WC138 SeptOct 2024 - Flipbook - Page 20
INFRASTRUCTURE
Table 1. Summary of data collected from 13 water utilities (green – data collected, black – data not collected)
Total length
of pipes
(km)
Length of
broken pipes
(km)
Break decades
available
Length
Material
Diameter
Joint type
Install
year
Failure
year
Failure
Month
Failure
Type
Failure
Cause
Lining
material
Soil type
A
897
61
1970-2020
B
6,811
1,048
1950-2020
C
3,183
440
1970-2020
D
2,710
384
1970-2020
E
1,084
145
1980-2020
F
1,501
147
1970-2020
G
392
18
1980-2020
H
1,363
238
1950-2020
I
694
96
1980-2020
J
1,577
29
2000-2020
K
351
74
1980-2020
L
481
53
2000-2020
M
4,862
576
1950-2020
other types of factors, such as joint type,
and pipe protection type remain to be
studied. Considering all these factors,
what can we expect in each season, and
at each stage, of the pipe’s lifecycle?
Figure 1. Watermain breaks by month and seasonal trends
15%
A Canada-wide study
10%
To answer this question, a comprehensive study was conducted at the
5%
University of Concordia using data
collected from 13 Canadian cities in the
0%
provinces of Alberta, British Columbia,
JAN
FEB
Manitoba, Nova Scotia, Newfoundland
and Labrador, Ontario, and Saskatchewan. This data encompasses nearly
26,000 kilometres of pipes and more than 62,000 recorded
watermain failures, as detailed in the table below. Diameter, material, length, installation year, and failure year were consistently
collected by all utilities. Other, less frequently collected factors
included joint type, soil type, and lining material. By analyzing
this extensive dataset through correlation and chi-squared analyses, we uncovered patterns and relationships between pipe break
characteristics and system properties. This helped us understand
how different factors interact and influence watermain failures,
providing insights that inform improved design, maintenance,
and rehabilitation strategies.
The results from this comprehensive study showed the interconnection of these factors in the occurrence of breaks. These
findings and their implications are summarized in the following
paragraphs.
20
PERCENT OF BROKEN PIPES
20%
WATER C AN ADA • SEP TEMBER/OCTOBER 2024
PEAK SUMMER • HEAT
Coal tar lined pipes crack
WINTER • FREEZE/THAW
Small diameter pipes have
circumferential breaks
FALL • WET
Pipes with
collar joints break
SUMMER • CONSTRUCTION
More accidental breaks
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
Seasonality
The study revealed significant seasonal trends related to watermain
failures, as summarized in the figure below. While seasons are
known to impact failure rates, often depending on material and
soil, this study found additional insights into the impacts of joint
type, lining type, and failure type. During the winter months,
small diameter pipes are more likely to experience circumferential breaks due to temperature changes and freeze-thaw cycles. In
contrast, the summer months show a higher incidence of failures
in medium to large diameter pipes, particularly asbestos cement
(AC) pipes. These failures are often due to accidents, likely caused
by increased construction activity next to the pipes. The peak of
summer, particularly in July, sees an increased failure rate in coal
tar-lined pipes, which are prone to cracking under high temperatures. As the season transitions from summer to early fall, pipes
WAT E R C A N A D A . N E T
