WATER POLLUTION CONTROL RESEARCH SERIES 11022 EFF 12/70
Control of Infiltration and Inflow
into Sewer Systems
Y
PROTECTION AGENCY • W \TER QUALITY OFFICE
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HATER POLLUTE CONTROL RESEARCH SERIES
The Water Pollution Control Research Reports describe the results and progress
in the control and abatement of pollution of our nation's waters. They provide
a central source of information on the research, development and demonstration
activities of the Water Quality Office of the Environmental Protection Agency,
through in-house research and grants and contracts with the Federal, State,
and local agencies, research institutions, and industrial organizations.
Triplicate tear-out abstract cards are placed inside the back cover to facili-
tate information retrieval. Space is provided on the card for the user's
accession number and for additional key words. The abstracts utilize the
WPS 1C system.
Inquiries pertaining to Water Pollution Control Research Reports should be
directed to the Head, Project Reports System, Planning and Resources Office,
Research and Development, Water Quality Office, Environmental Protection
Agency, Washington, D.C. 20242.
Previously issued reports on the Storm and Combined Sewer Pollution Control
Program:
11034 FKL 07/70 Storm Water Pollution from Urban Land Activity
11022 DMU 07/70 Combined Sewer Regulator Overflow Facilities
11024 EJC 07/70 Selected Urban Storm Water Abstracts, July 1968 -
June 1970
11020 — 08/70 Combined Sewer Overflow Seminar Papers
11022 DMU 08/70 Combined Sewer Regulation and Management - A Manual
of Practice
11023 --- 08/70 Retention Basin Control of Combined Sewer Overflows
11023 FIX 08/70 Conceptual Engineering Report - Kingman Lake Project
11024 EXF 08/70 Combined Sewer Overflow Abatement Alternatives -
Washington, D.C.
11023 FOB 09/70 Chemical Treatment of Combined Sewer Overflows
11024 FKJ 10/70 In-Sewer Fixed Screening of Combined Sewer Overflows
11024 EJC 10/70 Selected Urban Storm Water Abstracts, First Quarterly
Issue
11023 — 12/70 Urban Storm Runoff and Combined Sewer Overflow Pollution
11023 DZF 06/70 Ultrasonic Filtration of Combined Sewer Overflows
11024 EJC 01/71 Selected Urban Runoff Abstracts, Second Quarterly Issue
11020 FAQ 03/71 Dispatching System for Control of Combined Sewer
Losses
11022 EFF 01/71 Prevention and Correction of Excessive Infiltration
and Inflow into Sewer Systems - A Manual of Practice
To be continued on inside back cover
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CONTROL OF INFILTRATION AND INFLOW INTO SEWER SYSTEMS
by the
AMERICAN PUBLIC WORKS ASSOCIATION
for the
ENVIRONMENTAL PROTECTION AGENCY
WATER QUALITY OFFICE
and
THIRTY-NINE LOCAL GOVERNMENTAL JURISDICTIONS
Program No. - 11022EFF
Contract 14-12-550
December, 1970
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.25
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SPONSORING LOCAL AGENCIES
City of Akron, Ohio
City of Albuquerque, New Mexico
City of Ann Arbor, Michigan
Arlington County, Arlington, Virginia
City of Baltimore, Maryland
Metropolitan District Commission, Boston, Massachusetts
City of Charlotte, North Carolina
City of Charlottetown, P.E.I.
City of Chattanooga, Tennessee
The Metropolitan Sanitary District of Greater Chicago, Illinois
City of Columbus, Ohio
City of Day tona Beach, Florida
City of Indianapolis, Indiana
Kansas City, Missouri
City of Ludington, Michigan
City of Miami, Florida
City of Middletown, Ohio
City of Milwaukee, Wisconsin
City of Minneapolis, Minnesota
City of Montreal, Quebec
City of Muncie, Indiana
City of Oshkosh, Wisconsin
City of Pittsburgh, Pennsylvania
Oakland County, Pontiac, Michigan
City of Puyallup, Washington
City of Richmond, Virginia
City of St. Clair Shores, Michigan
Metropolitan St. Louis Sanitary District, St. Louis, Missouri
City of San Carlos, California
City of San Jose, California
San Pablo Sanitary District, San Pablo, California
Santa Clara County Sanitation District No. 4, Campbell, California
City of Seattle, Washington
City of Springfield, Missouri
City of Topeka, Kansas
Municipality of Metropolitan Toronto, Ontario
City of Wichita, Kansas
Metropolitan Corporation of Greater Winnipeg, Manitoba
Also Contributing
City of Detroit, Michigan
EPA Review Notice
This report has been reviewed by the Environmental
Protection Agency and approved for publication.
Approval does not signify that the contents
necessarily reflect the views and policies of the
Environmental Protection Agency.
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ABSTRACT
Two hundred and twelve public jurisdictions in the
United States and Canada were contacted, and
twenty-six communities were visited. Practices of
consulting engineers and state and provincial water
pollution control agencies were also surveyed.
The surveys indicated that infiltration and inflow
are widespread problems.
Reduction of infiltration should be stressed in both
new and old systems. For new sewers a construction
allowance of no more than 200 gallons per day per inch
of diameter per mile of pipe is recommended. Existing
systems must be extensively investigated to determine
the extent and location of infiltration. Reduction of
inflow waters can be accomplished after sources of such
flows have been identified, alternate methods of disposal
identified, and the backing of public and governing
bodies secured.
Twenty recommendations are given indicating the
need for extensive investigation of the extent of the
infiltration/inflow problem before relief sewers are
constructed or wastewater treatment plants built or
enlarged.
The report includes 43 tables, an extensive review of
reports concerning local infiltration studies, and a
bibliography of 135 references.
This report was prepared for the Environmental
Protection Agency in fulfillment of Contract 14-12-550.
The study was also supported by thirty-nine public
agencies. A companion document, "Manual of Practice,
Prevention and Correction of Excessive Infiltration and
Inflow into Sewer Systems," was also prepared.
Key Words: INFILTRATION, INFLOW, INVESTI-
GATION, INSPECTION, SURVEY.
m
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APWA RESEARCH FOUNDATION
Project 69-la
STEERING COMMITTEE
Paul C. Soltow, Jr., Chairman, San Pablo Sanitary District
George E. Burns, Metropolitan Corporation of Greater Winnipeg
Richard L. Castle, Oakland County, Michigan, Department of Public Works
S. J. McLaughlin, The Metropolitan St. Louis Sewer District
Alfred R. Pagan, (ASCE), Bergen County, New Jersey, Engineer's Office
Lloyd Weller, (WPCF), Black & Veatch Consulting Engineers
Richard H. Sullivan, Project Director
Arthur T. Brokaw, Principal Investigator
Dr. Morris M. Cohn, Staff Consultant
ENGINEERING ADVISORY PANEL
Frank Kersnar, Brown and Caldwell
Walter Thorpe, Tolz, King, Duvall, Anderson and Assoc., Inc.
Charles R. Velzy, Charles R. Velzy & Associates
INDUSTRIAL ADVISORY PANEL
L. E. Gottstein, Chairman,
American Pipe Services
Charles M. Aiken, Raymond International, Inc.
James R. Alley, Certain-teed Products Corp.
Joseph P. Ashooh, The Assoc. General Contractors
of America
Donald M. Cline, Pacific Clay Products
Robert Hedges, Rockwell Manufacturing Co.
Quinn L. Hutchinson, P.E., Clow Corp.
Harold Kosova, Video Pipe Grouting, Inc.
Tom Lenahan, Environmental Control Research Center
W. J. Malcom, Cherne Industrial, Inc.
Joseph McKenna, Industrial Material Co.
Charles Prange, Rockwell Manufacturing Co.
John Roberts, Armco Steel Corp.
Harold Rudich, National Power Rodding Corp.
Joseph A. Seta, Joseph A. Seta, Inc.
H. W. Skinner, Press-Seal Gasket Corp.
E. W. Spinzig, Jr., Johns-Manville Sales Corp.
Edward B. Stringham, Penetryn System, Inc.
William M. Turner, Griffin Pipe Products Co.
Joe A. Willett, American Concrete Pipe Assoc.
John A. Zaffle, United States Concrete Pipe Co.
R. D. Bugher
R. H. Ball
Lois V. Borton
Marilyn L. Boyd
Doris Brokaw
APWA Staff*
R. B. Fernandez
John R. Kerstetter
Shirley M. Olinger
Violet Perlman
Ellen M. Filler
Frederick C. Ross
Terry Tierney
George M. Tomsho
Oleta Ward
Mary J.Webb
*Personnel utilized on a full-time or part-time basis on the project.
IV
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CONTENTS
Page
SECTION 1 Findings and Recommendations of the Study 1
SECTION 2 Infiltration and Inflow Problems: An Overview 5
SECTION 3 Contract Provisions and Implementation 11
SECTION 4 The Infiltration Problem: Causes, Effects,
Prevention and Cure 15
SECTION 5 The Inflow Problem 53
SECTION 6 Jurisdictional Experiences 61
SECTION 7 Building Sewers 75
SECTION 8 Economic Factors 89
SECTION 9 Acknowledgements 95
SECTION 10 Glossary of Pertinent Terms 97
SECTION 11 Bibliography -99
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TABLES
Table No. Page No.
1 National Statistical Survey - Jurisdictions Responding 15
2 National Field Investigations - Sewer Pipe Materials and Joints in Service 17
3 Consulting Engineers Survey-Summary of Pipe Materials Specified to Reduce Infiltration 20
4 National Statistical Survey - Sewer Pipe Material in Use 21
5 National Statistical Survey - Sewer Pipe Material Specified 22
6 Consulting Engineers Survey - Jointing Materials 24
7 National Statistical Survey - Sewer Joints in Place 23
8 National Statistical Survey - Sewer Joints Specified 26
9 Consulting Engineers Survey - Sewer Infiltration Design Allowances 28
10 National Statistical Survey - Infiltration Design Allowances 30
11 Consulting Engineers Survey - Infiltration Construction Allowances 31
12 National Statistical Survey - Infiltration Construction Allowances 32
13 State and Provincial Survey - Infiltration Allowances 33
14 National Statistical Survey - Construction Inspections 34
15 National Statistical Survey - Are Sewers Tested for Leakage? 34
16 National Statistical Survey - Infiltration Testing Methods 35
17 National Statistical Survey - Infiltration Testing Methods, Totals by Population Groups 35
18 National Statistical Survey - Percentage of Sewers Reported Below Ground Water Table 37
19 National Statistical Survey - Annual Rainfall and Maximum Months 39
20 National Statistical Survey - Soil Conditions at Sewer Locations 41
21 National Statistical Survey — Opinions of Local Officials on Importance of Infiltration Problem .... 42
22 National Statistical Survey - Reported Sources of Excessive Infiltration 43
23 National Statistical Survey - Future Corrective Action on Infiltration Control 52
24 National Statistical Survey - Is Inflow a Problem? 55
25 Consulting Engineers Survey - Sources of Inflow 55
26 National Statistical Survey - Sources of Inflow 56
27 National Statistical Survey - Are Downspouts Permitted to be Connected? 57
28 National Statistical Survey - Are Basement Drains Permitted to be Connected? 57
29 National Statistical Survey - Sewer-Use Ordinances 59
30 National Statistical Survey - Responsibility for Enforcement of Sewer-Use Ordinances 60
31 Consulting Engineers Survey - Inflow Correction Benefits 60
32 National Field Investigations — Estimated Percentage of Total Infiltration
Attributed to Building Sewers 76
33 Theoretical Computation of Estimate of Relative Amount of Infiltration
From Building Sewerss 76
34 National Field Investigations - Summary of Permitted Pipe Materials and Joints
in Building Sewers 79
35 Consulting Engineers Survey - Pipe Material Specified for Building Sewers 78
36 Consulting Engineers Survey - Joints Specified for Building Sewers 78
37 National Statistical Survey - Building Sewer Pipe and Joint Materials Specified 81
38 Excerpts from Requirements for Building Sewers, Bloomington, Minnesota 82
39 National Field Investigations - Summary of Specifications, Installation and Inspection
Authority Over Building Sewers 83
40 National Statistical Survey - How Building Sewers are Regulated 86
41 National Statistical Survey - Who Inspects Building Sewers? 87
42 National Field Investigations-Cost of Treatment and Pumping of Infiltration and Inflow 92
43 National Statistical Survey - Have Beneficial Results Been Obtained from Corrective Actions? 93
vi
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FIGURES
Figure No. Page No.
1 Vitrified Clay Segmental Block Sewer, Akron, Ohio 16
2 Chemical Weld Joint 24
3 Compression Gasket Joints 25
4 Well-Point System 38
5 Sewer Construction Under Water 38
6 Infiltration at Offset Joint 46
7 Improperly Installed Sewer Connection 47
8 Broken Joint 47
9 Manually Lined Joints 50
10 Installation of Pipe Liner 51
11 Internal Grouting Equipment 52
12 Infiltration and Inflow from Building Sewer Connections 77
vii
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AMERICAN PUBLIC WORKS ASSOCIATION
Ray W. Burgess
Timothy J. O'Leary
Harmer E. Davis
Board of Directors
Myron D. Calkins, President
William W. Pagan, Vice President
Ross L. Clark, Past. President
Frederick R. Rundle Wesley E. Gilbertson
Lt. Gen. Frederick J. Clarke Herbert Goetsch
Donald S. Frady Leo L. Johnson
Robert D. Bugher, Executive Director
Erwin F. Hensch
Lyall A. Pardee
Gilbert M. Schuster
APWA RESEARCH FOUNDATION
Board of Trustees
Samuel S. Baxter, Chairman
W. D. Hurst, Vice Chairman
Fred J. Benson William S. Foster
John F. Collins D. Grant Mickle
James V. Fitzpatrick Milton Offner
Milton Pikarsky
Robert D. Bugher, Secretary-Treasurer
Richard H. Sullivan, General Manager
Mil
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SECTION 1
FINDINGS AND RECOMMENDATIONS OF THE STUDY
What are the causes, effects, and means of
correcting excessive extraneous waters entering public
sewer systems as a result of infiltration and inflow?
These investigations, surveys, and research activities
were designed to provide dependable information on
which to base practical guidelines for eliminating or
minimizing these conditions. The national study
project carried out by the American Public Works
Association on behalf of the Water Quality Office
of the Environmental Protection Agency and 38
participating jurisdictional agencies has demonstrated
the importance of this problem and defined workable
ways for coming to grips with it.
Outlined here are the study's most significant
findings on this problem and its impact on sewer
systems, urban areas, sewage pumping and treatment
facilities, combined sewer overflows, and national
water resources quality. On the basis of these
findings, recommendations for action are offered
local jurisdictions, state and provincial regulatory
agencies, the consulting engineering profession, sewer
construction contractors, and manufacturers and
service companies serving this field.
This report deals with two sources of extraneous
waters which enter the sewer system: infiltration
which is ground water, and inflows which are the
result of pipe connections. A full definition of both
items is given in Section 2.
Findings and recommendations of the study are
as follows:
1. Infiltration of ground water is an important
source of large volumes of waste water flow in
sanitary and combined sewer systems - in ah1 areas in
jurisdictions of all sizes, with all types of sewer pipe
construction and various types of jointing materials,
and regardless of the type of soil formations in which
the sewers are laid. Infiltration may average as much
as 15 percent of the total flows handled by affected
sewer systems; peak infiltration rates may be 30
percent. Under unusual conditions a separate sanitary
sewer system may assume the flow characteristics of a
combined sewer. In spite of the adverse effect of
infiltration, the importance of this problem has not
been universally recognized.
The most important sources of infiltration
include defective sewer pipe, defective joints, and
defective manholes. Inflow waters, as differentiated
from infiltration, have sources in other parts of urban
areas and sewer systems.
Greater recognition of this problem's importance
on the part of sewer system administrators, sewer
designers, pollution control agencies, contractors and
manufacturers, must be achieved before widescale
corrective actions can be considered and
consummated. All sources of infiltration should be
held suspect before great volumes of extraneous
waters can be eliminated or minimized realistically.
2. Infiltration is affected by ground water levels.
A large percentage of public sewers, now representing
a national total length of 2,942 million feet of sewer
pipe of various sizes and a national monetary outlay
of over $50 billion, are laid at depths which expose
them to ground water infiltration during wet or dry
weather conditions. These conditions should
influence construction of watertight sewers.
Construction of sewers must be carried out in dry
trench conditions by means of adequate pumping or
well-point control of water levels. Conduits must be
laid and joints prepared under proper pipe bedding
conditions. Proper backfilling and compaction of
trench material must be practiced as the best
safeguard against adverse ground water conditions in
all affected construction projects.
3. Sewer system officials and designers have
available a wide choice of sewer pipe materials, in
various sizes, strengths and lengths. The national
survey disclosed the diversity of choices of such sewer
pipe types to meet specific preferences and serve
specific purposes.
Sewer pipe should be chosen not only on the
basis of design strength and construction criteria, but
with full recognition of the relationship between
types of sewer pipe and infiltration control.
4. Great improvements have been made in pipe
jointing materials and installation practices. The use
of flexible compression gaskets for forming joints has
increased at a high rate for all types of sewer pipe and
manhole structures. Designers, sewer system
administrators, and contractors reported that this
type of joint has improved sewer-laying practices and
greatly reduced infiltration through joints, the
greatest point of entry of infiltration water into sewer
systems.
No sewer pipe or manhole is better than its
joints. The choice of joints should be made with full
recognition of their importance in infiltration
control, and they should be installed in conformity
with the recommendations of manufacturers. The
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best joint will not be watertight if installed carelessly
or improperly.
5. In spite of the great improvements in pipe and
joint materials and in construction methods, excessive
infiltration construction allowances are specified by
many designers, sewer system officials, and water
pollution control agencies. There is some tendency to
reduce such allowances and require relatively "tight"
sewer construction. Present infiltration allowances
vary widely and are expressed in varying units of
performance; the predominating requirement is
approximately 500 gallons per inch of sewer diameter
per mile of pipe. However, reductions in this
allowance are beginning to appear in design and
construction practice.
The capabilities of modem pipe and joint
materials should be recognized in setting infiltration
allowances; more rigid and lower infiltration
allowances of 200 gallons per day per inch diameter
per mile of sewer should be required wherever
structurally possible and economically feasible.
Designers should adopt rational infiltration criteria
rather than following standards proposed by other
authorities under conditions that can be overcome by
modern methods and materials. Designers must make
a dearer distinction between infiltration allowances
in sewer design and infiltration allowances hi sewer
construction, in planning modern sewers to meet
today's urban growth problems.
6. Infiltration seriously affects the operation of
sewer systems and pumping, treatment, and overflow
regulator facilities. It also adversely affects the urban
environment and the quality of water resources. The
effects include: usurpation of sewer capacities that
should be reserved for present sanitary sewage flows
and future urban growth; need for construction of
relief sewer facilities prior to originally scheduled
dates; surcharging and backflooding of sewers into
public roads and streets and private properties;
by-passing of raw sewage at various points of spill or
diversion into storm sewers or nearby watercourses;
surcharging of pumping stations, with resultant
excessive wear on equipment, higher power costs or
by-passing of flows to adjacent water sources;
surcharging of waste water treatment plants, with
adverse consequences to treatment efficiencies,
diversion of flow from secondary-tertiary treatment
stages, or by-passing of volumes of untreated waste
water into receiving waters; increases in the incidence
and duration of storm water overflows at combined
sewer regulator stations.
The effect of these conditions on urban
sanitation and water pollution should be recognized
when considering correction of infiltration. Any
overall decisions on infiltration control policies
should recognize the inconsistency of large
expenditures for advanced waste water treatment
facilities to handle excessive infiltration flows.
7. Exfiltration from defective sewer pipe, joints
and other adjunctive parts of sewer systems often is a
significant aspect of the operation and maintenance
of sewer systems. Exfiltration can be the cause of
ground water pollution and, like infiltration, can
undermine sewer lines and produce pipe failures and
pavement cave-ins.
Sources of exfiltration should be located
whenever sewage flows hi downstream sections of
sewer systems indicate an unexplained loss of flow
volumes. A policy that such losses of flow are "good
riddance" must be avoided; exfiltration points should
be corrected.
8. The installation of low rate infiltration sewer
lines can be assured by enforcement of rigid
construction infiltration specifications, backed up by
alert and unremitting inspection of construction, and
followed up by effective sewer inspection and testing
procedures prior to acceptance. Sewer inspection and
testing methods have been improved markedly. The
use of closed-circuit television techniques,
photographic methods, smoke test and air test
procedures, and other practices offer sewer officials
and designers the opportunity to "see the unseen"
and locate points of infiltration in new and existing
sewer systems.
The capabilities of new inspection-testing
methods should be recognized and used whenever
applicable. The expense of such methods in many
instances will be outweighed by the benefits derived.
Research should be undertaken to provide practical
correlations between test results such as those
provided by air and exfiltration tests and actual
infiltration rates, to gain compliance with more
restrictive infiltration allowances.
Rigid inspection should be provided on all
construction projects, since prevention of infiltration
is cheaper and more effective than correction after
installation.
9. Methods for the sealing of defective sewer
pipe and joints, by physical and chemical means, are
widely used to correct infiltration conditions in
existing sewer systems. Internal and external
application methods are available. Sewer sections or
joints actually are replaced in cases requiring physical
reconstruction to allay the effects of excessive
infiltration.
The new methods of sealing points of excessive
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infiltration should be known and evaluated before
any decisions are made on major rehabilitation
procedures. Before such work is instituted it will be
necessary to carry out sewer inspection operations by
the modern methods referred to above. Such
surveillance methods should be preceded by
sewer-line cleaning to make meaningful the
investigation of the sources and extent of infiltration.
A step-by-step multi-phase cleaning-inspection-testing
correction program is the only way to assure effective
rehabilitation of existing sewers. Experienced sewer
service organizations are available in all parts of the
country to carry out this type of overall program or
assist in portions of such multi-phased projects.
10. Building sewers play an important role in
infiltration and contribute to the problems caused by
this type of excessive extraneous water. In some cases
the infiltration volumes from building sewers are
equal to, or greater than, the amount of infiltration
resulting from defective pipe and joints in street
sewers. The total length of building sewers in built-up
urban areas may exceed the footage of street sewers
into which they discharge.
Greater attention should be given to requiring
correction of building sewer defects to reduce
infiltration in existing sewer systems. Sewer agency
officials should make surveys of building sewer
conditions as a part of any overall system survey of
infiltration sources.
11. Improved control over installation of new
building -sewers, including effective specifications
covering type of pipe, joints, rigid inspection, and
approval procedures, can reduce infiltration from this
source. Many jurisdictions experience divided
authority and responsibility for installation and
connection of building sewers — with plumbing or
housing officials controlling the section of such
sewers between the building and the property line,
and sewer, public works, or engineering agencies
.maintaining authority over the section between the
property line and the street sewer.
Divided authority over building sewers can void
proper control over this important source of
infiltration. Wherever feasible, a single authority
should be provided, or coordinated actions by
separate agencies should be encouraged. Jurisdictions
should provide for more definitive specifications for
building sewer construction, more complete
inspection of lines before they are backfilled, and
programs of testing to assure watertightness. Street
sewer stubs awaiting building construction and
connections, as well as abandoned building sewer
connections, should be tightly sealed to eliminate
infiltration through open lines.
12. State and provincial water pollution control
agencies recognize infiltration as an important factor
in sewer system and sewage pumping, treatment and
disposal capabilities, and water pollution control.
However these groups frequently maintain less than
adequate control over infiltration rate allowances and
local adherence to such standards of practice. The
pressures of other phases of waste water collection
and treatment, coupled with inadequate staff
personnel, reportedly limit the attention given to
infiltration control.
State and provincial agencies should give greater
attention to infiltration control, because of the effect
these excessive incursions into sewer systems have on
the effective life span of these systems, by-passing of
sewer lines, pumping installations, waste water
treatment processes, and consequent pollution
control in receiving waters.
13. The benefits derived from the elimination of,
and the cost of, excessive infiltration can be deter-
mined by rational mathematical analyses. Findings
can be used to ascertain the costs versus benefits
balance and justification of proposed corrective
procedures.
Jurisdictions, wherever possible, should carry out
definitive analyses of the effects and costs of
infiltration and the costs of corrective measures.
Sound fiscal decisions should be based on overall long
range costs and other factors such as water quality
impairment due to such infiltration.
Federal and state agencies should grant funds for
complete infiltration surveys and necessary corrective
actions, as a way to reduce the size and costs of waste
water handling and treatment facilities to be financed
with participating federal and state funds.
14. The inflow of extraneous waters into sewer
systems can seriously reduce the carrying capacities
of sewers; cause local flooding and inundation of
private property; produce surcharging of sewage
pumping stations and waste water treatment works;
impair treatment efficiencies; induce excessive and
over-long overflows from combined sewer systems,
and create local water pollution conditions.
Officials of sewer agencies should be increasingly
aware of the effects of inflow into sewer systems.
Sewer-use ordinances or other types of codes or
regulations should be invoked and strictly enforced to
relieve the deleterious effects of excessive inflow.
15. The major sources of inflow into public
sewers include: roof leaders, manhole covers, cellar
and foundation drains, and entry and yard drains.
Many such connections exist in contravention of local
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regulations. Others result from failure of jurisdictions
to impose regulations or enforce them when in effect.
In many cases the volumes of inflow waters far
exceed the quantities anticipated when certain inflow
connections were authorized. Removal of inflow
sources may entail a heavy cost to the homeowner
and a great deal of inconvenience.
Where no control over inflows is in effect,
jurisdictions should consider enacting necessary
regulations. Where sewer-use regulations are in effect
they should be firmly enforced. Where inflows are
permitted under present regulations, jurisdictions
should evaluate the effects of these inflows and take
action to discontinue them if this is deemed necessary
to protect the serviceability of sewer systems and
appurtenant waste water facilities. Illicit and
surreptitious inflow connections should be eliminated
by a system of search and surveillance.
Hie success of such corrective actions will
depend on public cooperation plus full participation
and support from elective officials who represent
property owners. Efforts should be launched to
inform and educate the public on the importance of
control of inflow. Public educational aids such as
motion pictures depicting the value of sewers in the
life and progress of urban areas, and the importance
of inflow and infiltration control, should be
developed. These could help win public support for
the normally unpopular task of getting property
owners or local jurisdictions to invest funds for
eliminating inflow connections.
16. The discharge of so-called "clean waters"
from such sources as commercial air conditioning,
industrial process cooling, and other points of
excessive inflow into sanitary and combined sewers
seriously affects these systems and waste water
handling facilities.
Jurisdictions should encourage commercial and
industrial water users to practice on-stream
reclamation and reuse of such "dean waters,"
thereby reducing the hazards of inflows and curtailing
excessive use of public water supplies.
17. Many jurisdictions report that manhole
covers are used to drain flooded areas into sanitary
and combined sewers, thus overloading these systems
to the peak. In other areas, storm water accumulates
over, and flows into, manholes.
Permanent solutions to drainage problems should
be sought. Adequate separate storm water drainage
should be provided. If manholes are located in
vulnerable areas, perforated covers should be replaced
with tight covers to reduce entry of storm water into
sewer lines.
18. Surcharged sanitary sewers often are relieved
by sewer maintenance crews who interconnect these
lines with nearby storm sewers or surface
watercourses, without the full knowledge or consent
of administrators or sewer design agencies. Such a
break in communications between those who plan
and design sewer systems and those who operate
them exists in many jurisdictions. A similar lack of
communication exists between jurisdictions
discharging into multi-community sewer systems and
the agency receiving and treating these flows. In these
instances, the communities served have little
inducement to eliminate infiltration and inflows,
other than the need to prevent local flooding.
Sewer agencies should discourage maintenance
crews from using diversion procedures in emergency
relief of surcharged sewers, until and unless proper
authorization is given and the interconnections
recorded on maps hi the design engineering office.
Communication should be encouraged between
central waste water interception and treatment
agencies and communities served. In many areas
sewer charges are based upon the volume of flow
contributed from one jurisdiction to another,
minimization of these charges may be the most
compelling reason for reduction of infiltration and
inflow.
19. The need for more specific knowledge of soil
and ground water conditions at sewer construction
sites has been stressed by consulting engineering firms
and some sewer system officials. Predesign and
preconstruction borings of soil and location of
ground water tables, frequently are not made a part
of the project record.
Soil and ground water conditions should be made
a matter of record, to protect both the contractor.
and the owner against unexpected construction
conditions. Better design, tighter infiltration control
allowances, and better construction practices will
result. The need for claims and counterclaims for
construction extras and infiltration noncompliances
will be greatly reduced if such preproject information
is obtained.
20. As a part of this study, a Manual of Practice
was prepared on the means of locating and controlling
infiltration and inflow.
Governmental agencies and consulting engineers
are urged to consider utilization of the guidelines
contained hi the Manual of Practice. The information
contained in the manual should encourage die
ultimate development of "Standards of Practice,"
wherever such criteria are feasible and desirable.
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SECTION 2
INFILTRATION AND INFLOW PROBLEMS: AN OVERVIEW
Infiltration of ground water and inflow of
extraneous waters of all types into United States and
Canadian sewer systems are problems of growing
concern. They have an adverse effect on economic
and environmental conditions in local sewers and
contiguous land areas, and on pumping and treatment
facilities; they cause pollution conditions in receiving
waters. Both of these extraneous water entries usurp
sewei and waste water handling capacities.
The significance of these volumes of extraneous
waters which reduce valuable design capacities of
urban sanitary, combined, and storm sewer systems
was highlighted in the 1967 National Survey entitled
"Problems of Combined Sewer Facility
Overflows-1967." That survey was carried out by the
American Public Works Association for the Federal
Water Pollution Control Administration (now the
Federal Water Quality Administration),
The report on that previous research project
contained this finding:
"The survey showed that infiltration, during
both wet and dry periods, often exceeds design
standards and code regulations, usurping
needed combined sewer capacities and
increasing the frequency and duration of
overflows. Reduction in infiltration in existing
sewers by means of repairs and reconstruction,
and in new sewers by means of better materials,
jointing, construction and inspection, offers
opportunities to reduce overflows. It is
recommended that in-depth studies for
alleviating excessive infiltration and relating it
to incidents and durations of overflows be
undertaken."
The effect of infiltration of ground water on
combined sewer system overflows and on water
pollution adds emphasis to something of even greater
importance - usurpation of the capacities of separate
sanitary sewer systems intended to carry all flows to
waste water treatment plant facilities.
The intrusion of extraneous inflow waters into
sewer systems from various known and unknown
sources, over and above the infiltration flows
investigated in the 1967 National Survey, makes it
highly important to evaluate the total problem and
search for workable corrective actions.
The Federal Water Quality Administration and
the American Public Works Association, on behalf of
38 contributing public agencies, entered into a
contractual agreement in 1969 to make a national
"study of causes and control of ground water
infiltration into sewers." This document is a report
on this "second generation" research project. The
basic purpose of the studies was to investigate the
causes, extent, effects, and means of control of the
overall extraneous water problems of infiltration and
inflow in separate sanitary and combined sewer
systems and appurtenant regulator-overflow, pumping
and treatment facilities. The requirements of this
contract and the way the studies were implemented
are described in Section 3 of this report.
Tfte'Tivo/V"
The contract requirements took cognizance of
the two facets of the entry of so-called extraneous
waters into sewer systems: infiltration and inflow.
The contract defined "Infiltration" in terms of what
this report refers to as the "Two IV* in these words:
"For the purposes of this study, infiltration is
defined as the entrance of extraneous flows
into sanitary, storm, and combined sewers. In
this context the investigations and evaluations
will require consideration of extraneous
(surface) flows resulting from roof and yard
drainage, foundation drains, unpolluted cooling
waters and similar flows into the sewers due to
cracked or broken pipe, leaky joints, root
intrusion, poorly constructed house drains,
improper connections to street sewers and
similar sources,"
Regardless of the sources of waters that enter
sewers and affect their ability to provide urban
sanitation and drainage, the net result is the same:
usurpation or reduction of valuable conduit
capacities. The sewer systems so affected cannot
distinguish between ground waters which have
infiltrated lines through defective points of entry, and
those which have flowed into sewers via points of
direct pipe connections. However, no investigation of
such extraneous waters and their effects on sewer
systems can yield meaningful data and practical
guidelines for elimination unless the "Two 1Y% are
identified, delineated, and evaluated.
The establishment of a firm definition of the two
factors of infiltration and inflow became the first
requirement in developing a plan of action for the
research project, as described in Section 3. To guide
the technical investigators who carried out in-depth.
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in-the-field surveys of representative systems, and
provide practical ground rules for local governmental
officials who supplied other statistical survey
information, the following definitions were adopted:
"INFILTRATION" covers the volume of
ground water entering sewers and house
connections from the soil, through defective
joints, broken or cracked pipes, improperly
made connections, manhole walls, etc.
"INFLOW" covers 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" as previously defined.
"INFILTRATION/INFLOW" - This study
recognizes that in the case of existing sewer
systems it is difficult to distinguish between
"infiltration" and "inflow." For this reason,
the term "infiltration/inflow" is used to cover
those flows of extraneous waters where totals
of the two types of entry waters are involved.
One clarification of the scope of this study must
be made. While the terms of the contract refer to
sanitary sewers, combined sewers, and storm sewers, a
basic priority had to be established for the
investigation. The infiltration and inflow problem is,
first and foremost, of major importance in sanitary
sewers because they are not designed to handle such
extraneous waters in excessive amounts. While
infiltration allowances are made in sewer design and
construction practice, and certain inflows may be
authorized, the ultimate "ideal" of watertight sewers
is recognized as the goal of sewer authorities.
In the case of combined sewers, the impact of the
"Two I's" is of relatively lesser significance because
these dual-purpose conduits are designed to handle
drainage and runoff waters similar in nature to
infiltration and inflow waters. Problems do arise
when the volumes of extraneous waters exceed the
handling capacities of sewer lines, overflow facilities,
and other system appurtenances.
In the case of storm sewers, the impacts of
infiltration and inflow are of even less significance
because these conduits are intended to handle the
same kind of waste waters represented by the "Two
I's."
Infiltration thus is the result of soil conditions,
ground water levels, precipitation, interstitial water
entrained in overlying soils, materials and methods of
construction, and the stability of pipe joints, and
manhole and chamber structures and connections.
Infiltration is a physical factor. The elimination or
minimization of such intruded flows involves
administrative and financial decisions, along with
engineering actions in terms of design, construction,
inspection, and corrective procedures.
Inflow is the result of deliberately planned or
expediently devised connections of sources of waste
water into sewer systems. These connections become
the means of disposing of unwanted storm water or
other drainage water and liquid wastes into a
convenient drain conduit. They can include the
deliberate or inadvertent drainage of low areas
through manhole covers. Inflow can be the result of
authorized discharges, where roof, cellar or
foundation drain connections are permitted by local
regulation, or where discharges of certian spent
waters or wastes into public sewers are authorized. In
addition, it can arise from illicit and unknown
connections made by property owners or home
builders for their convenience and without
authorization. The flow from such sources is a result
of operational conditions that may be located and
corrected by regulation and inspection-surveillance
procedures, aimed at enforcing regulations relating to
sewer connections and use.
Despite these differences in sources and
corrective measures, effective control of infiltration
and inflow factors have two common denominators:
(1) A desire on the part of municipal officials to
search out points of entry and take necessary actions
to eliminate them, and (2) the willingness of the
public to participate in these actions, to the extent of
assuming its equitable share of the cost of eliminating
illicit connections from its properties, and approving
municipal expenditure of funds to correct defective
existing sewers and enhance the quality of new
construction.
The problem of solving infiltration and inflow
may be more difficult in intercommunity or regional
sewer systems fostered by today's metropolitan
growth trends. A community that is not involved in
the interception, pumping, and treatment of its
sewage flow, but discharges its wastes into a regional
or district system, may have little incentive to
eliminate sources of extraneous flows unless charges
are based on volume. In some cases treatment charges
to each participating municipality based on rnetered
flows are an effective way to stimulate active interest
by all parties in reducing points of excessive
infiltration and inflow.
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The Infiltration Problem
The definitions of infiltration and inflow indicate
the sources of these extraneous waste waters.
Infiltration effects have been recognized for more
than a half-century but only current developments, in
terms of urban growth and increased concern over
water pollution conditions, have focused attention on
the problem. Sewer construction materials and
methods have been greatly improved by these stimuli.
The important research and development work
carried out by manufacturers of pipe, joint, and
appurtenant sewer system facilities has recently
produced significant technical advances in this field.
The upsurge of federal and state demands for higher
levels of sewage treatment to prevent pollution and
protect the environment makes excessive infiltration
and inflow critical. Corrective actions now are
essential.
Prior to the present stepped-up clean waters
efforts at national and state levels, the effects of
extraneous flows from both sources were of less
importance. In a sanitary engineering sense, the
gradual usurpation of sewer system capacity was of
less significance then because the slow urban growth
of Jhe past precluded sudden demands on design
capacities assigned to future growth in population
and water consumption. Local sewer surcharging and
backflooding were not as frequent as they are today.
When only a portion of the nation's sewage flows was
treated or inadequately treated, environmental
control authorities were less concerned with the
poUutional effects of excessive combined sewer
overflows and by-passing of sewage from separate
sanitary sewers and treatment plants into receiving
waters.
This era of minor seriousness is gone, as
demonstrated by the consummation of this
infiltration-inflow survey contract with federal and
local funds. All levels of government recognize the
importance of the problem outlined in the findings of
the 1967 National Survey. Proof of the changed
attitude towards correction of infiltration conditions
is found in recent FWQA-sponsored research studies
of workable methods for sealing defective sewer pipe
and joints. Still further proof is the upsurge in
measures now being taken by local governments to
survey their sewer system infiltration problems and
institute corrective measures, such as replacement of
defective sewer sections; the encasement of defective
lines; insertion of tight-sewer tubes within defective
lines, and the sealing of leaking sewers by chemical
and physical means. It is proper to characterize this
shift in infiltration thinking as a trend from medium
to maximum concern.
Causes and Sources of Excessive Infiltration
A listing of the major causes of infiltration serves
as an indication of the ways infiltration can be
reduced:
Poor or improperly constructed sewer joints.
Unstable pipe bedding and soil conditions.
Improper methods of backfilling after sewer
construction.
Open or defective new or abandoned stub
connections from building sewers.
Joints damaged by internal pressure in sewers
or improper sewer cleaning or flushing
operations.
Inadequate testing and inspection of sewer
construction.
Improper construction of building sewer
lines and their connections into street sewers
without adequate control and inspection.
Improper construction of manholes and
other sewer system appurtenances.
Pipe deterioration from interior or exterior
sources.
Pipe damage at points where conduits are
laid in varying soil formations, such as where
building sewers cross over from shallow
building sewer trenches to deep street
trenches.
This research and report have taken cognizance
of all of these sources of infiltration, as well as the
obvious sources of inflow. They give detailed
information on local practices and experiences.
Factors Influencing Control of Infiltration
Repeated emphasis is placed here on infiltration
because it is a factor which local governmental action
can correct. Inflow is less amenable to control by
technical action and engineering practices.
The means of controlling infiltration take two
forms: (1) prevention or minimization of infiltration
in all future design and construction work; and (2)
correction of defects in existing sewer systems. The
latter corrections must be based on a survey of
existing systems; the location of points of infiltration;
the determination of the amounts of infiltration
involved and the physical causes, and the correction
of these infiltration defects if cost-versus-benefit
analyses show it to be warranted. Corrective measures
involve "healing" and "sealing" of the points of entry
by means of materials and techniques now available.
-------
Corrections, in some cases, may be effected only by
complete or partial replacement or reconstruction of
defective sewer sections or appurtenant structures.
Minimization of all future infiltration rates will
require the application of engineering principles of
design, the use of effective pipe and joint materials,
proper construction and jointing methods, and the
inspection, testing, and acceptance of sewer lines
which meet rigidly drawn and tightly enforced
standards.
The Inflow Problem
Inflow connections that usurp sewer capacities
pose a challenging demand for better administrative
regulation and enforcement practices.
Crystallization of interest in inflow sources and
their control has not been as strongly evident as it is
in the case of infiltration. While infiltration rate
criteria have been established as an approach to
engineering design standards, the amount of inflow
necessarily has been indeterminate and undetermined.
The physical connections that contribute large
volumes of liquid flows have been less subject to
engineering determination and technological
corrections. This excessive flow increment, to a great
extent, has been influenced by human and political
factors. It is an anomaly that the urban population
and housing explosion, and burgeoning
industrial-commercial growth, may be adversely
affected by inflow into sanitary sewer's from.
residential buildings and business structures. The
service life expectancy of sanitary sewers may be
shortened by flows which normally require no
treatment and which more properly could be diverted
to urban storm drainage lines or recycled for reuse in
industrial and commercial operations.
New local administrative policies may foretell
greater control of inflow conditions. The adoption of
sewer-use regulations or ordinances is being
encouraged by technical organizations, and municipal
acceptance of this important policy is becoming more
prevalent. However, public support is the most vital
ingredient. This embraces willingness on the part of
builders and realty developers to restrict the
introduction of roof, foundation, and basement
drainage into house connections to public sewers;
willingness of property owners to search out and
correct illicit connections, and a desire of property
owners to cooperate with municipal regulations
aimed at eliminating or reducing such inflows. From
their monetary obligations for such corrective action,
property owners will get dividends not always
immediately evident to them, such as reduction of
surcharging of sewers and elimination of local
backflooding into their property and onto adjacent
lands.
Effects of Infiltration and Inflow
Little attention has been given in the past to
determining the amount of infiltration and inflow
carried by existing sewer systems. Part of this lack
must be attributed to an inability to differentiate
between infiltration and inflow when excessive flows
are experienced in existing sewer systems. The
problem has been confused further by the inability to
attribute seriously increased flows in sewer systems,
pumping stations, and treatment plants to the direct
inflow of storm water flows or to infiltration — or to
deliberate or unavoidable interconnections of sewer
lines by the governmental jurisdictions themselves.
Marked increases in separate sanitary sewer flows are
commonly experienced during storm periods. These
conditions have produced the following effects on
sewer networks and appurtenant portions of these
systems.
Flooding of local sections of sewers and
inundation of streets and roads.
Backflooding into private properties.
Increased cost of pumping.
Reduced life of pumping station equipment
(because of excessive operation).
Increased cost of sewage treatment plant
operation.
Reduced life of sewage treatment plant
equipment and devices (because of excessive
loading and longer periods of operation).
Clogging of sewers with sand and soils which
are waterbome by infiltration flows.
Clogging of sewers with root growths which
find their way into conduits via the same
points of entry available to infiltration water.
Reduction in the ability of existing sewers to
accommodate new urban developments.
Need for new sewer construction to replace
the capacities pirated by infiltration and
inflow.
Street and road failures due to undermining
of surface areas by infiltration and sand and
soil intrusion into sewer systems.
Inadequate treatment of sewage flows, due
to overtaxing of process capacities with
infiltration and inflow volumes.
By-passing of flows from separate sanitary
sewers at pumping stations to alleviate
surcharges in pits, pumps, and force mains.
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By-passing of excessive peak flows from
sanitary sewers into storm drains or local
streams to prevent or reduce local back-up
and flooding of streets and private
properties.
Diversion of parts of flows from sewage
treatment plant processes, and inadequate
treatment during excessive periods of
infiltration and inflow.
Spills of excessive amounts of combined
sewer flows at regulator-overflow structures.
The presence of infiltration even during
dry-weather periods indicates the problem that
contributes to combined sewer overflows during
periods of storm runoff.
Exfiltration, the leakage from sewers into the
surrounding soil, can pollute ground water, endanger
the quality of well supplies, and cause subsurface
washouts that can produce instability of sewer
structures and ultimate failure.
Most of these factors have an important and
direct impact on pollution conditions of the receiving
waters. Present efforts to achieve.higher standards of
effluent quality by means of advanced degrees of
treatment, and funds dedicated to maintaining more
rigid quality standards in public waters, will be
thwarted or rendered financially unsound if
infiltration and inflows are permitted to rob sewers of
carrying capacities and treatment plants of their
process performance capabilities.
The Ideal Sewer System
Correction of the most important sources of
infiltration is physically possible and, in many cases,
economically feasible. Modern day methods of
underground surveys can locate sewer system defects.
In a majority of cases, sewer stability can be restored
without excavating pavement and interfering with the
flow of urban traffic and the public convenience.
Again, in this phase of corrective action, new sealant
techniques now are available and are being improved
by chemical formulations and application methods.
New sewer construction also can meet the criteria
of practical idealism. Improved types of sewer pipe
are available, and new jointing practices can assure
watertight construction and almost complete freedom
from infiltration without sacrificing the desired
flexibility of sewer conduits. Better methods of
trench preparation and sewer laying can assure
construction under dry conditions that will provide
proper alignment of sewer pipes, full soil support, and
clean joints. New methods of testing for sewer leaks
can be used to guarantee compliance with more rigid
infiltration limits. The trend in infiltration allowances
is on the "down" side. Former specification
allowances of 500 gallons per mile per inch of
diameter of pipe, or more, have been revised to 200
or 100 gallons or less. The engineering profession is
beginning to recognize that bottletight sewers are not
an idealistic impossibility.
The "ideal" sewer system, in brief, is one which
minimizes infiltration and limits inflow points to
prevent usurpation of capacities; is free from
stoppages due to root growth; has effective
self-scouring capacities, and delivers to pumping and
sewage treatment facilities the flows that need
purification in order to prevent pollution of receiving
waters.
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SECTION 3
CONTRACT PROVISIONS AND IMPLEMENTATION
The goal of this research study was to produce
reliable information on the causes, extent, and
control of storm and ground water infiltration into
sanitary and combined sewers - data that would be
useful to designers and contractors, and to planning,
operating, maintenance and inspection forces of
urban-area public agencies having responsibilities for
sanitary and combined sewers.
Contract Provisions
The contract covering this project stipulated:
"The contractor shall investigate and determine the
current state of the art relating to the technical,
economic and social aspects of infiltration of
extraneous waters into sanitary, storm, or combined
sewers. The extent, causes and corrective measures
relating to infiltration shall be reported and evaluated
with specific needs for research and development
efforts identified."
To clarify the two types of extraneous water
flows covered by the research project, the staff
developed specific terminology for distinguishing one
from the other. The clarification of these basic terms
is outlined in Section 2 of this report. Infiltration
refers to the classic concept of extraneous water
entering the sewer system through broken pipes,
faulty joints, or other defects in the system. Inflow
consists of other extraneous waters connected
directly by pipes or drains to the sanitary sewer or
combined sewer system from such sources as those
enumerated in the contract document. The concept
of inflow* also embraces storm waters entering sewer
lines through manhole covers. Infiltration is a
measure of the physical condition of the system while
inflow reflects the extent of use or misuse of the
system in permitting, legally or illegally, the actual
connection of pipes carrying surface, ground, roof,
and in-structure discharges.
Project Staff Organization
To conduct the survey effectively and utilize
valid national information to produce the required
report and manual, the following staff personnel and
advisory groups were appointed:
• A project director was selected from the
permanent American Public Works
Association staff in Chicago to assume
overall responsibility for planning the
program of action and for direction and
major decisions as the project progressed.
A principal investigator was designated and a
regional field office was set up at Yardley,
Pennsylvania, where most of the project
operations and data collection were centered.
He was a full time APWA Research
Foundation employee, exclusively assigned
to this project.
A staff consultant, with broad experience in
sanitary engineering and municipal sewer
system practices, and in the preparation and
editing of research reports, was designated to
participate in all phases of the project.
An Advisory Committee was formed,
representing all municipal jurisdictions that
were supporting the project by direct
contribution of funds. Each participating
jurisdiction assigned a member of their
agency to the Advisory Committee. The
committee was apprised of all pertinent
study plans and kept informed of the
progress of the project through monthly
reports. The members were called upon to
provide specific project-survey data based on
their professional experience and intimate
knowledge of all facets of infiltration and
inflow problems.
A Steering Committee of six members was
created. Four of these members were
selected from the Advisory Committee while
the American Society of Civil Engineers and
the Water Pollution Control Federation each
were invited to designate one member. The
Steering Committee met at various intervals
during the planning and performance of the
project to review investigative programs and
evaluate study findings, and guide the staff in
interpreting survey data.
A Consulting Engineers' Panel was selected
to work with the staff. Three firms, one each
from the east, west, and central areas of the
United States, were chosen to provide
technical advice on the planning and
execution of the project; participate in the
interviews needed for the national
in-the-field investigation of representative
jurisdictions, and prepare technical material
for the report and manual.
An Industrial Advisory Panel was created, on
the basis of volunteer action, to represent
manufacturers, contractors, and sewer service
11
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organizations in the fields involved in sewer
infiltration problems and their correction.
The panel chose to assign its work to three
subcommittees which devoted specific
attention to sewer pipe and joint materials;
sewer construction practices, and sewer
maintenance, infiltration surveys and
corrective actions.
A small group of engineering investigators
was selected to supplement the staff and
consulting engineers panel in conducting
in-the-field studies and evaluations of sewer
infiltration problems and practices in the 26
representative jurisdictions chosen for the
national investigation. These investigators
were selected for their experience in the field
and their intimate knowledge of sewer
construction and operating procedures in
specific areas of the United States and
Canada.
Special consultants and staff assistants were
selected to provide additional technical data
in the following categories: (1) Literature
search in the general field of sewer
infiltration and inflow; (2) economic
evaluation of the effects and correction of
infiltration and inflow; (3) soil mechanics
and hydrology, as they relate to infiltration
control; (4) review of ordinances relating to
sewer use and waste water discharge into
sewer systems, and (5) collation of survey
data to expedite their interpretation and
evaluation.
Implementation of Contract
The contract stipulated that the project would be
conducted in three phases, as follows:
Phase I - Literature Search
A literature search was instituted to provide
technical reference material of value to officials of
jurisdictions, consulting engineers, and regulatory
agencies, as well as assist the project staff. A
bibliography of selected articles, reports and other
manuscripts pertaining to infiltration and inflow of
extraneous waters was prepared. A staff assistant
collated technical data from the libraries of the Joint
Engineering Societies, New York City; Columbia
University; Princeton University, and many other
colleges and institutions. The editorial offices of
technical magazines and official organization journal
offices were visited for a review of their files. In
addition to a list of pertinent literature in this field,
copies of important reference material were obtained
for staff use. Although a large number of references
were researched, many were repetitious and others
were deemed to have only secondary or tertiary
significance to the project problems. It became
evident that despite the importance of the
infiltration-inflow problem, there was no great wealth
of technical material on many important facets of the
subject. The most pertinent literature references
usually related to specific case histories and system
crises. The finalized version of the bibliography is
contained in Section 11 of this report.
Phase II — Detailed Goals
Phase II, as delineated in the contract, listed 15
specific areas for investigation and interpretation. To
produce the data required, the following surveys and
investigations were initiated:
(1) State and Provincial Water Pollution
Control Regulatory Agency Survey
Fifty states and eight Canadian provinces were
surveyed to ascertain their practices and policies
relating to infiltration and inflow control. The
response to this inquiry was 100 percent in both
nations. The specific purposes for the survey were to:
Determine state regulatory practices.
Ascertain state activity in setting infiltration
design factors.
Determine the opinion of state officials on
the extent and importance of infiltration.
Obtain a supplemental list of jurisdictions
which, in the opinion of the regulatory
agencies, had significant infiltration problems
or had solved such problems by unusually
effective practices.
(2) Field Investigation of Infiltration and Inflow
Problems
Twenty-six local jurisdictions in the United
States and Canada were selected for in-depth
in-the-field investigations of infiltration and inflow
problems and solutions. The choice of these
jurisdictions was based on information obtained from
previous research projects on sewer system and water
pollution conditions. The investigations were
designed to provide definitive information on sewer
system design, construction, operation and
maintenance practices, and on corrections of
infiltration and inflow problems. Representative
information rather than statistical data was sought.
The findings, as reported by trained professional
evaluators, have been the basis of a great deal of the
12
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information contained in the body of this report. The
major purposes of these specific investigations were
to:
Delineate causes of infiltration and inflow
conditions.
Determine the effects of infiltration and
inflow on the entire sewer system.
Disclose design and construction standards
used by these jurisdictions.
Ascertain the testing and inspection methods
used in sewer construction and maintenance.
Explore local policies relating to sewer
system materials and methods.
Determine the methods used for detecting
and correcting infiltration and inflow.
Explore economic evaluations, methods, and
cost data relating to infiltration effects and
corrective measures.
Determine methods for controlling sewer
inflow through sewer-use regulations.
(3) National Statistical Survey
A survey was conducted on infiltration and
inflow conditions in municipalities and jurisdictions
throughout the United States and Canada, selected on
a scheduled statistical basis. Jurisdictions initially
were selected for each state and province on the
following basis:
All cities above 200,000 population.
• Half the cities of 100,000 to 199,999.
• One-fifth of all cities of 20,000 to 99,999.
• Two or three cities of 10,000 to 19,999.
• One city below 10,000.
When the survey data were received, they were
collated and interpreted on a regional basis, as
follows:
East: Connecticut, Delaware, Indiana, Kentucky,
Maine, Maryland, Massachusetts, Michigan, New
Hampshire, New Jersey, New York, Ohio,
Pennsylvania, Rhode Island, Vermont, Virginia, West
Virginia, District of Columbia
South: Alabama, Arkansas, Florida, Georgia,
Louisiana, Mississippi, North Carolina, South
Carolina, Tennessee.
Midwest: Illinois, Iowa, Kansas, Minnesota, Missouri,
Nebraska, North Dakota, South Dakota, Wisconsin.
Southwest: Arizona, New Mexico, Oklahoma, Texas.
West: Alaska, California, Colorado, Hawaii, Idaho,
Montana, Nevada, Oregon, Utah, Washington,
Wyoming.
The inquiry to Canadian jurisdictions was made and
evaluated on the basis of population only.
Because of the statistical manner in which the
surveyed jurisdictions were selected, the authors of
this report assume that the data which the project
developed are representative of overall practices and
conditions. The evaluation and interpretative
discussion of various phases of the national survey, as
contained in sections of this report, are based on this
assumption.
Table 1, National Statistical Survey — Juris-
dictions Responding, indicates the size range and
geographical distribution of jurisdictions responding.
The general purposes of the survey were:
To determine the nationwide extent of
infiltration problems on a statistical basis.
To delineate the causes of infiltration.
To determine the effects of infiltartion and
inflow on sewer systems, pumping stations,
sewage treatment works, combined sewer
regulator-overflow facilities, and other
appurtenant system facilities.
To ascertain the design and construction
standards and requirements.
To evaluate the testing and inspection
methods used in sewer construction and
maintenance.
To determine local practices and standards
covering sewer system pipe nformation and
joint materials.
To determine the methods used for
infiltration and inflow correction and
control.
To gather economic data on the effects and
cost of infiltration correction.
To determine methods used to control
inflow and regulate sewer-use
(4) Consulting Engineering Survey
The project surveyed practices of national
consulting engineering firms to obtain cross-sectional
information covering their knowledge and experience
in sewer system design, construction and maintenance
as it related to control of infiltration and inflow. One
hundred and seventy consulting engineering firms
were contacted; 66 supplied information. The main
purposes of this survey were to:
Determine design factors for infiltration.
Obtain information on typical design
specifications and construction practices.
Evaluate professional opinions on
performance characteristics of sewer-system
materials.
Evaluate opinions on sources and effects of
infiltration.
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TABLE 1
NATIONAL STATISTICAL SURVEY-JURISDICTIONS RESPONDING
Population
200,000
100,000- 20.000-
199,999 99,999
Totals
A. United States
East
South
Midwest
Southwest
West
Subtotal
No. in U. S.
% of U.S. Cities
Rep. in Survey
B. Canada
Total
9
8
4
7
_7_
35
61
57
4
39
7
6
6
2
_8_
29
69
42
2
31
23
10
16
10
30
89
750
12
10
99
5
4
7
4
11
31
1.041
3
3
34
1
0
2
2
_3_
8
16,434
2
10
45
28
35
25
59
192
21
213
Collect information on methods of
infiltration detection and correction.
Determine the experiences of consultants in
eliminating illegal sewer connections and
other sources of inflow.
(5) Building Sewer Connection Survey
A special survey was carried out to determine
infiltration-inflow control policies and building
sewer-connection experience in the jurisdictions that
participated in the project financing.
To achieve this purpose, opinions were solicited
from system officials who were members of the
project Advisory Committee.
Phase III - Report and Manual
As stated in the contract, the principal objecti'
of Phase III of the project was the preparation of
"Manual of Recommended Practice" and a report c
the findings of the study. The Manual, published as
separate document, covers the three general are
enumerated in Phase II, namely:
(1) Design and Construction
(2) Maintenance
(3) Regulatory Practices
The subsequent sections of this report constitu
a record of the findings and evaluation of the surve;
and investigations carried out as parts of this projec
They formed the basis for the findings ar
recommendations presented in this report.
14
-------
SECTION 4
THE INFILTRATION PROBLEM:
CAUSES, EFFECTS, PREVENTION AND CURE
Excessive infiltration is a serious problem in the
design, construction, operation, and maintenance of
sewer systems. Neither combined sewers nor separate
sanitary sewers are designed to accept large quantities
of such infiltration flows.
The problem of infiltration involves two basic
areas of concern: (1) Prevention in new sewers by
adequate design, construction, inspection, and testing
practices, and (2) the elimination or cure of existing
infiltration in old sewers by proper survey,
investigation, and corrective measures.
Control of infiltration in new sewer systems
involves engineering decisions and specification of the
methods and materials of sewer construction; pipe,
joints, and laying procedures and techniques.
Specifications must be prepared with an awareness of
the nature of service required of sewer lines, including
the presence of any deleterious sewage or waste flows
whigh could diminish the integrity or life of the sewer
structure after it has been placed in service.
Control of sewer infiltration in new construction
becomes a challenge to provide sewers that can do the
job, and then protect them against any damaging
conditions, by means of sewer-use ordinances or
regulations. Specifications must provide for trench
and soil control that will assure a firm and safe
foundation for sewer lines. They must recognize that
variable stability of soils on an integral section of
sewer can impose stresses and strains that will make
the best-built lines with the highest quality pipe and
joints subject to shifting and breakage or the opening
of joints.
Effective control of infiltration, therefore,
depends on a two-yronged approach to the problem:
1. Prevention of infiltration is an
engineering-construction problem. The methods
involve proper predesign investigation and
consideration of soil conditions, ground water levels
and seasonal variations, anticipated wastewater flows,
capacities of existing sewers, pumping stations and
treatment facilities, and all other factors which may
influence infiltration rates and the effects of such
extraneous waters on the serviceability and
operability of the entire system. Weighing these
factors, decision is then to be made on choice of pipe
and joints, methods of construction, and on
inspection, testing and acceptance practices.
2. Cure of infiltration involves doing something
about the sewer pipe already in the ground and in
service. Elimination or minimization of infiltration
must be based on survey and investigation of existing
sewers and appurtenant structures in order to locate
sources of infiltration; determination of the extent of
infiltration and the need for correction or sealing of
leaks; choice of methods to be used, and proper
application of the curative method chosen.
The types of pipe and joints used in sewer
construction have an important bearing on the
prevention and cure of infiltration. The effectiveness
of installation and the conditions under which they
function can have an equally great influence on the
tightness of ultimate sewer structures and their ability
to resist excessive ground water entry while in service.
Figure 1, Vitrified Clay Segmental Block Sewer, is a
photograph of a large sewer installed in Akron Ohio
in 1930. Here, as in brick sewers, the extreme amount
of mortar joints often has lead to high infiltration
rates.
Types of Sewer Pipe to Prevent Infiltration in
New Construction
Improvements in pipe material assure the
designer's ability to provide proper materials to meet
any rational infiltration allowances he wishes to
specify. The upgrading of pipe manufacture to meet
rigid quality standards and specifications has
eliminated the basic question of watertightness of
pipe material. However, there may be problems of
structural rigidity and strength of waste water
character, or of local soil or gradient conditions that
would make one material better suited than
another - or preferable under certain special
installation conditions. In such cases or situations,
pipe materials are chosen for reasons other than their
relative resistance to infiltration. During the conduct
of the project surveys it was found that many
consulting engineers and municipal engineers base
their choice of sewer pipe on such special
considerations.
In sections of the country where low ground
water levels and light precipitation prevail, infiltration
itself is not a problem and therefore is seldom
considered in setting sewer design standards.
Nevertheless, a pipe that fails because of inadequate
strength or resistance to subsurface pressures will
crack and thereby permit infiltration or exfiltration,
15
-------
FIGURE 1
Courlerty: United States Concrete Pipe Co.
VITRIFIED CLAY SEGMENTAL BLOCK SEWER
AKRON, OHIO (1937)
depending on the locution of" the sewer in relation to
ground water. A pipe conduit system that is
structurally sound when constructed and retains its
soundness in service will be less prone to abnormal
infiltration. However, in today's practice the material
or element of the sewer system that most influences
infiltration rates is (he joint rather than the pipe
itself.
Cli>>itT "./ Sewer Pipe
During the course
of the study many
representative jurisdictions and consulting engineering
firms were asked to list the types of sewer pipes
which they specrfy. wwth particular emphasis on
control of infiltration.
A large number of engineers reported that almost
all pipe materials and modern joints are capable of
producing infiltration-free sewers. In many instances.
therefore, the design engineers indicated lhat the
sewer pipe materials were selected on the basis of
strength or corrosion resistance characteristics rather
than for infiltration control.
16
-------
TABLE 2
NATIONAL FIELD INVESTIGATIONS SEWER PIPE MATERIALS
AND JOINTS IN SERVICE
Agency
Baltimore, Md.
Bloomington, Minn.
Pipe in Service
Cast Iron
Concrete (Monolithic)
Reinforced Concrete
Vitrified Clay
Cast Iron
Reinforced Concrete
Vitrified Clay
Plastic (Truss)
Other
%of
Total
System
5%
15%
5%
75%
3%
15%
80%
1%
1%
Typical
Joints in Service
(1)
Mortar, "O" Ring, Mechanical
No Joints
Mortar, "O" Ring
Cement, "O" Ring
"O" Ring
Mortar, "O" Ring
Asphaltic, "O" Ring
Chemical Weld
Dallas,Texas
Asbestos Cement
Brick
Cast Iron
Concrete
Reinforced Concrete
Truss
Vitrified Clay
Bit. Coated Corr. Metal
0.82%
0.82%
0.82%
37.40%
3.70%
0.82%
55.54%
0.08%
"O" Ring
Mortar
Lead
Mortar, Plastic
Mortar, Plastic
Chemical Weld
"O" Ring
Denver, Colorado
District of
Columbia, Wash.
Ft. Lauderdale,
Florida
Hot Springs, Ark
Indianapolis, Ind.
Cast Iron
Concrete
Vitrified Clay
Reinforced Concrete
Reinforced Concrete-
Vitrified Clay
Cast Iron
Concrete
Vitrified Clay
Concrete
Vitrified Clay
Cast Iron
Cast Iron
Concrete
Reinforced Concrete
Vitrified Clay
Mechanical
Asphalt, "O" Ring, Mortar
Poured, Mortar, ASTM 425
Asphalt, "O" Ring, Mortar
10% "O" Ring
90% "O" Ring, Bituminous
5% Gasket, Poured Lead
7% Mortar
88% GK, ASTM C-425
40% Mortar, "O" Ring, Hot Asphalt
60% Mortar, Hot Pour, ASTM C-425
<1% Lead, "O" Ring
- Mechanical "O" Ring
— Mortar
"Tylox", "O" Ring
ASTM C-425, Unilock,
Amvit, Wedgelock
(1)
Description is that given by respondents. Thus, both cement and mortar were given. Several names for compression
gaskets such as "O" Ring, Plastic, ASTM C-425, Unilock, Amvit, Wedgelock, Tylox, Neoprene, and Plastisol were given.
17
-------
TABLE 2 (Continued)
Agency
Richmond, Va.
San Jose, Calif.
Savannah, Ga.
Pipe in Service
Concrete
Reinforced Concrete
Vitrified Clay
Brick
Asbestos Cement
Concrete
Reinforced Concrete
Vitrified Clay
Asbestos Cement
Concrete
Reinforced Concrete
Vitrified Clay
Truss
Total
System
.5%
.5%
10%
89%
Typical
Joints in Service
Mortar, "O" Ring
Mortar, "O" Ring
"O" Ring
"O" Ring
"O" Ring
Mortar, "Plastisol"
"O" Ring
Mortar, "O" Ring
"O" Ring, Mortar
Mortar, ASTM C-425
Chemical Weld
Suburban Sanitary
Comm.. Washington,
Toronto, Canada
Watsonville, Calif.
Winnipeg, Canada
Yakima, Washington
Asbestos Cement
Concrete
Reinforced Concrete
Vitrified Clay
Asbestos Cement
Reinforced Concrete
Vitrified Clay
Concrete
Reinforced Concrete
Vitrified Clay
Asbestos Cement
Cast Iron
Concrete
Reinforced Concrete
Steel
Brick
Asbestos Cement
Cast Iron
Concrete
Reinforced Concrete
Vitrified Clay
0.10%
77.9%
1%
5%
85%
5%
10%
85%
15%
5%
37.5%
37.5%
5%
.5%
.5%
74%
15%
10%
"O" Ring
Mortar, "O" Ring
Mortar, "O" Ring
"O" Ring, Mortar
Mortar
Steel Sleeve, "O" Ring
Plastisol
"O" Ring
Mechanical
Mortar, Neoprene Gasket
Mortar, Neoprene Gasket
Welded River Crossing
Mortar
"O" Ring
Lead
Mortar, "O" Ring
"O" Ring
Mortar, Asphalt, "O" Ring
(2)
Agency owns and operates
trunk sewers only
18
-------
TABLE 2 (Continued)
Agency
Pipe in Service
Total
System
Typical
Joints in Service
Jacksonville, Fla.
Asbestos Cement
Cast Iron
Reinforced Concrete
Vitrified Clay
Truss
1% "0" Ring
2% Mechanical, "0" Ring, Poured
26% "0" Ring, Epoxy/Asbestos
70% GK, ASTM 425
1% Chemcial Weld
Janesville, Wise.
Knoxville, Tenn.
New Orleans, La.
Princeton, N.J.
Milwaukee, Wise.
Nassau County, N.Y.
Oakland County,
Michigan
Omaha, Nebraska
New Providence, N. J.
Cast Iron
Concrete
Plastic (Truss)
Reinforced Concrete
Vitrified Clay
Concrete
Reinforced Concrete
Vitrified Clay
Asbestos Cement
Cast Iron
Concrete
Plastic
Vitrified Clay
Asbestos Cement
Vitrified Clay
Concrete
Vitrified Clay
Asbestos Cement
Reinforced Concrete
Asbestos Cement
Cast Iron
Concrete
Plastic
Reinforced Concrete
Steel
Vitrified Clay
Cast Iron
Concrete (Plain & Rein.
Plastic
Steel
Vitrified Clay
Asbestos Cement
Cast Iron
Vitrified Clay
<1% Lead, Mechanical
25% "O" Ring, Mortar
<1% Mortar, Weld
25% "O" Ring, Mortar
50% Hot Asphalt, Amvit
— Mortar, "O" Ring
- Mortar, "O" Ring
Mortar, ASTM C-425
"O" Ring
— Lead, Gasket
— Mortar
- Chemical Weld
Poured, ASTM C-425
25% "O" Ring
75% "O" Ring, Bituminous, Mortar
80% Mortar, Asphalt, PVC, "O" Ring
20% Mortar, Asphalt, Neoprene
7% "O" Ring
93% "0" Ring
<1% "O" Ring
<1% Hot Poured, Mechanical
36% "O" Ring, Asphaltic
<1% Chemical Weld
22% "O" Ring, Asphaltic
<1% Mechanical
42% ASTM C-425
<1% Lead, Mechanical
27% Mortar, Asphaltic
<1% Chemical Weld
<1% Welded, Mechanical
73% Mortar, Asphalt, Prefab.
80% "O" Ring
1% Lead
19% "O" Ring, Mortar
19
-------
Table 2, National Field Investigations - Sewer
Pipe Materials and Joints in Service, presents data on
the various types of pipes in service in the 26
representative jurisdictions investigated.
In the field investigation of 26 representative
jurisdictions, all indicated that they used some
vitrified clay and concrete pipe in sewer construction.
Vitrified clay generally is used in sizes up to 24 inches
in diameter; reinforced concrete is more often
specified for 24-inch pipe and larger. Twelve of the
jurisdictions reported the use of asbestos-cement
pipe; in one case, this pipe constituted 95 percent of
the collection system in the small sizes. Eight
jurisdictions had tried plastic pipe to a limited extent.
Cast iron was used for special construction purposes,
such as stream crossings and areas close to wells, and
when extreme structural strength was required.
Sixty-six consulting engineering firms throughout
the United States and Canada provided information
on the types of pipe materials they specify in their
practices. Table 3, Consulting Engineers
Survey — Summary of Pipe Materials Specified, lists
the data obtained in this survey. In sizes under 18
inches, asbestos-cement and vitrified clay are very
close to equal in frequency of designer specification.
Twenty firms reported that vitrified clay was most
frequently chosen, and 17 firms listed
asbestos-cement as the most frequently chosen. The
frequent use of cast iron pipe, the third most often
cited material, indicated the number of problem areas
requiring extra-strength materials.
Consultants were asked to stipulate the type of
pipe specified in "second-frequency" position in their
design practices. Use of vitrified clay as a second
choice was reported by 17 firms, cast iron by 15, and
asbestos-cement by 14.
The responses to a similar inquiry from more
than 200 jurisdictions throughout the United States
and Canada revealed a similar proportion using
various pipe materials. The results are shown in Table
4, National Statistical Survey — Sewer Pipe Material
In Use, and are classified in terms of sections of the
United States and Canada and population sizes of the
respondent jurisdictions.
The responses indicated that for sanitary sewers
vitrified clay pipe has been used by 166 jurisdictions
in 212 existing systems; concrete pipe by 94
jurisdictions; reinforced concrete in 91; cast iron in
81, and asbestos cement in 42. This trend was
consistent in all regions, but jurisdictions in the
Southwest, South, and Midwest reported very little
past use of asbestos-cement while the East and West
indicated greater use of asbestos-cement.
17
13
4
6
2
1
20
B.
7
8
6
1
32
2
6
14
15
5
2
6
1
17
Over
8
10
3
1
14
2
13
6
5
5
8
12
1
13
18"
6
7
3
2
3
3
8
3
4
9
2
7
6
6
1
1
4
3
8
6
4
2
1
5
4
2
3
1
2
4
4
1
3
2
in Diameter
1
2
3
3
7
2
1
1
1
1
2
4
2
2
3
3
1
2
1
3
4
1
TABLE 3
CONSULTING ENGINEERS SURVEY
SUMMARY OF PIPE MATERIALS SPECIFIED
TO REDUCE INFILTRATION
Number of Firms Reporting by Type of Pipe Specified
A. Under 18" in Diameter
Pipe Material Order of Choice
1 2 34567
Asbestos Cement
Cast Iron
Concrete
Plastic
Reinforced Concrete
Steel
Vitrified Clay
Asbestos Cement
Cast Iron
Concrete
Plastic
Reinforced Concrete
Steel
Vitrified Clay
The same jurisdictions were asked to report the
pipe materials now being specified, in the hope of
determining any clear-cut changes in design practices.
Table 5, National Statistical Survey—Sewer Pipe
Material Specified, summarizes replies.
The total findings for sanitary sewers paralleled
those reported in Table 4: Vitrified clay was reported
as currently used in 154 jurisdictions; reinforced
concrete in 97; cast iron in 71; concrete in 62, and
asbestos-cement in 47. Thus there was a slight
increase in the percentage specifying asbestos-cement
and a small decrease in vitrified clay. It must be
emphasized that these figures are for total systems,
since certain pipe materials may have greater uses in
jurisdictions with special soil or water problems.
Furthermore, it must not be assumed that these
selections of pipe materials are based solely on
infiltration control criteria.
Sewer Jointing to Control Infiltration
The effectiveness of sewer joints for the control
of infiltration is so important that — axiomatically
speaking - no sewer system is better than its joints. A
good joint must be watertight, root penetration-tight,
resistant to the effects of soil and sewage, longlasting,
and flexible.
20
-------
TABLE 4
NATIONAL STATISTICAL SURVEY
SEWER PIPE MATERIAL IN USE
Number of Agencies Reporting Type of Sewer Material in Use by Type of Sewer System
Region Population Croupt
EM 200,000*
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Sub-
Total
South 200,000+
100,000-199,999
20XMO- 99,999
10,000- 19,999
Under 10,000
Sub-
Total
Mdwest 200,000+
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Sub-
Total
Soutfiwwl 200,000+
100,000-199,999
20,000- 99,099
10,000- 19,999
Under 10,000
Sub-
Total
We»t 200,000+
100,000-199.999
20,000- 99,999
10,000- 19,999
Under 10,000
Sub-
Total
Canada 200,000+
100,000-199,099
20,000- 99,990
10,000- 19,099
Under 10,000
Sub-
Total
Total
Number 'M Atbertm
in Group I Cement
9 ! 0
7 , 3
23 ! 5
5 2
1 0
45 11
8 0
6 0
10 0
4 0
0 0
28 0
4 0
6 1
16 5
7 0
2 0
35 6
7 0
2 0
10 3
4 0
2 0
25 3
7 2
8 2
30 12
11 2
3 0
59 18
4 0
2 1
10 2
3 1
2 0
21 4
213 42
Separate Sanitary
CM Reinf.
Brick Iron Concrete
200
244
6 7 10
012
0 1 0
10 13 16
035
013
055
012
000
0 10 15
1 2 1
222
3 10 9
022
000
6 16 14
345
0 2 1
045
030
000
3 13 11
245
173
1 14 15
008
0 1 1
4 26 32
00 1
0 0 1
01 2
0 0 1
0 1 1
02 6
23 80 94
PlMic Concrete Tru**
0 20-
0 30
1 11 2
1 31
0 00
2 19 3
0 30
0 30
0 60
0 00
0 00
0 12 0
0 30
0 50
0 71
0 20
0 00
0 17 1
0 62
0 00
0 40
0 03
0 00
0 10 5
1 60
1 7 0
0 10 0
1 20
1 1 0
4 26 0
0 00
0 20
0 30
0 20
0 00
0 70
6 91 9
Vitrified Alberto*
day Cement
4 0
6 0
19 0
4 0
1 0
34 0
5 0
2 1
10 0
4 0
0 0
21 1
3 0
5 0
13 2
7 0
2 0
30 2
6 0
2 0
8 0
0 0
2 0
18 0
6 0
8 1
28 2
7 0
2 0
51 3
1 0
1 0
4 0
2 0
2 0
10 0
164 a
CM
Briefc Iron
2 0
1 1
5 2
0 0
1 1
9 4
2 1
0 1
2 0
0 0
0 0
4 2
1 1
3 0
4 2
0 1
0 0
8 4
2 2
1 0
0 0
0 1
0 0
3 3
3 0
1 1
1 3
0 1
0 0
5 5
0 0
0 0
0 1
0 0
0 0
0 1
29 19
Separate Storm
Rein.
Concrete flattie Concrete Tru**
2 0
2 0
11 1
2 0
1 0
18 1
2 0
1 0
5 2
4 1
0 0
12 3
2 1
1 1
8 1
2 0
2 0
15 3
4 1
2 0
4 0
0 0
0 0
10 1
4 1
7 1
12 1
4 1
1 1
28 5
1 0
1 0
6 0
1 1
1 0
10 1
93 14
3 0
5 0
13 0
4 0
0 0
25 0
5 0
1 0
4 0
1 0
0 0
11 0
3 0
4 0
11 0
5 0
1 0
24 0
6 0
2 0
6 0
2 0
0 0
16 0
4 0
7 0
15 0
2 0
1 0
29 0
1 0
2 0
6 0
3 0
2 0
14 0
119 0
Vitrified Alberto*
Clay Cement
4 0
4 0
15 2
2 0
1 0
26 2
3 0
1 0
2 0
0 0
0 0
6 0
3 0
5 1
8 0
3 0
0 0
19 1
2 0
2 0
0 0
1 0
0 0
5 0
3 0
4 0
3 0
0 1
1 0
11 1
0 0
1 0
3 0
0 0
2 0
6 0
73 4
Combined Sewer*
CM Rein.
Vitrified
Briefc Iron Concrete Plastic Concrete Trim day
503
301
523
014
000
13 3 11
1 0 1
000
000
000
000
^
101
312
000
202
000
000
614
00 0
000
000
00 0
000
000
332
033
0 0 1
001
000
367
0 1 0
101
1 0 3
00 1
000
215
25 11 28
0 6
0 2
0 6
0 5
0 0
0 19
0 1
0 0
0 0
0 0
0 0
0 1
0 3
0 0
0 2
0 1
0 0
0 6
0 0
0 0
0 0
0 0
0 0
0 0
0 2
0 2
0 1
0 0
0 0
0 5
1 0
0 1
0 2
0 1
0 0
1 4
1 35
0 5
O 4
1 8
0 4
0 0
1 23
0 0
0 0
0 0
0 0
0 0
0 0
0 3
0 1
0 3
0 1
0 0
0 6
0 0
0 0
0 0
0 0
0 0
0 0
0 4
0 3
0 1
0 2
0 0
0 10
0 1
0 0
0 3
0 1
0 0
0 5
1 46
(1)
Note: Not all agencies in each group reported data
-------
TABLE 5
NATIONAL STATISTICAL SURVEY
SEWER PIPE MATERIAL SPECIFIED
Number of Agencies Reporting Type of Sewer Pipe Material Specified by Type of Sewer System
Separate Sanitary
Separate Storm
Combined Sewers
10
Number11
Region Population Groups in Group
East 200,000+ 9
100,000-199,999 7
20,000- 99,999 23
10,000- 19,999 S
Under 10.000 '
Sub-
Total «5
South 200,000+ 8
100.000-199,999 6
20,000- 99,999 10
10,000- 19,999 4
Under 10.000 °
Sub-
Total 2S
Midwest 200,000+ 4
100,000-199,999 6
20,000- 99,999 1fi
10,000- 19,999 1
Under 10,000 2
Sub-
Total 35
Southwest 200,000+ 7
100,000-199.999 2
20.000- 99,999 10
10.000- 19.999 4
Under 10,000 2
Sub-
Total 25
West 200.000+ 7
100.000-199,999 8
20.000- 99.999 30
10,000- 19,999 11
Under 10,000 3
Sub-
Total 59
Canada 200.000+ 4
100.000-199,999 z
20.000- 99,999 10
10,000- 19.999 3
Under 10,000 2
Sub-
Total 21
Total 213
Asbestos Cast
Cement Brick Iron
1 1 2
303
7 05
0 0 1
0 00
11 1 11
0 02
0 0 1
0 06
1 0 2
0 00
1 0 11
0 02
1 0 4
4 1 7
0 02
0 00
5 1 15
2 05
0 0 1
2 04
0 03
000
4 0 13
2 05
1 0 3
11 0 11
6 02
000
20 0 21
000
2 00
3 00
1 0 0
0 00
6 00
47 2 71
Concrete Plastic
3 1
1 0
4 1
3 0
0 0
11 2
3 0
1 1
4 2
2 0
0 0
10 3
0 0
1 1
4 2
2 0
0 1
7 4
3 0
0 0
3 0
0 0
0 0
6 0
3 3
2 1
8 0
5 1
1 1
19 6
1 1
2 1
4 0
1 0
1 0
9 2
62 17
Rein.
Concrete Truss
6 0
4 1
11 2
4 0
0 0
25 3
3 1
2 0
6 0
0 0
0 0
11 0
3 1
4 1
9 4
2 0
0 1
18 7
6 3
0 0
2 0
0 0
0 0
8 3
7 0
4 0
13 0
3 0
0 0
27 0
2 0
1 0
4 0
1 0
0 0
8 0
97 13
Vitrified Asbestos
Clay Cement
7 1
7 1
15 2
3 0
0 0
32 4
3 0
2 1
11 0
4 0
0 0
20 1
3 0
5 0
13 1
7 0
2 0
30 1
6 0
3 0
8 0
3 0
1 0
21 0
7 3
7 0
23 7
7 2
1 0
45 12
1 0
1 0
3 1
0 0
2 0
7 1
154 7
Cast
Brick Iron
1 1
0 1
0 1
0 2
0 0
1 5
0 2
0 1
0 4
0 0
0 0
0 7
0 0
0 0
1 2
0 0
0 0
1 2
0 2
0 0
0 0
0 0
0 0
0 2
0 3
0 1
0 1
1 0
0 0
1 5
0 0
0 0
0 0
0 0
0 0
0 0
3 21
Concrete Plastic
5 1
3 0
10 2
2 0
0 0
25 3
0 0
1 1
4 2
4 2
0 0
9 5
1 1
1 1
8 4
2 1
1 1
13 8
3 1
1 0
2 1
1 0
0 0
7 2
3 2
4 2
13 2
4 5
0 0
24 11
1 1
2 0
7 0
2 1
1 0
13 2
91 31
Rein.
Concrete Truss
8 0
6 0
18 0
5 0
0 0
37 0
5 0
1 0
6 0
1 0
0 0
13 0
3 0
5 0
14 0
6 0
1 7
29 7
5 0
3 0
0 0
2 0
0 0
16 0
6 0
8 0
16 0
4 1
1 0
35 1
2 0
1 0
6 0
3 0
1 0
13 0
143 2
Vitrified Asbestos
Clay Cement
6 1
3 1
10 2
0 0
0 0
19 4
0 0
1 0
1 0
1 0
0 0
3 0
0 0
1 0
5 0
1 0
0 0
7 0
0 0
0 0
0 0
0 0
0 0
0 0
3 0
3 0
3 0
1 0
0 0
10 0
0 0
2 0
2 0
0 0
2 0
6 0
45 4
Cast
Brick Iron Concr
1 1 4
000
003
0 0 1
000
1 1 8
0 1 0
000
0 1 0
000
000
020
0 1 1
000
000
000
000
0 1 1
000
000
000
000
000
000
0 2 1
0 0 1
000
0 0 1
000
023
0 0 1
000
0 0 1
0 0 1
000
003
1 6 15
Rein.
ate Plastic Concrete
1 6
0 2
0 5
0 1
0 0
1 14
0 1
0 0
0 1
0 0
0 0
0 2
0 2
0 0
0 1
0 1
0 0
0 4
0 0
0 0
0 0
0 0
0 0
0 0
0 2
0 1
0 0
0 0
0 0
0 3
0 1
0 0
0 1
0 1
0 0
0 3
1 26
Vitrifit
Truss Clay
0 6
0 2
0 8
0 1
0 0
0 17
0 0
0 0
0 1
0 0
0 0
0 1
0 1
0 0
0 2
0 0
0 0
0 3
0 0
0 0
0 0
0 1
0 0
0 1
0 2
0 0
0 0
0 0
0 0
0 2
0 0
0 0
0 6
0 0
0 0
0 0
0 25
(1)Note: Not all agencies in each group reported data
-------
Up to about 30 years ago, cement mortar was
commonly used to make sewer pipe joints. As
attention began to be given to preventing infiltration
and root intrusion into sanitary sewers, it became
evident that mortar was not a good material for this
service. Such joints were subject to shrinking and
cracking; they were rigid and tended to break loose
from pipe bells and spigots; they swelled because of
hydrogen sulfide action and caused the rupture of
pipes; they were the cause of root intrusion. To
overcome these problems, various forms of asphaltic
compound joints came into use, some hot-poured and
some pre-cast. These materials provided desired
characteristics, but they required care and skill in
application to assure watertightness.
Finally the "0" ring joint was developed. First
used on asbestos-cement pipe, it then was found
suitable for concrete and vitrified clay by casting a
plastic ring on the spigot of the pipe and a plastic
lining on the pipe's bell. "0" ring joints also were
made applicable to concrete pipe.
ASTM specification C-425, stipulating the
characteristics of a satisfactory joint for bell and
spigot vitrified clay pipe; other ASTM specifications
have been adopted for other pipe materials.
Manufacturers of plain-end vitrified clay pipes
have developed a resilient sleeve clamp for pipe ends
fastened by non corrosive metal bands; this
reportedly makes an effective joint for plain-end pipe.
Field practice indicates that the bottom of a
sewer trench is not the most ideal place to form a
joint. Jointing under such in-the-wet and often
difficult-to-see circumstances does not lend itself to
precise and careful workmanship.
Experience has shown that joints for pipes made
of PVC are particularly difficult to make where
extraneous materials such as sand and water are
present. Pipes made of ABS. have not demonstrated as
much difficulty in achieving a good joint under poor
trench conditions.
Some contractors interviewed by investigators
suggested that when adverse trench conditions are
encountered that an assembled joint, rather than a
joint which must be formed, should be used. Figure
2, Chemical Weld Joint, shows such a joint being
prepared.
Selection of Sewer Joints
The national investigation in representative
jurisdictions, involving in-depth surveys by visiting
APWA engineering research personnel, indicated that
engineering designers, municipal administrative
officials, and contractors wish to use effective joint
materials. Of the 26 jurisdictions, 24 reported using
"0" ring design; their experience confirmed the
effectiveness of this method of jointing. Other
jurisdictions reported use of neoprene gaskets; some
indicated the use of this type of material without
noting that it took the form of an "0"-type ring.
Several officials referred to the use of the ASTM
specifications C-425 for vitrified clay and sewer pipe
and C-361 for concrete and asbestos-cement pipe.
The great majority of the jurisdictions reported using
one or more of the "0" ring, rubber ring, or C-425
types of joints. Sixteen said they use mortar joints
primarily on reinforced concrete pipe. In some cases a
form of gasket is employed for watertightness, with
spaces in the joint to be filled in with mortar. Figure
3, Compression Gasket Joints, shows three types of
compression gasket joints.
Table 2, previously referred to in connection
with types of pipe in service, also contains summary
TABLE 7
Regions
NATIONAL STATISTICAL SURVEY
SEWER JOINTS IN PLACE
Number of Agencies Reporting type of Sewer Joint Material in Use on Existing Sewer Systems
(1)
Separate Sanitary
Bitumi- Comp.
nous Mortar Plastic Poured Gasket Other
Separate Storm
Bitumi- Comp.
nous Mortar Plastic Poured Gasket Other
Combined Sewers
Bitumi- Comp.
nous Mortar Plastic Poured Gasket Other
East
South
Midwest
Southwest
West
Canada
25
19
17
11
14
9
28
18
22
15
49
10
9
11
14
9
25
0
12
11
16
11
14
2
30
26
24
17
42
12
2
0
2
1
10
1
21
6
10
1
4
4
32
22
25
14
38
13
1
6
1
2
3
0
2
6
4
1
4
2
18
14
12
7
23
7
0
0
4
2
13
1
18
0
2
0
1
1
9
2
9
1
10
7
3
0
0
0
1
0
3
0
2
0
1
2
12
2
5
1
8
2
1
0
0
0
3
2
Totals
95 142
68
151
16
46
144 13
19
81
20
22
38
(1)
Note: Not all agencies have each type of sewer system
30
23
-------
FIGURE 2
CHEMICAL WELD JOINT!
Courles) : UniteJ Technology (.'enter
TABLE 6
CONSULTING ENGINEERS SURVEY
JOINTING MATERIALS
Number of Firms Reporting by Type of Sewer Joint Material Used
Rubber Rubber Mechan Molded Bitumi
Pipe Material "O" Ring Gasket ical P.V.C. nous Other
Asbestos-Cement 39 6
Cast Iron 20 17
Concrete 41 20
Plastic 9 3
Reinf. Concrete - 2
Steel 6 3
Vitrified Clay 19 S
21
1 Lead
21 Solvent
Weld
14 Welded
40
-------
information on the types of joints used in sewer pipe
construction in the 26 jurisdiction areas covered by
the representative on-site investigations.
The consulting engineering firms responding to
the survey inquiry indicated an overwhelming
preference for the "0" ring type of joints with all
applicable types of pipe. A summary tabulation of
these results is contained in Table 6, Consulting
Engineers Survey — Jointing Materials.
There may be some confusion in reporting rubber
"0" ring and rubber gasket. At any rate, these two
classifications were most frequently reported, except
on vitrified clay, in which case molded PVC was
specified with twice the frequency.
As in the case of sewer pipe material, the national
statistical survey requested information on joints now
in place and now being specified. Significantly, where
142 jurisdictions had utilized mortar joints in their
existing system, only 23 now specify this type. This is
dramatic evidence of a change in jointing practices.
Bituminous jointing material similarly has been
dropped from many specifications while usage of
plastic and rubber "O" rings has increased. The
complete results are shown in Table 7, National
Statistical Survey - Sewer Joints in Place, and Table
8, National Statistical Survey - Sewer Joints.
Specified.
The survey disclosed one striking consensus:
consulting engineers are unanimous in the opinion
that infiltration has decreased markedly in recent
years because of improvements in pipe manufacture
and joint materials.
FIGURES
OPEN JOINT
Courtesy K. T. Snyder Co., Inc.
CLOSED JOINT
CONCRETE TONGUE AND GROOVE PIPE
Courtesy Certain-teed Products Corp.
DOUBLE COMPRESSION GASKET
ASBESTOS-CEMENT PIPE
CUT-AWAY VIEW OF COMPRESSION GASKET JOINT
Courtesy: United Technology Center
25
-------
TABLE 8
NATIONAL STATISTICAL SURVEY
SEWER JOINTS SPECIFIED
Number of Agencies Reporting Type of Sewer Joint Material Specified by Type of Sewer System*
Combined Sewers
to
O\
Region Population Groups
East 200,000+
100,000-199,999
20,000- 99,999
10.000- 19,999
Under 10,000
Sub-
Total
South 200,000+
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Sub-
Total
Midwest 200,000+
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Sub-
Total
South west 200,000+
100,000-199,999
20.000- 99.999
10,000- 19,999
Under 10,000
Sub-
Total
West 200,000+
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Sub-
Total
Canada 200,000+
100.000-199,999
20,000- 99,999
10.000- 19.999
Under 10,000
Sub-
Total
Total
Number'1
in Group
9
7
23
5
1
45
8
6
10
4
0
28
4
6
16
7
2
36
7
2
10
4
2
25
7
8
30
11
3
59
4
2
10
3
2
21
213
Bitumi-
nous Mortar
2 0
2 3
5 3
1 0
0 0
10 6
0 0
0 2
0 1
1 2
0 0
1 5
0 0
0 0
3 0
1 0
0 0
4 0
1 1
0 0
0 0
0 1
0 0
1 2
1 1
0 1
1 2
0 0
0 1
2 5
0 1
1 0
1 2
1 1
2 1
5 5
23 23
Plastic Poured
2 0
2 1
7 5
0 0
0 0
11 6
2 0
3 3
5 2
1 2
0 0
11 7
3 0
4 1
5 3
2 0
0 0
14 4
4 2
1 1
3 1
2 0
0 0
10 4
5 2
4 1
15 2
6 0
1 0
31 5
0 1
0 0
0 0
0 0
0 0
0 1
77 27
at J
Rubber
Ring
4
7
20
4
1
36
7
4
10
5
0
26
3
4
9
6
1
23
6
1
10
1
1
19
6
6
21
9
2
44
1
2
7
2
0
12
160
Bitumi-
Other NA nous
023
002
215
003
000
2 3 13
000
000
000
0 0 1
000
0 0 1
0 1 1
003
0 1 7
0 0 1
010
0 3 12
202
000
002
0 1 0
0 1 0
224
200
1 0 0
442
200
000
942
1 0 0
000
002
0 0 1
002
1 0 5
14 11 37
Mortar Plastic
2 1
6 1
10 1
3 0
1 0
22 3
2 0
2 2
5 5
2 1
0 0
11 8
2 0
2 0
9 1
4 1
1 0
18 2
3 2
2 0
5 2
1 0
0 0
11 4
2 2
3 2
17 3
4 2
1 0
27 9
2 0
2 0
6 0
1 0
2 0
13 0
102 26
Rubber
Poured Ring
0 4
1 4
1 13
1 2
0 0
3 23
1 6
2 2
1 5
0 3
0 0
4 16
0 2
0 3
0 7
0 3
0 1
0 16
0 3
0 0
0 4
0 0
0 0
0 7
1 4
0 4
1 10
0 6
0 0
2 24
1 1
0 1
0 4
0 1
0 0
1 7
10 93
Bitumi-
Other NA
0 1
0 1
1 3
0 0
0 0
1 5
0 0
0 2
0 3
0 1
0 0
0 6
0 1
0 0
0 0
0 1
0 0
0 2
1 0
0 0
0 4
0 3
0 2
1 9
1 2
3 0
4 10
3 2
1 1
12 15
1 0
0 0
1 0
0 0
0 0
2 0
16 36
nous Mortar
3 0
0 1
2 2
0 0
0 0
5 3
0 0
0 0
0 0
0 0
0 0
0 0
0 1
0 0
2 1
0 0
0 1
2 3
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
1 1
0 0
0 0
0 0
0 0
1 1
8 7
Plastic Poured
2 0
0 0
1 2
0 0
0 0
3 2
0 0
0 0
0 0
0 0
0 0
0 0
2 0
0 0
0 0
0 0
0 0
2 0
0 0
0 0
0 0
0 0
0 0
0 0
1 1
0 0
0 0
0 0
0 0
1 1
0 0
0 0
0 0
0 0
0 0
0 0
6 3
Rubber
Ring Other NA
4 0 1
204
7 1 14
1 0 4
0 0 1
14 1 24
206
0 0 6
0 0 10
004
0 0 0
2 0 26
202
006
2 0 11
007
001
4 0 27
007
002
0 0 10
1 0 3
002
1 0 24
205
1 0 7
0 ,, 0 32
11 10
003
4 "' 1 57
0 1 1
1 0 t
1 1 8
1 0 2
002
3 2 14
28 4 155
-------
Design Considerations
Sewer design should be a well-developed
technique after many years of refinement and
experience. However, although hydraulic and
structural design of conduits has been researched
thoroughly and perfected, designers and sewer system
administrators and operators still have basic
differences of opinion on the proper practices to
control excessive infiltration.
While many of these points of difference are
related to general sewer design, they have a direct
bearing on infiltration control. That is because basic
design and construction practices may affect the
integrity of the system and, hence, the amount of
infiltration during service. One point of great
significance came to light during the national study:
the vital need for preplanning funds prior to actual
design, to determine soil and ground water conditions
and existing sources of infiltration and their effect on
pumping and treatment facilities. Presently, local,
state, and Federal agencies do not fully recognize the
basic importance of adequate review and evaluation
of existing facilities and proper planning before
adding new sewer system facilities. The inadequacies
in preplanning practices, as well as in actual design
procedures, include:
1. Average and peak design flows too often are
calculated on the basis of standard textbook
criteria unrelated to the actual conditions for
the area under design.
2. The units used to delineate design flows vary
widely and at times seem inappropriate for
separate sanitary sewer design. As an
example, the correlation between "gallons
per acre per day" and actual sanitary sewage
flows often is indeterminate.
3. Too much sewer design is undertaken
without adequate subsurface knowledge or
investigation.
4. There is inadequate communication and a
lack of understanding between sewer design
engineers and sewer maintenance personnel.
Designers, unfortunately, are not always
aware of the in-the-field problems of
maintenance; conversely, maintenance staffs
solve daily sewer surcharge difficulties by use
of "seat-of-the-pants" expedients which very
often are not reported to the sewer officials
or design engineers.
5. The design engineers too frequently have
their association with a project severed after
they review the bids. Often there is no
continuity between design decisions and the
most critical phase — the construction phase.
Design Criteria
When asked if control of excessive infiltration
was a problem in their design work, two-thirds of the
consulting engineering firms participating in the
survey answered "yes" and one-third "no." These
opinions may support the national survey of
statistically chosen and surveyed jurisdictions in its
findings that some sections of the country do not
experience the ground water or rainfall conditions
which make infiltration an overriding consideration in
either sewer design or maintenance. These consulting
engineers' findings may indicate a need on the part of
designers for more positive recognition of the
problem of infiltration. Betokening this need is the
awareness that service and maintenance personnel,
contractors, and pipe manufacturers show toward
that problem.
The consulting engineers were asked if the
allowances they used for infiltration/inflow in sewer
capacity design were different from those for
infiltration in specific sewer construction projects.
The responses were equally divided between "yes"
and "no." They reflected a lack of consistency on the
basic concept of design flow for sanitary sewers. The
same inconsistency was demonstrated in the
responses from jurisdictions surveyed for the purpose
of determining statistical averages that would
represent national practices in infiltration prevention
and control. Data covering the national survey will be
discussed later.
Table 9 presents a summary of the Consulting
Engineers Survey — Sewer Infiltration Design
Allowances. The 66 firms responding to the survey
reported the use of 35 different sewer design
standards or infiltration allowances. These varied
from "none" to amounts such as 15,000 gallons per
mile per day. They gave clear evidence of limited
standardization.
The survey indicated considerable confusion over
the terminology and measurement units for
infiltration allowances. Some design engineers seem
to feel mat infiltration design allowances and
infiltration construction allowances are one and the
same. Others indicate they are completely different
and should be stipulated by different units and
standards of measurement.
The national statistical survey provided data on
similar facets of sewer design and construction
pertinent to infiltration conditions and control
practices.
As discussed previously, considerable variation in
units and terminology also was indicated in
jurisdictions replying to this survey. The survey
showed the use of total peak flow allowances and
27
-------
TABLE 9
CONSULTING ENGINEERS SURVEY
SEWER INFILTRATION DESIGN ALLOWANCES
United States Responses
None
Included in gpcd
No answer
Variable
500 gpad
500-2,000 gpad
1,000-1,200 gpad
15,000 gpmd (8 in.}-20,000 gpmd (18 in.)
90 gpcd + 10-20 gpcd for infil./inflow
Not applicable
500-1,000 gpad
4 times normal sanitary flow
Formula
500 gpimd
300-2,000 gpad
100 gpcd
.0088 cfs/a
1,600-3,500 gpad
200-400 gpcd
500-700 gpad
40gpi/1,000ft.
133-250 gpimd
400-6,000 gpad
21/2 times sanitary flow
250 gpimd
200 gpimd
ASCE recommendation
30 gpcd additional
.1-.3cfs/100a
125 gpimd
Not permitted by State
30 gal ./acre/unit Density
Canadian Responses
No inflow allowed
.004 cfs/a
Varies
300 gpcd + 1,000 gpad
.002-.004 cfs/a
Number of Replies
1
1
7
2
2
1
1
1
1
6
3
2
1
4
2
3
1
1
2
1
1
1
1
Number of Replies
1
1
3
1
1
Note: These abbreviations are used for Tables 9,10,11,12 and 13.
gpad—Gallons per acre per day
gpcd—Gallons per capita per day
gpid-Gallons per inch diameter
gpimd—Gallons per inch-mile per day
gpmd—Gallons per miles per day
Imp—Imperial gallons
a—Acre
adf—Average daily flow
cfs—Cubic feet per second
cfs a—Cubic feet per second per acre
dia—Diameter
DU—dwelling unit
dwf—Dry weather flow
ft-Foot
NA—Not applicable
x—Times
28
-------
typical construction type standards. Some criteria
were related to drainage areas and some to pipe size
and length; a few were based on per capita
contribution, and a number on percentage relatioship
of dry weather to average flow. When almost 100
different criteria are reported by some 200
jurisdictions, it is evident that little standardization is
in effect. Part of the problem lies in indistinctly
defined concepts - first, of design allowances in
general, and second, of infiltration or total
extraneous water allowances in particular. Table 10,
National Statistical Survey - Infiltration Design
Allowances, records the current practice by region
and population in the United States and Canada.
Construction Considerations
The physical environment in a 10- or
20-feet-deep sewer trench, with water, mud, silt, and
debris, coupled with excessive cold or heat, does not
lend itself to optimum human or material
performance in joint construction. Years ago, in the
use of mortar or poured joints, many incomplete ones
were left in the ground after construction. Today,
even with relatively workable and effective jointing
techniques, TV inspection cameras still find joint
materials omitted or misplaced and the defective
joints subject to unimpeded entry of ground water or
exfiltration of waste waters. The only insurance
against poor construction is vigilance and unremitting
control. Positive steps which should be taken,
include:
1. Provide funds for adequate preliminary
investigation of soils, ground water,
foundation, and condition of existing
system;
2. Recognize the relationship between design
and the problems of maintenance;
3. Keep the design engineer in the
picture — making him responsible for placing
his design into full and efficient operation
without infiltration;
4. Control quality of all phases of construction
and inspection;
5. Provide adequate and constant inspection by
personnel responsible to, and paid by, the
owner;
6. Test short sections of pipe frequently for
acceptance by the owner;
7. Use TV or photographic checking and
recording of sewer interiors as an inspection
technique, paid for by the owner;
8. Require that all repairs and correction be
made at the contractor's expense before
connection of building sewers;
9. Check on all repairs by TV or photography
at contractor's expense, and
10. Inspect, correct, and accept small sections as
they are completed so that the entire system
can be checked for tightness, unit-by-unit,
rather than by a total test at the end of
construction.
Table 11, Consulting Engineers
Survey — Infiltration Construction Allowances, lists
the construction allowances used by 66 firms. In
contrast to the design allowances summary, Table 11
indicates there is more consistency in the units of
infiltration volumes, although there still is wide
variation in actual allowances. By far the most
commonly used allowance standard is 500 gallons per
inch of pipe diameter per mile per day. This
allowance gained technical credence when first used
in the so-called "Ten-States Standards." It is
significant that the states involved in developing these
design criteria for sewage works facilities intended
them to be a guideline rather than a standard.
Nevertheless, the 500-gallon allowance has been
widely adopted by many states, jurisdictions, and
consulting firms.
Fortunately, unquestioned acceptance of the
500-gallon criterion is being superseded by lower and
more realistic design and construction allowances,
based on the greater potential infiltration control
capabilities of new products, better inspection and
testing procedures, and greater control of
construction methods. The consulting engineers'
survey confirmed this new and important trend.
The infiltration construction allowances reported
by the 212 jurisdictions in the United States and
Canada are listed in Table 12, National Statistical
Survey — Infiltration Construction Allowances. The
results, as expected, are similar to the consultant's
data, since most jurisdictions are served by
consultants in this area of sanitary engineering
criteria. Here again, there are fewer different
allowances for construction than for design, and more
uniformity of terminology. The concept of checking
compliance with an infiltration construction
allowance, as a condition for acceptance, is quite
universally recognized and used. The use of
allowances for excess flows in sewer system design
may be recognized, but there is little uniformity in
approach and results.
Once again, the "Ten-States Standards" of 500
gallons per inch of diameter per mile per day is the
most frequently used. This standard is found in all
regions and all population groups.
Water pollution control agencies of the 50 states
and eight Canadian provinces revealed an even greater
29
-------
TABLE 10
NATIONAL STATISTICAL SURVEY
INFILTRATION DESIGN ALLOWANCES
Number of Agencies Reporting Infiltration Design Allowances by Population Group
Population
Region No.
East 4
1
1
1
1
1
South 1
1
1
1
1
1
1
1
Midwest 1
1
1
1
Southwest 1
1
1
1
1
2
West 1
1
1
1
1
1
1
Canada 1
2
1
Over
200.000
Allowance
no ans.
no design
allowance
2.5 x dwf
5,000 gpad
1,000-1,500 gpad
19,556 gpad
no ans.
85% dwf
250% dwf
0.4 cfs a
300 gpimd
400-750 gpimd
15.000 gpmd
25,000 gpmd
no ans.
20 gpcd
65 gpcd
0.013 cfs a
no design1
allowance
50% dwf
100 gpcd
750 gpad
1,500-3.000 gpad
500 gpimd
-0-
no ans.
20% dwf
600-2,000 gpad
1.100 goad
1,350 gpad above
g.w. table
2,750 gpad below
g.w. table
0.001-0.003 cfs a
no ans
no design
allowance
200 gpad
No.
2
1
1
1
1
1
1
1
1
1
1
1
1
2
2
1
1
1
1
2
1
1
1
1
1
1
1
100.000-
199,999
Allowance
no ans.
no design
allowance
10 gpcd
3.000 gpad
10,000 gpmd
400 gpd (no
units given)
no ans.
30% dwf
25 gpcd
100 gpcd
300 gpad
750 gpad
varies
400 gpimd
500 gpimd
0.01 cfs a
1,000 gpimd
2.5 -4 x dwf
1,500 gpad
no ans.
no ans.
100% dwf
100-300% dwf
30 gpcd
634 gpimd
22,222 gpmd
0.002 cfs a
0.009 cfs a
No.
16
1
1
1
1
1
1
1
3
1
1
1
2
1
1
1
8
2
1
1
1
1
1
1
7
2
2
1
1
1
3
1
1
12
3
2
1
1
1
1
2
1
1
1
3
1
1
1
2
1
1
1
1
1
20.000-
99,000
Allowance No.
no ans. 3
no design
allowance
varies 1
-0-
Sxdwf
15% dwf 1
200 gpimd
5.000 gpmd
no ans. 3
100% dwf 1
225% dwf
20 gpcd
500 gpimd
0.0015 cfs a
2,640 gpmd
-0-
no ans. 7
10% dwf
20% dwf
4 x dwf (under 8 in.
diameter)
2.5 x dwf (18-42 in.
diameter)
1.5 x dwf (over 42 in.
diameter)
2.4 gph 1,100ft.
100 gpcd
1.000-1,500 gpad
200 gpimd
300 gpimd
500 gpimd
no ans. 1
-0- 1
50% dwf 1
317 gpimd 1
500 gpimd
650 gpimd
750 gpimd
no ans. 5
no design 4
allowance
10% of capacity 1
50% dwf 1
3xdwf
250 gpad
500 gpad
1.000 gpad
1.100 gpad
5,000 gpad
10,000 gpad
500 gpimd
no ans. 1
no design 1
allowance
12 gpimd 1
300 gpad
2,000 gpad
0.001 56 cfs a
1,500 gpimd (imp)
1.667 gpimd (imp)
1.300 gpad (imp)
10.000- Under
19,999 10,000
Allowance No. Allowance
no ans. 1 10.000 gpmd
30 gpcd
2,000 gpad
no ans.
20% dwf
1 no ans.
no ans. 1 2,000 gpmd
no ans. 1 no ans.
no design 1 no design
allowance allowance
10% dwf
100 gpcd
no ans. 1 no ans.
no design 2 no design
allowance allowance
507 gpimd
12.672 gpmd
no ans. 1 no ans.
no design 1 no ans.
allowance
3xdwf
NOTE 1. Some allowance* which were given for less
than • day or for less than a mite have been converted
to amounts per mile per day.
NOTE 2. Where no design allowance are reported, it
impttet that agency hat not established or does not
use a standard criteria for design. This may be
because of the use of combined sewers, or because all
design is by consultants who are allowed to use their
own criteria.
30
-------
TABLE 11
CONSULTING ENGINEERS SURVEY
INFILTRATION CONSTRUCTION ALLOWANCES
United States Responses
No answer
1,000 gpimd
500 gpimd
50 gpi 71,000 ft./day
.1 gal/in/1,000ft./day
600 gpimd
15,000 gpimd-20,000 gpimd
200 gpimd
1250 gpad-uplands; 2750 gpad-lowlands
100 gpimd
None
350 gpimd
100gpi/1,000ft./day
250 gpimd
200-500 gpimd
Ten states
10gpi/100ft./day
40gpi/1,000ft./day
.2gpi/100ft./day
150 gpimd
245 gpimd
50 gpimd
125 gpimd
50-100 gpimd
300 gpimd
Canada Responses
a formula
200 gpimd
.004-.0032 cfs
312 gpimd
No ans.
.2-.8gpi/100ft./hr.
Number of Replies
2
1
15
1
1
1
1
7
1
6
2
1
1
5
2
1
1
1
1
3
1
1
1
1
1
reliance on the allowance of 500 gallons per inch of
diameter per mile per day. This is understandable
since that figure originally was set as a guideline by
representatives of a number of state agencies.
Thirty-two states and provinces stipulate this
allowance, showing how such guidelines evolve into
standards and are adopted by many contiguous
jurisdictions. Surprisingly, 11 jurisdictions do not, or
have not, set any standards for allowable infiltration.
Table 13, State and Provincial Survey -Infiltration
Allowances, lists these survey results.
In view of the importance of full control over
sewer construction if infiltration is to be held to a
minimum, consultants were asked if they were
retained to supervise construction of the systems they
design. Ninety-five percent reported they had been so
retained. This figure must be contrasted with the
findings of interviewers who made in-depth
31
-------
TABLE 12
NATIONAL STATISTICAL SURVEY
INFILTRATION CONSTRUCTION ALLOWANCES
Number of Agencies Reporting Infiltration Construction Allowances by Population Group
Population
Region
East
South
Midwest
Southwest
West
Canada
No.
1
3
1
1
1
1
1
1
2
1
2
1
2
1
1
2
2
1
2
1
1
1
1
1
1
Over
200,000
Allowance
no ans.
no const.
allowance2
53 gpimd
1 50-300 gpimd
300 gpimd
500 gpimd
634 gpimd
no ans.
250 gpimd
300gpmd
500 gpimd
10.000 gpmd
no const.
allowance
0.003 cfs a
400 gpimd
no const.
allownace
250 gpimd
500 gpimd
1,000 gpimd
10,000 gpmd
no ans.
5%dwf
0.001-0.003 cfs a
500 gpimd
507 gpimd
(3168 + 50 D in.)]
gpmd
none
158 gpimd (imp)
500- 1,000 gpimd
(imp)
634 gpimd (imp)
No.
1
1
1
1
1
1
1
2
1
1
1
1
2
1
1
2
1
1
4
1
1
1
1
2
100,000-
199,999
Allowance
no ans.
250 gpimd
360 gpimd
500 gpimd
2.000 gpmd
5,000 gpmd 8"
10,000 gpmd (max)
200 gpd (no units
given)
100 gpimd
300 gpimd
500 gpimd
520 gpimd
1,320 gpimd
no ans.
200 gpimd
250 gpimd
500 gpimd
no ans.
400 gpimd
no ans.
no const.
allowance
igOgimdxvTT
100 gpimd
0.00619 cfs a
no const.
allowance
No.
10
3
1
1
1
1
4
1
1
4
1
3
1
1
5
1
1
2
1
10
1
3
2
1
2
1
14
2
1
1
1
7
1
2
1
3
2
1
1
1
1
1
20,000-
99,000
Allowance
no ans.
no const.
allowance
1 gpmd
150 gpimd
200 gpimd
300 gpimd
500 gpimd
792 gpimd
5,000 gpmd
no ans.
200 gpimd
500 gpimd
500 gpimd (to
30 in. diam.)
9,000 gpimd (over
30 in. diam.)
1,320 gpimd
no ans.
7,850 gpmd
100 gpimd
200 gpimd
300 gpimd
500 gpimd
1,000 gpimd
no ans.
no const.
allowance
-0-
500 gpimd
Okla. state1
no ans.
no const.
allowance
1.100 gpmd
10.000 gpmd
100 gpimd
500 gpimd
634 gpimd
760 gpimd
-190 gpimd xx/H
no ans.
no const
allowance
12 gpimd
240 gpimd (imp)
500 gpimd (imp)
3.168 gpmd
1,500-2.000 gpad
No.
1
1
1
2
2
1
1
5
1
1
2
1
1
5
1
1
1
1
1
1
1
1
1
10,000-
19,999
Allowance No.
1
no const
allowance
50 gpimd
200 gpimd
500 gpimd
no ans.
500 gpimd
30,000 gpmd
no ans. 1
400 gpimd 1
5 gal/day/sq.yd.
of interior surface
no ans.
no const 1
allowance
10,000 gpmd 1
no ans. 1
no const. 2
allowance
0.1 gpd/sqftof
wetted surface
190gimdx\/rr
507 gpimd
637 gpimd
1,267 gpimd
no ans.
no const 1
allowance
3xdwf 1
Under
10.000
Allowance
3000 gpmd
no ans.
10,000 gpmd
no const.
allowance
Okla. state
no ans.
no const.
allowance
no am.
792-1,056 gpimd
(imp)
1 Some allowances which were given for less than a
day or for less than a mile have been converted to
amounts per mile per day.
2 Where no design allowances are reported, it implies
that agency has not established or does not use a
standard criteria for design. This may be because of
the use of combined sewer, or because all design is by
consultants who are allowed to use their own criteria.
32
-------
TABLE 13
STATE AND PROVINCIAL SURVEY
INFILTRATION ALLOWANCES
No. Reporting
Allowance Agencies
1,000gpimd 1
650 gpimd 1
500 gpimd 32
300 gpimd 3
250 gpimd 1
.25 Imp. gal./in. dia./lOO ft./day 1
10,000 gpmd 2
New England Interstates Guides 1
ASTM - C425-66T 1
Relatively tight 1
Varies 3
Standards not set 11
in-the-field investigations of practices in the 26
representative jurisdictions chosen for this type of
research. They indicated the designers often are not
the individuals who make inspections or are kept
apprised of the construction inspection experiences.
Closer liaison is needed between those who design
and those who supervise construction of design
concepts, even though separate staffs of jurisdictions
or consulting firms carry out the two functions.
Another question explored with consultants was
whether or not sewers, after laying and inspection,
are found to comply with infiltration construction
allowances. All the firms replied in the affirmative,
although many answers were qualified with references
to "after correction." Obviously, for a construction
project to be completed and accepted, the system
must pass some form of test and inspection. This
means that infiltration construction allowances must
be met although their severity and strictness may vary
considerably. The problem of acceptance suggests
another consideration: that the ability of sewer pipe
and sewer joints to retain infiltration-free conditions
should be determined. A test made a few hours after
completion of a sewer line may not be representative
of conditions that will exist even a few days later
when ground water levels may change, or a few
months and years later when differential settlements
may occur and deterioration of joints and pipes may
take their toll. Infiltration, therefore, is not a static
situation. Even the best sewer system may develop
leaks after years of service. Good products and good
construction practices are the best insurance against
such long-term defects.
Consultants reported they seldom vary their
design and construction infiltration allowances to
meet different soil and ground water conditions.
Ninety percent cited no variations to meet soil
conditions. Sixty-six percent reported no such
variations for ground water conditions. These findings
indicated little dependence on the effect construction
conditions have on infiltration rates. On the other
hand, if basic design and construction criteria take
cognizance of the conditions under which sewers will
be laid, any further relaxation or tightening of
infiltration allowances to meet varying conditions
probably would be unnecessary or inadvisable.
Survey Results on Inspection and Testing
The 50 state and eight provincial agencies were
asked if they inspect sewer projects for design
compliance. Twenty-one said "yes," 34 said "no,"
and three gave no response.
These state and provincial agencies were asked if
their municipalities carry out construction inspection
and testing for leakage. Only two reported no such
control, but 11 did not respond or indicated they did
not know.
The survey results show that the emphasis on
testing and inspection lies at the local level, where it
properly belongs; but there is need for more interest
and activity at higher governmental levels. State
agencies reported they do not have adequate staff to
become involved in extensive construction inspection.
Sixty-six consulting firms responded to a request
for information on the methods of testing they use.
Fifty reported infiltration testing, three reported
smoke testing, and one listed television inspection
methods. It is obvious that many consulting firms
utilize more than one method to meet varying
conditions which require different test procedures.
The national statistical survey indicated an
increasing appreciation of the importance of good
inspection and found this type of job control
mandatory in a great majority of jurisdictions. The
relationship between improved inspectional work and
adherence to infiltration requirements is obvious.
Table 14, National Statistical Survey - Construc-
tion Inspection, summarizes the responses of more
than 212 jurisdictions on the responsibility for
inspections. In general, all construction is inspected
by someone, and only half those reporting use their
consultants for this purpose.
In the national statistical survey, the jurisdictions
33
-------
Subtotals:
East
South
Midwest
Southwest
West
Canada
200,000+
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Totals
TABLE 14
NATIONAL STATISTICAL SURVEY
CONSTRUCTION INSPECTIONS*
City Consultants Not Inspected No Answer
44
28
34
24
52
21
39
30
94
30
10
203
19
19
18
11
18
9
14
14
48
13
5
94
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
1
0
0
0
*Many agencies give more than one reply
were asked if new sewer construction is tested for
leakage. One hundred and seven reported
affirmatively, but 59 had no such control methods
and 18 did not answer. The summary of these replies
is given by regions and population groups in Table 15,
National Statistical Survey — Are Sewers Tested for
Leakage?
The 212 jurisdictions were asked to list their
methods of testing. Table 16, National Statistical
Survey - Testing Methods, presents a summary of
responses by regions and population groups. Table
17, National Statistical Survey — Testing Methods,
Totals by Population Group, is a compilation of these
methods by population groups only. In these
tabulations the predominance of exfiltration testing
becomes evident. A total of 61 jurisdictions reported
use of exfiltration, 43 use infiltration, and 27 specify
air testing. The tendency to adopt the new air test
procedure seems to be growing. Television inspection
also is reported in a number of cases; its application
as an inspection tool is wider than for construction
testing and sewer acceptance purposes.
some infiltration can occur from water held
interstitially within the soil or percolating through
the soil on its way to the ground water table during a
period of precipitation, thaw, or drainage of surface
waters.
TABLE 15
NATIONAL STATISTICAL SURVEY
ARE SEWERS TESTED FOR LEAKAGE?
Response
By Regions
Ground Water and Soil Conditions
Ground water levels are the major factor
influencing infiltration rates if the sewer structure is
not watertight. True, total or partial immersion of a
leaking sewer structure in standing ground water
offers the greatest hazard of infiltration. However,
East
South
Midwest
Southwest
West
Canada
Response By
Population Groups
200,000+
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Total
Yes
32
22
23
14
51
6
No
12
6
10
10
8
15
No Answer
1
0
2
1
0
0
27
72
21
3
148
14
3
26
11
7
61
0
1
1
2
0
34
-------
Method
TABLE 16
NATIONAL STATISTICAL SURVEY
INFILTRATION TESTING METHODS
Region
East South Midwest Southwest West Canada
Note: Not all agencies in each group reported data
TABLE 17
NATIONAL STATISTICAL SURVEY
INFILTRATION TESTING METHODS
Totals by Population Group
Total
Exfiltration
Infiltration
Visual
Air
TV
Smoke
Various
No Test Used
No Answer
14
10
5
1
—
2
1
14
4
7
11
4
—
4
4
_
6
—
3
12
4
1
4
1
—
8
4
7
6
2
—
—
—
—
7
7
39
5
—
23
3
—
1
3
6
3
3
—
—
1
—
—
15
—
73
47
15
25
12
7
2
53
21
Method
Exfiltration
Infiltration
Visual
Air
TV
Smoke
Various
No Test Used
No Answer
Over
200,000
11
10
3
3
1
—
—
11
4
100,000
199,999
9
13
4
3
4
2
—
3
2
20,000
99,999
41
15
4
15
6
2
25
6
10,000
19,999
10
9
4
3
1
2
9
6
Under
10,000
2
—
_
1
5
2
35
-------
The more than 200 jurisdictions in the national
statistical survey were questioned about the
percentages of their sewer systems laid in or below
ground water tables during dry seasons and wet
seasons. Table 18, National Statistical
Survey-Percentage of Sewers Reported Below
Ground Water Table, summarizes the responses to
this inquiry, categorized into five regions of the
nation and Canada and five population groups.
Regional variations in ground water conditions exist.
Many respondents could make no accurate estimate
of the percentages of their sewers inundated or
partially submerged in ground water.
Figure 4, Well-Point System, is a photograph of a
large diameter sewer being laid in the "dry" by use of
a well-point system to dewater the trench.
Figure 5, Sewer Construction Under Water, is
photographs of 8-inch vitrified clay pipe being laid by
skin-divers in a trench which is impossible to dewater
because the sewer is laid in coral rock and ground
water is extremely high. The pipe was laid on
sandbagged stone bedding which is shown on the
ditch bank.
Sewers laid in ground water were more prevalent
in the East, Midwest, and West, than in the South and
Southwest. As might be expected, the areas of the
nation with low precipitation conditions reported
somewhat less sewer construction in ground water
than areas prevailingly wetter. The total responses
from the United States and Canada showed that 7
percent have more than 50 percent of their sewer
systems under ground water tables during dry
weather; 15 percent have over 50 percent of their
systems under those tables during wet-weather
conditions. In general, very few jurisdictions reported
their sewers never were under the ground water table.
These results indicate that the primary ingredient for
infiltration - water - affects sewer systems in most
sections of the United States and Canada, at least
during certain periods of the year.
Because of the relationship between ground
water levels and precipitation, the jurisdictions
involved in the surveys were asked to report their
annual precipitation. These data are summarized in
Table 19, Annual Rainfall and Maximum Months. In
the East, all average rainfall figures were divided
between the ranges 21 to 40 inches and 41 to 70
inches.
In the South, a greater percentage of
communities reported rainfall in the 41- to 70-inch
range. In the Midwest, the total rainfall figures
dropped, with the majority reporting total
precipitation in the 21- to 40-inch range. In the
Southwest, as might be expected, total annual rainfall
was the lowest for the nation. While a majority of
that region's jurisdictions experienced 21 to 40 inches
annually, half of them had totals in the 0- to 21-inch
range. The Far West presented the widest variation in
rainfall conditions, but the majority reported annual
totals in the 0- to 20-inch range.
The survey brought to light a few notable
exceptions where climatic and geological conditions
provided unusually high rainfall, such as over 100
inches a year in Hawaii. Canadian jurisdictions
reported annual precipitation in all the range
categories used in the national evaluation. The
number listed in the 0- to 20-inch range
predominated. Despite local variations in national
data, it can be said that the annual precipitation is
relatively uniform for all regions. Obviously, some of
the more arid Western states do not experience
infiltration problems because the ground water table
is extremely low. This was affirmed by the survey of
state water pollution control agency practices and
experiences.
Maximum monthly precipitation was reported to
occur at various times of the year, primarily from
April to September. Scattered cases of maximum
precipitation during the winter and late fall months
were disclosed in some areas, particularly along the
west coast of the United States.
Another factor affecting infiltration rates, often
overlooked, relates not only to the presence of water
in the soil but also to the soil's nature and
permeability. A tight soil actually might tend to seal
sewer defects, even though a conduit is wet or
immersed, if aquifer waters cannot flow readily
through the voids of the soil and find entrance into
the pipe system. Conversely, trenches for sewer lines
in rock or hardpan clay, backfilled with porous
material, act as conduits for ground or surface waters
which penetrate the trench.
A review of the general classifications of soil
conditions in the surveyed communities is contained
in Table 20, National Statistical Survey - Soil
Conditions at Sewer Locations. In all five regions in
the United States and in Canada, clayey soil
conditions predominated over sandy soil or rock
formations. The Southwest was the only region
reporting more rock than sandy soil. The results
indicate it is difficult to assign specific soil conditions
to any section of the country or even to any
geological region. Jurisdictional officials, consulting
engineers, and contractors must be prepared to make
independent examinations and tests of soil conditions
as the basis for design and construction of new sewers
36
-------
Region
East
South
Midwest
Southwest
West
Canada
Total
TABLE 18
NATIONAL STATISTICAL SURVEY
PERCENTAGE OF SEWERS BELOW GROUND WATER TABLE
Population
200,000+
Weather
Ranges
No Answer
0- 25%
26- 50%
51- 75%
76-100%
No Answer
0- 25%
26- 50%
51- 75%
76-100%
No Answer
0- 25%
26- 50%
51- 75%
76-100%
No Answer
0- 25%
26- 50%
51- 75%
76-100%
No Answer
.0- 25%
26- 50%
51- 75%
76-100%
No Answer
0- 25%
26- 50%
51- 75%
76-100%
No Answer
0- 25%
26- 50%
51- 75%
76-100%
Dry
6
3
3
3
1
1
1
2
1
2
4
1
1
6
4
17
18
1
1
2
Wet
6
3
4
2
1
1
2
2
3
3
1
1
4
1
1
4
19
14
3
2
1
100,000-
199,999
Weather
Dry
3
2
2
3
2
1
2
4
2
1
4
2
1
1
1
12
13
2
3
1
Wet
3
2
1
1
3
2
1
3
2
1
1
1
2
3
2
1
2
14
10
3
2
3
20,000-
99,999
Weather
Dry
16
3
4
3
4
1
2
2
12
2
2
7
1
8
19
2
1
5
5
36
50
10
3
—
Wet
17
1
3
2
3
3
2
2
2
9
4
1
2
6
1
1
13
10
2
1
4
5
5
42
34
9
4
10
10,000-
19,999
Weather
Dry
3
2
3
1
3
4
1
2
1
1
4
6
1
1
2
1
13
18
1
1
2
Wet
4
1
3
1
4
3
2
2
3
6
1
1
1
1
1
17
13
1
2
2
Under Totals
10,000
Weather Weather
Dry Wet Dry
28
10
1 5
1 2
12
10
2
3
1
8
1 1 23
2
1 1 2
6
1 1 14
1
1 1 2
1 2
2 2 15
1 1 36
5
3
1 1 12
1 1 9
1
3 3 81
4 4 102
1 - 15
1 8
227
Wet
30
7
3
2
3
13
7
1
3
4
17
17
5
2
8
13
1
2
1
21
24
5
4
5
13
7
1
95
75
16
TO
17
37
-------
FIGURE 4
WELL-POINT SYSTEM
(. iiufle>> L nilod Stales I'unircir 1'ipc I n.
SEWER CONSTRUCTION UNDER WATER
-------
TABLE 19
NATIONAL STATISTICAL SURVEY
ANNUAL RAINFALL AND MAXIMUM MONTHS
Annual Rainfall (in.) Max. Monthly Rainfall (in.) When Max. Rainfall Occurs
Range
Region
East 0- 20
40
70
100
100 +
No Answer
South 0- 20
40
70
100
100 +
No Answer
Midwest 0- 20
40
70
100
100
No Answer
No. of
Munici-
palities
—
15
19
-
-
11
1
4
18
4
-
1
4
22
(
_
„_
8
Range
0- 2
5
9
12
12 +
No Answer
0- 2
5
9
12
12 +
No Answer
0- 2
5
9
12
12 +
No Answer
No. of
Munici-
palities
5
2
3
—
35
_
3
6
2
3
14
—
4
10
3
_
18
Month
Jan.
Feb.
March
April
May
June
July
August
Sept.
Oct.
Nov.
Dec.
Jan.
Feb.
March
April
May
June
July
August
Sept.
Oct.
Nov.
Dec.
Jan.
Feb.
March
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
No. of
Munici-
palities
1
—
5
3
2
—
3
3
2
—
—
—
2
1
4
1
1
1
5
3
—
3
_
-
__
—
1
—
1
9
—
—
1
_
—
39
-------
TABLE 19 (Continued)
Region
Southwest
West
Canada
Annual Ra
Range
0- 20
40
70
100
100+
No Answer
0- 20
40
70
100
100+
No Answer
0- 20
40
70
100
100+
No Answer
infall (ln.)|Max. Monthly
No. of
Munici-
palities
7
15
2
—
—
1
38
11
5
1
1
3
7
7
2
1
—
4
Range
0- 2
5
9
12
12+
No Answer
0- 2
5
9
12
12+
No Answer
0- 2
5
9
12
12+
No Answer
Rainfall (In.)
No. of
Munici-
palities
5
5
1
1
13
6
5
7
6
4
31
1
2
3
_
—
15
.When Max.
Month
Jan.
Feb.
March
April
May
June
July
August
Sept.
Oct.
Nov.
Dec.
Jan.
Feb.
March
April
May
June
July
August
Sept.
Oct.
Nov.
Dec.
Jan.
Feb.
March
April
May
June
July
August
Sept.
Oct.
Nov.
Dec.
Rainfall Occurs
No. of
Munici-
palities
1
3
—
2
—
_
—
1
13
3
—
—
-
3
1
—
—
1
4
_
.
1
6
1
^
_
_,
1
—
40
-------
East
South
Midwest
Southwest
West
Canada
31
14
22
12
41
10
Rock
19
6
10
16
23
5
No
Answer
7
1
0
0
3
0
TABLE 20
NATIONAL STATISTICAL SURVEY
SOIL CONDITIONS AT SEWER LOCATIONS
Number of Agencies Reporting Each Soil Type
Region Sandy Clayey
35
20
30
22
46
15
Total 130 168 79 11
and in determining correctives for infiltration into old
sewer lines.
Importance of Infiltration Control in Existing
Systems
The national study endeavored to ascertain the
views of officials as to the importance of the
infiltration problem in existing systems. The thinking
behind this phase of the survey was that infiltration
conditions will not be detected or corrected unless
local and state officials are aware of either the
problem's existence or the way it is affecting the
capacities of sewers, pumping stations, treatment
plants, combined sewer overflow facilities, and water
pollution conditions.
To provide this pulse-taking information from
local and state officials and consulting engineers,
many inquiries were made concerning the
importance, causes, and effects of infiltration.
Officials were asked whether they considered
infiltration very important, of average importance, or
of minimum importance. The significance of this line
of questioning readily is understandable because the
responses would signify to what degree these officials
desire to take corrective action.
Table 21, National Statistical Survey - Opinions
of Local Officials On Importance of Infiltration
Problem, summarizes the views expressed.
It shows that 109 municipalities regarded
infiltration as very important; 55 jurisdictions
regarded it as having average importance, and 22,
minimum importance. Among population groupings,
the 200,000-and-over group totaled the highest
percentage of responses in the minimum importance
classification, although the responses in the very
important classification exceeded these by better
than 3 to 1. However, in all other population
categories this ratio was 5 to 1 or greater. A similar
regional comparison between "very important" to
"minimum importance" revealed that the East, West,
and Southwest were all close to a 5 to 1 ratio while
the South and Midwest showed 13 to 1 and 16 to 1,
respectively. Surprisingly, seven jurisdictions in
Canada classed infiltration as very important while
five gave it minimum importance.
These statistics reveal that although infiltration
control's high level of importance generally is
recognized throughout the United States and Canada,
there are variations within regions and population
groups. It might be expected that the high population
cities would express less concern over the infiltration
problem, since many of their systems still use
combined sewers where infiltration during high
intensity rainfall is less of a factor in the total
sewer-flow increase. The East's slightly lower level of
interest may be attributable to the use of combined
sewers. Despite the impact of infiltration on these
systems, the effects are less serious than in separate
sanitary sewers which have lesser capacities and no
provisions for storm overflows.
In addition to municipalities, all the states and
provinces were asked similar questions. Infiltration
was reported to be a problem of importance in 48
states and five provinces.
Also indicating the importance was the response
of more than 70 percent of the consulting engineering
firms participating in the survey covering their
experiences and practices. Retention of consulting
firms to carry out infiltration surveys was reported by
approximately two-thirds of the respondents. Almost
as many of the firms reported they also were retained
to design and supervise actions to correct excessive
infiltration. This is a clear indication that jurisdictions
now consider control of infiltration as a necessary
action in sewerage system maintenance and
operation.
Sources of Excessive Infiltration in Existing Systems
Modern methods of locating and correcting
infiltration sources offer sewer officials opportunities
that previously were unavailable. They provide the
added benefit of economy of investigation and ease
of corrective actions.
In recent years, closed circuit TV inspections and
still photographic inspections have come into
common usage in many parts of the country. Where
41
-------
TABLE 21
NATIONAL STATISTICAL SURVEY
OPINION OF LOCAL OFFICIALS
Population
Region
East
South
Midwest
Southwest
West
Canada
Totals
200,000+
Importance
Very Av. Min. N.A.
4
7
1
3
3
2
3
1
2
2
3
1
2
1
2
1
100,000-
199,999
Importance
Very Av. Min. N.A.
5
6
3
1
4
2 - -
3 - -
1 - -
22-
11-
20,000-
99,999
Importance
Very Av. Min. N.A.
13
4
11
6
19
4
4 3
5 1
4 1
2 1
6 4
4
1
1
2 -
20 11
19 93-
57 25 12
Population
Region
East
South
Midwest
Southwest
West
Canada
Totals
10,000-
19,999
Importance
Very Av. Min. N.A.
3
2
3
2
6
1
2
3
3
1
3
1
1
1 1
2
Under
10,000
Importance
Very Av. Min. N.A.
17 11
2
-1-1
3 - - -
2 - - -
6 3-1
Totals
Importance
Very Av. Min. N.A.
26
19
18
12
35
9
11 4
8 1
14 3
7 3
14 8
5
3
2
7 -
119 59 26 9
TV systems are employed, they sometimes are used as
a routine initial method for locating points of damage
and infiltration in both new and old sewer lines.
Previous sections of this report have delineated
some of the sources of infiltration prevailing
throughout the United States and Canada. Some of
those reported include:
1. Infiltration through sewer joints;
2. Infiltration through sewer cracks;
3. Infiltration into manholes;
4. Infiltration through building sewers and
joints; and
5. Infiltration through connections of building
sewers with street sewers.
Thus, there are three basic sources of infiltration:
(1) Street sewers, (2) building sewers, and (3)
manholes and appurtenant chambers.
The mere presence of defective sewer structures,
however, does not presuppose that infiltration water
will penetrate into these lines. The second ingredient
of infiltration is water. There must be water, plus
points of entry, for infiltration to occur.
The national statistical survey explored the
sources of infiltration in respondent jurisdictions, and
attempted to affix specific percentage estimates of
the total sewer-system infiltration attributable to
these sources. The data were collated in the following
categories: 0-15 percent, 16-30 percent, 31-45
42
-------
percent, 46-60 percent, 61-75 percent, 76-90 percent,
and 91-100 percent. Opinions on sources of
infiltration and their percentage importance in
relation to the total extraneous water volumes in
sewer systems are summarized in Table 22, National
Statistical Survey - Reported Sources of Excessive
Infiltration.
The tabulation data demonstrate that the most
prominent source of infiltration, listed by the greatest
number of jurisdictions, is through defective joints.
TABLE 22
NATIONAL STATISTICAL SURVEY
REPORTED SOURCES OF EXCESSIVE INFILTRATION
Population
Sources
Through Joints
Through Cracks
Into Manholes
200,000+
0-15% 16-30% 31-45% 46-60% 61-75% 76-90%
2141
7
19
14
91-100%
5
1
2
Through Joints 8 2
Through Cracks 14 5
Into Manholes 15 3
100,000-199,999
1 5
1 1
20,000-99,999
Through Joints 20 14
Through Cracks 39 13
Into Manholes 45 5
Through Joints 8 2
Through Cracks 13 4
Into Manholes 12 3
12
4
3
2
10
1
1
10,000-19,999
3
Through Joints
Through Cracks
Into Manholes
1
5
5
Under 10,000
Through Joints 44 24 19
Through Cracks 90 24 4
Into Manholes 91 14 4
Total
19
1
2
11
43
-------
The officials gave varying estimates of the relative
importance the entry of extraneous water via this
type of defect. No other source of infiltration was
cited as consistently; it was reported in all areas of
the United States and in Canada.
Defective sewer barrels and defective manholes
also were listed as sources of excessive infiltration,
but in general they were classified as of relatively
lesser significance — in the 0-15 percent category. In
the case of infiltration through joints, a number of
jurisdictions, particularly in the 20,000 to 99,999
population category, attributed to this source as
much as 61 to 75 percent of the total ground water
entry into sewerage systems.
It should be pointed out that this inquiry covered
not only infiltration conditions but the sources of
inflow into sewer systems and the relative importance
of these inflow points. This information on inflow is
summarized and evaluated in Section 5 of this report.
Causes of Excessive Infiltration
In Existing Systems
The survey of state and provincial water
pollution control agencies explored the agencies'
opinions on infiltration sources in their regions. Poor
joints in Old sewer systems were the most frequently
listed source. This condition was reported by 24
states. Paralleling it were such reported causes as poor
construction, poor inspection, poor maintenance, and
shifting of old sewer lines due to poor soil conditions
and unsatisfactory backfill methods.
In the United States other causes of infiltration
were listed as usage of low strength pipe, poorly
installed building sewers, illicit connections, and high
ground water tables. High ground water table
conditions were listed by eight states as the cause of
infiltration.
In Canada, poor joints, illicit house connections,
poor house sewer caps, and poor construction were
listed as causes. Poor joints and high ground water
tables were so listed in three provinces.
Effects of Excessive Infiltration
In Existing Systems
In the data resulting from the survey of state and
provincial water pollution control officials, it was
revealed that infiltration causes the overload of waste
water treatment plants in 50 percent of the states and
provinces. The next most widespread effect was
reported to be overloaded sewers and local basement
flooding. By-passing of flows to allay surcharged
sewers, local flooding, and plant overloading were
reported by 13 states. Increased cost of treatment
was reported by five states, and interference with
treatment efficiency by three. Other effects were
reported as damaged sewers, increased pollution
conditions in receiving waters, and shortened design
life of sewage works facilities.
In Canada, overloaded sewage treatment plants
and surcharged sewers were the predominant effects
of infiltration, in the opinion of provincial water
pollution control agencies. Other adverse conditions
were listed as early obsolescence of facilities,
upsetting of lagoon treatment systems, and excessive
overflows to streams.
The national municipal statistical survey revealed
that infiltration caused sewer surcharges and local
flooding, overloading of sewage pumping stations,
excessive overflows of combined sewers, and
treatment plant overloading and by-passing.
Treatment process problems reportedly have resulted
from excessive flows of storm water. In the
over-200,000 population category, the greatest effect
of infiltration was reported to be sewer surcharging
and local flooding. In the 100,000-to-199,999 range,
it was pumping station overflows. In the
20,000-to-99,999 range it was waste water treatment
plant overloading. In the 10,000-to-19,999 group,
reports of overloading and treatment plant operation
problems predominated. In the under 10,000 range,
combined sewer overflows were most frequently
cited.
Overall, sewer surcharging and flooding led the
list of reported difficulties, with more than 50
percent of the problems attributable to this
condition. Pumping station overloads were almost
equally prevalent — again, with 50 percent of the
jurisdictions reporting this condition. Waste water
treatment plant problems, due both to overtaxing of
capacities and adverse process effects, were reported
in 58 of the 66 replies from respondent
jurisdictions — or almost 90 percent of the total
participants in this phase of the national survey.
Benefits of Correction
Of Existing Infiltration
The predominating benefit cited by consulting
engineers was the reduction in wastewater
treatmentplant costs. In 10 cases, this was reported as
the most tangible and measureable benefit of
infiltration control. Improved operation of plant
units and sludge digestion facilities were cited.
Postponement of plant enlargement was attributed to
infiltration control in the case of one jurisdiction.
Elimination of sewer surcharge and basement
flooding and property damage frequently were
44
-------
reported. Regained sewer capacity after infiltration
control was reported by six respondent consulting
firms.
Other benefits cited by these firms included
elimination of salt water intrusion into sewerage
systems, reduced sewer maintenance costs, and
correction of harbor pollution through control of
combined sewer overflows or sewer system
by-passing.
One consultant said corrections were not
instituted because of "political complications." Three
noted that in some jurisdictions corrections were too
costly for the benefits derived. But it is significant
that in most cases consulting engineers said benefits
were sufficient to compensate for the cost of
infiltration control. Ten times as many reported
positive economic benefits as reported costs
outweighing the benefits.
Officials of jurisdictions in the national statistical
survey were asked to express their views on the
potential benefits of infiltration control measures.
Specifically they were asked about lower pumping
costs, improved treatment plant operation, reduced
stream pollution, reduced system repairs, reduced
sewer surcharging and flooding conditions,
elimination of immediate need for new sewer
construction, and miscellaneous benefits. In all
regions of the United States, and in all population
size ranges, officials were of the opinion that control
measures could achieve one or more of the listed
benefits. However, the affirmative evaluations were
distinctly lower in the communities below 10,000
population.
In Canada, the only population group expressing
affirmative views on all the tabulated benefits was in
the 20,000- to 99,999- population range. In the other
size groupings, little benefit was seen as resulting in
any of the categories except lower pumping
requirements and improved treatment plant
operation.
A similar proportion of affirmative reactions was
shown in the under-10,000 population grouping of
the United States in the East, South, Southwest, and
West. The Midwest differed from the other areas in
this respect; opinions were affirmative on all the
listed potential benefits.
The greatest number of affirmative responses was
in the 20,000-to-99,999 population grouping, just as
it was for the survey of the relative importance of
infiltration control.
This phase of the national municipal statistical
survey indicated that sewer system officials believe
specific benefits can be derived from infiltration
control measures.
Methods of Detection of
Existing Infiltration Sources
Several techniques were reported by surveyed
jurisdictions for use in locating sources of infiltration
in existing sewer systems:
Infiltration flow measurement with weirs,
flumes, or other flow measuring devices
usually are made at off-peak hours and
during dry and wet-weather conditions to
determine the variations attributable to
infiltration. In an old system, inflow may
account for part of this excess flow and it
cannot be distinguished from infiltration.
However, if excessive flows do not
appreciably increase immediately after
rainfall and runoff, they can be considered
infiltration. If the flow increases markedly
within an hour or so after the beginning of
an intense rain, inflow from roof leaders,
drains, and sump pumps can be suspected.
For many investigations actual flow may not
need to be measured. Instead correlations are
developed as to inches of flow during dry
weather, wet weather and rainfall
simulations. Depth of flow within the sewer
may be more economical to determine, and
if needed can be corrected to flow by
appropriate calculations.
Ground water level measuring devices in
manholes — in the form of a tube inserted
through the manhole wall, with a gage
utilizing a clear plastic tube placed along the
manhole wall (head checkers) — can assist in
evaluating the extent of sewer immersion in
ground water.
Smoke Testing can at times indicate poor
joints and cracked pipe by showing up on the
ground surface near the leak. If the ground
water table is above the pipe, the smoke may
be lost in the water. Smoke can also indicate
illicit connections by appearing inside,
outside, or at the roof line of a house or
other structure or in cross connected
facilities.
Television Inspection, with a closed circuit
camera pulled through the suspected pipe,
can disclose defective sections and actual
infiltration flows when a high ground water
condition exists. Amounts of infiltration can
be roughly approximated and the condition
can be recorded by video tape or Polaroid
cameras. TV systems are constantly being
refined to reduce the size of equipment,
increase the clarity, color and depth of
45
-------
FIGURES
Courtesy: Penetryn System, Inc.
INFILTRATION AT OFFSET JOINT
image, and reduce operating costs.
Some advantages of TV inspection include
immediacy of observation, ability to detect
movement of waters, ability to observe
changes in flow, and the advantage of moving
back to recheck or watch repair operations.
Photographic Inspection methods are being
used to permit taking photographs of sewer
interiors. Although photography is applicable
to inspection of new construction, it also can
be used to obtain clear and interpretable
pictures of existing defective sewers. For
permanent records it is economical and
convenient, but it cannot provide the
intimate and immediate knowledge that TV
inspections afford. A combination of the two
techniques may be feasible.
Figure 6 Infiltration at Offset Joint, is a
photograph of infiltration occurring at a
defective joint. Sealing equipment is shown
behind the joint, waiting to be used. Figure
7, Improperly Installed Sewer Connection, is
a photograph of an 8-inch sewer. The
building sewer intruding into the sewer may
leak and will impede cleaning. Figure 8 ,
Broken Joint, is a photograph of a broken
joint on a 12-inch pipe. Although not leaking
at the time of inspection, infiltration can be
expected.
Bottle Gauges and more sophisticated devices
are used to indicate the degree of surcharging
in a manhole. Such devices either float and
indicate the highest water level attained in
the manhole or they collect samples at
various points to show the peak level
experienced in the chamber. New
developments in telemetering and stop-action
photography also can be used to photograph
or transmit sewage level measurements
behind weirs, to augment liquid level
registration-recording data.
Rainfall Simulation Tests sometimes are used
to detect cross-connections and leaks
between storm and sanitary sewers by
flooding adjacent storm sewer sections and
checking for the appearance of dyed water in
a sanitary system.
Comprehensive Planning for Infiltration
and Inflow Control
Prior to the design of sewer system extensions or
wastewater treatment plant facilities, comprehensive
46
-------
FIGURE?
Courtesy: Pcnetryn System. Inc.
IMPROPERLY INSTALLED SEWER CONNECTION
FIGURES
Courtesy: Penetryn System, Inc.
BROKEN JOINT
47
-------
planning is needed to ensure that an economical
facility will be constructed. The planning stage may
require two years to complete in order that all
pertinent information may be gathered and analyzed.
The cost of this planning is generally only a small
portion of the construction cost.
A comprehensive investigation of infiltration and
inflow will involve ground water studies, roof drain
checks, flooding of storm sewers, sewer surveys,
analysis of flow charts and lift station records, sewer
cleaning and inspection, followed by intensive
interpretation and evaluation.
Funds for Comprehensive Planning
The cost of the type of comprehensive planning
described was not contemplated when existing
consulting engineer fee schedules were prepared. A
consultant cannot be expected to prepare an analysis
of infiltration and inflow conditions at the same
percentage rate as would be charged under a
"reasonable curve" as typified by the ASCE C
schedule. An additional difficulty at this time is that
construction grants from most federal and state
agencies do not consider such comprehensive
planning eligible for inclusion in the allowable costs.
The Federal Water Quality Administration does not
have planning money available. The Federal Housing
Administration has limited planning money but it has
not been made sufficiently available for studies of
infiltration and inflow control. The Department of
Housing and Urban Development does not have a
clear mechanism for including planning funds in a
construction grant request. This lack of funds for
planning is a paradox as both the local agency and the
grant awarding agency could benefit from reduced
construction costs if infiltration and inflow
conditions were remedied. Local agencies who receive
construction grants are usually those which are not
able to adequately fund such planning on their own
and thus only a minumum of planning is performed
prior to design of such facilities.
A Suggested Plan of Action
The Sub-Committee on Sewer Service and
Maintenance of the Industrial Advisory Panel, created
by APWA as a part of its investigation provided
important information for evaluation by the project
staff. Taking up the question of infiltration surveys,
evaluation of the extent of infiltration, and methods
of restoring sewer lines to infiltration-free condition,
a memorandum was prepared by one of the
engineering support organizations represented on this
subcommittee. A brief outline of a 10-stage program
for analysis and restoration of sewer systems is
included as a portion of this report because it
demonstrates the logical step-by-step procedures
which may be of service to municipalities for the
location and correction of excessive infiltration. (A
more complete exposition on a multi-phase
pre-cleaning-survey-evaluation-correction program of
infiltration control is contained in the Manual of
Practice.)
A TEN-STAGE PROGRAM FOR
INFILTRATION ANALYSIS AND THE
RESTORATION OF SEWER SYSTEMS
Stage One - Set Objectives.
A. The first problem is to find the problem.
B. Determine the need for a sewer system
analysis and establish a systematic sewer
maintenance program.
Stage Two - Develop a Workable Plot Plan of the
Sanitary and Storm Sewer Systems.
Stage Three - Identify the Scope of the Infiltration:
A. Place ground water level gauges in manholes.
B. Install recording devices at lift stations in
metering stations.
C. Survey the presence and extent of inflow.
Stage Four — Make a Rainfall Simulation Study.
Stage Five — Determine the Extent of Pre-cleaning
Needed to Produce Optimum Results from TV or
Photographic Inspection in the Isolated Trouble
Sections of the System.
Stage Six — Make an Economic and Feasibility
Study.
Stage Seven — Carry Our Necessary Initial Cleaning.
Stage Eight - Make Television Inspections.
Stage Nine — Restore and Repair System.
A. Structural deficiencies.
B. Infiltration.
Stage Ten - Establsih Treatment Plant Design
Criteria.
The foregoing procedure outlines an extensive
and logically oriented program for the determination
and correction of infiltration and inflow conditions.
48
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Plans for Future Corrective Action
The national statistical survey attempted to
ascertain whether or, not representative jurisdictions
in the United States and Canada intend to carry out
precorrective surveys of infiltration conditions in
their sewer systems; whether such surveys will be
followed by actual corrective actions, where needed
or indicated; and whether budgetary funds have been
or will be allocated for such work. The survey data
obtained in response to these inquiries are contained
in Table 23, National Municipal Statistical
Survey — Future Corrective Action in Infiltration
Control.
The survey information indicated that more
jurisdictions than not are planning to carry out
infiltration surveys. A number could give no clear
information on this question because of budgetary
and administration problems.
The large number of communities not
contemplating such surveys can be attributed either
to their not giving this matter sufficient thought and
attention, the absence of problems severe enough to
warrant any such survey efforts, or possibly not
knowing where to begin analyzing the problem. In
the Southwest this large percentage may indicate such
work is unnecessary because of low precipitation, low
ground water tables and, consequently, the limited
amount of infiltration experienced in this relatively
dry region.
Although a great many of the responding
jurisdictions did not plan infiltration surveys, a large
percentage reported actual plans for corrective
actions. Thus, in spite of the lack of full-scale
infiltration surveys, most communities realize there
are places within their systems that require
correction, and they are planning programs to reduce
or eliminate such excessive flows. A further
discussion of the costs and economic factors involved
in infiltration and its control will be found-in Section
8 of this report.
Method of Correction of Existing Sewer Infiltration
After the economic and practical feasibility of
correcting sewer infiltration has been determined,
there are three basic approaches: (1) replace the
defective component, (2) seal the existing openings,
and (3) build within the existing component.
Replacing sections of sewers found to be
damaged is, at times, the only alternative. However, it
may be the most expensive method of correction and
the most disruptive to the local environment and
public convenience. For this reason, if the problem
appears to be one of open joints or pipe cracks and
the pipe itself is structurally sound, there are
alternative methods of repair without excavating and
replacing the sewer line. If the sewer pipes are of a
large diameter, such as in large interceptor trunk
systems, they may be sealed either by machine lining
or manual lining of joints. Figure 9, Manually Lined
Joints, is a photograph of steel banded joints to
reduce infiltration.
Large diameter pipes, even when theyre
structurally damaged, may be repaired by plastic
liners within the pipes. This has been accomplished
with reported success in Toronto, Canada, where the
Commissioner of Public Works has developed a
special technique for installing plastic liners. Recently
developed reinforced plastic mortar pipes also have
been utilized in some sections of the country for
lining large diameter sewer lines. Figure 10,
Installation of Pipe Liner, shows a fiberglass pipe liner
being inserted into a deteriorated pipe. The smooth
inside surface of the liner may allow the same flow to
be carried as in the larger original pipe.
House sewers may be repaired by replacement
since these may be too small for use of internal
grouting techniques. However, external chemical
grouting has been used for this purpose.
A common method of sealing leaks involves the
introduction of chemical compounds which, in
contact with the soils surrounding the defective
points in sewer lines, from a "cast" or "bandage"
around the pipe. This method of sealing has produced
some excellent results when used for application
under pressure from inside of sewer lines, whence it
extrudes to the outside of the pipe and into the pores
of the surrounding soil. The introduction of
congealing chemical gels also has been made into the
soil by direct injection from the surfact at the points
where infiltration has been detected by a television
camera inspection or other means. Figure 11, Internal
Grouting Equipment, shows equipment in place for
the purpose of sealing a joint. The first photograph
shows the "train" of the TV equipment and. the
packer in a deflated position. The television camera is
used to align the position of packer and to check the
condition of the joint after sealing. The second
photograph shows the packer in an inflated position
ready for sealing. The packer is hollow, generally
allowing wastes in existing sewers to continue to flow
without disruption.
The Federal Water Quality Administration, U.S.
Department of the Interior, has issued a report on
"Improved Sealants for Infiltration Control." It
covers the development and demonstration of
materials to reduce or eliminate water infiltration
49
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FIGURE 9
.
Rfl
Courtesy: Armco Steel Company
MANUALLY LINED JOINTS
50
-------
FIGURE 10
Courtesy: United Technology Center
INSTALLATION OF PIPE LINER
51
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into sewer systems. The objective of this research
program was to develop new and more effective
sealants for sewer line leaks, investigate all equipment
and materials required for such work, and test and
compare various materials on the basis of
effectiveness and economy. The study illustrates
current interest in infiltration control and the need
for continuing research and development of effective
grouting or sealing materials to repair defective
conduits and joints.
The major emphasis of this section has been on
infiltration. Methods for inflow analysis are discussed
more fully in Section 5 of this report.
TABLE 23
NATIONAL STATISTICAL SURVEY
FUTURE CORRECTIVE ACTION ON INFILTRATION CONTROL
POPULATION
Will city conduct
Infiltration Survey
Will defective
sewers be sealed
or replaced
POPULATION
will city conduct
Infiltration Survey
Will defective
sewers be sealed
or replaced
200.000
Yes No NA
21 14 4
32
5
10,000-
19,999
Yes No NA
2 10 12
22
100,000-
199,999
Yes No NA
14 12 5
24 3 4
Under
10.000
Yes No NA
4 5 1
20,000-
99,999
Yes No NA
43 34 22
75
8 16
Totals
Yes No NA
94 75 44
141 18 37
FIGURE 11
INTERNAL GROUTING EQUIPMENT
52
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SECTION 5
THE INFLOW PROBLEM
This project was planned and executed to
distinguish between infiltration water and inflow
water, in order to evaluate these dual causes of
extraneous water flows in sewer systems, their
effects, and means of correction. True, infiltration
and inflow have the same general effect of impairing
the ability of sewer systems, combined sewer
regulator-overflow facilities, pumping stations and
treatment plants, to render the service for which they
were designed, constructed and operated. However,
their specific causes may be different, and the means
of correction are entirely different.
It obviously is desirable, therefore, to consider
these two components of extraneous entry waters
separately, wherever this is possible, and examine
them as two separate problems. This has been done
for this research study. (The problem of infiltration
has been covered in Section 4 of this report.)
The distinction between the "Two I's" was
delineated in Section 2 of this report. To clarify the
following discussion of the inflow problem and the
data obtained on national practices, policies, and
performance during the course of the investigations,
the definition of inflow is again stated:
"Inflow covers the volume of any kind 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 as
previously defined." (As covered in Section 4
of this report.)
Sources of Inflow
The definition spells out the basic sources of
inflow into sewer systems. Such sources of inflow
generally are related to private buildings and private
land areas. They usually represent a deliberate
connection of a drain line to a public sewer system.
These connections may be authorized and
permitted; or they may be illicit connections made
for the convenience of property owners and for the
solution of on-property problems, without
consideration of their effects on public sewer
systems.
If permitted by sewer, plumbing, or housing
codes, these connections are deliberately made and
the discharges to the sewer system are, at least in
theory, provided for in sewer design. Obviously, in
many instances, the removal of such extraneous water
from properties and buildings is essential for
protection of the living environment and preservation
of the value of the properties involved. However, the
trend is toward permitting such connections to storm
sewer or combined sewer systems, rather than to
building sewer lines discharging into separate sanitary
sewers.
Even this generalization is not justified under all
circumstances. Some sewer authorities favor the
connection of cellar or sump drains to sanitary
sewers, on the basis that the waste water originating
in such drain lines will contain laundry wastes,
basement wash water, and other liquids which,
appropriately, should be carried by sanitary sewers.
Roof leaders fall into a different category. Despite
the fact that such drainage water often contains
particulate wastes stemming from atmospheric
pollution sources, bird droppings, rodent wastes, and
other debris, many authorities advocate the discharge
of roof water into street gutter areas — or onto on-lot
areas in the hope that it will seep into the soil by
percolation.
Building sewer connections may carry such
extraneous inflow waters, and infiltration waters too,
where the lines are poorly constructed or have
become defective during years of service. However,
the inflow factor must not be confused with the
infiltration problem in building sewers, as briefly
discussed in Section 4 and more fully evaluated in
Section 7.
Industrial-Commercial "Clean Waters"
The problem of inflow volumes having their
sources in commercial and industrial operations is
separate and apart from the roof leader and basement
and foundation drain lines. Of course, commercial
and industrial buildings have similar drain connection
problems, and the roof drainage volumes discharged
from large flat and semi-flat roof surfaces of large
structures are even more extensive than from homes
and other smaller buildings. But the inflow problem
to which this discussion refers is the result of actual
in-structure operations. The inflows from these
sources include so-called clean waters from on-stream
operations, cooling waters, and other related
functions. They can represent relatively large volumes
of water that could seriously affect the carrying
53
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capacity of sanitary sewers, if such connections are
made in accordance with local rules or ordinances, or
in violation of regulations prohibiting such discharges.
It is difficult to rationalize hard and firm reasons
for permitting or prohibiting such inflows into sewer
systems. If such waste waters are deemed pollutional
in nature, there may be justification for authorizing
their discharge into sanitary or combined sewer lines.
If, however, they are of the "clean" nature indicated
in this project's definition of inflow waters, discharge
into sanitary and even combined sewers may be
highly undesirable. Disposal of such waste waters may
be necessary to the proper and effective use of
commercial-industrial properties and essential to
on-stream operations in such installations; in such
cases their discharge into storm sewers or combined
sewers may be required.
It may be reasoned that a municipal jurisdiction
must provide for some form of legitimate collection
and transportation of such unavoidable waste waters.
This is why the principle of re-use of on-stream
waters is attracting wide attention. Reclamation and
re-use of such waters as clean cooling waters can
greatly reduce (1) the volumes of inflow waters which
must be carried by public sewers and (2) the water
supply demands. It is obvious that designers and
operators of sewer facilities should explore this trend.
Nature of Inflow Waters
It is necessary to draw a quality comparison
between infiltration waters and inflow waters. The
former liquids, in the main, have not been directly
exposed to man-made environmental conditions;
essentially, their source is ground water resulting
from precipitation conditions. In the absence of
ground water juxtaposed to sewer conduits,
infiltration is not a problem. Inflow waters, as
outlined above, have been more directly exposed to
the environment and carry environment-induced or
man-produced contaminants.
To some extent, this variance in sources results in
some differences in quality of the "Two Fs," but the
two types of extraneous water which intrude into
sewers do not differ significantly in quality, except
for the pollutants unavoidably or deliberately intro-
duced into inflow waters by commercial-industrial
operations. Foundation inflow, for example, does not
vary greatly from the kind of water which infiltrates
sewer lines from ground water sources. Basement
drainage may carry wastes and debris originating in
homes, including laundry waste water.
Effects of Inflow
"Volume" is the most important characteristic of
inflow waters, just as it is of infiltration waters. While
the former waters contain suspended and dissolved
pollutional constituents, and while infiltration carries
sand and silt entering sewer systems with the ground
water, these are not usually predominating factors in
the operation and performance of sewer systems and
pumping and treatment facilities. The amount of
inflow waters which rob sewers and sewage-handling
installations of essential capacities produce the same
kind of effects as excessive volumes of infiltration.
Some minor differences in the effects of the
"Two Fs" are worthy of note. Inflows do not cause
the clogging of sewers with sand, gravel, and other
soil debris entering sewers with infiltration water.
Inflows do not induce the growth of tree roots that
intrude into sewer barrels through the same defective
joints and pipe cracks and breaks that permit the
infiltration of ground water.
Except for these variations between inflow and
infiltration effects, the conditions outlined in Section
2 prevail for both extraneous water phenomena. The
effects of excessive inflow waters include:
Flooding of local sewer lines, streets, and
roadways.
Backflooding of connected properties.
Increased cost of pumping and sewage
treatment.
Reduced life of pumping and treatment
units.
Reduced capacity of sewers to handle added
urban developments, foreshortening the life
of sewer systems, and adding to the need for
auxiliary sewer construction.
By-passing of pumping stations and
treatment processes to prevent overloading
and malfunctions.
Excessive overflows from combined sewer
systems at regulator stations.
Need for diversion of flows from sanitary
sewers to adjacent storm sewers or nearby
watercourses, to overcome serious
surcharging of lines receiving excessive inflow
waters.
Correction of Excessive Inflows
Correction of inflow conditions is dependent on
regulatory actions on the part of sewer officials,
rather than on public construction measures. If
inflows are due to unauthorized connections,
54
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correction must be accomplished by surveys which
will disclose the presence of such waters; surveillance
measures which will locate the actual sources, and
action by officials to order the elimination of inflow
connections, followed by inspections to confirm such
removals.
In cases where illicit or unauthorized connections
have been made, officials must examine the
effectiveness of their sewer-use regulations and
evaluate their sewer, plumbing, and building
inspection practices, to determine if these have the
power to prevent improper actions and enforce orders
to eliminate points of inflow. If violations of clear-cut
regulations are found, the effort and cost involved in
their correction should be the responsibility of the
property owner who made, authorized, or inherited
the illicit connections.
In cases where inflow connections were made
with jurisdictional approval, or where no positive
prohibitions against such physical connections have
been included in plumbing, building, or sewer rules
and codes, all or part of the responsibility for making
corrections may devolve upon the jurisdiction itself.
Concern over excessive inflows often may occur
"after "the fact" - after it has been found that the
volumes of flow exceed what had been anticipated
when permissions for inflow connection were issued,
or when local agencies failed to enact inflow
connection prohibitions. If elimination of existing
inflows is deemed necessary because of the adverse
effects of these flows on sewer systems, pumping
stations, treatment plants, or combined sewer
regulator-overflow installations, new or more
restrictive sewer-use regulations may have to be
invoked.
These are the general factors involved in sewer
system inflow. Principles and practices have been
expounded here as a preamble to a detailed review of
the findings emanating from various surveys of the
national study project. Every facet of sewer inflow
was covered by the investigation of causes and
sources of water intrusion, effects of these flows, and
methods used or proposed by jurisdictional officials
to overcome the adverse results of these practices.
Recognition of Inflow Problems
Sixty-seven percent of the consulting engineers
providing information on the problem of inflow
reported that they had been engaged to survey
locations and nature of excessive inflows of various
waste waters into sewers. This response indicated that
the inflow portion of the extraneous water problem is
recognized by most consultants and their clients,
although both infiltration and inflow are
undoubtedly considered as a single volumetric factor.
However, when asked if such investigations resulted
in the elimination of inflows, fewer than 50 percent
replied in the affirmative. This can be interpreted as
meaning that recognition and location of inflow may
be much simpler than the actual elimination.
During the statistical survey, municipalities were
asked if excessive inflow into their sewer systems was
a problem. Table 24, National Statistical Survey - Is
Inflow a Problem?, summarizes the responses by
regions and population groupings.
TABLE 24
NATIONAL STATISTICAL SURVEY
IS INFLOW A PROBLEM?
Region and No
Population Group Yes No Answer
East 37 7 1
South 23 4 1
Midwest 24 9 2
Southwest 22 2 1
West 21 30 2
Canada 18 2 1
200,000+ 25 12 2
100.000-199,999 15 15 1
20,000- 99,999 39 53 7
10,000- 19.999 14 16 4
Under 10,000 361
Total 96 102 15
On a total response basis a greater number of
jurisdictions reported no problem. However,
one-third of the number supplied no information or
indicated that this information was not known.
Among the regions of the United States, only the
Midwest produced more "yes" answers than "no"
answers — by a 3 to 1 margin. As might be expected,
the South and Southwest reported a high ratio of
"no" to "yes" responses. In general, the results
substantiated the in-depth field investigations, finding
that municipalities in warmer climates — where slab
construction of buildings is predominant — do not
experience excessive inflow connections, because of
the absence of basement and roof drains.
Analysis of responses on a population basis
revealed that large cities are much more aware of, and
involved with, the problem than smaller communities.
The 200,000-and-over population group gave twice as
many affirmative answers as negative, while the
55
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under-10,000 group had almost a 4 to 1 ratio of "no"
to "yes" responses. Obviously the larger cities, even
though many still use combined systems,recognize
the impact of inflow connections on the overall
capacity and efficiency of their sewers and treatment
works.
Sources of Inflow
The 66 consulting firms contacted in connection
with the survey of engineering practices gave roof
drains the most frequent mention as a source of
inflow, as indicated in Table 25, Consulting
Engineers' Survey, Sources of Inflow.
It is revealing to find that almost one-third of the
respondent consulting engineering firms offered no
opinions or answers on this subject. In general, these
TABLE 25
CONSULTING ENGINEERS SURVEY
SOURCES OF INFLOW
Sources
Roof Drains
Foundation Drains
Basement or Yard Area Drains
Industrial/Commercial Clean Water
Drainage of Springs/Swamps
Other Various
No Opinion
Number of
Consultants
Reporting
38
34
32
21
20
5
19
Population
Storm Water-
Building Sewer
Storm Water-
Manholes
Ground Water-
Basement Drain
15
10
TABLE 26
NATIONAL STATISTICAL SURVEY
SOURCES OF INFLOW
200,000+
0- 16- 31- 46- 61- 76- 91-
15% 30% 45% 60% 75% 90% 100%
1
2
2
3 - - - -
100,000-199,999
0- 16- 31- 46- 61- 76- 91-
15% 30% 45% 60% 75% 90% 100%
8 4 1 2 - - -
10 7 2 1
10 3 - - 1 -
Population
Storm Water-
Building Sewer 25
Storm Water-
Manholes 32
Ground Water-
Basement Drain 8
20,000-99,999
62 62-
31 421
1 - -
10,000-19,999
54111
12 2 2 - 1
8 1
Storm Water-
Building Sewer
Storm Water-
Manholes
Ground Water-
Basement Drain
5 - -
6 1
3 1
Under 10,000
1
Totals
50 19 5 14 5
61---
53 17 1 31
56
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represent the percentage of consultants who never
have been asked to carry out inflow surveys. The
absence of such assignments can be linked to the fact
that most jurisdictions reported no involvement with
inflow problems.
The 212 jurisdictions surveyed in the United
States and Canada supplied their evaluations of the
percentages of total excess waste water flows due to
specific inflow sources. Table 26, National Statistical
Survey — Major Sources of Inflow, presents a
summary of findings with respect to storm water
entry through building sewers, into manholes, and
ground water intrusion through basement drains. Of
all sources of excess water entering sewer systems,
inflows from four sources were classified as
contributing from 90 to 100 percent of the total
excess flow. A similar tabulation on the infiltration
problem is contained and discussed in Section 4.
Control of Existing Inflow
Referring to restrictions on some specific sources
of inflow, the national statistical survey asked if
connection of downspouts to building sewers was
permitted. Table 27, National Statistical
Survey — Are Downspouts Permitted to be
Connected?, summarizes the replies from the United
States and Canada.
The answers to this question demonstrated an
overwhelming prohibition of inflow connections; the
ratio was almost 10 to 1. Specifically, only 22 out of
212 permit them. As pointed out in subsequent
sections of this report, the direct entry of rain water
from roofs is recognized almost universally as
undesirable.
In contrast, the jurisdictions replied in a
significantly different manner when asked if they
TABLE 27
NATIONAL STATISTICAL SURVEY
ARE DOWNSPOUTS
PERMITTED TO BE CONNECTED?
Region and
Population Group Yes No No Answer
East 9 35 1
South 0 28 0
Midwest 4 31 0
Southwest 0 25 0
West, 4 54 1
Canada 6 15 0
200,000+ 10 28 1
100,000-199,999 0 31 0
20,000- 99,999 8 91 0
10,000- 19,999 4 29 1
Under 10,000 1 9 1
Total 23 188 2
permitted the connection of basement, foundation,
or other drains to building sewers. Table 28, National
Statistical Survey — Are Basement Drains Permitted
to Be Connected?, summarizes these results on a
regional and population basis.
The total replies indicate a 2 to 1 ratio between
prohibitions of basement drain connections and
acceptance of such inflow waters into sewer systems
as against 10 to 1 in the case of roof leader
prohibitions. Policy approving basement drains, as
noted in other investigations, results from the basic
assumption that they may contain waste waters
requiring treatment.
TABLE 28
NATIONAL STATISTICAL SURVEY
ARE BASEMENT DRAINS PERMITTED
TO BE CONNECTED?
Region and
Population Group Yes No No Answer
East 25 19 1
South 4 23 1
Midwest 10 25 0
Southwest 5 19 1
West 16 42 1
Canada 17 4 0
200,000 +
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Total
Yes
18
12
32
10
5
77
No
20
19
65
23
5
132
No Answer
1
0
2
1
0
57
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Regionally, only the eastern part of the United
States and Canada revealed a majority of jurisdictions
permitting basement drain connections. The
predominance of old systems and old connections in
that part of the United States mitigates against strict
sewer-use regulations and enforcement. Not a single
population ca-tegory reported a majority of
jurisdictions permitting this practice.
Connection of Cellar, Foundation and Roof Drains
The 26 jurisdictions visited by staff investigators
were asked if roof leaders, cellar drains, and
foundation drains were permitted to be connected to
sanitary or combined sewers. No jurisdiction permits
roof leaders to be joined to sanitary sewers. However,
10 permit such connections to combined sewers; only
two communities do not permit such connections.
Three members of the Advisory Committee reported
permission for drain connections to sanitary sewers;
10 jurisdictions permit these connections to
combined sewers. The connection most frequently
permitted was reported to be the cellar drain. Six of
the 26 jurisdictions permit cellar drains to be
connected to the sanitary sewer, and nine permit
connections to their combined sewers.
An evaluation of these responses indicates that
roof leaders obviously are recognized as the greatest
contributors of storm water drainage to sanitary
sewers, and jurisdictions deem this connection
undesirable. Foundation drain connections are permit-
ted by a small percentage of jurisdictions, probably
because such drains are a requisite for certain private
mortgage money and Federal housing grants. In the
absence of an available storm sewer system,
foundation drains must be connected somewhere and
the sanitary sewer often is the most convenient
recipient of these inflow waters. Connection of cellar
drains is permitted more often because these are not
considered an obvious interconnection of ground or
storm water into sanitary sewers. However, it is quite
obvious that if basement flooding results from
intensive rainfall or any other condition of high
ground water table, it will be alleviated through the
basement drain or the cellar drain directly into the
sanitary sewer. Cellar-drains, therefore, are an indirect
source of ground water inflow.
One jurisdiction made the following comments
on the connection of roof, cellar, and foundation
drains: "Roof drainage, cellar drains, and foundation
drain connections to combined sewers only, are
permitted where no storm sewer exists. However, we
ask the owners of commercial buildings to provide a
separate soil pipeline for such drainage at least out
beyond the building wall, where it is tied in with the
sanitary pipe. This has the advantage of minimizing
the effects of a stoppage in the sanitary soil pipe
within the building during storm conditions and it
also permits comparatively easy laying of a separate
storm drain to the street at any time a street storm
sewer is provided."
The Metropolitan Sanitary District of Greater
Chicago requires a statement (on all plans for building
sewer connections) to the effect that downspouts and
foundation drains will discharge into the ground. If
this is contrary to local ordinances, the specific
reference and the local ordinance must be submitted.
The District also stated that no communities
discharging into the District System may authorize
the discharge of storm water into a sanitary sewer.
One respondent stated that in his jurisdiction it is
unlawful to connect roof drains and foundation
drains to the sanitary sewer system but that cellar
drains may be connected to the sanitary system. He
reported: "We consider these floor drains to be
primarily for waste water used in cleaning within the
building." This is the usual line of reasoning when
connection of interior floor drains is permitted, but
these drain connections can be seriously abused in
practice.
The Areaway Drainage Problem
The in-depth investigations of the 26
representative jurisdictions visited by project
representatives brought to light the special problem
of draining cellar areaways. In some sections of the
country, particularly in areas of Maryland, Delaware,
and Virginia, part of the traditional construction of
the old housing in the cities included these uncovered
basement entries. In some jurisdictions, up to 30
square feet of uncovered areaway is permitted to be
connected to the sanitary sewer within the house.
Some years ago a number of major cities in the region
prohibited such connections but soon found that
plumbers or contractors of new homes were illegally
making them beneath the basement floor into the
floor drain piping. One jurisdiction which conducted
an inspection program to expose these connections
by visual and manual means reported that steps to
enforce removal of such connections eventually were
stopped because of homeowner opposition and the
objection of local legislators.
As the survey progressed farther into the South,
connections of this type were found to be only a
minor problem, since many of the homes do not have
basements and the roof drainage is allowed to spread
out on the surrounding land. In areas where inflow
sources are of little significance, jurisdictions find it
much easier to detect infiltration because it is not
58
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confused with inflow.
As for the connection of storm and ground water
through the house sewer, the Advisory Committee
was asked if there were many illicit or illegal
connections despite local prohibitions. Seventeen
reported that such surreptitious entries frequently are
encountered. Seven reported none. This response,
while initially unexplained, has been found to have
validity, especially in areas where connection of such
drains is not necessary because of slab-type
construction and the absence of basement and
foundation drains. Twenty-one jurisdictions reported
they have sewer-use ordinances to regulate the
discharge of waste water into sewer systems. Four
reported that no such regulations are in use. Among
those answering that a sewer-use ordinance is
invoked, a number said provision is contained in a
plumbing code. Plumbing codes, in many cases, are
not completely equivalent to an ordinance. These
findings indicate there is some confusion as to the
function of sewer-use regulations, and that there is
need for examination of existing laws, ordinances,
and codes covering both plumbing and sewer uses.
Sewer-Use Ordinances and Regulations
The preceding survey illustrates how jurisdictions
react to permitting direct inflow connections from
building sources. It also underscores the need for
better regulation and enforcement. In a survey of
inflow control by state and provincial water pollution
control agencies, 38 states and four provinces
reported they recommend specific policies on
sewer-use ordinances or regulations covering entry of
extraneous water into sewer systems, while 12 states
and four Canadian provinces said they do not become
involved.
The survey of consulting engineers asked if they
have prepared sewer-use ordinances for client
jurisdictions. Almost 50 percent reported that, in the
process of conducting infiltration and inflow
investigations, they recommend or draft such
ordinances.
In the conduct of the national statistical survey,
the jurisdictions were asked if they have enacted
sewer-use ordinances. Table 29, National Statistical
Survey — Sewer-Use Ordinances, contains a summary
of the responses.
Only 10 percent of respondent jurisdictions
reported the absence of such regulations; another 10
percent supplied no information. In most regions,
including Canada, positive responses ran 10 to 15
times higher than no-regulations responses. The East
reported the lowest ratio — 5 to 1.
TABLE 29
NATIONAL STATISTICAL SURVEY
SEWER-USE ORDINANCES
Region and
Population Group Yes No No Answer
East 37 7 1
South 23 4 1
Midwest 33 2 0
Southwest 22 2 1
West 52 4 3
Canada 18 2 1
200,000+ 38 1 0
100,000-199,999 25 5 1
20,000- 99,999 86 11 2
10,000- 19,000 28 3 3
Under 10,000 8 1 1
185 21 7
Only one city above 200,000 population
reported no ordinance enacted; all those surveyed in
the under-10,000 class listed such codes or
regulations.
Obviously, sewer-use ordinances have been
widely adopted for more reasons than inflow control.
Nevertheless, examination of sample ordinances
usually reveals some reference to elimination of
"clean-water," or storm, ground, or commercial
water.
When the surveyed jurisdictions were asked if
sewer-use ordinances will be adopted or modified, the
responses were evenly divided among those who said
such action is contemplated, reported no such plans,
or were uncertain. Weighed against initial findings on
the ordinances in effect, the replies on future action
must be interpreted to mean that one-third of the
jurisdictions contemplate some code revisions while a
lesser number will adopt sewer use ordinances for the
first time.
The statistically surveyed municipalities also were
requested to comment on the quality of sewer-use
ordinance enforcement and indicate who bore the
responsibility for it. The respondents generally were
non-committal about enforcement, with only nine
saying it was done and 10 saying it was not. The
balance submitted no commentaries, perhaps not
wishing to judge the situation.
However, all answered the question concerning
responsibility. In some cases jurisdictions reported
59
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TABLE 30
NATIONAL STATISTICAL SURVEY
RESPONSIBILITY FOR ENFORCEMENT
OF SEWER-USE ORDINANCES
Plumbing Inspector 78 ___
Sewer Agency 77
Other Agency 47
Building Inspector 35
TABLE 31
CONSULTING ENGINEERS SURVEY
INFLOW CORRECTION BENEFITS
Reduced pumping loads 32
Reduction in sewer surcharges 30
Reduced treatment plant flows and bypassing . . 28
Reduced combined sewer overflows 12
that joint agency control was invoked. Table 30,
National Statistical Survey-Responsibility for
Enforcement of Sewer-Use Ordinances, tabulates
total responses.
This breakdown clearly emphasizes the existence
of overlapping and at times misplaced responsibility
not only in building-sewer control but even in the
broader area of sewer uses that are not primarily the
concern of plumbing and building departments. The
almost even split of authority between sewer agencies
and plumbing inspectors explains the lack of
specificity in reporting positive enforcement.
When these jurisdictions were asked if
surveillance would be tightened, 115 answered "yes."
and 42 "no" while 63 made no comment. A trend to
raise the level of enforcement is indicated here, but
the confusion of jurisdiction and the unpopularity of
surveillance tend to mitigate against successful action.
A number of jurisdictions supplied information
on their regulatory practices and sample form letters
used in enforcement activities. One city reported that
it threatens to disconnect the house from the sewer if
illegal inflow connections are not removed. Another
city threatens ultimate court action if voluntary
compliance is not achieved; however, the respondent
official admitted that such drastic measures would
not have an economically justifiable result.
Community pressures and individual public opinion
as well as economics are in evidence as factors
limiting effective enforcement of sewer-use
regulations.
Since controling inflow involves undoing physical
connections made either with local authorization or
illegally, it requires a multiple approach of laws,
surveillance, enforcement, and expenditure of public
and private funds if it is to be effective. In any case,
public support of any program to eliminate building
inflow connection is an absolute necessity. Without
property owner participation any corrective attempt
will meet with disfavor, distrust and dispute.
Benefits of Correction
Consultants were asked to list the most
important beneficial results of an effective inflow
control program. Table 31, Consulting Engineers'
Survey — Inflow Correction Benefits, lists the
findings.
The consulting engineers demonstrated they were
aware of the need for, and value of, determined
efforts to reduce inflow which in some systems can
produce extremely high volumes of "clean water."
Such waters adversely affect all parts of the system.
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SECTION 6
JURISDICTIONAL EXPERIENCES
Investigations and surveys conducted under the
national study project brought forth many
communications, technical articles, reports, and other
documents that illustrate actual infiltration and
inflow conditions in jurisdictional sewer systems and
waste water handling and treatment installations.
Beyond the basic data from these local agencies, as
described in other sections of this report, efforts were
made to obtain such documents and reports and
examine them for data on' jurisdictional practices,
policies and performance in sewer system planning,
design, management, and maintenance.
These engineering documents, prepared by
consulting engineering firms or local technical
personnel, have a great deal of pertinent information.
They disclose the upsurge of interest in the
infiltration-inflow problem on the part of
jurisdictions and their efforts to explore ways of
eliminating or minimizing the adverse results of
excessive extraneous waste waters entering their
sewer systems.
To make some of these interesting and
informative facts a matter of record, the following
selected excerpts from case histories of the listed
jurisdictions are included in this project report.
Hopefully, these experiences will be of value to other
local community officials faced with similar problems
and conditions.
Dade County, Florida
A letter from a consulting engineering firm
described infiltration problems in the sewer system
serving Dade County, Florida and contiguous
communities:
It was estimated in April, 1965 that the total
ground water infiltration into the system
approximated from 1.8 to 2.0 million gallons per day.
At that time, plant flows were averaging 3.3 to 3.5
mgd. Sewer repair work effectively reduced the
volume of infiltration to a point where during the
month of January, 1967 the average flow was down
to 2.0 mgd. During the first two weeks of February,
1967 an accidental break in one of the sewer lines
resulted in an increase to a rate as high as 3.3 mgd.
After this break was sealed, however, the flows were
recorded at or below 2.0 mgd. The normal rated
capacity of the plant is 2.05 mgd, or approximately
5,900 single-family residential connections or their
equivalent, based on design flow allowances of 350
gpcd. There are presently 4,800 equivalent residential
connections active in the system, indicating that an
additional 1,100 could be served before the total
capacity is utilized — if ground water infiltration can
be controlled to the extent realized during recent
flow recording periods.
Emmetsburg, Iowa
A paper prepared by a consulting engineering
firm described the infiltration problems of this
community of approximately 4,000 population.
Infiltration resulted in basement flooding during.
periods of heavy rainfall; sewage treatment plant
overloading, which necessitated by-passing; heavy
deposition of sand and other debris in the sewer
system, and reduction of the carrying capacity of the
entire system. The city finally decided that something
had to be done.
With the help of an engineering support
organization, the city analyzed its entire system and
initiated a program of correction. The sanitary system
comprises approximately 85,000 feet, or 16 miles, of
sanitary sewers, ranging in size from 6 to 20 inches.
About 290 manholes are in the system. In addition,
there are some 100,000 feet of storm sewers ranging
in size from 12 to 48 inches. During periods of heavy
rainfall and high ground water, infiltration exceeds
the maximum capacities of the sanitary sewers. The
objective of the survey was to answer these questions:
Where in the 16 miles of sanitary sewers do we start
looking for the infiltration problem? How do we
relieve the flooded basement situation? On what
hydraulic basis do we design modifications to the
waste water treatment plant? How do the restricted
sewers affect the flooded basement problem? Are the
lift stations adequate to handle the flows expected?
How much money will be required to solve all these
problems?
A multi-phased program had to be established to
accomplish the goals, similar to that referred to in
Section 4 of this report. Th'e conclusions based on the
studies were as follows:
1. Of the 84,839 feet of 6- to 20-inch sewers
physically inspected, approximately 35,592
feet, or 42 percent of the system, needed
major cleaning.
2. The general nature of restriction in most of
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the sewers was found to consist of sand and
sludge, with some root penetration evident.
The conventional method of bucketing was
required in all districts, but the high velocity
jet could be used in varying degrees where
the top of the deposition allowed.
3. It was estimated that 1,461 to 1,928
crew-hours of cleaning were needed to
restore self-scouring velocities to all the
sewers inspected and thoroughly prepare
them for the TV inspection.
4. As a result of a rainfall simulation study,
areas to be televised in quest of infiltration
were isolated. These areas were the first to be
cleaned.
5. To clean the sanitary sewers in which
infiltration was found would require 516 to
645 crew-hours; 28,218 feet are involved, or
about 33.3 percent of the total system.
Flint, Michigan
In September 1969, a preliminary draft of a
report entitled, "Study of Sanitary and Storm Sewer
Systems," was presented to officials of the city. This
study comprehensively reviewed existing storm and
sanitary sewers, with flow measurements, visual
inspections, and many analyses by the consultant to
determine the course of future action for the city.
Some of the conclusions and recommendations are
pertinent to the national study:
• Reduction of the amount of extraneous flows
to the sanitary system, modification of the
downstream section of the west side interceptor, and
separation of the combined sewers in the downtown
area would eliminate overflows to the river.
• With few exceptions, the major sanitary sewers
in the city have sufficient capacity for future flows, if
the entry of excessive extraneous flows is reduced.
The importance of accomplishing this work was
stressed. The need for greater attention to repairs and
maintenance was apparent, particularly in the
terminal chambers of the inverted siphons and in
defective manholes.
• Investigation showed that extensive areas of
roofs and pavements were connected into the sanitary
system tributary to a major pumping station.
Elimination of the major sources of excessive flow
was determined to be practicable and essential to the
efficient development of the sewage conveyance and
treatment facilities and reduction of overflows from
the northwest areas.
It was determined that:
1. Most basement flooding incidences are
associated with defects in house drainage
systems in areas affected by ground water. In
only a few instances would flooding
problems be reduced greatly by increasing
the capacity of the storm or sanitary sewer
systems. Other more effective and less costly
measures to alleviate basement flooding are
available.
2. Systematic measures should be taken to
detect and eliminate sources of excessive
extraneous flows into the sanitary sewer
system due to discharges from roofs,
pavements, watercourses and ground water
reservoirs.
3. Regulations should be enacted to prohibit
the future connection to the sanitary sewer
system of exterior foundation drains or other
sources of surface water or ground water.
4. The staff assigned to sewer system and plant
maintenance and to laboratory duties should
be expanded and additional funds provided
to maintain and operate the system properly.
Hutchinson, Minnesota
Hutchinson, population 8,500, has a sewer
system of approximately 130,000 feet, or 26 miles,
of 8- to 15-inch lines, plus 28,000 feet of interceptor
lines ranging in size from 15 to 24 inches. As an
aftermath of a flood in 1965, about 22,000 feet of 8-
to 15-inch sanitary sewer lines were cleaned and
repaired. At that time this was about 22 percent of
the sanitary system.
The engineer reported at a recent sewer
management seminar that his department will be
cleaning and televising about 21,000 feet of sewer
lines prior to a proposed two-year street paving
program. When this is completed, 43 percent of the
system will have been cleaned and televised.
In addition to using TV cameras to determine the
extent of flood damage, the city has extended the
technique to buying what is described as "paving
insurance." In conjunction with a $1.5 million paving
program, the cost of cleaning and televising sewers
will be about $20,000, considered to be an extremely
worthwhile and minimal expenditure.
The greatest value of television lies in the
inspection of new sewer construction. The city
engineer is convinced that its use has provided the
city with high quality construction.
The city considers the TV expenditure a part of
the engineering services; it should not be paid for by
the contractor as part of his bid. There are too many
instances when re-televising of a particular section is
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necessary. With the city assuming this function, it has
complete control of the time of inspection and the
subsequent review of the reports.
On a recent project the contractor paid
approximately $4,600 to seal leaks on a construction
project, plus whatever costs were entailed in the
physical replacement of the few broken pipes. The
city did not have to bear this burden. The city's
expenditure of $900,000 (plus interest which will
almost double the figure) for its new interceptor
sewers was for quality work, as all of the pipe was
inspected.
Milwaukee, Wisconsin
In 1968 and 1969, the City of Milwaukee carried
out "an in-depth review of sewer cleaning problems as
it relates to municipal services." A report on this
survey was prepared by the Bureau of Street and
Sewer Maintenance. (Excerpts from this report are
contained in the Manual of Practice which is an
integral part of this national study report.) Although
this study was mostly concerned with the problems
of providing top quality maintenance procedures and
personnel, there was a definite correlation between
proper,, preventive maintenance and reduction in
infiltration problems. There also was a connection
between the cost of correcting infiltration and the
ability to provide clean sewers for inspection and
correction activities. The report pointed out that as
the mileage of the total sewer system increases, the
average "capacity index" of the municipality
decreases. As the city gains in size, its ability to pay
the cost of an effective sewer cleaning program fails
to keep pace. Historically, it pays more attention to
the more obvious above-ground defects and overlooks
the "hidden" obsolescence underground - regardless
of the continuing proportion of "need." The only
exception lies in the "official acceptance" of a
priority for sewers that is the same as those assigned
"above-ground" urban problems.
The report recommended greater recognition, not
only of the problem involved in maintenance and
control of infiltration, but of the importance of the
people called upon to provide these services. It urged
that: 'To improve morale, steps should be taken to
erase any sense of 'second class citizenship.1 A sewer
maintenance reorganization study should be made
and serious consideration given to the relative
importance of the sewer services being provided and
the technical skill and knowledge required to get the
job done. Appropriate pay scales and titles should be
assigned that will tend to equalize 'citizenship status'
among all public works employees."
New Providence, New Jersey
In 1964, the Borough of New Providence engaged
a consulting engineer to prepare a report on "The
Investigation of Infiltration in the Borough of New
Providence Sanitary Sewer System."
The New Providence system has 41 miles of
sewers with a replacement value estimated at $3
million. It was reported that infiltration and leakage
always had been inherent in the collection system and
was not a recent occurrence. In newer portions of the
system, pipe and jointing procedures were reduced
resulting in a decrease in the proportion of domestic
and industrial waste infiltration, instead of increasing
as the collection system grew. Present leakage and
infiltration amounts to an average of about 200,000
to 250,000 gallons per day, or some 15 percent of the
average daily flow. In a very wet month, infiltration
will range from 300,000 to 400,000 gallons per day,
and drop during extremely dry periods to as low as
100,000 gallons per day.
If the borough had a relatively tight sanitary
sewer system, utilizing the most effective joints, it
was estimated that the system flow would average
1.05 to 1.1 instead of about 1.3 mgd. Likewise, it was
believed that in the maximum months the flow would
be reduced from about 1.8 to 1.4 mgd. There would
be little reduction in flow during the minimum
months since little infiltration occurs in dry-weather
periods.
The report stated: "Based upon records for
infiltration control, and on the assumption that 70
percent of the borough system would require repair,
it was estimated that the approximate cost of sealing
and repairing of joints in the collection system would
range from $225,000 to $375,000. It was also
estimated that this repair might reduce system
leakage by 150,000 to 200,000 gallons per day, the
equivalent of 55 to 73 mg per year. This would be
equivalent to an average annual expenditure of from
$11,250 to $18,750, or from $200 to $350 per
million gallons per year."
The report called for continued investigations
and advanced methods of inspecting existing systems
to correct excessive amounts of infiltration and
inflow.
Oakland County, Michigan
In 1967, Oakland County's Department of Public
Works carried out a "Drain Tile-Test Pilot Project,"
initiated upon a request by building developers to
connect building tile drains and foundation drains to
the sanitary sewer system and the building sewers.
Over a period of one and a half years, numerous flow
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records were made and correlated with rainfall
measurements. The report concluded that the
subdivision contributed peak flows exceeding design
flows and that therefore the development had a
detrimental effect on the system. The staff of the
Oakland County Public Works Department concluded
that the major cause for this subdivision's difficulties
was the clay soil underlying the area. A somewhat
similar test subdivision in a sandy soil area
contributed no flow to the sanitary system because
most of the rainfall percolated past the tile to the
deep water table, instead of being held in a pocket as
in the case of the clay soil area.
The report recommended that all buildings
installing drain tiles be prohibited from connecting
directly or indirectly to certain interceptors.
Later tests made on a series of individual
buildings, as well as a former research project,
indicated there was a direct connection between
rainfall on roofs discharged onto ground adjacent to
foundations, and the flow of ground water into
sanitary sewers from the drain tiles. It was found that
severe infiltration flow problems existed when roof
leaders discharged next to the foundation walls.
Installation of splash blocks diverted the flow about 5
feet into the yard area and effectively eliminated the
infiltration of such flows into foundation drain tiles.
Elko, Nevada
In 1968, Elko engaged engineering consultants to
prepare a water and sewage Master Plan. Part of this
required planning for sewage flow and treatment. The
consultants' basic assumptions are given in the
following tabulation:
Master Plan
Existing Conditions
Year 1968 1985
Sewage Flow
Av. daily dry-weather
flow in gallons 1,500,000 2,200,000
Per capita flow —
basic population 172 160
Estimated infiltration
flow(gpd) 1,800,000 2,800,000
Peak dry-weather
flow 1,800,000 2,800,000
Sewage Characteristics
Biochemical oxygen
demand (mg/1)
(5-day—20 degree
centigrade) 140 160
Per capita equivalent
BOD Obs. per day) 0.20 0.22
Suspended solids
(mg/1) 115 140
Grease (mg/1) 37 40
The consultants pointed out that the relatively
low BOD concentration reflected the dilution caused
by infiltration of ground water into the collection
system. Otherwise, sewage characteristics were typical
of domestic sewage.
The consultants made the following comments
on the existing sewage system: The existing sewer
system consists of 157,000 lineal feet of trunk
collection sewers, sewage lift stations, and an existing
waste water treatment plant with ponds.
Collection sewers primarily are vitrified clay pipe
with poured bituminous joints. Some recent
construction has utilized concrete sewer pipe. Except
for a few recent systems using 6-inch pipes, the
minimum size of collection sewers is 8 inches. No
serious collection sewer capacity problems are
evident. A continued program of cleaning, using the
city's high-pressure hydraulic equipment, will
minimize collection sewer problems.
The high per capita sewage flow rate and the low
organic strength of sewage indicate there is
substantial infiltration into the collection sewer
system. Considering the high cost of multiple
pumping and treatment of sewage flow originating in
the low-lying areas adjacent to the river, a program to
minimize infiltration from these areas appears
justified.
Lexington, Kentucky
Lexington, Kentucky in 1957, carried out
investigations and studies of infiltration into the
sanitary sewer system of the Idle Hour subdivision in
that city. Consultants were asked to investigate and
report on the apparent infiltration of storm and
ground water into a sewer system consisting of
approximately 24,000 feet of 8-inch vitrified clay
pipe collector sewers, 700 feet of 4-inch cast iron
force mains, and 4,800 feet of 6-inch cast iron force
mains.
One conclusion of the report was that: "As a
result of the various investigations and studies
described earlier in this report, the conclusion is
reached that there are two main sources of
infiltration into the system. One of these sources is
infiltration; that is, ground water which is seeping into
the sewer system through joints or holes in the pipe
and manholes. The other source, which seems to
contribute the greatest amount of excess water, is
surface or storm drainage; that is, water other than
sanitary sewage which is either piped into the system
or gets into the system from standing on or around
manholes."
There are numerous locations where foundation
drains either are pumped by sump pumps or flow by
gravity into the sewer system. In some cases the
foundation drain and underdrains are connected into
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the sumps from basements. But in cases where there
are no basements, the water flows from under and
around the houses by gravity into the sewer or is
pumped into the sewer by sump pumps. In a few
other instances it was apparent that roof drains were
connected into the sewer. These drains go into the
ground without any indication that they discharge at
the street or onto the ground.
The consultants recommended that all the
foundation drains, basement underdrains, and roof
drains be disconnected from the sanitary sewer
system; that the manhole deficiencies be remedied,
and that all sewer line and house or building sewer
connections should be excavated at points where
investigations revealed an apparent excessive amount
of infiltration. It was discovered during the course of
the investigation that "Y's" and "T's" left for
connection in the street sewers were, in many cases,
not used; that holes were simply punched in the
street sewer to allow insertion of the building sewer
consultants recommended that all suspicious
connections of that type be exposed and
reconstructed.
Lincoln, Nebraska
Recently Lincoln, Nebraska engaged consulting
engineering services to investigate certain areas that
have caused sanitary sewer flow problems. In each
investigation, water consumption records as well as
weir measurements were used to determine the
condition of sewage flow at various times of the day
and year.
In one study, three possible problem sources
were listed: (1) inadequate sewer capacities; (2) poor
sewer flow characteristics, and (3) excessive discharge
rates from commercial operation. After investigation
and analysis, the following conclusions and
recommendations were submitted:
1. Comparison of actual measured flows with
winter-quarter water consumption did not
indicate cooling water being discharged into
the sewer system.
2. Flow metering disclosed some storm water
infiltration during a 1.26-inch rain of
moderate to light intensity occurring on May
7, 1969. Since the maximum flows were not
excessive, it was decided that smoke
bombing of the study areas did not appear to
have significant value.
3. Flow measurements definitely showed that
the sewer on Adams Street is critically
overloaded from time to time because of
wash-down operations at a local commercial
establishment.
Another survey in a different area listed the
following as possible problem sources: (1) inadequate
sewer capacities; (2) excessive cooling water discharge
into the sanitary sewer system, and (3) excessive
storm water infiltration.
Comparison of actual measured flows with
winter-quarter water consumption indicated discharge
of cooling water into the sewer system. At this time,
the cooling water is not the primary cause of
problems in the area; however, increased discharges
into the sewer system could cause future problems.
The city was urged to discourage this practice.
Flow metering did not disclose any excessive
storm water infiltration in the area during a 2-inch
rain of moderate to light intensity occurring on
September 16, 1968. Because of this, it was decided
that smoke-bombing the study area would not be of
significant value.
A third study in Lincoln presented the following
factors as possible causes of infiltration problems: (1)
connection of roof and area drains to the sanitary
sewers; (2) footing drains connected to sanitary
sewers; (3) excessive amounts of cooling water being
discharged to the sanitary sewer; (4) excessive
infiltration through the ground water surrounding the
pipe in the downstream portion of the system, and
(5) insufficient capacity in a part of the system.
A complete program of smoke-bombing was
recommended for this area on all lines built prior to
1926, in view of the problems found in the areas
checked. Measures to eliminate illegal area drain
connections and broken lines were urged.
The consultants urged that consideration be given
television inspection of the older sewers in the area to
determine the condition of the lines. Defective joints
increase infiltration, permit root intrusion, and add to
maintenance problems. It was recommended that
houses having faulty venting revealed in the
smoke-bombing should be notified so that they
immediately can take corrective steps.
Southeastern Michigan, Six-County Metropolitan Area
In 1964, a team of consultants submitted reports
to a 6-county committee in the Detroit area regarding
a sewage and drainage study. This report
comprehensively reviewed many factors in carrying
out master planning activities far into the future for
this large regional area. Among the many factors
discussed was the importance of the infiltration and
inflow problem.
The report pointed out that if storm, surface, or
ground water is admitted into a separate sewer, there
can only be one result — flooding of the system and
connected basements. This was best illustrated by the
fact that a population of 2,000 people living on an
area of 200 acres requires a separate sewer of 12-inch
diameter with a capacity of 1.20 cfs. A storm sewer
for this area would need to be 60 inches in diameter
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with a capacity of 120 cfs. As a further illustration, a
one-inch hole in a manhole cover, flooded with 6
inches of water, will admit 8 gallons per minute, the
equivalent of a sewage flow from 10 homes.
Separate sewers can function satisfactorily if each
of the following conditions is met: all sewers,
including house connections, are constructed with
watertight joints; all manholes are of watertight
construction and with covers of the solid type; all
roof water and surface water are excluded by
ordinance from the separate sewer system; by
ordinance, footing drains below the normal ground
water table are excluded from the separate sewer
system; adequate inspection is provided by the
responsible authority to assure compliance with the
ordinance; adequate maintenance of the sewer is
provided by the authority.
The engineers noted that the Great Lakes-Upper
Mississippi River Board of State Sanitary Engineers in
its "Recommended Standards for Sewage Works,"
under design of sewers, type of system,
stipulates that: "In general, and except for special
reasons, the reviewing authority will approve plans
for new systems or extensions only when designed
upon a separate plan, in which rain water from roofs,
streets, and other areas, and ground water from
foundation drains are excluded."
Redding, California
In 1967, a consultant submitted a report to the
City of Redding on "The Sources and Correction of
Infiltration." The report concluded that:
1. Wet-weather flows in Redding's sewer system
are as much as five times the dry-weather
flows. This is due to infiltration and as a
result the capacity of the system is exceeded.
2. While the quantity of infiltration is relatively
easy to measure, locating its source is very
difficult. The older portion of the system
constructed from 1890 to 1940 contains
about 127,000 feet of lateral and trunk
sewers and about 90,000 feet of connection
or building sewers. The former are
municipally owned; the latter are privately
owned. The heaviest infiltration flows take
place in these older sewers, particularly those
which cross or are near drainage channels.
3. Using a television camera, a "pilot program"
of internal viewing was conducted in
representative portions of the older system.
In addition, some pipe and joints were
exposed for external examination. Defects
found included broken pipe, root infestation,
poor connections, and poor joints. Projecting
the results of the pilot program to the total
older systems, it is estimated that from 30 to
40 percent of the pipe is in need of some sort
of repair.
4. Methods of correction include: (a) chemical
grouting (which may be preceded by root
treatment); (b) excavation and repair, and (c)
abandonment and replacement.
5. Total estimated cost of the repair program,
which included lateral and trunk sewers,
connection sewers, manholes, and additional
internal viewing, was $433,000; consisting of
$319,000 for municipally owned facilities
and $114,000 for privately owned building
sewers.
6. The work could be conducted in stages,
utilizing city forces to a large extent. If
staged, it should be pursued actively or it
probably will not be done.
The report recommended:
1. A state program of correction should be
initiated. This should start with a systematic
and thorough investigation of all known or
suspected sources of major
infiltration - primarily at drainage channels.
As these are found, repairs or replacements
should be made. Later stages of this program
will consist of root treatment and chemical
grouting.
2. All existing abandoned sewers should be
investigated and checked to make sure they
are sealed off from the active system.
3. As areas change in use or undeveloped lands
are developed, the city should relocate and
replace all old sewers, particularly below the
ground water table.
4. The city now has good standards for the
installation and inspection of new work.
These standards should be rigidly enforced so
that no new sources of infiltration are
created.
Another point made in this report was that
design capacities are going to be exceeded. One
particular interceptor sewer was designed with
sufficient capacity for the estimated ultimate
population of its surface area, provided that new
tributary sewers are properly constructed and that
existing infiltration flows can be reduced. On the
other hand, if existing infiltration is not reduced and
if infiltration is allowed to increase in other parts of
the system, it will be necessary to parallel this sewer
in the future. It also would be necessary to provide
sewage pumping and treatment facilities far beyond
those anticipated. Obviously, this situation is not
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economical, and a substantial reduction in infiltration
must be achieved.
Oakland and Berkeley, California
A recent study of "Storm Water Problems and
Control in Sanitary Sewers in Oakland and Berkeley,
California," was prepared by a consulting engineering
firm, under a contract with the Federal Water
Quality Administration, covering the East Bay
Municipal Utility District No. 1, with assistance from
the two cities. The problem and the study area were
described as follows:
"Infiltration into sanitary sewers has plagued
engineers and municipal officials for many
years. Every sewer system is subject to
infiltration to some degree, depending upon the
condition of the sewers, the level of ground
water, and the soil conditions. The extraneous
flows from infiltration into sewers use up
valuable hydraulic capacity. Subsequently, such
flows reduce the treatment capability of water
pollution control facilities by creating
abnormally high flow rates. High flow rates
upset biological activity. Storm water
infiltration results from the use of inadequate
construction materials, poor construction
practices, and direct connections. Until
recently, sewer construction materials and
practices were frequently conducive to
infiltration because poor joints were produced
when the pipe was laid. Rigid jointing materials
fractured during pipe settlement, permitting
ground water to enter or sewage to escape the
pipe. With improvements in construction
materials such as flexible plastic joints, the
problem of infiltration in recent sewer
construction is greatly reduced. However,
sewers that were built before the improvements
in construction materials and methods were
developed — around 1960 — have many years
of useful life remaining, and it is not likely that
they will be replaced before the end of that
useful life is reached. Direct connections, such
as roof, yard, and foundation drains, add to the
quantity of infiltration, especially during wet
weather. In many instances, these connections
are not only difficult to locate but also difficult
to disconnect because of the political
ramifications involved. For these reasons, the
general problem of infiltration will continue for
many years."
Attempts were made during the course of the
investigation to estimate the volumes of storm water
infiltration. It should be pointed out that the
terminology used in this East Bay study was slightly
different from that of the APWA project report on
infiltration. In the East Bay study, infiltration
includes both classical infiltration into leaking pipes
and what has been called inflow, or the direct
connection of extraneous water. The report
concluded, among other points:
"Infiltration ratios (the volume of infiltration
to the volume of rainfall) were defined both for
gross infiltration and for infiltration from each
of two sources: percolation and direct
connections. The gross infiltration ratios for
selected study sub-areas range from 0.01 to
0.14 depending upon land use topography and
age or condition of the sewer system. The
drainage area that contributes directly to pump
station "A" was found to have a ratio of 0.246,
about 60 percent of the infiltration was
attributable to percolation and 40 percent to
direct connections for the eight sub-areas
evaluated."
In the course of the study it was found that 11.1
percent of the total volume of rain falling on the East
Bay area enters the sanitary sewer system.
Approximately 30.6 percent of the total volume of
infiltration is contributed by infiltration and runoff
from those areas which have combined sewers,
composing 4 percent of the study area. About 3.7
percent of the total volume of infiltration is
contributed by Pump Station A Drainage Area,
composing 1.4 percent of the study area. In the
remaining 94.6 percent of the study area,
approximately 26.2 percent of the total infiltration is
contributed via direct connections and 39.5 percent
via percolation or pipe leakage.
The consultants pointed out that because of
political ramifications, lack of full cooperation from
the citizenry, and apparently because of special
soil-condition problems in the area, elimination of
illicit or direct connections from private property
would not be a practical solution—although a
selective program would be of value. It was
recommended, however, that all catch basins be
disconnected from sanitary sewers.
The report stated, "No single action, short of
total sewer replacement, could be found to solve the
infiltration problems." A series of component
solutions was evaluated. The most practical and the
least costly combination of these was concluded to be
the following: "(1) Complete about 50 percent of the
remaining sewer separation program; (2) provide
improvements to the water pollution control plant;
(3) locate and disconnect catch basins that are
presently connected to the sanitary sewer system; (4)
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provide partial treatment for the remaining overflows;
and (5) eliminate sewer system bottlenecks." It was
suggested that such a plan would take about seven
years to complete.
City of St. Claire Shores, Michigan
In 1968, the city engaged consultants to evaluate
its interceptors and examine problems of basement
flooding. The subsequent report discussed the
basement flooding problem as follows: "Elimination
of basement flooding will occur when all sources of
storm water entering the sanitary sewer system are
eliminated." Possible sources of storm water are: (1)
storm sewer catch basins and/or roof conductors
connected to the sanitary sewer; (2) broken or
improperly constructed sanitary sewers, and (3)
surface water infiltration via weep-tile (footing
drains) at homes with basements.
The city engineer has instituted a program to
locate and eliminate storm water connections from
storm sewers, catch basins, and roof conductors.
Residential roof conductors have been eliminated,
and extensions have been required by city ordinance
to discharge storm water away from the basement
wall. The city has started a program to inspect,
determine the amount of infiltration, and repair
joints in the sanitary lateral system. The report
mentioned the studies that were made by Oakland
County Department of Public Works. Data for six
locations after a storm on December 21, 1967, are
listed as follows: (1) The peak rate flow for sample
points which has footing drains connected to the
sanitary sewer was 2.6 to 5.2 times the design flow of
0.4 cfs/1000 population (260 gallons per capita per
day); (2) the peak rate of flow for sample points
which did not have footing drains connected to the
sanitary sewer was 1.3 times the design flow of 0.4
cfs/1000 population.
Springfield, Illinois
In 1966, the Springfield Sanitary District
instituted a program of downspout removal from
sanitary sewers. This was administered by the
Sanitary District staff. The project report states:
"The quality of sewer construction has been under
close scrutiny during the past few years. Allowable
infiltration or exfiltration has been drastically
reduced. As a result, considerable improvement has
been made in sewer jointing in an attempt to meet
these more stringent standards. While improvement in
construction practices is certainly to be encouraged,
we can hardly hope for the changes in construction
practice to bring improved results in our sewer
systems unless the other factors which cover
overloading of the sewers are also properly considered
and corrected.
It must be remembered that in a normal
community, the footage of house services is far
greater than the street sewers. Too often, poor
inspection, or no inspection, is made of the house
services with the result that they contribute
considerable volumes of water to the sewer system
through infiltration. Also in many places footing tiles
discharging to the sewer systems are legally or
illegally constructed around buildings. In many places
roof downspouts are also discharged to the sewers
either legally or illegally and they also contribute
considerably to the hydraulic loading of the sewers.
It, therefore, seems quite inconsistent to demand a
high degree of construction quality in the street
sewers without also preventing the entrance of
surface and ground waters into the same sewer system
from other sources. While the control of extraneous
waters into the sewer system from these other sources
may be much more difficult to control than the
construction practices on new sewers, they must be
controlled if we are to make the present construction
practices meaningful and productive in reducing the
volumes of superfluous water that presently reach our
sewer systems."
The District investigated the existence of
downspout connections by actual on-site inspections
and by the use of questionnaires. After establishing
the possibility of certain homes being in violation, a
series of letters were sent to the homeowners,
requesting compliance with ordinances and
regulations. After a series of follow-up inspections,
there were further letters to property owners.
Considerable success was achieved in reducing
downspout connections.
Second inspections revealed that less than 2
percent of the original number of buildings were still
connected to the sewers.
The report said the number of downspouts with
lapsed connections was a serious problem in these
areas. However, the results obtained in reduced
basement flooding as a result of the campaign were
classified as excellent. Previously the Sanitary District
office had received as many as 300 complaint calls in
a single day about basement flooding; the sewer
construction and downspout campaign virtually
eliminated such calls.
Southfteld, Michigan
In 1969, consultants submitted a report to the
city officials covering investigations of sewer and
drain conditions that caused local flooding of streets
and basements. The studies were prompted by severe
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flooding during the major storms of 1967-1968.
The consultants pointed out that in designing
combined sewers, engineers calculate that 98 percent
of the capacities will be used for storm water runoffs
and only 2 percent for sanitary sewage.
This report parallels others prepared for the
Oakland County area, where the county department
of public works has been a leader in investigating
excess water in sanitary systems and in developing
corrective measures.
Some steps already had been taken to solve these
problems including: design of eight new major drains
costing $3.9 million; design and/or construction of
several major sanitary subtrunk lines at a cost of
additional millions; the replacement of perforated
manhole lids in certain critical areas; and expansion
of the city's ditching program.
The report contained 19 recommendations, with
proposed assignments of the responsibility for
implementing them. One recommendation was that
the city should exert every effort, through meetings,
lectures, and written materials, to make citizens
aware of the problems connected with flooding due
to infiltration and inflow, plus necessary corrective
measures.
It was further recommended that:
1. All ordinances relating to the questions of
drainage and sewerage be reviewed by the
city attorney and the appropriate city
department to determine whether such
ordinances provide the protection for which
they were originally intended, and whether
penalties currently provided for are adequate
to eliminate repeated violations.
2. Any ordinance or sections of an ordinance
relevent to the matter of flooding of sewers
which are not enforceable be rewritten in a
manner that will expedite enforcement.
3. All ordinances be enforced uniformly.
4. Footing connections to the sanitary sewer
system be disallowed.
5. The city hire at least two enforcement
inspectors in the building department, whose
sole job would be to provide expanded
inspection and enforcement of all
ordinances.
6. All residents install conductor boots to
downspouts or provide splash blocks so that
roof water is discharged at least 5 feet from
foundation walls.
7. All foundation planting beds, and lawns be
graded, or regraded, to provide a continuous
5 percent grade downward and away from
any building to a distance of at least 10 feet.
8. Solid sanitary or combined sewer manhole
covers be utilized wherever deemed necessary
to restrict inflow of storm water, and that
such covers are to be removed only by
authorized persons.
9. All conventional sump pumps and patio
drains be disconnected from the sanitary
lines wherever they have been connected
illegally.
10. City enforcement inspectors be particularly
vigilant in the case of plugs being removed
from the sanitary outlets and open basement
drains.
Stamford, Connecticut
In 1969, consultants were retained to conduct
investigations and report on the capacity and
condition of existing sanitary sewers in Stamford.
Investigations used city employees to reduce the
time for the study. Each manhole was opened in the
study area, and the flow and condition of pipes were
recorded. Approximately 25 percent of the manholes
in the study area were found buried beneath
pavements. Measurement of flows in manholes during
both rainy and dry weather was carried out to detect
ground water infiltration and/or storm water
contribution. Among the manholes studied, one was
found to have 140 times the design flow in dry
weather, because of continuous ground water
infiltration. Other manholes recorded 25 to 35 times
the theoretical flow during dry weather. In a number
of other manholes the wet-weather flow was two to
three times the dry-weather flow, indicating illegal
connections.
Pumping station records showed that storm water
runoff entered the sanitary sewer system at some
points. The rather rapid and abrupt pattern of change
of flow at the pumping station, and the pattern of
high inflows during rainfalls, led to the conclusion
that the runoff entry resulted typically from direct
connection of storm water drainage to the sanitary
sewer lines rather than from infiltration. It was
concluded that the heavy inflow rate was the result of
illegal connection of roof or yard drains or an
inadvertent cross-connection between the storm
sewer system and the sanitary sewer system, or even
the location of a sanitary sewer manhole at a point
where storm water runoff could flow directly into
manholes or pipes.
It was recommended that a comprehensive
cleaning and repair program be instituted; that all
abandoned house services and illegal connections be
plugged; that a television survey be made to
determine where faulty pipes and joints are located;
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that repair of manholes and installation of watertight
manhole covers be instituted, and that there be
smoke testing of sanitary sewers to detect illegal
connections.
A budget estimate for this work was developed,
assuming that all parts would be cleaned and also that
not more than 50 percent of the pipe joints would
require repairs. With an added dollar amount of
$3,000 per mile of sewer for incidental repairs, it was
estimated that implementation of the recommended
procedures would cost about $300,000, or 4.6
percent of the city's investment in these sewers,
represented by an estimated total replacement cost of
$6,500,000.
It was suggested that a system of "monitored
manholes" be established throughout the city.
Selected manholes at key positions should be
monitored manually or with recording instruments to
detect the presence of major infiltration and major
changes in flow. This might indicate, among other
things, approaching inadequacy of given sewers, or
illegal connections.
Stonybrook Regional Sewerage Group, New Jersey
In October 1969, a consulting engineering firm
submitted a report on recommended waste water
collection and disposal facilities for a group of
municipalities surrounding Princeton, New Jersey.
Sections of the report related to the infiltration and
inflow problem, which is extremely severe in the
Princeton system. The consultants drew 32
conclusions from the study. Two of these related to
infiltration conditions:
1. Ground water infiltration in the Princeton
collection system is higher than normal and
is attributable to the materials of
construction used in the latter part of the
century, when many of the sewers were
constructed.
2. There are several locations in the Princeton
sanitary sewage system at which overflowing
or by-passing of untreated waste water occurs
during times of peak flows in the system.
The magnitude of peak rates attained in the
system is the result of many unauthorized
drainage connections being made to the
sewers designed as separate sanitary sewers.
It would not be practical for the design of
the regional sewage facilities to be based on
the continuation of these drainage
connections.
The extraneous water flows in the system were
recognized as being so important that an entire
chapter was devoted to a discussion of peak flow
rates encountered in the Princeton sewer system.
Hydraulic studies indicated that the peak flows
reached a rate of 35 mgd. Since the maximum rate
that can be discharged to the main sewage treatment
plant by means of the River Road Pumping Station is
on the order of 8 mgd, the remainder of the flow is
discharged through the pumping station by-pass,
overflow pipes in the manholes, and manhole covers
in outlying areas. Overflows were as follows: 4 mgd
through the pumping station by-pass, 18 mgd through
manhole overflow pipes, and 5 mgd through manhole
covers.
In discussing the problem, of extraneous flows in
Princeton the report makes the following comments:
"The existing waste water collection system
owned by the Princeton Borough and Township
as well as Princeton University, was intended to
be a separate sanitary sewer system. However,
through the years many unauthorized
connections have been made to the system; this
has allowed the discharge of storm sewage and
ground water into it from roof and yard drains,
foundation drains, sump pumps and other
miscellaneous drainage pipes. The net effect of
these drainage connections has been the
conversion of the collection system into a
combined pipe. While many of these
connections have been eliminated in the past, a
large number of them still remain and exert
their influence in the form of higher than
normal flows at the waste water treatment
plant and surcharge sewers that cause waste
water discharges through manhole covers or
overflow pipes that have been provided to
relieve the overloaded condition."
Concerning the question of correcting
infiltration, as opposed to eliminating the inflow of
direct storm connections, the consultants stated:
"As the Princeton sewer system is an old one,
dating back to the late 1800's, a significant
portion of it was constructed of materials
which provide much less resistance to ground
water infiltration through pipe joints and
manholes than sewers constructed with present
day materials can provide. Therefore, it is felt
that the greater part of the infiltration is in the
system and cannot be reduced through
corrective measures. However, efforts should be
made to eliminate as many drainage
connections as can be located to reduce the
load on the sanitary sewage system to the
greatest extent possible."
Toronto, Canada
A report of the Commissioner of Public Works of
Toronto to the Public Works Cpmmittee described
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methods to eliminate infiltration in some old sanitary
sewers. The sewer system is 933 miles in length, with
a replacement value of $330 million having an
unexpired value of $137 million. A series of
investigations disclosed many defects in the existing
system. Many of the pipes had developed serious
spiderweb or alligator cracking, longitudinal and
circumferential cracks, open and displaced joints,
hard calcide or grease deposits, and tree root
intrusion. It also was found that many of the private
drains and building sewers were improperly installed,
with the extremity of the drain protruding into the
sewer.
Starting in 1965, the City of Toronto began a
program of new storm sewer construction, thus
removing some of the combined sewers from the
system and permitting the older sewer to revert to
sanitary use. In 1966, the Commissioner began
experiments on the relining of existing sewers with
high density plastic pipe liners.
For the initial pilot project, which included
development of rotary rooter type equipment and
many other onetime charges, the overall unit cost for
relining was $50.90 a foot. In subsequent operations
the cost was reduced to $22.65 per foot. The
commissioner estimated that the conventional
open-cut method of complete sewer replacement
would cost between $30 and $50 a foot in Toronto.
With $35 a foot as a realistic reasonable average cost
for complete reconstruction, relining was estimated
to cost 35 percent less than replacement.
Wichita, Kansas
In 1961, the City of Wichita, Kansas, engaged
consulting engineers to study the problems of
flooding as a result of infiltration and inflow in the
southwest section of the city.
The report indicated that in 1953 through 1956
the city had installed sanitary sewer mains, submains,
and laterals, to provide sewer service to an area of
about two square miles in the southwest part of
Wichita. The -arealiad a generally flat topography and
a normally high ground water elevation. The sewer
depth varied from 4 to 17 feet. In most of the area
the depth was sufficient to accommodate basement
floor drains. Normal rainfall in Wichita is 28.4 inches
per year. The rainfall in 1952 through 1956 averaged
18 inches per year, or 10.4 inches per year below
normal. In those years the sewers were constructed at
a time when the ground water elevation was several
feet below normal. The building sewers were
constructed of clay pipe and bituminous fiber pipe.
Many of the houses had basements. Some houses
were constructed as two-story houses, with the lower
level approximately 4 feet below the yard grade. In
some houses, drain tiles were laid around the
foundation with a sump pump in the basement, and
ground water was pumped into the sanitary sewer
system.
In 1957 through 1961, the rainfall averaged 35.7
inches per year, or 7.3 inches per year above normal
and double the average for the preceding five years
when the sewers were built. In 1957 the first reports
of sewer problems in the area came to the attention
of city officials. Residents in this area began to
complain of sewage backing up into basements.
Sewers in the area had been constructed in
easements along the rear yards. By 1959 cavities
began to appear in the rear yards over house sewers
and public sewers. These cavities were checked, and
the sewers Were discovered to be leaking and allowing
ground water and soil to enter the sewer system.
Nearly all leaks were through joints; very few were
caused by cracked pipe. The sewer lines were repaired
as each cavity was reported. Many were reported in
1959,1960, and 1961.
Investigations in 1957 and 1958 indicated that
infiltration was entering the sewer system through the
tops of the manholes between the rim and the cover,
and that some property owners were lifting the covers
and allowing ponded water in the back yards to enter
the sanitary sewer system. A program of raising the
tops of the manholes was initiated to stop this source
of infiltration.
In March 1961, city officials met with the
Southwest Civic Council to outline the following
cause of sewer flooding:
1. Infiltration into the joints of building sewers
and public sanitary sewers;
2. Inflow from foundation drains connected to
sanitary sewer systems;
3. Flat topography and high water table
elevation;
4. Inadequacy in storm water facilities in the
area;
5. Lots in the area were not graded to drain to
the street, resulting in ponding in the back
yards;
6. Property owners were opening manholes,
allowing surface waters to flow into the
sewer system;
7. Back pressure in the manholes may have
caused the joints to become defective, and
8. The home builders failed to provide any
backwater devices to protect the homes in
the area.
It was agreed that the city should:
1. Maintain continual inspections of the area to
find breaks or leaks in the sanitary sewer
system or house connections;
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2. Study the need for more storm water
facilities;
3. Require more rigid regulations relative to
building sewer drains, and
4. Provide additional main or interceptor
capacity. Property owners should install
backwater devices.
Following the meeting, city officials decided to
(1) make a house-to-house canvas of the area to seek
out other possible illegal connections and explain to
property owners the reasons for not draining surface
water into the sanitary sewer system, particularly
through manholes; (2) smoke-test the sewers and
observe the locations where smoke escaped for clues
to the points where infiltration occurs; (3) install two
observation wells to determine and record the ground
water level.
Approximately half of the area was tested with
smoke bombs during the summer of 1961. Leaks
were detected in 30 of the sewer lines, but were not
repaired pending a determination of the problem's
scope.
In September 1961, the specifications for house
sewers were changed in areas where ground water was
encountered. Concrete encasements became a
requirement in these areas.
In September 1961, the city began evaluating the
possibility of using closed-circuit television to
investigate the sewer problem. In a subsequent study,
63 leaks, were found and these were repaired. Sixty
percent of the leaks were found to be in house lines.
Stripes were painted on 57 manholes for the purpose
of recording high water in the sewer after a rain.
Many failures in the house lines constructed of
bituminous fiber pipe occurred; as each was replaced
with other pipe the problem was relieved. The city
engineer estimated that about 60 percent of the
infiltration was entering the system through house
lines, and that considerable improvement had resulted
from replacement of defective lines. The major
conclusion of the consulting engineer was that the
infiltration resulted from many small leaks and there
were few or no major leaks in the system. The
building sewers were considered to be a major
contributing source of extraneous waters. Ultimately
it was deemed feasible to construct additional
interceptor capacity to relieve the flooding problems.
Winnipeg, Canada
The Metropolitan Corporation of Greater
Winnipeg, Waterworks and Waste Disposal Division,
and the City of Winnipeg have conducted numerous
investigations during the past few years into the
problems of infiltration and combined sewer systems
in the metropolitan area. In September 1969, a report
reviewed the problems of the Rosser area in
northwest Winnipeg.
In 1968, a sewer system for this area was
installed. Inspection of the sewers after completion
indicated that the quality of construction was such
that considerable infiltration could be expected. To
determine the extent of infiltration, a chart recorder
was installed at the pumping station to provide a
record of the running time of the pumps. A
comparison was made with the average daily water
consumption in the area. The following ratios of
quantity of sewage flows to the quantity of water
delivered was as follows: minimum flow — 3.5:1;
average dry weather — 5.0:1; maximum summer heavy
rain — 19.4:1, and maximum spring runoff —153.1:1.
Later in 1968, an inspection was made of the
sewers in the area, and television was used on sewers
10 inches in diameter and larger, representing 41
percent of the total tested for infiltration.
As a result of these inspections large flows of
water were found to be entering almost all the
manholes between the concrete rings. In addition
there were 10 locations where pipe joint rubber rings
were protruding into the sewer—indicating poor
attention to the watertightness of the sewer. The
results of the infiltration test confirmed that the
installation did not meet required standards for
sanitary sewers.
The report recommended that:
1. The city should adopt strict specifications on
infiltration allowances and follow up with
pressure tests on complete jobs before
acceptance.
2. Consideration should be given to correcting
the existing system with grouting of
manholes where leakage exists and pressure
grouting of pipe joints where rings are
misplaced.
3. Grades should be more carefully controlled
on sanitary sewer lines to prevent future
blockage problems.
Another report on the general problem
throughout the Metro area pointed out that the
sources of "extraneous flow" — additions, over and
above normal domestic sewage allowances — may be
from downspout, driveway, patio, or weeping-tile
connections to the sanitary lines, or any combination
thereof. Storm sewer cross-connections and street
drainage into sanitary manholes also may contribute
to this extraneous flow experienced during storms.
The report stated that Metro must adapt its
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system to live with infiltration conditions to a degree
which reasonably can be controlled, and that it must
revise sewer design criteria to include an allowance
for a reasonable amount of extraneous flow (over and
above the infiltration allowance now included).
Yakima, Washington
In December 1961, the city had a consulting firm
conduct a preliminary investigation to establish sewer
design criteria and prepare preliminary designs for
improvements and additions to the sewage collection
and treatment facilities. This study was to include
investigation of the infiltration problems in the
sanitary sewer system and establish a program for
reducing infiltration where economically justified.
The report on these studies said the effect of
excessive infiltration is to create additional flow that
reduces the sewers' capacity for existing or future
sanitary sewage. The flow also adds to the treatment
facilities' loads and limits their ability to treat the
sewage adequately. This excessive infiltration often
necessitates -earlier expansion of both the sewage
collection system and the treatment plant.
Surface or storm water is another source of flow
which, in many systems, was not intended to enter
the sewer and exceeds the design sewage flow. This
additional flow enters the sanitary sewer in Yakima
through roof and foundation drains, holes, manhole
covers, and cross-connections between the storm and
sanitary sewer systems.
The report described exfiltration as a source of
pollution in the ground water table. It urged
reduction of exfiltration effects by proper
maintenance.
The flow at the treatment plant caused by
infiltration ranged up to an estimated 15 mgd during
the summer months. Although it is common to
expect variation in sewage flow between high and low
ground water periods, the flow from infiltration
rarely represents 70 to 80 percent of the total flow
over extended periods, as in the Yakima situation.
The records in 1962 indicated that total precipitation
during the months of high infiltration, May through
September, was only 1.8 inches and that no rain
occurred during the period just prior to recording the
peak flow. Therefore, the entrance of surface water
was not considered a major factor in the Yakima
sewage collection system, and the infiltration of
ground water is the primary contributor to the high
flows recorded at the treatment plant.
Treatment plant flow records were found to
indicate a definite increase in flow rates when the
municipal irrigation system is turned on in the spring,
and also a definite decrease when the irrigation
system is shut down in the fall. In 1961, the flow at
the treatment plant increased approximately 3.6 mgd
within four days after the irrigation system was
activated. In 1962, the older portion of the irrigation
system was activated on March 26; the minimum flow
at the treatment plant increased 4.2 mgd within five
days and fell approximately 3 mgd in three days,
when the irrigation system was shut down for repairs.
The consultants recommended that the city:
1. Include in the annual sewer budget $25,000
per year over the next 10 years for
infiltration correction by repairing and
replacing existent sewers during the winter
months;
2. Initiate the annual infiltration correction
program by retaining a sewer grouting
contractor to grout the sewer lines internally
in the West Mead System Project No. 1;
3. Continue the current photographic
inspection program of the sewer system until
the entire system is recorded on film;
4. Maintain comprehensive logs of the firmed
sewers to develop a list of repair, grouting,
and reconstruction projects which can be
scheduled annually through the next 10-year
period, and
5. Require rigid inspection of all future sewer
construction to assure minimum infiltration.
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SECTION 7
BUILDING SEWERS
The building sewer connects the structure served
with the main public sewer. The portion of the
building sewer between the structure and «the
property line constitutes one part of the connection.
The portion between the property line and the public
sewer in the street completes the connection. There is
a loss of control governing the installation and
inspection of these sewers.
Reference is made to these two portions of
building sewers because the separate parts commonly
are 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 is often
interpreted as an extension of the in-structure
facilities; it ordinarily is installed under plumbing or
building code regulations, and tested and approved by
plumbing officials or building inspectors. The section
of the building sewer between the property line and
the street sewer, including the connection thereto,
usually is installed under sewer rules, and inspection
and approval are within the purview of public works
or sewer officials.
One exception to this rule of split authority
often occurs in the case of industrial wastes
connections. Because of the possible effect of such
wastes on sewer structures and treatment facilities,
the entire length of these building sewers may be
supervised by sewer officials. In this way they better
control such connections and the introduction of
wastes, when these are ruled to be amenable to sewer
transportation and treatment.
The problems inherent to the divided authority
mentioned above were explored during the course of
the studies.
Building sewers contribute a large portion of the
overall infiltration and inflow volumes carried by
separate sanitary and combined sewer systems.
The multiplicity of these lines in any given
stretch of collection sewers in heavily built-up urban
areas, and the fact that each connection line has two
physical connection points — one at the building line
and the other at the junction with the public
sewer - all contribute to the potential entry of
infiltration water into sewer systems.
Building sewers may be the discharge point for
inflow connections from roof drains, cellar and
foundation drains, basement or subcellar sump lines,
or "clean water" commercial and industrial effluent
lines.
In terms of infiltration, the relationship between
the total length of building sewers and the length of
street sewers receiving building flows is often equal to
or greater than street sewer length. For example, lots
with 50-foot street frontage provide four building
connection sewers per side of the street, or eight per
200 feet of block length. If the average building sewer
is 25 feet long to the street line, including sidewalk
width, grass plot, and carriageway, the total length of
these lines will be equal to the length of the street
sewer.
A survey of infiltration and inflow control
practices of state and provincial water pollution
control agencies disclosed opinions that poorly made
house connections, illicit house connections, poor
house sewer taps, and poor house sewer construction
practices were among the known sources of excessive
infiltration into sewer systems.
While the opinion is widely held that building
sewers contribute a large amount of the total
infiltration flows carried by sewer systems, the exact
role of these connection lines has not been
determined with sufficient certainty to permit
drawing definitive conclusions. This is clearly shown
in Table 32, National Field Investigations - Estimated
Percentage of Total Infiltration Attributed to
Building Sewers. The twenty-six of the representative
jurisdictional sewer systems investigated by
on-the-site interviewers during the course of the
national investigation are covered in the tabulation.
Estimates of the percentage of infiltration in the total
system attributable to building sewers ranged so
widely that the validity of any conclusions drawn
from these data is subject to some question.
Percentage effects ranged from 95 percent at New
Orleans, Louisiana, and 75 percent at Baltimore,
Maryland, to only 1 percent at Ft. Lauderdale,
Florida, 2 percent at Watsonville, California, and 3
percent at Washington, D.C. In Nassau County, New
York, the interviewer was informed that infiltration
through building sewer connections was "negligible."
The in-depth investigations carried out in the 26
representative jurisdictional systems, with
interviewers attempting to obtain all available
information, disclosed that nine systems included in
the tabulation in Table 32 had made no estimates of
75
-------
the effect of building sewer infiltration on the total
flow of extraneous waters carried by their sewer
systems.
TABLE 32
NATIONAL FIELD INVESTIGATION
ESTIMATED PERCENTAGE OF TOTAL
INFILTRATION ATTRIBUTED TO
BUILDING SEWERS
City
Baltimore, Maryland
Bloomington, Minnesota
Dallas, Texas
Denver, Colorado
Ft. Lauderdale, Florida
Jacksonville, Florida
Knoxville, Tennessee
Milwaukee, Wisconsin
Nassau County, L.I., N.Y.
New Orleans, Louisiana
New Providence, N.J.
Princeton, N.J.
San Jose, California
Savannah, Georgia
Washington, District of
Columbia
Washington, Suburban
Sanitary Commission
Watsonville, California
Yakima, Washington
Estimated Percentage
75%
25%
50%
High — No estimate
1%
20%
30%
65%
Negligible
95%
0%
60%
60%
35%
3%
40%
2%
40%
Further efforts to obtain specific estimates on
this subject from state and provincial water pollution
control agencies, consulting engineers, and other
involved persons and entities proved relatively
unproductive. In Figure 12, Infiltration and Inflow
from Building Sewer Connections, are photographs of
typical poorly made field connections, allowing
infiltration to occur.
Computation of Building Sewer Infiltration
An effort was made to derive guidelines on the
extent to which infiltration could be attributed to
building sewers in a typical sewer system. The
theoretical computation is shown in Table 33,
Estimate of Relative Amount of Infiltration from
Building Sewers. This computation is based on the
two assumptions that: (1) the total length of building
sewers in the section of the street sewer used in the
computation is twice that of the street sewer, and (2)
the building sewers have the same construction
quality, in terms of tightness, as the street sewer
system.
The sample calculation indicates that, under such
conditions, building sewer infiltration could account
for 38 percent of the total infiltration into the entire
TABLE 33
THEORETICAL COMPUTATION OF ESTIMATE
OF RELATIVE AMOUNT OF INFILTRATION
FROM BUILDING SEWERS
ASSUMPTIONS:
1. Total building sewer length is approximately
two times the total main sewer length.
2. Average building sewer diameter is 6 inches.
3. Average main sewer diameter is 12 inches.
4. Infiltration through the sewer joint is
proportional to the diameter of the pipe.
5. The average ground water head on the
building sewer is two feet (2 feet).
6. The average ground water head on the main
sewer is five feet (5 feet).
7. Infiltration occurs at the joints, and the
number of joints are assumed to be proportional to
the length of the sewer line.
Infiltration, therefore, can be expressed by the
following equation:
I a D •*/ H L
where:
I = Infiltration
D = Diameter of pipe
H = Ground water head on pipe
L = Length of pipe
Ig = Building sewer infiltration
Calculations:
(equation 1)
= T
B
JM
(equation 2)
= Total infiltration
= Infiltration from building sewer
= Infiltration from main sewers
~2~ (2L) Substituting in equation 1
(Building sewer)
la 12 i/ 5 L Substituting in equation 1
(Main sewer lines)
The relative amount of infiltration from building
sewers is, therefore, estimated as follows:
lr,(%)= ID X100
(2U
X100
)= 38%
76
-------
FIGURE 12
__^ . . . ^^
Courtesy: Underwater Tcle-Kquip., Ltd.
INFILTRATION AND INFLOW FROM BUILDING SEWER CONNECTIONS
-------
sewer system. The computed percentage will vary
with the street frontage of building lots and the width
of the street from building lines to street sewer lines.
In the City of Baltimore, Maryland, for example,
the total length of building sewers connected to a
specific section of the "old city" street sewer is
influenced by the famous "row house" type of
construction there. Long stretches of homes are built
with common walls and no yard areas between the
individual buildings, thus increasing the number of
house connections per block. Significantly it was
estimated in Baltimore that 75 percent of the total
infiltration into the city sewers resulted from building
sewers.
A theoretical computation of Baltimore building
sewer length, in relation to street sewer length, was
made for the row-houses section of Baltimore, as
shown below.
Assume: House connection to be 25 feet long.
House frontages to be 20 feet wide.
A block length to be 500 feet.
The number of house connections for both
sides of the street block would be 500 divided
by 20, or 25, which multiplied by two equals
50.
The total length of building sewer lines would be
25x50, or 1,256 feet.
Therefore, the proportional total length of
building sewers would be 1,256 divided by 550
(including cross street right-of-way), or about
two and one half times the total length of street
sewers into which they are connected.
This would make the building sewer infiltration
potential 71 percent of the total infiltration into the
sewer system, assuming that the infiltration rates are
equivalent inasmuch as the quality of sewer pipe and
joints are about the same. The row-house construction
exists only in the older city and the percentage length
of building sewers would be less in outlying areas
where building lots have wider street frontages,
although the length of the_ average building sewer
would be increased for homes with a set-back from
the property line.
Pipe and Joints for Building Sewers
The ability of building sewers to exclude
infiltration water depends on the type of pipe used
and the effectiveness of jointing procedures. In
recognition of the importance of these materials, the
surveys to determine jurisdictional sewer system
practices made every effort to explore the policies
and practices involving pipe and joints used for
building sewers.
Investigations in the'26 representative systems
laid open the broadly held opinion that recent
developments in jointing materials have brought a
marked reduction in infiltration attributable to
building sewers. Jurisdiction officials and sewer
contractors referred to the use of "O" ring-type joints
as a great improvement in building sewer
construction. Some jurisdictions reported they have
undertaken programs to replace defective connecting
sewers, including separation of foundation and
basement drains, and roof leaders from these building
conduits. The problems involved in excluding these
inflow waters into building sewers, and thence into
public sewer systems, are discussed in another section
of this report.
Table 34, National Field Investigation - Summary
of Permitted Pipe Materials and Joints in Building
Sewers, lists the types of pipe and joints permitted
in the 26 jurisdictions investigated in the national
research project.
Consulting engineers were asked to list the pipe
materials and joints that they specified to control
infiltration into building sewers. The 66 replies are
tabulated in Table 35, Consulting Engineers
Survey — Pipe Material Specified for Building Sewers.
TABLE 35
CONSULTING ENGINEERS SURVEY
PIPE MATERIAL SPECIFIED
FOR BUILDING SEWERS
Vitrified Clay 49
Cast Iron 44
Asbestos Cement 34
Plastic 18
Bituminous Fiber 4
Concrete . 2
Obviously some consultants specify more than
one material and, in fact, more than one type of joint
on the same pipe material. The listing on joint usage
is contained in Table 36, Consulting Engineers
Survey - Joints Specified for Building Sewers.
Compression gaskets were listed as "0" Ring, Molded
PVC, and Rubber Gasket.
TABLE 36
CONSULTING ENGINEERS SURVEY
JOINTS SPECIFIED FOR BUILDING SEWERS
"O" Ring 74
Molded PVC 32
Rubber Gasket 16
Solvent Weld 13
Lead 10
78
-------
TABLE 34
NATIONAL FIELD INVESTIGATIONS
SUMMARY OF PERMITTED PIPE MATERIALS
AND JOINTS IN BUILDING SEWERS
City
Baltimore, Maryland
Bloomington, Minnesota
Dallas, Texas
Denver, Colorado
Ft. Lauderdale, Florida
Hot Springs, Arkansas
Indianapolis, Indiana
Jacksonville, Florida
Janesville, Wisconsin
Knoxville, Tennessee
Milwaukee, Wisconsin
Nassau County, N.Y.
New Orleans, Louisiana
New Providence, N.J.
Oakland County, Michigan
Materials
Cast Iron
Vitrified Clay
Concrete
Asbestos Cement
Cast Iron
Asbestos Cement
Cast Iron
Vitrified Clay
Cast Iron
Vitrified Clay
Concrete
Cast Iron
Vitrified Clay
Plastic
Bituminized Fiber
Cast Iron
Vitrified Clay
Concrete
Plastic
Cast Iron
Cast Iron
Vitrified Clay
Cast Iron
Asbestos Cement
Bituminized Fibre
Cast Iron
Vitrified Clay
Concrete
Asbestos Cement
Cast Iron
Vitrified Clay
Concrete
Asbestos Cement
Cast Iron
Vitrified Clay
Cast Iron
Cast Iron
Asbestos Cement
Cast Iron
Vitrified Clay
Joints
(1)
"O" Ring, Poured
"O" Ring
"O" Ring
"0" Ring
"O" Ring, Lead
"O" Ring
Lead
"O" Ring
Neoprene, Slip Joint
Neoprene
Neoprene, Mortar
Rubber gasket. Lead
Rubber gasket, Plastisol
Chemical weld. Rubber gasket
Slip type
"O" Ring, lead
ASTM C-425
"0" Ring
Chemical weld
Mechanical
ASTM C-425
Lead
Mastic, Wedgelock
"O" Ring, Lead
"O" Ring
Friction
Lead
ASTM C-425
Rubber ring
"O" Ring
"O" Ring, Lead
Cement, PVC, "O" Ring
Cement "0" Ring
"O" Ring
Lead, Mechanical
Hot Asphalt, "O" Ring
Lead, Compression gasket
Poured lead
"O" Ring
" 'Type of joints is as listed by reporting agency.
79
-------
TABLE 34 (Continued)
Omaha, Nebraska
Princeton, N.J.
Richmond, Virginia
San Jose, California
Savannah, Georgia
Suburban Sanitary Com.,
Washington, D.C.
Toronto, Canada
Washington, District
of Columbia
Watsonville, California
Winnipeg, Canada
Yakima, Washington
Asbestos Cement
Cast Iron
Vitrified Clay
Asbestos Cement
Vitrified Clay
Cast Iron
Cast Iron
Vitrified Clay
Cast Iron
Asbestos Cement
Cast Iron
Asbestos Cement
Cast Iron
Asbestos Cement
Cast Iron
Concrete
Asbestos Cement
Vitrified Clay
Vitrified Clay
Cast Iron
Asbestos Cement
Cast Iron
Vitrified Clay
Asbestos Cement
Bituminized Fiber
Cast Iron
Vitrified Clay
Asbestos Cement
Cast Iron
Vitrified Clay
Concrete
"O" Ring
Lead
Hot Asphalt, "O" Ring
"O" Ring
"O" Ring
Lead
Lead
"O" Ring
Lead, "O" Ring
"O" Ring
Stainless collar
"O" Ring
Poured lead
"O" Ring
"O" Ring
"O" Ring
"O" Ring, Bituminous
Poured lead
"Sleeve and Cement"
"O" Ring, Plastisol
"O" Ring
Caulked, Lead
Cement, "O" Ring
"O" Ring
Lead
"O" Ring
"O" Ring
Some of these jointing materials relate to
particular pipes, and therefore their use would
depend on the popularity of that pipe. In general the
present selection of pipe and joints for building
sewers closely parallels the usage for street and lateral
sewers. Compression gaskets have improved the
infiltration resistance of all types of pipe. However,
cast iron pipe is in greater use in building sewers than
in larger street sewers.
In the more extensive statistical survey of
jurisdictions, the percentage distribution of pipe
materials and joint usage was very similar to that
specified by the consultants. Because of the larger
sampling, however, a number of different materials
such as wood and copper were reported. Table 37,
National Statistical Survey - Building Sewer Pipe and
Joint Materials Specified, lists the results according to
regions and population groups.
The high incidence of cast iron again is shown in
this national summary. The prevalence reflects not
only the desire for strength and root resistance but
also the fact that building sewers traditionally have
been installed by plumbers using cast iron and poured
joints for water lines and internal plumbing and soil
pipes.
Proper choice of sewer pipe to minimize greatly
or eliminate the large percentage of infiltration
attributable to poorly constructed building sewers is
becoming a more widely recognized need, as
indicated in the above discussions and the statistical
survey findings.
Bloomington, Minnesota, has demonstrated this
80
-------
00
TABLE 37
NATIONAL STATISTICAL SURVEY
BUILDING SEWER PIPE AND JOINT MATERIALS SPECIFIED
Region
East
Sub-
Total
Soutti
Sub-
Tolat
MMwest
Sub-
Total
Poputatuon
Over 200,000
100,000-199,999
20,000- 99.999
10,000- 19.990
Under 10,000
Over 200,000
100,000-199,909
20.000- 00,999
10,000- 19999
Under 10,000
Over 200.0OO
100,000-199.399
20.000- 99.999
10,000- 19,909
Under 10,000
Southwest Over 200,000
Sub-
Total
West
Sub-
Total
Canada
Sub-
Total
Totals
Totals
100,000-100,909
20.00O 99^99
10,000- 00,009
Under 10,000
Over 200,000
100,000-199,999
20,000- 00,099
10.0OO 19,999
Under 10,000
Over 200 ,000
100,000-199^99
20,000- 99,990
10,000- 10,099
Under 10,000
Over 200,000
100,000-199,099
20,000- 00,099
10,000- 19,990
Under 10,000
Vitrified
day
5
8
IS
4
1
31
S
2
7
4
-
18
4
4
14
7
2
31
6
1
10
4
1
22
7
7
27
0
2
52
2
1
S
2
2
12
29
21
78
30
8
166
Atbnu*
Cement
2
2
7
2
-
13
1
-
4
3
-
8
_
2
3
2
-
7
4
1
8
1
-
12
4
4
17
0
2
36
_
2
6
2
2
12
11
11
43
10
4
88
Plastic
2
-
3
1
_
6
„
_
1
1
_
2
_
-
1
_
_
1
_
1
3
1
-
5
1
1
-
-
-
2
_
-
-
-
-
-
3
2
8
3
-
16
Cast
Iron
S
5
18
4
1
33
4
3
10
4
_
21
4
5
12
5
2
28
8
2
10
4
2
25
6
6
22
9
2
45
2
1
4
-
-
7
27
22
76
26
7
158
Rein.
Pipe Material*
BrUrminou*
Concrete Fibre Copper
1
_
-
-
-
1
_
-
_
-
-
-
_
-
_
-
-
-
_
-
-
-
-
-
_
-
-
-
-
-
_
-
-
-
-
-
1
-
-
-
-
1
2
1
2 1
1
-
8 1
_ _
1
3
1
_
5
_ _
-
1
1
1
3
_ _
-
6
3
1 —
10
1
1
7
-
1
10
_
-
2
-
- -
2
3
3
21 1
8
3
38 1
Wood
Trim Concrete Stave Plastic
_
_ - _ _
_
1 1 - -
_
1 1 - -
2
_
5
- 2 - -
_
0
_ _ _ _
_ _
- 2 - -
- 1 - -
_ _ _ _
3 - -
2
_
- 1 - -
_
_
- 1 - 2
3
- 2 - -
4 - -
3 1 1
_ _ _
12 1 1
_ _ _
_
_ _
- 1 - -
_
1
- 5 - 2
2
12
1811
-
1 27 1 3
Joina
Brluminout
S
2
4
2
_
13
1
1
2
1
_
5
_
1
6
1
1
9
3
-
6
3
1
13
2
_
5
_
1
8
_
1
3
1
2
7
11
5
28
8
5
55
Mortar
2
3
S
1
_
11
1
3
1
2
_
7
1
3
3
1
_
8
2
_
3
3
1
9
2
2
8
2
1
15
2
-
4
1
1
8
10
11
24
10
3
57
Poured
3
4
11
3
1
22
2
4
7
3
_
16
2
4
9
3
1
19
5
1
7
1
2
16
3
1
9
4
_
17
2
-
1
-
-
3
10
14
44
14
4
92
Chemical
_
-
-
-
-
-
_
_
_
_
_
-
_
-
_
_
1
1
_
-
-
-
-
-
_
1
_
-
_
1
_
-
-
-
-
-
_
1
-
-
1
2
Rubber
Rm,
7
7
19
4
1
38
5
6
10
3
_
24
2
4
13
7
2
23
5
1
10
4
1
21
6
7
26
11
2
52
2
2
7
3
2
16
27
27
85
32
8
179
ftasOe
_
_
2
1
_
3
1
1
2
2
_
6
3
4
6
2
1
18
5
_
7
2
_
14
4
3
12
4
1
24
_
-
1
-
-
1
13
8
30
11
2
64
No
Anewer
_
_
1
1
_
2
_
_
_
1
_
1
_
_
_
_
_
-
_
_
_
_
_
-
_
_
_
_
_
-
_
-
-
-
-
-
_
-
1
2
-
3
-------
concern by adopting specifications covering such
building sewers. The criteria stipulate not only pipe
materials but jointing practices and property line
sewer stubbing procedures; these will, in the opinion
of the city officials, minimize the role of building
sewers as a major source of infiltration. Excerpts
from these specifications are given in Table 38,
Excerpts from Requirements for Building Sewers,
Bloomington, Minnesota.
TABLE 38
EXCERPTS FROM REQUIREMENTS FOR
BUILDING SEWERS
BLOOMINGTON, MINNESOTA
I. Sewer Services
A. Residential
1. Materials
a. Residential sewer services shall be of
extra heavy spun cast iron pipe, not less
than 4 inches in size, with a neoprene
gasketed, or poured lead joint.
b. Asbestos-cement pipe may be used
only with open trench construction and
granular bedding.
c. Adaptors shall be used at property
line sewer stub and shall be of a type
approved by the Utility Supervisor or
Water/Sewer Engineer.
B. Commercial and Industrial
1. Materials
a. Vitrified clay pipe with a joint
approved by the Utility Supervisor or
Water/Sewer Engineer, or extra heavy
cast iron pipe with neoprene gasketed or
hot lead joints will be used.
b. Asbestos-cement pipe may be used
only with open trench construction and
granular bedding.
The investigations of the 26 representative
jurisdictions disclosed that many design engineers,
municipal sewer officials, and contractors are
concerned over the shearing action on building sewers
at points where they cross the main street sewer
trench. This shearing "results from uneven settling in
both lines, particularly where the street sewer is laid
in an extremely deep trench and the building sewer is
laid in a shallow trench.
Various types of construction have been
proposed to counteract this condition. Where
building sewers and street sewers meet at the same
elevation, concrete encasement of the building sewer
and some form of support for the "Y" connection
may be used. When the main street sewer is laid in a
deep trench and a drop connection must be provided
for the building sewer, the entire riser may be encased
in concrete, or at least the "T" connection at the
main should be sleeved with concrete. The
suggestions made during the course of the national
investigations proved that the vital connection
between building sewers and street sewers is receiving
attention and that improved construction methods
will be used in the future. These improvements will
include greater attention to the backfilling and
compaction of trenches.
When a new sewer is being constructed in an
undeveloped area, it is common practice to "stub
out" "Y's" and "T's" to allow for connection of
building* sewers between abutting properties.
Specifications require that these fittings be properly
plugged and caulked to prevent infiltration prior to
the time they are used to connect building sewers to
the street sewer. If these stub lines are improperly
plugged, they can be the source of excessive amounts
of ground water infiltration.
When old buildings are demolished and sewer
connections are left unused, the connections should
be plugged at the building line until linked to a new
building — or totally eliminated if no new building
connection is to be made. Unplugged old building
connections were reported to be the source of as
much infiltration flows as unplugged street sewer
stubs.
Divided Authority Over Building Sewer Installation
Reference has been made to the impact of
divided authority over building sewer installations,
particularly on the effectiveness of construction and
the consequent infiltration conditions. As part of the
field investigations, emphasis was placed on the
question of which local agencies maintain control
over building sewers.
Of the 26 jurisdictions listed in Table 39,
National Field Investigation - Summary of
Specifications, Installation and Inspection Authority,
19 indicated that their building sewer installations
were carried out exclusively under a split of
responsibility between housing and plumbing officials
and sewer officials. At Dallas, Texas, a single
authority holds responsibility for the entire building
sewer—not because a single local official covers the
two separate segments of a building sewer but
because a single agency, the water utility department,
encompasses both plumbing and sewer functions.
Three other jurisdictions reported similar total
82
-------
TABLE 39
NATIONAL FIELD INVESTIGATIONS
SUMMARY OF SPECIFICATION, INSTALLATION AND
INSPECTION AUTHORITY OVER BUILDING SEWERS
City
Baltimore,
Maryland
Type of
Jurisdiction
Split Authority
Bloomington,
Minnesota
Dallas,
Texas
Single Authority
Single Authority
Denver,
Colorado
District of Columbia,
Washington
Ft. Lauderdale,
Florida
Hot Springs,
Arkansas
Indianapolis,
Indiana
Jacksonville,
Florida
Janesville,
Wisconsin
Single Authority
Split Authority
Split Authority
Split Authority
Split Authority
Split Authority
Split Authority
Explanation
As of 1968 building sewers from building to property
line are specified, installed and inspected under the
jurisdiction of the Department of Housing and
Community Development. Plumbers licensed by the
state lay the line from the building to the property line.
"Drain Layers" licensed by the Department of Public
Works lay the line from the property to the street sewer.
The latter is inspected by the Department of Public
Works. Permits are required for any connection to the
street sewer.
Public Works Department has complete jurisdiction over
building sewer connections on both private and public
property.
Water Utility Department has jurisdiction of public
construction. Plumbing Inspector under this agency.
Considerable interest in house connection problems.
Department personnel make tap or connection to
municipal sewer. Water test to property line.
Chief waste water control engineer of the Waste Water
Control Agency has full responsiblity for this activity.
Engineering Division inspects sewers. Inspection Division
inspects house connections. Completely separate
operations.
Building Department has jurisdiction on private
property. City Engineer controls public right-of-way.
Plumbing Inspector has jurisdiction over building sewer
connections, but inspection is not performed.
Plumbing Inspector as a part of the building department
has jurisdiction over building connections.
Building Inspector is responsible for this activity on
private land while the City Engineer exercises control
over public part of connection on right-of-way or street.
Plumbing Inspector has jurisdiction from the building to
the property line. The City Engineer has jurisdiction
from the property line to the main sewer.
83
-------
TABLE 39 (Continued)
City
Knoxville,
Tennessee
Milwaukee,
Wisconsin
Type of
Jurisdiction
Split Authority
Split Authority
Nassau County,
New York
Split Authority
New Orleans,
Louisiana
Single Authority
Explanation
Activity comes under plumbing code which specifies
that plumber makes connection at property line.
Plumbing Inspector is responsible for this connection.
City Engineer is responsible for balance.
Plumbing Inspection Division of the Building
Department has jurisdiction on private property. The
City Engineer has jurisdiction over the portion on public
property. The Building Department and Engineering
Department coordinate their efforts in known
"backwater problem" areas.
County issues permit for the total connection. The
County specifications cover connection from the main
sewer to the "curb"line. Local building department
issues permit from the "curb" line to the building.
Inspection responsibility is divided the same way.
Sewerage and Water Board exercises complete
jurisdiction over the building sewer and the Plumbing
Department performs the work.
New Providence,
New Jersey
Split Authority to
some extent
Municipal engineer is in charge of sewer construction
and house connections to within 5 feet of foundation of
house.
Oakland County,
Michigan
Princeton,
New Jersey
Split Authority
Split Authority in
some cases
County Department of Public Works issues rules and
regulations. Local unit of government provides any
inspection and testing.
Township and Borough are members of Sewer Operating
Committee which maintains plants, lift stations, and
main sewers. Township Engineer inspects construction in
his area, SOC inspects in Borough and on trunks. SOC,
Township Engineer, or Borough Engineer may all
become involved in house connection inspections
although house connections are not tested.
Richmond,
Virginia
San Jose,
California
Split Authority
Split Authority
City Engineer has jurisdiction from the main sewer to
the property line. The Plumbing Inspector (Department
of Public Safety) has jurisdiction from property line to
building.
City Engineer has jurisdiction from the mam sewer to
the property line. The Plumbing Inspector (Building
Department) has jurisdiction from property line to
building.
84
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TABLE 39 (Continued
City
Savannah,
Georgia
Suburban Sanitary
Commission,
Washington, D. C.
Toronto,
Canada
Watsonville,
California
Winnipeg,
Canada
Yakima,
Washington
Type of
Jurisdiction
Single Authority
Single Authority
Split Authority
Single Authority
Split Authority in
some instances
Split Authority
Explanation
Plumbing Inspector is only official charged with this
activity.
Commission exercises complete control over sewer
installation and all plumbing code activities.
City Works Department has jurisdiction on public
property. Plumbing Inspector has jurisdiction on private
property.
City Engineer has jurisdiction on public property.
Plumbing Inspector (Building Department) has
jurisdiction on private property.
In the Metropolitan Area most City Engineers have
authority over building connections.
Plumbing Inspector under the Planning and Community
Development Department has jurisdiction over building
connections.
control by a single agency. Another two indicated
that split authority had been mitigated by joint
actions.
In the case of Princeton, New Jersey, the
problem of divided authority has been partially
overcome by creation of a Sewer Operating
Committee in which township and borough engineers
hold membership. These engineering officials are
involved in house connection inspections. At New
Providence, New Jersey, the municipal engineer is
responsible for sewer construction and house
connections to within 5 feet of the building
foundation wall.
The 212 jurisdictions covered in the national
statistical survey also were asked how building sewers
are regulated and who inspects them. Table 40,
National Statistical Survey - How Building Sewers
Are Regulated, indicates that 138 municipalities
utilize plumbing codes for this purpose; sewer
ordinances taking second place with 109 jurisdictions.
The regional difference is small; in the East and in the
West, ordinances are used more frequently than
plumbing codes.
The same communities report that plumbing and
building inspectors are used more for building sewer
inspection than any other officials. Only in the East
and West do the engineering inspectors approach or
exceed the building or plumbing inspector in this
function. Table 41, National Statistical Survey—Who
Inspects Building Sewers?, summarizes the responses
by region and population.
All of these survey results point to the fact that
one of the most critical parts of the whole sewer
system, the building sewer, receives the smallest and
least coordinated attention. Laws and codes
themselves are too often vague and, in truth, perhaps
no agency is held responsible for some important
aspect of infiltration and inflow control.
Advisory Committee Survey on Building Sewer
Practices
Twenty-five separate jurisdictions represented on
the Advisory Committee participated in the special
survey on building sewer practices. Thirteen of the
participants reported that the engineering or public
works department specified the types of pipe material
and joints used in these connecting lines, while nine
indicated that the plumbing or building department
bore this responsibility. Three reported that the
responsibility was split between the two departments.
As to inspection and testing of building sewers, the
plumbing or building department was involved in 13
jurisdictions and the engineering department in seven,
while responsibility for this operation was split in
85
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TABLE 40
NATIONAL STATISTICAL SURVEY
HOW BUILDING SEWERS ARE REGULATED*11
Question: Are House Sewer Connections
Regulated - If so - By What?
Region
East
Sub-Total
South
Sub-Total
Midwest
Sub-Total
Southwest
Sub-Total
West
Population
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Sewer
Ordinance
Sewer
Rules
Building
Code
Plumbing
Code
Sub-Total
3
3
14
2
0
22
3
2
5
1
0
11
2
2
10
4
1
19
2
1
5
2
2
12
3
7
21
7
2
40
4
3
8
1
0
16
1
1
4
0
0
6
3
0
4
1
0
8
1
0
2
0
0
3
2
3
4
2
0
11
4
1
7
0
0
12
2
1
3
0
0
6
2
1
5
0
1
9
1
0
4
3
0
8
1
2
12
7
0
22
4
6
15
3
1
29
5
2
11
3
0
21
2
3
13
5
1
24
6
1
6
3
0
16
6
4
19
5
2
36
' 'Many agencies gave more than one response.
86
-------
TABLE 40 (Continued)
Region
Canada
Sub-Total
Totals
Population
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Sewer
Ordinance
1
2
1
0
1
5
14
17
56
16
6
Total
five. One community reported that its public works
department actually laid the entire house sewer to the
foundation, thus maintaining complete control. Most
jurisdictions reported that no testing of any
consequence ever was made on building sewers.
Sixteen jurisdictions reported no difficulty in
making sewer connections to the building sewers,
while seven had experienced problems.
When asked if infiltration into building sewers
was an important factor, 18 said "yes" and seven said
"no." Four jurisdictions called particular attention to
the role of the building sewer in conducting
foundation drains into sewer systems. One member of
the project Steering Committee made the following
statement: "In my opinion, infiltration into building
sewers is the most important factor in the overall
109
Sewer
Rules
1
1
1
1
1
5
12
8
23
5
1
49
Building
Code
0
0
1
1
1
3
10
5
32
11
2
60
Plumbing
Code
2
1
6
2
1
12
25
17
70
21
5
138
problem. I estimate that the total footage of building
sewers is four times that of the public sewer system
for most communities. Where ground water tables are
high and infiltration from ground water sources could
be considered proportional to length of the street
sewer and building sewer systems, then it is evident
that leaks in public sewers cause about 20 percent of
the problem and building sewers the remaining 80
percent." Another member of the committee said he
did not feel that infiltration into building sewers in
his area was a major problem, because of the tight
specifications on materials. Obviously, there has been
a great range of experience in this situation, much of
which can be related to specific areas of the country
and the age of the sewer system.
TABLE 41
NATIONAL MUNICIPAL STATISTICAL SURVEY
WHO INSPECTS BUILDING SEWERS?(1)
Region
Population
Inspector
(2)
Question: Is the Construction of House Sewer
Connections Inspected - If so — By Whom?
Building Plumbing Sewer Mun. Eng. Dept. of
Inspector Agency Department Public Wks. Other
East
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Sub-Total
3
1
3
2
1
10
6
4
15
3
0
28
3
1
4
0
0
8
2
2
6
3
1
14
3
2
6
0
0
11
0
0
2
0
0
2
87
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TABLE 41 (Continued)
Region Population
South
Sub-Total
Midwest
Sub Total
Southwest
Sub-Total
West
Sub-Total
Canada
Sub-Total
Totals
Over 200,000
100,000-199,999
10,000- 99,999
Under 10,000
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Over 200,000
100,000-199,999
20,000- 99,999
10,000- 19,999
Under 10,000
Inspector^
0
0
1
0
1
1
0
2
1
0
4
1
1
3
2
1
8
0
0
12
7
2
21
0
0
1
0
0
1
5
2
22
12
4
Building
Inspector
5
2
10
0
21
2
5
12
6
2
27
6
2
8
3
2
21
5
5
16
4
1
31
1
1
4
0
2
8
25
19
65
20
7
Plumbing
Agency
1
1
1
0
3
2
0
0
0
0
2
0
0
0
0
0
0
2
2
6
1
0
19
0
0
1
0
0
1
8
1
12
1
0
Sewer
Department
0
0
1
0
1
0
2
4
2
0
8
0
0
0
0
0
0
2
1
1
1
1
6
1
1
1
0
2
5
5
6
13
6
4
Mun. Eng.
Public Wks.
1
0
0
0
1
2
1
5
1
0
9
1
0
0
0
0
1
2
3
6
4
0
15
0
0
1
3
0
4
9
6
18
8
0
Dept. of
Other
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
2
0
0
3
0
0
0
0
0
0
1
0
4
0
0
Total
45
136
24
34
41
(1)
(2)
Many agencies gave more than one response.
Not otherwise identified.
88
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SECTION 8
ECONOMIC FACTORS IN INFILTRATION AND INFLOW CONTROL
The main responsibility of officials in the
operation and maintenance of municipal public works
facilities is to provide essential services and render
urban living and life processes convenient, safe, and
comfortable. Cost often is a forgotten factor — and is
frequently of secondary importance when any
failures or disruptions of services are experienced.
The need to restore the operability of urban
functions when they have been disrupted is
paramount in the minds of the public and their public
officials.
The effects of infiltration and inflow on the
successful functioning of public sewer systems,
pumping stations, and sewage treatment plants, and
combined sewer overflow structures, frequently are
viewed from the standpoint of physical conditions
rather than of basic economic criteria. For example:
When excessive sewer flows result in local
street area flooding and inundation of private
properties, the main task is to alleviate the
surcharge effects, drain the flooded area and
properties, and restore the area to clean
condition. The question of cost is secondary.
When sewage pumping stations and sewage
treatment plants are by-passed, or operated
at excessive loadings and reduced
efficiencies, the major concern is the
pollutional effects of the spilled untreated
flows or the discharge of effluents of lowered
quality. The fiscal factors are not considered.
When combined sewer overflows are more
frequent or last longer than usual, because of
the intrusion of infiltration or inflow,
today's concern centers on the degradation
of the receiving waters, rather than on the
cost of such pollution.
But these impacts of infiltration and inflow
on collection, treatment, and disposal
systems and receiving waters have economic
implications even though the economic
factors may be veiled. They must be weighed
if jurisdiction officials are to evaluate the
cost of overcoming the "Two I's" and
compare the costs of permitting these
conditions to continue with the benefits to
be derived from corrective actions.
From investigations of representative
jurisdictions and national statistical surveys,
efforts were made to determine if some type
of "price ticket" could be attached to the
cost of infiltration and inflow, and the cost
of control ascertained.
Economic Effects On Sewer Systems
The effects of infiltration and inflow on sewer
systems have been outlined in Sections 2,4, and 5 of
this report. The findings of the various national
investigations and surveys of practices and
experiences in representative and statistical
jurisdictions have been evaluated; they have been
coupled with information obtained through inquiries
to consulting engineers and state and provincial water
pollution control agencies.
The research data are mainly related to physical
rather than economic factors. The question must be
asked: What are the economic impacts of infiltration
and inflow on the vast network of sewers serving the
United States and Canada?
The mileage of sewer systems constructed and in
service in urban areas of the nation are staggering in
their length and almost irreplaceable in their dollar
value. Without dependable sewer service, the entire
structure of urban residential, commercial, and
industrial progress would fail.
According to a survey reported by the Water
Industries and Engineering Services Division of the
Business Defense Service Administration, U.S.
Department of Commerce, 1,978.3 million feet of
"residential sewer pipe" were in service in the United
States by 1965, serving 140 million persons. The total
sewer footage was to reach an estimated 2,942.4
million feet by 1970. It was predicted that an
additional 1,240.4 million linear feet of sewers would
be constructed in the decade between 1970 and
1980, to meet the needs of the growing urban
complexes of America. By 1980, it was estimated,
3,732.8 million feet of residential sewer pipe would
be in service, to handle the flow from 178 million
urban residents.
Between 1964 and 1980, it was projected in
another part of the Federal statistics, urban growth
would require 2,198.8 million feet of 8-inch to
12-inch pipe; 214 million feet of 15- to 24-inch pipe,
and 107.1 million feet of over 24-inch pipe, or a total
of 2,520.5 million feet in coterminous United States.
In addition, an estimated 649.1 million feet of sewer
pipe will be required by 1980 to replace inadequate
sewers now in service.
89
-------
If excessive infiltration and avoidable inflow
presently are usurping some 15 percent of this sewer
capacity — an estimate that appears conservative on
the basis of national data obtained during this
project — it is evident that the equivalent of 440
million feet of sewers is now rendering this type of
"pirated" service and handling flows of waste water
that are "extraneous" under the terms of this study.
In addition, on the basis of the 15 percent
infiltration/inflow estimate, about 185 million linear
feet of sewers might be saved in the future
construction programs of municipalities if excessive
infiltration and inflow could be eliminated.
It is conjectural whether or not the elimination
of infiltration and inflow in the existing 2,942 million
feet of sewers by rehabilitation methods could
obviate some 15 percent of the vast construction
burden of the 1970-1980 decade. However, some
form of "price ticket" is applicable to this situation.
Assuming the average cost of urban sewers of all sizes
to be $15 per foot, the construction program for
sewer installation between 1970 and 1980 will
require the expenditure of $19 billion. Actually, the
Business and Defense Services Administration's
estimated cost for sewer construction for the period
from 1964 to 1980 is $39 billion. If even 5
percent — or one-third of the assumed 15 percent
infiltration impact - could be saved by improved
control of infiltration and inflow, there could be a
reduction of $1 to $2 billion in new sewer
construction. The economic implication of
infiltration and inflow control is obvious, even if the
dollar data are only assumed.
A study of the needs of urban hydrology in the
United States carried out by the American Society of
Civil Engineers in 1969 under the sponsorship of the
U. S. Geological Survey, Department of the Interior,
reported the dollar value of sewer utilities now in
service and the annual construction needs for sewage
systems for the next several years. The data revealed
that the replacement value of public sanitary sewers
and treatment facilities is approximately $40 billion.
Annual construction needs for sanitary sewers were
estimated at approximately $1.5 billion, and storm
sewers at about $2.5 billion.
The fiscal or economic motivation for correcting
infiltration and inflow conditions is self-evident. The
dollar value of extending the useful life of existing
sewers and initiating better construction methods for
the sewers of the future is augmented by the
pollutional control benefits to be derived. The latter
would represent an additional "profit" from the job
of providing better sewers for anticipated national
growth.
Economic Effects of Extraneous Water: Case
Histories
Entry of extraneous waters into a separate sewer
system, or construction of a separate sewer system
with excessive allowances for infiltration and storm
flow, can have a substantial effect on the economics
of the system. Capital costs are increased by the need
to provide excessive capacities in such a system.
Maintenance and operation costs are increased by the
need to collect, transport, pump, treat, and dispose of
the excessive flows thus encountered.
When excessive infiltration and storm inflow
occur in a system or are permitted by adopted
engineering design criteria, the cost of construction of
all portions of the systems is increased. In a study
conducted for the Central Contra Costa Sanitary
District in California, it was determined that an
increase in infiltration and storm inflow allowances
from 600 to 2,000 gallons per acre per day would
increase by 33 percent the size of sewers required to
serve a typical residential area. This amounted to 100
inch-feet of sewer per acre. The term "inch-foot" is
the product of the sewer diameter in inches and its
length in feet. At a cost of $1 per inch-foot, this
would represent an increase of $100 for sewering one
acre at the increased infiltration rate.
Costs would increase similarly for constructing
trunk and interceptor sewers with capacities adequate
for the excessive infiltration cited in the Contra Costa
example. A trunk serving an area of 10,000 acres
would cost approximately $100,000 per mile more if
constructed with a capacity to handle the higher
rather than the lower rate of infiltration — 2,000
gallons per acre per day rather than 600 gallons.
Presenting another example of the economic
effect of excessive infiltration and storm inflow, a
report prepared for a municipality in the Pacific
Northwest stated:
"Because of the major effect that ground water
infiltration and storm water inflow exert on the cost
of the recommended long-range sewer system plans, it
is worthwhile to discuss this effect as well as the
available remedies. It was pointed out that peak
wet-weather flows are on the order of seven to eight
times the normal dry-weather flow of sewage alone.
Since the existing system was not designed to convey
or treat flows of this magnitude, the only available
solution has been to by-pass flows untreated directly
into the river. These by-passes have been in violation
of the pollution control policy established by the
sanitary authority.
'The problem can be corrected by (a) eliminating
or reducing infiltration and inflow at the source; (b)
collecting, conveying and treating the total waste
90
-------
stream including storm and ground water; or (c) a
combination of the two methods. Since the major
source of the trouble appears to stem from poorly
constructed sewers laid below the ground water table,
it is not likely that the source of the excess flow can
be easily located or economically corrected. The
alternative will require construction of a relief sewer
along the north bank of the river to intercept and
convey to the treatment plant those flows which are
presently being by-passed untreated directly to the
river. Further study will be necessary to determine
the best solution to the excess flow problem.
"Insofar as the sewage treatment plant is
concerned, this report assumes that the present
condition of excess infiltration and inflow will remain
uncorrected in the existing sewers, but will be largely
prevented in new sewer construction. This means,
very simply, that Stage 1 of the treatment plant
expansion will be nearly twice as large as would
otherwise be necessary, and that operating costs will
be higher than would be necessary if excess flow
could be eliminated.
"In view of the requirements of the sanitary
authority that the sewer system must be brought into
compliance with discharge requirements by 1970, it is
unlikely any significant reduction in infiltration and
inflow can be made in time to permit a reduction in
the design capacity of the Stage 1 treatment plant.
Any future flow reduction, however, will result in a
deferment of the date when Stage 2 expansion must
be undertaken. Since Stage 2 expansion of the plant
represents an expenditure of $1.7 million in 1969
dollars, there is an obvious financial advantage to the
city in correcting present infiltration problems."
Other economic situations are reported.
Literature on them has been augmented by
information obtained in the present national study of
the inflow and infiltration problem. The investigator's
report on interviews with city officials in Yakima,
Washington, for example, contained this statement:
"The detrimental effect of excessive infiltration
in this city can best be illustrated by the fact that an
addition to the sewage plant, completed in 1965 at a
cost of $1,230,000 would not have been necessary if
infiltration had not been involved. Last year, 3,749
million gallons of sewage were treated at a cost of
operation and maintenance, alone, of $99,051.30.
Using a rate of 110 gallons per day per capita and a
combined population of 55,000 - 48,000 in the city
and 7,000 in the suburbs — the expected sewage flow
would have been 2,190 million gallons, with a
treatment cost of $57,837.90. Thus, it can be
conservatively said that extraneous water in the sewer
system is costing this city more than $41,000 per
year."
In the case of Bloomington, Minnesota, which
pays another authority for sewage treatment services,
the public works director has estimated that each
gallon per minute of extraneous water costs the city
$100 per year.
A report prepared for Marin County, California,
contains the following statement: "It is estimated
that if storm water inflow in the Corte Madera and
San Rafael watersheds could be reduced to a level
similar to that found in well-constructed community
systems, the cost of the recommended plan could be
reduced $3 million below the $19 million estimated."
In a large metropolitan area in Australia, it has
been estimated that it will cost in excess of $50
million to correct deficiencies in a major interceptor
system. The deficiencies are described in a report on
the system as follows:
"Insufficient sewer capacity for peak
wet-weather flows is the primary deficiency in
sewered areas and, at a local level, leads to a variety
of undesirable effects such as backing up of sewage
into house services and overflowing manholes. On a
larger scale, the lack of capacity leads to overflows of
sewage to watercourses in the harbor... flows in
excess of calculated peak capacities often occur as a
result of entrance of excessive amounts of storm
water principally through illicit drainage connections
or faulty pipe joints."
The $50 million cost cited above is only for
correction of the interceptor sewer itself. Additional
expenditures are necessary to correct the deficiencies
associated with the trunk and collection system.
Winnipeg, Canada, reported it is constructing
sewers at a cost of $ 15 million to provide relief of
combined sewers from surcharged conditions
occurring during wet-weather periods.
That the entrance of extraneous waters into
sanitary sewer systems raises costs of maintenance
and operation of treatment and pumping facilities is
evidenced by data obtained through interviews in the
national investigations, as described earlier in this
report. Table 42, Cost of Treatment and Pumping of
Infiltration and Inflow, is a summary of these
interview-derived cost data from representative
jurisdictions. Although 12 of the 21 agencies did not
report any costs, primarily because of lack of
information on infiltration and inflow volumes, the
ones that did report them showed that substantial
sums are expended for treating and pumping the
extraneous water.
Sewer stoppages and cave-ins have been cited by
91
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TABLE 42
NATIONAL FIELD INVESTIGATIONS
COST OF TREATMENT AND PUMPING
OF INFILTRATION AND INFLOW
Estimated Annual Cost'3' of
Treatment and Pumping
Jurisdiction Infiltration Inflow Total
Watsonville,
California $19.009 $ 8.928 $27.937
Nassau County,
New York 5,600 40,000 45,600
New Orleans,
Louisiana b b b
Bloomington,
Minnesota c c c
Yakima,
Washington NR NR NR
Province of Ontario,
Canada d d d
Jacksonville,
Florida e e e
Winnipeg,
Canada NR NR 208 f
Baltimore,
Maryland g 99
a - Dollars per year unless otherwise noted
b - Pumping costs significantly increased; all flow
pumped; 50% increase in cost during heavy rain
c - $100 per year for each 1 gpm of extraneous water
d - Earlier plant expansion, average cost of treating
sewage times additional flows experienced during
wet-weather
e - Treatment $130 per million gallons normally, $11
per million gallons pumping; increased flow causes
increased expenses
f - Pumping only
g - Cost of of treatment Back River Plant - $37.59
per million gallons. At infiltration-inflow rate of
100 mgd, cost is $3,700 per day. No records of
total hours of excess flows during any year.
NR - No report
most of the interviewees as one of the major
economic effects.of excessive waters entering sewer
systems. In Omaha, Nebraska, three full-time crews
are maintained to clear stoppages and perform other
emergency work. Clearing the stoppages costs an
estimated $16 to $17 per joint.
San Jose, California, reported that corrective
work on its sewer system cost $200,000 over a
10-year period, and that 40 percent of the
maintenance cost was expended for emergencies,
primarily on sewers. Numerous cave-ins, with an
attendant average cost of cave-in repair of $300, were
reported in Jacksonville, Florida. At the time of the
investigation interview, there were 180 known
cave-ins awaiting or undergoing repair. That city is
embarking on a program to replace approximately
130 miles of defective sewers at a cost of $15 million.
Milwaukee, Wisconsin, reported that about $2 million
per year is spent replacing old sewers and
constructing relief sewers.
Of all the jurisdictions interviewed, corrective
actions generally have been taken on a case-by-case
basis. At New Orleans, Louisiana, corrective action on
a problem basis is not economically feasible and a
systems approach is necessary. This city stated that
correcting the infiltration problem is invaluable and
necessary, and that it is becoming increasingly
important with implementation of the city's sewage
treatment program. The Sewerage and Water Board
has conducted a pilot correction program. The
average unit cost to repair the sewer lateral was $2.25
per foot. In addition, it was found that all building
sewers twenty years of age or older should be
replaced at an estimasted cost of at least $2.82 per
connection.
During the investigations of the 26 representative
jurisdictions, very little information was obtained on
the cost-benefit ratio of corrective actions to alleviate
the problem of extraneous water in sewer systems. In
one project undertaken in Bloomington, Minnesota, it
is reported that corrective action costing $3,500
eliminated about 60 gpm of infiltration. The
estimated annual savings resulting from this action
were reported as $100 per gpm, or $6,000. The
utility director of Ft. Lauderdale, Florida, said the
corrective action program in effect there since 1957
has prevented overload conditions at the treatment
plants.
In any sewer system, benefits to be achieved by
eliminating or reducing infiltration and inflow into
existing sewers must be evaluated against costs. The
direct economic benefits to be obtained are readily
ascertainable. To these must be added the less
tangible benefits of public safety and convenience,
which might be classified as hidden benefits further
offsetting many of the hidden costs of infiltration
and inflow.
Benefits Derived From Corrective Actions
What has already been stated in this section
92
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TABLE 43
NATIONAL STATISTICAL SURVEY
HAVE BENEFICIAL RESULTS BEEN OBTAINED
FROM CORRECTIVE ACTIONS?
Population 200.000+ 100,000-199,999 20,000-99,999 10,000-19,999 Under 10,000
Totals
Regions Yes No NA Yes No NA Yes No NA Yes No NA Yes No NA Yes No NA
East
South
Midwest
Southwest
West
Canada
5
7
2
4
6
2
-
-
—
-
0
1
4
1
2
3
1
1
4
4
6
1
5
—
2
2
—
—
1
—
1
—
—
1
2
2
8
4
10
7
12
4
3
1
1
1
2
—
12
5
5
2
16
6
1 1
1
3 -
2 -
5 -
1
3
3
4
2
6
2
_
—
1
—
1
1
- 1
_ _
- 1
- 2
0 2
- 1
18
16
22
14
29
8
6
3
1
1
3
1
21
9
12
10
27
12
Totals
26 1 12 20
45 8 46 13
demonstrates that the elimination of infiltration is
desirable, and often necessary, to preserve the
usefulness and service life of sewer systems, sewage
pumping stations, and treatment plants. In addition,
operation and maintenance of these facilities will
benefit greatly from the elimination of ground waters
that are "extraneous" to the basic function of these
structures and therefore to be considered as
intrusions pirating essential system capacities.
Accordingly, this project tried to ascertain the
benefits derived from corrective actions taken by
jurisdictions covered in the national investigation of
the 26 representative jurisdictions plus the large
number of systems covered by the national statistical
survey. Such an economic weighing of costs versus
benefits cannot be expected to provide specific "price
tickets" on reduction in pollutional discharges that
occur during (1) by-passing of raw or inadequately
treated sewage at sewage pumping stations and
treatment plants, (2) emergency spills at points in
sanitary sewer systems, or (3) excessive overflows of
storm waters from combined sewer regulator stations.
Table 43, National Statistical Survey, Have Beneficial
Results Been Obtained from Corrective Action?,
presents data on the beneficial results of actions
already undertaken by jurisdictions.
For the statistical jurisdictions responding in the
United States and Canada, the vastly predominant
opinion was that benefits have derived from
infiltration correction projects. There were no
marked variations of opinion among the different
population groups. While in general a consensus
existed for all sections, the Midwest and West
20
7 107 15 91
provided the greatest number of affirmative opinions
and the smallest percentages of negative ones.
For the entire survey, responses to this question
showed 101 jurisdictions where benefits were
achieved and only 10 where they were not.
It is important to note that these opinions on
benefits derived from infiltration projects were not
based on actual economic evaluations of costs versus
benefits. An inquiry showed that 125 jurisdictions or
more than 90 percent of those reporting, had made
no economic analyses of infiltration correction; only
about 8 percent had statistically evaluated the
economic results. In the Midwest and Southwest,
none of the replies indicated economic evaluations.
Data on costs and corrective measures were not
accompanied by explanation of the methods used in
this improvement work, except in one case where a
dig-up job was listed as costing $200 and a sealing job
as costing $3 per linear foot. Costs per linear foot
were reported to range, in general, from $5 to $35
per linear foot. One project reportedly cost $70 per
linear foot. Another jurisdiction cited a cost of only
$0.15 per foot without any explanation of the
method utilized. Another respondent said the cost of
infiltration control was the same as for new
construction. This may be interpreted as referring to
a physical replacement of defective sewer lines.
Because of the undue range in reported costs of
correcting infiltration, any firm computation of
average national experience is precluded; but a
general cost in the area of $5 to $20 per foot might
be estimated.
One reply said a manhole job cost $2,000.
93
-------
Another reply gave the cost of sealing 44 leaks as
$5,909. Still another jurisdiction reported an
expenditure of $50,000 for infiltration correction,
apparently by means of sewer replacement and repair,
at a unit cost of $20 per linear foot.
In a majority of cases, resoonding jurisdictions
reported no cost data. The number not replying
cannot be disregarded. It leads to the conclusion that
more public officials should give further attention to
this important operation and maintenance phase of
sewer system management and administration.
It is obvious, from the broad spread of cost
figures provided, that methods used for infiltration
correction may have varied widely. At any rate, it
would be inadvisable to use survey information as a
basis for any firm conclusions on cost of infiltration
correction. However, the dearth of information and
the lack of any uniformity in cost figures cannot alter
the estimate of $15 per linear foot of sewer
construction. This estimate, used earlier in this
section to ascertain the economic effect of
infiltration on future sewer construction programs,
seems justified in the light of even the scattered cost
data disclosed by the survey.
The preponderance of opinions that infiltration
control is beneficial economically must be classed as a
specific finding of the survey, even though this
consensus was not supported by meaningful
economic analyses of the nature sought by the
national statistical survey. Requirements for tertiary
treatment of wastewater treatment plant effluents at
a cost up to $0.30 per 1,000 gallons will tend to
make infiltration and inflow control an economic
necessity.
Plans for Future Corrective Actions
As stated earlier in this report, the national
statistical survey attempted to ascertain whether or
not jurisdictions in the United States and Canada
intend to carry out pre-corrective surveys of
infiltration conditions in their sewer systems; whether
such surveys will be followed by actual corrective
actions, where needed or indicated, and whether
budgetary funds have been, or will be, allocated for
such work.
The survey endeavored to ascertain if the plans
for corrective action were nebulous, actually backed
up by budgetary appropriations for current
expenditures, or for a five-year program. Survey
responses were highly variable, and not definitive
enough to warrant specific interpretation. However, it
is apparent that in a number of jurisdictions actual
funding for infiltration correction is a reality.
In the over-200,000 population class, one
corrective program was reported to involve the
expenditure of $500,000 per year. Another
jurisdiction reported budgeting for $200,000 to
$750,000 worth of construction work to overcome
excessive infiltration. Still another jurisdiction
indicated that it planned to spend from $ 150,000 to
$500,000. In another case, planned work will cost
from $300,000 to $1,000,000. The large extent of
such work in the over-200,000 population category
indicates infiltration control now is a valid and
recognized facet of sewer maintenance programs in
the larger municipalities of the United States and
Canada.
In the jurisdictions with populations of 100,000
to 200,000, more limited budgeting was reported,
ranging from $10,000 to $250,000. In the
under-10,000 group, low-budgeted cost figures were
reported. In the 10,000- to 20,000-class, minor
expenditures of $5,000, $23,500, $10,000, $40,000,
and $50,000 were cited as contemplated for current
or five-year programs. In the 10,000-20,000
population class in Canada, the highest expenditure
reported from respondent jurisdictions was $50,000.
The data obtained by the statistical survey
admittedly are sparse. However, one finding does
stand out as a result of the national statistical survey:
Many jurisdictions are planning surveys and corrective
actions, and validating these intentions by the
specificity of their plans to allocate and expend
budgeted sums of money for this purpose.
Admittedly, this is not a universal trend, but it is
widespread enough to stimulate other communities to
embark on positive planning and allocations of funds
for infiltration surveys and infiltration corrective
actions.
94
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SECTION 9
ACKNOWLEDGEMENTS
The American Public Works Association is deeply indebted to the following persons and their
organizations for the services they rendered to the APWA Research Foundation in carrying out this
study for the local governmental jurisdictions and the Environmental Protection Agency who
co-sponsored the study. Without their cooperation and assistance the study would not have been
possible. The cooperation of the American Society of Civil Engineering (ASCE) and the Water Pollution
Control Federation (WPCF) is acknowledged for their participation on the project Steering Committee.
STEERING COMMITTEE
Paul C. Soltow, Jr. (Chairman), San Pablo Sanitary District
George E. Burns, Metropolitan Corporation of Greater Winnipeg
Richard L. Castle, Oakland County, Michigan, Department of Public Works
S. J. McLaughlin, The Metropolitan St. Louis 'Sewer District
Alfred R. Pagan, (ASCE), Bergen County, New Jersey, Engineer's Office
Lloyd Weller, (WPCF), Black & Veatch Consulting Engineers
PANEL OF CONSULTANTS
Frank Kersnar, Brown & Caldwell, Consulting Engineers
Walter Thorpe, Toltz, King, Duval, Anderson & Associates, Consulting Engineers
Charles R. Velzy, Charles R. Velzy & Associates, Consulting Engineers
CONSULTANTS
Dr. Morris M. Cohn, Consulting Engineer
Richard Fenton, Consulting Engineer
Harry Grounds, Toltz, King, Duval, Anderson & Associates, Consulting Engineers
H. Storch, Storch Engineers
FIELD INTERVIEWERS
William L. Bryant, Flood & Associates, Jacksonville, Florida
Robert E. DeLoach, Flood & Associates, Jacksonville, Florida
Robert S. Gemmell, Professor, Northwestern University
John Morin, Former City Engineer, Oakland, California
Dean Sellers, Chief Engineer, Construction, Wichita, Kansas
Steve M. Slaby, Professor, Princeton University
ENVIRONMENTAL PROTECTION AGENCY
Darwin R. Wright, Project Officer
William A. Rosenkranz, Chief, Storm and Combined
Sewer Pollution Control Branch, Division of Applied
Science and Technology
95
-------
INDUSTRIAL ADVISORY PANEL
Leland E. Gottstein (Chairman), American Pipe Services
Charles M. Aiken, Raymond International, Inc.
James R. Alley, Certain-teed Products Corp.
Joseph P. Ashooh, Associated General Contractors
Donald M. Cline, Pacific Clay Products
Robert H. Hedges, Rockwell Manufacturing Co.
Quinn L. Hutchinson, Clow Corporation
Harold Kosova, Video Pipe Grouting, Inc.
Tom Lenahan, Halliburton Services
W. J. Malcolm, Cherne Industrial, Inc.
Joseph McKenna, Industrial Material Company
Charles Prange, Rockwell Manufacturing Company
John Roberts, Armco Steel Corporation
Joseph A. Seta, Joseph A. Seta, Incorporated
Harry W. Skinner, Press Seal Gasket Corporation
E. W. Spinzig, Jr., Johns-Manville Sales Corporation
Edward B. Stringham, Penetryn System, Incorporated
William M. Turner, Griffin Pipe Products Company
Joe A. Willett, American Concrete Pipe Association
John A. Zaffle, United States Concrete Pipe Company
ADVISORY COMMITTEE
Paul C. Soltow, Jr
E. Nay Bentley, Indianapolis, Indiana
C. A. Boeke, Middletown, Ohio
Philip A. Boiler, Muncie, Indiana
G. Briere, Montreal, Quebec, Canada
G. E. Burns, Winnipeg, Manitoba, Canada
Richard L. Castle, Pontiac, Michigan
Milton R. Christensen, Minneapolis, Minnesota
William R. Davis, Pittsburgh, Pennsylvania
Robert Grant Dietrich, Baltimore, Maryland
David W. Duncan, Charlotte, North Carolina
John E. Eastus, San Jose, California
W. T. Eefting, Miami, Florida
Walter A. Fielding, Akron, Ohio
W. D. Oilman, Richmond, Virginia
Stephen H. Goodman, Campbell, California
Forrest Grant, Jr., Columbus, Ohio
Allison C. Hayes, Boston, Massachusetts
, San Pablo, California (Chairman)
Paul T. Hickman, Springfield, Missouri
R. J. Horgan, Toronto, Ontario, Canada
Joseph Irons, Chicago, Illinois
Roy L. Jackson, Kansas City, Missouri
W. I. Jefferies, Arlington, Virginia
Roy W. Likins, Daytona Beach, Florida
Robert P. Lowe, Albuquerque, New Mexico
Frederick A. Mammel, Ann Arbor, Michigan
0. H. Manuel, Charlottetown, Prince Edward Island, Canada
Herbert D. McCullough, Milwaukee, Wisconsin
Marvin J. Miller, San Carlos, California
E. W. Ott, Seattle, Washington
John W. Schneider, Oshkosh, Wisconsin
Philip W. Slagel, Topeka, Kansas
R. Marlin Sumner, St. Clair Shores, Michigan
George H. Wilton, Wichita, Kansas
John Winden, Puyallup, Washington
96
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SECTION 10
GLOSSARY OF PERTINENT TERMS
Area way—A covered or uncovered platform on
paved entrance to a grade or below grade entrance of
a building, usually equipped with a drain to remove
precipitation runoff water.
Building Sewer-The conduit which connects
building waste water sources to the public or street
sewer, including lines serving homes, public buildings,
commercial establishments, and industrial structures.
In this report, 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; (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.)
By-pass—A pipe line which diverts waste water
flows away from or around, pumping or treatment
facilities — or by-passes them—in order to limit the
flows 'delivered to such facilities and prevent
surcharging or adversely affecting their operation or
performance.
Cellar Drain—A pipe or series of pipes which
collects waste waters that leak, seep, or flow into
subgrade parts of structures and discharges them into
a building sewer or disposes of them by other means
in sanitary, combined or storm sewers. (Referred to,
also, as "basement drain.")
"Clean Waters"—Vfuste waters from commercial
or industrial operations that are uncontaminated; do
not need, and could not benefit from, waste water
treatment processes, and 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 to
larger interceptor sewers and pumping and treatment
works. (Referred to, also, as "Street Sewer.")
Combined Sewer-A pipe or conduit which
collects and carries sanitary sewage with its
component commercial and industrial wastes and
infiltration and inflow waters at all times, and which,
in addition, serves as the collector and conveyor of
storm water runoff flows from street and other
sources during precipitation and thaw periods, thus
handling in a "combined" way all these types of
waste waters.
Exfiltration—The leakage or discharge of sewer
flows into the ground through pipes, joints,
manholes, or other sewer system structures; the
reverse of "infiltration."
Foundation Drain—A pipe or series of pipes
which collects ground water from the foundation or
footing of structures and discharges these waters into
sanitary, combined, or storm sewers, or to other
points of disposal, for the purpose of draining
unwanted waters away from such structures.
Ground Water Table—The top elevation of the
ground water contained in the soil, as it varies from
season to season or from time to time because of
precipitation and drainage conditions. Immersion of
sewer pipe in ground water, partially or completely
under the ground water table, causes infiltration,
through the natural phenomenon of water seeking its
lowest level.
Infiltration—The discharge of ground water into
sewers, through defects in pipe lines, joints, manholes
or other sewer structures.
Inflow—The discharge of any kind of water 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 "infiltration" and is distinguished from
such waste water discharges, as previously defined.
Infiltration/Inflow—A combination of infiltration
and inflow waste water volumes in sewer lines that
permits no distinction between the two basic sources
and has the same effect of usurping the capacities of
sewer systems and other sewer system facilities.
Infiltration Allowances—The amount of
infiltration that is anticipated in sewer systems,
considered inevitable under sewer construction and
sewer service conditions, and authorized and provided
for in sewer system capacity design and in sewer
construction practice. A distinction is made between
"sewer design infiltration allowances" which the
designer provides for in-structuring the total sewer
system, and "construction infiltration allowances"
permitted in the specifications covering the
construction of specific projects and specific sections
of the total sewer system.
Interceptor Sewer A sewer which receives the
flow from collector sewers and conveys the
wastewaters to treatment facilities.
97
-------
Joints-The means of connecting sectional
lengths of sewer pipe into a continuous sewer line,
using various types of jointing materials with various
types of pipe formations which make possible the
jointing of the sections of pipe. The number of joints
depends on the lengths of the pipe sections used in
the specific sewer construction work.
Jurisdiction—Any governmental entity, such as
city, town, village, county, sewer district, sanitary
district or authority, or other multi-community
agency, which is responsible for and operates sewer
systems, pumping facilities, regulator-overflow
structures, and waste water treatment works.
Overflow—A. pipe line or conduit device, together
with an outlet pipe, that provides for the discharge of
portions of combined sewer flows into receiving
waters or other points of disposal, after a regulator
device has allowed the portion of the flow which can
be handled by interceptor sewer lines and pumping
and treatment facilities to be carried by and to such
water pollution control structures.
Pipe Seeding—A. method of correcting leaks or
defects that cause infiltration of excessive extraneous
waters into sewers using physical or chemical
materials, applied by interior or exterior means, and
sealing such points or defects so that the infiltration
waters are reduced or eliminated.
Pipe Tests—Various methods for testing sewer
lines (after construction and in service) to ascertain
whether or not infiltration allowances have been met,
and locating the sources of infiltration that exceed
construction specifications. Such tests include
infiltration tests, exfiltration tests, air tests, and such
means as smoke bomb tests to locate sources of
infiltration in new and existing sewer lines.
Precipitation—Rainfall or thawing snow and ice
that produce storm water runoff from streets, roads,
and other impervious surfaces; percolate into the soil
and augment the ground water; are held in the
interstices of the soil; produce inflow into sewer
systems, or affect the ground water table.
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
storm water downward from the roof of a structure
and then into a sewer for removal from the property,
or onto or into the ground for runoff or seepage
disposal.
Roots—Fine or capillary root formations from
trees that enter sewer lines, primarily sanitary sewers,
in search for water and cause clogging of these
conduits as the roots grow in length and volume. In
the context of this report, the significance of root
formations in sewers is that they enter into sewer
lines through the same pipe and joint defects as those
which permit infiltration or exfiltration to occur.
Sewer Inspection—Methods for determining the
condition of new or existing sewer systems (in terms
of infiltration conditions) by visual inspection,
closed-circuit television viewing, photographic
methods, or other means.
Sewer-Use Ordinance—A regulation, code, or
ordinance enacted by a jurisdiction to specify the
types and volumes of waste waters that can be
discharged into sewer systems, the waste waters that
cannot be so discharged, and the fees or charges to be
imposed for the privilege of discharging those wastes
and volumes which are permitted.
State and Provincial Water Pollution Control
Agency—A branch of the government which imposes
and enforces water quality standards, establishes
standards of design for sewer systems and pumping
and treatment facilities, and has responsibility for
maintaining established water pollution control
standards in receiving waters.
The "Two J's"-A phrase adopted for this report,
to designate the two factors of infiltration and inflow
which affect sewer systems and the other waste water
handling facilities evaluated in this project and report.
98
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SECTION 11
BIBLIOGRAPHY
As a part of the Project, a bibliography was developed. Entries
have been limited to references which give information pertinent
to control of infiltration and inflow. Articles without technical
information are not included. Author and subject indices are
provided. Bibliography items are not listed in any order, but are
identified by a serial number.
Author Index 104
Subject Index 106
Bibliography 110
99
-------
BIBLIOGRAPHY
AUTHOR INDEX
"Av
Number
Aguero,C.P 101
Aluminum Pipeline Case History Study . . . 045
American City, The '046,075,082,098
American Society of Civil Engineers
& Water Pollution Control Federation 024
Andrews, R. G 049
American Concrete Pipe Assn 002,097
American Public Works Association 002,097
Austrab'an Plastics & Rubber Journal 174
'B"
Baker, D. A 154
Barlund, S 019
Batterman, R. H 083
Baugh,E.J 073
Bell,G.S 060
Birch, S. B., Jr 001
Bolton.W.H 109
Bremner, R.M 120
Brick & Clay Record 152
British Plastics 035
Brokaw.A.T 114
Brown and Caldwell 003
Brown, K.W 053
Brubacher, R 074
Brunton, B.W 105
Building Officials and Code
Administrators Int'l. Inc 133
Building Research Advertising Board 022
Burmeister, R. A 055
"C"
Cast Iron Pipe Association 118
Chase, W. J 131
Civil Engineering 124
CIapham,T. W 087
Clark, G.W 041
Clarke, N. W. B 037
Clay Sewer Pipe Association 017
Cohn, M. M 104
"D"
Dahlmeyer, F. D 072
Dalton,W. C 095
Dick, J. M 076
Downing, Paul B 130
Duff,H.W 131
Number
Falardeau, R. E 044,088,090
Finn, J. R 086
Fladring, J. F 125
Foster, Jack O 122
Franquin, J 153
Fulton, G. P 085
"G"
Gaskin.J Ill
Geyer, J. C 038
Gifft.H.M 047
Girling, R.M 127
Graeser.H.J 119
Greeley, S. A 059
'H"
Haney.B.J 031
Hansh, Harold H 166
Hay.T.T 008
Hayes, R. H 088
Henderson, F. M 108
Hills, D. A 107
Hobbs, S. H 048
Holland, J. E 050
Hood.J.W 116
Hurlbert,D 100
Hutchinson, G. D 023
T'
International Association of
Plumbing and Mech. Officials
"J"
135
Johnson, C. A 013
Johnson, C. F 058
Johnson, Lyle D 132
"K"
Kaufman, J. E 069
Keefer.C. E 021
Kern, J. A 113
King, R.C 051
Kirkham.D 004
Kunnen.T 014
100
-------
"L" Number
Langbein, W. B., et al 009
Larmon, A 061
Lawrance, C. H 007
Leavy, R. D 057
Leute, J. J 028
Lincoln, R. A 020
Llewellyn, T. E 099
MacDonald, T. W 042
Malcolm, W.J 121
Marshall, R 093
Metz, J 098
Miller, F. J 062
Moffitt, R. B 063
Murray, T. R 026
Myers, U.I 167
Nadung, J. F 045
Neal.M 032
Nester, N. W 068
Nettles, E. H 081,053
Nooe, R 112
Nussbaumer, N. L 018
«p«
Peckworth, H. F 027
Pelishek,R 034
Porter, J. B 012
Public Works 033,039
"R"
Ramseuer, G. C.Rick 029
Randall, F. G 056
Rayner, G. Z 084
Reed,M. D 161
Roberts, J. S 054
Number
Rowan, P. P 129
Rutz.G 115
"S"
Santry,I.W.,Jr ................. 126,140
Schacher, T.P .................... 043
Seal, K. E ....................... 040
Sirrett,J ........................ 006
Smith, D. R ...................... 030
Southern Building Code Congress ......... 134
Southern Clay Pipe Institute ........... 025
Stallings, J. R., Jr .................. 071
Starns, R. M.,Jr ................... 064
Stepp, S. G ...................... 094
Sullivan, R. H ..................... 065
Surveyor, The ................... 110
Thomas, R. E .................... 036
Thornquist, H. T ................... 090
"U
U. S. (Engineers Dept.) 015
U. S. (FWPCA) 005
U.S.(PHS) 128
"V"
Velzy, C. R.
. 016
Ward, Josephs 117
Water & Sewage Works 033,059
Water Pollution Control Federation . . 036,114,115
Watkins,L.H 010,027
Watson, J.W 070
White, R 096
Wilhoff.T.L 123
Wood, J.W 066
101
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BIBLIOGRAPHY
SUBJECT INDEX
"A" Number
Air Testing 002,029,043,048,052,121,131
Asbestos-Cement Pipe 040,050,154
Asphalt Compound 092
"B"
Backwater Protection 095
Bedding 017,042
By-passes 005
Cast Iron Pipe 119-
Caulking 064
Clay Pipe 006,025,029,040,152
Clay Soils 050
Combined Sewers 005,009,018,058,059,065,109
Concrete Pipe 027,033,035,037,039,040,045,046,113,116
Construction 002,024,034,044,104,117,119
Construction Procedures 017
Control Practice 016
Control Treatment Methods 005
Copper - Ceramic Tile 063
Copper Sulphate 063,066,067,093
Corrosion 052,153
Design 002,012,017,022,024,025,027,028,031
033,038,040,047,051,104,108,112,116
Drainage 112
Economics 003,007,030,102,103,104,115,128,129,130
Excess Flow 008
Exfiltration 019,045,125
«F»
Foundation 042
Flow Measurements 001,012,023,028,030,054,127
"G"
Ground Water 030,041,108,
Grouting 070,082,083,096,098,100,101,105,116
102
-------
"H" Number
House Connections 003,060
"I"
Illicit Connections 079
Industrial Waste 012
Infiltration 005,008,012,020,030,031,033,036,052,053,056,111,126
Infiltration Tests 016,019
Inspection 085,086,087,089,127
Installation 025,027
Interceptor 046
Investigations 099
"J"
Jet Cleaner 102,013,014,015,016,021,026,029,032,034,
035,039,040,041,046,053,055,064,070,072,
092,094,096,099,100,101,102,107,109,119,155
CCT 9
L"
Laughing Gas 069
Leak Detection 070,071
Leakage 064
Liners 103,120,122,160
"M"
Maintenance 068,073,076,081,086,097,101,114
Materials Protection 045
"XT"
Nitrous Oxide ................................................. 069
"0"
Overflows ........................................... 005,058,059
Percolation ................................................. 010,011
Permeability ................................................. 053
Photography .................................. 003,044,070,079,085,089,091
Planning ................................................ 104
Plastic Pipe ................................................ 035,123
Plumbing .......................................... 051,133,134,135
Pollution .................................................. 058,059
Precipitation ................................................. 009
Pressure Tests ............................................. 019
Protection ........................... ...................... 153
103
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"R" Number
Rainfall 049,052,053,058,108
Relining 110
Regulations 114
Repairs 080,082,109,122,132
Roots 021,063,064,065,076,084,087,093
Rubber Rings 107,
Runoff 004,009,010,011,047,049,054,108,120
Runoff Detention Oil
"S"
Safety 068
Salt Water Intrusion 062
Sanitary Sewers 007,023,025,027,038,109
Sealing 092,094
Sewer Cleaning 068
Sewer Repair 110
Sewer Separation 005
Sewer Stability 075
Sewered Areas & Population 005
Smoke Tests 061,071
Soils 004,006,036,049,053,117,124
Specifications 002
Steel Pipe 112
Storm Drainage 010,011
Storm Sewers 018,027,109
Surcharge 030
Surveillance 056
Sutro Weirs 020
4fT>>»
Tests 026,029,055,056,069,073,125
Truss Pipe 123
TV Inspection 070,073,074,077,079,080,081,082
083,088,090,096,097,100,105,106
104
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BIBLIOGRAPHY
001 PORTABLE WEIRS FOR PRECISE
INFILTRATION MEASUREMENTS.
S. B. Birch, Jr.
Public Works, vol 93, no 5, pp 91-92, May 1962
Descriptors: Flow Measurements
Improved and modern portable device for measuring
infiltration.
002 REPORT ON INFILTRATION IN SANITARY
SEWERS
APWA
Northern California Chapter, Oakland, 28 pp, 1955
Descriptors: Construction, Design, Specifications
Review of methods of design, construction,
inspection and testing practices.
003 THE COLLECTION, TREATMENT AND
DISPOSAL OF THE SEWERAGE OF CENTRAL
COSTA COUNTY, CALIFORNIA
Brown and Caldwell, Civil and Chemical Engineers
Chapter 10: Storm Infiltration, 1956
Descriptors: Air Testing, Economics, House
Connections, Photography.
Discussion effect of storm infiltration on sanitary
sewer systems in San Francisco Bay Area.
Experiences, testing, inspection and corrective action
are discussed. Role of house connection is reviewed.
Costs are given.
004 SEEPAGE INTO DRAIN TUBES IN
STRATIFIED SOIL
D. Kirkham
American Geophysical Union (trans) Col. 32, no 3;
pp 422-443, June 1951
Descriptors: Runoff, Soils
Expressions of drain flow, surface inflow distribution,
and flow nets are derived for surface water seeping
into drain tubes embedded in water saturated soil
consisting of two horizontal strata of different
permeabilities; it is shown that lower layer governs
flow; quantitative results are worked out for several
cases, including flow nets; both drains in and below
surface stratum considered.
005 PROBLEMS OF COMBINED SEWER
FACILITIES AND OVERFLOWS
U. S. Federal Water Quality Administration
Water Pollution Control Series WP-20-11, Prepared by
APWA under contract no 14-12-65.
Descriptors: Bypasses, Combined Sewers,
Control/Treatment Methods, Infiltration Overflows,
Sewered Areas & Populations, Sewer Separation
The effects and means of correcting combined sewer
overflows and separate storm and sanitary sewer
discharges were inventoried on a national basis in
1967 and compiled in this report. On-site personal
interviews with the public officials of approximately
900 communities in the United States collected over
250,000 pieces of data which have been analyzed and
grouped by state, river basin, and population group to
define the problems of combined sewers, overflow
locations, type and number of regulators, associated
land and water uses, estimates of costs for sewer
separation by states, alternate control and/or
treatment methods, and consideration of other
aspects of the overall problem. Findings, Conclusions
and Recommendations are presented in summary
form.
006 JOINTING METHODS FOR VITRIFIED CLAY
PIPE
J. Sirret
The Municipal Utilities Magazine, pp 32, 41,
February 1957
Descriptors: Clay Pipe, Joints
A brief review of their current joints for clay pipe.
007 ECONOMIC CONSIDERATIONS FOR
SANITARY SEWERS
C. H. Lawrence
Public Works, vol 98, no 3; pp 99-102, March 1967
Descriptors: Economics, Sanitary Sewers
Total capital investment for overall sewerage system
is typically in order of $200/capita of which
three-fourths represents collection system and
one-fourths treatment and disposal facilities; Included
are tabulations of construction costs for lateral sewers
105
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of differing materials and influence of sewer life and
future infiltration on sewer economy, in sulfide
troubled areas, partial replacement is usually
required; competitive gaps between pipes made of
various materials are narrowed; economics of sewer
replacement are considered.
008 ARE YOU TREATING INFILTRATION?
T. T. Hay
Wastes Engineering, vol 25, no 3; pp 121-124, 147,
March 1954
Descriptors: Excess Flow, Infiltration
...infiltration accounts for 40 percent of total
(discharge) flow in Racine, Wisconsin, ...1951.
009 ANNUAL RUNOFF IN UNITED STATES
W. B. Langbein, et al
U. S. Geological Survey, cir. no 52, 14 pp; 1 map,
June 1949
Descriptors: Precipitation, Runoff
Development of maps of annual runoff, (US)
preparation....; data on mean runoff, precipitation,
and evapo-transpiration; effect of climate, geology,
topography, size of dfainage area, and vegetation on
runoff. (Bibliography)
010 SURFACE WATER DRAINAGE - REVIEW OF
PAST RESEARCH
L. H. Watkins
Institution of Municipal Engineer Journal, vol 78, no
4; pp 301-320, February 1951
Descriptors: Percolation, Runoff, Storm Drainage
Critical review of principal investigations carried out
on drainage in England and United States; ... local
records kept over many years; ... curves showing
amount of infiltration. (Bibliography)
Oil SURFACE DETENTION, RATE OF RUNOFF
LAND USE, AND EROSION RELATIONSHIPS ON
SMALL WATERSHEDS.
L. Schiff
American Geographical Union (trans), vol 32, no 1,
pp 57-65, February 1951
Descriptors: Percolation, Runoff, Runoff Detention,
Storm Drainage
Relationships between rate of surface runoff and
surface detention are developed and represented by
equation; infiltration curves are derived for small
watersheds.
012 SEWER CAPACITY, DISCHARGE RATES,
INFILTRATION, TRADE WASTES
J. B. Porter
Commonwealth Engineer, May 1, 1950, pp 402-404
Descriptors: Design, Flow Measurement, Industrial
Waste, Infiltration
Discussion of the various factors involved in
determining capacity of main sewers in rapidly
developing areas.
013 SEWER JOINTS AND MATERIALS
C. A. Johnson
APWA Yearbook 1959, pp 186, 187
Descriptors: Joints
Review of experiences with a few types of sewer pipe
joints.
014 RUBBER COUPLING FOR PIPES
J. Kunnen
Engineering, vol 177, no 4601; p 446, April 2, 1954
Descriptors: Joints
Rubber cylinder which fits inside ends of two pipes
to be joined; under testing, coupling withstood
pressure of 475 psi successfully.
015 FINAL REPORT ON STUDY OF
WATERTIGHT DRAINAGE PIPE UNITS
U. S. Engineers Dept., Savannah, Georgia, 1955,
catalogue no 621A21U
Descriptors: Joints
Description of study and findings.
106
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016 INFILTRATION SPECIFICATIONS AND
TESTS
C. R. Velzy, T. M. Sprague
Sewage and Industrial Wastes, vol 27, no 3; pp
245-254; discussion pp 254-56, March 1955
Descriptors: Control Practice, Infiltration Tests,
Joints
Experience with sewer joints and leakage. How
infiltration on sanitary . sewers can be kept to
reasonable minimum. Tests proved that it is possible
to obtain acceptable joints with rubber ring joints on
concrete and asbestos cement pipe and with
hot-poured joints on vitrified tile.
017 CLAY PIPE ENGINEERING MANUAL
Clay Sewer Pipe Association, Incorporated,
Columbus, Ohio
Descriptors: Bedding, Construction Procedures,
Design
Data on design, and construction of sewer layout,
storm sewers and sewer pipe and drains.
018 CORRECTING STORMWATER AND
INFILTRATION, TONAWANDA, NEW YORK
N. L. Nussbaumer
Sewage and Industrial Wastes, vol 28, no 8; pp
977-982, August 1950
Descriptors: Combined Sewers, Storm Sewers
Design of drainage projects based jon system of storm
sewers deep enough to intercept surcharged storm
flow from sanitary sewers, and connected to existing
storm sewer outlets.
019 NEW DATA ON SEWER INFILTRATION -
EXFILTRATION RATIOS
S. Barland
Public Works, vol 87, no 9; pp 97-98, September
1956
Descriptors: Exfiltration, Infiltration Tests, Pressure
Tests
Recent findings ... on unfiltered water in sewer lines
give help in evaluating testing data: infiltration test,
exfiltration or internal pressure tests, further tests to
ascertain if proportionate ratio might exist between
infiltration and exfiltration in testing.
020 INFILTRATION MEASUREMENTS IN
SEWERS OF SMALL SIZE
R. A. Lincoln
American Society of Civil Engineers - proc; (Journal
of Sanitary Engineering Div.), vol 83, no SA2, paper
no 1203; 9 pp
Descriptors: Infiltration, Sutro Weirs
Rapid and accurate method of measuring
groundwater infiltration flows on newly constructed
sanitary sewers of small size.
021 STUDY OF RESISTANCE OF SEWER PIPE
JOINTING MATERIAL TO ENTRY OF TREE
ROOTS
C. E. Keefer
Water and Sewage Works, vol 104, no 3;pp 128-129,
March 1957
Descriptors: Roots, Joints
Joints made of mixture of clay and rock salt do not
prevent entry of tree roots. Tests with CPO-2
bitumastic compound were not entirely successful;
there were no roots in any of cement joints, copper
joints, G-K compound joints (including those) that
had been previously primed with G-K primer.
022 SMALL-SIZE PIPE FOR SANITARY LATERAL
SEWER
Building Research Advisory Board, Federal Housing
Administration, contract no Ha-fh-646; February 28,
1957
Building Research Institute: Washington, D.C., May
1957
Descriptors: Design
The problem can be stated in the form of three
questions: 1) What is the acceptable minimum size
pipe... in street sanitary sewers in residential areas? 2)
What conditions should be attached...? 3) What
appropriate recommendations should be made with
good design, construction and maintenance
practices...?
107
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023 VARIATION OF SEWAGE FLOW IN
COLLEGE TOWN
G. D. Hutchinson; E. R. Baumann
Sewage and Industrial Wastes, vol 30, no 2; pp
157-163, February 1958
Descriptors: Flow Measurement, Sanitary Sewer
Sewage flow study was made of City of Ames, Iowa
with population of 27,000; study demonstrates need
for nationwide seepage flow study in cities of various
sizes; study indicates that week's study of hourly
flow variation might portray sewage flow as well as
year's study.
024 DESIGN AND CONSTRUCTION OF
SANITARY AND STORM SEWERS
American Society of Civil Engineers and Water
Pollution Control Federation, New York, 1969.
(ASCE Manual of Engineering Practice No. 37, WPCF
Manual of Practice No.9.)
Descriptors: Construction, Design
Manual of recommended practice.
025 VITRIFIED CLAY PIPE ENGINEERS'
HANDBOOK
Southern Clay Pipe Institute, Atlanta, Georgia, 1960
Descriptors: Clay Pipe, Design, Installation, Sanitary
Sewers
...manual on the use and installation of clay pipe
and.... products.... to those engaged in the design and
construction of sewerage systems, drains and others.
026 EXPERIENCE WITH PRECAST SEWER
JOINTS
T. R. Murray
Public Works, vol 93, no 9; pp 131-132, September
1962
Descriptors: Joints, Tests
Infiltration tests by constructing circular diaphragm
or bulkhead with 2-inch pipe through center and
installing diaphragm at downstream end of sewer
using expansible rubber gasket around perimeter to
secure watertight seal in pipe; tests showed that
precast joints and continuous granular bedding
represent substantial improvement in underground
pipe line design.
027 CONCRETE PIPE FIELD MANUAL
H. F. Peckworth
American Concrete Pipe Association; Chicago, 1962,
catalogue no 666.993 Z621
Descriptors: Concrete Pipe, Design, Installation,
Sanitary Sewers, Storm Sewers
Sanitary sewer pipe, culverts, pressure water pipe
drain tile and storm sewer; factors affecting strength;
sanitary sewer design data; design of storm sewers and
culverts, plus information relating to all of the above.
028 ESTIMATION OF DESIGN MAXIMUM
DOMESTIC SEWAGE FLOW RATES
J. J. Leute
Sanitary & Municipal Engineering, John Hopkins
University, order no 64-365; vol. 202 pp 925, 1963
Descriptors: Design, Flow Measurements
While hydraulic design procedures for sanitary
sewerage systems are usually straightforward,
determination of the flows for which design is to be
carried out is often done by application of unprecise
rules of thumb. The results from up to two years of
continuous sewer gaugings from seven study areas in
four cities in the .... U.S. are used to develop a
method for estimating the qualities of flow due
separately to domestic sewage, to infiltration and to
exfiltration a method is developed.... to estimate
the maximum rate of domestic sewage flow.... during
a selected design period. The reliability is studied...
and techniques are shown whereby the... estimate
may be adjusted... to allow for uncertainty. An
illustrative example is shown....
029 LOW PRESSURE AIR TEST FOR SANITARY
SEWERS
R. E. Ramseier, G. C. Riek
ASCE-proc. (Journal of Sanitary Engineering Div.)
vol 90, no SA2; pt 2, paper 3883; pp 1-29, April
1964
Descriptors: Air Testing, Clay Pipe, Tests
108
-------
Effect of moisture on permeability of vitrified clay
sewer pipe and its effects on testing procedure; ...field
tests show that pipe without detectable failure will
lose less than 0.003 cubic feet of air/min/sq ft of
internal pipe surface and that any air loss exceeding 2
cuft/min can be located.
030 THE INFILTRATION OF GROUND WATER
INTO SOIL SEWERS
D.R. Smith, J.A.Clifford
The Chartered Municipal Engineer, vol 90, pp
169-175, June 1963
Descriptors: Economics, Flow Measurements, Ground
Water, Infiltration, Surcharge
A result of three years of investigation into
infiltration, its causes and effects. Flow
measurements, economics and remedial measures are
discussed.
032 SURVEY OF EXPANSION JOINTS FOR
PIPEWORK SYSTEMS
M.Neal
Engineering Materials and Design, vol 8, no 3; pp
168-175, March 1965; vol.8, no 4; pp 240-245, April
1965
Descriptors: Joints
Respective advantages of rubber expansion joints, slip
joints, and various forms of bellows joint and surveys
units currently available.
033 MUNICIPAL REQUIREMENTS FOR SEWER
INFILTRATION
Public Works, pp 158-162, June 1965
Descriptors: Design, Infiltration
Feedback of a questionnaire filled out by
municipalities. Questions deal with what infiltration
equation did each community use.
034 WATERTIGHT SEWER BUILT UNDER
DIFFICULT CONDITIONS
R. Pelishek
Public Works, p 84, September 1965
Descriptors: Construction, Joints
Description of rubber joint gaskets used in difficult
soil and water conditions.
035 UNDERGROUND DRAINAGE AND SEWER
PIPES IN THIN RIGID PVC
British Plastics, vol 39, no 10; pp 577-578, October
1966
Descriptors: Joints, Plastic Pipes
Use of rubber ring sealed socket-joint for pipe
connection; testing...; advantages... even... when
dealing with aggressive sewage, soils....
036 SOIL CHEMICAL CHANGES AND
INFILTRATION RATE REDUCTION UNDER
SEWAGE SPREADING
031 SEWER DESIGN - INFILTRATION
DETECTION AND CORRECTION
B. J. Haney
L.S.U. - Engineering Research Station, bulletin 83,
pp 55-71,1965
Descriptors: Design, Infiltration
Calculation of capacity of sewer system sizing of
pipe, determination of pipe slope, selection of pipe
material, and proper installation of pipe as basic steps
in design of gravity sewer system.
R. E. Thomas, W. A. Schwartz, T. W. Bendixen
Soil Science Society of America, proc., vol 30, no 5;
pp 641-646, Sept.-Oct. 1966
Descriptors: Infiltration, Soils
Laboratory and field lysimeters were used to
investigate site and nature of soil-pore clogging under
sewage spreading; site of clogging was located by
determining with 'sewage meter impedance profile at
0.5 cm depth intervals; soil samples were analyzed for
sulfide, iron, phosphate, total organic matter,
polysaccharide, and polyuromide to evaluate possible
causative relationships.
109
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037 CONCRETE PIPES - REVIEW OF RECENT
DEVELOPMENTS IN GREAT BRITAIN AND
SOME PROBLEMS ENCOUNTERED
N.W.B. Clarke
International Congress of Precast Concrete Industry,
5thproc.;pp 117-124 May 21-26, 1966
Descriptors: Concrete Pipe
Problems encountered and experience obtained in
design of rigid underground pipes in Great Britain
during past 10 years are reviewed, particularly
regarding flexible joints, pipe beddings, site work and
impact factors; comparative impact and bedding
factors are shown in tables.
038 AN EVALUATION OF THE PROBLEMS OF
SANITARY SEWER DESIGN
J. C. Geyer, J. J. Lentz
Water Pollution Control Federation, vol 38, no 7; p
1138, July 1966
Descriptors: Design, Sanitary Sewers
General problems facing sewer designers have been
studied using field data collected in four United
States communities. Analysis of these data indicates
that basic causes of maintenance difficulties are tree
roots, accumulations of debris in the absence of
roots, other causes, and in areas having cohesionless
sub-soil, sewer cave-ins. Proportionately fewer
blockages occur when grades are moderate, and
proportionately more occur at the upper terminals of
the sewers. In 8-inch pipe, manhole spacing has little
effect on the labor costs of stoppage relief. Emphasis
is placed on statistical techniques for estimating
domestic sewage flow. Flow of rainwater and
groundwater was at times found to be excessive in all
systems ^studied. Limited data on costs of operating
and maintaining sewage pumping stations are
reported and evaluated.
039 PIPE JOINT BAFFLES ROOTS IN FIVE YEAR
TEST
Public Works, p 130, July 1966
Descriptors: Concrete Pipe, Joints
U. S. Concrete Pipe Co. laid a 4-inch vitrified clay line
to test for root intrusion. The results were very
favorable to the pipe.
040 DESIGN CONSIDERATIONS FOR SEWER
PIPES MADE FROM RIGID MATERIALS
K. E. Seal, M. V. Mountford
New Zealand Engineering, vol 23, no 3, pp 280-298,
July 1968
Descriptors: Asbestos-Cement Pipe, Clay Pipe,
Concrete Pipe, Design, Joints
A detailed mathematical analysis of pipe stresses and
strength when laid in ground. Discusses joints,
bedding and various types of failure.
041 PIPE JOINTS LIMIT INFILTRATION
G. W. Clark, Jr., M. L. Leyrer
Civil Engineering, New York, vol 37, no 1; pp 62-63,
January 1967
Descriptors: Groundwater, Joints
City engineers in Muskegon, Michigan designed
sanitary sewer trunk that would be placed in area
having high water table; limiting infiltration was most
important.
042 INFILTRATION AND SEWER FOUNDATIONS
T. W. MacDonald, J. K. Mayer, S. E. Steimle
Public Works, vol 98, no 12; pp 105-107, December
1967
Descriptors: Bedding, Foundation
Study was initiated to determine most suitable
foundation materials and best types of sewer
arrangements, under various conditions, which will
effectively decrease and control infiltration in Gulf
Coast area, and to test various foundation materials
and arrangements in combination with various laying
conditions in order to determine most suitable
bedding in number of soil types common to area.
043 LOW PRESSURE AIR TESTING OF SEWERS
T. P. Schacher
Public Works, pp 103-104, 150, December 1967
Descriptors: Air Testing
A mathematical but practical approach using Boyle's
Law.
110
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044 WHEN SHOULD NEW SEWERS BE
PHOTOGRAPHED?
R. E. Falardeau
Public Works, p 148, April 1968
Descriptors: Construction, Photography
Writer feels new sewers should be inspected by
photography as soon after construction as possible.
045 EXFILTRATION TESTING OF LARGE
SEWERS IN KANSAS CITY, MISSOURI
J. F. Nadung, L. W. Weller
Water and Wastes Engineering, vol 4, no 9; pp 87-89,
September 1967
Descriptors: Concrete Pipe, Exfiltration Test
Test results discussed are for sewers constructed of
reinforced concrete pipe, with manholes included in
test sections; exfiltration specification used permits (a
certain) leakage; data are presented...; exfiltration
test-conditions and results are summarized.
046 PUT INTERCEPTOR ON LAKE BOTTOM
American City, vol 83, no 9; pp 129-130, September
1968
Descriptors: Interceptor, Joints
Design and method of placing of unusual interceptor
sewer around scenic Lake Sammamish in
Metropolitan Seattle, Washington; method avoids
trench excavation; sewer is submerged, lying on lake
bottom; special bottle-tight joints make this possible,
unusual feature of interceptor is design of its access
manholes, portable aluminum shaft that can be
lowered to seat on sealed, submerged manhole....
047 HOW TO ESTIMATE STORM WATER
QUANTITIES
H. M. Gifft, G. E. Symons
Water and Wastes Engineering, vol 5, no 3;pp 46-50,
March 1968
Descriptors: Design, Runoff
Several factors involved in determining quantities of
storm water are discussed for storm sewer design as
related to rainfall and runoff; derivation of formulas
for calculation of drainage area shape, rainfall
intensity — frequency date, time of concentration
and coefficient of runoff; nomograph for
determining... time of flow.
048 AIR TESTING SEWERS
S. H. Hobbs, L. G. Cherne
Journal of the Water Pollution Control Federation,
vol 40, no 4; p 636, March 1968
Descriptors: Air Testing
For location of leakage and control of infiltration or
exfiltration. Bloomington, Minnesota, sewers were
checked with the air testing methods which were
stated to be faster and more economical... used in
construction, sewer service, and repair...
049 RUNOFF ESTIMATES BASED ON
INFILTRATION CAPACITY, ANTECEDENT
MOISTURE CONDITIONS AND PRECIPITATION
R. G. Andrews
Agricultural Engineering, vol 31, no 1, pp 26-28,
January 1950
Descriptors: Rainfall, Runoff, Soils
A discussion of a method for estimating runoff based
on the infiltration method. Infiltration capacity is
defined as the rate at which infiltration would take
place at any instant were the supply to equal or
exceed this capacity.
050 EXPERIENCE AND RESEARCH WITH
ASBESTOS-CEMENT PIPES BURIED IN
VICTORIAN CLAYS
J.E. Holland, G. Kassaff
Asian Regional Conference on Soil Mechanics and
Foundation Engineering, 3rd proc., vol 1; pp 94-98,
September 25-28, 1967
Descriptors: Asbestos Cement Pipe, Clay Soils
In some of expansive-clay areas of Victoria, Australia,
occasional transverse failures of asbestos-cement pipes
occurred...; to overcome these failures, ...research
program (was) undertaken... indicating that failure
mechanism, responsible for breakage, results from
uneven longitudinal bending due to differential
swelling of the soil surrounding the pipes; methods of
allowing for, or reducing these effects are indicated.
Ill
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051 PIPING HANDBOOK
R. C. King
McGraw Hill, New York, 5th ed., 1967
Descriptors: Corrosion, Design, Plumbing
Authoritative and accessible data ... in piping design.
... the design of sewerage systems (is) dealt with.
Some chapters deal with physical and metallurgical
properties of piping material, corrosion,
sewerage-systems piping, plumbing systems.
052 NEW TECHNIQUES FOR THE DETECTION
OF DEFECTIVE SEWERS
K. W. Brown and D. H. Caldwell
Sewage and Industrial Wastes, Vol. 29, no 9, pp
963-977, 1957
Descriptors: Air Testing, Infiltration, Rainfall
Description of methods used to determine defects in
sanitary sewers which are subject to infiltration.
Photographic methods and air testing techniques are
discussed.
053 LABORATORY INVESTIGATIONS OF SOIL
INFILTRATION THROUGH PIPE JOINTS
E. H. Nettles, N. B. Schomaker
National Research Council — Highway Research
Board - Research Record, no 203; pp 37-56, 1967
Descriptors: Infiltration, Joints, Permeability, Soils
Investigation of infiltration characteristics of four
soils - poorly graded medium to fine sand, uniformly
graded fine sand, silt, and lean clay, to develop
system of classifying soil according to degree that
infiltration through pipe-joint openings may be
expected to occur; investigation included design and
construction of model simulating prototype pipe
joint, study of feasibility of using model for such
studies, investigation of variables affecting soil
infiltration, and investigation of filtration of soils
described.
054 SEWAGE FLOW INVESTIGATIONS AT
INVERCARGILL
J. S. Roberts
Proceedings, New Zealand Institution of Engineers,
vol 37, pp 286-39, 1950
Descriptors: Flow Measurement, Rainfall, Runoff
A detailed paper on sewage flow measurement
correlated with rainfall and infiltration.
055 MILWAUKEE TESTS NEW JOINTS FOR
SEWER PIPE
Robert A. Burmeister
APWA Reporter; pp 6-12, December 1962
Descriptors: Joints, Tests
City of Milwaukee has recently completed a series of
tests on new joints. Also a new testing procedure was
developed and evaluated.
056 ELIMINATION OF STORM WATER FOR
SANITARY SEWERS AT WADSWORTH, OHIO
F. G. Randall
Sewage Works Journal, vol 21, no 2; pp 332-333,
March 1949
Descriptors: Inflow, Surveillance, Tests
Rubber balls dropped into downspouts to detect
whether or not sanitary sewers were misused by
leading storm water into them; report on inspection
procedure...
057 REDUCTION OF EXCESS SEWAGE FLOWS
AT MILWAUKEE
R. D. Leavy
Sewage and Industrial Wastes, vol 26, no 1; pp 34-41,
January 1954
Descriptors: Infiltration, Inflow
Storm water finds its way into sanitary sewers by one
or more of methods discussed; infiltration,
foundation drains, roof downspouts, surface water,
cross connections and inadequate drainage basin
capacity; methods of reducing excessive flow in
intercepting sewers...
058 EQUIPMENT: METHODS, AND RESULTS
FOR WASHINGTON, D.C., COMBINED SEWER
OVERFLOW STUDIES
112
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C. F.Johnson
Water Pollution Control Federation Journal, vol 33,
no 7, pp 721-733, July 1961
Descriptors: Combined Sewers, Overflows, Pollution,
Rainfall
Details and comments on combined sewer
investigation in Washington, D.C. Rainfall correlation
is given.
059 STORM WATER AND COMBINED SEWAGE
OVERFLOWS
S. A. Greely, P. E. Langdon
ASCE proc. (Journal of Sanitary Engineering
Division), vol 87, NSAI; pt. 1; paper 2718; pp 57-68,
January 1961
Descriptors: Combined Sewers, Overflows, Pollution
Aspects of abatement of pollution due to overflows
resulting from rainstorms of combined sewer systems
of older cities; restriction of overflows by
intercepting sewers; treatment of intercepted flow,
elimination of combined sewage overflows by
construction of new system of sanitary sewers for
complete separation.
060 RESIDENTIAL USE AND MISUSE OF
SANITARY SEWERS
connected to sanitary sewer system in South
Charleston, West Virginia; smoke was applied in
manhole by lighting smoke bomb on suction side of
blower and discharging it through manhole into
sewer.
062 SALT WATER IN THE SEWERS
F.J. Miller
American City, pp 112, 136, December 1965
Descriptors: Salt Water Intrusion
In North Miami, Florida, salt water was infiltrating
the fresh-water supply. The solution was in the waste
treatment, and not its conveyance.
063 THIS NOT THIS
R. B. Moffitt
Brick and Clay Record, vol 142, no 6, pp 55-57, 76,
June 1963
Descriptors: Copper-Ceramic Tile, Copper Sulphate,
Roots
Description of experience in retarding root growth in
drainage pipe by the use of various forms of metallic
and compounds of copper.
064 NEW CAULKING MATERIAL FOR SEWERS
G. S. Bell
Water Pollution Control Federation Journal, vol 35,
no 1; pp 94-99, January 1963
Descriptors: House Connections, Inflow
Discussion of effect of poor house connection
construction and illicit connections.
061 "SMOKING OUT" ILLEGAL HOUSE DRAINS
A. Larmon
Wastes Engineering, vol 34, no 11; p 603, November
1963
Descriptors: Inflow, Smoke Tests
Smoke testing equipment consists of portable 1500
c/m Homelite blower, connected by canvas air-duct
to sheet of %-inch plywood lined with sponge rubber
to fit over manhole was used to locate downspouts
R. m. Starns, Jr.
Western Construction, vol 29, no 5, pp 58-60, 122,
May 1954
Descriptors: Caulking, Joints, Leakage
Description of a self-sealing jointing product used on
California projects.
065 INVENTORY OF COMBINED SEWER
FACILITIES
R. H. Sullivan
Civil Engineering, vol 38; pp 52-53, November 1968
Descriptors: Combined Sewers
A brief description of the 1967 Inventory of
Combined Sewer Overflow Facilities conducted by
the American Public Works Association for the
FWPCA.
113
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066 CONTROLLING ROOTS IN SEWERS BY
COPPER SULPHATE
J. W. Wood
AMERICAN PUBLIC WORKS ASSOCIATION,
special report no 5, Chicago; 2 pp., 1948
Descriptors: Copper Sulphate, Roots
Discussion of use of Copper Sulphate and its
effectiveness.
067 COPPER SULPHATE FOR ROOT AND
FUNGUS CONTROL IN SANITARY SEWERS AND
STORM DRAINS
J. W. Hood
Phelps Dodge Refining Corp., 40 Wall Street, New
York,21pp.(illus.), 1949
Descriptors: Copper Sulphate, Roots
Data on damages caused by roots and fungus in
sanitary sewers and storm drains such as mechanical
obstruction of pipes, odor nuisance, deterioration of
structures, reduction in capacity of facilities and
sewage treatment difficulties and resultant increase in
stream pollution; application of Copper Sulphate and
its effects.
068 SEWER CLEANING AND SAFETY
MEASURES
N. W. Nester
Water and Sewage Works, vol 105, no 10; pp
420-424, October 1958
Descriptors: Maintenance, Safety, Sewer Cleaning
Causes of sewer stoppages, methods of cleaning
sewers...
069 "LAUGHING GAS" SHOWS VALUE IN
SPOTTING PIPELINE LEAKS
J. E. Kaufman
Oil and Gas Journal, vol 58, no 8; pp 100-102,
February 22, 1960
Descriptors: "Laughing Gas," Nitrous Oxide, Tests
Laboratory tests demonstrate feasibility of nitrous
oxide tracer gas in hydrostatic testing of underground
lines; as little as 2 ppm of nitrous oxide at surface of
ground can be detected by infrared analyzer.
070 HOLLYWOOD LICKED INFILTRATION -
BEFORE IT LICKED HOLLYWOOD, (FLORIDA)
J. W. Watson
Wastes Engineering, vol 32, no 8; pp 397-399, August
1961
Descriptors: Grouting, Joints, Leak Detection,
Photography, TV Inspection
Description of location of leaks in sewers by
photographic method and closed circuit TV and
repair by internal chemical sealing and external
cement grouting.
071 SEWER LEAKS LOCATED BY SMOKE
J. R. Stallings, Jr.
Civil Engineering, New York, col 32, no 9; p 39,
September 1962
Descriptors: Leak Detection, Smoke Tests
Method and procedure for location of major leaks in
sewer systems used to solve excessive infiltration
problems at Forbes Air Force Base near Topeka,
Kansas; smoke tests with portable 1500 cfm Homelite
blower with canvas air duct; smoke is applied by
isolating section of sewer by sandbagging in sewer
manholes.
072 CHEMICAL SEAL STOPS SEWER
INFILTRATION
F. D. Dahlmeyer
Public Works, vol 93, no 11; pp 91-92
Descriptors: Joints, Sealant
Treatment process to stabilize and waterproof soil
surrounding sewer line by introduction of chemical
grout which, after exposure to catalyst solution forms
stiff gel that is impermeable to water; tests before and
after treatment proved advantages of method which
avoids problems of open excavations.
114
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073 A FOUR-WAY PROGRAM OF SEWER
REHABILITATION
E. J. Baugh
American City, p 117, March 1964
Descriptors: Maintenance, Tests, TV Inspection
1) Cleaning all sewers on a year-round basis; 2) TV
inspection; 3) dye-testing from downspouts and
sanitary connections to pinpoint illegal sanitary and
storm connections; 4) repair or replacement of faulty
sewers.
074 KNOW WHEN TO HOLLER FOR HELP
R. Brubacher
American City, pp 92-93, May 1964
Descriptors: TV Inspection
TV inspection in sewer spots infiltration
075 A SEARCH TO SOLVE THE SINKING SEWER
PROBLEM
American City, p 38, May 1965
Descriptors: Sewer Stability
Through field and laboratory tests... an answer to the
sinking sewer problem in the Gulf Coast Region...
and... a... study of infiltration will be attempted.
076 NO NEED FOR EMERGENCIES IN THIS
STEPPED-UP SEWER-CLEANING AND
MAINTENANCE PROGRAM
J. M. Dick
American City, vol 79, no 5; pp 103-104, May 1964
Descriptors: Maintenance, Roots
Solution of stoppage problems in Dearborn, Michigan
sewer system where lack of rain and continuing drop
of water table caused tree roots to seek moisture
from sewers;... continuous rodders keep 4 sets of
bucket machines with truck loaders in operation and
average approximately additional 1500 ft./day
root-cutting.
077 SEAL SEWER LEAKS FROM THE INSIDE
R. Nooe
American City, pp 91-92, June 1964
Descriptors: Sealing, TV Inspection
Repairing sewers without digging will save Fort
Myers, Florida, around $2,000,000. in the next 20
years. Television inspection and internal sealing of
leaks.
078 LOOK RIGHT INTO YOUR SEWER
PROBLEMS
J. A. Kern
American City, pp 81-85, August 1964
Descriptors: TV Inspection
Closed-circuit television in Manheim Township,
Pennsylvania (revealing infiltration and inflow.)
079 ISOLATING THE CAUSES OF INFILTRATION
A. T. Brokaw
American City, p 80, December 1964
Descriptors: Illicit Connections, Inflow, Photography
Princeton, New Jersey,... is... stopping complaints
about flooded basements and other irritations with
sewer photography, house inspection and other
controls...
080 SEWERS CAN BE REBUILT BY REMOTE
CONTROL
G. Rutz
Water Works and Wastes Engineering vol 2, no 10; p
42,1965
Descriptors: Repairs, TV Inspection
Locating points of infiltration with closed circuit
(TV) before repair operations.
081 CATCHING UP ON DEFERRED
MAINTENANCE AT KANSAS CITY, MISSOURI
G. T. Hopkins, 0. C. Hopkins, F. L. Kramer
Water Pollution Control Federation, vol 37, no 2; p
236, February 1965
115
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Descriptors: Maintenance, TV Inspection
086 SEWER INSPECTION AND MAINTENANCE
Description of program of maintenance and testing
for illicit connections and repairs.
082 TV PLUS GROUT
American City, pp 112-113, April 1965
Descriptors: Grouting, Repairs, TV Inspection
Indianapolis' leaking sewer system was detected with
TV and corrected with grout.
083 GROUTING TECHNIQUE CUTS SEWER
REPAIR COSTS
R. H. Batterman
Public Works, pp 102-103, May 1965
Descriptors: Grouting, TV Inspection
Grouting machine follows TV camera in sewer.
084 SOIL FUMIGANTS CONTROL ROOTS IN
SEWERS
G. Z. Rayner
American City, pp 135-136, June 1965
Descriptors: Roots
Milwaukee has developed a way to make sewers
root-free for at least two years, using a chemical
foam.
085 AN UNUSUAL PHOTOGRAPHIC PIPELINE
SURVEY
G. P. Fulton
Public Works, pp 85-87, July 1965
Descriptors: Inspection, Photography
Walk-through inspection was ruled out; survey
equipment included camera and strobe flashlight
mounted on float connected by cable to two
countenveighted canisters holding additional strobe
lights... lowered into downstream end of sewer reach
and attached to coaxial cable running to next
upstream manhole; pictures were taken at 5 foot
intervals.
J. R. Finn
Public Works, p 150, October 1965
Descriptors: Inspection, Maintenance
Common ills with sewers, methods of inspection, and
protective measures.
087 THE MODERN WAY TO INSPECT AND
REPAIR SEWERS
T. W. Clapham
Public Works, pp 90-92, December 1965
Descriptors: Inspection, Repairs
Grouting and TV technique in Little Rock Arkansas
088 TV PROVES USEFUL FOR SEWER
INSPECTION
R. H. Hayes
Civil Engineering, vol 36; pp 66-68, January 1966
Descriptors: TV Inspection
Description of examples of TV inspection techniques
in sewers.
089 PHOTOGRAPHIC SEWER INSPECTIONS
REQUIRED BY ORDINANCE
R. E. Falardeau
Public Works, pp 93-95, March 1966
Descriptors: Inspection, Photography
Result: a film library of the entire sewer system, and
improved maintenance.
090 SEATTLE'S TV SEWER INSPECTION SYSTEM
H. T. Thornqujst
Water and Sewage Works, vol 113, no 3; pp 82-83
Descriptors: TV Inspection
Winch truck provides mechanical means of pulling
camera through sewer...
116
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091 SEWER INSPECTION PHOTOGRAPHS CAN
RESOLVE CONTROVERSIES
R. E. Falardeau
Public Works, p 118, December 1966
Descriptors: Inspection, Photography
Problems and procedures in interpreting the
photographs; a concensus of professional engineers is
best.
092 EVALUATION OF EXTERNAL SEALING
METHOD TO REDUCE STORM FLOW EFFECTS
IN SEWERAGE SYSTEMS,
Final Progress Report
FWPCA Demonstration Grant WPD 111-01-66,
County of Sonoma, California, Sanitation
Department
Project Director — Donald B. Head, Sanitary Engineer
Descriptors: Asphalt Compounds, Joints, Sealing
Test of new methods of external sealing with
asphaltic compounds. Equipment developed and
correlation between infiltration and exfiltration
pursued. Correlation with rainfall also developed.
093 CONTROL OF SEWER ROOT PROBLEMS
WITH COPPER SULPHATE
R. Marshall
Public Works;pp 110-112, April 1967
Descriptors: Copper Sulphate, Roots
Engineering approach to the problem, plus
considerations and methods of dealing with the
public when, for example, a municipal worker had to
enter a home, as the job required.
094 SEALING PROCESS RESOLVES
INFILTRATION PROBLEM
S. G. Stepp
Public Works; pp 70-73, July 1967
Descriptors: Joints, Sealing
At St. Augustine, infiltration problems were
compounded by the closely built old buildings in
some sections of the city. Listed are all the
approaches considered, the description of the job and
the results.
095 INVENTION PROTECTS HOMES FROM
BACKWATER DAMAGE
W. C. Dalton
Public Works; pp 137-139. October 1967
Descriptors: Backwater Protection
Wherever lowest waste drainage connection of
building is below point of relief on colector sewer,
danger of backwater damage exists unless precautions
are provided; developed emergency backwater
overflow device is self-sealing ball float valve with
nose cone deflector; sectional view of original device,
and one of new design.
096 TV INSPECTION AND IN-PLACE GROUTING
OF SEWERS
R. H. White
Water and Wastes Engineering, vol 5, no 9; p 72, 1968
Descriptors: Grouting, Joints, TV Inspection
Austin, Texas, used TV camera inspection to identify
and locate broken pipe sections.... Austin utilized
in-place grouting and sewer repairs to reduce
infiltration and develop a program which reviewed
209,597 feet during 1966 to 1967.
097 SCOURED SEWERS AND TV INSPECTION
American City; p 118, February 1968
Descriptors: Maintenance, TV Inspection
Water jet cleaner flushes and scours pipe at 1000 ft.
per hour. Under normal use, it requires one gallon of
water per foot of pipe cleaned. ...in locating sources
of trouble such as cracked pipe, tree roots, incorrect
service taps, and lost service lines (a closed circuit TV
had been used.) A custom-built trailer houses the
entire TV system and provides... viewing... during
operations.
098 REMOTE CONTROL GROUTING OF SEWER
LINE LEAKS
J. Metz
Water and Wastes Engineering, vol 5, no 6; p 68, 1968
117
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Descriptors: Grouting
The Merriville Conservancy District used remote
control grouting... grouting packer was used to pump
grout into... leak.
099 MASSIVE SEWER INFILTRATION
T. E. Llewellyn
American City, vol 83, no 10; p 90, 1968
Descriptors: Investigations, Joints, Sealant
North Tahoe public utility districts (have) suffered
from surcharged sewers, manholes, and overloaded
pump stations. The district began a program to
combat excessive infiltration. An investigative phase
was followed by corrective action. Key West, Florida,
uses a sealant to control infiltration... introduced into
a sewer between adjacent plugged manholes.
100 BARGAIN REPAIRS WITH TV AND GROUT
D. Hurlbert
Public Works; pp 106-107, September 1968
Descriptors: Grouting, Joints, TV Inspection
Description of planning, inspection and grouting of
leaking sewer joints in Kansas City, Missouri.
101 ELIMINATING SEWER LEAKS - FROM THE
INSIDE AND OUTSIDE
C. P. Aguero
American City, October 1968
Descriptors: Economics, Grouting, Joints, Sealant
In two weeks, city crew eliminated ^ mgd. of
infiltration. Methods and costs are described.
102 WHAT JET SEWER CLEANERS DO TO
SEWER JOINTS
I. W. Santry, Jr.
American City, vol 83, no 11; pp 96-97, November
1968
Descriptors: Jet Cleaners, Joints, Maintenance
Tests conducted at Garland, Texas, Water Utilities
Department, to find out what strong jet action of
new machines using high pressure hydraulic jets does
to sewer joints as it passes through line; results
showed that there was no damage from jet spray if
line was properly constructed.
103 REPORT ON PLASTIC LINING OF OLD
SEWER PIPES IN TORONTO, ONTARIO
R. M. Bremner
Report to City Council, May 21,1969
Descriptors: Economics, Liners
Report outlining method and costs of placing plastic
liner in existing leaking sewers.
104 SEWERS FOR GROWING AMERICA
Dr. M. M. Cohn
Certainteed Products Corporation; 1966
Descriptors: Construction, Design, Economics,
Planning
Authoritative manual on history and development of
sewer systems in America. Contains sections on
planning, design, financing and construction of
sewers.
105 THE DETECTION AND SEALING OF LEAKS
IN SEWERS
B. W. Brunton
Canadian Municipal Utilities, vol 101, no 12, pp
22-23, December 1963
Descriptors: Economics of Correction, Grouting,
Sealant, TV Inspection
Discussion of dangers and costs of infiltration in
Sudbury, Ontario. Also reviews the Penetryn system
of TV inspection and grouting. Costs are given.
106 CUSTOM BUILT SEWER TV
Canadian Municipal Utilities, vol 103, no 2, pp 32-33,
February 1964
Descriptors: TV Inspection
Scarborough, Ontario has purchased its own custom
TV inspection equipment rather than rental
equipment. Costs are given.
118
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107 THE DEGRADATION OF NATURAL
RUBBER PIPE JOINT RINGS
D. A. Hills
Rubber Journal, vol 149, no 11, pp 12-13, 15, 17,
77 November 1967
Descriptors: Joints, Rubber Rings
Deterioration of rubber pipe joints due to bacterial
action. Research report.
108 OVERLAND FLOW AND GROUNDWATER
FLOW FROM A STEADY RAINFALL OF FINITE
DURATION
F. M. Henderson, R. A. Wooding
Journal of Geophysical Research, vol. 69, no 8, pp
1531-1540, April 15, 1964
Descriptors: Design, Groundwater, Rainfall, Runoff
Development of mathematical analysis of rainfall
effects on ground and surface water drainage.
109 OVERLOADING OF SEWERS: SOME
CORRECTIVE MEASURES AND
CONTEMPLATED IMPROVEMENTS
W. H. Bolton
Seventy-Fourth Annual Report, Connecticut Society
of Civil Engineers, pp 35-41, 1958
Descriptors: Combined Sewers, Joints, Repairs,
Sanitary Sewers, Storm Sewers
Review of experience in New Haven, Connecticut
with failures of storm and sanitary sewers due to
floods, infiltration and other overload conditions.
110 DEFECTIVE SEWER RELINING WITHOUT
EXCAVATION
The Surveyor, vol 123, no 3745, p 42, 1964
Descriptors: Gunite, Relining, Sewer Repair
Brief explanation of gunite and other techniques
developed by William F. Rees, Ltd., to repair and seal
old sewers in place. Work was performed in London,
England.
111 TRACING INFILTRATION IN SEWERS
J. Gaskin
The Surveyor, vol 109, no 3064, p 605, November
24,1950
Descriptors: Infiltration
Description of early methods to locate infiltration in
England.
112 HANDBOOK OF DRAINAGE AND
CONSTRUCTION PRODUCTS
Armco Drainage and Metal Products, Inc.
Middletown, Ohio
Descriptors: Design, Drainage, Steel Pipe
Valuable design and construction information for
storm and sanitary sewers. Many tables, graphs, charts
and references.
113 CONCRETE PIPE HANDBOOK
American Concrete Pipe Association
Arlington, Virginia
Descriptors: Design, Concrete Pipe
Authoritative information on design and construction
standards for concrete pipe.
114 REGULATIONS OF SEWER USE
Water Pollution Control Federation Manual No. 3
Washington, D.C.
Descriptors: Regulations
A review of regulatory ordinances and methods for
controlling sewer use.
115 SEWER MAINTENANCE
Water Pollution Control Federation, Manual No. 7
Washington, D.C.
Descriptors: Maintenance
Authoritative manual of recommended practice in the
field of sewer maintenance.
119
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116 REHABILITATION OF A CONCRETE SEWER
UNDER INFILTRATION PRESSURE
Harold H. Haugh
Public Works, vol 100, no 7, pp 89-90, July 1969
Descriptors: Concrete Pipe, Grouting
Description of repairs to concrete pipe sewer with a
special gunite process.
117 SEWERS NEED BETTER SOILS
ENGINEERING
Joseph S. Ward
American City, vol 84, no 7, pp 72-74
Descriptors: Construction, Design, Soils
Discussion of the role of the soils engineer in sewer
design and to insure better construction, to save
money and to simplify the work.
118 HANDBOOK OF CAST IRON PIPE
Cast Iron Pipe Association
Oak Brook, Illinois
Descriptors: Cast Iron Pipe
Design handbook for sewer and water systems with
cast iron pipe.
119 DALLAS HAS MODERN APPROACH TO
SEWER INSTALLATION
H. J. Graeser
Water and Sewage Works, vol 226, no 9, pp 326-331,
September 1969
Descriptors: Construction, Joints
A discussion of current materials, pipes, joints and
methods utilized to produce tight sewer system. An
analysis of future needs for development.
120 A PLASTIC SEWER LINER
R. M. Bremner
American City, vol. 84, no 9, pp 98-101, September
1969
Descriptors: Liners
The rehabilitation of small-diameter sewers at
two-thirds of the cost and one-third of the time
required for reconstruction.
121 LOW PRESSURE AIR TESTS FOR SEWER
LINES
W. J. Malcolm
American City, vol 84, no 11, pp 74-75, November
1969
Descriptors: Air-testing
A series of questions and answers on the subject of
low-pressure air testing.
122 WE KEPT THE SEWER IN SERVICE
Jack D. Foster and Jack W. Tooley
American City, vol 84, no 11, pp 97-99, November
1969
Descriptors: Liners
Description of use of a new reinforced plastic mortar
pipe, Techite, in a seriously corroded interceptor in
Oakland, California.
123 ABS TRUSS PIPE FOR SEWERS
T. L. Willhoff
Water and Wastes Engineering, vol 6, no 3, pp 40,42,
March 1969
Descriptors: Plastic Pipe, Truss Pipe
Description of ABS truss pipe which has been
developed for sewers. Results of tests are given.
124 SEWER PIPE SETTLEMENT STUDIES
Civil Engineering - ASCE, p 70, October 1965
Descriptors: Soils
125 EXFILTRATION TESTING OF LARGE
SEWERS IN KANSAS CITY, MISSOURI
Jerome F. Fladring and Lloyd W. Weller
Water and Wastes Engineering, pp 87-89, September
1967
Descriptors: Exfiltration, Tests
120
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Description of methods for testing sewers in Kansas
City.
126 INFILTRATION IN SANITARY SEWERS
I. W. Santry, Jr.
Water Pollution Control Federation, Journal, pp
1256-1261, October 1964
Descriptors: Infiltration
General discussion of infiltration problem in sanitary
sewers.
127 PRACTICAL METHODS FOR DETERMINING
SEWAGE FLOW FOR ALL COMMUNITIES
R. M. Girling
Water and Sewage Works, pp 250-258, July 1969
Descriptors: Flow Measurements
Review of methods used for measuring sewage flow.
128 MODERN SEWAGE TREATMENT PLANTS -
HOW MUCH DO THEY COST?
U. S. Public Health Service
Division of Water Supply and Pollution Control, 1964
Descriptors: Economics
...guidelines derived from the PHS data reflects the
varying costs of sewage treatment plant construction
as influenced by size of plant, type of treatment,
...and other factors. The answers provide a
dependable base for future financing practices....
129 ESTIMATING SEWAGE TREATMENT PLANT
OPERATION AND MAINTENANCE COSTS
P. P. Rowan, K. L. Jenkins, D. H. Howells
Journal of the Water Pollution Control Federation,
vol 33; February, 1961
Descriptors: Economics
The report is based on a PHS survey of municipal
treatment plants throughout the United States. The
data are summarized by type of treatment and size of
plant of primary and secondary treatment systems.
130 THE ECONOMICS OF URBAN SEWAGE
DISPOSAL
Paul B. Downing
Frederick A. Praeger, Publishers; New York, 1969
Descriptors: Economics
The report examines the various costs of collection
and treatment, optional system sizes, water quality
standards and the financing of urban sewage facilities.
131 LOW PRESSURE AIR TESTING OF SEWERS
William J. Chase, Harvey W.
Pacific Northwest Pollution Control Association
Meeting, Vancouver, Washington, November 5, 1965
Descriptors: Air Testing
The report includes review of the test development,
discussions of experiences, recommended
specifications, and equipment sketches.
132 PLASTIC LINER REPAIRS LEAKING SEWER
Lyle D. Johnson
Public Works, June 1970, pp 85-86
Descriptors: Repairs
A 54 in. outfall was sealed by using a 26 oz per sq yd
PVC sheet sandwich reinforced with Polyester fabric.
133 BOCA BASIC PLUMBING CODE, 1970
Building Officials and Code Administrators
International, Inc., Chicago, Illinois
Descriptors: Plumbing
A model code
134 SOUTHERN STANDARD PLUMBING CODE,
1967
Southern Building Code Congress, Birmingham,
Alabama
Descriptors: Plumbing
A model code
135 UNIFORM PLUMBING CODE
International Association of Plumbing and
Mechanical Officials, Los Angeles, California
Descriptors: Plumbing
A model code
121
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r
BIBLIOGRAPHIC: American Public Works Association
Research Foundation, Control of Infiltration and Inflow Into
Sewer Systems. FWQA Publication No. 11022 EFF 12/70
ABSTRACT: Two hundred and twelve public jurisdictions in
the United States and Canada were contacted, and twenty-six
communities were visited. Practices of consulting engineers
and state and provincial water pollution control agencies were
also surveyed.
The surveys indicated that infiltration and inflow are
widespread problems.
Reduction of infiltration should be stressed in both new and
old systems. For new sewers a construction allowance of no
more than 200 gallons per day per inch of diameter per mile
of pipe is recommended. Existing systems must be extensively
investigated to determine the extent and location of
infiltration. Reduction of inflow waters can be accomplished
after sources of sucR flows have been identified, alternate
methods of disposal identified, and the backing of public and
governing bodies secured.
(Continued)
KEY WORDS
Infiltration
Inflow
Investigations
Inspection
Survey
BIBLIOGRAPHIC: American Public Works Association
Research Foundation, Control of Infiltration and Inflow Into
Sewer Systems. FWQA Publication No. 11022 EFF 12/70
ABSTRACT: Two hundred and twelve public jurisdictions in
the United States and Canada were contacted, and twenty-six
communities were visited. Practices of consulting engineers
and state and provincial water pollution control agencies were
also surveyed.
The surveys indicated that infiltration and inflow are
widespread problems.
Reduction of infiltration should be stressed in both new and
old systems. For new sewers a construction allowance of no
more than 200 gallons per day per inch of diameter per mile
of pipe is recommended. Existing systems must be extensively
investigated to determine the extent and location of
infiltration. Reduction of inflow waters can be accomplished
after sources of such flows have been identified, alternate
methods of disposal identified, and the backing of public and
governing bodies secured.
(Continued)
f—
KEY WORDS
Infiltration
Inflow
Investigations
Inspection
Survey
BIBLIOGRAPHIC: American Public Works Association
Research Foundation, Control of Infiltration and Inflow Into
Sewer Systems. FWOA Publication No. 11022 EFF 12/70
ABSTRACT: Two hundred and twelve public jurisdictions in
the United States and Canada were contacted, and twenty-six
communities were visited. Practices of consulting engineers
and state and provincial water pollution control agencies were
also surveyed.
The surveys indicated that infiltration and inflow are
widespread problems.
Reduction of infiltration should be stressed in both new and
old systems. For new sewers a construction allowance of no
more than 200 gallons per day per inch of diameter per mile
of pipe is recommended. Existing systems must be extensively
investigated to determine the extent and location of
infiltration. Reduction of inflow waters can be accomplished
after sources of such flows have been identified, alternate
methods of disposal identified, and the backing of public and
governing bodies secured.
KEYWORDS
Infiltration
Inflow
Investigations
Inspection
Survey
I
(Continued)
-------
Twenty recommendations are given indicating the need for )
extensive investigation of the extent of the infiltration/inflow
problem before relief sewers are constructed or wastewater I
treatment plants built or enlarged.
The report includes 43 tables, an extensive review of reports I
concerning local infiltration studies, and a bibliography of .
135 references. I
This report was prepared for the Environmental Protection j
Agency in fulfillment of Contract 14-12-550. The study was '
also supported by thirty-nine public agencies. A companion I
document, "Manual of Practice, Prevention and Correction of
Excessive Infiltration and Inflow into Sewer Systems," was I
also prepared.
Twenty recommendations are given indicating the need for I
extensive investigation of the extent of the infiltration/inflow :
problem before relief sewers are constructed or wastewater I
treatment plants built or enlarged.
The report includes 43 tables, an extensive review of reports |
concerning local infiltration studies, and a bibliography of ,
135 references. .
This report was prepared for the Environmental Protection I
Agency in fulfillment of Contract 14-12-550. The study was ,
also supported by thirty-nine public agencies. A companion '
document, "Manual of Practice, Prevention and Correction of |
Excessive Infiltration and Inflow into Sewer Systems," was
also prepared. I
Twenty recommendations are given indicating the need for
extensive investigation of the extent of the infiltration/inflow
problem before relief sewers are constructed or wastewater
treatment plants built or enlarged.
The report includes 43 tables, an extensive review of reports
concerning local infiltration studies, and a bibliography of
135 references.
This report was prepared for the Environmental Protection
Agency in fulfillment of Contract 14-12-550. The study was
also supported by thirty-nine public agencies. A companion
document, "Manual of Practice, Prevention and Correction of
Excessive Infiltration and Inflow into Sewer Systems," was
also prepared.
-------
1
Accession Number
w
5
2
Subject Field &. Group
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
Organization
The American Public Works Association, Chicago, Illinois 60637
Title
CONTROL OF INFILTRATION AND INFLOW INTO SEWER SYSTEMS
1 Q Author(s)
American Public Works Association
16
21
Project Designation
Program No. 11022
err l£//U{ArVvA — bo-laj
Note
22
Citation
23
Descriptors (Starred First)
Infiltration? I nf low ."investigations* Inspection, Survey
25
Identifiers (Starred First)
Construction allowance
27
Abstract
ABSTRACT
Two hundred and twelve public jurisdictions in the United States and Canada were contacted, and twenty-six
communities were visited. Practices of consulting engineers and state and provincial water pollution control agencies
were also surveyed.
The surveys indicated that infiltration and inflow are widespread problems.
Reduction of infiltration should be stressed in both new and old systems. For new sewers a construction
allowance of no more than 200 gallons per day per inch of diameter per mile of pipe is recommended. Existing
systems must be extensively investigated to determine the extent and location of infiltration. Reduction of inflow
waters can be accomplished after sources of such flows have been identified, alternate methods of disposal
identified, and the backing of public and governing bodies secured.
Twenty recommendations are given indicating the need for extensive investigation of the extent of the
infiltration/inflow problem before relief sewers are constructed or wastewater treatment plants built or enlarged.
The report includes 43 tables, an extensive review of reports concerning local infiltration studies, and a
bibliography of 135 references.
This report was prepared for the Environmental Protection Agency in fulfillment of Contract 14-12-550. The
study was also supported by thirty-nine public agencies. A companion document, "Manual of Practice, Prevention
and Correction of Excessive Infiltration and Inflow into Sewer Systems," was also prepared.
Abstractor
Richard H. Sullivan
Insti tution
APWA Research Foundation
WR;102 (REV. JULY 1969)
WRSI C
SEND, WITH COPY OF DOCUMENT, TO: WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D.C. 20240
ft GPO: 1970-369-930
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Continued from inside front cover....
11022 — 08/67
11023 --- 09/67
11020 — 12/67
11023 —- 05/68
11031 — 08/68
11030 DNS 01/69
11020 DIM 06/69
11020 DES 06/69
11020 —- 06/69
11020 EXV 07/69
11020
11023
11020
11020
11020
11024
11020
11000
DIG 08/69
DPI 08/69
DGZ 10/69
EKO 10/69
— 10/69
FKN 11/69
DWF 12/69
— 01/70
11020 FKI 01/70
11024
11023
11024
11023
11024
DDK 02/70
FDD 03/70
CMS 05/70
EVO 06/70
— 06/70
Phase I - Feasibility of a Periodic Flushing System
for Combined Sewer Cleaning
Demonstrate Feasibility of the Use of Ultrasonic
Filtration in Treating the Overflows from Combined
and/or Storm Sewers
Problems of Combined Sewer Facilities and Overflows,
1967, (WP-20-11)
Feasibility of a Stabilization-Retention Basin in Lake
Erie at Cleveland, Ohio
The Beneficial Use of Storm Water
Water Pollution Aspects of Urban Runoff, (WP-20-15)
Improved Sealants for Infiltration Control, (WP-20-18)
Selected Urban Storm Water Runoff Abstracts, (WP-20-21)
Sewer Infiltration Reduction by Zone Pumping, (DAST-9)
Strainer/Filter Treatment of Combined Sewer Overflows,
(UP-20-16)
Polymers for Sewer Flow Control, (WP-20-22)
Rapid-Flow Filter for Sewer Overflows
Design of a Combined Sewer Fluidic Regulator, (DAST-13)
Combined Sewer Separation Using Pressure Sewers, (CRD-4)
Crazed Resin Filtration of Combined Sewer Overflows, (DAST-4)
Storm Pollution and Abatement from Combined Sev/er Overflows-
Bucyrus, Ohio, (DAST-32)
Control of Pollution by Underwater Storage
Storm and Combined Sewer Demonstration Projects -
January 1970
Dissolved Air Flotation Treatment of Combined Sewer
Overflows, (WP-20-17)
Proposed Combined Sewer Control by Electrode Potential
Rotary Vibratory Fine Screening of Combined Sewer
Overflows, (DAST-5)
Engineering Investigation of Sewer Overflow Problem -
Roanoke, Virginia
Microstraining and Disinfection of Combined Sewer
Overflows
Combined Sewer Overflow Abatement Technology
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