EPA-600/2-77-017d
December 1977
Environmental Protection Technology Series
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EPA-600/2-77-017d
December 1977
SEWER SYSTEM EVALUATION, REHABILITATION
AND NEW CONSTRUCTION
A Manual of Practice
by
Richard H. Sullivan
Morris M. Cohn
Thomas J. Clark
William Thompson
John Zaffie
American Public Works Association
Chicago, Illinois 60637
Grant No. 803151
Project Officer
Anthony N. Tafuri
Storm and Combined Sewer Section
Wastewater Research Division
Municipal Environmental Research Laboratory (Cincinnati)
Edison, New Jersey 08817
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U.S. Environmental Protection Agency, 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 commerical products constitute endorsement or recommendation for use.
ii
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FOREWORD
The U.S. Environmental Protection Agency was created because of
increasing public and government concern about the dangers of pollution
to the health and welfare of the American people. Noxious air, foul
water, and spoiled land are tragic testimony to the deterioration of
our natural environment. The complexity of that environment and the
interplay between its components requires a concentrated and integrated
attack on the problem.
Research and development is that necessary first step in problem
solution and it involves defining the problem, measuring its impact, and
searching for solutions. The Municipal Environmental Research Laboratory
develops new and improved technology and systems for the prevention,
treatment, and management of wastewater and solid and hazardous waste
pollutant discharges from municipal and community sources, for the
preservation and treatment of public drinking water supplies, and to
minimize the adverse economic, social, health, and aesthetic effects
of pollution. This publication is one of the products of that research;
a most vital communications link between the researcher and the user
community.
Control of Infiltration/Inflow (I/I) has become a major early step
in reducing the amount of untreated or poorly treated discharges of
municipal sewage to receiving waters. This Manual of Practice has been
prepared to provide a ready reference for those concerned with identi-
fying and controlling I/I.
Francis T. Mayo
Director
Municipal Environmental Research
Laboratory
111
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ABSTRACT
This Manual of Practice has been prepared for use by local authorities
and consulting engineers for the investigation of sewer systems for infil-
tration/inflow. This Manual discusses three areas: sewer system evaluation,
sewer rehabilitation, and design of new systems to minimize infiltration/
inflow.
Procedures for conducting the System Analysis and Sewer System Evaluation
Study (SSES) are described in detail.
Sewer cleaning equipment and methods of sewer inspection are discussed in
detail. Factors which govern the cost of conducting work are given. Rehabili-
tation techniques are described and an analysis of factors to be considered for
each method described.
Establishment of infiltration limits for new construction is recommended
at a rate not to exceed 200 gal/in.-diam/mi/day (185.2 1/cm-diam/km/day).
Methods of testing are explained in detail.
This Manual of Practice was submitted in partial fulfillment of Grant No.
803151 by the American Public Works Association under the sponsorship of the
U.S. Environmental Protection Agency. Companion documents also submitted in
fulfillment of this project are EPA-600/2-77-017a, "Economic Analysis, Root
Control, and Backwater Flow Control As Related to Infiltration/Inflow Control,"
EPA-600/2-77-017b, " . . . ; Appendices," and EPA-600/2-77-017c, "Sewer Infil-
tration and Inflow Control Product and Equipment Guide." This manual covers
a period from July, 1974 to August, 1976 and work was completed as of May,
1977.
iv
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CONTENTS
Foreword ..... iii
Abstract ... ....... iv
Figures viii
Tables ix
Exhibits ix
Acknowledgements x
Section I Technical Procedures for Infiltration/Inflow Analy-
ses and Sewer System Evaluation Survey
Introduction . 1
Collection of Basic Data 2
Development of Mapping Data 5
Monitoring and Gauging of Sewer System
Flows 5
Field Investigations 6
Analysis of Survey Data 7
Drafting of the Analysis Report ...... 8
Sewer System Evaluation Survey 10
Physical Survey of System 11
Inflow Investigation 12
Preparatory Cleaning 13
Internal Inspection 13
Analysis of Data and Preparation of Cost-
Effective Analysis 14
Alternate Courses of Action to Implement Water
Pollution Control 18
Feasibility of Rehabilitation Coincident with
Evaluation Surveys .• 19
Explanatory Comments 20
Section II Guide to Cleaning, Inspection, Testing and Rehabili-
tation of Sewers 21
Sewer Line Cleaning 22
Cleaning Equipment and Methods 22
1. Rodding Machines and Accessory Tools . 23
2. Bucket Machines 24
3. High Velocity Water Machines 25
4. Hydraulically Propelled Devices ... 26
5. Debris Removal Devices 27
Cleaning Precautions . 27
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CONTENTS (Cont'd.)
Page
Difficulty and Cost Factors Which Affect
Cleaning Operations ..... 27
Sewer Line Inspection 28
Inspection Techniques 28
1. Television 29
2. Photographic 29
3. Manual/Physical Inspection 31
Footage Measurements ..... 33
Information to be Recorded ......... 33
Terminology 34
Difficulty and Cost Factors Which Affect
Inspection Operations 37
Sewer Line Testing 38
Testing Techniques for Lines In Service . . 39
1. Flow Measurement 39
2. Smoke Testing 39
3. Dye Testing 40
4. Chemical/Biological Testing 40
Difficulty and Cost Factors Which Affect
Testing Operations . . . . 40
Sewer System Rehabilitation 41
Deficiencies Considered for Rehabilitation . 41
Rehabilitation Techniques 42
Excavation and Replacement 42
Technique Advantages 43
Grouting 43
1. Acrylamide Gel 45
2. Urethane Foam 49
Grouting of Manually Accessible Pipe
52
Pipe Lining 53
1. Polyethylene 54
2. Glass Reinforced Polyester Mortar . . 55
3. Cement Mortar and Epoxy Mortar .... 56
Difficulty and Cost Factors Which Affect
Rehabilitation Operations 58
Root Control 59
Background Information 59
Effectiveness of Control 60
1. Mechanical Removal 62
2. Copper Sulfate 62
3. Herbicides 62
4. Scalding Water Flooding 65
Cost Data Development 66
Cleaning 66
Inspection 70
Smoke Testing 73
VI
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CONTENTS (Cont'd.)
Manhole Rehabilitation Costs ......
Sewer Line Grouting
Pine Lining (Polyethylene) °2
References . ..... 88
Section III Design Standards and Construction Methods for the
Control of Infiltration and Inflow in New Sewer
Systems 89
Predesign Investigations 89
Soil and Groundwater 89
Soils and Soil Classifications . 90
Design Allowance for Infiltration/Inflow . . 90
Gravity Sewer Pipe and Jointing Materials. . 101
Construction Methods and Inspection 109
Pipe Characteristics
Dewatering Techniques
Construction Leakage Allowances ...... 113
Obstruction Proof Testing 117
Deflection Testing of Flexible Sewer Pipe . . 117
Inspection of Construction ll8
Testing for Acceptance ..... 119
• Infiltration Testing 120
. Exfiltration Testing 120
Air Testing . . 121
Manhole Testing 122
Still Photography . , 122
TV Inspection, 122
Smoke Testing . '. 123
Visual Observations . 124
Conditions for Acceptance Tests . 124
Corrective Measures 125
Building Sewer Standards 125
Jurisdiction and Control 125
Codes, Construction and Testing . 126
References ? 127
Section IV Appendices
A. Description of Laboratory Test for Deter-
mination of Possible Inflow Through Man-
hole Cover Pickholes and Seat Surfaces . . 129
B. Sample Air Testing Specification 132
C. Sewer Leakage Test Guidelines i35
D. Patterned Interview Infiltration/Inflow
Analysis •
E. Manhole Inspection Check List .....
F. Standards for Selected Sewer Pipe and
179
Appurtenances -1-'
vxx
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FIGURES
Number
1 Steps for sewer system evaluation and rehabilita-
tion, flow chart 3
2 Cost-effective analysis 15
3 Internal grouting with hollow metal cylinder
flanked by inflatable rubber sleeves placed over
pipe joint 47
4 Sleeve packer for use with 3M Elastomeric grout . . 51
5 Application of cement mortar and epoxy mortar ... 57
6 Representative variations in root growth 61
7 Basic cleaning cost data 70
8 Internal pipe inspection cost data 72
9 Grouting cost per 300 ft (91 m) manhole section -
8-12 in. (20-30 cm) pipe vs. number of joints
grouted
10 Grouting cost per 300 ft (91 m) manhole section -
15-18 in. (38-45 cm) pipe vs. number of joints
grouted
11 Grouting cost per 300 ft (91 m) manhole section -
6 in. (15 cm) pipe vs. number of joints grouted .
12 Grouting cost per 300 ft (91 m) manhole section -
21-24 in. (53-61 cm) pipe vs. number of joints
grouted
13 Grouting cost per 300 ft (91 m) manhole section -
30-36 in. (76-91 cm) pipe vs. number of joints
grouted
14 Ratio of peak sewage flow to average flow ....
15 Intensity-duration-frequency rainfall curves . .
16 Stormwater allowance for design of separate
sewers
17 Typical asbestos cement sewer pipe joint ....
18 Clay pipe sewer joints
19 ABS pipe joint 105
20 Steel pipe sewer joint 1Q6
21 Precast concrete manhole 108
22 Typical TV camera with packer unit 123
23 Smoke testing blower set-up over manhole ..... 124
78
78
79
80
81
95
97
98
102
103
viii
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TABLES
Number Pag<
. 1 Cost Analysis Data . . 14
2 Chemicals Tested for Root Control 64
3 , Sewer Cleaning Difficulty/Cost Factors . 67
4 Inspection Difficulty/Cost Factors 71
5 Basic Manhole Rehabilitation Tasks and Cost
Relationship 76
6 Sewer Line Grouting Difficulty/Cost Factors .... 77
7 Pipe Lining Cost Variables 83
8 Pipe Lining Difficulty/Cost Factors 83
9 Typical Estimating Guide (Cost Elements) 84
10 Example Cost Summary 86
11 Design Flows for Sewers and Treatment Facilities . 92
EXHIBITS
1 Television Inspection Report 30
2 Television Sealing Report 46
ix
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ACKNOWLEDGEMENTS
This Manual was prepared by a Technical Advisory Committee (TAG) tp the
APWA project staff. The TAG was formed by invitation to key leaders in the
consulting engineering field and the sewer service industries. Mr. Leland
Gottstein, President of American Consulting Services, Minneapolis, Minnesota
was Chairman, and the three key subcommittee chairmen were: Thomas J. Clark,
Vice President, American Consulting Services, Minneapolis, Minnesota; William
Thompson, President and General Manager, Penetryn System, Inc., Winter Park,
Florida; and John A. Zaffle, Engineering Consultant, U.S. Concrete Pipe
Company, Cleveland, Ohio. The APWA Research Foundation expresses its thanks
to these gentlemen and the members of their subcommittees who devoted their
time to preparing the information.
The complete membership of the Committee was as follows:
TECHNICAL ADVISORY COMMITTEE
Leland E. Gottstein, P.E. (Chairman)
American Consulting Services
Minneapolis, Minnesota
Charles M. Aiken
Raymond International, Inc.
Houston, Texas
William J. Clarke
American Cyanamid Company
Wayne, New Jersey
Daniel Daley
Cues, Incorporated
Orlando, Florida
Robert H. Hedges
Rockwell International
Texarkana, Arkansas
Alvin I. Leff
Certain-Teed Products Corp.
Valley Forge, Pennsylvania
William J. Malcolm
Cherne Industrial, Inc.
Edina, Minnesota
Arthur T. Brokaw
Brokaw Engineering Associates
Princeton, New Jersey
Donald M. Cline
Pacific Clay Products
Santa Fe Springs, California
J. F. Evert
3M Company
St. Paul, Minnesota
Harold Kosova
Video Pipe Grouting, Inc.
Newfield, New Jersey
Tom Lenahan
Halliburton Services
Duncan, Oklahoma
Vincent Malveaux
Sewer Systems Evaluation, Inc.
Chicago, Illinois
x
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ACKNOWLEDGEMENTS (Cont'd.)
John Roberts
Armco Steel Corporation
Middletown, Ohio
Larry N. Spiller
American Consulting Engrs. Counc.il
Washington, B.C.
William B. Thompson
Penetryn System, Inc.
Winter Park, Florida
Harold Rudich
National Power Rodding Company
Chicago, Illinois
E. W. Spinzig, Jr.
Johns-Manville Sales Corporation
Denver, Colorado
John A. Zaffle
U.S. Concrete Pipe Company
Cleveland, Ohio
TAG EVALUATION SUB-COMMITTEE - I/I STUDY
Thomas J. Clark (Chairman)
American Consulting Services
Minneapolis, Minnesota
Leonard Anhalt
Graef Anhalt Schloemer
Milwaukee, Wisconsin
William Baker
Grant, Brundage, Becker & Stauffer
Columbus, Ohio
John G. Chalas
Metcalf & Eddy, Consulting Engrs.
Boston, Massachusetts
Michael A. Donnelly
DuFresne-Henry Engineering Corp.
North Springfield, Vermont
Frank Gianotti
Allen & Hoshall, Inc.
Memphis, Tennessee
Alberto F. Gutierrez
Gutierrez, Smouse, Wilmut & Assoc.
Dallas, Texas
Eugene Avery
American Consulting Services
Minneapolis, Minnesota
Richard Berry
Penetryn System, Inc.
Winter Park, Florida
Gerard F. Conklin
DuFresne-Henry Engineering Corp,
North Springfield, Vermont
R. B. Fernandez
Brokaw Engineering Associates
Princeton, New Jersey
Leland Gottstein
American Consulting Services
Minneapolis, Minnesota
Gordon W. Johnson
URS Research Company
Seattle, Washington
Robert G. Jones
Donohue & Associates, Inc.
Sheboygan, Wisconsin
Vincent Malveaux
Sewer Systems Evaluation, Inc.
Chicago, Illinois
Robert M. Krill
Department of Natural Resources
Madison, Wisconsin
W. H. Meadows
G. Reynolds Watkins, Cons. Engrs.
Lexington, Kentucky
xi
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ACKNOWLEDGEMENTS (Cont'd.)
E. Bruce Meier
Kirkham, Michael &
Omaha, Nebraska
Associates
Kenneth 0. Miller
Sanitary District of Rockford
Rockford, Illinois
James 0. Russell
Howard, Needles, Tammen & Bergendoff
Indianapolis, Indiana
William B. Thompson
Penetryn System, Inc.
Winter Park, Florida
Victor G. Wagner
Howard, Needles, Tammen & Bergendoff
Indianapolis, Indiana
Larry R. Wilms
Graef, Anhalt, Schloemer & Assoc.
Milwaukee, Wisconsin
Otto Milgram
Elson T. Killam Associates
Millburn, New Jersey
Robert R. Pfefferle
American Consulting Services
Minneapolis, Minnesota
Walter G. Shifrin
Consoer, Townsend & Associates
St. Louis, Missouri
Donald Vogt
Washington Suburban Sanitary Dist.
Hyattsville, Maryland
Robert R. Wallace
Robert R. Wallace & Associates
Hibbing, Minnesota
James H. Witt
Naylor Industries
Baton Rouge, Louisiana
TAG SEWER REHABILITATION SUB-COMMITTEE
William B. Thompson (Chairman)
Penetryn System, Inc.
Winter Park, Florida .
David J. Bucheck
3M Company
St. Paul, Minnesota
Gerard F. Conklin
DuFresne-Henry Engineering Corp.
North Springfield, Vermont
Daniel J. Daley
Cues, Incorporated
Orlando, Florida
Benjamin Fisco
Aquatech, Inc.
Cleveland, Ohio
William B. Jaques
W. G. Jaques Company
Des Moines, Iowa
William J. Clarke
American Cyanamid Company
Wayne, New Jersey
James T. Conklin
Penetryn System, Inc.
Winter Park, Florida
Michael A. Donnelly
DuFresne-Henry Engineering Corp,
North Springfield, Vermont
Leland E. Gottstein
American Consulting Services
Minneapolis, Minnesota
Harold Kosova
Video Pipe Grouting
Newfield, New Jersey
XII
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ACKNOWLEDGEMENTS (Cont'd.)
W. K. Klein
Joseph T. Ryerson & Son, Inc.
Chicago, Illinois
Vincent Malveaux
Sewer Systems Evaluation, Inc.
Chicago, Illinois
James Monaghan
Gelco Grouting Service
Salem, Oregon
Milton Schneider
DuPont Industries
Wilmington, Delaware
James Witt
Naylor Industries
Baton Rouge, Louisiana
William J. Malcolm
Cherne Industrial, Inc.
Edina, Minnesota
Lonnie McCain
Cherne Industrial, Inc.
Edina, Minnesota
Roger Kc Nowell
American Cyanimid Company
Wayne, New Jersey
Donald Stolzman
Raymond International, Inc.
Houston,, Texas
TAG CONSTRUCTION SUB-COMMITTEE
John A. Zaffle
U.S. Concrete Pipe Company
Cleveland, Ohio
Leland E. Gottstein
American Consulting Services
Minneapolis, Minnesota
Alvin I. Leff
Certain-Teed Products Corporation
Valley Forge, Pennsylvania
John Roberts
Armco Steel .Corporation
Middletown, Ohio
Leland L. Sphar
Pacific Northwest Concrete
Pipe Association
Seattle, Washington
W. J. Horsley
Inter-Pace .Corporation
Los Angeles, California
William J. Malcolm
Cherne Industrial, Inc.
Edina, Minnesota
E. W. Spinzig
Johns-Manville Sales Corporation
Denver, Colorado
Joe A. .Willett
American Concrete Pipe Association
Arlington, Virginia
xiii
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ACKNOWLEDGEMENTS (Cont'd.)
STEERING COMMITTEE
Member
Dr. Shanka Banerji
Associate Professor of
Civil Engineering
University of Missouri-Columbia
Stuart H. Brehm, Jr.
Executive Director
Sewerage & Water Board
of New Orleans
Leland E. Gottstein
President
American Consulting Services
A. E. Holcomb
Manager, Wastewater Collection Div.
City of Dallas, Texas
Shelley F. Jones
Director of Public Works
Ventura, California
James M. MacBride
Manager of Regional Operations
City of Winnipeg, Manitoba
Representing
American Society of Civil Engineers
APWA Institute for Water Resources
Technical Advisory Committee
Water Pollution Control Federation
APWA Institute for Water Resources
APWA Institute for Water Resources
xiv
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SECTION I
TECHNICAL PROCEDURES FOR INFILTRATION/INFLOW
ANALYSES AND SEWER SYSTEM EVALUATION SURVEY
INTRODUCTION
The basis of this manual was contributed by a Technical Advisory
Committee (TAG) formed by the American Public Works Association, from
among leading engineers, manufacturers' representatives and service
company representatives who expressed interest in contributing their
services« The TAG formed three subcommittees, each of which was enlarged
to more broadly represent the field of interest, i.e., analysis and
investigation, sewer inspection, cleaning and rehabilitation and new
construction.
The procedures and practices reviewed in this Manual of Practice
are not a "one time" panacea to sewer system problems„ A sewer system
cannot be rehabilitated on a one time basis and be expected to not
develop additional points of infiltration or inflow,, Rather, a regular
preventive maintenance program should be initiated in order that a mini-
mum of extraneous water flows can be maintained. In addition, because
of the multiple factors involved, absolute certainty of cause, effect
and cure cannot be assured,,
Throughout this Manual the definitions of Infiltration and Inflow
must be kept in mind. The effect of each upon the sewer system, treat-
ment facility, and the means of determining the extent of contributing
flow vary» In some rare cases, such as footing drains inflow may
resemble infiltration, but this is not a general case.
For purposes of this manual the terms are defined as follows:
"INFILTRATION" - the volume of groundwater entering sewers and
building sewer connections from the soil, through defective joints,
broken or cracked pipe, improper connections, manhole walls, etc.
"INFLOW" - the volume of any kinds of water discharged into sewer
lines from such sources as roof leaders, cellar and yard area drains,
foundation drains, commercial and industrial so-called "clean water"
discharges, drains from springs and swampy areas, etc. It does not
include and is distinguished from, "infiltration."
-------
"INFILTRATION/INFLOW" (I/I) - the volume of both infiltration
water and inflow water found in existing sewer systems, where the indis-
tinguishability of the two components of extraneuous waters makes it
impossible to ascertain the amounts of both or either.
The procedures involved in conducting an analysis of I/I conditions
in sewer systems to meet the requirements of PL 92-500 and amendments
thereto, and to conform with USEPA Rules and Regulations, can be listed
as an orderly sequence of tasks. These step-by-step actions are designed
to explore the scope and details of the problem and to ascertain the need
for, and techniques required, to subsequently evaluate causes, effects ,and
corrective actions.
The analytical tasks must be planned and executed to comply with
Paragraph 35.927, Subpart B, of the Rules and Regulations: information
submitted to the Regional Administrator should be the minimum necessary to
enable a judgement as to the possible existence of excessive I/I or absence
of excessive intrusion in the sewer system under study. If during the
conduct of the analysis study, the engineer finds that sufficient information
has been gathered to justify a judgement as to the possible existence or of
excessive absence of I/I, a report should be submitted for concurrence (by
the appropriate regulatory officials) at that time. The steps are
graphically shown on Figure 1.
In the case of obviously non-excessive I/I conditions, where treatment
plant flow data can be verified as accurate, and where the sewer system
tributary to the treatment plant is not subject to excessive I/I problems,
the full sequence of the listed analyses tasks need not be performed.
There are times when Section 35.927, Subpart A, would recognize the
validity of decisions about excessive or non-excessive I/I conditions based
on factors other than definitive cost-effectiveness. Such other factors
could include treatment works construction delays and consequent cost
escalation; water pollution conditions which require prompt alleviation;
local public health emergencies within the sewer system or related thereto;
the effects of plant and sewer system bypassing or overloading; and other
relevant economic or environmental factors. If these conditions are present
in sufficient magnitude, a rigorous economic analysis of alternatives may not
be needed before a decision can be reached on a possible excessive I/I
problem. Each case may be affected by its own indigenous conditions; each
case may influence its own course of action.
The six procedural steps involved in a comprehensive analysis of sewer
system I/I follow. The sequence and inclusiveness of the procedures may be
adjusted as necessary to arrive at required findings and conclusions on
completion of the analysis work.
Step 1; Collection of Basic Data
Analysis of I/I conditions in a sewer system must be based on a level of
data accumulation appropriate to the analysis phase. If the system is shown
to be possibly excessive, more detailed study will be done in the Sewer
System Evaluation Study (SSES).
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Included in
5 percent
Step 1
Federal
Grant
or
In 100 percent
funded 208
Program
•MMHM
INFIL
PATTE
SANIT;
SYSTEI
DRYV
DET
PRELIR
SEL
DETER
EXC
ESTAB
ANC
I NON-EXCESSIVE
INFILTRATION/INFLOW
STATE CERTIFICATION
INFILTRATION/INFLOW ANALYSIS
SANITARY AND STORM SEWER MAP STUDY
SYSTEM FLOW DIAGRAMS
DRY VS WET WEATHER FLOW
DETERMINATIONS
PRELIMINARY FIELD SURVEY AND
SELECTIVE FLOW TESTS
DETERMINATION OF EXCESSIVE OR NON-
EXCESSIVE INFILTRATION/INFLOW
ESTABLISH A PLAN OF ACTION, BUDGET,
AND TIMETABLE FOR EXECUTION
POSSIBLE EXCESSIVE
INFILTRATION/INFLOW
1 EPA REGIONAL ADMINISTRATOR |
Step 2
Included in Step
3 grant with the
plant
(Nl
DT elidible for 208
Program.)
ie 201
I
SEWER SYSTEM
EVALUATION SURVEY
PHYSICAL SURVEY
RAINFALL SIMULATION
PREPARATORY CLEANING
TELEVISION INSPECTION
ANALYSIS
1 NON-EXCESSIVE 1 1 EXCESSIVE B
INFILTRATION/INFLOW 1 [INFILTRATION/INFLOW 1
I EPA REGIONAL ADMINISTRATOR 1
EXPAND
TREATMENT
WORKS
1 .
1 SEWER SYSTEM |
I REHABILITATION 1
Figure 1. Steps for sewer system evaluation and rehabilitation, flow chart.
Source: State of Wisconsin Department of Natural Resources
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Much of the basic data required to guide the study can be obtained from
local sources if effective use is made of a carefully patterned and
executed interview program. The people who have "lived with" the sewer
system know its characteristics, components, capabilities and bottlenecks.
They know from experience as public officials or as local residents where
many defects are located, where hidden interconnections exist, what the
history of performance has been, what community planning and growth needs
have been and will be. They know many points of inflow, both permitted and
surreptitious, and official code requirements for plumbing and sewer
connec.ions.
This information will go untapped if an interview program is not carried
out. A fact-finding program will not yield full results if it is not carried
out with judgement, discretion and diplomacy. The interviews must "dig" for
facts with courtesy and care, but, nonetheless, with an inquisitive approach.
Interviews must be patterned to contact sewer, public works and engineering
personnel, covering officials and on-the-line maintenance and operation crews;
treatment plant staffs; health officials; plumbing and building inspectors; •
planning boards; water system officials; chambers of commerce, and others.
The collation, interpretation and verification of interview data are as
important as the gathering of facts.
Appendix D is a questionnaire for patterned interviews used by a
consulting engineering firm and is shown as an example only. The data
obtained by patterned interviews and from all other sources must include,
but not necessarily be limited, to the following:
1. Current population distribution data, both total and sewered, and
growth factors if needed for the study.
2. Geographical, climatological, geological topographical and
hydrological data.
3. Known physical condition of the sewer system, manholes and all
appurtenances.
4. Age, length, materials, sizes and depths of sewers.
5. Maintenance practices, problems and system failures.
6. Treatment plant flow records and charts.
7. Pumping station and lift station flow records.
8. Water consumption and use data. It is important to distinquish
between water consumption and water use. Consumption is the total
water produced or pumped into the distribution system. Water use
is the total water used by the customers. For customer metered
services it is the total metered water. The difference is called
unaccounted and consists of leakage, water used for fire fighting
from hydrants etc., and may amount to 25-35 percent of the
consumption.
9« Location of bypasses and overflows and their operating experiences
and records.
10. Sewer system problem areas, including manhole surcharging, over-
flow, street flooding, basement backups, etc.
11. Existing ordinances governing inflow connections to sewers and
enforcement programs and policies, as well as estimates of the
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extent and significance of such inflow connections.
12. All available sanitary, storm and combined sewer system maps,
plotted to workable scale or requiring such adaptation.
13. Ground water levels for all seasons, with correlation to rainfall
and snow melt conditions.
14. Quality of local receiving waters and required effluent or water
quality standards.
Step 2; Development of Mapping Data
No system can be analyzed until all of the sewer lines and appurtenant
structures are recorded on authenticated maps. Without such basic records
all of the underground facilities would be subject to blind exploration.
Mapping tasks include:
A. Updating or preparation of maps
1. Augmentation of existing maps with details of new
construction and revisions. .
-2. Preparation of new maps from as-built records,
additional underground surveys and other data.
3. Sewer maps, as a minimum, should be drawn to scale
and should indicate sewer sizes, direction of flow,
manhole locations, as well as other major sewerage
system elements: e.g., pumping stations, treatment
plant, bypasses, points of overflow, etc.
B. Division of system into sub-basins
1. Establishment of rational major sub-basins, based on
system layout, drainage areas, main sewers and tributary
lines, system configurations and other local factors
and system conditions.
2. Determination of small sub-sections when and where they
are required to cover more detailed study of I/I
conditions in specific parts of any sub-basin.
C. Preparation of sewer system flow diagrams and flow sheets.
D. Selection of key junction manholes for monitoring and gaging
flows at points in each sub-basin which will reflect I/I
conditions in constituent parts of the sewer system; choice
of key manholes must be based on a critical examination of
the system and the experience of local officials and the
investigator.
Step 3: Monitoring and Gauging of Sewer System Flows
Dependable monitoring of flows at properly chosen junction manhole
points is essential. Monitoring must be carried out at diurnal times
when the data can allow differentiation between normal expected sanitary
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flows and infiltration and inflow volumes. Use should be made of existing
sewer flow records at such central points as treatment plants and inter-
mediate pumping or lift station wet-wells pr wastewater handling equipment.
Flow monitoring should be done where this mode of data gathering is
required to obtain the necessary information to produce an adequate I/I
analysis study. There will be times and places, however, when flow
monitoring could be meaningless and expensive and should not be done because
other means can adequately describe the problem.
For example, if a particular sewer system is subject to manhole over-
topping, surcharged sewers, backed-up basements in such a manner that it is
determinable, without question, that I/I is the problem, flow monitoring
would be meaningless in the determination of excessiveness The answer to
the question, "Is this portion of the sewer system excessive?" is apparent
and flow in monitoring would not accomplish anything more. In addition,
under the circumstances described, the accuracy of any flow monitoring that
would be done would be highly questionable since depth of flow measurements
are the prime means of manhole monitoring at this time.
The monitoring tasks include the following:
A. Verifying flows from plant records, pumping or lift station charts
or log sheets, or from previous sewer gauging findings at the same
or nearby locations involved in the current analytical procedure.
B. Gauging flows at key junction manholes, pumping stations and
overflow points during hours of minimal flow, to determine the
presence and amounts of infiltration volumes in various sub-
sections of the sewer network. Gauging should be conducted at
times when groundwater conditions are such that infiltration
can occur and where such flow monitoring is necessary to
determine possible excessive infiltration.
C. Determination of daily and hourly flow variations in a limited
number of locations for the purpose of monitoring the
rainfall on the flow characteristics in various sub-systems and
to ascertain the quantity of I/I and differentiate be-
tween the two components.
Step 4: Field Investigations
All sewer analyses should include field investigative procedures that
will augment data on the system obtained from maps, metering and gauging
records and actual experiences and observations reported by interviews,,
Actual field investigations by a trained analyst will convert records into
the realities of the sewer system being studied. The investigative tasks
should include, but need not be limited to, the following goals:
A. Obtaining additional information on the physical condition of,
and flow characteristics in, the sewer system under study, such
as:
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1. Location, number and function of bypasses and overflows.
2. Flow conditions in key manholes under varying conditions,
with all manholes key-designated and described as to location.
3. Location, number and flow conditions of lift or pumping
stations.
4. Treatment plant flow sheets, process configurations and
metering equipment accuracies, including any flow diversions'
during peak flow periods.
5. Groundwater level gauging installations, to locate areas
which are subjected to high groundwater conditions at
all times or during certain seasonal periods.
B. Determination of types and sources of I/I by means of:
1. Limited surface and manhole inspections to ascertain the ,
existence of possible inflow sources on private property,
storm sewer arid sanitary sewer juxtapositions, and inflow
sources which may be found in the areas adjacent to, or in
close proximity to, such locations.
2. Other field diagnostic techniques, such as limited smoke
testing or flooding of selected storm sewers in close
proximity to sanitary sewers to determine suspected cross
connections or flow transference of flows into sanitary
lines, etc., whenever deemed necessary.
Step 5; Analysis of Data
The data developed during the analysis procedures must be interpreted
to ultimately determine whether the I/I problem in the community is
possibly excessive or non-excessive. In order to do this, the analysis of
the survey data should include the following tasks:
A. Determination of the base I/I quantities and maximum flow rates
in the system and key portions thereof.
B. Computation of treatment and sewage conveyance costs including
capital charges and operation and maintenance expenses for both
full and partial accommodation of I/I quantities. The partial
accommodation should be for the estimated flows remaining after
the cost effective rehabilitation.
C. Computation of estimated costs of system Rehabilitation, covering
forecasted cost effective I/I reduction.
D. Establishment of a basic plan for conducting a sewer system
evaluation survey coupled with the estimated costs of same for use
in a cost-effective analysis and to serve as a basis for funding.
E. Preparation of cost-effective analysis for I/I control,
comparing reasonable alternatives of treatment and trans-
portation of major or minor parts of the intrusion volumes
and the cost of system rehabilitation, repair or reconstruction.
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Step 6; Drafting of the Analysis Report
This task will require the drafting of findings and conclusions on
the presence of possible excessive I/I or the absence of this condition.
A. If non-excessive I/I conditions are found, the report must
present the volume of existing intruded waters experienced
in the sewer system that should be included in the design flows
of the treatment facilities.
B. If possible excessive I/I is found, the report must recommend
the performance of an evaluation survey, outline the plan of
action and estimate the cost of the SSES.
The sequential tasks outlined above for the Collection of Basic Data,
Development of Mapping Data, Monitoring and Gauging of Sewer System Flows,
Field Investigations, Analysis of Data, and Drafting of the Analysis
Report are intended as guidelines for the consummation of the I/I
analysis. They represent a generalized approach to the engineering problem.
The sequence of functions can be modified to meet local conditions and needs
and inclusion of all steps may be varied as the analytical procedures are
followed. The following commentaries will be of value in interpreting the
specific tasks and in determining the actual analysis procedures .
o Population records and future projections may be subject to
unavoidable discrepancies because of their relatively subjective nature.
In many overall metropolitan areas, growth projections can be made on a
fairly accurate basis but assignment of these regional growth forecasts
to individual treatment plant service areas may prove to be considerably
less reliable.
o Treatment plant flow data obtained as part of the data collection
process and of the monitoring and gauging functions may not fully reflect
actual flow conditions in the sewer system,, The accuracy of existing flow
metering equipment should be verified to provide validity of the records
used in the analysis. Field reconnaisance observations should be used to
determine if the sewer system is actually performing in conformity with
pumping station and treatment plant flow records„ The effect of bypassing
and overflows during dry-weather and wet-weather conditions as well as in-
system and off-system flow detentions must be factored into the flow records
to make analysis decisions more valid.
o Sub-divisions of the sewer system plot map into minor basins for
flow monitoring purposes should be made initially in terms of the large or
major system division areas. Then, if further and more detailed field
monitoring of flow gauging at additional key manholes are necessary to
analyze I/I conditions, such key points must be designated. In choosing
sub-basin points, consideration should be given to areas representing
homogeneous sewer system land-use and runoff characteristics. Use can
be made of community base records or information established for other
purposes if they can aid in establishing rational sub-section areas. Such
existing information may include data on population, dwelling units, water
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consumption by districts, and other factors which can be collated into the
I/I study.
o It is possible that, at the completion of the data collection
step and the development of mapping data actions, sufficient information
will be available to warrant a conclusion that the sewer system under
analysis does not have an excessive I/I problem. If this can be verified
at that time, the Regional Administrator of USEPA—and involved state
agency officials—should be asked to review the report and to reach a
decision on this finding without further work being performed.
o Flow monitoring must be performed as part of the analysis pro-
cedures when adequate base system flow information is not available, where
the minimal information required to determine treatment and transportation
costs will require this operation and where the scope of the evaluation
survey must be determined on the basis of known and verified flow data.
Flow measurements represent an estimate only, the accuracy of which is
controlled by the method used and the representativeness of the flow at the
time of measurement.
o Where physical evidence of sewer surcharge conditions, bypassing
or overflowing from the system is found to affect the actual flow conditions
in certain areas of the sewer network, this may preclude flow monitoring in
such areas. Where relief sewers or other system regulatory devices must be
installed as alternatives to system rehabilitation in order to abate sewer
surcharge problems, flow monitoring may be needed to design such physical
facilities and ascertain their cost.
o Field investigation procedures must be varied to meet actual
system needs and local conditions. The step-by-step procedures need not
be carried out simultaneously or sequentially as listed. Field work must
be planned and executed to meet two major objectives: The first is to
determine probable sources of I/I; the second is to supplement information
obtained through patterned interviews in the data-gathering phase of the
analysis and to verify such information. The results of a field investi-
gation can be useful in establishing future rehabilitation methods and
costs and in determining the plan of action when the Sewer System Evaluation
Survey (SSES) is undertaken. Both objectives provide needed elements of
the cost-effective analysis procedure. In any event, field investigations
should be limited to the facts needed to fill all information gaps which
exist.
o The data analysis phase of the analysis procedure, including
cost-effective analysis work and examination of treatment, transportation,
sewer system evaluation and rehabilitation alternatives, should be
performed only after the engineer feels that sufficient information is
at hand upon which to base analytical decisions„ He must be able to
justify his determinations with regard to the size and character of the
I/I problem, the scope and cost of any recommended evaluation survey,
estimates of possible rehabilitation costs, and finally, findings on
whether the system is subject to excessive or non-excessive I/I condition;:,
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o Other factors, either in addition to or in lieu of, a full
cost-effective analysis, may determine whether a system is subject to
excessive or non-excessive infiltration. Public health hazards, system
physical capacity constraints which create manhole surcharges, basement
backups, street flooding or large-scale bypassing or overflowing—all
these conditions could be evidence that such a system is subject to
excessive flow intrusions.
o If it were possible that specific parameters relating to
percentage of I/I volumes in a sewer system, or some other form of
criteria could be used as a guide to characterization of I/I as excessive
or non-excessive, this would become a valuable general guide for consult-
ing engineers in sewer system analyses procedures,, This, however, is
not now feasible or practical,
o It is possible to perform a full cost-effective analysis in
almost every case on every system, but the question of whether money
should be spent as part of the analysis procedure for this purpose
must be considered. Since the final cost-effective analysis—as part^
of a SSES will be used to determine treatment plant design and to decide
on the amount and method of system rehabilitation, there may be justi-
fication in waiting until the time when system evaluation surveys have
disclosed all pertinent information before the cost of alternative
procedures is ascertained. At that time supportable cost data can be
provided by the consultant. General cost-effectiveness parameters are
difficult to set; howeve^ with care, assumed and predetermined cost-
effective parameters may be used for the analysis to determine if the
SSES is needed. It must be understood by all that the analysis will
result in estimates. Absolute certainty is neither feasible nor apt
to be cost-effective to obtain.
o Each analysis project should be planned and executed in
conformity with the size of the community, the type and complexity of
its sewer system, future community needs, treatment works requirements,
and other indigenous conditions. In preparing a proposal for the scope
of the investigation, it may be necessary in some cases to give oniy a
general outline of a possible program, and to determine each succeeding
stage on the basis of work already accomplished and the findings there-
from. Consultants should examine each system's situation carefully and
determine which approach is best suited to meet the client's needs. In
general, very large systems demand a flexible step-by-step approach
while very small systems may be planned on the basis of a firmly
established scope of work from the outset.
SEWER SYSTEM EVALUATION SURVEY (SSES)
The location of specific I/I sources in a sewer system is the
second phase of the investigative procedure,, It follows completion of
the analysis stage and the recommendation of the analysis program. It is
intended to confirm the general overall findings of the analyses program
and to convert preliminary diagnoses into firm conclusions as to the
10
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presence of, location, and degree of I/I. It must also determine what I/I
intrusion is excessive or non-excessive in conformity with criteria
stated in PL 92-500 and USEPA rules and regulations. Definitive cost-
effectiveness studies supported by the actual findings of the evaluation
survey are used to estimate the amount of I/I which could be eliminated
as compared to the cost of expanded physical facilities.
This conversion of preliminary findings into positive evaluation
facts must be based on a detailed diagnosis of sewer system conditions.
Such detail augments and supplements the more generalized data obtained
during the analysis phase of an I/I study. Thus, the findings of the
SSES must dictate the nature of corrective actions, their costs, the
means by which I/I will be controlled, and the basis for treatment plant
capacity design decisions. The evaluation survey phase will determine
the extent of system rehabilitation, in a rational sequence. An
accomplishment factor must be considered inasmuch as the estimates of flow
which are identified as cost-effective to remain may not be 100 percent ,
accurate.
If the findings of the analysis stage clearly demonstrates that
excessive I/I does not exist in the system, and if this conclusion
receives the concurrence of state and Federal EPA agencies, the eval-
uation phase will not be undertaken.
The evaluation survey must be planned and carried out to produce
the type of authentic information that will justify the subsequent
conclusions and recommendations. The depth and dimension of system
evaluation must meet this criterion if it is to be the instrument for
determining the actual sources of I/I, the scope of the problem, the means
for correcting or alleviating it, the costs involved, and the determination
of the most cost-effective means for handling the problem in each specific
system. The following tasks will achieve the evaluation results required
under the terms of the law and the USEPA rules and regulations.
Physical Survey of System
The need for a physical survey of any sewer system under investigation
is obvious. The procedures listed below will establish a proper base for
the qualitative and quantitative studies that will follow and the decisions
which will translate evaluation findings into specific actions.
A. Above Ground Reconnaissance
1. Determine manhole access problems, such as easement, buried
.structures, traffic interference, etc.
2. Verify accuracy and completeness of sanitary sewer maps.
3. Determine proximity of storm and sanitary sewers if storm
sewer maps are not available.
4. Observe inflow sources, such as roof downspouts, yard and
area drains, creeks, low or inundated manhole covers and
frames, and foundation drains, etc.
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5. Plan for rainfall simulation tests in the form of smoke testing
and/or dyed-water flooding.
6. Establish a program for uncovering manholes, improving frames
and raising manholes to or above grade.
B. Manhole Inspection - see Appendix E
1. In sub-system selected key manholes, if necessary, take flow
line readings, primarily during early morning hours.
2. Descend and examine condition of all manholes and lamp all
lines which are required to ascertain sub-system I/I conditions.
3. Analyze data and recommend sewer sections for internal
inspection to locate groundwater infiltration sources
and amounts.
4. Record information on physical condition of lines and manholes
as noted during manhole inspection, or lamping, as well as
any I/I sources observed.
5. Determine preparatory cleaning methods and costs for those
lines chosen for internal inspection. A goal of this phase
of investigation should be to isolate the study area to only
those areas where I/I problems actually exist. Total costs
of manhole inspection, cleaning and such depend upon the size
of the area studies. Thus the need to accurately delineate
where problems exist.
Inflow Investigation
Infiltration caused by sewer system structure failures or defects
can be classed as "accidental„" These sources of infiltration are
difficult to locate and expensive to correct. Conversely, inflow sources
are often easier to detect and less costly to correct by structural means.
Such, interconnections or transferences can be located by such tasks as
smoke testing and artificial flooding of storm lines, creeks or other
sources of intrusion into sanitary lines. Key steps are as follows:
A. Smoke Testing
1. Conduct smoke tests in selected sanitary lines (public
notification is desirable before such programs are
initiated).
2. Record, both in written and photographic form, all sources
from which smoke emissions are noted.
3. Visually inspect manholes suspected as a result of smoke
testing, of having direct inflow connections into sanitary
sewers.
4, Identify and quantify direct inflow connections to sanitary
sewers.
50 Identify interconnections between sanitary and storm
system as evidenced by smoke emissions from the smoke test.
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B. Dyed-Water Flooding
10 Plug and flood with dyed water storm sewer sections which
are parallel to or cross sanitary sewers and house service
lines and which have shown evidence of smoke if nearby
sections have so been tested.
2. Where applicable, flood catch basins, ditches and ponding
areas in close proximity to sanitary sewers with dyed water.
3. Note sanitary flows, both before and after flooding, at
points upstream and downstream of flooded areas.
4. Analyze findings and recommend appropriate sewer sections
for cleaning and internal inspection.
Preparatory Cleaning
Internal inspection of lines suspected of having I/I sources requires
the existence of clean lines. Debris in sewer inverts, grease accumu-
lations on sewer barrels and heavy root infestations not only obstruct
visual or video inspection equipment but they may hide or mask actual
infiltration sources. Preparatory cleaning is an essential first step
in any meaningful internal examination procedure. The following steps
are required:
10 Clean by appropriate means and with proper equipment all
sewer lines immediately prior to internal inspection.
2. Determine, if possible, all obstructions or other physical
line, joint or connection conditions which could interfere
with or prevent the insertion and movement of inspection
equipment.
Internal Inspection
The human eye, or a camera in the form of internal inspection
equipment--are the means of inspecting sewer lines. Human eye techniques
are limited to manhole-to-manhole lamping in short, small diameter lines
and to direct observation in large lines that can be walked or crawled.
Camera inspection involves the following tasks:
1. Set up TV camera equipment or other equipment in the sewer
lines under investigation.
2. Plug and flood all storm sewers in close proximity to sanitary
sewers under inspection, if recommended by rainfall simulation
findings.
3. Internally inspect designated footage, noting all structural
defects and logging all leaks in terms of location and flow
rates.
4. If services are found to be running, verify whether the flow
is caused by infiltration or actual water usage.
5. Record findings on log sheets supported by photos or video tape.
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Analysis of Data and Preparation of Cost-Effective Analysis
The purpose of evaluation fact-finding is to evaluate the"I/I
problem and to arrive at a rational decision as to the most cost-effective
means of correcting or alleviating excessive intrusion conditions found.
in the system. It is the purpose of the following analysis-evaluative
procedures to translate investigation findings into specific recommen-
dations for positive action:
1. Assign quantitative I/I values to each source found during the
evaluation survey on the basis of measurement or judgement,,
2. Calculate- and assign costs of rehabilitation, repair or replace-
ment to each source of I/I based upon the costs in Section II
of this Manual or from local experiences.
3. List all structural defects found.
4- List all I/I deficiencies in cost-effective order—i.e., the
least costly in terms of cost versus the quantity of flow
eliminated by such corrective action, first followed in
sequence by succeeding cost vs; benefits actions. Table 1 is
an example of such a list.
8,
9.
TABLE 1. COST ANALYSIS DATA
Typical Headings fqr Columns
Street
From
To
Length (ft)
Size (in.)
Pipe Material
Sani tary/S torm
Type Repair
Cost/Repair
Cost/Clean & Insp.
GPM Before
GPM After
GPM Reduced
% Reduction
Cost/GPM Removed
Present Value ($/ft)
Date Installed
Notes
On an incremental basis, compare the capital and operation and
maintenance costs of transporting and treating flow from each
I/I source found and listed in Item 4 with the cost of rehabil-
itating that source. A curve or curves comparing these functions is
usually the preferable tool for accomplishing this cost-effective
analysis. Figure 2 is an example of such a curve.
Choose the most cost-effective combination of system rehabilitation
vs. treatment and transportation. Rehabilitation will only be done
on those I/I sources that cost less to repair than to transport and
treat.
Recommend the amount :of I/I to be eliminated from the system by
rehabilitation work and the amount that will remain in the system
to be transported and treated.
Specify the details of the designated cost-effective rehabilitation
program.
All costs included in the above analysis are expressed in present
worth over 20 years.
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2.0
= I-5
1.0
0.5
TOTAL
BASE PLANT SIZE:
12mgd design
24 mgd peak
BASE PLANT COST:
$15.7 million
Peak Infiltration/Inflow
SSES
COST
0 5 10 15 20 25 30
Peak Infiltration/Inflow Rate (mgd)
Figure 2. Cost effective analysis.
The sequential steps listed above for sewer system evaluation survey
purposes must be carried out whenever the analysis--Phase I--study
indicates the possibility that excessive I/I exists in the system under
investigation,, The procedures are required,by law and regulations to
allow preparation of viable conclusions and engineering recommendations
on the extent of rehabilitative work required, how much system corrective
action is needed, how rehabilitative work should be performed, the
probable cost thereof, and the benefits to be derived,, While the tasks
listed are essential, their inclusion in the evaluation plan and the
sequence in which they are carried out is subject to necessary flexibility
of decisions based on local conditions and sewer system factors. The
following comments are provided to help interpret the various tasks to
be done in a sewer system evaluation survey,,
o If the determination of possible excessive I/I during the
Phase I work--analysis stage—is made on the basis of incomplete or
inadequate flow data, the evaluation survey must upgrade these data to
acceptable levels. Additional flow monitoring will be required to meet
thi s need.
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o The evaluation survey is-generally thought of as being accom-
plished in five successive stages. The USEPA guidelines tend to recognize
that these stages may not have to be carried out separately or consecu-
tively. However, other interpretations of the guidelines indicate that
these stages or tasks and their sequential performance must be adhered
to without deviation,, It would be helpful if sewer system investigators
were allowed flexibility in accomplishing the program as long as the
evaluation procedures result in a meaningful and economical rehabili-
tation-corrective programo
o Internal inspection for locating infiltration conditions
should be justified by the findings of the physical survey. Internal
inspection for locating interconnections or transferences between storm
sewers and sanitary sewers should be justified by dyed water or smoke
tests before they are undertaken. Due to the time of commencement of
a sewer system study and prevailing groundwater level conditions, it
is possible that smoke testing or dyed-water flooding may precede the
physical survey. Groundwater and climatological conditions in the
survey area may make it necessary to carry out all phases of the evaluation
survey simultaneously or in varied sequence. However, all internal
inspection work must be justified by the findings of the pre-qualification
steps.
o One of the goals of an evaluation survey is to continuously
redefine the extent of the area where investigative and corrective actions
are needed. Even though a particular sub-basin or district has been
designated for study in the analysis survey each manhole in that district
may not have to be inspected. If the physical survey begins with the goal
of prequalifying those areas of a sewer system which are subject to high
groundxrater or if infiltration is isolated by flow monitoring techniques
and night flow readings, additional elimination of manholes to be covered
in the district may be possible. If the determination of possible
excessive I/I in the analysis phase was based on a minimal or an inadequate
amount of field work and monitoring, the evaluation survey must be adequate
enough to validate the overall findings and conclusions.
o Ultimately, all manholes in an area known to be subject to
infiltration should be descended, inspected, lamped and evaluated for
infiltration impacts. A cost-effective test should be applied to sewer
sections and areas to determine if television inspection should be performed.
The factors of manhole and sewer accessibility and line cleanliness should
be a major consideration in such a cost-effective test.
o The search for inflow sources should be approached in several ways.
Most 'such sources can be detected from above-ground observations and by
means of smoke tests and dyed-water flooding. A determination of sub-areas
containing significant amounts of inflow may be made by further flow
monitoring within the chosen study areas.
o At some point in the course of the monitoring of sub-districts, it
may become less expensive to locate sources of inflow by means of actual
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source location methods rather than to invest time and money in additional
flow gauging operations. The cost of information gained through additional
flow monitoring may exceed its value, if performed too extensively.
o Smoke testing should be carried out during periods of low ground-
water levels to preclude any interferences with smoke emissions due to the
water sealing of leaks, connections and interconnections by groundwater.
In areas Subject to constant high groundwater tables, dyed-water flooding
may be the only way to verify interconnections and flow transference between
storm sewers and sanitary lines.
o If a line has been designated for closed-circuit television
inspection for groundwater infiltration and it lies adjacent to or under
storm sewer sections suspected of being a possible contributor of intrusion
water, flooding of that storm sewer should take place during the internal
inspection. Flooding of the storm sewer prior to internal inspection may
prove to be an unnecessary procedure should the line have been already
designated for internal examination.
o In circumstances where the logistics can be worked out, and
prior approval is obtained, internal inspection may follow directly after
dyed-water flooding without the need for another additional flooding
setup. Scheduling of cleaning and internal inspection in a manner that
will expedite coverage of the sanitary system while the storm conduit is
still flooded offers opportunities for time-saving and economies,,
o Dyed-water flooding of ditches and ponding areas may not be
possible because of unavailability of city water. In such cases, areas
may be prepared for flooding tests prior to a rainstorm and testing
can be carried out for interconnections and transference during the
period of precipitation and runoff.
o Internal inspections should be carried out when the sewer
lines are relatively free of flow0 This may require upstream plugging
of lines or the scheduling of inspections during early morning hours„
Flow monitoring may be limited to carefully chosen periods when metering
of interceptor sewers which are never devoid of flows is undertaken.
The need for expensive internal inspection of such sewers should be
proven by flow gauging before the expense and trouble of dewatering or
physical inspection is undertaken.
o During the course of internal inspections, it is imperative
that running house services be verified,to ascertain whether observed
flows through such connections are due to infiltration, inflow or
legitimate water use. Such verification may be more time consuming
than routine structural inspection of sewer lines.
o The final cost-effective analysis at the end of an evaluation
survey may be accomplished through the use of several criteria curves—
one for inflow, one for infiltration—because of the difference in
duration of water intrusion phenomena from these two sources. Under
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other circumstances the analysis may also be carried out with a single
curve which can portray the impact of the infiltration component and
the inflow component when developing the treatment and transportation
curve. The solution of the cost-effective problem will require variable
approaches to meet variations in sewer conditions, treatment plant
loadings and other local variables,
o A follow-up program, possibly as a part of the rehabilitation
procedures or contract, should be required in order to assess the actual
results of sewer system sealing, relining, repairs or reconstruction„
Rehabilitative work cannot be considered successful unless the control
of infiltration is effective over an extended period of time,
o A sewer system rehabilitation program should stimulate contin-
uous preventive maintenance programs, ra-ther than giving a false sense
of security and lulling operations crews into spasmodic service and
inspection schedules„ Communities cannot expect that new infiltration
points will not continue to occur, or that inflow connections will not
be made either illicitly or with the knowledge of some governmental
agencye Every I/I study should be augmented with an operation and
maintenance manual, prepared as part of the rehabilitation program0
Alternate Courses of Action to Implement Water Pollution Control
USEPA rules and regulations allow alternatives to standard facility
planning and I/I evaluation procedures„ They are listed as "exceptions"
in the regulation system; they are, however, more aptly described as
"alternativese" Ideally, long-range planning on the part of state
regulatory agencies with regard to the formulation of priority lists and
funding programs should allow Step I planning processes to proceed far
enough in advance so that by the time a required treatment works is at
the construction funding stage this planning work will have been
completed,, This would allow for an orderly progression of planning,
design, funding and construction, and overcome impedences in the water
pollution control program.
Such long-range plans have not been in effect long enough to fully
implement such an orderly procedure. As a result, many projects reach
the construction funding stage before the completion of the total
planning process, part of which is involved with I/I evaluation surveys„
USEPA regulations— Paragraph 35.927-5, Subpart C--contains an
alternative procedure in the form of modular construction of treatment
works projects. In order to qualify under this provision in the law, it
must be shown that the treatment facility for which a grant application
is made will not be significantly changed by an subsequent sewer system
rehabilitation program and that I/I remaining in the sewer system can
be accommodated by future plant enlargement by means of modular additions
to the basic design capacity. If this is done, sewer system evaluation
can proceed concurrently with plant design.
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Unfortunately, modular construction is not applicable in all cases.
It may be especially applicable to large communities or to areas which
will experience marked population growth in the near future. In
communities where little or no growth is expected, treatment plants must
be designed for specific flows to meet ultimate needs during the design
life of the project and there may be no alternative to the procedure of
withholding design decisions until the evaluation and rehabilitation
stages of I/I investigations are consummated and the flows to be handled
are known„
Two additional alternative procedures may be utilized to comply with
the intent of the law relating to the evaluation and rehabilitation of
tributary sewer systems on a proven cost-effective basis, but they are
not now universally accepted under USEPA procedures„ These possible
alternative procedures are outlined below:
A0 Sewer System Evaluation and Rehabilitation on the Basis of
Extending Facility Life
10 Prepare facility plan, including I/I analysis„
2. Design and build the treatment plant to handle current
and future average daily flows, with hydraulic capacity
for maximum flow loadings.
3« Concurrent with plant design and construction, conduct an
evaluation survey of the tributary sewer system.
4„ Rehabilitate the sewer system, on a mandatory planned
basis, to cost-effectively control I/I for the purpose
of meeting NPDES permit requirements and for extending
the useful life of the plant.
B. Sewer System Evaluation and Rehabilitation on the Basis of
Matching Actual Flows and Predicted Flows
1. Prepare facility plan, including I/I analysis.
2. Design and build treatment plant to.handle the estimated
flow in the sewer system based on the amount of rehabili-
tation required to meet cost-effective criteria.
3. Conduct, concurrently with plant design and construction,
a sewer system evaluation survey.
4e Rehabilitate the sewer system, on a mandatory planned
basis, to cost-effectively remove I/I, matching actual
flows to plant design capacity.
Feasibility of Rehabilitation Coincident with Evaluation Surveys
Strict interpretation of USEPA guidelines, in conformity with rules
and regulations covering I/I investigations, require the sequential
performance of the three Phases of such a program--Analysis; Evaluation;
Rehabilitation--without any transpositions or consolidation of these
procedures. Some consulting engineering firms and municipal engineering
personnel have proposed that rehabilitation procedures, particularly
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internal chemical grouting, should be allowed coincident with evaluation
of locations of infiltration. They rationalize that when joi^f focects or
other physical failures are found and recorded by internal inspection or
other photographic means it would be desirable to proceed immediately with
the sealing of such infiltration sources. This would make it unnecessary
to reclean sewer sections and to repeat internal inspection tasks, thus
expediting the rehabilitative program and saving time and money. This
school of thought holds that such rehabilitative costs could be reimbursed
when rehabilitation work is authorized and that close control over the
sealing program during the evaluation phase could be maintained to prevent
excessive sealing before the cost-effectiveness of rehabilitation work
has been established.
Other sewer system authorities believe that rehabilitation should
not be permitted until the evaluation procedures have been completed
and cost-effective analyses have demonstrated that sealing will be the
most desirable and economical means of handling I/I volumes „ Advocates
of this sequential procedure believe that over-sealing will be avoided
by this procedurea Depending upon the extent of structural damage and
number of leaks found, replacement of the line or lining might be cost-
effective and grouting unwarranted.
This Manual takes the position that there are convincing reasons for
withholding corrective sealing until adequate cost-evaluation decisions
can be made. In the future, if sewer investigative experience justifies
it, some type of compromise might be feasible, with certain sealing
operations permitted during the finding phase, under fund expenditure
control that would limit corrective actions to a specified percentage
of the total cost of the I/I investigation and rehabilitation program„
This compromise might permit immediate sealing of major i .filtration
sources having stipulated flow rates, where groundwater intrusion is
noted in the inspection program, or where obvious physical defects are
found during periods when groundwater levels do not subject the sewer
sections to infiltration conditions„
Explanatory Comments
This section has covered the procedural steps required in the
performance of Phase I and Phase II Analysis and Evaluation of sewer
system I/I conditions. It covers Phase III Rehabilitation—by
reference only.
Information concerning rehabilitation is provided in Section II on
Technical Procedures for Rehabilitation and Repair, as well as certain
matters covered in Section III on Technical Design Standards for New
Construction. Therefore, all sections of the Manual of Practice must
be interrelated and must be considered as complementing each other.
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SECTION II
GUIDE TO CLEANING, INSPECTION, TESTING
AND REHABILITATION OF SEWERS
Elimination or minimization of infiltration and inflow into public
sewer systems cannot be accomplished by halfway measures. The effort
involved in the preparation of sewer systems for necessary repair,
replacement and/or rehabilitation will be reflected in the soundness
of decisions as to which sewer sections will require such corrective
actions, how much work must be undertaken, and the means by which control
of excessive I/I should be carried put.
Present day sewer cleaning, inspection, testing and rehabilitation
techniques have taken the guesswork out of decisions which in the past,
had to be made "in the blind." By means of new equipment and technologies
for sewer cleaning, sophisticated electronic and photographic devices for
sewer inspection and recording purposes; advanced methods and mechanisms
for sewer testing and surveillance; and innovations in sewer pipe and
joints, pipe lining conduits and chemical grouting materials and mechanisms,
the whole art of sewer system construction, replacement, repair and rehabi-
litation has been changed in the past half decade.
These improvements have been applied to the I/I control problem in
the years since the APWA Research Foundation prepared its Manual of
Practice on the prevention and correction of excessive wastewater intrusion
into sewer systems in 1970. It is necessary to provide new "how to"
information on sewer line cleaning, sewer line inspection, sewer line test-
ing and sewer system rehabilitation, as part of the reevaluation of I/I
problems. Cost data for these procedures and technologies, upon which to
base cost-effectiveness decisions, are needed.
The following guidelines on these phases of I/I control were prepared
by a subcommittee of.the TAG which was designated to develop an overall
guide covering new methods, mechanisms and materials now available for
this purpose.
Generally, this section will focus on sanitary sewer collection systems
consisting of 6 in. (15 cm) through 3 ft (91 cm) diameter conduits, manholes,
lift stations and other related structures. Deviations from this general
scope are identified.
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SEWER LINE CLEANING
Cleaning Objectives:
o Remove blockages in emergency situations
o Restore full capacities and self scouring velocities (reduction
of septic conditions and hydrogen sulfide generation can increase
sewer system life)
o Locate breaks, offset joints, restrictions, and poor building
sewer connections
o Expedite manual inspection, lamping, and flow measurement
o Prepare sewers for effective photographic or TV inspection
o Prepare sewers for internal grouting, using sealing packers, or
for other rehabilitation procedures.
Adequate Cleaning Defined: Cleaning in preparation for photographic or TV
inspection must be performed more thoroughly than for routine maintenance.
Pipe walls must be clean enough for the camera to discern structural defects,
misalignment and points of infiltration. In this phase, small amounts of
debris left on the sewer invert, such as sand, stone or sewage solids, may
not interfere with effective inspection except in 8 in. (20 cm) pipe where
camera clearance is minimal. Root curtains and grease which" would foul
the camera lens must be removed.
Cleaning in preparation for internal pipe grouting, using a sealing
packer, or for other rehabilitative procedures, must be much more thorough
than for general sewer maintenance. All sand, rocks, gravel, bricks,
grease, mud, sludge and other debris must be removed from the sewer invert
to permit operation of a TV camera and sealing packers. It is usually
desirable to perform the cleaning immediately prior to internal grouting
operations to preclude the buildup of materials from I/I sources and the
shoaling of wastewater debris. A full diameter tool or cleaning device
is often required to assure adequate cleanliness and clearance for internal
inspection and rehabilitation procedures.
Materials to be Removed; The bulk of sewer cleaning is involved with the
removal of sludge, mud, sand, gravel, rocks, bricks, grease and roots from
pipes, manholes, and wet wells. Other coarse material may be found in
combined sewer lines. Removal of bricks, pieces of tile and clean sand
indicates structural problems such as broken or collapsed pipe.
Cleaning Equipment and Methods:
cleaning are intended to:
The primary tasks to be performed in sewer
1. Dislodge materials
2. Move materials to a point of access
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3. Remove materials from the sewer system.
Most cleaning techniques also require access for manpower or equipment
at the downstream manhole where materials are to be removed. Some cleaning
techniques require equipment access to both ends of a manhole section or
sections. This requirement may be a source of difficulty.
Disposal of the material removed is an additional important considera-
tion. In urban areas long distances to points of disposal may be required.
There are five basic types of sewer cleaning equipment:
1. Rodding machines and accessory tools
2. Bucket machines
3. High velocity water machines
4. Hydraulically propelled devices
5. Debris removal devices.
Equipment is available from manufacturers and suppliers for each
classification, with characteristics ranging from light to heavy-duty
application. Each class of cleaning equipment can utilize special attach-
ments, tools, and methods to expand its capabilities so as to overlap with
the primary applications of other types of cleaning devices. Cleaning
equipment will be evaluated in this Manual, with emphasis on the primary
application which results in more effective utilization of each technique.
The evaluation should not be considered as excluding the application of any
technique to other tasks involved in the great variety of sewer cleaning
situations.
1. RODDING MACHINES AND ACCESSORY TOOLS
Material to be Removed:
o Most effective application is for dislodging roots and
blockages
o Applicable for dislodging and transporting-sludge, mud and
grease, using proper tools and adequate flushing water.
Pipe Size Range:
o Generally 6 in. (15 cm) to 15 in. (38 cm), due to the
tendency of rods to bend and the limited pulling power in
' larger diameter pipes.
Technique Advantages:
o Fast response to emergency stoppages
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o Can generally reach 1,000 ft (305 m) of line
o Requires no threading; is often used for threading sewer
lines, preparatory to insertion of other cleaning or inspec-
tion equipment.
Technique Limitations;
o Direct access to downstream manhole is required
o Large quantity of water is required for "brush and flush"
cleaning
o
o
Generally ineffective for transportation of heavy solids
Technique does not remove materials from sewer.
2. BUCKET MACHINES
Materials to be Removed:
o Most effective application is for dislodging, transportation
and removal of sand, gravel, rocks, bricks, and roots
o Applicable for dislodging and transporting mud and grease.
Pipe Size Range;
o Generally, 18 in. (46 cm) to 36 in. (91 cm) lines provide
best use of the available power, although sizes 8 in. (20 cm)
to 15 in. (38 cm) can be cleaned.
Technique Advantages;
o Provides the "iron and power" for removal of large amounts
of heavy solids and roots
o Effective in large diameter pipes
o Can remove materials from sewer system
o Availability of a wide variety of accessory tools.
Technique Limitations:
o Complete access to both manholes is required
o Threading the sewer line is necessary
o Time consumed is longer than for other methods for light
cleaning
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o Uses heavy tools and has the power to damage pipe
o Structurally damaged pipe, offset joints, intruding service
connections, and curved pipe can preclude the use of bucket
tools.
3. HIGH VELOCITY WATER MACHINES
Materials to be Removed;
o Most effective application is for dislodging and transporta-
tion of sludge, mud, sand, and gravel
o Applicable for dislodging and transporting rocks and grease
in pipes up to 12 in. (30 cm) diameter
o Capable of dislodging roots by using special tools in pipes
up to 12 in. (30 cm) diameter
o Effective for cleaning manhole walls and benches.
Pipe Size Range:
o Most effective in sizes 6 in. (15 cm) to 15 in. (38 cm)
o
Effectiveness in larger pipes is reduced except for cleaning
materials from the invert.
Technique Advantages:
o
Access of equipment to only the downstream manhole is
required
o Not necessary to thread sewer lines; the equipment can be
used for threading
o Setup is fast
o Fast method for light cleaning of debris is provided
o Ease of operation is assured
o Few operator safety hazards involved
o Low pipe damage potential is involved, except in badly
deteriorated pipe
o Effective for final flushing prior to rehabilitation work.
Technique Limitations:
o Water must be available reasonably near job
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o Least effective on large and heavy debris
o Can cause cavitation on open or broken pipes backfilled with
sand
o Does not provide for removal of materials from sewer system.
4. HYDRAULICALLY PROPELLED DEVICES
Materials to be Removed:
i
o Most effective application is for dislodging and transporting
sludge, mud, and sand
o Fair applicability for dislodging and transporting gravel,
rocks, bricks, and grease.
Pipe Size Range:
o Generally 8 in. (20 cm) to 36 in. (91 cm)
o Best in intermediate sizes, with extreme caution required in
large pipes.
Technique Advantages;
o No equipment access limitations
o Minimum equipment requirements
o Ease of operation
o Minimum operator safety hazards.
Technique Limitations;
o Large quantity of water is required at site
o Significant basement flooding is a possibility; may be used
only where head in sewer will not exceed basement or drain
elevations
o Not applicable to blockages resulting in surcharge conditions
o Extreme caution required when using hydraulically propelled
devices in large pipes due to the large propulsive force and
the hazard of getting stuck in the line
o It does not provide fcr removal of materials from sewer
system.
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5. DEBRIS REMOVAL DEVICES
Although primarily used for catch-basin cleaning, these
machines are often used for removal of most materials from
manholes when other cleaning equipment is used to dislodge
and transport the materials, to the access point.
Trash Pumps:
o Trailers (sometimes containing pumps and settling baffles)
are frequently used to separate solid materials from clean-
ing water and to transport the debris to a dump site.
Cleaning Precautions
o Clean soil and pieces of broken tile observed in a manhole
trough are strong indications of broken, crushed, or
collapsed pi]5e in the upstream section. Exercise due
caution prior to any cleaning.
o Eroded or corroded, or otherwise structurally deteriorated
pipe may collapse during cleaning operations. Visible
inspection (lamping) must be used to ascertain the advis-
ability of cleaning. Sometimes photographic or television
inspection must be used prior to cleaning in such situations.
o Full gauge cleaning tools, including hydraulically propelled
devices, are subject to getting "hung up" on offset joints
intruding service connections, root masses, and other
obstructions., A tag cable and winch should be used whenever
possible to retrieve cleaning tools and devices.
o Pipe damage is possible any time powerful cleaning equipment
is used. Cleaning equipment and tools should'be matched to
both the job and pipe conditions to avoid damage.
o Basement flooding is possible any time hydraulically pro-
pelled devices are used. High velocity jet machines have
been known to remove and expel water from non-vented closet
traps.
Difficulty and Cost Factors Which Affect Cleaning Operations
o Access to manholes, terrain and traffic control limitations
o Condition of manholes - steps, cleanliness and structural
integrity
o Size of pipe
o Depth of deposition in pipe
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o Type of solid materials to be removed, arranged in order of
increasing difficulty - sludge, mud, sand, gravel, rocks,
grease, bricks, and roots. Roots are difficult to dislodge
and remove completely and may be a significant factor.
o Degree of root intrusion, due to difficulty in removal
o Depth of sewer
o Amount of flow, either advantageous or disadvantageous
o Structural integrity of pipe
o Offset joints, intruding service connections, curved pipe
o Availability of hydrant water
o Degree of cleanliness required
o Differences in productivity in cleaning successive sections
vs. random sections
o Requirements for transportation and disposal of solid
materials and distance to the disposal site.
SEWER LINE INSPECTION
Purposes of Inspection:
o Inspect new construction prior to acceptance
o Assure sound pipes prior to paving
Find problems in troubled areas
o
o
Pinpoint the cause, source and magnitude of infiltration
into sewer lines and appurtenant structures
o Locate improper or illegal connections and sources of inflow
and evaluate the need for their elimination
o Ascertain the advisability and applicability of various
methods of rehabilitation
o Estimate the amount of infiltration reduction obtainable
with various rehabilitative procedures.
Inspection Techniques; There are three basic classifications of sewer
inspection techniques. Each has some advantages and limitations when used
for various purposes under specific sewer conditions.
1. Television Inspection
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2. Photographic Inspection
3. Manual/Physical Inspection.
TELEVISION INSPECTION
Applications;
TV inspection provides continuous live inspection up to 1,000 ft
(305 m) away in pipe sizes 0.5 to 3 ft (15 to 91 cm). The technique
is well suited for determining joint conditions, root intrusion, and .
sources of I/I, and can be used for analyzing structural deficiencies,
line and grade, and quantity of infiltration. Inspection documentation
is normally made with videotape or black-and-white photographs of the
TV monitor. Combination TV and photo cameras can provide in-line
color photographs.
Technique Advantages:
Since TV inspection is "live," precarious conditions in the pipe
can be approached with due caution. Control of the inspection is
achieved by the ability to stop, back up, and position camera as
desired. Problems can be discussed, analyzed, and photographed and
footage noted during the course of the inspection. TV inspection
provides definition of I/I sources, estimation of flow rates, and the
only practical method to monitor flow from building sewers.
Technique Limitations:
i
o Provides black-and-white TV picture only, unless combined
with in-line photographic capability.
Exhibit 1 is a typical form for recording the results of a TV
survey.
PHOTOGRAPHIC INSPECTION
Applications:
o Provides in-line black-and-white or color photographs at
equidistant intervals
o Pipe sizes 8 in. (20 cm) to 36 in. (91 cm) can be inspected
o Allows analyses of structural deficiencies •
o Applicable'for determining joint conditions and root
intrusion.
Technique Advantages:
o Equipment cost and complexity are moderate
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EXHIBIT 1. TELEVISION INSPECTION REPORT
Date
Nearest Intersection
Location
Area
Paoe
Code No.
W. O. No.
Vehicle No.
No. of Personnel
Fuel Used Gal.
Sanitary
Storm
Flow Level S. F.
Diameter
Material
Section Length
Total Length
Temp.
Weather
Time A.M. P.M.
Recent Rain?
Within 48 Hrs.?
Area Elevation
Any M.H. Infiltration?
District No.
Foreman
Camera On Off
No. of Photos
Video Tape?
Reel No.
Location on Reel
Total Project Time Hrs.
Sealing Required?
Se
Ftq.
rvice Co
Quad.
nnecti
Ftq.
3ns
Quad.
Root Intrusion
Infiltration
M.H. Infiltration
Give Quadrant No.
Off -Set Joints
Broken Pipe
Loss of Grade or
Alignment
Conn, with Roots
Extended Conn.
Address of Each
Grease, Scrap,
Debris, or
Obstructions
State Type
Remarks, Over-All M.H. & Step Cond., Pipe Cond., Recommendations:.
Camera Direction
A re all M.H.s Accessible?
_A pprox. M.H. Depth to lnvert_
Report Prepared By.
Quadrants
| Street]
Pipe Layout
_J Street [_
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o Color photographs for analysis and documentation are provided
o Provides, with a combination of TV and photo cameras, in-line
color photographs which are best for discerning structural
deficiencies and joint conditions at some increase in equip-
ment complexity and camera size.
Technique Limitations;
o Effective in new construction inspection where unpredictable
conditions in the pipe are not as often found as in existing
pipe
o Hazardous to pull a camera into a sewer suspected of having
structural problems or obstructions
o Involves the inability to position camera for optimum view
of defects as problem locations are not known
o Very difficult to define I/I sources and impossible to quan-
tify them, since water movement cannot be observed and moni-
tored
o Roots, grease., paper and other debris can foul the camera
lens without operator's knowledge
o Inspection results are unknown until film is successfully
processed.
3. MANUAL/PHYSICAL INSPECTION
Lamping:
Hand-held mirrors using sunlight or a portable lamp provide
simple visual pipe inspection for short distances from manholes
depending on pipe size, flow, and conditions. Although the technique
has obvious distance limitations, a first hand observation of pipe
conditions near manholes is valuable because severe structural prob-
lems often exist due to manhole settling.
Crawling:
Although generally limited to new construction, storm sewers, or
lines not in service, crawling is the most direct method for detailed,
accurate inspection of an entire manhole section. The technique is
applicable to lines 30 in. (76 cm) and larger. Proper cautions should
be observed regarding ventilation, lighting, and protection from sharp
debris.
Estimated Visible Infiltration Rates
It is desirable to quantify I/I from various sources in order to assign
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potential extraneous flow reduction to the available and applicable rehabili-
tation techniques.
Infiltration rates into manually accessible locations (manholes, wet
wells) is simply estimated from experience or are captured and measured when
practical. A method of the estimation of flow rates is to spend some time
with a garden hose and a one-gallon container. Flow rates of 0.5, 1, 2,
4, and 8 gpm (1.0, 3.7, 7.6, 15.1, and 30.3 1/min) will take 120, 60, 30,
15, and 7.5 seconds, respectively, to fill the 1 gal (3.8 1) container.
Note particularly that 8 gpm (30.3 1/min) is about the maximum flow from a
garden hose. The visible estimation of flow rates is not an exact science.
An observer will do well to make estimates within a factor of two, especially
in the field where flow sources are considerably less defined than the flow
from a hose. Estimates within 50 percent represent a "handle" on infiltra-
tion point quantification which can be used to establish the desirability
of rehabilitation.
Estimating infiltration rates of sources withiii a manhole section from
TV inspection involves other considerations. Since the size of the TV screen
is fixed, a given size leak will appear much more dramatic in a small pipe
than a large pipe. In addition, sewer pipe leaks often have several points
of entry and can be up, down and sideways at the same time. Leaks can appear
as streams, drippers, runners, trickles and boils from the bottom. A hand-
book containing in-line pictures of known size leaks, in several modes,
taken in each size of pipe, should be developed as a training tool for infil-
tration rate estimators.
The important thing to remember is that a fairly good quantification
of the total extraneous flow from a manhole section exists prior to in-line
inspection (i.e., night flow measurements). The real purpose of the inspec-.
tion is to establish approximately how much of the known extraneous flow is
coming from in-line sources such as:
o
o
Structurally damaged pipe - may require excavation/replacement
Running building sewers - may be due to leaking joints, broken
pipe, foundation drains, or sump pumps
o Leaking pipe joints - may suggest chemical grouting with a sealing
packer
o Leaks adjacent to manhole - may be sealed without full section
set up expense
o Leaks around improperly made service connections - may not suggest
any feasible remedial procedure.
Not all of the extraneous flow from a manhole section will be observed
during internal inspection, nor will individual source estimates have a high
degree of accuracy. Yet, visible I/I sources can be classified and quanti-
fied to the extent necessary to determine the applicability and practicality
of various rehabilitation alternatives.
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Footage Measurements
Photographic and TV inspection records must log each defect or item of
interest with respect to its distance from an established point. Distance
is recorded in feet from the center of the starting manhole to the plane of
focus of the camera. With TV inspection the following procedure is used:
1. The TV camera is focused for the clearest view of the pipe
wall in the size pipe being inspected.
2. The TV camera is pulled into the line and stopped when the
first pipe joint is in clear view.
3. The down-hole gear is set and the top-hole roller put in
place; slack is taken out of the tag cable, and the footage
meter is set at the measured or closely estimated distance
from the center of the manhole to the first pipe joint.
Since footage is always measured from the center of the manhole from
which the camera is pulled, it is important that the manhole .be identified
beyond any doubt.
Information to be Recorded
The inspection report should contain explicit information to identify
positively the manhole section and starting manhole from which footage
measurements are made. The report (log) should contain (but not be limited
to) the following information:
Client or Owner's Name
Inspector's Name
Crew Chief's Name
Date
Time
From MH No.
To ME No.
located at
located at
Direction of Measurement
Direction of Flow
Direction of North
Type of Pipe
Type of Joint
Cleanliness
Manhole Conditions
Section Length
Pipe Size
Each item of interest, structural defect, I/I source, building sewer,
etc., should be logged as to location (footage and clock reference) and
described as to severity or magnitude.
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Terminology
Efforts to attain better levels of I/I control must be based on a uni-
form understanding of the "language" of the field. The following clarifica-
tion of the meaning of pertinent terms used in cleaning, inspection, testing
and rehabilitation of sewer systems is provided:
Areaway—A paved surface, serving as an entry area to a basement or subsur-
face portion of a building, which is provided with some form of drainage
device that may be connected to a sewer line.
Building Sewer—The conduit which connects building wastewater sources to
the public or street sewer, including lines serving homes, public buildings,
commercial establishments and industry structures. In this manual the
building sewer is referred to in two sections: (1) the section between the
building line and the property line, frequently specified and supervised by
plumbing or housing officials; and (2) the section between the property line
and the street sewer including the connection thereto, frequently specified
and supervised by sewer, public works, or engineering officials. (Referred
to also as house sewer, and building connection).
Bypass—A pipe line which diverts wastewater flows away from or around
pumping or treatment facilities - or bypasses such facilities in order to
limit the flows delivered to such facilities and to prevent surcharging or
adversely affecting their operation or performance.
Cellar Drain—A pipe or series of pipes which collect wastewaters which
leak, seep, or flow into subgrade parts of structures and discharges them
into a building sewer, or by other means dispose of such wastewaters into
sanitary, combined or storm sewers. (Also referred to as basement drain).
Clean Waters— Wastewaters from commercial or industrial operations such as
cooling or process water which are uncontaminated, do not need, and
could not benefit from wastewater treatment processes and which for sanitary
purposes do not require disposal into public sewers, particularly separate
sanitary sewers.
Collector Sewer—A sewer located in the public way which collects the waste-
waters discharged through building sewers and conducts such flows into larger
interceptor sewers and pumping and treatment works. (Also referred to as
street sewer).
Compression Gasket—A device which can be made of several materials in a
variety of cross sections, which serves to secure a tight seal between two
pipe sections (i.e., "0"-ring).
Exfiltration—The leakage or discharge of flows being carried by sewers out
into the ground through leaks in pipes, joints, manholes, or other sewer
system structures; the reverse of "infiltration."
Foundation Drain—A pipe or series of pipes which collects groundwater from
the foundation or footing of structures and discharges these waters into
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sanitary, combined, or storm sewers, or to other points of disposal, for the
purposes of draining unwanted waters away from such structures.
Interceptor Sewer—A sewer which receives the flow from collector sewers
and conveys the wastewaters to treatment facilities.
Joints—The means of connecting sectional lengths of'sewer pipe into a con-
tinuous sewer line, using various types of jointing materials with various
types of pipe formations that make possible the jointing of the sections of
pipe into a continuous collecting sewer line. The number of joints depends
on the lengths of the pipe sections used in the specific sewer construction
work.
Overflow—A pipe line or conduit device, together with an outlet pipe, which
provides for the discharge of portions of combined sewer flows into receiving
waters or other points of disposal, after a regulator devicethas allowed the
portion of the flow which can be handled by the interceptor sewer lines and
pumping and treatment facilities to be carried by and to such water pollu-
tion control structures.
Regulator—A device or apparatus for controlling the quantity of admixtures
of sewage and storm water admitted from a combined sewer collector line into
an interceptor sewer, or pumping or treatment facilities, thereby determining
the amount and quality of the flows discharged through an overflow device to
receiving waters or other points of disposal.
Roof Leader—A drain or pipe that conducts stormwater from the roof of a
structure, downward and then into a sewer for removal from the property,
or onto or into the ground for runoff or seepage disposal.
Terms Frequently Used in Inspection R.eports
Manhole Components:
Manhole Cover—(self explanatory).
Manhole Ring (frame)—Usually an iron casting used to top off the
manhole and to act as the base for the cover.
Corbel Work—The portion of a manhole (often brick) which supports the
ring and makes the transition to the vertical manhole walls.
Walls— The vertical (usually cylindrical) portion of the manhole.
Internal Drop—Incoming sewage free-falls in the manhole to the trough.
External Drop—Incoming sewage drops to the trough in a vertical pipe
outside the manhole wall.
Aprons (bench)—Standing room at the bottom of the manhole, containing
the trough.
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Trough—The channel at the bottom of the manhole through which sewage
flows.
Invert—The exact bottom of the pipe or trough.
Invert Elevation—The height above sea level of the sewer invert.
Depth of Invert—The distance from the top of the manhole ring (street
surface) to the sewer invert.
Base—The structural foundation of the manhole.
Type of Pipe and Abbreviations
Acrylonitrile-butadiene-styrene
Asbestos-Cement
Brick Pipe
Cast Iron Pipe
Concrete Pipe
Corrugated Metal Pipe
Polyethylene
Polypropolene
Polyvinylchloride
Reinforced Concrete
Reinforced Plastic Mortar
Steel Pipe
Vitrified Clay
Types of Sewer Joints
(ABS)
(AC)
(BP)
(CIP)
(CP)
.(CMP)
(PE)
(PP)
(PVC)
(RC)
(RPM)
(SP)
(VC)
Asphaltic/Bituiainous
Cement Mortar
Compression Gasket (0-ring, molded elastomeric seal, etc.)
Solvent Weld
Thermal Weld
Type of Debris
Sludge - organic materials
Silt - light soil
Mud - clay soil
Sand - sand, soil and grit
Gravel - smaller than 0.5 in. (1.3 Cm)
Rocks - larger than 0.5 in. (1.3 cm)
Bricks
Grease
Roots
Root Curtains - growth mats that fill most of area above water level
Root Blockages - growth which fills the pipe and causes stoppage of
flow
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Type of Service Connections (Locate by clock reference)
Wye - manufactured pipe, fitting, enters main pipe at an angle other
than 90°
Tee - manufactured pipe fitting, enters main pipe at 90° angle
Saddle Tap - a device used for a cut-in connection
Intruding Service Connection - a building sewer pipe inserted into
the collector sewer (street sewer); often through a hole broken
in the side of the collector sewer which protrudes into the
sewer .
Descriptive Terms of Pipe Defects
and footage)
(Locate defects by clock reference
Cracked Pipe— *-crack lines visible, pieces still in place
Open Crack — crack opening visible, pieces still in place
Broken Pipe — pieces displaced, some pieces could be missing
Crushed Pipe — extensively broken and out-of -round pipe
Collapsed Pipe — all structural integrity lost, pipe flattened out
Circumferential Defect — a circular peripheral defect
Longitudinal Defect- — parallel to the pipe axis
Erosion — pipe worn away by the flow, generally near invert or at the
flow line
Corrosion — pipe deteriorated by acid or other chemical attack, generally
at crown
Offset Joint — the spigot of one section is not concentric with the
bell of the adjacent section
Separated Joint — longitudinal displacement of adjacent pipe sections
Dip — a divergence in elevation
Misalignment — a divergence in line (left or right) of pipe sections
Excessive Deflection — a flattening of a flexible pipe
Describing Infiltration
and footage)
(Locate infiltration points by clock reference
In describing the extent of infiltration, use of descriptive words
such as "seeper," "slow dripper," "dripper," "fast dripper," "runner,"
"fast runner," and "gusher" are nebulous and indefinite. Except for
seeping and dripping infiltration points having unmeasurable flow rates,
inf iltra'tion rates should be estimated as previously mentioned.
Difficulty and Cost Factors Which Affect Inspection Operations
o Location of manholes often unknown (paved over, etc.)
o Access to manholes 'for equipment and winches including terrain
and traffic conduit
o Manhole conditions - size, steps, cleanliness, state of repair
o Availability of water for threading line
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o Size of pipe - 6 in. (15 cm) to 10 in. (25 cm) is tight, and may
involve equipment clearance problems; 12 in. (30 cm) to 21 in.
(53 cm) is best for inspection; 24 in. (61 cm) to 36 in. (91 cm)
may require special illumination and skids
o Depth of flow, flow rate and flooding conditions
o Plugging requirements vs. ability to plug or necessity to bypass
o Presence of explosive gas or combustible liquid
o Cleanliness of pipe
o Presence of root curtains, grease, soap curd and other debris
could foul camera lens
o Offset joints, intruding joint materials, intruding service connec-
tions, crushed pipe and other obstructions which could prevent the
passage of the camera - these conditions can be overcome sometimes
by a reverse setup on a manhole section, at additional cost
o Unit cost of inspections is sensitive to mobilization of facilities
and number of setups required; it is possible to televise 1,000 ft
(305 m) in one direction from a single location when inspecting;
successive sections; random inspection of 300 ft (90 m) manhole
sections, however, is more costly
o Requirements for documentation by means of monitor photos, video-
tape, in-line photos, become an added cost factor
o Weather conditions such as temperature, rain or snow can affect
productivity rates; snow cover can hide manholes.
SEWER LINE TESTING
Purpose of Testing;
For new construction, to verify sewer to be structurally sound
within tightness specification requirements prior to acceptance, "
and to locate specific points requiring repair
For existing sewers, to locate points of inflow, overflow, or
cross connection in a sanitary sewer by means of smoke and dye
tests
For existing sewers, to quantify infiltration from a manhole
section or sections by early morning flow measurements
For existing sewers or new construction, to test individual pipe
joints prior to and/or after joint sealing operations.
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Detailed descriptions of infiltration, exfiltration and air pressure
testing are given in Section III with regards to acceptance testing.
Testing Techniques for Lines in Service
1. Flow Measurement;
o When a sewer is below the water table, flow measurements can be
made on a section or sections in early morning hours. By reducing
flow measurements by the estimated nighttime sewage flow the I/I
extraneous flow rate can be estimated.
o Since extraneous flow is likely to be from numerous sources,
including all building sewers, and as some of the flow may be
inflow from foundation drains and sump pumps, approximated extra-
neous flows should generally exceed 5 gal/min (18.9 1/min) per
manhole section to justify further investigation. It is a fast,
direct method to quantify I/I in a single manhole section or an
entire subsystem.
o Flow depth recorders at key manholes can provide round-the-clock
flow rate information and record responses of sewer system to
rainfall.
o Flow measurements are usually made by plugging and weiring indivi-
dual sectidns, weiring at key manholes, or taking velocity and
depth measurements at key manholes.
Comment: Moderate equipment requirements, is the fastest method to
provide an estimate of extraneous flow rates. Involves a safety
hazard from toxic or asphyxiating gas in manholes.
2. Smoke Testing;
o Test is performed by blowing low pressure, non-toxic, non-staining
smoke into a plugged off sewer manhole section.
o Effective for detecting sources of inflow—area drains, roof
leaders, abandoned building sewers, faulty connections, illegal
connections and other sources. Sometimes detects structural
damage, overflows and storm sewer cross connections.
o Involves minimal equipment requirements, documents system defects
usually by photographs of smoke leaks, represents no safety hazards.
However, considerable public relations efforts and notification of
fire department is usually required.
Smoke testing should be conducted by experienced personnel who know the
effects of groundwater table, frozen ground, wind, rain, trapped service
connections, and snow cover on test findings.
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2. Dye Testing:
o Dyed water flooding of a storm sewer section is usually performed
to detect cross connections with the sanitary sewer, both man made
and accidental.
o Dyed water surface flooding is used to detect inflow sources, such
as area or footing drains and to simulate infiltration through
porous dry soils.
o Method involves minimal equipment requirements and availability of
hydrant water; documents defects usually by logging appearance of
dye in sanitary sewer manhole; represents some safety hazard in
retention and removal of storm sewer plugs.
4. Chemical/Biological Testing;
o Chemical and biological sampling and testing performed at key
locations throughout a sewer system can indicate relationships
between sanitary flows and I/I intrusions.
o In coastal areas, saline water intrusion into the grouridwater
may be detected in sewer samples where infiltration may be high.
o The use of fluoridation in a city water supply may produce the
presence of this chemical in clean water discharges into a sewer
system.
Difficulty and Cost Factors Which Affect Testing Operations
o Applicability of factors depends on type of testing being
considered.
o Locations of manholes are often unknown.
o Access to manholes involves excavation if they are paved
over.
o Condition of manholes involves cleanliness, presence of manhole
steps and physical integrity of walls, floor and troughs.
o Pipe size and depth.
o Cleanliness of pipe during flow measurements is essential.
o Amount of flow.
o Weather conditions.
o Availability of adequate amounts of hydrant water.
o Presence of hazardous gas in manholes.
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o Successive sewer sections vs. random testing of separated sections
can affect unit costs.
SEWER SYSTEM REHABILITATION
Purposes of Rehabilitation;
o Preservation of pipe lines and appurtenant structures in order to
assure their useful life and ability to withstand the effects of
age, erosion, corrosion, settling and loading.
o Correction of existing structural deficiencies and incipient struc-
tural failure from all causes.
o Reduction or elimination of exfiltration and infiltration and, in
some instances, inflow.
Deficiencies Considered for Rehabilitation:
The following collection system deficiencies are usually considered when
rehabilitation decisions are made. Causes of deficiencies can range from
inadequate design or construction to old age:
o Broken or crushed pipe
o Deteriorated pipe
o Deteriorated or cracked pipe or mortar joints in brick sewers and
manholes
o Manhole walls, bases and troughs
o Cracked pipe
o Leaking pipe joints in street sewers
o Leaking building sewers
o Leaking manhole external drops
o Leaking or deteriorated wet wells and lift stations, regulator
structures and tide gate chambers
o Defective regulators and tide gates
o Improperly supported pipe
o Deteriorated or leaking manhole walls, bases or troughs
41
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Rehabilitation Techniques
A large number of rehabilitation techniques are available to cope with
the myriad of sewer system deficiencies, conditions and restraints. When
evaluating the various methods of rehabilitation, it is important to discern
the proper applications, advantages, and limitations of each technique.
Technique selection should be made from applicable procedures on cost-benefit
considerations or important local conditions.
Available techniques are:
o Excavation and Replacement
o Chemical Grouting
- Acrylamide Gel
- Urethane Foam
- Cement
o Exfiltration Sealing
o Pipe Lining
- Polyethylene
- Glass Reinforced Polyester Mortar
- Cement Mortar and Epoxy Mortar
- Gunite
- Concrete Shells
- Metal
o Brick Mortar Replacement
- Hand Troweled
- Mechanical Extrusion
The most frequently used techniques will be evaluated in detail.
Excavation and Replacement
Excavation and replacement of existing pipe and appurtenant structures
may involve pavement removal, disruption of traffic, public inconvenience,
dewatering, well pointing, shoring, interference with existing utilities/
structures, bypassing of sewage flows, and repaving. The total cost of
replacement must be considered when comparing it with other rehabilitative
techniques. For building service lines where infiltration is confirmed, the
cost of investigation to allow alternate means of rehabilitation must also
be considered.
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Applications
o For broken, crushed and collapsed pipe
o For badly deteriorated pipe, manholes, cracked pipe, and building
sewers where other rehabilitative techniques would not give the
quality or permanence of replacement'
o For realignment of line or grade
For increase in size and carrying capacity of sewer
o
o
For building service lines where connection to line was improperly
made or where transfer from storm sewers to service line is con-
firmed.
Criteria for Proper Application
o Used when structural integrity is lost, precluding other rehabilita-
tive procedures.
o Used when the cause of damage (corrosion, movement, loading) is
identified so as to prevent reoccurrence using standard construc-
tion practices.
Technique Advantages
o Replacement is long lasting if construction and materials are
matched to conditions.
o Replacement gives the highest strength rehabilitation.
o Replacement presents the opportunity to increase conduit size while
correcting deficiencies.
GROUTING
Pipe grouting refers to the placement of a material (grout) on, in, or
outside of sewer pipe joints for the purpose of preventing exfiltration of
sewage or infiltration of water, soil and roots through defective joints.
One objective of pipe grouting is to-stop groundwater and soil infil-
tration in order to prevent road surface cave-ins and eventual collapse of
the pipe itself through loss of bedding material. Since 1963, pipe grouting
has become increasingly important as a means of reducing sewage treatment
plant load due to groundwater infiltration into sanitary sewers.
Manually accessible storm and sanitary sewers were first grouted by the
hand application of quick setting hydraulic cement to joints and lift-holes.
This technique is still used where applicable, but usually in preparation
43
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for the injection of chemical grout to provide a more efficacious seal.
Hydraulic cement is difficult to apply to actively infiltrating leaks, and
sometimes must be done during the dry season.
External pipe grouting with cement, bituminous materials, sodium sili-
cate/calcium chloride, acrylamide gel, and other grouts was started about
1957. The technique involves jetting an injection pipe from ground level
to the vicinity of the leak and pumping grout into the area. The procedure
is somewhat "hit-and-miss" and quantities of grout are likely to enter the
pipe through the leaks.
Internal pipe grouting with mechanical packers using cement paste grout
was attempted in the late '50's. A thick paste consisting of cement and
additives to achieve a very low slump was placed between compressing squeegees
and pulled through the line. It was necessary to plug or bypass the section
under repair. Sealing results were uncontrollable. Sanitary sewers have
service connections, off-set joints, and frequent structural problems which
generally preclude application and practicality of this procedure.
Sealing sewer pipe leaks by the exfiltration of slurries containing
sodium silicate was attempted in the early '60's. Exfiltration sealing of
leaking sewers involves plugging-off or bypassing the section under treatment.
It is necessary to surcharge the section with slurry to at least 4 ft (1.2 m)
above groundwater level to achieve 2 psig (0.07 kgf/cm2) exfiltration dif-
ferential. Plugging, bypassing, and surcharging often involve severe imprac-
ticalities and the danger of flooding service connections. Although good
results have been reported under limited conditions, only partial or temporary
benefits have resulted from most exfiltration sealing applications.
Internal sealing of pipe joints with pneumatic packers using acrylamide
gel grout was introduced commercially about 1960. By the mid T60's, transis-
torized electronics made possible the production of small, rugged, water-
proof, high resolution, self contained closed circuit .television (CCTV)
cameras. Inspection and joint-by-joint sealing in sanitary sewer pipes as
small as 6 in. (15 cm) diameter became feasible with the camera/packer
combination. Process control is inherent as infiltrating joints can be
located and visibly inspected after sealing. The system enjoys certain
practicalities: packers are made smaller than the sewer pipe in order that
they can negotiate off-set joints and some intruding service connections.
Also, the packers are in the form of a hollow cylinder which permits normal
sewage flow during sealing operations without.plugging or bypassing in most
cases.
*
A flexible seal is made outside of the pipe when using the AM-9 type
chemical sealant. Pipe grouting with acrylamide gel has been the.most
widely used grouting process since the early '60's and will be discussed in
detail.
* Registered Trademark of American Cyanimid Company.
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Internal sealing of pipe joints with pneumatic packers using urethane
foam grout was introduced commercially about 1972. The mechanism of sealing
is to place a foamed gasket in the joint area. Mechanical locking of the
expanded foam in the joint and a limited degree of adhesion provides reten-
tion. Pipe grouting with urethane foam will also be discussed in detail.
Limitations to Grout Sealing
o Improperly supported pipe may continue to move after joints are
sealed.
o Grouting is not a structural repair. Broken, crushed, and badly
cracked pipe are candidates for excavation/replacement, and inter-
nal pipe grouting with a sealing packer should not be attempted.
o Sealing packers can be used only where the inflatable sleeves
straddle the leak point and make continuous contact with sound
pipe on each side.,
' Exhibit 2 is an example of a form which can be used to record the re-
sults of a grouting program.
Acrylamide Gel
Acrylamide Gel is a mixture of two organic monomers: Acrylamide and
N,N - Methylenebisacryland.de. When a dilute aqueous solution (usually
10 percent of batch weight) is properly catalyzed, gelation occurs by a
polymerization-crosslinking reaction, forming a gel. B-Dimethylaminopropio-
nitrile (Catalyst DMAPN) is a somewhat caustic liquid used as an activator
for the reaction (usually 0.5 percent to 1.5 percent of batch weight).
Ammonium persulfate (AP) is a strong oxidizing salt, used as the initiator
that triggers the reaction. The induction period (gel time) begins with
its addition. The ammonium persulfate is added as an,aqueous solution
(usually 0.5 to 3 percent of batch weight).
Gel time can be controlled from 5 to 500 seconds by the weight percent
of DMAPN and/or ammonium persulfate used. A gel time of approximately 20
seconds is commonly used in sewer grouting. Longer gel times are generally
used in structural waterproofing, with lower flow rates and deeper penetra-
tion.
A 10 percent solution of Acrylamide gel has a specific gravity of 1.04
and a viscosity of 1.2 centipoise (water = 1.0 centipoise). The grout can
penetrate small leaks and cracks through which ground water is flowing.
Since the grout is about 87 percent water at the outset, it is not
adversely affected by the presence of water other than by dilution. When ,
injected into sand or sandy soil, the grout tends to displace rather than
to mix with the ambient water. When injected into coral sand, gravel, or
rock, dilution can render the grout ineffective, especially in the presence
45
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EXHIBIT 2. TELEVISION SEALING REPORT
Date
Nearest Intersection
Location
Area
Paoe
Code No.
W. O. No.
Vehicle No.
No. of Personnel
Fuel Used Gal.
Sanitary
Storm
Flow Level S. F.
Diameter
Material
Section Lenqth
Total Lenqth
Temp.
Weather
Time A.M. P.M.
Recent Rain?
Within 48 Hrs.?
Area Elevation
Any M.H. Infiltration?
District No.
Foreman
Camera On Off
No. of Photos
Video Tape?
Reel No.
Location on Reel
Total Project Time Hrs.
Date of TV Inspection
Footage of Joints or Repairs Made
If Other Than Joint Renovation
Ftq.
Gal.
Ftq.
Gal.
Ftq.
Gal.
Injection Time Standard Minutes Seconds
Cure Time Standard Minutes Seconds
Gel Time Minutes Seconds
Injection Pressure psi
Packer Inflation Pressure psi
Was Root Inhibitor Grout used?
f
Was Excess Gel Removed After Repair?
.
Operation?
Total Chemical Injected ,
Comments
Chemicals
And Mix Information
(As appropriate for type
of grout used.)
Protective Clothing and
Gear must be used when
mixing or during any
exposure to Chemicals.
Don't just think Safety!!
Keep an Eye on it !!!
Camera Direction
Report Prepared By
Are all M.H.'s Accessible?
Approx. M.H. Depth to Invert
Quadrants
I Street I
Pipe Layout
| Street |
46
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of moving groundwater. The use of a higher grout concentration and thicken-
ing additives can overcome these problems.
Some areas have clay soil with such low permeability as to be
considered ungroutable,from a soil stabilization viewpoint. When acrylamide
gel is used to seal sewer pipe joints, soil makeup in the trench surrounding
the pipe (backfill) rather than local soil permeability controls the grout-
ing process. Appurtenant structures such as manholes, however, are likely
to be backfilled with local soil. Experience and a knowledge of local
conditions are more valuable than hard and fast rules for the application
of acrylamide grout.
Acrylamide gel grout has an application history dating from 1960.
Internal grouting of structurally sound pipe joints is the most widely
used application. Pipe joint sealing is accomplished with packers using
the following method, basically described as follows:
Placement;
1. A hollow metal cylinder having inflatable rubber sleeves on each
side of a center band is positioned on a pipe j oint as shown in Figure 3.
Source: American Cyanimid Co.
Figure 3. Internal grouting with hollow metal cylinder
flanked by inflatable rubber sleeves placed
over pipe joint.
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2. Air pressure is introduced underneath the rubber sleeves causing
them to expand and seal against the internal pipe wall on each side of the
joint to be sealed.
3. Chemical grout is pumped into the void created between the two
inflated sleeves.
4. The chemical grout and the initiator mix together in the void
and are pumped out through the joint leak into the soil outside the pipe.
5. The chemical grout displaces groundwater and saturates the soil
surrounding the pipe. After a period of time (usually less than a minute)
gelation of the chemical grout occurs, forming an impervious mass of seal-
ant outside the defective pipe joint. The packer is then deflated and moved
to the next joint.
Packer units may be obtained with a joint testing capability. Air is
used, with a drop in air pressure indicating the need to seal the joint.
Packers may also be obtained with an inflatable center section to assist in
pushing the grout out and minimize use of the grout.
A closed-circuit TV camera is used to remotely position the packer on
the pipe joints and to visibly inspect each joint prior to and after the
sealing operation. The TV camera and packer are pulled by cables through a
sewer section from manhole to manhole.
Internal grouting of pipe having minor bell shears and circumferential
beam breaks can generally be achieved provided that the packer sleeves in-
flate and seal against sound pipe on each side of the defect.
Leaking manhole walls, bases, troughs, and cracks in wet walls and lift
stations can be sealed under the proper conditions. Special techniques are
required which usually involve pumping chemical grout out through the leak
or drilling a hole for that purpose. This is often referred to as "struc-
tural waterproofing."
Acrylamide gel can be used to stop running water prior to cement grout,
gunite, or cement mortar application.
Leaks in building sewers can often be sealed with acrylamide gel.
Since access and size, usually 4 in. diameter (10 cm) prevent the use of
conventional camera packer procedures, special techniques are used.
Frequently, the entire building sewer is pumped full of grout causing
exfiltration of grout through the various leaks. After gelation, it is
necessary to clean the excess grout frcui the building sewer with a rodding
machine.
Manhole to external drops can be sealed by methods similar to those
described for building sewers.
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Criteria for Proper Application of Grouts
o Adequate structural integrity must exist in the pipe or structure
considered for sealing
o Soil conditions surrounding the pipe or structure should allow
for effective sealing
o Pipe must be thoroughly clean to permit proper operation of a
sealing packer
o Pipe must be free of obstructions and intruding service connections
to permit passage of the sealing packer through the pipe lines.
Acrylamide grout should not be subjected to prolonged dry soil condi-
tions or exposure to dry air. Resistance to dehydration can be achieved by
using an admix of 10 percent calcium chloride flake in the grout formulation.
Technique Advantages
o Most leaks in manually accessible pipe or structures can be
sealed, using special equipment and methods when necessary
o Acrylamide grout is an effective method of sealing leaks in pipe
joints. (The seal has a high degree of flexibility and therefore
sealed joints can accept movement).
o Sealing creates an impervious mass outside the joint by saturating
and stabilizing the backfill, therefore, continued movement of
improperly supported pipe may be arrested
o Leaks in building sewers, manhole external drops and stubouts can
usually be sealed with increased quantities of acrylamide gel
o Low viscosity chemical grout can penetrate small cracks for struc-
tural sealing against high pressures
o Variable and controllable gel time is useful in penetrating large
distances for structural waterproofing
• o Acrylamide gel is easy to clean up. Gel left in sewer pipe will
be macerated at pumping stations.
Urethane Foam
Urethane foam is a liquid prepolymer containing solid materials
constituting 82-88 percent of its weight and having a viscosity in the
300-350 centipoise range. When mixed with an equal quantity of water con-
taining an accelerator (0.4 percent concentration), the hydrophilic polymer
initially foams and then cures to a flexible cellular "rubber."
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When the prepolymer reacts with water, foaming and expansion commences
with steadily increasing viscosity. After a period of time (foam time) the
grout is forced into the leakage site while it has sufficient mobility to
penetrate the leak, but will not readily flow out of the site into the
surrounding soil or washed-out cavity beyond. Foam time ranges from 45
seconds at 40°F (4°C) to 15 seconds at 100°F (38°C).
After the grout is forced into the leakage site (end of foam time),
cure time begins. During this period, the grout solidifies and forms a
cellular rubber-like material of sufficient strength to become a barrier
against water.
Temperature of the grout and water is the variable that affects cure
time. Cure time ranges from 15 minutes at 40°F (4°C) to 4.6 minutes at
100°F (38°C), when reacted by water only. Cure time ranges from 5.5 minutes
at 40°F (4°C) to 2.6 minutes at 100°F (38°C), when reacted by water with
0.4 percent accelerator.
When cured, urethane foam is held in place at the leak site by a
combination of chemical and mechanical adhesion. Physical properties of
the cured material depend on the degree of confinement during the cure
period. Density of 14 lbs/ft3 (224.3 kg/m3), tensile strength of 80-90 psi
(5-6 kgf/cm^), and elongation of 700-800 percent for the cured material are
published by the manufacturer. The cured material is resistant to most
organic solvents, mild acids and alkali.
Wet or dry cyclic conditions do not substantially affect the grout due
to the fact that it contains only 15 percent solvent in the prepolymer, and
when fully cured and dry will likewise suffer a linear shrinkage of only
15 percent. Shrinkage has little effect on the gasket formed because of
adhesion to the joint/leak interface.
Urethane foam grout has an application history dating from 1970.
Internal grouting of structurally sound pipe joints is the most widely
used application. Pipe joint sealing is accomplished with a packer which is
basically described and operated as follows:
Placement;
1. A hollow metal cylinder having inflatable rubber sleeves at each
end and in the center is positioned on a pipe joint or other defect point.
The three inflatable sleeves are covered by a continuous outer sleeve to
which the grout will adhere. Figure 4 shows a typical grouting unit.
2. Air pressure is introduced underneath the end sleeves, causing
them to expand and seal against the internal pipe wall on each side of the
joint to be sealed.
3. A quantity of prepolymer and water is injected (and mixed) into
the void created between the two inflated packer end portions and "foam
time" begins.
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Source: Cherne Industrial, Inc.
Figure 4. Sleeve packer for use with 3M Elastomeric grout.
4. At the end of foam time (35 seconds at 60°F (17°C)) the center
element is expanded against the joint, forcing the grout into the joint/
leak and "cure time" begins.
5. At the end of cure time (4 minutes at 60°F (17°C)) the grout has
developed sufficient strength to become a barrier against water. The packer
is then deflated and moved to the next joint. Packer units may be obtained
with a joint testing capability. Water is used as the pressure medium.
Loss of water indicates a need to seal the joint.
A closed-circuit TV camera is used to remotely position the packer on
the pipe joints and to visibly inspect each joint prior to and after the
sealing operation. The TV camera and packer are pulled by cables through
a sewer section from manhole to manhole.
Internal grouting of pipe having minor bell shears and circumferential
beam breaks can generally be achieved, provided that the packer sleeves
inflate and seal against sound pipe surfaces on each side of the defect.
Leaking manhole walls, bases, and troughs can be sealed under proper
conditions. Special techniques are required which usually involve injecting
the grout into the leak.
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Criteria for Proper Application
o Adequate structural integrity must exist in pipe or structure
considered for sealing
o Soil surrounding the pipe must have adequate stability to support
the pipe after the joints or other defects are sealed
o Pipe joints or cracks must have adequate space for mechanical
retention of applied sealant
o Pipe must be thoroughly clean to permit proper operation of a
sealing packer. Roots and sand must be removed prior to sealing.
o Pipe must be free of obstructions and intruding .service connections
to permit passage of the sealing packer through the pipe line.
Technique Advantages
o Urethane foam can be an effective method for sealing leaks in
pipe joints
o The grout can be effective in both wet and dry conditions
o The grout has a high degree of flexibility and can thus accept
movement
o The grout is not sensitive to backfill conditions.
Grouting of Manually Accessible Pipe
Manually accessible pipe can be sealed using either sealant with the
use of appropriate equipment. The sealing equipment is set up directly
over the joint for small diameter pipes. For larger pipes and manholes
holes are drilled in the pipe wall and the grout is injected.
Internal grouting of manually accessible pipe using epoxy for the
purpose of adding strength to the existing structure can be used. (1)
A hydraulic cement is applied to the crack or joint to temporarily stop
the intrusion of water. Into this hydraulic cement are placed T-type
orifices that will allow later entry of the two-part epoxy resins.
After the curing of the hydraulic cement is complete (usually a few
seconds to a few minutes), a two-component, 100 percent solid epoxy paste
is applied over the hydraulic cement. This paste has gel time of 15
minutes to one hour, depending upon temperature.
These relatively new epoxies contain both mechanical and thermal curing
properties and are non-toxic in their mixed form, eliminating the need for
special ventilating equipment.
52
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After the epoxy paste has cured, water will only enter the structure
through the inserted orifices. At this point, an epoxy pumping system is
used to inject resin through the T orifices. The resin must he injected
at 28 to 29 psig (1 to 1.4 kgf/cm ) greater pressure than the intruding
water, and into the joint or crac^. The injection resin has a cure time
of approximately 45 minutes at 55 F (13 C) and one hour at 32 F (0 C).
This does not appear to be a limiting factor because water will not displace
the non-cured epoxy nor will it become soluble, even at the highest
temperatures encountered.
The operator of the pumping equipment can avoid filling large voids on
the outside of the structure by simply reading back pressure on the gauges
affixed to the pumping equipment.
The cured epoxy (100 percent solid material) remains exactly in the
form in which it was injected. There is no shrinkage or expansion of the
material.(l)
Pipe Lining
Several factors are applicable to both polyethylene and glass reinforced
polyester mortar pipe lining and systems. These are:
Applicability
o Extensively cracked pipe
o When excavation/replacement is intolerably inconvenient
or impractical
o When the existing pipe cannot be taken out of service or
bypassed during rehabilitation.
Criteria for Proper Application
o Prior to a decision on the applicability of rehabilitation, the
existing pipe must be internally inspected to ascertain structural
conditions, obstructions, offset joints, intruding service con-
nections, line and grade. A proofing tool, preferably a rigid
nose cone of sufficient size and length, should be pulled through
the existing pipe to prove the feasibility of inserting the
proposed liner diameter.
o The existing pipe must be in good enough condition to allow
cleaning prior to lining.
o Generally, slip-lining is most feasible when a considerable length
(2 or 3 manhole sections) can be lined from a single excavation.
When more than two excavations are required in a manhole section,
replacement of the section is usually indicated.
53
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Technique Advantages
o Normal sewage flow can be maintained during liner insertion.
o Liners are corrosion resistant.
Technique Limitations
o Cleanliness, condition and alignment of existing pipe are
critical considerations.
o Building sewers are difficult to cut in and connect.
1. Polyethylene;
Insertion lining of existing sewers with polyethylene pipe is performed
by pulling a continuous length of butt fused liner pipe into an existing
sewer through an. excavation point. The excavation is made directly over
the existing line and has sufficient width to allow the entry of workmen.
Sheathing and bracing requirements depend on depth and ground conditions.
The length of the excavation is determined by the depth of the sewer and
the bending radius of the sewer liner pipe. The bending radius is usually
30-50 times the outside diameter of the liner pipe. The selection of the
radius is based on the need to avoid kinking of the liner pipe and to reduce
frictional forces at the entrance of the existing sewer. The trench is
sloped gradually from the ground surface to the top of the existing line.
Excavations are chosen at points where a dig up is indicated and/or where
the longest pull can be made in each direction from a single trench.
A winch of sufficient power is used to pull the liner into the
existing pipe from as far away as practical. Usually there is sufficient
annular clearance around the liner to permit normal sewage flow during
installation without need for bypassing or disrupting service on the line.
Building sewers, if any, must be cut in and connected in a manner which
will prevent infiltrating groundwater in the annulus from entering the
liner at the service taps. This is achieved either by directly connecting
the building sewers to the liner or by grouting the annulus using techniques
which prevent grout from entering the liner pipe and the building sewer.
Grouting the annulus for structural support is generally not necessary
if the -liner wall thickness is strong enough to withstand anticipated loads
in the event of existing line collapse. When the annulus is not grouted, an
efficacious seal must be made at each manhole interface to prevent ground-
water entry.
Applicability
Polyethylene line rehabilitation is applicable for:
54
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o Steadily deteriorating sewer pipe such as lines having shallow
grades, septic conditions and corrosive liquids
o Lines in unstable soil conditions
o Pipes having massive and destructive root intrusions.
Criteria for Proper Application
o Liner, wall thickness must be chosen to withstand anticipated
external hydraulic loads and trench loads in case the existing
pipe collapses. The impact and advisability of annulus grouting
influence the wall thickness determination.
o The influence of cold weather on liner stiffness and thermal ex-
pansion/contraction must be considered when scheduling installation.
Technique Advantages
o The liner has widely spaced, 38 ft (11.6 m) heat-fusion joints
which prevent joint leakage and root intrusion
o The liner has a high flow factor which may increase the flow
capacity of the pipe line
o Since the liner is capable of deflection and movement without
breaking, it is an attractive method for rehabilitation of lines
laid in unstable soils when replacement would have doubtful
permanence
o Long lengths may be inserted
o Flexibility permits insertion through gradual changes of direction.
Technique Limitations
o Excavations must be large enough to provide adequate bend radius
(30 D) during installation. NOTE; If more than two excavations
are required in a manhole section, replacement of the section is
usually indicated.
2. Glass Reinforced Polyester Mortar;
Insertion lining of failing sewers with fiberglass reinforced plastic
mortar pipe is performed by jacking or drawing liner sections, usually
20 ft (6.1 m) into the existing pipe line. The liner sections are joined
by 0-ring sealed inverted bell and spigot joints which maintain a uniform
outside diameter.
An excavation is made directly over the existing line. The working
pit must be long enough to accommodate the sections of liner and the jack-
ing equipment. A pit of approximately 26 ft (7.9 m) can be used if the
liner sections are pulled into the existing line. Sheathing and bracing
55
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requirements depend on depth and ground conditions. The top half of the
existing pipe is removed in the working pit to permit insertion of the liner
sections. It is easier to pull the liner pipe upstream against the flow
because fragments lost during removal of the upper portion of the existing
pipe and debris from the access pit tend to get into the line and, due to
its light weight, the liner has a tendency to move with the flow, creating
the possibility of coming disjointed going downstream.
Normal sewage flow can continue during the entire procedure. Grouting
the annulus between liner and existing pipe is generally not necessary.
When the annulus is not grouted, an efficacious seal must be made at each
manhole interface to prevent groundwater entry.
Applications
o It is generally more applicable to large lines 21 in. (53 cm) and
up having no sevice connections.
Criteria for Proper Application
o Generally, lining is most feasible when a considerable length of
pipe can be lined from a downstream working pit.
Technique Advantages
o Reinforced plastic mortar pipe has high strength, and is
hydraulically smooth
° Working pit length requirements.are minimal.
Technique Limitations
o There is some flow reduction from inverted bell joints.
o Semi-rigid material has limited ultimate strain capability.
3. Cement Mortar and Epoxy Mortar
Cement and epoxy mortar linings can be centrifugally machine applied
to the interior surface of existing pipes. Lining thickness requirements
are dependent on the degree of deterioration. Thickness may range from a
minimum of 0.125 in. (0.3 cm) to a maximum of 0.75 in. (0.9 cm) for a
single pass of the lining machine. Figure 5 shows such an application.
Applications
Mortar lining is applicable to deteriorated round pipe which is
structurally sound. Mortar linings are most often applied to concrete
pipe, and sometimes applied to brick pipe..
56
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Cutting small diameter pipe prior to cleaning and
Small diameter machine
in action without trowels
Drag cleaning 6" pipe
Source: Raymond International, inc.
Figure 5. Application off cement mortar and epoxy mortar.
Cement mortar is generally used to rehabilitate sewer pipes 16 in.
(41 cm) in diameter or larger which have deteriorated from severe erosion
or from corrosion by chemical attack. It is not used to prevent corrosive
attack.
Epoxy mortar is mainly used to prevent deterioration of sewer pipes
24 in. (61 cm) in diameter or larger from,a corrosive atmosphere or acidic
flow. These conditions may be found in both domestic and industrial waste
lines. Epoxy may also be applied as a finish coat to cement mortar. The
materials must be carefully controlled and mixes adjusted for local condi-
tions such as temperature.
Criteria for Proper. Application
o Sewage flow must be by-passed and service suspended in the section
being lined. The pipe surface must be free of loose material and the surface
should be treated as necessary to remove traces of oil, scum, bacterial
growths, or other substances.
o Water standing in the pipe must be removed. Infiltration of any
type must be stopped prior to lining application.
o Damp pipe is permissible for both cement mortar and epoxy mortar
lining so long as water droplets or water films are not apparent on the pipe
surface.
o Ambient temperature must be greater than 50°F (10°C).
57
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Technique Advantages
o When used to rehabilitate deteriorated pipes or to prevent
future chemical attack, cement and epoxy mortar lining offers a
moderate cost alternate to replacement
o The technique involves minimal reduction of pipe diameter.
Technique Limitations
o Sewage flow must be by-passed and service suspended during
application
o Infiltration through pipe joints, pipe walls and building
sewers must be stopped prior to application
o Cement mortar alone should not be used to prevent chemical
attack
o Epoxy mortar should not be mixed or applied below 50° F (10° C).
Difficulty and Cost Factors which Affect Rehabilitation Operations
Rehabilitation difficulty factors are very complex. Every sewer
system deficiency and applicable rehabilitation technique is cost
sensitive to different considerations. Complex difficulty/cost factors
must be considered in any rehabilitation decision.
o Location of job determines equipment mobilization costs, local
labor rates and expense of crew accommodations.
o Weather conditions (cold temperature, rain, snow) have a
significant effect on production rates, not because of crew discomfort,
but for reasons such as: Inability to locate manholes under snow cover;
reduced mobility of vehicles and equipment; inability to park equipment
on street; inability to enter manholes because of high water flooding;
freezing, stiffening, and longer cure time of rehabilitation materials.
o Access to manholes, including locating and exposing them if
paved or covered over, as well as topography and terrain for vehicle and
equipment access are important cost factors.
o Manhole conditions, including size, clear opening, depth, steps,
inside/external drops, hazardous gas and cleanliness all affect re-
habilitation practices.
o Pipe size has a significant impact on certain rehabilitation
procedures. Small pipes 6 and 8 in. (15 and 20 cm) require heavier,
specialized equipment with clearance limitations. Intermediate pipes
10 to 21 in.(25 to 53 cm) are mostly sensitive to the increase in
materials consumption with size. Large pipes 24 to 36 in. (61 to 91
cm) also require heavy specialized equipment, and often necessitate
removal of the top portion of a manhole for access.
58
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o Depth and rate of flow, ability to plug the line, or the necessity
to by-pass flows are important considerations
o Cleanliness of the pipe and the rate of infiltration or washdown
of debris into the rehabilitation area determine the necessity for
additional cleaning
o Pipe conditions such as offset joints, intruding joint materials
such as cement and tar, intruding service connections, crushed pipe, or
other conditions which could prevent the passage of grouting equipment
and liners, or require reverse set-ups or excavations, are of critical
concern in determining rehabilitation costs
o Rehabilitation of successive sections is more efficient on a
unit basis than random section repairs due, to mobilization and set-up
expenses
ROOT CONTROL (A comprehensive discussion of root control is found in
"Economic Analysis, Root Control and Backwater Flow Control as Related
to I/I Control."
Purpose of Root Control/Removal
o To prevent root blockages
o To restore full capacities and self-scouring velocities
o To prevent destruction of pipe
o To prepare for rehabilitation procedures such as slip-lining,
mortar lining and internal grouting
o Reduction of septic conditions and hydrogen sulfide generation
can increase life expectancy for the pipe line.
Root control is a significant sewer maintenance function. Munici-
palities frequently have rodding machines engaged in unstopping root
blockages, often on an emergency rather than a preventive maintenance
basis. Thorough root removal is a requirement of adequate cleaning in
preparation for internal pipe inspection- and rehabilitation.
Background Information
Roots grow toward moisture by a continuous process (hydrotropism)
occurring at the very end of the root. One cell at a time is added at
the end of the root enabling it to penetrate extremely small openings in
the pursuit of moisture. Sewer pipes which are always below the ground-
water level do not have root intrusion because roots do not need to enter
the pipe to find water vapor. Tree roots are not hydrophylic and rarely
enter a sewer pipe below the water level within the pipe. They most often
enter shallow pipes which are above groundwater, or pipes which are
seasonally above the groundwater table.
59
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The ends of roots are composed of tender primary tissue. As a root
grows longer and larger, living tissue (phloem) exists near the surface.
Under the phloem is a thin formative layer(cambium) that gives rise to
new cells and is responsible for secondary growth. The center portion of
a root (xylem) constitutes the woody element which becomes stronger as the
root grows larger. When a root enters a sewer pipe joint, above the water
line, it is likely to grow larger on both sides of the hole through which
it came until the hole is effectively sealed. The woody xylem contains
parenchyma cells which are capable of dividing even when mature and may
eventually exert sufficient force to break the pipe.
After a root enters sewer pipe, it may divide hundreds of times to
form an enormous mass of tender root ends. The root mass usually collects
a thick coating of grease, becomes heavy and hangs into the water causing
grit settlement and shoaling. Debris and sewage solids continue to pile
up on the root mass until a blockage occurs.
A typical emergency response to a sewer line blockage is to rod the
line using an auger tool. The blockage will be relieved and a clump of
roots is likely to be pulled out of the line. Unfortunately, much of the
root mass will probably remain. The remaining roots respond to their
injuries by producing traumatic acid in order to hasten and thicken their
regrowth.
In low water table areas, trees such as camphor and willow can produce
shallow distant roots reaching 30 feet beyond their branches.
Prevention
Pipes constructed with watertight durable joints are unlikely to have
root intrusion. Unfortunately, less emphasis is placed on the tightness
of pipe joints when the pipe is above the groundwater level than when
infiltration would occur.
Effectiveness of Root Control; The effectiveness of root control procedures
has been evaluated on the basis of how often control measures were required
to prevent line stoppage. The general location of the roots can be
determined when mechanical tools are used, hut not whether Or not the roots
are from a joint or house lateral.
An evaluational root control procedure utilizing internal inspection
(TV) can provide guidance for the development of a comprehensive program.
Each joint with roots should be identified and the amount of root growth
at the joint classified. Root growth should be rated from one to nine
with ten representing a complete screen of roots.
The camera operator should be furnished with a set of photos
representing varations in root growth. Figure 6 is such a training tool
developed by the Sacramento County Department of Public Works.
60
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61
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Root control programs are not a permanent, one time operation. .The
conditions which allow a root to enter the pipe are not changed by the
root control program. Thus roots may continue to grow or new roots intrude.
Use of the visual evaluation technique on control sections of the sewer
system allows decisions as to cost-effectiveness of removal technique and
the frequency with which maintenance operations should be repeated.
1. Mechanical Removal
When root blockages occur, mechanical removal provides the only
immediate relief. Mechanical removal is usually performed by rodding
machines, bucket machines, or hard winches using a variety of end tools
such as augers, root saws, buckets, scrapers, porcupines, brushes and
squeegees. High velocity jet machines can use special root cutting tools
although their applicability is generally limited to moderate root growth
,in 8, 10, and 12 in. (20, 25, and 30 cm) pipes.
Partial root removal encourages regrowth. If, however, the roots are
completely removed and cut off flush at the pipe wall, a considerable
length of time will be required for regrowth. Woody root xylem will fill
up much of the hole through which the root originally came. New growth
must come from the relatively thin cambium surrounding the xylem.
Full gauge cleaning tools are required for complete root removal,
however, they cannot always be used due to the presence of intruding
service connections and badly offset joints.
Mechanical cleaning of roots generally leaves a part of the root intact
hastening regrowth. Television inspection following cleaning by a
variety of root cutting tools has shown this to be a general case. The
presence of roots extending out into pipe from the joint is particularly a
problem if the urethane foam grout is to be used as the grout will adhere
to the root and possibly obstruct flow or hinder future cleaning operations.
2. Copper Sulfate
An early method for chemical control of roots in sewer lines was to
place several pounds of copper sulfate periodically in manholes upstream
of troubled sections. This method of root treatment allows no control
over concentration of poison or duration of exposure. Tests by Ahrens,
Leonard, and Townley (2) using very high concentrations of copper sulfate
(10,000 mg/1) for one hour caused systemic injury without completely killing
roots.
Unfortunately, copper absorbed by roots killed with copper sulfate is
also poisonous to bacteria and fungi which would normally decompose the
dead roots.
3. Herbicides
A comprehensive study of numerous herbicides was made by Ahrens,
62
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Leonard, and Townley (2). Herbicides tested in their root control experi-
ments are given in Table 2.
In the screening tests, roots not only were consistently killed with
dichlobenil at 100 mg/1, but also regrowth above the point of treatment
was inhibited. Because of its known safety and use as an aquatic herbi-
cide and its toxicity to roots at low concentrations, dichlobenil seemed
to be a good candidate herbicide for further studies. (2)
A combination of metham at 500 mg/1 and dichlobenil at 10 mg/1
completely killed eucalyptus roots with negligible foliage injury. These
results formed the basis for more intensive study with metham and
dichlobenil to determine the importance of factors that might affect root
kill and systemic movement of metham to foliage. (2)
Experiments in sewer lines showed that flood treatment with
dichlobenil and metham can effectively kill tree roots. Dichlobenil is an
effective inhibitor of root growth even at sublethal concentrations, and
metham has the ability to kill roots for a distance above the point of
contact. In combination, they achieve immediate root kill and a deterrent
to regrowth.
Flood treatment permits control of herbicide concentration and
contact time during application. The chief advantage of flood treatment
over spraying or foaming is that it assured penetration of root-infested
joints and.may allow some exfiltration and killing of roots outside the
pipe.
Extensive field testing of dichlobenil and metham has been performed
by the County of Sacramento and is reported by Townley(3). Pursuant to
preliminary tests, large scale field applications were undertaken using
a concentration of roughly 3,000 mg/1 metham and 200 mg/1 dichlobenil plus
wetting agent. It should be noted that the water solubility of dichlobenil
is low (about 18 mg/1). The use of 200 mg/1 merely assures that the
treating solution is saturated with dichlobenil.
In part, Townley concludes:
"Our field applications have provided excellent results.
A root kill of at least 50 percent is the normal minimun.
Our average kill is about 75 percent. To achieve these
results careful attention must, be given to application
procedures o ^ Chemical concentration and contact time are
absolutely essential to effective treatment. Careless
application can only result in unsatisfactory results.
These herbicides cannot be effectively applied by simple
flushing down a commode or simple pouring into sewage
flow from an available manhole. The chemical must be
thoroughly mixed with the solution water and held in
positive contact with root growth for one hour."
63
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Flooding cannot be used in many areas due to topography. During the
past year, several local authorities have successfully utilized the
herbicide in the form of foam. When applied to a sewer, a plastic hose
is inserted to about the center of the reach and then retrieved, filling
the pipe with foam. Others have foamed the entire line,, not retrieving
the line until foam appears at the downstream manhole.
Action of the sewage in the line appears to keep the foam at the
top and sides of the pipe where it can come in contact with roots.
Foam can also be used to treat house connections. Entrance to
the property is blocked and then the foam is allowed to fill the sewer
connection.
Cleaning to Remove Roots: After a period of six to twenty weeks,
the roots in the sewer will either fall off or break at the sewer wall
when a rod or hydraulic cleaner is used. New or regrowth appears to
be minimized.
Chemical Grout and Admixtures: The toxicity of acrylamide grout,
acrylamide grout fortified with metham, and acrylamide grout fortified
with dichlobenil was evaluated by Ahrens (4):
"Metham increased the gel time, requiring a higher
concentration of catalyst, but dichlobenil did not
effect gel time. The standard gel killed most of
the treated apple root sections whereas the
fortified gels killed all treated root sections.
Roots were killed further above the treated section
with metham or dichlobenil than with standard
grouting materials. In time, branch roots developed
normally above root sections killed with all gels.
Willow roots penetrated sand gels formed by the
standard or metham fortified grouting materials but
did not penetrate the gels fortified with
dichlobenil."
Formulations of the root control chemicals with a USEPA approval
number are marketed by the Airrigation Engineering Company, Inc., Carmel
Valley, 'California.
Acrylamide grout containing dichlobenil is available as AM-9.plus.
Urethane grout containing a root growth inhibitor in the formulation is
also available.
4. Scalding Water Flooding
Scalding water will kill tree roots regardless of transpiration rate,
without damage to foliage or ill effects on treatment processes (5).
65
-------
Enzymes start to lose their catalytic properties at 95 F (35 C)
and are completely denatured at 140 F (60 C). Denaturation by
temperature is more general and efficient (than poison) because it is
able to break those disulfide bonds which are deeply buried within the
protein molecule and shielded from heavy metal attack. Once
denaturation has taken place it is almost always irreversible. A
temperature of 122° F (50° C) will kill most plant tissue; 140 F (60 C)
will kill almost all living tissue. Somewhat higher temperatures will
break down root cell walls of the phloem causing physical damage and
accelerated decomposition by attack from bacteria and fungus„ Contact
time depends upon the diameter of the root, i.e. time to heat the root.
Penetryn has reported that a full scale test using a three million
BTU/hr boiler (private correspondence received from Penetryn, May, 1975)
was able to maintain the proper temperature by controlling the rexease
rate of the impounded water. Cost-effectiveness data are not yet available.
COST DATA. DEVELOPMENT
Cleaning Costs
It is important for the investigator of sewer system infiltration/
inflow conditions to recognize those factors which will most affect the
cleaning of sewer lines if a true understanding of the subject problem
is to be achieved. Although these factors are rather complex and
interrelated, they can generally be divided into two basic categories:
(1) sewer cleaning difficulty factors; and (2) labor cost factors.
As the task of cleaning sewer lines is labor-intensive, representing
between 25 and 35 percent of the daily operating cost; the cost,
productivity, availability and restrictions of the labor force is a s.ign*-
ficant determining factor in the ultimate cost for performing sewer
cleaning tasks.
Therefore, equivalent work in major metropolitan areas will undoubt-
edly be more costly than work in a rural area. Likewise, cleaning of
sewer lines in the northern areas will generally be more costly than
work performed in the southern portions of the United States.
Of equal, if not greater, importance to the cost of sewer cleaning
is an understanding of cleaning difficulty factors. These factors will
determine the selection of equipment to be used, the size of the cleaning
crew required, and the rates of productivity which can be achieved. They
all affect the total cost.
Some of the significant factors associated with sewer cleaning are
shown in Table 3.
To demonstrate the effects of varying difficulty factors, as they
relate to overall sewer cleaning cost, two examples of performing a
single basic task are presented.
66
-------
From the examples the effects of change in difficulty factors can
easily be seen. In Example 1, where both manholes are easily accessible
by large trucks and water is available at the site, a jet cleaner could
be used, requiring only a three-man crew with an anticipated productivity
rate of 700 ft (213 m) per day. However, in Example 2, where neither
manhole access nor water is available, the bucket machine cleaning process
was selected, requiring a four-man crew with an anticipated production
rate of only 300 ft (91 m) per day..
TABLE 3. SEWER CLEANING DIFFICULTY/COST FACTORS
Access to Manholes
Condition of Manholes
Type of Manhole Construction
Size of Manholes
Depth of Sewer Lines
Depth of Flow In Sewer
Type of Deposition in Sewer
Size of Sewer to be Cleaned
Structural Condition of
Sewer to be Cleaned
Length of Manhole Section
Intruding Building Sewers
Requirement for Transportation
and Disposal of Material Removed
from the Sewer
Distance to Disposal Site
Traffic Control Required
Availability of Water
Degree of Root Intrusion
Successive Manhole Section
versus Random Section Cleaning
Weather Conditions
67
-------
EXAMPLES 1 AND 2
Definition of Task
Clean 8 in. (20 cm) diameter sanitary sewer line
Type of pipe - clay
Amount of debris - 1/3 full, or 2.7 in. (6.5 cm)
Type of debris - heavy sand
Length of manhole section - 300 ft (91 m)
Depth of line - 6 ft (1.8 m)
Amount of flow - 20 percent of capacity
Factor
a) Traffic Control
b) Access Manholes
c) Water
Selection of Equipment
Crew Size Required
Production Rate/day
Example 1
- Not required
- Both manholes
available
- Available at
site
- Jet cleaner
- Three men
- 700 ft (213 m)
Example 2
- Not required
- Minimum access
- Not required
- Bucket machines
- Four men
- 300 ft (91 m)
As can be seen, broad-based differences can be incurred in the cost of
sewer cleaning depending on many varying and interrelated factors, such
as access. The difficulty factor differences between cleaning sewers
located under streets versus cleaning sewers located in ravines with no
vehicular access are extreme. In order to develop an accurate estimate of
expected cleaning cost, each element (cleaning difficulty factors - labor
costs) should be identified, defined, and assessed with respect to its
influence on the selection of equipment, crew size required, and anticipated
productivity accomplishments.Once the specific area of work has been
selected, such as the particular manhole sections, then qualified sewer
cleaning contractors may be contacted to assist in the assessment of the
difficulty factors and provide experienced judgement regarding equipment
selection, anticipated productivity rates and probable cost ranges.
Figure 7 gives cost data based on specific assumptions and the change
relationship which occurs with changing difficulty factors or changing
labor cost factors. The assumptions established for the example, as
identified in Figure 7 are as follows:
68
-------
Access to Manholes
Condition of Manholes
Type of Manhole Construction
Size of Manholes
Depth of Sewer Line
Depth of Flow in Sewer
Depth of Deposition in
Sewer
Size of Sewer to be Cleaned
Length of Manhole Section
Requirements for Trans-
portation and Disposal
of Materials Removed
from the Sewer
Traffic Control
Availability of Water
Degree of Root Intrusioii
Successive Manhole Sections
Both manholes are located in
paved streets and readily acces-
sible to all types of cleaning
equipment.
Both manholes are structurally
sound and have steps for personnel
access.
Manholes are constructed with
precast concrete.
Manholes are 4 ft (1.2 m) diameter,
with minimum opening through the
manhole cover frame of 21 in.
(53 cm).
Average 6 ft (1.8 m) depth.
20 percent of pipe diameter.
25 percent of pipe diameter.
- 6 in. (15 cm) through 36 in.
(91 cm).
- 350 ft (107 m)
- Disposal area is approximately
3 mi (5 km) from the work site
and accessible via non-congested
paved roadway.
- No barricades or uniformed traffic
control are required.
- Flashing beacons on vehicles are
sufficient.
- Water is available from fire
hydrants throughout the work area.
- None.
- All cleaning required is in suc-
cessive manhole sections.
69
-------
$/m $/ft
-1
_ra
1
c
22.14
21.32
20.50
19.65
18.84
18.04
17.32
16.00
15.58
14.70
13.80
13.12
12.30
11.45
10.65
9.84
9.02
8.20
7.38
6.56
5.72
4.92
4.10
3.28
2.46
1.64
0.82
Inspection
6.75-
6.50-
6.25'
6.00 •
5.75-
5.50-
5.25
5.00-
4.75
4.50
4.25
4.00-
3.75-
3.50-
3.25-
3.00 •
2.75;
2.50~,
2.25.
2.00
1.75
1.50
1.25
1.00
0.75,
0.50
0.25,
INCREASED LABOR COST AND DIFFICULTY FACTORS
BASED ON EXAMPLE
DECREASED LABOR COSTS AND DIFFICULTY FACTORS
6
15
8 10 12 15 18 21 24 30
20 25 30.5 38 45.1 53 61 76
Pipe Sizes
Figure 7. Basic cleaning cost data.
36
91
inches
cm
For the purpose of this section, references to internal pipe
inspection, pipe inspection or inspection include closed-circuit television
or photographic procedures. Though the methods and results are different,
the costs of the two procedures are about the same.
As with sewer cleaning, internal pipe inspection is a labor-intensive
task. Material costs, such as photographic film and video tape are small
in comparison to cost of supervision, technician services and labor. There-
fore, labor availability, skill availability, productivity of the labor
force and labor cost have a significant influence on total inspection costs.
Significant inspection factors are shown in Table 4. Such factors
influence the cost of inspection due to crew size, crew skill requirements,
productivity rates or need for special or auxiliary equipment.
70
-------
TABLE 4. INSPECTION DIFFICULTY/COST FACTORS
Length of Manhole Section
Access to Manholes
Terrain
Traffic Control Require-
ments
Manhole Conditions
Depth of Sewer Line
Depth of Flow
Flow Rate
Flooding Conditions
Plugging Requirements
By-pass Requirements
Pipe Size
Pipe Cleanliness
Presence of Combustibles
Pipe Structural Conditions
Weather
Random vs. Successive Sections
Documentation Requirements
Report Requirement
Another element and/or requirement that will have a major impact
on cost of the inspection task is the nature of the reporting requirement.
In some instances, filing of bound copies of the field report and field
recordings is sufficient; in other cases a complete engineering report,
including voluminous information not ordinarily collected during the inspec-
tion task, is required and extensive analyses of this information must be
furnished. These requirements would not only increase the cost, but would
also increase the technical skills required to perform the inspection and
require expensive engineering capability in the field during the performance
of the task.
In determining what costs might be involved in an inspection project,
each of the factors discussed should be considered and assessed as to their
probable impact. In addition, a well defined objective with required results
should also be indicated. Assistance in developing expected cost data may
also be sought from one of the many reputable inspection firms around the
country.
Basic inspection costs are presented in Figure 8, which provides
ranges reflecting the most common combinations of difficulty factors,
labor cost and technical/report requirements. The "example cost" shown
is based on the criteria established by the following example using 1974
average labor costs.
EXAMPLE 3
a) General Requirements--
Inspect a system for physical integrity and condition prior to a ,
street paving program. Typed copies of the field inspection log sheets,
accompanied by a minimum number of photographs showing representative
findings, constitutes the report requirements. No engineering analysis,
71
-------
I
OJ
$/m $/ft
7.38 2.25-
6.56 2.00.
5.74 1.75.
4.92 1.50
4.10 1.25
£ 3.25 1.00.
O.
= 2.46 0.75,
o
Q
•£ 1.64 0.50,
O
0.82 0.25,
INCREASED LABOR COST AND
DIFFICULTY FACTORS
COST BASED ON EXAMPLE
"*«
i.
..«*»*'
DECREASED LABOR COSTS AND DIFFICULTY FACTORS
i i i i i i i i
6
15
8
20
10
25
12
30
15 18
38 45
Pipe Size
21
53
24
61
30
76
36
91
Figure 8. Internal pipe inspection cost data.
flooding of storm sewers during the inspection, or other auxiliary
activities are necessary.
b) Specific Site Conditions--
Mobilization Distance
Length of Manhole Section
Manhole Location
Traffic Control
Manhole Conditions
Depth of Flow
inches
cm
- 10 mi (16.1 km)
- 375 linear ft (114 m)
- Both manholes are located in
paved streets and readily
accessible to all required
equipment.
- None required.
- Both manholes are structurally
sound and have steps for personnel
access.
- Less than 20 percent of pipe
diameter.
72
-------
[b) continued]
Depth of Sewer Line
Plugging Requirements
By-pass Requirements
Pipe Size
Pipe Cleanliness
Presence of Combustibles
Weather
Successive Sections
- 6 to 8 ft (1.8 to 2.4 m)
- None
- None
- 6 in. to 36 in. (15 cm to 91 cm)
- Satisfactory
- None
- Summer day with no rain
- All inspection required is in
successive manhole sections.
Protruding Service Taps - None anticipated
COST DATA DEVELOPMENT - (Sanitary Sewers Only)
Smoke Testing
Smoke testing is primarily used to detect points of inflow during
favorable groundwater and weather conditions. Although seemingly simple,
smoke testing should be performed by experienced people who are aware of
what it does not reveal as well as what it does. Effectiveness of smoke
tests is dependent on thorough decumentation of findings, including
description of smoke leaks, numbered photographs and maps showing locations
of leaks with adequate measurements.
Smoke test equipment requirements are minimal. Costs are relatively
unaffected by pipe size except for an exponential increase in smoke
consumption in larger pipes. Unit costs are mostly sensitive to location,
such as downtown vs. residential areas and number of leak points detected
and documented.
The following unit costs are for performing smoke testing and supplying
copies of field reports. These costs are exclusive of the required public
relations efforts, including notification of fire departments and homeowners
and handling complaints. The costs do not include detailed analysis and
specific recommendations for remedial action.
Sanitary Sewer Smoke Testing Cost Data
Pipe Size
6-15 in. (15-38 cm)
18-36 in. (46-91 cm)
Note:
Cost Per Foot
Cost Per Meter
$ 0.15 to $ 0.25 $ 0.49 - $ 0.82
$ 0.20 to $ 0.30 $ 0.65 - $ 0.98
The above costs are based on 1974 labor and material costs,
and would not necessarily include a complete engineering
analysis report.
73
-------
Manhole Rehabilitation Costs
Manhole rehabilitation cost estimates require an understanding and
evaluation of numerous interrelated factors. These include type of manhole
construction; type, cause, and extent of failures; depth of manhole; type
of soil surrounding the manhole; manhole location; selection of the rehabili-
tation techniques; selection of rehabilitation materials, etc. A list of
possible manhole rehabilitation techniques is provided.
Rehabilitation Techniques:
Internal Cement Grouting by Pressure Injection
Internal Chemical Sealant Grouting by Pressure Injection
External Chemical Sealant Grouting by Soil Injection
External Cement Grouting by Soil Injection
Internal Epoxy Mortar Resurfacing
Internal Cement Mortar Resurfacing or Guniting
Mortar Joint Replacement by Pressure Injection
"External Drop" Sealing
Resetting and Resealing of Manhole Frames
Each of the above techniques may be utilized separately or combined in
various manners depending on manhole condition and the extent, type and
nature of rehabilitation required. The obvious difficulty is in
determining which technique or combination of techniques will be required.
The selection is generally dictated by type of manhole construction in
conjunction with the nature of the physical failure involved.
EXAMPLE 4
A) Basic Problem:
Manhole is structurally sound. The corbel section and base are in good
condition. Infiltration through the walls is significant.
B)
Type of Manhole Construction:
Manhole A
Precast Base
Precast Walls
Brick and Plaster Corbel
48 in. (1.2 m) Diameter
Manhole B
Precast Base
Brick and Mortar Walls
Brick and Mortar Corbel
48 in. (1.2 m) Diameter
C)
Selection of Rehabilitation Technique:
Manhole A - Infiltration can be contained within the small area
74
-------
between segments, therefore, internal chemical grouting or sealing would be
selected for use because oft
o
o
o
o
Ease of developing entry into the leakage source
. Minimum quantities of chemical grouting materials required
Minimum risks of renewed infiltration in other areas of the manhole
Work accomplished at one time with a single crew and set-up.
Manhole B - The leakage will not be well defined and cannot be
contained within a small wall section area. Its entry is through the mortar
joints. The sealing of the obvious points of infiltration would merely
divert the flow of water to other weak mortar joints where it would again
enter the manhole. With these conditions prevalent a combination of three
techniques would be selected? Mortar joint replacement by pressure injection;
internal epoxy or cement resurfacing; and internal chemical grouting. With
the above technique selected, timing would become critical because the
first two procedures should be carried out during "dry" conditions, while
the last would be done during periods of maximum groundwater levels.
As the example indicates, the cost of manhole restoration is dependent
upon type of manhole construction; nature and extent of the failure; and
type of rehabilitation technique or combination of techniques required to
effect the proper repair.
Table 5 provides basic understanding of the rehabilitation task cost
impacts. It is not the intent of this presentation to establish cost ranges
for estimating purposes. Unlike other activities discussed in this section,
manhole rehabilitation costs are comprised of almost equal proportions of
labor costs and material costs. Therefore, material selections and material
costs markedly affect the total cost and make it impossible to establish
fixed and/or predictable cost ranges.
The cost data, as shown in Table 5 are based on 1974 real cost data
for labor, supervision, materials, and the following set of basic example
criteria:
Access
Depth of Manhole
Diameter of MH
Depth of Flow
Combustible Gases
- Manhole located in paved street
- 6 ft (1.8 m) to 8 ft (2.4 m)
- 4 ft (1.2 m)
- 20 to 25 percent of pipe diameter
- None present
Sewer Line Grouting
The cost information presented covers only internally applied
chemical grouts, either Acrylamide Gel or Urethane Foam Grout. Though
there are other techniques and materials which have been used over the
years for sewer line grouting, little is known of either their successes
75
-------
TABLE 5. BASIC MANHOLE REHABILITATION TASKS AND COST RELATIONSHIP
Basic
Rehabilitation
Task
Reset and Seal
Manhole Frame
Chemical Grouting —
Base Only
Chemical Grouting —
Walls Only
Plaster and
Seal Walls
Joint Replacement
w/ Pressure Injection
Cement Grouting —
Base Only
Cement Grouting —
Walls Only
Chemically Grout
External "Drops"
TYPE OF MANHOLE CONSTRUCTION
Brick and
Mortar
X
X
X
X
X
X
X
Brick and
Mortar
w/ Plaster
X
X
X
X
X
X
Concrete
Block and
Mortar
X
X
X
X
X
X
X
Pre-Cast
or Cast
in Place
X
X
X
X
X
X
Minimum
Cost Range
$100.00-$1 50.00
$ 75.00-$1 25.00
$150.00-$ 125.00
$1 80.00-$! 97.00/vertical meter
($ 55.00-$ 60.00/vertical foot)
$13l.00-$164.00/vertical meter
($ 40.00-$ 50.00/vertical foot)
$150.00-$1 75.00
$250.00-$500.00
$150.00-$250.00
Noto: Tha success In manhole rehabilitation depends on —
1. Verifying that the manhole condition and environment allows rehabilitation
2. If grouting Is being considered — that the soil is groutable
3. That tha proper selection of rehabilitation techniques is made and that the tasks are performed in proper sequence.
or relative costs. As described in this section, the techniques for
applying the two sealants are similar as are the requirements for
personnel and equipment. This makes the cost, other than for material,
comparable. The material costs vary considerably, with Urethane Foam
Grout costing approximately twenty times that of Acrylamide Gel in
equal quantities. In application, however, these costs become almost
equal due to the smaller quantities of the former material required.
The operating costs of internal sewer line grouting are comprised
of two major elements: (1) Labor and supervision; and (2) the grouting
materials (base chemical components plus additives), with the materials
representing between 15 and 25 percent of the total operating costs.
Therefore, not only do the factors shown in Table 6 affect costs but the
material cost, transportation cost, and quantities of materials required
also have significant impact on the total costs. The difficulty factors
dictate the crew sizes, equipment and rate of productivity in the
grouting operations.
In order to present some relative cost data, certain basic exclusions
were made in the example calculations shown in Figures 9 through 13.
a) No cost calculations are included for any by-passing of sewage
flow around the manhole section during the grouting operation.
76
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TABLE 6. SEWER LINE GROUTING DIFFICULTY/COST FACTORS
Mobilization Distance
Weather Conditions
Access to Manholes
Terrain
Type of Soil
Manhole Opening
Manhole Size
Manhole Cleanliness
Manhole Depth
Type of Pipe
Pipe Alignment
Pipe Grade
Pipe Cleanliness
Depth of Flow
Flow Rate
Ability to Plug
Hazardous Gas
Type of Joint
Joint Spacing
Offset Joints
Protruding Service
Connections
Structurally Damaged Pipe
Random vs. Successive
Manhole Sections
b) No provisions or allowances are made for any sewer cleaning.
(Cost of this task is portrayed in a previous portion of this
Section.)
c) No provisions or allowances are made for any pre-inspection of
the individual line sections to be grouted. (Cost of this task
covered in a previous part of this Section.)
d) No provisions or allowances are made for any soil tests, analysis,
etc., necessary to substantiate that the soil is groutable.
e) No provisions or allowances are made for any other investigative
work required to pre-establish the probability of a successful
grouting application.
To further establish some base line criteria for cost calculation
purposes, Example 5 was developed and is used in Figures 9 through 13
to indicate what the cost might be as compared to a minimum and maximum
cost based upon the number of joints grouted per setup, by diameter of
pipe.
77
-------
1600
|
11400
e
11200
"§1000
s
X 800
i
600
400
200
BASED ON:
1) 4-foot (1.2 m)
2) No bypass requirement
3) 1974 labor and material cost
INCREASED DIFFICULTY/COST FACTORS
"""
.,„...
tit«|l"liilli*COST BASED ON EXAMPLE _.
_ --- —
"""
DECREASED DIFFICULTY/COST FACTORS
10
20 30 40
Number of Joints Grouted
50
60
70
Figure 9.
2200
2000
tn
11800
11600
en
~1400
il200
.1000
I.
«
8
g- 800
M
O 600
400
200
Grouting cost per 300 ft (91 m) manhole section
pipe versus number of joints grouted.
BASED ON:
1) 4-foot (1.2 m) joint spacing
2) No bypass requirement
3) 1974 labor and material cost
- 8-12 inches (20-30 cm)
INCREASED DIFFICULTY/COST FACTORS
COST BASED ON EXAMPLE
>**»»
DECREASED DIFFICULTY/COST FACTORS
JL
10
30 40 50
Number of Joints Grouted
60
70
Figure 10. Grouting cost per 300 ft (91 m)manhole section
pipe versus number of joints grouted.
- 15-18 inches (38-45 cm)
78
-------
V
I
_d»
O
E
o
O
3000
2800
2600
2400.
2200.
2000
1800
1600
1400
1200
1000
800
600
400.
200
100-
BASED ON:
1) 4-foot (1.2 m) joint spacing
2) No bypass requirement
3) 1974 labor and material cost
INCREASED DIFFICULTY/COST FACTORS
BASED ON EXAMPLE
DECREASED DIFFICULTY/COST FACTORS
10 20 30 40 50 60
Number of Joints Grouted
70
Figure 11. Grouting cost per 300 ft (91 m) manhole section — 6 in. (15 cm) pipe
versus number of joints grouted.
79
-------
1
CO
•§
E
5
£
i
I
o
o
o>
c
4400
4200-1
4000
3800
3600
3400
3200
3000
2800
2600
2400
2200
2000
1800
1600
1400
1200
1000-
800
600-
400
200-
INCREASED DIFFICULTY/COST FACTORS
COST BASED ON EXAMPLE
x%
DECREASED DIFFICUtTY/COST FACTORS
BASED ON:
1) 4-foot (1.2 m) joint spacing
2) No bypass requirement
3) 1974 labor and material cost
10 20 30 40 50 60
Number of Joints Grouted
70
Figure 12. Grouting cost per 300 ft (91 m) manhole section — 21-24 inches (53-61 cm)
pipe versus number of joints grouted.
80
-------
•f
o
0)
V)
03
jj
(0
o
o
CO
i
o
O
4400
4200-
4000
3800
3600-
3400-
3200
3000
2800
2600
2400
2200
2000
1800
1600
1400-
1200-
1000-
800-
600-
400-
200-
INCREASEDi DIFFICULTY/COST FACTORS
3ASED ON EXAMPLE
DECREASED DIFFICULTY/COST FACTORS
BASED ON:
1) 4-foot (1.2 m) joint spacing
2) No bypass requirement
3) 1974 labor and material cost
10
20
70
30 40 50 60
Number of Joints Grouted
Figure 13. Grouting cost per 300 ft (91 m) manhole section — 30-36 inches
(76-91 cm) pipe versus number of joints grouted.
81
-------
EXAMPLE 5
Cost of Grouting
Difficulty/Cost Factor
Mobilization Distance
Weather Conditions
Access to Manholes
Traffic Control
Manhole Opening
Manhole Diameter
Manhole Condition
Manhole Depths
Pipe Size
Type of Pipe
Depth of Flow
Hazardous Gas
Type of Joint
Joint Spacing
Structurally Damaged Pipe
Random vs. Successive
Manhole Sections
Pipe Lining (Polyethylene)
Condi tion
- Project site within 100 mi
(161 km) of company office
and shop facilities
- Mild temperatures; absence
of storms
- Both manholes readily
accessible by paved road and
will accommodate the necessary
equipment
- None required
- 21 in. (53 cm)
- 4 ft (1.2 m)
- Structurally sound, with
steps for personnel access
- Between 6 ft (1.8 m) and
8 ft (2.4 m)
- Ranging from 6 in. (15 cm)
through 36 in. (91 cm) in diameter
- Vitrified clay
- Less than 20 percent of pipe
diameter
- None present
- Factory made
- 4 ft (1.2 m)
- None
- All sections requiring grouting
are successive
The costs of rehabilitating sewer lines by insertion of polyethylene
liner pipe will vary greatly due to the large number of variables and
difficulty factors which may be encountered. These factors are shown in
Tables 7 and 8.
82
-------
TABLE 7. PIPE LINING COST VARIABLES
o Liner pipe wall thickness required
o Annulus grouting requirements
o
Number of service connections to be made
o Size of pipe to be lined
o Type of surface restoration required
o Pipe transportation requirements
o Type of manhole "seals" needed
o Length of sewer to be lined
o Availability and cost of labor
o Extent of sewer cleaning required
o The technique to "prove" or pre-inspect the sewer line
TABLE 8. PIPE LINING DIFFICULTY/COST FACTORS
o Mobilization distance
o Size of liner pipe to be handled
o Depth of sewer to be lined
o Excavation requirements
o Groundwater elevation
o Grade and direction change of the sewer to be lined
o Depth of flow in the sewer line
o Lining Costs
o Access to the site of work
o Availability of electrical power for fusing
o Storage area at the site for pipe materials
o Storage area at the site for excavated materials
Each of these factors, independently or in combination, can have a
major impact on the overall cost of a lining project. A thorough under-
standing of each of these factors on an individual project basis is required
before a realistic cost estimate can be made. Table 9 is presented as an
illustration of a typical "Estimating Guide." It identifies the cost
elements by sequence of task that can be segregated for cost determination
purposes.
Each lining project is sufficiently different in its complexities,
combinations of difficulty factors, and variables to make the presentation
of any general total cost information impossible. It is the intent of this
section to provide the reader with a general understanding of the various
factors that may effect the cost of a project (Tables 7 and 8) and the
83
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elements that must be considered when developing a cost estimate,
TABLE 9. TYPICAL ESTIMATING GUIDE (COST ELEMENTS)
B.
D,
PREPARATION
1. Sewer Line Cleaning
2. TV Inspection
3. "Proving" of Sewer Line
COST OF PIPE
1. Diameter of Existing Sewer
2. Diameter of Liner Pipe
3. Depth of Sewer Line
4. Wall Thickness and Strength Required
5. Length of Pipe Required
6. Cost per Ib (kg)
7. Weight Required
8. Freight to the Site
INSERTION PITS
1. Depth of Pit
2. Equipment Required
3. Crew Size Required
4. Crew Cost
5. Time Required
6. Special Conditions
a) Shoring Required
b) De-Watering Required
7. Cement for Curing Liner Pit
8. Paving Required
9. Manhole Repairs
WELDING PIPE
1. Crew Size Required
2. Crew Rate
3. Number of Welds per Day
4. Equipment Required - Handling and Fusion
5. Power Requirements
84
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TABLE 9. (continued)
E. INSTALLING PIPE
1. Winch Equipment Required
2. Pipe Handling Equipment Required
3 . Guide" Pulleys Required
4. Cable
F. OTHER CONSIDERATIONS
1". Sewage By-Passing Requirements
2. De-Watering Requirements
3. Annulus Grouting Requirements
G. CONNECTING BUILDING SEWERS
1. Type of Connection to be Made
2. Depth of Connection
3. Crew Size Required
4. Crew Rate
5. Number of Connections Made per Day
6. Equipment Required
7. Materials Required
8. Cost of Materials
Ho SEALING OFF AT MANHOLES
1. Number of Manholes to Seal
2. Type of Seal Required
3. Cost of Seals
4. Number of Seals Made per Day
.5. Crew Size Required
6. Crew Rate
I. TRANSPORTATION
1. Mobilization
2, Demobilization
3. Freight on Materials
Specific cost examples are given and are summarized in Table 10. The
examples are intended to demonstrate the wide range of project costs and
show the influence of some of the difficulty factors.
85
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TABLE 10. EXAMPLE COST SUMMARY
Cost Element
Preparation
Cost of Pipe
Insertion Pit
Welding Pipe
Installation of Pipe
Connect 15 Building Sewers
Sealing off Manholes
Mobilization
TOTAL PROJECT COSTS
Situation A
1,000 ft (305m)
8 in. (20 cm) pipe
(concrete)
8 ft (2.4 m) deep
$ 1,000
2,000
6,000
700
2,500
4,500
1,000
300
$18,000
Situation B
1,000 ft (305m)
8 in. (20 cm) pipe
(concrete)
25ft (7.6 m) deep
$ 1,000
4,000
16,000
800
3,200
9,000
1,500
500
$36,000
Situation C
1,000ft (305m)
24 in. (61 cm) pipe
(concrete)
25 ft (7.6 m) deep
$ 2,500
35,000
20,000
3,000
6,000
10,000
1,500
2,000
$80,000
It is important to remember, as mentioned previously, that each lining
project should be cost-evaluated independently, considering all of the
specific job requirements, variables and difficulty factors. As illustrated
in the Example 6, e'ach project must be costed by the sub-elements involved
in order to account for the difficulty factors. The lining cost could vary
by over 400 percent depending upon such factors as groundwater depth,
depth of pipe, mobilization distance, and size of pipe involved.
EXAMPLE 6 Cost of Pipe Lining
Situation A
Size and Type of Pipe:
Depth of Flow:
Length of Sewer:
Depth of Seweri
Groundwater Elevation:
Soil Typer
Access to the Site:
Pre-Inspection:
Excavation Requirements:
Building Sewer Connection:
8 in. (20 cm) Concrete
20% of Pipe Diameter
1,000 ft (305 m)
8 ft (2.4 m)
3 ft (0.9 m) above Sewer Invert
Clay
Open Field, OK for Vehicles
Proved Acceptance of Liner
Single Excavation Adequate
15 Connections, Replace to
Property Line
86
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Annulus Grouting Requirements:
Manhole Seals Required:
Liner Thickness:
Mobilization Distance:
Situation B
Size and Type of Piper
Depth of Flow:
Length of Sewer:
Depth of Sewer:
Groundwater Elevation:
Soil Type:
Access to the Site:
Pre-Inspection:
Excavation Requirements:
Building Sewer Connection
Annulus Grouting Requirements:
Manhole Seals Required:
Liner Thickness*
Mobilization Distance:
Situation C
Size and Type of Pipe:
Depth of Flow:
Length of Sewer:
Depth of Sewer:
Groundwater Elevation:
Soil Type:
Access to the Site:
Pre-Inspection:
Excavation Requirements:
Building Sewer Connections:
Not Required
4 Manholes, 6 Seals
SDR^D 32.5 Wall Thickness
200 mi (322 km) from Installer
8 in. (20 cm) Concrete
20% of Pipe Diameter
1,000 ft (305 m)
25 ft (7.6 m )
17 ft (5.2 m) above Sewer Invert
0-6 Clay 6-25 Muck and Sand
Open Field, OK for Vehicles
Proved Acceptance of Liner
Single Excavation Adequate
15 Connections, Replace to
Property Line
Not Required
4 Manholes, 6 Seals
SDR 17 Wall Thickness
200 mi (322 km) from Installer
24 in. (61 m) Concrete
20% of Pipe Diameter
1,000 ft (305 m)
25 ft (706 m)
17 ft (5.2 m) above Sewer Invert
0-6 Clay 6-25 Muck and Sand
Open Field, OK for Vehicles
Proved Acceptance of Liner
Single Excavation Adequate
15 Connections, Replace to
Property Line
Not Required
(1)
Annulus Grouting Requirements:
SDR - Size Dimension Ratio, Outside Diameter divided by wall thickness.
87
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Manhole Seals Requiredr
Liner Thickness:.
Mobilization Distance:
4 Manholes, 6 Seals
SDR 17 Wall Thickness
200 mi (322 km) from Installer
REFERENCES
1.
2.
3.
4.
5.
AAA Pipe Cleaning Corporation, Technical Bulletin,
March 19, 1975.
Ahrens, J.F., Leonard, O.A., and Townley, N.R., "Chemical
Control of Tree Roots in Sewer Lines." Journal Water Pollution
Control Federation, September, 1970, page 1643.
Townley, N.R., Research Report, "Chemical Control of Roots."
Sacramento County Department of Public Works, Water Quality
Division, September, 1973.
Abstract from paper presented at February, 1972 Meeting of the
Weed Science Society of America, by J. F. Ahrens, Connecticut
Agricultural Experimental Station, Windsor, Connecticut.
Conklin, J.'T., Research Report, "Thermo-Eradix" Process.
Penetryn Systems, Inc., April, 1970.
The
88
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SECTION III
DESIGN STANDARDS AND CONSTRUCTION METHODS
FOR THE CONTROL OF INFILTRATION AND INFLOW
IN NEW SEWER SYSTEMS
In recent years there have been many improvements in pipe products,
jointing systems, sewer line construction and methods of field acceptance
testing. These developments have generated changes in existing applicable
ASTM Standards as well as the issuance of new ASTM Standards„ The
purpose of this section is to provide guidance for all parties associated
with the design and construction of sanitary sewers and to make them
aware of the alternate choices available in sewer pipe materials, jointing
systems and current, applicable national standards„
Because of the increased national attention focused on the control
of I/I into sewer systems, the subjects of allowable leakage limits,
suitable methods for field acceptance testing, air-tightness, photography
of pipe line interiors, closed-circuit TV inspection and field determi-
nation of misalignment or excessive diametric deflection will be discussed,,
In addition, recognition will be made of the fact that different
types of pipe and jointing systems require different installation pro-
cedures. Different construction conditions involving rock, muck, land-
fills, etc. may require individual and specialized construction methods
regardless of the type of pipe being installed,
Predesign Investigations
Soil and groundwater conditions; must be considered in the design
if a proposed sewer system is to avoid excessive infiltration. Seasonal
variations in groundwater elevation, percolation characteristics of soil
strata and load-bearing capacity of undisturbed geological formations all
influence potential infiltration possibilities.
Possible investigative reconnaissance procedures include:
o Geological maps.
o Aerial photographs.
o Flood records.
o Reports of previous engineering studies.
o Municipal engineer's records.
o Telephone calls to local builders, residents, utilities and
contracts with public employees.
o Site visits.
89
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Possible subsurface investigation procedures include:
o
o
o
o
o
o
Test pits0
Probing,
Auger borings.
Machine borings.
Geophysical explorations (seismic and electrical retraction)
Long-term monitoring of water level variations.
Soil tests—-in-situ and laboratory procedures include:
o
o
o
Soil classification,,
Soil performance,
Groundwater quality and characteristics.
Soils and Soil Classification; to identify a specific soil and
interpret its properties- as related to infiltration conditions, it is
necessary to have some knowledge of soil classification. Classification
tests, such as sieve and hydrometer analyses, provide information on the
physical characteristics of the soils. Test results may be useful in
deciding if a material (1) is suitable for bedding and/or backfill; (2)
will cause problems in dewatering as they pertain to pumping of fines and
subsequent soil settlement; and (3) is likely to affect the volume, rate
and quality of future flow of groundwater»
Performance tests are more specific in determining the load-bearing
or permeability potential of soils. Chemical analysis of soil and
groundwater may be important in some areas. Simple field classification
and performance tests are available to check in-situ density of both
undisturbed and recompacted soils. Commonly used field tests are the
Sand Cone Method and the Rubber Balloon Method,
Soil classification systems usually include references to color,
grain sizes, plasticity and cohesiveness, with interpretation as to
permeability and load-bearing characteristics. For example, a "Brown
course SAND, little medium GRAVEL" will indicate a cohesionless material with
high permeability and groundwater flow, and probable usefulness as a
bedding material, A "silty CLAY" could be interpreted as a poor bedding
but likely to impede water flow to or along the sewer.
Soil studies include geology and rock formations encountered in
predesign investigations. Rock types should be classified as to strati-
fication, porosity, hardness, friability, and water-bearing or trans-
porting characteristics. Water-laden rock formations can be as infil-
tration causative as water-bearing sands or gravels,
Design Allowance for I/I
Infiltration allowances are generally stated in the form of volume
per unit of time, per unit of length and per unit of pipe size. The
calculated volume is added to the peak design flows of domestic sewage
and industrial wastes to establish pipe and wastewater treatment plant
90
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unit sizes. The peak design flow is the maximum daily rate of flow
resulting from highest usage during certain hours of the day, days of ,
the week, and weeks of the year. The design flow is based on the
principle that at some specific moment, wastewater flows will be at
peak volume because of the accumulation or combination of maximum usage
conditions. This peak, however, may never actually occur. A number of
state agencies stipulate peak design flow as a specific volume or
quantity per capita. Table 11 lists design flows required by some states
and provinces.
Other jurisdictions have developed peak rate curves. Figure 14 is
the rate chart used by Washington, B.C.
Peak design flows must be carefully ascertained. Some design
standards and designer practices, as illustrated by Table 11, lump all
extraneous flows into some vague multiplier for an assumed average daily
flow. Assumed I/I can vary greatly from jurisdiction to jurisdiction,
e.g., from a low of 10 percent of normal sanitary flow to 100 to 200
percent based on an APWA study (1). Each designer should evaluate the con-
ditions existing in the sewer system involved and not simply use a con-
venient and unsubstantiated design allowance. If arbitrary allowances
are made without careful examination of local conditions and the esta-
blishment of realistic design criteria, the system may be seriously
over-designed or under-designed.
As previously discussed, a goal in sewer system and wastewater
management is to minimize the entry of I/I and, thereby, keep associated
sewer system treatment costs at a minimum and eliminate maintenance and
operating costs arising from soil fines entering the system under infil-
tration situations. There always will be at least a small increment of
infiltration which it is not cost-effective to eliminate. The expense
of the pipe, and increases in construction and inspection costs fix the
lower limit for infiltration allowance. Inflow must also be carefully
considered. Considerable variations in the amount of inflow may be
experienced, depending on the effectiveness and permissiveness of local
control with respect to sewer-use ordinances and their enforcement.
In the past some sewer designers have used such infiltration flow
units as gallons or cubic, feet per acre per day. This terminology is a
holdover from the past, based on the old concept of storm and combined
sewer design. Since an attempt now is being made to eliminate or minimize
all excess water intrusions, allowances should be keyed to actual flow
records or estimates from sources of flow such as per capita or per
dwelling unit. Sometimes I/I rates are assumed as a percentage of the
per capita flow as indicated by water use and recognized standards. Such
determinations may be adequate for overall systems planning but are not
sufficiently definitive for detailed final design.
An accurate estimate of I/I allowances should be divided into two
basic components:
A. Infiltration Component
Since infiltration is related to tightness of pipe, manholes
91
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TABLE 11
DESIGN FLOWS FOR SEWERS AND TREATMENT FACILITIES
A. DESIGNATED BY STATE REGULATIONS
Alberta
1) Maximum hourly flow = average daily x
14
4 + p
0.5
when P = population in thousands, range of maximum
hourly flow is from 2 to 4 times average daily
2) Per capita average daily flow = 100 gal (378.5 1)
Illinois
1) Laterals and submains - 400 gal (1514 1) per capita per day.
2) Main, trunk and outfall sewers - 250 gal (946.3 1) per capita per day.
3) Per capita average daily flow = 100 gal (378.5 1).
New Jersey
1) Sewers designed to carry at least twice the estimated average
design flow when flowing half full.
2) Per capita average daily flow = 100 gal (378.5 1).
New Hampshire
1) All sanitary sewers shall be designed to carry at least four times
the estimated average design flow when full.
2) Interceptors shall be designed to carry at least two and one-half
the average design flow when full.
3) Per capita average daily flow = 100 gal (378.5 1).
Oklahoma
1) Laterals and submain sewers designed for 400 gal (1514 1) per capita
per day when running full.
2) Main, trunk, interceptor and outfall sewers shall have capacity
of at least 250 gal (946.3 l)per capita per day when running full.
3) Per capita average daily flow = 100 gal (378.5 1).
4) The 100 gal (378.5 1) per-capita-per-day figure was assumed to cover
normal infiltration, but an additional allowance should be made
where conditions are especially unfavorable. This figure likewise
is considered sufficient to cover flow from cellar floor drains,
but is not sufficient to provide any allowance for flow from
foundation drains, roof leaders, or unpolluted cooling water,
which should not be discharged to sanitary sewer systems.
92
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TABLE 11 (Continued)
Oregon
1) Because usually it is impossible to exclude all groundwater
infiltration, it is recommended that the capacity of sanitary
sewers when flowing full be equivalent to at least 300 gal (1135.5 1)
per capita per day and preferably 350 gal (1324.8 1) tier capita oer
day on the basis of total estimated future population. Trunk and
interceptor sewers should in general have capacities equal to at
least 250 gal (946.3 1) per capita per dav.
Pennsylvania
1) Laterals and submain sewers - 400 gal (1514 1) per capita per day.
Main, trunk and outfall sewers - 250 gal (946.3 1) per capita per day.
2) Per capita average daily flow = 100 gal (378.5 1).
Tennessee
1) Laterals and submain sewers - 400 gal (1514 1) per capita per day.
Main, trunk and outfall sewers - 250 gal (946.3 1) per capita per day.
2)
Texas
1)
Per capita average daily flow = 100 gal (378.5 1).
Laterals and minor sewers shall be designed, when flowing full,
assuming flows equivalent to four times average daily flow. Main
trunk interceptor, and outfall sewers shall be designed when
flowing full, assuming flows of 2.5 times the average daily flow.
2) Per capita average daily flow = 100 gal (378.5 1).
Utah
1) Laterals and submain sewers - 400 gal (1514 1) per capita per day
Main, trunk and outfall sewers - 250 gal (946.3 1) per capita per day.
2) Per capi'ta average daily flow = 100 gal (378.5 1).
Source: "Prevention & Correction of Excessive Infiltration & Inflow
into Sewer Systems--A Manual of Practice", #11022EFF 01/71
Prepared for USEPA by APWA0
93
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TABLE 11 (Continued)
B. LOCAL AUTHORITY POLICIES AND ACTIONS
Local Authority
Hartford, CT.
New York, NY.
Philadelphia, PA.
Hampton Rds., S.D., VA.
Miami -Bade Co. W&B Auth.
Louis. J.H. Co. KY.
Louis. -Dav. Co. TN.
MSD Chicago, IL.
Detroit Metro, MI.
Wayne Co . , MI .
MED Cinn. OH.
Dayton, OH.
MSB, St Paul, MN.
MSB, Milwaukee, WI.
New Orleans, LA.
Dallas, TX.
Ft. Worth, TX.
Witchita, KS0
Kansas City, MO.
St. Louis, MO.
MSD, Denver, CO.
Orange Co., CA.
Sacramento, CA.
Metro, Seattle, WA.
Allowable
Infiltra-
tion
Gal/In.-Dia/
Mi /Day
200
250-500
2,000
500
200
300
200
500
250
200
150
500
100
200
200
200
150
180
200
200
200
,190
500
600
(Metric)
I/ Cm-Dia/
Km/Day
, 185.2
231.5-463
1852
463
185.2
277.8
185.2
463
231.5
185.2
138.9
463
92.6
185.2
185 .,2
185.2
138.9
166.7
185.2
185.2
185.2
175.9
463
555.6
Source^ "An Analysis of the Environmental Protection Agency Needs Survey,"
April, 1975, prepared for National Commission on Water Quality
by APWA.
94
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I
c
Q
8,4
I
2 3
I
Use this curve for average flow up to
[26.5 (103) m3/day]
Continued below
J_
2345
Yearly Average Sewage Flow, Exclusive of Stormwater Runoff, in mgd.
See above for ratio within this range
NOTE:
Data on this sheet apply to dry-weather flow,
with no allowance for Stormwater runoff.
Ratio of 2.0 to be used for yearly average
flows exceeding [227 (103) m3/day] 60 mgd.
5 I
4 I
re
a
3 1
OJ
CO
w
0)
2 1
03
o.
5 -£
s
o
«^
o
o
3 1
tr
10 20 30 40
Yearly Average Sewage Flow, Exclusive of Stormwater Runoff in mgd. (3,785 m3/day)
Figure 14. Ratio of peak sewage flow to average flow.
Source: District of Columbia Department of Sanitary Engineering
95
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and other structures such as pump stations, any design allowance
should be correlated with the maximum allowable construction
infiltration allowances, While the full discussion of con-
struction allowances is contained later in this section, it is
sufficient to note that any amounts of permitted infiltratioa
must be considered in the design. In effect then, the design
infiltration component should be a function of the infiltration
allowance used in this relationship and should be the maximum
allowable system average, rather than the maximum allowable
between manholes,
Be Inflow Component
Where a new sewer system is being designed in a jurisdiction
that forbids the interconnection of any drainage, storm, or
clean waters and where enforcement is complete and effective,
there would be no inflow component. Such a system is difficult
to achieve; to accomplish it the following inflow sources would
have to be prohibited and enforced:
o Roof downspouts„
o Foundation drains,
o Basement drains.
o Basement sumps and/or capped clean-outs,
o Sump pumps,
o Areaway drains,
o Driveway drains,
o Yard drains.
o Street drains,
o Perforated or poorly sealed manhole covers in areas
of potential flooding.
Since initial achievement and continued realization of such
restrictions are never completely realized, the acceptable inflow
component must be an engineering judgement factor tailored to fit the
individual local situation. In terms of an average per capita sanitary
contribution of 100 gal (378.5 1) per day, an inflow component of 5 gal
(19 1) per capita per day might be chosen or some amount determined from
previous I/I studies for comparable areas.
When local regulations permit connections of "clean water" to the
separate sanitary system and they cannot be tightened by any amount of
logic and persuasion used to convince local officials, the design
engineer should develop inflow or stormwater allowance curves for the
system. These curves result from studies of permitted inflow in terms
of paved areas per dwelling unit or per person and in consideration of
a certain maximum storm toleration. Figure 15 was developed by the
District of Columbia, Sanitary Engineering Department, which has
selected a 15-year storm as the design storm. Figure 16 shows the storm-
water allowance curves for a design storm falling on various acreage
areas with varying population densities. These represent an attempt to
correlate lot or plot area with population, A straight-forward use of
96
-------
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(0
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~~ S
Q
u
C
E
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T3
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d
w
•H
§
C/3
o
4-1
c
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4J
CO
•H
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rH
O
U
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•H
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97
-------
§
•p6iu ui aouewoiiv
98
-------
infiltration or inflow criteria on strictly an area basis becomes meaning-
less when population development or potential development is ignored.
The District of Columbia charts are useful as an illustration of
the concept of inflow component allowances. However, they also incor-
porate a flat 700 gal/ac (6,625 1/ha) per day figure representing
yearly average flow of groundwater infiltration. Such an assumption
does not take into account varying lengths of pipe, population densi-
ties, and types of buildings. Four hundred people/ac (1,000/ha) in
high rise apartments would produce considerable less infiltration
potential than 285 people in 70 single-family homes on 0.5 ac (0.2 ha)
lots. However, in a combined system such as in the District of
Columbia, which also permits outside areaway drains, the infiltration
load is of less significance.
Example 7 illustrates the use of design I/I allowances and the
varying impact on resultant flows. These may or may not apply to con-
ditions existent in other jurisdictions. A basic design assumption is
that infiltration and inflow represent additional volume, over and
above the peak domestic flow of four times the average daily flow.
EXAMPLE 7
ILLUSTRATION OF DESIGN I/I
ALLOWANCE CALCULATIONS
Assumed Conditions: Tight system with no permitted inflow
Area 1,200 ac (486 ha)
Population Density - 20 persons/ac (0.2 ha)
Total Population -24,000
Separate Sanitary System
4 in.
8 in.
10 in.
12 in.
(10.2 cm)
(20.3 cm)
(25.4 cm)
(30.5 cm)
building sewers
street laterals
sub-trunks
trunk
36 mi (57.9 km)
24 mi (38.7 km)
6 mi (9.7 km)
6 mi ( 9.7 km)
Average Daily Per Capita Sanitary Contribution - 80 gal (302.8 1)
Peak Design Flow - 3 times average daily flow
Additional Assumptions::
Design Infiltration Component = 200 gal/in.-diam/mi/day
(185.2 1/cm-diam/km/day).
Maximum Inflow = 5 gal/person/day (19 1 /person/day)
Maximum Infiltration Component
800 gal/mi/day x 36 mi = 28,800 gal/day (109,008 I/day)
1600 gal/mi/day x 24 mi = 38.400 gal/day (145,344 I/day)
2000 gal/mi/day x 6 mi = 12,000 gal/day ( 45,420 I/day)
2400 gal/mi/day x 6 mi = 14,400 gal/day ( 54,504 I/day)
Total 93,600 gal/day (354,276 I/day)
99
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EXAMPLE 7 (Continued)
Maximum Inflow Component
5 gal/person/day (19 I/person/day) x 24,000
= 120,000 gal/day (454,??0 I/day)
Total Maximum I/I Component = 213,600 gal/day (808,476 I/day).
Peak Design Flow
80 gal/person/day (302.8 I/person/day) x 24,000 x 3
= 5,760,000 gal/day (21,801,600 I/day),
Total Peak Design Flow
=5,973,600 gal/day (22,610,076 I/day)
• ' °r „ ,
* (22,610 nrYday)
Additional Assumed Conditions for System Slightly Less Tight and
Some Areaway Drains Permitted
Design Infiltration Component = 500 gal/in.-diam/mi/day (463 I/
cm-diam/km/day)
Inflow Calculated from Washington, D0C,, Stormwater Allowance Curve
(Figure 16)
Maximum Infiltration Component:
2,000 gal/mi/day x 36 mi = 72,000 gal/day (: 2,520 I/day)
4,000 gal/mi/day x 24 mi = 96,000 gal/day (3 3,360 I/day)
5,000 gal/mi/day x 6 mi = 30,000 gal/day (113,550 I/day)
6,000 gal/mi/day x 6 mi = 36,000 gal/day (136,260 I/day)
Maximum Total Infiltration Component = 234,000 gal/day
(885,690 I/day)
Inflow Component from Figure 16 = 6,000,000 gal/day
(22,710,000 I/day)
Total Infiltration/Inflow = 6,234,000 gal/day
(23,595,690 I/day)
Peak Design Flow = 80 gal/person/day (302.8 I/person/day)
x 24,000 x 3 = 5,760,000 gal/day
(21,801,600 I/day)
Total Peak Domestic Design Flow = 11,994,000 gal/day
(45,397,290 I/day)
or
(45,397 m3/day).
100
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The example not only illustrates the methods for arriving at peak
design flows; it also shows how, in the same theoretical design area,
seemingly small variations in design criteria can result in great dif-
ferences in flows and pipe sizes.
The increase in the design infiltration component from 200 to 500
gal/mi/in-dia/day (185.2 to 463 1/km/em-dia/day) raises the total
infiltration from 2 to 5 percent of the sanitary flowe In terms of
actual volumes, the 500 ga.l/mi/in.-dia/day (463 1/km/cm-dia/day) allow-
ance, which is in use at the time, would permit entry of a maximum of
85.6 mg (324,000 m^ ) of extraneous water per year.
The most striking change in extraneous water flew occurs in the
inflow component of the additional assumed conditions, utilizing the
Washington, D.C. design curves for stormwater (inflow) into separate
sanitary sewers. In this case the inflow alone is 6 mgd(22,710 m^/day)
which almost equals the peak sanitary design flow and dwarfs the infil-
tration component even in its increased condition.
This Illustrative example is over-simplified in order to emphasize
the impact of differing design and construction allowances„ In actual
practice pipe sizes would he varied according to the design flows in a
slightly more involved procedure„
Gravity Sewer Pipe and Jointing Materials
Types of Sewer Pipe
Improvements and developments in pipe materials ensure that the
designer can provide proper materials to meet rigid infiltration allow-
ances . The basic question of water-tightness of pipe material should
be of as much concern as problems of structural integrity and chemical
characteristics of the wastewater to be handled. In addition, local
soil, gradient, or special installation conditions could make one pipe
material more appropriate than another in specific instances.
The design of sewer lines which will be operated under pressure
must be carefully evaluated. The pressures to be used may have a direct
impact on the decision as to the type of pipe which must be used. How-
ever, pressure-type sewer, systems are beyond the scope of this manual;
the data herein relate to gravity sewer systems.
Appendix F was adapted from information published by the American
Society for Testing and Materials (ASTM) from their Standards for Selected
Sewer Pipe and Appurtenances.
Sewer Jointing to Control Infiltration
The effectiveness of sewer joints for the control of infiltration
is so important that no sewer system is better than its joints. A good
joint must be water-tight, root penetration-tight, resistant to the
effects of soil and wastewater, and long-lasting.
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It should be recognized by the engineer, however, that field
performance represents the sum of the manufactured joint characteristics
and the contractor's installation practices,, None of the currently
produced jointing systems for the various types of sewer pipe is abso-
lutely fool-proofo However, each has inherent capabilities which, when
combined with appropriate installation procedures, will provide excellent
field performancee
The following methods of jointing are used in sewer service with the
listed types of pipe:
Asbestos-Cement Pipe—Asbestos-cement sewer pipe joints consist of
a sleeve coupling and two rubber gaskets„ The gaskets, which are
positioned in grooves situated in the coupling sleeves, are compressed
between the finished pipe ends and the coupling grooves„ Joint design
and assembly provide separation of the pipe ends to provide joint
flexibility. Figure 17 shows a typical joint.
Courtesy: Certain-teed Products Corporation
Figure 17. Typical asbestos cement sewer pipe joint.
Clay Pipe--Several jointing systems are in common usage in various
areas of the country and examples are shown in Figure 18.
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Source: United States Concrete Pipe Company
•a. No Bell
Source: Logan Clay Pipe Company
b. Bell
Figure 18. Clay pipe sewer joints.
For bell and spigot pipe, most manufacturers supply a factory-
applied compression joint in which a filled plastic thermosetting resin-
is applied to produce concentric surfaces in the bell and on the spigot.
In some designs an elastomeric resin, such as urethane or plasticized
PVC is molded into an annular bead or fin pattern on one or both castings
to act as the sealing device. Where the resin is rigid, a separate 0-
ring rubber gasket, positioned in a groove in the spigot resin, is the
compression sealing unit.
Plain-end clay pipe, i.e., without clay bell, is now being supplied
by many manufacturers with, a factory-applied joint.
Such joints include:
1 10 A rigid socket PVC or glass-reinforced thermosetting resin
attached to one end and a sealing device of urethane
elastomer or conventional 0-ring rubber gasket system on
the other.
2. A urethane elastomer on both ends with a rigid PVC or
glass-reinforced thermoplastic external coupling sleeve.
Sealing beads may be in the sleeve or on the spigot.
3. True plain end pipe may be coupled with an external
sleeve of rubber or elastomeric plastic, tightened
in place with stainless steel circumferential bands.
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This third type is offered for both new construction and repairs,
or adjustments to field laying length conditions.
Concrete Pipe—Each concrete pipe is provided with a male joint
(spigot or tongue) and a female joint (bell or groove) formed inte-
grally with the pipe wall.
Circular concrete pipe for sanitary sewers is provided with internal,
compression-type joints, in which the natural and/or synthetic rubber
gaskets are compressed in the annular space between the mating surfaces
to form a watertight seal when installed. Joint geometry and gasket
cross-sectional shapes vary, but in every type the gasket is the sole
sealing element depended upon to make the joint flexible and watertight.
Non-circular concrete pipe is not compatible with the use of inter-
ior rubber gasket joints. Satisfactory results have been obtained with
these shapes by the use of external elastomeric bands or carefully
applied mastic fillers for the joints. A relatively successful innovation
in this latter type involves the use of preformed mastic segments which
facilitate handling and provide uniform applications.
Plastic Pipe—Low profile sockets for plastic pipe may be either
extruded and belled slightly to receive the spigot or cemented to the
pipe subsequent to extrusion.
Acrylonitrile-Butadiene-Styrene (ABS) pipe is jointed by a sleeve
socket solvent cemented to one end by the manufacturer and sealed by
either a solvent cement method or rubber gasket. In the solvent cement
method, the spigot is wedged and rotated into the tapered socket and the
two surfaces are fused together by the solvent. In the gasket method,
the coupling is double-belled to provide proper positioning for the
gasket and a gasket stop is cemented on the spigot to retain the gasket
in compression. A typical joint is shown in Figure 19.
Polyvinyl chloride (PVC) pipe may be jointed either by a solvent
cement system or rubber gaskets. In the solvent cement joint, the pipe
spigot is wedged into the tapered socket and the two surfaces fused
together by the socket. Rubber gasketed joints utilize rubber rings
placed inside the bell.
Steel Pipe—Corrugated metal pipe as used for sanitary sewers has
joints which are sealed either by flat rubber gaskets spanning the joint
and tightened against the two adjacent pipes by exterior coupling bands
or with a proprietary joint incorporating two "0" Rings seated in the pipe
end corrugations. Pipe is available in diameters of 142 in (3.6 m) or
more. Figure 20 shows a typical joint.
Jointing under in-the-wet and difficult-to-see conditions does not
lend itself to precise and careful workmanship. Regardless of the type
of pipe and jointing system used, it is important that engineering
inspectors caution contractors to clean the jointing elements immediately
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Courtesy: Armco Steel Corporation
Figure 19. A B S pipe joint.
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Source: National Corrugated Steel Pipe Association
Snug-fitting sleeve joint holds corrugated steel pipe
together and resists shearing forces of soil settlement.
No bolting is necessary.
Figure 20. Steel pipe sewer joint.
Use of 'hugger-type" connection on large storm sewer
job. Special wrench draws band tight.
prior to use. When using compression seals, such as 0-ring gaskets, the
mating units should be adequately lubricated, unless the gasket is
intended to be rolled into position, in which case it and the mating
surfaces should not be lubricated,, In the case of solvent-welded joints,
the mating surfaces should be thoroughly coated with the proper solvent
and immediately joined,, Subsequent field performance tests with air or
water should demonstrate the efficacy of the pipe and joints0
Effect of Subsurface and Groundwater Conditions
Groundwater conditions may vary seasonally or the subsurface may be
constantly dry or wet,, Where possible the existing groundwater level
should be lowered by dewatering procedures during construction in order
that a firm foundation be attained. However, the engineer must be aware
of the fact that once the dewatering procedures are terminated the
natural groundwater level will be reattained and its presence may intro-
duce the possibility of groundwater infiltration into the completed sewer,
In addition, the designer must consider the possibility that "soft'r
foundations may lead to eventual differential settlement and the possible
opening of the sewer pipe joints. The existence of differential settle-
ment may dictate the need for flexibility at the joints in order to
accommodate some pipe deflection. Whenever possible, the foundation
should be improved to minimize future maintenance problems. Most of the
types of pipe listed in this Manual of Practice are available with some
type of flexible joint.
In order to assure the long term structural and functional integrity
of new sewer construction, one of the most basic considerations should
be the control or minimization of settlement by providing an adequate
foundation for the pipe. The potential for settlement, including dif-
ferential settlement, can vary widely under different naturally occurring
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soil conditions. Extensive, soil investigations, testing and expert
geological evaluation may be required in some cases to determine the
appropriate control techniques to be applied. Where minor settlements
within an acceptable order of magnitude are anticipated, proper selection
of pipe strength and flexibility at the joint to permit a limited amount
of movement without structural hazard or loss of seal should be emphasized.
Selection of the joint may also be based on its shear transmitting
capability since differential settlement can cause stress to be trans-
mitted through the joint.
A chemical analysis of groundwater may sometimes be useful where the
sewer will be installed below groundwater or in trench conditions where
the trench backfill material may act as an aquifer. In some cases the
proper selection of pipe materials will depend on adequate soil and
groundwater tests.
Manhole and Cover Design
It is known that an important part of the total I/I into existing
sewer systems enters at manholes and specifically at connections of pipe
to manholes. Significant progress has been made to reduce leakage from
these sources, but special consideration in design and construction
remains impor tan t.
Brick and block manhole construction methods are less used today
because of the reduced availability of skilled masons in the sewer
construction field and the rising labor costs for such methods. Precast
concrete manholes have gained wide acceptance because of the convenience
of installation as shown in Figure 21. Precast manholes properly joined
with rubber gaskets or sealing compounds have been found to be watertight.
Early versions of precast structures incorporated cast-in-place bases on
which the riser elements were installed. The next stage added a precast
base in which holes were provided to accommodate the incoming and existing
pipe lines. In the field these openings were mortared closed to provide a
watertight seal. However, connections between manholes and pipe became
rigid as the concrete cured and some structural failure ensued when differen-
tial settlement occurred between the pipe and manholes. Subsequently, short
stubs of pipe were provided to allow the flexibility in the pipe joints
to accommodate differential settlement. More recently, a number of
flexible manhole connections have been devised and are in common use.
Manhole cover design is attracting more serious attention in view
of evidence that even small casting perforations can produce sizeable
contributions of extraneous inflow. It has been estimated that a single
1 in (2.54 cm) diameter hole in a manhole top covered with 6 in.(15.2 cm)
of water may produce an inflow of 11,545 gal (43.7 m3) per day5 this
exceeds the, infiltration or the inflow components in Example 7. Appendix
A is a report of laboratory testings of the flow through a manhole cover
compared to the head on the cover.
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RING AND COVER
MIN. OF
2 BRICKS
2 ft (61 cm)
4ft (1.2 m)
Figure 21. Precast concrete manhole.
Obviously, manholes located in areas subject to flooding should have
solid, sealed covers. Such covers, however, often prevent adequate
ventilation of the manhole and sewer, posing danger to maintenance
employees. Thus, the design of sections requiring sealed covers should
be given special carea Maintenance employees should check all manholes
for hazardous gases prior to entering,, It should be pointed out that
most manhole covers are not subject to inundation and extraneous inflows
and, therefore, perforations for adequate ventilation should be provided
in most cases.
^Practical and Maintainable Design
Recent investigations into sewer design problems have revealed a
serious lack of understanding and communications between design engineers
and maintenance personnel,, There are many sewer problems caused not
only by inadequate hydraulic design but also by impossible physical
structures with extended lengths of pipe, omitted manholes, curved lines
on difficult radii, and inaccessible chambers. Such design deficiencies
result in inadequate maintenance and unauthorized overflows, and usually
prevent rapid and adequate I/I surveys.
A sewer system cannot be buried and forgotten. Every effort must
be made to guarantee its maximum useable and economic life.
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Construction Methods and Inspection
Leakage in sewer systems is directly related to pipe product char-
acteristics, soil and groundwater conditions, and to the manner in which
installation is accomplished. All the sewer pipe listed previously, when
installed properly, will remain reasonably leak-free for the design life
of the system. Total costs will vary, depending on the relative care
employed by the inspector and contractor during installation, as well as
the competence of the designer in specifying material and installation
details and acceptance criteria.
Pipe Characteristics
Pipe characteristics have a definite bearing on how installation
should be carried out. In general, pipe types fall into two broad
structural categories: rigid pipe and flexible pipe. Some types of
pipe have both rigid and flexible characteristics. Pipe in each category
reacts differently under various soil conditions.
. Rigid pipe is designed and manufactured to provide sufficient ring
strength to resist anticipated field loads. Flexible pipe must, however,
obtain adequate support from the side fills to resist over-deflection.
Construction Contract Documents Related to Soils and Groundwater
Soils and groundwater information used in the design must be made
available to the construction contractor. These data are required to
evaluate the need for, or the design of, sheeting, dewatering, borrow
material, and a number of other considerations which influence construc-
tion cost estimates. Since the nature of soils and location of ground-
water levels to be encountered is of prime importance for sewer work,
all subsurface information obtained should form a part of the contract
documents. Each subsurface exploration should be clearly located on an
overall site plan since the data obtained from the exploration are
directly applicable to that particular area. Care should be taken to
avoid possible misinterpretation or misrepresentation. For example,
groundwater table elevation should be accompanied with the date of such
observation; soil and rock profiles developed from subsurface explorations
should reflect extrapolation between investigation locations and predict
the conditions most likely to prevail. The widely used exculpatory notes
which in effect say to the contractor: "We are not responsible for any
information supplied," may not be acceptable in a court of law and may
result in higher bid prices due to the contractor's uncertainty as to
what underground conditions he will encounter.
Designers and field construction personnel should be alert to the
current regulations and requirements of the Occupational Safety and
Health Administration (OSHA).
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Trenching and Excavation Methods
Trench excavation is done by hand or by machine, depending on the
location and magnitude of excavation required„ For most trenching work,
excavation by machine is more economical and efficient. Machines parti-
cularly adapted to sewer trench excavation include continuous bucket
excavators, overhead cableway or track excavators, power shovels or
backhoes and boom and bucket excavators.
Within the framework of OSHA regulations, trenches should be as
narrow as possible but wide enough to permit proper laying of pipe,
inspection of joints, and consolidation of backfill. Depending on the
type of soil, space available, groundwater level, length of time the
excavation is to remain open, and depth of excavation, the slopes are
constructed as steeply as they will stand without caving. In some areas
a minimum slope of 1:1 is specified or shoring in a vertical trench is
required. For deep excavations, particularly below the groundwater table,
the excavation must be braced or sheeted to ensure safe working conditions,
Construction should be accomplished in dry conditions; thus, if
water is encountered in the excavation, dewatering should be done by sump
pumping, use of well-point systems, or deep wells, etc.
Foundations
The foundation is that zone below the bedding which normally
immediately supports the pipe and joints. The foundation should be made
sufficiently firm by over-excavation and placement of foundation material
where needed to provide a working surface capable of supporting foot
traffic with no more than minor tracking. Hard material should be exca-
vated so as to provide a reasonably uniform, layer of bedding material of
a specified thickness. At points of transition from hard to soft native
material, both should be over-excavated as required by the engineer,
tapered out over a suitable distance, and replaced with compacted foun-
dation material. The purpose of these provisions is to assure reasonably
uniform supporting strength along the trench, so as to avoid concentrated
loading or differential settlement,
Bedding
Bedding is that zone above the foundation which supports the pipe.
Bedding material may be original ground, sand, gravel, crushed stone,
oyster shells, slag, concrete or other suitable materials that meet job
requirements. Locally available materials account for the wide range
of suitable bedding materials« Non-uniform bedding can result in pipe
settlement and creation of infiltration conditions.
In some instances material with high void ratios (such as trap
rock or clam shells) produce a watercourse around the pipe,, It is
extremely important that pipe installation and inspection be carefully
performed to preclude heavy infiltration from this type of aquifer.
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Specific information on recommended bedding of various types of
pipe are available from individual pipe companies or associations, ASCE
Manual of "Practice No. 37—WPCF Manual Practice No. 9, ASTM recommended
installation practices, and other references contain installation instruc-
tions which, when applied, will help produce tight sewers„
Backfill
Backfill is that zone above the bedded pipe, and extending to the
ground surface. Backfill is further divided into two sub-zones: the
zone around and over a pipe to a specified depth of cover; and that zone
encompassing the remainder of the backfill operation. Backfill in the
pipe zone should be made with selected materials. The remainder of the
backfill is generally governed by the type of material initially excavated*
Frozen earth, rubbish, old timber, and similar materials should be
avoided where permanent finished surfaces are desired because such
materials decompose or soften and can cause eventual surface settlement.
Depending primarily on. the location of the sewer and the anticipated
development of the area, specifications may require a specific gradation
of backfill material, as well as definite compaction requirements. In
this case, the proposed fill must be laboratory-tested to determine its
gradation and compactive characteristics.
Compaction Techniques
Regardless of location and pipe material used, the most critical
area with respect to compaction is directly around the sewer pipe. The
backfill should be placed and packed by hand under, and around the pipe
and compacted by light hand tampers. Compaction of sidefill may not
always be needed for rigid wall pipe, but is essential for flexible pipe
susceptible to deflection. As backfilling is continued to original
surface level, compaction can be achieved by machines. The entire trench
width must be compacted. Depending on the size of the excavation to be
filled, compacting equipment will range from hand-operated compacters
to large rollers.
Operational Problems
A number of commonly experienced problems deal with pipe and
equipment handling. Rough pulling of trench sheeting or advancing trench
boxes or shields without holding already installed pipe in position
can cause joints to open and result in eventual leaks.
Flowing or high water in an open trench during pipe jointing tends
to cause leaks. Water in solvent welding and soil particles in the pipe
bell or on the spigot in either rigid or flexible joints tend to impair
the integrity of the finished joints. Failure to comply with the engi-
neer's or manufacturer's jointing instructions is probably the most
common cause for failure found in iafiltration/exfiltration tests. Often
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this can be traced to inadequate preconstruction conferences or failure
to impart instructions for pipe laying operations„ This not only applies
to jointing pipe but also to making house service connections,
Inspection of Construction
Inadequate inspection and lack of technically consistent field
supervision are a far greater cause of ineffective sewer installation
than generally recognized. All too often lack of good inspection results
in failure to comply with engineering specifications. When experienced
and conscientious supervision is provided, the incidence of leakage test
failures is significantly low and long-term system performance is greatly
improved. This aspect cannot be overemphasized, particularly in this
inflationary age where the tendency is to economize to meet budgetary
limits. Nothing could be more "penny-wise but dollar foolish" than to
skimp on inspection control of sewer system construction.
Dewatering Techniques
Excavations can be dewatered by sump pumping, a well-point system,
deep wells, or soil solidification. Pumping from sump pits is most
widely used for shallow excavations when the quantity of water is small
and the water table need not be lowered any great distance. Well-point
systems and deep wells are more complex and should be designed by an
engineer. In any well-pointing procedure, caution should be exercised
in making certain that the groundwater table will be restored after
construction at approximately the same rate or in a comparable period
of time that it took to draw down the water level. This procedure will
prevent any sudden "surge" of water which could conceivably exert enough
force to cause disruption.of newly constructed sewer lines or manholes„
Some areas, notably in gulf or ocean coastal areas, have an under-
lying groundwater and type of soil or porous rock which cannot be
dewatered. In some cases it has been found possible for a contractor
to install pipe by using divers. In such cases, pipe is brought to line
and grade by the use of sand bags placed at the joint end and alignment
is achieved by control of laser beams or string line. In such cases, the
line is checked for water-tightness after completion of a section of
sewer between manholes where it is possible to dewater the system and
check for infiltration. This is not generally recommended practice,
but it is a practice that is carried out in certain areas of the
United States.
Construction Inspection and Testing of Soils, Bedding and Backfill
Infiltration of groundwater into a proposed sewer system can be
minimized by proper construction procedures, rigid inspection of mater-
ials and methods of installation, and performance of soil and ground-
water tests and the resulting correction of problems determined including:
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0 Field Inspection of Excavation, Bedding and Backfill; con-
struction procedures and materials should be inspected for
conformance with project plans and specifications. Rigid
inspection is mandatory.
° Field Soil Tests; field soil testing is used in conjunction
with controlled backfill. When specifications require back-
fill to be compacted to a high percentage of maximum density,
in-situ field density tests must be performed to determine if
such compaction is achieved. The most common means of field
density testing are the Sand Cone Method and Rubber Ballon
Method (2),both yielding a field density to be compared with
laboratory maximum density in order to monitor degree of
compaction.
o Laboratory Testing: for projects specifying a specific
gradation requirement for trench backfill or bedding, the
proposed material should be subjected to sieve and/or hydro-
meter analyses. Further, a compaction test should be per-
formed if specifications call for a required degree of
compaction.
0 On Site Testing; modern soil density devices have been proven
effective and expeditious for field applications.
Construction Leakage Allowances
The most effective way to control infiltration, and at the same
time to assure the structural quality and condition of the new instal-
lation, is to establish and enforce a maximum leakage limit as a con-
dition of job acceptance. Leakage allowances may be stated in terms
of water infiltration or exfiltration, or exfiltration of low-pressure
air. They should be stated in terms of both maximum allowable rate
per test section and maximum allowable average rate for the total pro-
ject- Manholes should be included in the allowances, or separate man-
hole test allowances should be specified.~~~~
Infiltration--
Since optimum minimization of infiltration is the desired objective
direct measurement of infiltration would appear to be the preferred
procedure. Measurements must be made, however, before any service con-
nections are functioning, and also at a time when groundwater is over
the entire test section of pipe and at or near its maximum level. This
combination of circumstances is rare and therefore infiltration testing
is practical only in a limited number of cases.
There are many opinions, but not much hard data upon which to base
infiltration requirements that are generally cost-effective. Current
information indicates that about 200 gal/mi/in-dia/day (185.2 I/km/
cm-dia/day) can normally be achieved in manhole to manhole tests with
minimum to no effect on construction cost.
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The magnitude of 200 gal/mi /in-dia/day (185.2 1/km/cm-dia/day)
when testing a normal manhole to manhole length of 300 ft (91.4 m) should
be kept in mind. The flow to be measured at this allowable infiltra-
tion rate for a 6 in. (15.2 cm) pipe will be 0.05 gal/min (0.19 1/min) .
Thus standard weirs will not generally be effective in measuring the
flow.
A 200 gal/mi/in-dia/day (185.2 1/km/cm-dia/day) infiltration
specification is appropriate for manhole to manhole testing, includ-
ing manhole sections where the groundwater is at least 2 ft (61 cm)
over the crown of the pipe, but not over 6 ft (1.8 m) in highly per-
meable soil. Tighter specifications may tend to increase the cost of
construction in excess of the operating savings achieved.
Infiltration allowance for the pipe should reflect a considera-
tion of the permeability pf the soil, particularly the envelope around
the pipe, in addition to the depth of groundwater over the pipe. This
is true because relatively fine grained soils such as clays and silts
have a tendency to partially relieve the effective external head act-
ing on the pipe and, at the same time, soil particles tend to partially
obstruct small defects in the pipe or joints, thus restricting the flow
which would occur if only clean water were involved. Highly permeable
soils, e.g., those containing large percentages of sand or gravel, do
not produce these effects, and permit the full hydrostatic head to act
directly on the pipe with no flow restrictions at potential defects.
For this reason, when the native soil and envelope around the pipe is
highly permeable, an increase in the infiltration allowance should be
provided for, if the average groundwater head exceeds 6 ft (1.8 m) . In
these instances, it is recommended that the allowable infiltration be
increased in proportion to the ratio of the square root of the actual
groundwater head to the square root of the assumed base head of 6 ft.
(1.8 m). For example, with permeable soil and an average groundwater
head of 12 ft (3.7 m) , the 200 gal/mi/in-dia/day (185.2 1/km/cm-dia/day)
infiltration allowance should be increased tos
200
-
or 282 gal/mi/in-dia/day (261.1 1/km/cm-dia/day).
Many test sections in a system can be expected to show very
little leakage. The average in a project after all test sections have
been repaired to conform with infiltration limits should always be
substantially less than the maximum allowed per test section. Since it
is the averagB project infiltration that bears on treatment and pumping
costs, it may be appropriate to apply a limit to average project infil-
tration which may be two-thirds or less of the allowance per test
section. Otherwise, defects would be permitted to remain that should
be corrected to insure the soundness of the system with respect to root
growth and other maintenance problems.
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Exfiltration —
Exfiltration limits to achieve similar control of infiltration should
be set somewhat higher than the infiltration limits, since the specified net
test head provides a fully effective hydrostatic pressure of the pipe joints
which is not likely to be the case for infiltration testing. In addition,
the movement of water out of a pipe is likely to -be less impeded than the
movement of soil-fines laden groundwater into the small defects which these
tests are intended to detect. Accordingly, the combined leakage from the
pipe and manholes could be fixed at about 200 gal/in. -mi/day (185 1/cm-km/
day) when the average head on the test section is 3 ft (0.9 m). For other
head conditions the leakage allowance should be adjusted in direct relation-
ship to the ratio of the square root of the average test head to the square
root of the base head (3 ft (0.9 m)). For example, with an average test head
of 8 ft (2.4 m) the allowable exfiltration allowance should be:
200 x
= 327 gal/mi/in. -dia/day (303 1/km/cm-dia/day)
Manholes may be tested separately and independently. An allowance
for manholes of 0.1 gal/hr/ft-dia/ft/head (0.04 1/hr/cm-diam/m/head) would
be appropriate.
Low Pressure Air Testing —
Because of the cost and inconvenience of exfiltration testing with
water, and problems associated with steep grades, air pockets in house
lateral stubs, if used, and other factors, acceptance testing with low
pressure air has come into widespread use. Leakage limits have been adop-
ted which in general locate the same type of defects that are found by water
testing; but, it should be understood that no direct mathematical correlation
has been found applicable between air test limits and water exfiltration
limits. " ~~ ~~~
Air test allowance in use around the country generally follow, or are
similar to, the criteria developed in California by Ramseier and Riek (3).
These criteria were developed for wetted clay pipe and were found to be
applicable to wetted concrete pipe through independent research by Duff in
Seattle (4). The test has been widely and successfully used in testing
smaller diameter pipe, but it is becoming apparent that modified criteria
may be needed for sizes between 18 and 30 in. (45.72 and 76.2 cm). (Pipes
larger than 30 in. (76.2 cm) are more conveniently accepted by use of indi-
vidual joint testers).
Appendices B and C illustrate adaptations of the Ramseier-Riek cri-
teria which in brief provide that when the tested line is at 3 psi (0.21 kg/
cm2) average gauge pressure, the rate of leakage shall not exceed 0.003 ft3/
min/ft2 (9 x 102 1/min/m2) of internal pipe surface, or 2 ft3/min (0.94 I/
sec) when the computed rate is less that 2 ft3/min (0.94 I/sec).
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In 1975, the American Society for Testing and Materials (ASTM) approved
for the first time a tentative recommended practice, "Low-Pressure Air Test
of Vitrified Clay Pipe Sewer Lines 4 to 12 in. (10.16 to 30.48 cm)," designated
C 828-75T. It contains much of the Ramseier-Riek criteria, including an
allowable air loss of 0.003 ft /min/ft 2(9 x 10 2 1/min/m 2) of internal pipe
surface and a minimum of significant air loss per test section of 2 ft /min
(0.94 I/sec), but adds a new provision; the total allowable air loss shall
not exceed 3.5 ft 3/min (1.64 I/sec) in any test section. Procedures and a
table of holding times based on the equations from ASTM C 828, are shown in
Appendix C. Holding times have been expanded to include pipe through 24 in.
(60.96 cm) diameter and are applicable to vitrified clay pipe.
Plastic, asbestos cement, and other non-air permeable pipe should be
subjected to criteria more appropriate to those materials. Concrete and
clay pipe, if saturated, is essentially non-air permeable and should be tested
accordingly.
There is currently no general agreement as to what criteria are
appropriate (for non-air permeable pipe) but these references indicate
something in the range of 3 to 4 times the time required for pressure
drop in air permeable pipe.
Although air test results do not relate directly to alternate water test
criteria, and although criteria for testing are not yet firmly established,
there is no question that the method has resulted in significant improvement
in sewer construction, if only because the cost and convenience advantages
have made it practical to test much more footage of installed pipe than had
been tested with water.
Large Pipe
Pipe that is large enough to permit personnel to conduct interior
inspections can be accepted on the basis of such inspection, plus testing
of individual joints. A typical joint testing device isolates the joint,
fills pipe with air or water and is pressurized. The rate of loss is then
measured. Allowable leakage is usually the computed rate per foot of
pipe times the distance between joints. In practice, however, it is a
go or no-go test. The joint is generally either essentially bottle-tight
or it leaks badly enough to require repair.
As a go/no-go test, air may be used directly in individual joint
testing. A very slow drop of a needle indicates a good joint, and a
rapid drop indicates a defective joint. However, testing conditions are
very different when lines are tested and the Ramseier-Riek or other criteria
cannot be used to derive timed pressure-drop criteria for a joint test.
It should be recognized that any of these criteria, properly
enforced, will result in high quality construction and the difference
in actual infiltration, resulting from use of one limit rather than
another, should be relatively small.
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Appendix C has been adapted from the Indiana State Board of Health
draft regulations on methodology for leakage testing,
Obstruction-Proof Testing
Following the placement and consolidation of backfill and prior to
the placement of permanent ground cover and/or roadway resurfacing, a
test should be made to ascertain freedom from obstructions such as
excessive pipe vertical ring deflections, joint offsets, lateral pipe
protrusions into the sewer main, and accumulated debris..
All material, equipment and labor to perform such testing should be
provided by the construction contractors Testing equipment, systems and
procedures should be in accordance with the direction of, and used only
after approval of, the engineer.
Obstructions should be removed and all other conditions should not
exceed five percent of the nominal inside diameter of the pipe being
tested,, Soil consolidation rates depend on variable conditions such as
soil characteristics, moisture content, compaction procedures, depth of
trench cover, and rate of installation,, Because of these time dependent
variables, it is advisable that obstruction-proof testing be one of the
final acceptance criteria for the completed project. A suggested minimum
time lapse following installation might be six months, although soil
settlement may continue more than one year.
Either mandrels, solid cylinders, or balls with diameters of 95
percent of the specified pipe diameter may be used to test for obstruc-
tions .
Deflection Testing of Flexible Sewer Pipe
While many factors will influence the extent of deflection of an
installed flexible sewer pipe, a major factor is the soil density on the
sides of the pipe. Thus, a test for excessive deflection after completion
of installation work provides for a simple way for checking the quality
of the installation of flexible pipe. Testing may be accomplished by
pulling a go/no go mandrel, sphere or other device through the pipe.
To permit the pipe/soil system to attain initial 'equilibrium,' testing
for initial deflection is generally not done sooner than 30 days after
final backfilling and compaction.
At times, only a few selected portions of the system may be tested.
More extensive, or even complete system testing may be called for
depending on initial results. Deflection testing is sometimes not
required when upon the judgement of the design engineer the combination
of pipe properties, installation procedures, loading conditions and job
inspection procedures ensure compliance to the set requirements.
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The maximum allowable initial pipe deflection is set by the designer,
in consideration of:
o Initial pipe roundness;
o Pipe stiffness;
o Anticipated pipe loading;
o Pipe installation technique including soil, compaction, etc.;
o Small amount of additional deflection that may continue before
final stabilization of the pipe soil/system; and
o Safe ultimate deflection for the particular pipe specified.
Maximum specified allowable initial deflection values range from
under 5 percent to as high as 10 percent of the initial theoretical round
pipe diameter. Largely based on experience with flexible metal pipes,
5 percent has been accepted as the limitation for initial deflection for
many plastic piping products.
For flexible products such as PVC sewer gravity piping which are
capable of large ultimate deflections without structural damage some
designers and authorities permit somewhat more liberal requirements.
A few states permit up to 7 percent initial deflection and one is known
to allow as high as 10 percent. In other states, authorities and engineers
will specify 5 percent but relate it to the pipe's initial vertical non-
deflected diameter which, in effect, because flexible pipes tend to be
slightly out-of-round when unloaded, can be roughly equivalent to as much
as 7 percent relative to the diameter of perfectly round pipe.
Any section of pipe that is found to exceed deflection requirements
is corrected, or replaced, depending on pipe materials.
The ASTM recently surveyed users and specifiers of flexible pipe
and found almost 90 percent of those who replied specified 5 percent
or less, and that 10 percent was the maximum deflection being specified
by those surveyed.
Inspection of Construction
The importance of adequate inspection during construction cannot
be overemphasized,, Material, time and money usually can be saved by
supplying a fully trained inspector for all phases of sewer construction
projects. Deliberate malpractices and unintentional mistakes can result
in contravention of the designer's intent and jurisdiction's desire to
provide a sewer system of dependability and long life,,
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An alert inspector pays dividends by requiring strict adherence to
job standards, but he should not assume so active a role in the project
that he preempts the supervisory direction of the contractor. If the
contractor does not have adequate supervision on the job, the inspector
should report this to the contracting authority and the project should
be suspended until such srjpervisory personnel are available0 The
inspector and the field engineer logically may be asked to interpret
specifications, but they cannot assume direction of, or responsibility
for, the contractor's forces. If too many questions arise about the
plans and specifications, the design engineer should visit the site and
reassess the adequacy of these documents„ The need for this type of job
contact affirms the need for the design engineers, whether employed by
the jurisdiction or by a consulting engineering firm, to keep in touch
with the project during construction,. The inspector should not be
expected to make engineering design decisionse
The inspector should have basic responsibilities for adherence to
specifications, the accounting or verification of quantities of material
supplied, and time spent on the project,, He should be provided with a
log book and whatever other forms are necessary to produce an adequate
record of all activities of the contractor's forces. He should observe
and record weather conditions and all other occurrences and conditions
that affect the quality of workmanship. It is not necessary that the
inspector be a licensed professional engineer, but he should report to
a professional engineer who should appear on the job frequently enough
to answer all questions of the inspector or contractor. .The consulting
engineer or the municipal design engineer should recognize that construc-
tion is the ultimate realization of his plans. He should be well repre-
sented during this crucial period.
During the course of interviews the best inspectors were often
described as retired contractors or former job superintendents who pro-
vide maximum practical experience and knowledge. They are familiar with
all of the "tricks of the trade," both good and bad. They speak the
language of the workers and engender respect because they know what they
are talking about.
Testing for Acceptance
Acceptance testing and inspection are at times confused and con-
sidered to overlap; however, it should be made very clear that these are
two separate quality control functions. Each may depend on the other
but neither can substitute for the other. Although many engineers depend
on criteria other than resistance to leakage as controlling factors in
the design and construction of sewerss the chief method of guaranteeing
a properly installed and workman-like job has been the use of leakage
tests as a basis of acceptance.
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The job specification should clearly indicate the party (owner or
contractor) responsible for performance of the tests, the time schedule,
and the manner and method of payment if testing is to be done by the
contractor. All acceptance testing should be done under the supervision
and responsibility of the project engineer.,
Although contractors may choose to conduct leakage tests before
backfilling, for their own assurance, it is very important that the
actual acceptance testing be delayed until after backfilling and com-
paction has been completed,, Many if not most of the defects which become
sources of leakage and other problems are caused by loading imposed during
backfill and compaction„
Infi1trati on Testing
If conditions suitable for direct measurement of infiltration exist,
measurement is usually accomplished by blocking off the inflowing lines
at the upper manhole and damming the pipeline at the inlet to the lower
manhole. Because leakage allowances are very small, measurements are
best made by timing the filling of a small container of known volume,
or by directing flow into a plastic bag for a specified time, then
measuring the content. A sheet metal dam with a spout can be readily
devised and sealed in position with any convenient mastic material.
Except where manholes are very closely spaced, measurement should
not be attempted on runs longer than manhole to manhole. Otherwise,
defects that ought to be found and corrected may be missed because
their effect is masked by an acceptable over-all leakage rate.
Exfiltration Testing
Exfiltration testing consists of filling the test section with
water, pressurizing by filling the upstream manhole or a standpipe
with water, and then, after allowing time for absorption into the
manhole or pipe walls, measuring the rate of loss. The upstream
manhole may serve as the standpipe, in which case the manhole leakage
is measured together with the pipe leakage. Or, the standpipe may be
a small diameter pipe with a container of a gallon or so capacity at the
top in order that leakage during the timed period will occur without
significant loss of head. When this procedure is followed, manholes
should be -tested separately. Their contribution to total infiltration
can be signficant.
As with infiltration testing, test sections should be limited to
manhole-to-manhole, to avoid missing unacceptable defects. The length
of the test section may also be limited by maximum acceptable head at
the lower end, typically fixed at 15 to 20 ft (4.6 to 6.1 m). The test
head at the upper end should be at least 2 ft (61 cm) above the top of
the pipe, or above existing groundwater level, whichever is higher, and
should not be less than the maximum probable in-service groundwater head.
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Provision should be made for bleeding off the air that may be trapped
in plugged service lateral stubs. If trapped air is not removed, its
leakage through defects or through the walls of air permeable pipe will
result in a false measurement.
A disadvantage of testing by exfiltration lies in the problem of
finding the necessary water and then disposing of it. Furthermore,
when a serious defect exists, the amount of water leaked into the trench
may complicate the dig-up and repair.
Air Testing
Low pressure air testing may be accomplished by measuring the rate
of air inflow required to hold the test section at a uniform pressure,
or by timing the rate of pressure drop in the test section. The timed
pressure drop procedure requires less sophisticated equipment and is in
most common use. A description of the equipment required, and a detailed
step by step test procedure is given in Appendix B.
Criteria is commonly given in terms of rate of air loss at a uniform
pressure. In adapting to the timed pressure drop procedure, it is
customary to assume that a 1 Ib (0.45 kg) drop, from 0.5 Ib (0.27 kg) above
the specified test pressure to 0.5 Ib (0.27 kg) below, provides a comparable
average pressure condition. The volume of atmospheric air that would be
lost during a 1 Ib (0.45 kg) drop in pressure would be £7—7" times the
volume of the test section. This volume, divided by the prescribed maximum
rate, would be the minimum time required.
For example, if the criteria calls for a maximum rate of loss(R)of 3.5
cfm (0.1 m3/min) at 3 psi (0.2 kg/cm2) pressure, and the test section
comprises 300 ft (91 m) of 12 in. (30 cm) and 200 ft (61 m) of 6 in.(15 cm)
the minimum time would be computed as followsr
V =
L x A =
x 300 ft x if x 0.5 ft = 18.7 ft"
R = 3.5 ft /min
18.7 ff
= 5,34 minutes
R 3.5 ft3/min
Where: V— Volume to be filled; R = Rate of loss of air; and T = Time.
If a head of groundwater exists above the pipeline section to be
tested, the air test pressure must be increased an offsetting amount.
However, if any service connections included in the test extend above
groundwater, it must be recognized that these portions of the test
will be subjected to the full gage pressure. This will affect the
rate of leakage and may result in a false measurement. Such increas-
ed pressure also increases the already substantial hazard of plugs
blowing out. PLUGS SHOULD BE CAREFULLY BLOCKED. WORKMEN MUST BE
KEPT OUT OF THE MANHOLES WHILE THE SYSTEM IS UNDER PRESSURE.
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Manhole Testing
No practical means has been found for air testing of manholes,,
They must be tested separately when the lines are accepted on the
basis of air testing. Manholes may also be tested separately when
exfiltration tests are used to determine acceptability of the sewer
lines. The procedure is inconvenient but not complicated: plugs must
be inserted in all the connecting pipes (which must later be removed
under water). The manhole is then filled to the required test depth
which should be to at least the elevation of probable highest ground-
water level. After a suitable time for normal absorption the manhole
is refilled to the test level. Then timing is begun and at the end
of a measured time period the amount of water required to refill the
manhole to the test level is measured.
Still Photography
Photography, including colorslides, stereo-photos, etc., can
provide a record of the condition of new sewer lines. Its use is
primarily for new construction since line conditions generally allow
an adequate view of defects as is true with TV inspection. It serves
as an aid to the inspector by providing a record of sewer construction
workmanship. It may reveal faulty joints or broken pipe.
TV Inspection
Television inspection is a method for observing the condition of the
interior of sewer, pipe. For new pipes, television detects cracks and
other defects not detected by other means of observation or testing be-
cause the defect had been packed with clay during backfilling. Efforts
have been made with some success to estimate actual infiltration flows
observed in television studies. TV is also useful in the detection and
eventual correction of infiltration problems in existing sewer systems.
After building sewers have been connected, and the sewer is in use,
infiltration, exfiltration, and air testing cannot be used. TV appears to
have the following advantages:
a. Instantaneous viewing is possible. If a sewer line, new or
old, cannot be viewed, this is immediately discernable.
Where lines are restricted, causing sand or other debris to
cover the lens of the camera, flooded dips in the lines,
misalignments, and other such deficiencies can be determined
immediately.
b. "Development of Pictures" is not necessary. Therefore, there
is no delay in making a decision especially where time is of
essence.
c. Several people can "view the line" together on the spot. In
addition it is possible to take video recordings off the
screen in order that permanent records can be made. Sound
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records onto the video tape are made at the time of recording
to specifically identify the place, the time, and the conditions'
found. This saves unnecessary narration or eliminates later
questions as to defect location or conditions. Instant or
35mm camera pictures may also be made of the TV picture as a
permanent record.
d. With the use of TV it is possible to limit picture records to
specific defects and those areas that typify the. general
condition of pipe free from defects.
e. TV provides the only means by which moving water can be observed.
In addition, water of infiltration from house services that are
noted to be running can be properly evaluated by TV viewing.
When a house service is noted as running, a check of the
building itself is possible to determine whether the flow is,
in fact, domestic flow or water of infiltration.
TV has certain disadvantages:
1. Equipment operation requires operators with a good
overall mechanical and electrical knowledge.
2. Evaluation of TV reports, especially in the case of
infiltration studies, requires the services of a
skilled or specialized professional engineer if optimum
results of the study are to be achieved. Figure 22
shows a typical unit.
Source: Cherne Industrial, Inc.
Figure 22. Typical TV camera with packer unit.
Smoke Testing
Smoke is not an acceptable method of detecting all infiltration
pointso However, it has been extensively used to locate sewer cracks,
defective joints and direct connection of a sanitary sewer to a storm
sewer0 In such cases, a smoke generating unit is placed in a manhole
with a blower, and the smoke can be observed coming out of the soil
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wherever there is a leak. Driving a rod through soil near points of
suspected leakage has been found useful in providing a passage for
concentrated smoke discharge to the surface.
It would appear to be a method that has limited application on
lines that are seriously damaged or have been installed very poorly.
Smoke tests are useful in locating sources of inflow waters which
enter sewer systems through pipe connections which are not trapped
such as roof downspouts. Where a high-water table is present, the
smoke will be absorbed by the overlying water. A blower set up over
a manhole is shown in Figure 23. The number of sources determined is
directly affected by the procedure used. Slight technique changes may
change the number of sources found by a factor of 3 to 8.
Source: Superior Signal Company, Inc., Spotswood, New Jersey
Figure 23. Smoke testing blower set-up over manhole.
Visual Observations
In large size sewer lines, and also by the use of certain types
of mirrors and lights in smaller sewers, it is possible to inspect
visually certain pipe lines. Except in the case of large size pipe
it would appear that other methods of inspection are more productive.
In any case, this is not a quantitative test of sewer conditions.
Conditions for Acceptance Tests
Another aspect of testing is the final acceptance of a sewer line
after construction. It is almost a universally accepted fact, although
not always so practiced, that new sewer construction should be tested
and accepted in as short sections as feasible. It becomes extremely
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difficult to assign responsibility for correction of new sewer lines
if building connections have been installed as standard tests cannot
be used.. In addition, the crucial role of the building sewer must be
taken into consideration; the sewer contractor cannot be held liable
for any inadequacies of plumbing contractors who usually lay at least
part of the building connection line. If new sewer lines are tested
for final acceptance section by section and before connections are
made, the sewer contractor can be held responsible for excessive infil-
tration rates which are found and evaluated by eff ective meihods of
testing.
Corrective Measures
Testing prior to acceptance may indicate that sections of the
system do not meet the required infiltration standards. The decision
then must be made as to whether or not the defective sections must
be excavated and replaced or repaired, or whether internal sealing
will be allowed. Where the defects are not extensive, internal seal-
ing generally will tighten up the pipe to meet specifications.
Excavation, on the other hand, often results in the breaking of
adjacent joints.
The feeling that an internally sealed pipe is "less than new"
has led to the replacement of defective sections. However, a real-
istic evaluation of the costs, problems, and possible additional
effects on the pipe may indicate that the project specifications
should require or allow the contractor the option of such sealing for
minor defects when in the opinion of the inspecting engineer there
are no structual deficiencies in the barrel of the pipe. Internal
pipe grouting can be a permanent solution if the technique is
applied in accordance with engineering principles that consider the
type of soil being grouted and the nature of the defects being
evaluated»
Building Sewer Standards
Jurisdiction and Control--
Building service conduits often represent a vital gap in regu-
lation and control. The portion of the building sewer between the
structure and the property line constitutes one part of the connection,
while the portion between the property line and the public sewer in
the street line completes the connection. Reference is made to these
two portions of building sewers because separate parts have been
constructed and connected under the control and supervision of separate
governmental agencies. The connection to the building plumbing and
drain system that extends to the property line often is interpreted
as an extension of the structure facilities and is ordinarily installed
under plumbing or building code regulations with testing and approval
by plumbing officials or building inspectors. The section of the
building sewer between the property line and the street sewer, includ-
ing the connection thereto, usually is installed under sewer rules
and inspection; approval is by the public works or sewer officials.
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One exception to this rule of split authority often occurs in the
case of industrial waste connections. Because of the effect of such
wastes on sewer structures and treatment facilities, the entire length
of these building sewers may be supervised by sewer officials . This
procedure gives them better control of such connections and the intro-
duction of wastes, when ruled to be amenable to sewer transportation
and treatment.
Building sewers play a vital- role in the overall infiltration and
inflow volumes carried by separate sanitary and combined sewer systems,
This split in authority impedes total control over building sewer
construction, testing and acceptance under present circumstances when
unified action is most needed. Contributing to potential entry of
infiltration into sewer systems are the following factors: a) rela-
tively short lengths of house or other building sewer runs, b) the
multiplicity of these lines in a given stretch of collection sewers
in heavily built-up urban areas, and c) that each house sewer run
has three possible physical connection points—-at the building line,
at the property line, and at the junction with the public sewer.
If possible, one control agency should be responsible and super-
vise the building sewer as a single source of infiltration.
Codes, Construction and Testing.--
Regulations governing building sewers are often contained in
building or plumbing codes. They represent a considerable range of
interest and control. Many codes make no reference to foundation drain
connections, although many make the distinction between the building
sewer and the building storm sewer. A number of codes still permit
various area drains to be connected to the building sewer.
Most plumbing codes permit a wide range of materials to be used,
although some of the most recent ones are more restrictive. A few
codes require the building sewer to be tested, usually by holding a
10 ft (3 m) head of water for 15 minutes with no allowable leakage.
Air testing is mentioned as a test procedure, mainly on the interior
system although the building sewer also can be tested. Smoke tests
also can be used as the pipe lies in the trench before backfilling
and connection to the lateral. Small defects are then readily
apparent.
Because of the potential severity of the infiltration and inflow
contribution of building sewers, they should be constructed of top
quality, watertight materials with thorough inspection and testing.
The physical connection to the street lateral sewer should be per-
formed by the sewer agency or department crews after careful train-
ing and inspection.
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REFERENCES
1.
2.
3.
4.
American Public Works Association Research Foundation, "Control
of Infiltration and Inflow Into Sewer Systems," EPA Publication
No. 11022, 121 pp, December, 1970.
American Society for Testing Materials - Standards: "Test for
Density of Soil in Place by Sand Cone Method," D#1556, 1968;
and "Test for Density of Soil in Place by the Rubber Ballon
Method," D#2167, Committee D18, 1966.
Ramseier, Roy E., and Riek, George C., "Low Pressure Air Test for
Sanitary Sewers," Journal of the Sanitary Engineering Division
Proceeding of the American Society of Civil Engineers, #3883
SA-2, 29 pp, April, 1964.
Duff and Chase, Unpublished report given at the Pacific Northwest
Pollution Control Association, 1965.
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SECTION IV
APPENDICES
A.
B.
C.
D.
E.
F.
Description of Laboratory Test for Determination of Possible
Inflow Through Manhole Cover Pickholes and Seat Surfaces -
Source: Neenah Foundry, Inc.
Sample Air Testing Specification - Source: Low Pressure Air
Test for Sanitary Sewers by Roy E. Ramseier and George C. Riek,
from April 1965 issue "Journal of the Sanitary Engineering Division
ASCE."
Sewer Leakage Test Guidelines - Source: Adapted from Dr'aft
Regulations, Indiana State Board of Health.
Patterned Interview Infiltration/Inflow Analysis - Source:
Elson T. Killam Associates.
Manhole Inspection Check List - Source:
Associates.
Elson T. Killam
Standards for Selected Sewer Pipe and Appurtenances - Source:
American Society for Testing and Materials (ASTM).
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APPENDIX A
DESCRIPTION OF LABORATORY TEST FOR DETERMINATION OF POSSIBLE INFLOW
THROUGH MANHOLE COVER PICKHOLES AND SEAT SURFACES
(Source: Neenah Foundry Company, Inc.)
Purpose;
With,the current strong emphasis on matters of ecology, the
controlling agencies such as EPA are moving for complete sewage treat-
ment. Many times this requires the addition of new treatment facili-
ties; however this investment might not be required to such a great
extent if infiltration and inflow in sanitary sewers could be at
least partially eliminated.
It has been known for some time that considerable amounts of water
enter through manhole covers by way of open pickholes, bearing surfaces,
and so forth. The amount of course has not been known. The purpose
of this test was to determine how much water can enter a manhole cover
through the surface.under varying conditions.
Material Tested and Procedure;
Seven different cover types and bearing surfaces were involved
and on each, three separate tests were conducted. Listed below are
the types of covers tested and their corresponding bearing surfaces
which have been identified with a type number.
Type of
Cover
3
4
Description
R-1040 non-rocking, Type "B" Lid, with two open pickholes
measuring 1.25 x 1.5 in. (3.2 cm x 3.8 cm).
R-1040 non-rocking, Type "B" Cover, with two concealed
pickholes.
R-1040 Machined,, Type "B" Lid, with two concealed pickholes.
R-1040 machined., Type "B" Lid, with two concealed pickholes
and sealed to frame with flat rubber gasket measuring
about 0.125 in. (0.3 cm).
R-1040 machined, Type "B" Lid, with two concealed pickholes
and sealed to frame with liquid type gasket similar to
roofing cement.
R-1040 machined,, Type "B" Lid, with two concealed pickholes
and sealed to frame with "0" ring gasket.
R-1040 non-rocking type lid with an unmachined bearing
surface and a 0,25 in. (0.6 cm) diameter N'eoprene gasket
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inlayed in the manhole lid.
All or some of the above covers were tested under four different
conditions which will be described as conditions A, B, C, or D.
Condition A
Water was injected into the testing tank so that it rose above
the top of the frame by about 0.063 in. (0.2 cm) and thereby covered
the lid and flowed through the pickhole and through the bearing surface
simulating a surface type drainage.
Condition B
Described as top surface drainage and accomplished
by spilling water through the inlet pipe directly on the top of the
cover similar to a heavy rainfall on the cover itself. This test
varied from the "A" condition in that Test "A" had water introduced
into the tank on the outside of the frame.
Condition C
Cover inundated with 1 in. (2.54 cm) head. The tank was filled
so water covered the lid by 1 in. (2.54 cm) creating some additional
flow pressure.
Condition D
5.5 in. (14 cm) head allowed to run down to zero.
Results
The test results by cover and type of test are shown, in
Table A-l. Values are shown in gallons per minute. In cases
where the term "insignificant" is written, an almost immeasurable
amount of leakage occurred. On tests where the reference "no test"
is shown, it was felt that a test under these conditions was not
necessary.
In addition one other test was conducted using a R-1040 Type
"B", machined lid with two concealed pickholes and a flat rubber
gasket. This was tested with a 3.5 in. (8.9 cm) head receding for
60 seconds resulting in leakage of 4 gal (15.1 1) per minute. It was
discovered, however, a leak had occurred between the frame and the
gasket seal in the tank which made the test inaccurate.
Conclusions
Tests definitely prove that the type of cover and pickhole
determine the amount of inflow. By using different sealing methods
such as flat or "0" ring gaskets or even sealing compoundj, space
between cover and frame can be made almost watertight without bolting
or other pressure devices normally used on watertight manhole castings.
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APPENDIX B
SAMPLE AIR TESTING SPECIFICATION
(Source: Low Pressure Air Test for Sanitary Sewers by Roy E. Ramseier
and George C. Riek, from April 1965 issue "Journal of the Sanitary
Engineering Division ASCE).
It is recommended that the Specification for the Air Test
consist of two parts: The Presumptive Test and the Acceptance Test.
The Presumptive Test
The contractor may low pressure air test the line before back-
filling the trench to aid the contractor in checking the installation
for any defects and proper workmanship. This test is at the option
of the contractor.
The Acceptance Test
The contractor shall test the line as prescribed in the specifi-
cations by the engineer or agency after the backfilling has been
completed.
Recommended Air Test
The contractor shall furnish all facilities and personnel for
conducting the test under the observation of the engineers. The
equipment and personnel shall be subject to the approval of the
engineers. The contractor shall clean the line before proceeding with
the air test. All debris shall be removed at the first manhole where
its presence is noted. In the event cemented or wedged debris or a
damaged pipe shall prevent cleaning, the contractor shall remove the
obstruction. The pipe or sections of pipe to be tested should be
wetted before the air test is started.
Immediately following the pipe cleaning and wettings the pipe
shall be tested with low pressure air. Air shall be slowly supplied
to the plugged pipe installation until the internal air pressure
reaches 4.0 psi (0.28 kg/cm2) greater than the average back
pressure of any groundwater that may submerge the pipe. At least two
minutes shall be allowed for temperature stabilization before proceed-
ing further. The rate of air loss shall then be determined by measur-
ing the time interval required for the internal pressure to decrease
from 3.5 to 2.5 psi (0.24 to 0.18 kg/cm2) greater than the average
back pressure of any groundwater that may submerge the pipe.
The pipeline shall be considered acceptable when tested at an
average pressure of 3.0 psi (0.21 kg/cm2) greater than the average
back pressure of any groundwater that may submerge the pipe when the
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section under test does not lose air at a rate greater than 0.003 ft /
min/ft2 (0.09 nrVmin/cm^) of internal pipe area except that the minimum
allowable rate of loss for the section shall not be less than 2 ft^
(0.06 m^) per minute.
The requirements of this specification shall be considered satis.-
fied if, during the time as computed according to the attached page
entitled "Recommended Procedure for Conducting Acceptance Test", the
pressure in the pipe line does not drop more than 1 psi (0.07 kg/cm^)
below the initial pressure of 3.5 psi (0.24 kg/cm^) greater than the
average back pressure of any groundwater head that may submerge the
(pipe) line.
The acceptance test shall be made for each first section of line
constructed, for every first reach of line installed where a new sewer
crew is used, or wherever the engineer may direct. The contractor
shall not preceed with any construction until the prerequisite of meet-
ing the successful installation of each section is made, as mentioned
above, to qualify the crew and/or material.
If the pipe installation fails to meet these requirements, the
contractor shall determine at his own expense the source or sources of
leakage, and he shall repair or replace all defective materials or
workmanship. The completed pipe installation shall meet the require-
ments of this test, or the alternate water exfiltration or infiltration
test before being considered acceptable.
Safety Provisions
The plugs must be firmly secured and care should be exercised in
their removal. The total force on a 12 in. (30.5 cm) plug at 4.0 psi
(0.28 kg/cm^) is over 450 Ibs (204 kg). Care must be exercised in not
loading the sewer line with the full pressure of the compressor. Keep
men out of manholes until the pressure has been released. If water
leaks into the line after the plugs are installed and floods the air
inlet and the needle on. the air pressure indicates zero then possibly
the water column has balanced the air pressure in this instance and
care is necessary in releasing the pressure. If testing below ground
water level; inject the air at -the upper plug and/or turn the inlet
up as with a water test apparatus.
133
-------
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APPENDIX G
SEWER LEAKAGE TEST GUIDELINES
(Adapted from Draft Regulations Indiana State Board of Health)
Presented herein are recommended methods for conducting water
leakage tests of sanitary sewers by the infiltration/exfiltration test
and by the low-pressure air test.
INTRODUCTION
There are three methods of sewer test methods, and the choice of
method is mainly dependent on the groundwater conditions surrounding
the section of sewer to be tested. In the following discussion, the
method for determining the groundwater table (rarr) and the choice o*
leakage test method will be described. In addition, the recommended
method for performance of a leakage test on system manholes is des-
cribed.
Procedure for Determination of Groundwater Level
Groundwater table should be measured either at a manhole or at a
pipe section between two manholes:
GWT measurement at a Manhole—
In areas where a high groundwater table is known to exist the
contractor shall install, during the sewer construction, a °-5 in.
(1.27 cm) diameter capped pipe nipple, approximately 10 in. (25.4 cm) long,
through the manhole along the top of the sewer. If this length of
pipe is not installed during construction, the contractor will drill
a hole through the manhole to permit installation of this pipe.
Immediately prior to performance of the Leakage Test:
a.
b.
c.
d.
Remove the pipe nipple cap.
Blow air through the 10 in. (25.4 cm) length of pipe with
sufficient pressure to clear the line.
Connect a clear plastic tube to the pipe nipple and raise it
vertically along the manhole wall.
After the water has stopped rising in the tube, the height
in feet of water over the crown of the pipe shall be taken.
135
-------
GWT Measurement at a Pipe Section—
Insert a pipe probe, by boring or jetting into the backfill
material adjacent to the center of the pipe at the midpoint of the
sewer section under test and determine the pressure in the probe
when air passes slowly through it. The pressure value, expressed in
psi should be multiplied by 2.31 to determine that static head of
water over the pipe.
Selecting Leakage Test Method
In the presence of groundwater the following condition will decide
which test should be conducted.
The infiltration test will apply only where the groundwater table
is above the crown of the pipe by a minimum head of 2 ft (61 cm). (This
measured head must be existing at the highest point of the section of
sex
-------
An exfiltration test shall be conducted in accordance with the
above description unless the groundwater table is at or above a level
one-half the depth of the manhole. In this rare case an infiltration
test will be conducted by including the manhole in the section of
sewer to undergo test. In other words, the allowable infiltration for
a section of sewer which is below the groundwater table to such an
extent that the upstream manhole is also more than half submerged
shall be tested by installing the water tight plug in the influent
sewer line to the manhole and including the allowable infiltration
from the manhole with the amount calculated for the sewer system.
Field data shall be recorded on Form A, Manhole Leakage Test Data,
and submitted for approval.
PROCEDURE FOR CONDUCTING AN INFILTRATION TEST
Clean the pipe section (manhole to manhole reach of sewer) being
tested by propelling a snug-fitting inflated ball, or other adequate
method, through the pipe with water.
Determine the groundwater table (GWT)„ (See procedure above).
The GWT shall be noted for the section of line undergoing test and
included with the test results submitted to the State Board of Health
for each section of line tested.
Plug the upstream pipe outlet from the manhole with a plug which
will assure a tight seal against flow from upstream portions of the
sewer system. To assure a tight seal, the plug shall be at least a
length equal to the diameter of the pipe section undergoing test.
Install a weir in downstream manhole of section undergoing test.
The following discussion is intended to provide the contractor and
engineer with established criteria for placement and accurate reading
of the weir.
a. The type of weir used shall be noted. Weirs are classified
according to the shape of the notch (i.e. rectangle, trapazoid
or triangular most often called V-notch).
b. Since the most common weir employed for sewer testing is a
90° V-notch weir, procedures and items will be outlined
affecting a valid test. If another weir type is to be used,
the engineer must submit similar information in the project
specifications.
c. Weir must be installed in its proper position; plumb and
tight to the pipe wall surface.
d. A definite period of time shall be included in the specifica-
tions denoting the allowance for infiltrated waters to crest
the weir. A one hour period is recommended for sufficient
137
-------
FORM A - MANHOLE LEAKAGE TEST DATA
1. Municipality:,
2. Project Inspector:
3. Date of Test:
4. Location of the Manhole:
5. Depth of Manhole from Ground:_
6. Size(s) of pipe(s) connected:
feet
inch
7. Groundwater table (GWT) measurements:
a. Method Used: ._
b. GWT elevation: feet from the top of the manhole
8. Water level after filling the manhole feet inch from top
at the beginning feet inch from top
at the end feet. inch from top
time elapsed_
hour(s)
9. Diameter of the manhole where the water level was measured:
feet inch
10. Total volume lost:_
11. Leakage Rate:
12. Manhole: pass
_gallons
gallons/hour/manhole
/ / fail / /
138
-------
water to build up behind the weir with the eventual over-
flow or cresting of weir, at a!' constant rate.
The head (H) of water flowing over the weir must be measured
accurately and the measurement taken at least 18 in. (46 cm)
upstream from the crest of the weir or three times the
height of H, whichever is greater.
Discharge over the 90° V-notch weir shall be calculated
according to:
Q = 3240 H
2.5;
H in inches, Q in gallons per day
The infiltration test shall be performed by the contractor
at his expense in the presence of the engineer, or his
authorized agent, after completion of construction, back-
filling, compaction and prior to placement of pavement.
When there is significantly more than two feet of ground-
water table above the top of the pipe at the highest point
in the section being tested, ten percent additional infil-
tration above the required 200 gal/in.-dia/mi/day (185.2 I/
cm-dia/km/day) limit will be allowed for every 2 ft (61 cm)
of additional head.
Field data shall be inserted on Form B. "Infiltration Tfest
Data," for the infiltration test.
PROCEDURE FOR CONDUCTING AN EXFILTRATION TEST
Prior to initiating an exfiltration test the level of groundwater
adjacent to each section undergoing test must be determined. The
exfiltration test works on the basis that a certain pressure will force
water out of the line into the soil surrounding the pipe. If the
groundwater level is above the crown of the pipe measured from the
highest elevation of the sewer the infiltration test is the preferred
test method.
Clean the pipe section (manhole to manhole reach of sewer) being
tested by propelling a snug-fitting inflated ball, or other adequate
method, through the pipe with water.
Plug the downstream pipe outlet to the manhole with a plug
which will assure a tight seal against water leakage from the upstream
water. To assure a watertight seal the plug shall be at least a
length equal to the diameter of the'pipe section undergoing test.
Exfiltration test is based on the loss of water from the section
of sewer being tested; therefore, the method of imposing a specified
pressure head on the system must be described. Also just as impor-
. 139
-------
FOBM B T. IJNFI^TRATION TEST
1.
2.
3.
4.
5.
6.
7.
8.
Municipal! ty; ^ ^
Project Name:
Location of Sewer:
Weather conditions;.
Test Start:
afm,
_p .m.
Pipe (was) (was not) cleaned by balling before test
Determination of groundwater table (GWT);
below pipe invert , at pipe wall above the crown
Describe how GWT was determined;
9. Sewer information;
diameter^.
length
10. Type weir used:_^_
11. Time elapsed for infiltrated water to crest weir
12. Head, H. measured ^ inches
13. Allowable infiltration fpr sewer section under test_
2.5
14. Actual loss calculated using 9 ^ 3240 H
15. System: pass /" / fail / /
16. Signature of Inspector _
jLnches
feet
min.
_gal
_gal
140
-------
tant, the volume of water necessary to impose this head must be
restricted to a calculated volume for each portion of sewer. The
allowable exfiltration is the same as specified for infiltration.
a. Methods for imposing pressure head on system
1. The upstream manhole may be used as a reservoir for
maintaining the pressure head. The head of water
shall be a minimum of 2 ft (61 cm)_ higher than the crown
of the pipe at the high point in the line being tested
or at least 2 ft (61 cm) above the existing groundwater
table, whichever is greater. Ten percent additional
exfiltration will be allowed for each 2 ft (61 cm) of
water head above the minimum value for conducting an
exfiltration test.
2. A standpipe may be used instead of the upstream man-
hole for providing the pressure head on the system.
The head of water shall not be less than 2 ft (61 cm)
nor greater than 15 ft (4.5 m) above the crown of the
pipe measured from the highest point in the section
under test. Use of the standpipe requires that the
pipe be refilled to maintain a constant pressure head.
The gallons added must be noted and reported as the
actual exfiltration.
3. The ten percent additional loss shall also apply
when the standpipe is used for providing the pressure
head.
After plugging the downstream manhole securely as explained in
procedure for conducting infiltration test, and after the method for
placing the necessary pressure head on the system is decided, water
may be added to fill the sewer and manhole or standpipe, whichever
is utilized.
a. The amount of water (volume needed to fill the sewer plus
the manhole or standpipe) shall be calculated for each
reach of the system.
Water shall be introduced from the upstream manhole and
shall be metered not to exceed the approximate volume
calculated by the engineer to completely fill the sewer
and manhole or standpipe.
This approximate volume of water should not be exceeded
because the excess water introduced is obviously leaving
the sewer through a leak or leaks and saturating the
surrounding soil. Once the soil surrounding the section
of sewer under test is saturated, less water will exfiltrate
from the system and the test results will be invalid.
141
-------
Water will be allowed to stand for a period long enough
to allow water absorption in the pipe. For some materials
up to six hours may be required depending upon the degree
of saturation prior to testing. After the absorption
period, the pipe shall be refilled to the established
measuring mark and the test begun.
Determination of the actual exfiltration is based upon the
method used for providing pressure head on the system,
either by standpipe or the upstream manhole.
1. Use of the standpipe requires that a constant water
level be maintained in the standpipe to keep the
specified pressure head on the sewer section under
test. Therefore, the volume of water added to the
standpipe over the one hour test period is the exfil-
tration from the section under test.
2. When using the manhole, exfiltration will be determined
by measuring the difference in original water elevation
from the final water elevation and converting to actual
gallons loss through the pipe after a one hour period.
If the line does not meet with the engineer's calculated
permissible loss, the section of sewer shall be unacceptable,
Another exfiltration test shall not be conducted until the
groundwater conditions surrounding the pipe return to a
condition similar to those existent at the beginning of the
test period. The groundwater elevation shall be determined
prior to initiation of the second test.
Field data shall be included on Form C "Exfiltration Test
Data" for conduction of an exfiltration test.
PROCEDURE FOR CONDUCTING A LOW-PRESSURE AIR TEST
Clean pipe to be tested by propelling a snug fitting inflated ball
through the pipe by water pressure or other adequate method. This step
is important because it not only flushes out construction debris, but
the water used to flush the ball through the pipe dampens the pipe wall.
The rate of air loss through pipe wall permeation can be significant on
dry pipes.
Plug all pipe outlets with pneumatic plugs having a sealing length
equal to or greater than the diameter of the pipe to be tested. The
pneumatic plug shall be able to resist internal testing pressures
without requiring external bracing.
The groundwater level surrounding the section of sewer under
testing shall be determined by one of the procedures previously out-
142
-------
FORM C - EXFILTRATION TEST DATA
1.
2.
3.
4.
5.
6.
7.
8.
Municipality:
12,
13,
Location of sewer:_
Weather conditions_
Test Start:
a.m.-
_p.m.
Pipe (was) (was not) cleaned by balling before test.
Determination of groundwater table (GWT):
below pipe invert at pipe wall above the crown
Describe how (GWT) was determined;
Sewer information:
diame ter inches
leng th
volume
feet
_cu ft, refer to exfiltration test discussion
9. Method used for imposing pressure head on system:
upstream manhole
standpipe
10. Saturation period of manhole and pipe:
11. Manhole used for imposing pressure head, complete following:
Initial water surface elevation feet inch
Pressure head on system psig
End water surface elevatiori_
Elapsed time for test
feet
inch
Diameter of manhole where water levels were measured
Volume water loss gallons
Actual exfiltration rate gpd/inch/mile
Standpipe used for imposing pressure head, complete following:
Pressure head imposed on system feet inch >
Gallons added during test period
Exfiltration rate
Decision of inspector:
Signature of inspector_
gallons/inch-dia/mile/day
pass , fail
Date
143
-------
lined in the introduction. If the groundwater table is above the pipe
then test pressures shall be increased by the corresponding increment.
(e.g. if the groundwater table is 1 ft (0.3 1) above the lowest crown of
the pipe, the air pressure should be increased by 0.43 times each foot
(0.3 1) of water.
Once the pipe outlet plugs are securely in place, pressurized air
is introduced to the system. The air shall be fed through a single
control panel with three individual hose connections as follows:
1. From control panel to pneumatic plugs for inflation in
sewer pipe.
2. From control panel to sealed line for introducing the
pressurized air.
3. From sealed line to control panel. This line will enable
continous monitoring of the air pressure rise in the sealed
line.
The air shall be introduced slowly to the section of pipe under
evaluation until the internal air pressure is raised to 4,0 psig
(0.28 kg/cm ) greater than the hydrastatic pressure head created by
the existence of groundwater that is over the pipe section.
A minimum of two minutes shall be provided for the air pressure
to stabilize to conditions within the pipe. (This stabilization
period is necessary for variations in temperatures to adjust to the
interior pipe conditions). Air may be added slowly to maintain a
pressure of 3.5 - 400 psig (0.24 - 0.28 kg/cm2) for at least two
minutes. During the temperature stabilization period the stopwatch
should be made ready and the plugs, pipes, and hoses checked for
proper seal by spraying with a soap solution.
After the stabilization period, when the pressure reaches exactly
3.5 psig (0.24 kg.cm2) the stopwatch is started and when the pressure
reaches 2.5 psig (0.28 kg/cm2) it is stopped. If the time required
for a one pound pressure drop 3.5 to 2.5 psig (0.24 to 0.28 kg/cm2) is
not less than the allowable (see Table C-l) time for the pipe section
under test to lose air, the section shall pass the leakage test.
There are several methods for computation of allowable time for
the low pressure air test; however, for ease of computation and
establishment of stand time increments for varying diameter sewer
pipes of saturated, air porous material, such as unglazed V.C. and
concrete, the chart presented in Table C-l is applicable. Field data
shall be recorded in Form D, Air Test Data Sheet, for conducting a
low-pressure air test.
144
-------
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145
-------
FOEM D - AIR TEST DATA
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Municipality:
Location of Sewer:.
Project Name:
Description of Pipe Installation Under Test
diameter inches
length feet
Field Conditions
groundwater table level (GWT): below pipe/ / above pipe/ /
feet of head
determination of GWT: from manhole/ / pipe probe ]_ '/
other/ / (describe procedure)
Time required for Pipe Section (length and diameter dimensions)
Pressure Drop ^seconds)
Field Test Data:
da te Time a .m.__ p .m.
psig
estimated temperature
Start Test: Initial pressure^
Pressure increase due to hydrastatic head
Stop Test: end pressure Psig
Test shows loss of_ psig in- seconds @ average
pressure of
System: pass/ / fail /_ /
Signature of Inspector ,
Date "
146
-------
REPORTING OF LEAKAGE TEST RESULTS
As a condition of approval in all sewage works projects, the
Indiana State Board of Health has recently requested submittal of test
results on the completed sewer system. Test results shall include
detailed information covering the items outlined herein. It will
tto longer be satisfactory to simply state that the sewer system did
not exceed the 200 gal (757 1) limit and, therefore, conclude the system
passes. Field test data will be required for all sections and
manholes of the sanitary sewer. The project engineer will be: respon-
sible for completion and submittal of the tests conducted for the
entire system.
Review of project specifications shall be made with special
attention to compliance with the procedures outlined herein. The
specifications shall indicate which method will be employed if
several are discussed. In no case shall the contractor be permitted
to change to another test if the original method reveals the system
has failed. The section or sections faiiing to meet established
standards shall be repaired by the contractor and retested according
to the test procedure of the original test. Both sets of test data
must be submitted to the Indiana State Board of Health.
147
-------
APPENDIX D
PATTERNED INTERVIEW INFILTRATION/INFLOW ANALYSIS
(Source: Elson T. Killam Associates)
MUNICIPALITY:
COUNTY:
INTERVIEWEE:
1. General Contacts:
Name: __
Address:
Other Contacts:
a. Maintenance:
Name:
Address:
b. Records of Maintenance;
Name:
Address:
c. Maps;
Name:
Address:
d. Engineer;
Name:
Address:
CLIENT:
PROJECT NO:
DATE:
INTERVIEWER:
Title:
Tel. No:
Title:
Tel. No:
Title:
Tel. No:
Title:
Tel. No:
Title:
Tel. No:
148
-------
e. Health Officer:
Name :
Address:
f. Building Inspector;
Title:
Tel. No:
Name:
Address:
g. Plumbing Inspector;
Name:
Address:
h. Planning Board;
Name:
Address:
i. Potable Water Supplier:
Name:
Address:
j. Chamber of Commerce;
Name:
Address:
2. Municipal Officals:
Name
a. Mayor:_
b. Clerk:
c. City Engineer:,
d. Public Works Dir:.
e. Sewer Supt:
Title:
Tel. No:
Title:
Tel.No;
Title:
Tel No:
Title:
Tel. No:
Title:
Tel. No:
Telephone Number
149
-------
f. Sanitary Treatment Plant
Supt. or Operator:
g. Others:
3.
Maintenance Department and Equipment:
Manpower: Foreman Laborers
Equipment: Rodders_
Other Equipment:
Jecs
Eductors
_0perators_
Trucks
Type of Cleaning Program: Preventive_
Details:
_Emergency_
4. Maintenance Records;
Availability: Yes
No
Period Covered by Records: From_
Ty p e: Card s Map
Remarks:
To
Notes
Other
5. Plans and Maps;
a. Storm Sewers:
Overall Scale
_Reproducible_
Date
Location Where Filed
_Date of Updating_
150
-------
b. Storm Interceptors;
Overall Scale
_Rep r oduc i b 1 e_
Date
Location Where Filed_
c. Storm Laterals;
Overall Scale
_Date of Updating_
_Reproducible_
Date
Location Where Filed_
d. Street Maps;
Overall Scale
_Date of Updating_
_Reproducible_
Location Where Filed_
e. Tax Maps;
Overall Scale
_Date of Updating_
Date
_Reproducible_
Date
Location Where Filed_
f. Sanitary Sewers:
Over Scale
_Date of Updating_
Reproducible
Date
Location Where Filed
_Date of Updating_
g. Sanitary Interceptors;
?
Overall Scale Reproducible_
Date
Location Where Filed_
h. Sanitary Laterals;
Overall Scale:
_Date of Updating_
_Reproducible_
Date
Location Where Filed
_Date of Updating_
6. Standard Sanitary Sewer Specifications Availability:
Yes None Attached
Remarks:
151
-------
7. Plumbing Codes;
Yes No
Copy Attached^
_State Code Adopted_
Revised
Remarks:
8. Services:
a. Inspection Riser:
Type of Material for
Pipe & Pipe Joints:
c. Roof Leaders Allowed:
d. Sump Pump Connections:
e. Foundation Drains:
f. Connection Records:
Started _
Present_
Past
(Date)
Present_
Past
Elimination_
Rema rk s
Present
Past
Elimination_
Remarks
Present_
Past
Eliminations_
Remarks
Available_
Period
Type: Cards_
Notes
Stopped
Date_
Date
(Date)
Date
Date
Date
_Date_
Date
Date
Date
_Date_
Date
Yes
No
To
_Map_
Others
152
-------
9. Types of Pipes in Services;
7o Separate % Seperate
Sanitary Storm
a. Asbestos-
Cement
Combined Type of Joints
b. Cast Iron
c. Plastic
d. Reinforced
Concrete
e. Steel
f. Vitrified
Clay
g. Other
TOTAL
10. Lengths of Sewers in Service (total in Miles):
Miles of Sanitary Seperate Storm Combined
% Total Sanitary % Total Storm
Linear Feet:
Sewer Size Sanitary
JLinear Feet:_
Storm
% Combined
Linear Feet:_
Combined Total
8"
10"
12"
15"
18"
153
-------
Manholes;
Manhole Materials: Brick_
Frame Catalog Numbers
Details Attached? Yes
7= Block
Precast
No
11. Maintenance or Operational Difficulties:
What maintenance or operational difficulties have been experienced
regarding the following (please locate affected areas by mark-up
on appropriate map, and complete the questions listed below):
Records:
a. Local flooding of sewers, basement flooding, or back-up:
Who or what department investigated the problem:
What happened? List circumstances, nature, and extent of pro-
blem: ^ —— ——
Where did problem occur? List location, type of area (resi-
dential, commercial, industrial, etc.):
When did problem occur? List date, duration, frequency of
each occurrence, etc.
154
-------
What type of system was involved? List type of pipe material,
age of pipe, type of joints, etc.:
Why and how did problem occur? State your opinion as to why
and in what manner the problem occurred, or the difficulty
that was encountered:
Supplementary information: Describe the ground conditions,
water conditions, etc., in the area in question:
State what corrective action, if any, was (or should be)
taken to correct the situation:
List any other information you may care to volunteer concern-
ing the operational difficulty encountered:
155
-------
Records:
b. Blockages:
Who or what department investigated the problem:
What happened? List circumstances, nature, and extent of
problem: _ —
Where did problem occur? List location, type of area
(residential, commercial, industrial, etc.):
When did problem occur? List date, duration, frequency of
each occurrence, etc: ——
What type of system was involved? List type of pipe material,
age of pipe, type of joints, etc:
Why and how did problem occur? State your opinion as to why
and in what manner the problem occurred, or the difficulty
that was encountered:
156
-------
Supplementary information: Describe the ground conditions,
water conditions, etc., in the area in question:
State what corrective action, if any, was (or should be)
taken to correct the situation:
List any other information you may care to volunteer concerning
the operational difficuly encountered:
Records:
c. Excessive overflow from combined sewers:
Who or what department investigated the problem:-
What happened? List circumstances, nature, and extent of
problem: ——— ,—
157
-------
Where did problem occur? List location, type of area
(residential, commercial, industrial, etc.):
When did problem occur? List date, duration, frequency of
each occurrence, etc: • —
What type of system was involved? List type of pipe material,
age of pipe, t^pe of joints, etc.:
Why and how did problem occur? State your opinion as to why
and in what manner the problem occurred, or the difficuly
that was encountered:
Supplementary information: Describe the ground conditions,
water conditions, etc., in the area in question:
State what corrective action, if any, was (or should be) taken
to correct the situation: — — — —
158
-------
List any other information you may care to volunteer concern-
ing the operational difficulty encountered:
Records:
d. Bypassing of sanitary sewers:
Who or what department investigated the problem:
What happened? List circumstances, nature, and extent of
problem: —......^.—— _~_ ..^.^ ^..l^
Where, did problem occur? 'List location, type of area,
(residential, commercial, industrial, etc.):
When did problem occur? List date, duration, frequency of
each occurrence, etc:---———-—..... - . -.—. - • •••-< - ... - -^ ™
What type of system was involved? List type of pipe material,
age of pipe, type of joints, etc:
159
-------
Why and how did problem occur? State your opinion as to why
and in what manner the problem occurred, or the difficulty
that was encountered:
Supplementary information: Describe the ground conditions,
water conditions, etc., in the area in question:
State what corrective action, if any, was (or should be)
taken to correct the situation:
List any other information you may care to volunteer concern-
ing the operational difficulty encountered:
Records:
e. Overloaded pumping/lift stations:
Who or what department investigated the problem:
What happened? List circumstances, nature, and extent of
problem:
160
-------
Where did problem occur? List location, type of area
(residential, commercial, industrial, etc.):
When did problem occur? List date, duration, frequency of
each occurrence: —— — —, —
What type of system was involved?
age of pipe, type of joints, etc:
List type of pipe material,
Why and how did problem occur? State your opinion as to why
and in what manner the problem occurred, or the difficulty
that was encountered:
Supplementary information: Describe the ground conditions,
water conditions, etc., in the area in question:
State what corrective action, if any, was (or should be) taken
to correct the situation: ——
161
-------
List any other information you may care to volunteer concerning
the operational difficulty encountered:
Records;
f. Overloaded treatment plant:
Who or what department investigated the problem:
What happened? List circumstances, nature, and extent of
problem: —-— — —— —~~^
Where did problem occur? List location, type of area,
(residential, commercial, industrial, etc.):
When did problem occur? List date, duration, frequency of
each occurrence, etc: — —
What type of system was involved? List type of pipe material,
age of pipe, type of joints, etc:
162
-------
Why and how did problem occur? State you opinion as to why
and in what manner the problem occurred, or the difficulty
that was encountered:
Supplementary information: Describe the ground conditions,
water conditions, etc., in the area in question:
State what corrective action, if any, was (or should be)
taken to correct the situation:
List any other information you may care to volunteer concern-
ing the operational difficulty encountered:
Records:
g. Pavement cave-ins:
Who or what department investigated the problem:
163
-------
What happened? List circumstances, nature, and extent of
problem: ————————-^.^.^^.. ..— -— • - ~*~-
Where did problem occur? List location, type of area
(residential, commercial, industrial, etc.):
When did problem occur? List date, duration, frequency of
each occurrence, etc: • ™ ___„— '-
What type of system was involved? List type of pipe material,
age of pipe, type of joints, etc:
Why and how did problem occur? State your opinion as to why
and inwhat manner the problem occurred, or the difficulty
that was encountered:
164
-------
Supplementary information: Describe the ground conditions,
water conditions, etc., in the area in question:
State what corrective action, if any, was (or should be)
taken to correct the situation:
List any other information you may care to volunteer concern-
ing the operational difficulty encountered:
Records:
h. Sewer clogging with sand/grit:
Who or what department investigated the problem: .-
What happened? List circumstances, nature, and extent of
problem:
165
-------
Where did problem occur? List location, type of area
(residential, commercial, industrial, etc.)!
When did problem occur? List date, duration, frequency of
each occurrence, etc: *
What type of system was involved? List type of pipe material,
age of pipe, type of joints, etc:
Why and how did problem occur? State your opinion as to why
and in what manner the problem occurred, or the difficulty
that was encountered:
Supplementary information: Describe the ground conditions,
water conditions, etc., in the area in question:
State what corrective action, if any was (or should be)
taken to correct the situation:
Ififi
-------
List any other information you may care to volunteer concern-
ing the operational difficulty encountered:
Records:
i. Other troubles:
Who or what department investgated the problem:
What happened? ifist circumstances, nature, and extent of
problem: ——- - --- .. - •—-, — -, . - • - • - ,
Where did problem occur? List location, type of area.,
(residential, commercial, industrial, etc.):
When did problem occur? List date, duration, frequency of
each occurrence, etc: , . ^_^__-
What type of system was involved? List type of pipe material,
age of pipe, type of joints, etc:
167
-------
Why and how did problem occur? State your opinion as to why
and in what manner the problem occurred, or the difficulty
that was encountered:
Supplementary information: Describe ground conditions,
water conditions, etc., in the area in question:
State what corrective action, if any, was (or should be)
taken to correct the situation: :
List any other information you may care to volunteer concern.-
ing the operational difficulty encountered:
12. List of Industries:
Name
Address
Type of
Manufac ture
Di scharge
in GPD
168
-------
13. Water Supply;
Name:
Name of Contact:
-Tel No.
a. Are water consumption data available? Yes_
b. What form
No
c. Can water usage of section of municipality be determined?
Yes No
14.
Supplementary Reports and Data;
a. Master Plan available? Yes_
b. Zoning Map available? Yes
No
No
c. Annual Reports available? Yes_
No
d. Previous infiltration/Inflow Studies available? Yes
No
169
-------
Job No.
APPENDIX E
MANHOLE INSPECTION CHECK LIST
(Source: Elson T. Killam Associates)
Manhole No.
Location.
Municipality.
Date
•Crew-
Cover:
Riser:
Bench:
Main Line
Up Stream:
Side Line
Up Stream:
Manholes:
-Time-
-Weather: Su H F R Sn C
_Solid
.Ventilated
JLock
Bolted
_Precast
_Block
_Brick
_Poor Joints
JLeaking
Frame:
Corbell &
Barrel:
_Poured
"Brick
_0ther
_Poor
_Missing
_Dirty
Channel:
_Size
_Depth of Flow
_Material
_Crooked
_0bstrueted
_Dirty (Explain)
_Size
_Depth of Flow
_Material
_Crooked
_0bstrueted
_Dirty (Explain)
MainLine
Down Stream:
Side Line
Up Stream:
_Height of Surchage above Invert
_Height of Ground Water above Invert
Low
^Shifted
_Crooked
Loose
_Precast
_Block
_Brick
_Poor Joints
_Leaking
_Poured
_Brick
JPipe
_Poor
_Missing
_Dirty (Explain)
_Size
_Depth of Flow
_Material
_Crooked
_0bstuctred
_Dirty (Explain)
_Size
_Depth of Flow
_Material
_Crooked
_0bstrueted
_Dirty (Explain)
170
-------
Steps:
_Broken
_Missing
Worn
Comments:
171
-------
r
APPENDIX F
STANDARDS FOR SELECTED SEWER PIPE AND APPURTENANCES
(Source: American Society of Testing & Materials-ASTM)
Condensed Title
I. Asbestos-Cement Pipe
Asbestos-Cement
Non-Pressure
Sewer Pipe
Designation
C-428
Standard Definitions
of Terms Relating to
Asbestos-Cement and
Related Products
Standard Methods of
Testing Asbestos-
Cement Pipe
C-460
C-500
Linings for Asbestos-
Cement Pipe
C-541
Description
Material Specification--Non-
pressure Sewer Pipe for con-
veying sanitary sewage in
gravity-flow systems. Sizes
8 in. (20.32 cm) through 42 in.
(1.07 m) in seven crush-
strength designations of Class
1500, 2400, 3300, 4000, 5000,
6000, 7000.
Definitions of terms, alpha.-
betically listed used in other
ASTM Specifications on Asbes-
tos-Cement products, including
pipe.
Methods covering the testing
of Asbestos-Cement pipe for
hydrostatic strength, crushing
strength and uncombined cal-
cium hydroxide for use in
connection with the individual
specifications for asbestos-
cement pipe. (Flexural
strength).
Requirements for plastic
linings to be applied to asbes-
tos-cement pipe, designed for
special service in carrying
corrosive fluids and in mini-
mizing interior build-up on
the pipe wall. Includes ad-
hesion and chemical require-
ments, plus dimensional mea-
surement requirements and
method of determination.
172
-------
Asbestos-Cement Non-
Pressure Small Diameter
Sewer Pipe
Rubber Rings for
Asbestos-Cement Pipe
II. Clay Sewer Pipe
Vitrified Clay Pipe,
Extra Strength,
Standard Strength
and Perforated
Testing Vitrified
Clay Pipe
Compression Joints for
Vitrified Clay Pipe and
Fittings
Installing Vitrified
Clay Sewer Pipe
Low Pressure Air Test
of Vitrified Clay Pipe
Sewer Lines 4 to -12 in.
(10.2 to 30.5 cm).
C-644 Material Specification - Non-
Pressure sewer pipe for con-
veying sanitary sewage by gra-
vity flow from point of occu-
pancy to system of disposal.
Sizes 4, 5, and 6 in. 0-0.2, 12,7
and 15.24 cm) three crush-strength
designations of Class 1500,
2400, and 3300.
D-1869 Requirements for rubber rings
used to seal the joints of
asbestos-cement pipes, con-
forming to the various ASTM
pipe Specifications. Covers
chemical and physical require-
ments of both non-oil resis- ,
tant and oil-resisitant rubber
rings and methods of test.
C-700 Provides criteria for accep-
tance, including crushing
strengths, hydrostatic tests,
acid resistance, and dimension
for sizes 3 - 42 in. (7.62 through
107 cm) diameter.
C-301 Describes equipment for, and
methods of, testing clay pipe
for crushing strength, absorp-
tion, hydrostatic capacity and
acid resistance.
C-425 Describes factory testing pro-
cedures and established accept-
ance criteria for clay pipe
joints and jointing materials.
C-12 Describes methods of install-
ation, correlates pipe strength
to bedding practices and re-
commends backfilling practices.
C-828T Describes procedures and
criteria for air testing in-
stalled sewer lines.
173
-------
III. Concrete Pipe
Plain Concrete Non-
Pressure Sewer Pipe
C-14 Non-reinforced pipe sizes 4 to
36 in. (10.2 to 91.44 cm); three
strength classifications.
Reinforced Concrete Non- C-76
Pressure Sewer Pipe
Gasketed Joints for
Circular Concrete
Sewer Pipe
Concrete Manhole
Sections
Standard Methods of
Testing Concrete Pipe
Reinforced Concrete
Arch Pipe
Reinforced Concrete
Elliptical Pipe
Standard Definitions
Reinforced Concrete
D-Load Pipe
Reinforced pipe, sizes 12 in.
(30.5 cm) up; five strength
classifications.
C-443 Gasket requirements, joint
geometry, performance tests,
C-478 Requirements for standard pre-
cast manhole components.
C-497 Test methods referenced in
standard pipe specifications.
C-506 Reinforced pipe, arch shape,
sizes 11 x!8 in. (28 x 46 cm)'
through 106 x 169 in. (269.24 x
429.3 cm) horizontal or
vertical alignment; five
strength classifications, each
mode,
C-507 Reinforced pipe, elliptical
shape, sizes 14 x 23 in. (36 x
58.42 cm) through 115 x 181 in.
(292.1 x 460 cm) horizontal or
vertical alignment; five
strength classifications, each
mode.
C-822 Definitions of terms relating
to concrete pipe and related
products.
C-655 Reinforced pipe, sizes 12 in.
(30.5 cm) up, with provision for
design to meet specified load
conditions.
IV. Plastic Pipe
A. Acrylonitrile-Butadiene-Styrene (ABS)
ABS Composite Pipe
D-2680 8-15 in. (20.32 - 38.1 cm) solvent-
cemented and gasketed joint
174
-------
ABS Sewer Pipe
pipe, including quality con-
trol tests and installations.
D-2751 2-12 in. (5.1 - 30.5 cm) solvent-
cemented and gasketed joint
pipe, including quality con-
trol tests and installations.
ABS Solvent Cement D-2235
B. Polyvinyl Chloride (PVC) Pipe
Type PSP PVC Sewer
Pipe and Fittings
Type PSM PVC Sewer
Pipe and Fittings
Rigid PVC Compounds
and Chlorinated PVC
Compounds
Standard Method of
Test for Quality of
Extruded PVC Pipe by
Acetone Immersion
Solvent Cements for
PVC Plastic Pipe and
Fittings
Quality control for ABS cement.
D-3033 Covers requirements and methods
of test for materials, dimen-
sions, workmanship, flattening
resistance, impact resistance,
pipe stiffness, extrusion qual-
ity* joining systems, and a
form of marking for Type PSP
PVC sewer pipe - 4-15 in. (10.2
38.1 cm) pip.e.
D-3034 Covers requirements and methods
of test for materials, dimen-
sions, workmanship, flattening
resistance, pipe stiffness,
extrusion quality, joining sys-
tems, and a form of marking for
the type PSM PVC sewer pipe -
4-12 in. (10.2 - 30.5 cm) pipe.
D-1784-69 This covers rigid plastic com-
pounds composed of PVC, Chlor-
inated PVC, Vinyl Chloride
copolymers, and the necessary
compounding ingredients.
D-2152-67 This method covers the deter-
mination of the quality of ex-
truded rigid PVC as indicated
by reaction to immersion in
anhydrous acetone.
D-2564-73a Provides general requirements
for PVC solvent cements to be
used in joining PVC pipe and
socket-type fittings.
175
-------
Making Solvent-Cement D-2855-73
Joints with PVC Pipe
and Fittings
Bell End PVC Pipe D-2672-73
A procedure is described for
making joints with PVC pipe,
both plain end and fittings,
and bell ends, by means of
solvent cement.
Covers bell-end PVC pipe
made in standard thermo-
plastic pipe dimension ratio
and schedule 40 sizes; pipe
is pressure rated for water.
C. Standards Applicable to All Plastic Pipe
Standard Recommended
Practice for Under-
ground Installation
of Flexible Thermo-
plastic Pipe
External Loading Pro-
perties of Plastic
Pipe by Parallel-Plate
Loading
Impact Resistance of
Thermoplastic Pipe
and Fittings by Means
of a Tup (Falling
Weight)
Flexible Plastic
Sewer Pipe Joints
D-2321-72 This recommended practice
describes procedures for in-
stalling single-wall thermo-
plastic sewer pipe in exca-
vated trenches. These in-
stallation procedures are pre-
dicated on the assumption that
the pipe will perform in accor-
dance with "flexible conduit"
theories.
D-2412-72 Covers the determination of
load-deflection characteris-
tics, calculation of stiffness
factors, and measurement of the
load and deflection at rupture
of plastic pipe under parallel-
plate loading.
D-2444-70 Covers the determination of
the energy required to produce
failure in thermoplastic pipe
of fittings under specified
conditions of impact by means
of a tup (falling weight).
D-3212 Quality control for gasketed
pipe joints.
Plastic Pipe Dimensions D-2122 Measuring plastic pipe.
Conditioning Plastics
and Electrical Insul-
ating Material for
Testing
D-618-61 These methods define procedures
for conditioning plastics and
electrical insulating material
prior to testing, and the con-
ditions .under which they shall
be tested.
176
-------
Standard Definitions
of Terms Relating to
Plastics
D-883-73a A compilation of definitions and
technical terms used in the
plastics industry, terms that
are generally understood or
adequately defined in other
readily available sources.
V. Corrugated Steel Pipe
(ASTM des-
ignation is
not avail-
able for
corrugated
steel pipe
for sewers)
Federal Specifications cor-
rugated Steel Pipe Class I,
Series A and B describes cir-
cular pipe with annular 3 x
0.5 in. (7.62 x 1.3 cm) and
3 x 1 in. (7.62 x 2.54 cm) cor-
rugations. Coating Types G,
H, and J describe asbestos-
protected, asphalt-coated,
paved or lined respectively.
Use Federal Construction Guide
Specification 02501 Section 14
for tests to qualify joint for
watertight requirements speci-
fied in this document.
177
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-77-017d
3. RECIPIENT'S ACCESSION"NO.
4. TITLE AND SUBTITLE
SEWER SYSTEM EVALUATION, REHABILITATION
AND NEW CONSTRUCTION
A Manual of Practice
5. REPORT DATE
December 1977 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHORtS)
Richard H. Sullivan, Morris M. Cohn, Thomas J. Clark,
William Thompson, and John Zaffle
8. PERFORMING ORGANIZATION REPORT NO.
9, PERFORMING ORGANIZATION NAME AND ADDRESS
American Public Works Association
1313 East 60th Street
Chicago, Illinois 60637
10. PROGRAM ELEMENT NO.
1BC611
11. CONTRACT/GRANT NO.
803151
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory—Gin.,OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
^
EPA/600/14
IS. SUPPLEMENTARY NOTES
Project Officer: Anthony N. Tafuri
(201) 321-6679
8-340-6679
16. ABSTRACT This Manual of Practice has been prepared for use by local authorities and
consulting engineers for the investigation of sewer systems for infiltration/inflow.
This Manual discusses three areas: sewer system evaluation, sewer rehabilitation, and
design of new systems to minimize infiltration/inflow.
Procedures for conducting the System Analysis and Sewer System Evaluation Study
(SSES) are described in detail.
Sewer cleaning equipment and methods of sewer inspection are discussed in detail.
Factors which govern the cost of conducting work are given. Rehabilitation techniques
are described and an analysis of factors to be considered for each method described.
Establishment of infiltration limits for new construction is recommended at a rate
not to exceed 200 gal/in.-diam/mi/day (185.2 1/cm-diam/km/day). Methods of testing
are explained in detail.
This Manual of Practice was submitted in partial fulfillment of Grant No. 803151 by
the American Public Works Association under the sponsorship of the U.S. Environmental
Protection Agency. Companion documents also submitted in fulfillment of this project
are EPA-600/2-77-017a, "Economic Analysis, Root Control, and Backwater Flow Control As
Related to Infiltration/Inflow Control," EPA-600/2-77-017b, " . . . ; Appendices," and
EPA-600/2-77-017c, "Sewer Infiltration and Inflow Control Project and Equipment Guide.1
This Manual covers a period from July, 1974 to August, 1976 and work was completed as
of May, 1977.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Sewers, Cleaning, Fluid
infiltration, Water influx,
Inspection, Flow measurement,
Renovating, Tests, Construction
b.lDENTIFIERS/OPEN ENDED TERMS C. COS AT I Field/Group
Infiltration/inflow control
and detection, Sewer cleaning,
Sewer inspection, Sewer reha-
bilitation, Infiltration/inflow
elimination, Sewer system
analysis, Sewer construction,
Sewer testing
13B
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport/
UNCLASSIFIED
21. NO. OF PAGES
i 192
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
178
4U.S. GOVERNMENT PRINTING OFFICE: 1978— 757-140/6842
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