile, lot sizes are sufficiently large to accommodate
any number of on-site system configurations. At this density, on-site systems
are considered quite feasible and competitive with all alternative small- and
large-scale technologies. Therefore, an analysis of trade-offs between on-
site systems and competing technologies under varied environmental and devel-
opmental conditions is essential in order to optimize community-wide expendi-
tures for wastewater management facilities.
At the highest end of the density range, 100 houses per mile, lot sizes
are considerably smaller than they would be at a density of 25 houses per
mile. Assuming deep lots (i.e., lot depth equals 2 times lot width), on
either side of a road, average lot size could be as large as 0.5 acre. At a
density of 100 houses per mile, the competitiveness of on-site systems among
available wastewater technologies decreases considerably. Higher on-site
system implementation costs are attributed to the need for sanitary surveys,
IV-A-5
-------
community-wide repairs, and special design provisions for very small lots in
response to existing environmental constraints. In spite of these special
provisions, on-site systems at a density of 100 houses per mile are within the
competitive range in which trade-off analyses are warranted.
b. Step 2: Establish Growth Variables
Another important factor affecting the costs of competing wastewater
management technologies in rural areas is the rate at which development is
expected to occur during the planning period. Again, parameters have been
selected that typify extremes under which on-site systems could be considered
competitive. In this case, two growth figures have been used: no growth, a
condition under which 0% growth occurs over the 20-year planning period; and
future growth, a condition under which 50% growth occurs over the 20-year
planning period.
Zero percent was selected as an extreme low growth condition; a growth
rate of 50% was selected as a reasonable high end assumption since community
growth up to and including 50% is an acceptable criterion when determining
eligibility of collector sewers under the U.S. EPA Construction Grants
Program.
Any significant changes in trade-offs that might occur between two or
more wastewater management technologies under alternative growth conditions
(0% and 50%) will be examined. For example, under optimum environmental
conditions*, centralized collection, transmission, and treatment facilities
may not be competitive with on-site systems under a "no growth" scenario at
densities less than 100 houses per mile of sewer or road. Under "future
growth" conditions, cost competitiveness is achieved at approximately 90
houses per mile.
c. Step 3: Identify Environmental Contraints
Unit costs for installing sewage collection and conveyance facilities
around rural lakes can vary significantly, due to topography, soil material,
frost depth, depth to water table, road construction and residential setback
distances, and elevation differences. Physical or environmental constraints
most likely encountered by facilities planners and contractors, and the extent
to which these constraints may affect total unit costs are discussed below.
Topography. Topography in the glaciated rural lake areas of Region V can
be expected to vary locally. Wastewater management officials incorporate this
variation into the technology selection and design process, providing the
appropriate mixture of conventional and alternative sewage collection systems
as required by the rise and fall of the land. Undulating or flat terrain
generally calls for provision of pump stations, pressure sewers and force
mains to convey wastewater to treatment systems. If the terrain is uniformly
down sloping, this function can be served by gravity sewers.
Alternatively, steep gravity cuts through hilly terrain would be required
to achieve the same objective. Both approaches impart significant construc-
tion and operation costs to system users.
* Average depth of sewer cut = 8 ft.; no groundwater problems; no rock
excavation.
IV-A-6
-------
Design responses to variable topography on individual lots are analogous
to those deemed appropriate for communities or segments of communities.
Design of Excavation. The sewage collection facilities within the
rights-of-way are most affected by depth of excavation. Up to a depth of
about 15-feet sewers can be laid by use of a trench box to meet safety
requirements and to minimize widths of excavation. When solid sheeting and
bracing become necessary, primarily in deep excavations with noncohesive
soils, costs increase with the square of the depth. Thus, where sewage flows
are small, pumping is often less costly than placing deep sewers. Sewer con-
struction is usually least expensive in stiff clays because the trench walls
stand up well with minimal bracing, and groundwater is rarely costly to remove
in clay soils. Sands can be very expensive for sewer construction because
they tend to flow, which means that full sheeting and extensive bracing would
be necessary to restrain the earth pressures.
A factor that would affect the lineal foot cost of pressure sewers is
frost penetration depth. One of the assumptions of this study is that a depth
of cover of five feet would be maintained, corresponding to maximum frost
penetration depth. At this depth, a backhoe must be used for excavation. In
cases where the frost penetration depth is less, or where warm sewage will
prevent freezing, a trencher may be utilized. Trenchers, though, are cost-
effective only where underground obstructions are spaced no closer than 50
feet.
Groundwater. In sandy soils, groundwater can be very extensive. Sand
becomes "quicksand" when the groundwater flow is sufficiently extensive to
cause bouyancy to the sand particles. Once excavation proceeds into the water
table more than \ to 3 feet, dewatering by means of wellpoints or wells be-
comes necessary. Sands with fine to very fine textures are difficult to
dewater without pumping sand and causing subsidence. In course sands and
gravel, extremely large volumes of water need to be pumped, which results in
increased costs; however, well spacing may be greater. Dewatering wells are
generally less expensive than wellpoints, and the well spacing and depth are
the principal determinants of cost. A slowly permeable layer underlying the
sewer invert can double dewatering costs because two lines of dewatering wells
would be necessary where one would normally suffice. Organic soils and
lacustrine clays lack the stability necessary for maintaining grade on the
sewer line and for protecting the installed pipe. In these soils the trench
must be overexcavated, and special bedding and backfill placed. Depending on
the cost of this special material, the lineal foot cost of installing sewers
may be increased a minimal amount to greater than $10 per lineal foot.
Rock Excavation. Rock excavation can be another highly variable expense.
If the rock can be ripped, the unit cost and the lineal foot cost would be
significantly less than the unit cost used in this study. Also, if the rock
were to be excavated less than one foot in depth, the unit cost might be
significantly higher than that used in this study. Costs based on the number
of holes to be drilled, primed, and shot vary more than costs based on the
depth of the holes and charge size. Rock can vary significantly in its blast
characteristics: some rock is "tough," which means it absorbs the blast and
does not fracture cleanly; and some rock is brittle with many existing frac-
ture lines and thus may fracture cleanly and easily.
IV-A-7
-------
d. Step 4: Combine Environmental Constraints into Scenarios
In this step, U.S. EPA has systematically incorporated representative
physical/environmental constraints (discussed in Section 2c), or combinations
thereof, into 8 "scenarios." These scenarios depict those physical con-
straints that are likely to be encountered and that were expected to signi-
ficantly affect costs. For pre-Step 1 or early Step 1 facilities planning
purposes, these scenarios provide local officials with sufficient framework
within which the preliminary economic feasibility of sewers may be assessed,
and preliminary alternatives may be developed in light of varying environ-
mental conditions.
The scenarios account for the following potential physical constraints:
• topography,
• average depth to groundwater,
• average depth to bedrock, and
• unstable soil.
Topography. For purposes of this study, topographical constraints are
classified as shown in Table IV-A-2.
Average Depth to Bedrock. In two scenarios with steep and rough topo-
graphy, bedrock is encountered at 2 feet (Scenario 8) and 6 feet (Scenario 6).
TABLE IV-A-2. EFFECT OF TOPOGRAPHY ON SEWERAGE SYSTEM DESIGN
Classification Technology design response Scenario
Flat Minimim grade requirements for con- 4, 5, and 7
ventional gravity sewers may necessitate
pump stations dependent on costs of
dealing with groundwater conditions.
Small diameter (4 inch) effluent sewers
may offer a cost advantage over conven-
tional gravity sewers because of com-
parably shallower grade allowed.
Optimum" Assumes 8 ft. average depth of cut 1
(a.d.c.), with minimum of 6 ft. cut.
Steep Sewer transects steep hills which re- 2
quires cuts of up to 30 ft., with
16 ft. a.d.c.
Rough Maximum depth of cut exceeds 30 ft., 3, 6, and 8
requiring one pump station and force
main per mile of collector sewer.
"" Optimum for sewers.
IV-A-8
-------
Soil Unstable. In Scenario 4, soils are not sufficiently stable in cuts
greater than 5 feet. It is assumed in this instance that imported fill is
needed to replace 1,000 feet of peat soil.
A scenario composite of environmental conditions most likely to affect
the costs of wastewater management facilities in rural areas is shown in Table
IV-A-3.
e. Step 5: Select Wastewater Management Technologies
Wastewater management technologies for which cost ranges have been devel-
oped in this study are listed in Table IV-A-1. Collection, transmission and
treatment systems included among these technologies represent a full range of
feasible large-scale and small-scale (including on-site system) responses to
the variable environmental and developmental conditions that exist in Region
V.* Since the costs of conventional collection facilities may represent as
much as 80 percent of the total capital costs for wastewater management sys-
tems in rural areas,''1'* careful consideration has been devoted to selection of
several technologies that minimize or eliminate the distance over which sewage
must be collected and transmitted via interceptors, force mains and/or pump
stations to treatment systems. Large- and small-scale technologies will
become increasingly complex as more environmental constraints have to be
neutralized.
Included among the systems evaluated in this study are the on-site tech-
nologies selected for various scenarios at 10%, 20%, and 50% replacement
levels (Table IV-A-4). These replacement levels were developed in accordance
with assumed failure rates for existing on-site systems of 10°/0, 20%, and 50%.
Technology mixes shown in Table IV-A-4 are increasingly complex from left to
right as higher failure rates indicate relatively greater site limitations.
f. Step 6: Compile Unit Costs
With the definition of environmental and developmental variables and
selection of feasible rural wastewater management technologies completed, the
next step in the methodology initiates the process by which the effects of
these variables upon the costs of competing technologies are determined. It
involves the compilation of unit costs for large-scale and small-scale waste-
water systems from several sources including local contractors, construction
guides, state officials, U.S. EPA cost data, and U.S. EPA's Seven Rural Lake
EIS's. Extremely high or extremely low unit costs were not compiled. This
effort was coordinated with that required to prepare the Technology "Fact
Sheets" in Chapter 1 of the Technical Reference Document.
The feasibility of these technologies was determined by U.S. EPA during
preparation of the Seven Rural Lake EIS's, on the basis of cost-effective-
ness, environmental factors and implementation considerations.
** Based on a recent review of approximately 300 facilities plans for rural
communities in the United States (U.S. EPA, 1970).
IV-A-9
-------
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IV-A-10
-------
TABLE IV-A-4. ON-SITE SYSTEM TECHNOLOGIES FOR VARIOUS SCENARIOS AT 10%, 20%, and 50% REPLACEMENT
LEVELS.
Scenario
10% Replacement
20% Replacement
50% Replacement
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
10% new ST/SAS1
(45 perc)2
5% flow reduction
(minimum)
10% new ST/SAS with
gravity dose
10% flow reduction
(minimum)
10% new shallow
(30 perc) placement
10% flow reduction
(minimum)
10% shallow
(30 perc) placement,
gravity dosed ST/SAS
10% flow red
(minimum)
10% pressure dosed
10% maximum flow
reduction
10% gravity dosed
oversize mounds,
alternate
10% maximum flow
reduction
10% curtain drains
reduction
10% new ST/SAS
(60 perc)
10% oversize
10% flow reduction
(minimum)
10% flow reduction
(maximum)
10% new ST/SAS with
gravity dose
(45 perc)
10% as above with
alternating fields
also
10% flow red
(minimum)
10% flow red
(maximum)
20% new shallow
(60 perc) placement
ST/SAS
10% flow red
(minimum)
10% flow red
(maximum)
20% shallow
(60 perc) placement,
gravity dosed
10% flow red
(minimum)
10% flow red
(maximum)
20% dosed mounds
20% maximum flow
reduction
10% gravity dosed
oversize mounds,
alternate
10% curtain drains
10% holding tanks
20% maximum flow
reduction
15% new ST/SAS
25% over size
(120 perc)
8% oversize * dosed
2% holding tank
20% flow red
(minimum)
30% flow red
(maximum)
20% new ST/SAS with
gravity dose
(45 perc)
30% as above with
alternating fields
also
20% flow red
(minimum)
30% flow red
(maximum)
40% shallow
(60 perc placement
ST/SAS
10% holding tanks
30% flow red
(minimum)
20% flow red
(maximum)
40% shallow
(60 perc) placement,
gravity dosed
10% holding tanks
20% flow red
(minimum)
30% flow red
(maximum)
30% dosed mounds
20% holding tanks
50% maximum flow
reduction
30% gravity dosed
oversize mounds,
alternate
30% curtain drains
20% holding tanks
50% maximum flow
reduction
ST/SAS = Septic tank/soil absorption system.
45 perc = percolation rate of 45 minutes per inch.
IV-A-11
-------
On-Site Systems and Cluster Systems. A total of 25 certified contractors
in Region V, identified through contact with 2 local health agencies in each
state, were consulted to obtain.unit costs (capital and operation and main-
tenance) for on-site system and cluster system components including septic
tanks, piping, and drainfields. Unit costs of other major system components
including dosing pumps were extracted from the literature. The majority of
unit costs for flow reduction devices included in the on-site system tech-
nologies were compiled from manufacturers. Several of these costs were also
extracted from the literature. Land costs for on-site and cluster systems
were assumed to be $500 per acre, identical to those used for costing of land
application systems. Costs for detailed site analyses, which were included
among the capital and operation and maintenance costs for on-site systems,
were derived from costs for similar analyses recommended by U.S. EPA in the
Seven Rural Lake EIS's. All unit costs for on-site and cluster systems were
upgraded to July 1980 dollars using the ENR construction cost index of 3260.
land Application Systems. Unit costs for land application systems, which
include collection, transmission, and treatment systems, were compiled from
the literature.
Land treatment costs for three different systems (slow rate, rapid infil-
tration, and overland flow) were estimated by using cost curves presented in
"Cost of Land Treatment Systems," U.S. EPA 430/9-75-003, revised September
1979.
The cost data were updated to July 1980 using the following indexes and
unit costs.
EPA sewage treatment plant index 362.1 _ „ _,
177.5 ~
EPA sewer index 387.4 _
192.2
Industrial material wholesale price 275.6 _ _ „
index 120
Labor cost $15/hr including fringe benefits (U.S. EPA, 1979)
Power cost $0.04/KWH (U.S. EPA, 1979)
Land cost $500/acre
Unit cost for piping, excavation, fittings and sewage collection and
transport were obtained from Means, 1979.
Centralized Transmission and Treatment Systems. In order to develop
estimates for transmission and treatment facilities in new centralized waste-
water systems, cost data were extracted from six of the seven alternatives
reports prepared by Arthur Beard Engineers, Inc., for the Seven Lake EIS's.
These engineering reports provided separate cost data for treatment and col-
lection facilities. Collection facilities (collector sewers, interceptors,
pump or lift stations, force mains, pressure sewers and pressure units) were
costed for both present and future construction in the reports.
IV-A-12
-------
In order to distinguish between local collector sewers and facilities
that serve transmission functions, the collection facilities were divided into
three groups and their respective capital, operation and maintenance, and
salvage values tabulated as follows:
• Eight-inch gravity sewers, pressure units, house sewers, small pumping
stations and pressure sewers located in developed areas were con-
sidered to be wholly for collection. Their costs were not included as
non-collection costs.
• Facilities located in developed areas but sized larger than the mini-
mum were identified. The incremental capital and operation and main-
tenance costs above similar but minimum-sized equipment were included
as noncollection costs.
• Costs for facilities located outside of developed areas or for those
that have transmission as their primary purpose were included as
noncollection costs.
Facilities projected for construction after the initial year of operation were
not included as noncollection costs since they were all collection sewers or
house sewers.
Salvage values were figured by straight line depreciation with structures
(all sewers, force mains, and 50% of pumping stations) assumed to have a
50-year useful life, and mechanical equipment (50% of pumping stations)
assumed to have a 20-year useful life.
Present worths for treatment and transmission facilities were calculated
for a 20-year period at an interest rate of 7-1/8%.
Present worths were inflated to a 1 July 1980 ENR Index of 3,260.
Collection Facilities. Unit costs for the following wastewater collec-
tion technologies were extracted from Means, 1979:
• conventional gravity sewers,
• small diameter gravity sewers with septic tanks,
• pressure sewers with septic tank effluent pumps,
• pressure sewers with grinder pumps.
g. Step 7: Estimate Present Worth Per House Costs of Wastewater
Technologies
The estimation of present worth per house costs in Step 7 facilitates the
identification of trade-off points between large-scale, small-scale and on-
site system approaches to rural wastewater management under varying growth,
density and site conditions. The procedures followed in the estimation of
these costs for selected groups of technologies are described below.
IV-A-13
-------
(1) On-Site Systems, Cluster Systems and Land Application
Systems
Capital and operation and maintenance unit costs compiled and updated in
Step 6 were converted to present worth (pw) unit costs (capital dollars + pw 0
& M dollars - pw salvage value). The present worth costs for an entire one-
mile segment were then converted to a per house present worth by dividing by
the number of houses present at the end of the 20-year design period.
Future Growth. In order to calculate costs for future growth, a 50%
growth rate was assumed to occur uniformly over the 20-year project life. The
costs for future growth are therefore related to density and not failure
rates. Two future growth costs were calculated. The first assumes all future
systems to be standard 60 minutes per inch (MPI)perc ST/SAS. The second
method assumes that a mix of technologies similar to those used in developing
costs for individual segments will be installed for future systems. Future
costs were calculated by multiplying the present worth of one system con-
structed per year (for 20 years) by the number of systems added per year.
This incremental cost for future growth was then added to the total present
worth (TPW) for each one-mile segment to obtain a TPW per segment with 50%
growth. Future growth-mixed technology means that the cost of a system
assumed to be constructed annually was developed from the costs of the various
technologies used for specific segments rather than a standard system
(ST/SAS - 60 MPI perc rate). The TPW costs with future growth can be compared
to similar costs for sewered alternatives to determine trade-off points for
sewering vs. non-sewering at various densities and environmental conditions.
For land application systems, the present worth computations were based
on the following:
Planning period 20 years
Discount rate 7.125%
Service life
Structural components including roads,
fencing, and piping 50 years
Mechanical components 20 years
Spray irrigation equipment 30 years
The calculation of present worth unit costs in this step initially served
to facilitate subsequent estimation of present worth costs for combinations of
collection, transmission and treatment technologies (Step 9).
(2) Centralized Transmission and Treatment Technologies
The estimation of present worth costs per house for centralized waste-
water transport and treatment facilities involved the analysis of data
describing the relationship between house densities and present worth facili-
ties costs per house. Design and cost data developed during the Seven Rural
Lake EIS provided the basis for this analysis from which July 1980 per house
present worth values will be determined.
IV-A-14
-------
In the analysis, the present worths of transmission/treatment non-
collection facilities were divided by the design year (2000) dwelling unit
equivalents for each of six communities studied in the Seven Rural Lake EIS.*
This present worth per dwelling unit is plotted in Figure IV-A-1 against
number of dwelling units per mile of collector sewer (including non-
interceptor force mains, pressure sewers and gravity sewers in presently
developed segments).
While the treatment and transport elements of this non-collector present
worth vary widely as reflected in the entries of Table IV-A-5, and do not
correlate with either total community dwellings or with density (dwelling
units per mile of sewer in developed areas), the total non-collection present
worths do correlate with density as shown in Figure IV-A-1. Because of
economies of scale, the curved line passing through these points probably best
reflects the actual relationship between housing density and cost per house.
The linear regression drawn through the points, however, provides a reasonable
approximation of the relationship within the range of densities involved, 30
to 130 units per mile.
Based on this linear regression, the following present worth values were
used in the cost variability study for treatment and transport elements in
centralized collection/transmission/treatment alternatives:
Density Cost
Dwelling Units/Mile July 1980 Present Worth
of Collector Sewer Per Design Year Dwelling Unit
25 3,712
38 3,392
50 3,097
75 2,482
100 1,866
113 1,546
150 636
h. Step 8: Tally Wastewater Collection, Transmission and
Treatment Units Necessary for Technologies Under Variable
Growth Rates, Densities and Scenarios
Step 8 involved the assemblage of discrete collection, transmission and
treatment units which comprise various wastewater technologies or systems
suitable under different growth conditions, densities and environmental con-
straints. Technology units serving one-mile segments at densities of 25, 50,
75, and 100 (0% growth) and of 38, 75, 113, and 150 houses/mile were tallied.
The degree of complexity in technology was directly proportional to the degree
of environmental constraint under evaluation. An example of this relationship
between environmental limitations and technological responses for on-site
systems is shown in Table IV-A-4.
Six communities include: Crooked/Pickerel Lakes, MI; Salem Utility
District No. 2, WI; Steuben Lakes, IN; Green Lake, MN; Nettle Lake, OH;
and Otter Tail Lake, MN.
IV-A-15
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IV-A-17
-------
i. Step 9: Add Present Worth Unit Costs
All per house present worth costs for wastewater collection, transmission
and treatment units in large-scale, small-scale and on-site systems, assembled
in Step 8, were added in this step. With development of per house present
worth cost figures completed in Step 9, the first objective of the cost vari-
ability study is achieved. The first objective is to quantify the effects of
environmental and developmental variables on the costs of selected rural
wastewater facilities. Remaining efforts (Steps 10-12) involve presentation
and analysis of cost variability data.
j. Step 10: Prepare Per House Present Worth Data in Tabular
Form
Per house present worth dollars for various technologies and combinations
thereof, by housing density, by growth rate, and by scenario (which were added
in Step 9), were tabulated for presentation. Tabulated data were presented
for these technologies:
• collection only,
• centralized collection, transmission and treatment,
• collection, transmission and land application,
• collection, transmission and cluster systems, and
• on-site technologies.
The format used to present this information is shown in Table IV-A-6.
k. Step 11: Prepare Per House Present Worth Data in Graphic
Form
A major effort in the cost variability study involved the plotting of
cost data that were calculated and tabulated through Step 10. In Step 11, 138
graphs were prepared illustrating the effects of environmental and devel-
opmental variables on the present worth costs of several rural wastewater
management technologies. These graphs are classified and quantified in Table
IV-A-7.
An extensive amount of graphic data has been prepared to:
1) Enhance interpretation of data developed during the cost variability
study. Curves contained in the graphs concurrently depict cost
relationships between technologies, growth rates, housing densities
and scenarios.
2) Facilitate achievement of the second objective of the cost vari-
ability study (i.e., compare the ranges of facility costs in order to
identify thresholds of cost preference for competing technologies as
they are affected by environmental and developmental variables).
IV-A-18
-------
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TABLE IV-A-7. GRAPHIC DATA PREPARED IN COST VARIABILITY STUDY
Number of Graphics
Type of graph @ 0% growth @ 50% growth Total
Technology graphs 18 18 36
Scenario graphs 40 40 80
Cost-effective option graphs 8 8 16
Trade-off analysis curves N/A* N/A 6
138
* N/A = Not applicable.
3) Facilitate use of cost variability study data by wastewater manage-
ment officials in pre-Step 1 or early Step 1 decision-making.
Graphic material prepared in Step 11 is briefly described below.
Technology graphs. "Technology graphs" illustrate the relationships
between housing densities and per house present worth costs of selected
technologies by scenario. Each technology graph depicts this relationship for
one type of technology and eight scenarios. Each curve on the technology
graph represents one scenario. Technology graphs would be most useful to
wastewater management planners who are interested in determining the effects
of environmental constraints (8) on one (1) type of technology under 0% or 50%
(or both) growth conditions. The eight scenarios are listed in Table IV-A-3.
A "technology" here includes a component or combination of components of a
wastewater management system. A "system" is composed of a complete range of
wastewater management facilities including wastewater collection, transmis-
sion, or transport and treatment. Cost curves were developed for these tech-
nologies :
• collection technologies (no transmission or treatment);
conventional gravity sewers,
small diameter gravity sewers/septic tanks,
pressure sewers w/septic tank effluent pumps,
pressure sewers w/grinder pumps;
• centralized collection, transmission, and treatment systems;
• collection, transmission and land application by rapid infiltration,
slow rate or overland flow methods;
• collection, transmission and cluster systems; and
• on-site technologies for 10%, 20%, and 50% replacement levels.
By definition, "collection technologies" do not constitute a wastewater
management system. However, since collection components may comprise as much
as 80% of total capital costs for centralized wastewater management systems,
conventional and alternative collection technologies are included in the cost
IV-A-20
-------
variability study. The collection technology curves can also be used where
transmission and treatment facilities are already constructed so that cen-
tralized alternatives require Only the construction of collector and house
sewers. Examples of technology curves describing relationships between hous-
ing density (houses/mile of collector sewer) and per house present worth costs
under 0% and 50% growth conditions are shown in Figures IV-A-2 and -3,
respectively.
Scenario Graphs. Examples of "scenario graphs" prepared during the cost
variability study are illustrated in Figures IV-A-4 and -5. These curves
present the same information as that contained in the technology curves except
that they are organized by scenario rather than by technology (i.e., one
scenario and several technologies). Scenario graphs may prove their useful-
ness in the wastewater management planning process by indicating cost
advantages of one or more technologies over others under an assumed set of
environmental constraints (i.e., a scenario). This information is presented
for both 0% and 50% growth conditions.
Cost-Effective Options. Cost-effective option graphs represent a dis-
tribution of information presented in the scenario graphs. Each cost-
effective option graph depicts the most cost-effective large-scale and small-
scale off-site and on-site technologies for a given scenario. There are 16
graphs in all: 8 graphs for the 8 scenarios under 0% growth conditions, and 8
graphs for the 8 scenarios under 50% growth conditions.
1. Step 12: Analyze Data
The last step in the methodology is an analysis of all tabular and
graphic data developed to achieve the third objective of the cost variability
study (i.e., to identify those environmental and developmental variables that
are most critical to the conclusions of cost-effectiveness comparisons between
competing technologies).
3. ASSUMPTIONS
The development of cost ranges for large- and small-scale wastewater
management facilities that are evaluated in the cost variability study has
been based on an assortment of design and economic assumptions. Assumptions
for each of the following technologies are discussed in this section.
o On-site systems
o Cluster systems
o Land application systems
o Centralized collection, transmission and treatment facilities
General assumptions universally supporting all cost-effectiveness
analyses conducted in this study are cited initially.
a. General Assumptions
1. The cost variability study is based on the following economic para-
meters :
IV-A-21
-------
TECHNOLOGY CURVE EXAMPLE
Collection, Transmission,
and Land Application
@ Rapid Infiltration
0% Growth
20,000
18,000
16,000
{/, 14,000
3
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TQ = Collection, Transmission, and
Land Application by Rapid In-
filtration Method
1 = Scenario 1
I
50 75
HOUSES/MILE OF COLLECTOR SEWER
100
Figure IV-A-2.
Graph used to illustrate 20 year present
worth cost (per house) vs. housing density
for selected technologies for 8 scenarios;
growth rate over 20 year period = 0%.
IV-A-22
-------
20,000
18,000
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38
TECHNOLOGY CURVE EXAMPLE
Collection, Transmission,
and Land Application
@ Rapid Infiltration
50% Growth
L50
Collection, Transmission, and
Land Application by Rapid In-
filtration Method
Technology T, 0% Growth
Technology T, 50% Growth
Scenario 1
50
I
I
75
113
150
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
FUTURE 50%
PRESENT 0%
Figure IV-A-3.
Graph used to illustrate 20 year present
worth cost (per house) vs. housing density
for selected technologies for 8 scenarios;
growth rate over 20 year period = 50%.
IV-A-23
-------
SCENARIO CURVE EXAMPLE
Scenario 1
Collection, Transmission,
and Land Application Systems
0% Growth
30,000
18,000
16,000
to 14,000
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_L
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HOUSES/MILE OF COLLECTOR SEWER
100
Figure IV-A-4.
Graph used to illustrate 20 year present
worth cost (per house) vs. housing density
for selected technologies for 8 scenarios;
growth rate over 20 year period = 0%.
IV-A-24
-------
20,000
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Collection, Transmission,
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50% Growth
Rl
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RI,
RI
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150
FUTURE
50 75
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PRESENT
Figure IV-A-5 .
Graph used to illustrate 20 year present
worth cost (per house) vs. housing density
for selected technologies for 8 scenarios;
growth rate over 20 year period = 50%.
IV-A-25
-------
• Planning period = 20 years
• Discount rate = 7.125%
• Service life - structures and sewers = 50 years - mechanical
equipment = 20 years
• Construction cost index = 3260 ENR, 1 July 1980
• All final cost results expressed as July 1980 present worth
• Capital costs are derived by multiplying construction costs by 1.2.
The additional 20% includes costs for administration of the project,
legal fees, and project contingencies.
2. Segments are one mile in length. For centralized and small-scale,
off-site alternatives, the point of flow concentration is the end of the
segment.
3. Two rates of growth are assumed for all technologies in this study:
• No growth = 0%
• Future growth = 50%.
4. Housing density @ no growth =
25, 50, 75, and 100 houses/mile.
Housing density @ future growth =
38, 75, 113, and 150 houses/mile.
5. Population, housing and flow assumptions for a range of housing
densities are listed in Table IV-A-8. The length of house sewers assumed with
the various densities is also listed.
b. On-Site Systems
In addition to the general assumptions described at the beginning of
Section 2, the following parameters were used in the development of on-site
system costs.
1. Unit costs for on-site systems are adopted from available literature
and Region V contractors' estimates.
2. Unit present worth costs are calculated after updating unit operation
and maintenance construction costs to July 1980 dollars.
3. Straight line depreciation is assumed for calculating salvage values.
4. Unit operation and maintenance costs include only those costs
associated with the upkeep of the system. No costs for the small
waste flows (SWF) district or monitoring are included.
IV-A-26
-------
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IV-A-27
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5. Administrative and monitoring costs associated with SWF management
are excluded from the analysis altogether, as similar costs are not
included for centralized alternatives.
6. Unit costs for flow reduction include the following: minimum flow
reduction - toilet tank dams (2 sets), faucet aerators (3), low-flow
shower heads (2); maximum flow reduction - air assisted toilet (1),
air assisted shower (1), and faucet aerators (3).
7. The detailed site analysis costs were developed for three replacement
levels: 10%, 20%, and 50%.
8. Detailed site analysis costs per house are based on a one-mile seg-
ment with 100 homes per mile.
9. When estimation of certain items in the detailed site analysis is not
possible on a per mile basis, average estimated costs from the Seven
Rural Lake EIS's are used. These costs are calculated on a per house
basis, averaged, and applied to the 100 homes in the segments. Costs
that were calculated in this manner include: fluorescence and
groundwater meters, field sampling equipment, paper supplies, cameras
and film, report production, communication, graphics, and report
preparation.
10. Future growth is 50% (spread uniformly over the 20-year design
period) .
11. Future growth cost calculations assume that new systems will include
septic tank/soil absorption systems (ST/SAS) (60 perc) , and alterna-
tive systems. These assumptions allow two present worth costs to be
used independently of one another.
12. Future growth costs are calculated by multiplying the present worth
cost of constructing one system per year for 20 years by the number
of systems to be replaced per year.
c. Cluster Systems
1. Cluster system unit costs are derived from the literature and con-
tractors' bid sheets.
2. A cluster system includes drainfield, gravity siphons and dosing
chamber, monitoring wells, and land.
3. Costs are developed for 50,000, 30,000, 20,000, 10,000, and 2,000
4. Drainfield design is based on using a loam soil with a percolation
rate of 45 MPI which yields an application rate of 0.45 GPD/SF.
5. The application area includes 50% more drainfield than required.
This provides for the construction of 3 fields: 2 fields are in
operation while a third is resting and acting as an emergency backup.
Land area includes a 25 foot buffer around the drainfield.
IV-A-28
-------
6. Cost of land is assumed to be $500/acre to maintain comparability to
other off-site technologies.
7. Drainfield trenches are assumed to be 3 feet wide with 7 feet between
trench centers.
8. Monitoring wells are included in each estimate as follows:
Sewage flow (gpd) Number of monitoring wells
50,000 3
30,000 3
20,000 2
10,000 2
2,000 1
9. Operation and maintenance costs are estimated at $100 per monitoring
well per year. Other operation and maintenance costs, such as
pumping individual septic tanks, are not included.
10. Hydrogeologic surveys are included in the estimated costs.
11. Land values are assumed to increase 3% per year in order to calculate
salvage values in accordance with the cost-effectiveness guidelines
(Appendix A 40 CFR 35).
d. Land Application Systems
The basic design assumptions and unit processes for land application
systems* involving treatment by rapid infiltration, slow rate, and overland
flow are described for each system as follows:
• Rapid Infiltration
Design application rate 10 in/week
Period of application 52 weeks
Storage 30 days
The rapid infiltration system includes a stabilization or facultative
pond as preapplication treatment followed by storage for 30 days. The pre-
treated wastewater is pumped out of the pond and transmitted to the infil-
tration basins by 250 feet of force main. The treated wastewater is chlori-
nated prior to application on land. The present worth per dwelling unit for
three different design flows is as follows:
Design Flow No. of Dwelling PW/Dwelling
(GPD) ($)
200,000 114 2,340
300,000 150 2,120
500,000 225 1,700
Land application systems in this study include wastewater collection,
transmission and treatment components.
IV-A-29
-------
• Slow Rate with Solid Set Sprinklers
Design application rate 1 in/week
Period of application 26 weeks
Storage 180 days
The slow rate system includes a stabilization of faculative pond as
preapplication treatment, followed by storage for 180 days. The pretreated
wastewater is designed to be pumped out of the pond and transmitted to solid
set sprinkers. The transmission is by 1,000 feet of force main. The treated
wastewater is chlorinated prior to application on land. The present worth per
dwelling unit for three different design flows is as follows:
Design Flow No. of Dwelling PW/Dwelling
(GPD) ($)
200,000 113 4,190
300,000 150 3,850
500,000 225 3,330
• Overland Flow
Design application rate 4 in/week
Period of application 26 weeks
Storage 180 days
The overland flow system includes a stabilization or facultative pond as
preapplication treatment followed by storage for 180 days. The pretreated
wastewater is designed to be pumped out of the pond and transmitted to gated
pipe for distribution on overland flow terrace. The transmission to the
application site is by 1,000 feet of force main. The treated wastewater is
chlorinated prior to application on land. The overland runoff is collected in
ditches along the bottom of terrace. Cost of disposing of the collected
runoff is not included in the estimate. The present worth per dwelling unit
for three different design flows is as follows:
Design Flow No. of Dwelling PW/Dwelling
(GPD) ($)
200,000 113 2,860
300,000 150 2,580
500,000 225 2,150
e. Centralized Collection, Transmission and Treatment Facilities
Assumptions used in the development of costs for centralized (large-
scale) collection, transmission, and treatment facilities during this task are
based upon general design assumptions relevant to those facilities that were
formulated during U.S. EPA's preparation of the Seven Rural Lake EIS's. Key
design assumptions, upon which costs for wastewater collection facilities
examined in this study are based, are presented in Table IV-A-9. These faci-
lities include:
• conventional gravity sewers,
• small diameter gravity sewers w/septic tanks,
• pressure sewers with septic tank effluent pumps (STEP), and
• pressure sewers with grinder pumps.
IV-A-30
-------
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IV-A-31
-------
1. The determination of the percent shoring for gravity collection lines
is performed on a segment basis. Ten percent less shoring is required
for force mains and low pressure sewers due to their shallower average
depth.
2. All pressure sewer lines and force mains 8 inches or less in diameter
will be PVC SDR26, with a pressure rating of 160 psi. Those force
mains larger than 8 inches in diameter are constructed of ductile iron
with mechanical joints.
3. Cleanouts in the pressure sewer system will be placed at the beginning
of each line, and thereafter, one every 500 feet of pipe in line.
Cleanout valve boxes will contain shut-off valves to provide for
isolation of various sections of line for maintenance and/or repairs.
4. The pumping units investigated for the pressure sewer system utilized
effluent and grinder pumps. Both units include a 2 by 10 foot basin
with discharge at 8 feet, control panel, visual alarm, mercury float
level controls, valves, rail system for removal of pump, antiflotation
device, and the pump itself. The grinder pump is a 2 hp pump with a
total dynamic head of 90 feet. The effluent pump is manufactured in a
1, 1^ or 2 hp pump.
4. RESULTS
Cost variability study results, developed according to the methodology
described in Section 2 and based upon the assumptions identified in Section 3,
are presented and discussed here. The results indicate, via cost tables and
graphs, the effects of housing density, environmental constraints and growth
rate on the per house total present worth costs of selected off-site and
on-site and wastewater management technologies.
a. Technology Graphs
Each technology graph prepared during the cost variability study shows
the total present worth cost per household of one rural wastewater management
technology as affected by eight different environmental constraints, two
growth rates and housing densities which range from 25 to 150 houses per mile
of roadway or collector sewer. Each curve on a technology graph represents
one scenario or set of limiting environmental conditions.
Large-scale off-site, small-scale off-site, and on-site technologies
examined in the technology graphs were described in detail in Table IV-A-1.
Collectively, general technology categories that have been assessed include:
• Collection only (no transmission or treatment)
• Collection, transmission, and centralized treatment
• Collection, transmission, and land application
• Collection, transmission, and cluster systems
IV-A-32
-------
• On-site technologies.
The effect of four (4) different collection-technologies on the costs of
large-scale and small-scale off-site wastewater management systems will be
examined carefully.
The eight scenarios addressed in the cost variability study and depicted
on the technology graphs include the following environmental constraints (and
responses to constraints) which are most determinative in affecting technology
costs:
Scenario 1 - 8-foot average depth of cut
Scenario 2 - 16-foot average depth of cut
Scenario 3 - 8-foot average depth of cut (with one pump station and force
main)
Scenario 4 - Flat topography, 6-foot average depth to groundwater (and
imported fill needed to replace 1,000 of peat soil
Scenario 5 - Flat topography and 6-foot average depth to groundwater
Scenario 6 - Topography necessitates 1 pump station and force main;
6-foot average depth to bedrock
Scenario 7 - Flat topography
Scenario 8 - Topography necessitates/pump station and force main; 2-foot
average depth to bedrock (50% of houses are low relative to
sewer and require septic tank effluent pumps).
Two growth rates, 0% and 50%, are examined for their effect on per house
present worth costs of wastewater technologies. These figures represent two
hypothetical rates of growth for the 20-year planning period.
The 36 technology graphs (Figures IV-A-4-1 through IV-A-4-36) presented
in this section are indexed in Table IV-A-4-1. Tabulated background data for
each graph are also indicated in Table IV-A-4-1.
The following discussion of technology graph results is organized by
major technology category.
b. Collection Technologies (No Transmission or Treatment)
It was stated earlier that the cost of a conventional collection system
generally represents more than 80% of the total capital cost of wastewater
management facilities in rural areas. Lower housing densities in rural areas,
with attendant greater lengths of sewer per system user, and unfavorable soil
and topographic conditions, can result in excessive costs per household for
sewerage collection facilities. Alternative collection systems are less
sensitive to some of the constraints that contribute to excessive cost of
conventional sewers. For these reasons, U.S. EPA has undertaken an evaluation
IV-A-33
-------
of collection systems (with no sewage transmission and treatment) as part of
its cost variability study. These systems include the following alternatives
to conventional gravity sewers:
• small-diameter or 4-inch, gravity sewers
• pressure sewers with septic tank effluent pumps
• pressure sewers with grinder pumps.
The per house total present worth costs for conventional gravity sewers,
small-diameter gravity sewers, pressure sewers with septic tank pumps, pres-
sure sewers with grinder pumps, and under 0% and 50% growth rates for the
20-year planning period are shown in Figures IV-A-4-1 through 4-8. Backup
data for these graphs are included in Table IV-A-4-2 through 4-5. The cost
data in Figures IV-A-4-1 and 4-2 for conventional gravity collection sewers
indicate that the total present worth costs per house are highest for
Scenarios 2, 4, and 6. At lower housing densities (25 and 38 houses per
mile), the costs of small-diameter gravity sewers (Figures IV-A-4-3 and 4-4)
are slightly (i.e., 10%) less than those of conventional gravity sewers for
all scenarios, and under both 0 and 50% growth conditions. At high densities
(100 and 150 houses per mile), the reverse is true for all scenarios except 4,
5, and 7. In these three scenarios, representing flat topographical condi-
tions, the costs of conventional gravity sewers are approximately 15% more
than small-diameter gravity sewers. This cost difference is due to the dif-
ferent depths of cut required in flat topography for conventional and small-
diameter gravity sewers. For conventional gravity sewers, the depth of cut
would be between 8 and 24 feet, to provide adequate grade to maintain a mini-
mum velocity of 2 fps. For a small-diameter sewer transporting effluent from
septic tanks, the minimum velocity can be 1.5 fps which reduces the maximum
depth of cut to 16 feet. The costs of pressure sewers with septic tank
effluent pumps shown in Figures IV-A-4-5 and 4-6 are fairly close to each
other for Scenarios 1, 2, 3, 4, 5, 6, and 7; only Scenario 8 is significantly
higher. In comparison to conventional gravity and small-diameter gravity
sewers, the pressure sewers with septic tank pumps are highly competitive
under Scenarios 2, 4, and 5 for all housing densities and for both 0 and 50%
rates of growth. By using septic tanks' pump pressure sewers, cost savings
are in the range of $1,300 to $17,000 per house. The higher cost differences
occur in the lower density range (i.e., 25 to 50 houses/mile), whereas lower
cost differences occur in the higher density range (i.e., 75 to 100 houses/
mile). However, pressure sewers with STEP pumps are expensive when compared
to conventional gravity sewers for Scenarios 1 and 3. The use of conventional
gravity sewers could result in cost savings in the range of $1,000 to $3,000
per house. The cost of pressure sewers with grinder pumps shown in Figures
IV-A-4-7 and 4-8 are comparable to the cost of pressure sewers with septic
tank pumps. The cost of Scenarios 1, 2, 3, 4, 5, 6, and 7 are fairly close to
each other and only Scenario 8 is significantly higher. The costs of grinder
pump pressure sewers are higher than septic tank effluent pump pressure sewers
by $250 to $350 per house for scenarios without growth, (i.e., with 0%
growth).
Per house present worth costs of coventional and alternative collection
sewers decrease as growth rate changes from 0% to 50% for the 20-year planning
period. For conventional and small-diameter gravity sewers, this reduction in
IV-A-34
-------
household costs is largest in Scenarios 2, 4, 5, and 7, with estimated de-
creases of 31-33% for conventional gravity sewers and 27-33% for small-
diameter sewers. Per house present worth costs of septic tank pump and
grinder pump pressure sewers are relatively less sensitive to a change in
growth rate (0% to 50%), with household cost reductions of 20-28% and 10-23%,
respectively. Futhermore, the reductions in per house present worth costs of
pressure sewers are almost universally equal for each scenario. The one
exception is Scenario 8, which registers a 20-40% greater reduction in house-
hold present worth costs than reductions associated with Scenarios 1 through
7.
The general conclusions of collection systems in this cost variability
study are as follows:
• In areas where the average depth of cut for conventional gravity
sewers is 8 feet or the depth of cut is 8 feet and one pump station is
required, then conventional gravity sewers are less expensive than
alternative collection systems.
• In areas where the average depth of cut of conventional gravity sewers
is 16 feet, or where topography is flat, or where the groundwater
table is at a depth of about 6 feet and dewatering would be required
to install conventional gravity sewers, then pressure sewers with
septic tank pumps or grinder pumps are less expensive than conven-
tional gravity sewers.
• A change in the growth rate from 0 to 50% effectively reduces the
estimated household present worth costs of collection systems by 10%
to 33%. The low end of this range includes pressure sewers; the high
end includes conventional and small-diameter gravity sewers.
c. Collection Transmission and Centralized Treatment
The household total present worth costs for centralized off-site waste-
water management systems, under 0 and 50% growth rates for the 20-year plan-
ning period, are illustrated in Figures IV-A-4-9 through 4-16. These graphs
depict the household costs of collection/transmission/centralized treatment
systems as affected by environmental conditions, developmental conditions, and
various modes of collection. Collection methods in this analysis are the same
as those examined earlier: conventional gravity sewers, small-diameter
gravity sewers, pressure sewers with septic tank effluent pumps, and pressure
sewers with grinder pumps. Tabulated data supporting these technology graphs
are presented in Tables IV-A-4-6 through 4-9.
The hierarchy of technology curves for collection/transmission/
centralized treatment systems is identical to that for collection (only)
systems under both 0 and 50% rates of growth.
For centralized systems using conventional gravity collection sewers, per
house present worth costs are highest for Scenarios 2, 4, and 5 (see Figures
IV-A-4-9 and 4-10). Moderately high costs are associated with Scenarios 7 and
8. Household present worth costs are lowest for Scenarios 1, 3, and 6. Under
50 percent growth conditions, costs for the eight scenarios become slightly
more competitive yet remain in the same order of highest to lowest cost.
IV-A-35
-------
The substitution of small-diameter gravity sewers for conventional
gravity sewers has no effect upon the overall ranking of collection/
transmission/centralized treatment system costs by scenario under both 0% and
50% growth rates (see Figures IV-A-4-11 and 4-12). At low housing densities
(25 and 30 houses per mile), household present worth costs of systems using
small-diameter sewer collection components are slightly less than costs of
systems with conventional gravity components for all scenarios and under 0 and
50% growth conditions. At high housing densities, conventional gravity system
costs are slightly less than those of small-diameter gravity systems for all
scenarios except 4, 5, and 7. As stated in the discussion of collection
system results, these exceptions are attributed to different depths of cut
required in flat topography by the two gravity systems.
The array of technology curves for centralized systems using pressure
sewers with septic tank effluent pumps (Figures IV-A-4-15 and 4-16) is
identical to the array of collection technology curves in Figures IV-A-4-5 and
4-6) and Figures IV-A-4-7 and 4-8. Centralized off-site systems utilizing
pressure sewers with septic tank pumps are less expensive than systems
utilizing conventional gravity and small-diameter sewers for Scenarios 2, 4,
and 5 for all housing densities under both 0% and 50% growth rates. Costs of
centralized systems utilizing pressure sewers with grinder pumps are competi-
tive with systems using pressure sewers with septic tank pumps for all
scenarios under both growth rates.
The decrease in household present worth costs of centralized wastewater
collection/transmission/treatment systems, estimated to result from a change
in the growth rate (from 0% to 50%), ranges from 12% (pressure sewer systems)
to 44% (gravity sewer systems). Cost variability study conclusions for cen-
tralized collection/transmission/treatment systems are similar to those for
collection (only) technologies discussed earlier. The analysis of centralized
collection/transmission/treatment systems does conclude, however, that a
change in the growth rate from 0 to 50% reduces the estimated household pre-
sent worth costs by 12 to 44%. This is slightly larger than the decrease
noted for collection (only) technologies in a similar assessment.
d. Collection, Transmission and Land Application
Technology curves that illustrate the household present worth costs of
centralized off-site systems utilizing three different methods of land appli-
cation, as affected by density, environmental conditions and growth rate are
included in Figures IV-A-4-17 through 4-22. Backup cost data for these curves
are listed in Tables IV-A-4-10 through 4-12, which identify the different
collection technologies utilized by density in each centralized land appli-
cation system. Collection methods selected, including conventional gravity
sewers, small-diameter gravity sewers, septic tank pump pressure sewers, or
grinder pump pressure sewers, were those found to be most cost-effective based
upon consideration of environmental conditions, density and growth rate. The
three methods of treatment by land application that were evaluated in this
exercise include rapid infiltration, slow rate and overland flow.
The technology curves indicate that, under 0 and 50% growth rates, most
per house present worth costs of all land application systems are highest for
Scenario 8. In this scenario, bedrock depth is severely limiting with an
average of two feet. Site preparation costs of wastewater management facili-
IV-A-36
-------
ties under these conditions are extremely high. Present worth costs of waste-
water management systems involving land treatment under Scenario 8 become
competitive with system costs under Scenarios 2, 4, and 5 at a density of
approximately 100 houses per mile. Household present worth costs for all land
application systems are lowest for Scenario 1 under both 0 and 50% rates of
growth. Scenario 1 represents optimum sewer construction conditions with
minimum depth of cut requirements and problems associated with groundwater,
bedrock or soil stability. Examination of the land application technology
curves for both growth rates also indicates that per house land application
system costs under Scenario 1 are generally competitive with Scenario 3 at a
density of approximately 75 houses per mile. A change in collection tech-
nologies from conventional gravity to small-diameter gravity sewers, at this
density accounts for the trade-off. An exception is noted for wastewater
management systems involving rapid infiltration, where costs under these
scenarios are competitive at a density of 75 houses per mile. Costs of land
application systems under Scenarios 2, 4, 5, and 7 are all quite competitive
up to densities of approximately 50 houses per mile, where systems costs under
Scenario 7 become significantly lower through the high ends of the density
range. This reflects the fact that small-diameter gravity sewers (in the
collection component of the system) under Scenario 7 are more cost-effective
than pressure sewers with septic tank pumps, under Scenarios 2, 4, and 5 at
densities of 75 houses per mile or greater. Per house savings in present
worth costs, realized by use of small-diameter gravity sewers instead of
septic tank effluent pump pressure sewers, range from $500 to $600 under a 0%
growth rate, and $80 to $150 under a 50% growth rate.
As with other off-site wastewater management facilities, household pre-
sent worth costs of land application systems decrease as the rate of resi-
dential growth changes from 0 to 50% for the 20-year planning period. The
range of decrease in these costs is from 9 to 23%. Decreases in per house
costs of systems using the slow rate method are slightly less than those of
systems using either the rapid infiltration or overland flow treatment
methods.
In conclusion,
• Household present worth costs for centralized off-site systems with
land treatment are highest under environmental conditions which in-
clude an average depth to bedrock of 2 feet and which involve densi-
ties less than 100 houses per mile. These costs are lowest under
conditions where optimum sewer construction conditions exist.
• In most cases, conventional gravity collection technologies are cost-
effective components of land application systems only in segments with
moderate to high housing densities (75 to 150 houses per mile).
Small-diameter gravity sewers are usually competitive with septic tank
effluent pump pressure sewers at low to moderate densities (25 to 75
houses per mile) for all land application systems under both rates of
growth. In no instance were grinder pump pressure sewers cost-
competitive collection components.
IV-A-37
-------
e. Collection, Transmission and Cluster Systems
Per house present worth costs of off-site facilities utilizing cluster
systems as the method of treatment are illustrated in Figures IV-A-4-23
through 4-30. Cost data prepared in support of these technology curves are
presented in Tables IV-A-4-13 through 4-16. As with previously assessed
off-site systems, U.S. EPA has evaluated the effect of conventional and alter-
native collection technologies on the household present worth costs of these
small-scale wastewater management systems. It was determined in the cost
variability study that, under both 0 and 50% growth rates, small-scale systems
utilizing small-diameter gravity sewers and septic tank pump pressure sewers
were more cost-effective than systems using other modes of wastewater collec-
tion.
Present worth costs of cluster systems employing conventional and small-
diameter gravity sewers were highest for Scenarios 2, 4, 5, and 8. These
conditions involve excessive depths of sewer cut, dewatering along sewer
trenches, and extensive rock excavation. Lowest costs for approaches uti-
lizing gravity sewers were associated with Scenario 1. For cluster system
schemes including septic tank pump and grinder pump pressure sewers, highest
household present worth costs were associated with Scenario 8, in which depth
to bedrock is severely limiting (2 feet). Per house present worth costs of
cluster system approaches using septic tank effluent pump pressure sewers
under the remaining seven scenarios are extremely competitive, being within
$80-$300 of one another for all densities under 0% growth conditions and
within $50-$200 for all densities under 50% growth conditions. Costs
associated with grinder pump pressure sewers under the seven remaining
scenarios (0% growth conditions) are competitive within each of two groups:
Scenarios 4, 5, and 7 (flat topography) and Scenarios 1, 2, 3, and 6 (hilly
topography). Under a 50% growth, the remaining seven scenarios costs for
these pressure sewers become competitive within a range of $600.
Per house present worth costs for small-scale approaches involving the
use of cluster systems can be expected to decrease by approximately 10 to 30%
as the residential growth rate increases from 0 to 50%. Larger reductions in
household costs are observed in cluster systems utilizing conventional and
small-diameter gravity sewers under Scenarios 2, 4, and 5. Costs of systems
using pressure sewer technologies are less sensitive to a change in the growth
rate.
The cost variability study concludes that the hierarchy of costs of
off-site approaches involving the use of cluster systems is very similar to
the hierarchy of costs for collection technologies alone. Where shallow
bedrock conditions exist, costs of systems involving pressure sewers are
prohibitive under all housing densities. In flat topography, household pre-
sent worth costs of systems using gravity sewers are prohibitive.
f. On-Site Technologies
On-site technology present worth costs per house are illustrated in
Figures IV-A-4-31 through 4-36. Corresponding backup data are presented in
Tables IV-A-4-17 through 4-19. The on-site technology curves are linear
instead of curvilinear for all scenarios. This is attributed to the fact that
economies of scale, which are realized for off-site facilities as density
IV-A-38
-------
increases, are not realized for on-site systems. On-site costs per segment
are not density dependent. Per house present worth costs will increase, not
decrease, as the rate of residential growth increases. Again no economies of
scale are realized as segment densities increase over the 20-year planning
period. These economies are apparent, indeed are quite significant, for most
off-site technologies. However, from the technology graphs, on-site tech-
nologies involving 10%, 20%, and 50% replacement levels for existing on-lot
systems are significantly more cost-effective than most of the off-site
systems.
The graphs indicate that present worth costs per house increase as the
rate of on-site system replacement increases. The on-site technology curves
suggest that highest household costs are associated with Scenario 8. Again,
shallow depth to bedrock is the factor imparting high costs to on-site system
users. However, compared to off-site technologies considered in the same
scenario (8), on-site technologies are most cost-effective except at high
densities where replacement rates exceed 20%.
Lowest household present worth costs of on-site technologies are asso-
ciated with scenarios involving flat topography and an average depth to
groundwater of six feet (Scenarios 4 and 5). Efficient operation of on-site
systems may work, independent of these environmental conditions.
g. Scenario Graphs
The 80 scenario graphs show the same information as the technology
graphs. However, each scenario graph represents one set of conditions as
listed in Table IV-A-3 (p. IV-A-10) and depicts the per household costs of
various technologies as determined by the environmental condition(s). These
depictions, Figures IV-A-4-37 through IV-A-4-52, are referred to as scenario
curves. Table IV-A-4-1 (Index of Tech Scenario, etc.) lists the scenario
graphs included in this study and identifies cost tables supporting the
scenario graphs.
The summary objective of preparing scenario graphs in addition to tech-
nology graphs was to enhance the reader's ability to identify trade-offs
between technologies for any given environmental condition or set of condi-
tions. This information may be used by local wastewater management planning
officials in their early development of alternatives to be ultimately (late
Step 1) evaluated in a detailed cost-effectiveness analysis. Technology
graphs cannot serve this purpose adequately, as they only depict trade-offs
between scenarios.
The following discussion of scenario graph results is again organized by
wastewater management technology categories. Detailed review of the scenario
graphs affords definition of subtle relationships between technology costs for
the same scenario. The discussion identifies only the major trade-offs
between competing technologies and points of interest.
h. Collection Technologies (No Transmission or Treatment)
An inspection of scenario graphs for these technologies indicates that
optimum or near optimum sewer construction conditions (Scenarios 1 and 3)
favor conventional gravity and small-diameter gravity sewers for all housing
IV-A-39
-------
densities. Gravity sewers that are cost-effective under these optimum condi-
tions at 0% growth become even more cost-effective as the growth rate in-
creases to 50% over the 20-year planning period. When local officials con-
sider bedrock constraints (Scenarios 6 and 8), gravity sewers are cost-
effective only at densities above 25 houses per mile. Under both growth
rates, pressure sewers with septic tank effluent pumps and grinder pumps are
significantly more cost-effective than gravity sewers in circumstances involv-
ing flat or rough (16 feet average depth of cut) topography.
i. Collection Transmission and Centralized Treatment
Scenario graphs for technologies in this category are presented in
Figures IV-A-4-53 through 4-68. Observations made about scenario graphs for
collection technologies described above hold true for collection/transmission/
centralized treatment systems. The only difference between these two sets of
graphs is the incremental cost for wastewater transport and treatment. As
described in Section 2.g. of this study, these add-on costs range from $3,712
at the lowest end of the housing density range to $636 at the highest end of
that range.
j. Collection, Transmission and Land Application Systems
The scenario graphs for land application systems (Figures IV-A-4-69
through 4-84) indicate that per house present worth costs for land application
by all three methods (rapid infiltration, slow rate, and overland flow) are
lowest under Scenario 1 and highest under Scenario 8. The difference between
costs of systems constructed under the remaining scenarios is insignificant.
The graphs also indicate that land application systems using treatment by
rapid infiltration are more cost-effective than systems using either slow rate
or overland flow treatment, all housing densities considered. Slow rate
systems are the least cost-effective. At no housing density do three scenario
curves intersect, suggesting that trade-offs between land application systems
should not be expected. This assumes that users of these curves will make the
same density-by-density determination of optimum (i.e., cost-effective) col-
lection technologies as was made in this study (see Tables IV-A-4-10 through
4-12). If this determination is not made, there could be trade-offs.
k. Collection, Transmission and Cluster Systems
Observations based on scenario graphs for collection/transmission/cluster
system treatment (Figures IV-A-4-85 through 4-100) are identical to those made
of graphs for collection and collection/transmission/centralized treatment
systems. In many scenarios, cost increments attributed to wastewater trans-
port and treatment via cluster systems have neutralized or eliminated trade-
offs between technologies that were observed in the scenario graphs for col-
lection.
1. On-Site Systems
Scenario graphs for on-site technologies, which include 10%, 20%, and 50%
replacement levels for existing on-site systems, are presented in Figures
IV-A-4-101 through 4-116. With the exception of mixed on-site technologies
based on a replacement rate of 50% under Scenario 8, these graphs indicate
that topographic, groundwater and bedrock conditions have an insignificant
IV-A-40
-------
effect on the household present worth costs of on-site technologies (10%, 20%,
and 50% replacement). Costs for on-site technologies with a replacement level
of 10% range from $588 to $1,523 per house. These figures represent the
lowest on-site technology costs considered in this study. This range in-
creases from $1,205 to $2,328 per house under 20% growth conditions. Highest
on-site technology costs are represented by approaches involving 50% replace-
ment level. These costs range from $3,641 to $5,923 under no growth condi-
tions, and from $4,546 to $7,154 under 50% growth conditions. The increase in
per household costs between 0% and 50% growth is due to the use of the design
year's number of dwellings for calculating per household costs. 100% of the
cost of future on-site systems are included in the present worth estimate,
whereas only 10% to 50% of existing systems need replacement.
m. Cost-Effactive Options
This set of graphics synthesizes the most cost-effective technology
options that were apparent during analysis of the scenario graphs. The most
cost-effective technology category is highlighted as a "cost-effective option"
by scenario. In all scenarios, on-site technologies at 10% and 20% replace-
ment levels are the most cost-effective options available at densities ranging
from 25 to 150 houses per mile. Occasionally off-site facilities are competi-
tive with on-site technologies at 50% replacement levels. The following brief
discussion will identify those technologies that are competitive with on-site
systems.
Scenario 1. Communities with sufficient wastewater transport and treat-
ment capacity and who need only to construct new conventional or small-
diameter gravity collection lines may find their project to be competitive
with on-site systems @ 50% replacement at housing densities of approximately
50 homes per mile (under 0% growth condition). As the growth rate increases
to 50%, off-site facilities become more competitive vis-a-vis on-site systems.
Centralized collection/transmission/treatment systems are competitive with 50%
replacement on-site technologies in the vicinity of 90 houses/mile. With
growth conditions in effect, collection (only) technologies (gravity sewers)
become competitive with 20% replacement on-site systems. At high housing
densities, all centralized off-site facilities are competitive under Scenario
1 (see Figures IV-A-4-116 through 4-125).
Scenario 2. Under Scenario 2, average depth of cut requirements put off-
site systems out of competitive range with on-site technologies (see Figures
IV-A-4-117 and 4-126). Cost-effective collection modes include both septic
tank pump and grinder pump pressure sewers. A collection (only) system,
utilizing pressure sewers with septic tank pumps, is competitive with 50%
replacement on-site technologies at approximately 110-130 houses/mile at 50%
growth.
Scenario 3. Cost-effective options under this scenario (see Figures
IV-A-4-118 and 4-127) feature collection by gravity sewers. As in the pre-
vious two scenarios, off-site systems utilizing treatment by rapid infiltra-
tion and by cluster systems are not competitive. Collection (only) tech-
nologies achieve competition with 50% replacement on-site systems at densities
of approximately 70 houses/mile (no growth) and 50 house/mile (50% growth).
Competition with 20% replacement on-site technologies is achieved by collec-
tion (only) in the vicinity of 100 houses/mile.
IV-A-41
-------
Scenario 4. On-site technologies (all replacement levels) are clearly
the most cost-effective options in this scenario (see Figures IV-A-4-119 and
4-128). There are no developmental conditions under which off-site facilities
are competitive. Environmental factors mitigating against cost competition
here include flat topography and groundwater depths averaging six feet.
Scenario 5. Cost-effective options for Scenario 5 (see Figures
IV-A-4-120 and 4-129) are similar to those for Scenario 4 due to similar
physical conditions.
Scenario 6. Under no growth conditions, on-site technologies (all
replacement levels) are the most cost-effective options. At 50% growth, cen-
tralized collection (gravity)/transmission/treatment is competitive with 50%
replacement on-site technologies at around 115 houses per mile (see Figures
IV-A-4-121 and 4-130).
Scenario 7. Cost-effective options in this scenario include on-site
systems (at all densities) and collection only technologies in the vicinity of
80 houses/mile (no growth) and 70 houses/mile (with growth). See Figures
IV-A-4-122 and 4-131.
Scenario 8. Off-site facilities costs are significantly higher than
those for on-site facilities under no growth conditions. Gravity sewer col-
lection (only) facilities become competitive with 50% replacement on-site
technologies at approximately 80 houses/mile, when rock blasting is eco-
nomical. Under conditions of 50% growth, off-site system competitiveness
improves with competition achieved at densities of approximately 70-85
houses/mile for collectors only, 90-110 houses/mile for centralized treatment
and 115-150 houses/mile for cluster systems.
IV-A-42
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IV-A-49
-------
APPENDIX A
-------
TECHNOLOGY CURVES
Conventional Gravity Sewers
(No Transmission/Treatment)
0% Growth
20,000
18,000
16,000
o
•^
CO
cr
_
o
Q
UJ
O
CM
14,000
12,000
cr 10,000
o
i-
LLJ
co
uj 8,000
cr
a.
6,000
4,000
2,000
1 = Scenario 1
I
I
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
Figure IV-A-4-1.
Costs of conventional gravity sewers (no
transmission/treatment) for 8 scenarios;
0% growth.
-------
TECHNOLOGY CURVES
Conventional Gravity Sewers
(No Transmission/Treatment)
50% Growth
30,000
18,000
16,000
ID
o
x
^
V)
cr
12,000
o: 10,000
O
Ul
uj 8,000
IE
a.
LU
O 6,000
(M
4,000
2.OOO
1 = Scenario 1
I
I
38
75
113
150
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
FUTURE
PRESENT
Figure IV-A-4-2.
Costs of conventional gravity sewers (no
transmission/treatment) for 8 scenarios;
50% growth.
A-2
-------
ao.ooo
18,000
16,000
o
o
o
o
14,000
ie.000
10,000
u
CO
UJ 8,000
cc
0.
IT
u
CNJ
6,000
4,000
2,000
TECHNOLOGY CURVES
Small Diameter Gravity Sewers
with Septic Tanks (No Trans-
mission/Treatment)
0% Growth
1 = Scenario 1
I
I
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
Figure IV-A-4-3.
Costs of small diameter gravity sewers
with septic tanks (no transmission/
treatment for 8 scenarios; 0% growth.
A-3
-------
TECHNOLOGY CURVES
Small Diameter Gravity Sewers
with Septic Tanks (No Trans-
mission/Treatment)
50% Growth
20,000
18,000
16,000
o
X
v»
V)
O
14,000
12,000
tr 10,000
O
LU
£3 8,000
cr
a
LJ
si
6,000
4,000
2,000
1 = Scenario 1
I
38
75
113
150
FUTURE
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
PRESENT
Figure IV-A-4-4.
Costs of small diameter gravity sewers
with septic tanks (no transmission/
treatment) for 8 scenarios; 50% growth.
A-4
-------
TECHNOLOGY CURVES
Pressure Sewers with Septic
Tank Effluent Pumps (No
Transmission/Treatment)
0% Growth
20,000
18,000
16,000
O
•v
in
-------
TECHNOLOGY CURVES
Pressure Sewers with Septic
Tank Effluent Pumps (No
Transmission/Treatment)
50% Growth
30,000
18,000
16,000
O
O
Q
14,000
12,000
K. 10,000
O
z
W
UJ 8,000
a.
LU
csj
6,000
4,000
2,000
1 = Scenario 1
I
I
38
75
113
150
FUTURE
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
PRESENT
Figure IV-A-4-6.
Costs of pressure sewers with septic tank
effluent pumps (no transmission/treatment)
for 8 scenarios; 50% growth.
A-6
-------
TECHNOLOGY CURVES
Pressure Sewers with
Grinder Pumps (No Trans-
mission/Treatment)
0% Growth
20,000
18,000
16,000
o
V
V)
o:
14,000
12,000
tr 10,000
O
UJ
(rt
UJ 8.0OO
(£
Q.
<£
UJ
CJ
6,000
4,000
2,000
1 = Scenario 1
I
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
"Figure IV-A-4-7.
Costs of pressure sewers with grinder
pumps (no transmission/treatment) for
8 scenarios; 0% growth.
A-7
-------
TECHNOLOGY CURVES
Pressure Sewers with
Grinder Pumps (No Trans-
mission/Treatment)
50% Growth
20,000
18,000
16,000
14,000
en
o:
fj 12,000
O
o
-------
TECHNOLOGY CURVES
Conventional Gravity Sewers,
Transmission, and Treatment
0% Growth
20,000
18,000
16,000
o
v»
w
a:
o
o
O
14,000
12,000
10,000
ui
LJ 8,000
a.
CJ
6,000
4.000
2,000
1 = Scenario 1
I
I
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
Figure IV-A-4-9.
Costs of conventional gravity sewers, trans-
mission, and treatment for 8 scenarios;
0% growth.
A-9
-------
TECHNOLOGY CURVES
Conventional Gravity Sewers,
Transmission, and Treatment
50% Growth
20,000
18,000
16,000
O
"x,
V)
3
O
X.
O
14,000
12,000
10,000
UJ
ui 8,000
UJ
O
c\j
6000
4.00O
2,000
1 = Scenario 1
I
38
75
113
ISO
FUTURE
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
PRESENT
Figure IV-A-4-10. Costs of conventional gravity sewers, trans-
mission, and treatment for 8 scenarios;
50% growth.
A-10
-------
TECHNOLOGY CURVES
Small Diameter Gravity
Sewers with Septic Tanks,
Transmission, and Treatment
0% Growth
20,000
18,000
16,000
14,000
CO
-------
TECHNOLOGY CURVES
Small Diameter Gravity
Sewers with Septic Tanks,
Transmission, and Treatment
50% Growth
20,000
O
^
to
O
Q
o
18,000 (-
16,000 |-
14,000
12,000
10,000
z
UJ
UJ 8,000
er
o.
UJ
O 6,000
N
4.0OO
2,000
1 = Scenario 1
4,5,8
4,5,8
I
38
75
113
150
FUTURE
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
PRESENT
Figure IV-A-4-12.
Costs of small diameter gravity sewers with
septic tanks, transmission, and treatment
for 8 scenarios; 50% growth.
A-12
-------
TECHNOLOGY CURVES
Pressure Sewers with Septic
Tank Effluent Pumps, Trans-
mission, and Treatment
0% Growth
20,000
18,000
16,000
O
^
en
O
o
14,000
12,000
c: 10,000
o
V)
LJ 6,000
cr
a
UJ
C\J
6,000
4,000
2,000
1 = Scenario 1
I
I
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
Figure IV-A-4-13.
Costs of pressure sewers with septic
tank effluent pumps, transmission, and
treatment for 8 scenarios; 0% growth.
A-13
-------
TECHNOLOGY CURVES
Pressure Sewers with Septic
Tank Effluent Pumps, Trans-
mission, and Treatment
50% Growth
20,000
18,000
16,000
O
rf
a
14,000
12,000
CC 10,000
O
t-
LJ
UJ 8,000
tr
a.
cc
LJ
6,000
4,000
2,000
1 = Scenario 1
I
I
38
75
113
150
FUTURE
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
PRESENT
Figure IV-A-4-14.
Costs of pressure sewers with septic
tank effluent pumps, transmission, and
treatment for 8 scenarios; 50% growth.
A-14
-------
TECHNOLOGY CURVES
Pressure Sewers with
Grinder Pumps, Trans-
mission, and Treatment
0% Growth
20,000
18,000
16,000
O
V.
CO
cc
O
O
I
K
O
14,000
12,000
10,000
UJ
CO
uj 8,000
-------
TECHNOLOGY CURVES
Pressure Sewers with
Grinder Pumps, Trans-
mission, and Treatment
50% Growth
20,000
18,000
16,000
trt '4,000
o
V)
cc.
o
o
12,000
o: 10,000
O
H-
UJ
ui 8,000
cr
a.
LJ
6,000
4,000
2,000
1 = Scenario 1
_L
_L
_L
38
75
113
150
FUTURE
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
PRESENT
Figure IV-A-4-16.
Costs of pressure sewers with grinder pumps,
transmission, and treatment for 8 scenarios;
50% growth.
A-16
-------
TECHNOLOGY CURVES
Collection, Transmission,
and Land Application
@ Rapid Infiltration
0% Growth
30,000
o
18,000 -
16,000
to 14,000
CO
(T
O
£J
12,000
tr 10,000
o
LU
CO
LU 8,000
o:
CL
O 6,000
CJ
4,000
2,000
1 = Scenario 1
I
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
Fi-ure IV-A-4-17.
Costs of collection, transmission, and
land application @ rapid infiltration
for 8 scenarios; 0% growth. Collection
methods by density included in these
systems are identified in
Table IV-A-4-10 (Appendix pg. B-9;.
A-17
-------
TECHNOLOGY CURVES
Collection, Transmission,
and Land Application
@ Rapid Infiltration
50% Growth
20,000
18,000 -
16,000 -
14,000
Z3
O
X
a:
fj 12,000
O
Q
UJ
UJ
CC
Q.
UJ
10,000
8,000
6,000
4,000
2,000
1 = Scenario 1
I
I
38
75
113
150
FUTURE
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
PRESENT
Figure IV-A-4-18.
Costs of collection, transmission, and
land application @ rapid infiltration
for 8 scenarios; 50% growth. Collection
methods by density included in these
systems are identified in
Table IV-A-4-10 (Appendix pg, B-9).
-------
TECHNOLOGY CURVES
Collection, Transmission,
and Land Application
@ Slow Rate
0% Growth
20,000
18,000
16,000
to W.OOO
O
in
en
5 12,000
O
O
x
I-
-------
TECHNOLOGY CURVES
Collection, Transmission,
and Land Application
@ Slow Rate
50% Growth
20,000
18,000
16,000
o
I
V)
IT
O
O
14,000
12,000
£E 10,000
o
UJ
LJ 8,000
(E
o.
o:
ui
cj
6,000
4,000
2,000
1 = Scenario 1
2,4,5,8
I
I
38
75
113
150
FUTURE
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
PRESENT
Figure IV-A-4-20.
Costs of collection, transmission, and
land application @ slow rate for 8
scenarios; 50% growth. Collection methods
by density included in these systems are
identified in Table IV-A-4-11 (Appendix
PR. B-1D).
A-20
-------
20,000
18,000
16,000
o
•x
V)
tr
o
o
14,000
12,000
-------
TECHNOLOGY CURVES
Collection, Transmission,
and Land Application
@ Overland Flow
50% Growth
20,000
18,000
16,000
O
X
14,000
12,000
or 10,000
O
t-
LL)
id 8,000
tr
CL
CK
LU
C\4
6,000
4,000
2,000
1 = Scenario 1
2,4,5,8
I
38
75
113
150
FUTURE
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
PRESENT
Figure IV-A-4-22.
Costs of collection, transmission, and land
application @ overland flow for 8 scenarios;
50% growth. Collection methods by density
included in these systems are identified
in Table IV-A-4-12 (Appendix pg, B-ll).
A-22
-------
20,000
18,000
16,000
14,000
V)
cc.
o
o
12,000
-------
20,000
18,000
16,000
o
\
co
tc
O
O
O
14,000
12,000
10,000
UJ
LJ 8,000
1C
a.
LJ
6,000
4,000
2,000
TECHNOLOGY CURVES
Conventional Gravity Sewers,
Transmission, and Cluster
Treatment
50% Growth
1 = Scenario 1
I
I
38
75
113
150
FUTURE
25 50 75
HOUSES/MILE OF COLLECTOR SEWER
100
PRESENT
Figure IV-A-4-24. Costs of conventional gravity sewers,
transmission, and cluster treatment
for 8 scenarios; 50% growth.
A-24
-------
20,000
18,000
16,000
O
O
o
14,000
12,000
ir 10,000
o
LJ
|