2012 Trenchless Technology Water Main Survey Results

There are more than 1 million miles of water mains in North America today, providing residential and commercial users with the water they need each day. Many pipes are well over 100 years old — still going strong but are in need of maintenance and in some cases an upgrade. The public doesn’t seem to pay attention to how their water travels to their faucets until there is a breakage or leak and then everyone’s interested in new pipes and most of all the cost.

Although water mains do last a long time, much of the pipe installed over the last century is reaching or has reached the end of its lifespan and will need replaced and/or rehabilitated now and in the coming years. Evidence of this need is in this statement: Every day 850 water main breaks occur in North America at a total annual repair cost that exceeds $3 billion, according the website watermainbreakclock.com. The website further notes that corrosion is the leading cause of water main breaks, resulting in a significant drag on the economy.

Trenchless Technology wanted to know what type of pipe municipalities around North America are using as their vessels to transport their drinking water to customers and what methods they are using to replace and/or maintain their existing and aging systems. We also wanted to know how they are collecting data and what their biggest concerns are.

We conducted an informal water main survey of water system operators and consulting engineers from across North America to assist in gauging our water mains. Below are the results of this non-scientific poll. One thing our poll shows is that although trenchless technology is part of the equation when it comes to addressing water main issues, it still has some inroads to make to gain municipal acceptance.

(Editor’s Note: For some questions, respondents were allowed to check more than one answer, making some of the percentages exceed 100 percent.)

Sharon M. Bueno is managing editor of Trenchless Technology.

1. Rate the overall condition of your water mains:

Very poor    2.5 percent
Poor    11.25 percent
Average    60 percent
Above average    22.5 percent
Like new    3.75 percent

2. Rate the importance of the following characteristics when choosing pipe material:

The longevity and design life was the most important factor in choosing pipe, with 87 percent of respondents indicating that this was “extremely important.”  The second most important criterion was meeting standards at 82 percent. Price and ease of installation had the least amount of“extremely important” responses at 25 and 28 percent, respectively;although 64 percent and 72 percent of respondents, respectively,indicated that these were “important.” Regarding compatibility with an existing systems, 53 percent of respondents said this was “extremely important.”

3. What types of data do you use to determine the need for replacement/repair?

Break history was the most popular response to this question with 88percent of respondents choosing it, with a age of pipe a close second at79 percent. Leak detection had 50 percent of respondents selecting it and 9 percent of respondents use CCTV to determine the need for replacement/repair. Nine percent use other methods such as radio frequency testing, their asset management program and loss of capacity.

4. On average, how many water mains break per mile, per year do you experience?

For this question, the responses varied widely but on average,respondents suffered one water main break for every three miles of main.

5. What are the most common problems that your water mains experience?

The overwhelming response to this question was breakage at 80 percent,followed by leaks at 62 percent and corrosion at 43 percent. Finishing fourth was water quality (24 percent) and longevity (9 percent).

Breaks    80 percent
Leaks    62 percent
Corrosion    43 percent
Water Quality    24 percent
Longevity    9 percent
Other    5 percent

6. What type of pipe do you have in your water main system? Check all the apply

Ductile iron pipe (96 percent) outdistanced PVC and cast iron pipe (both76 percent). Asbestos cement finished third at 60 percent and HDPE fourth with 54 percent. Copper and galvanized iron were noted from those who chose “other.”

Ductile Iron    96 percent
PVC    76 percent
Cast iron    76 percent
Asbestos cement    60 percent
HDPE    54 percent
Steel    37 percent
Concrete    28 percent
PCCP    15 percent
Other    6 percent
Fiberglass    1 percent

7. What is your typical design life requirement?

The average design life requirement our respondents noted was 64 years.Most of the responses seem to be in the 50- to 100-year range.

8. What pipe materials are accepted?

Eighty-three percent of respondents say that ductile iron pipe is accepted, followed by PVC (64 percent) and HDPE (61 percent). No one chose asbestos cement or fiberglass pipe.

Ductile Iron    83 percent
PVC    64 percent
HDPE    61 percent
Concrete    19 percent
PCCP    13 percent
Steel    13 percent
Cast Iron    9 percent
Asbestos cement    0 percent
Fiberglass    0 percent

9. In your design spec, do you specify pipe material?

Yes    95 percent
No    5 percent

10. If yes, which pipe materials are specified?

When “type of pipe materials” is noted in the design specs, 82 percent of respondents said ductile iron is requested, outdistancing the second most popular choice, PVC (59 percent). HDPE came in third at 43 percent.

Ductile Iron    82 percent
PVC    59 percent
HDPE    43 percent
Concrete    16 percent
PCCP    11 percent
Steel    7 percent
Cast Iron    5 percent
Fiberglass    0 percent

11. What type of pipe is the easiest to maintain/rehab?

Here, PVC came out on top, with 52 percent of respondents saying it is the easy pipe to maintain/rehab, followed by ductile iron pipe at 49percent.

PVC    52 percent
Ductile Iron    49 percent
HDPE    13 percent
Cast Iron    7 percent
Concrete    3 percent
Steel    1 percent
Other    1 percent
Fiberglass    0 percent
PCCP    0 percent

12. What type of pipe is the most difficult to maintain/rehab?

For this question, there wasn’t one overwhelming choice. Cast iron pipe(33 percent) and concrete (23 percent) were the top two choices. Ductile iron was a close third with 19 percent. The pipe noted by those who selected “other” was asbestos cement.

Cast Iron    33 percent
Concrete    23 percent
Ductile Iron    19 percent
Steel    12 percent
Other    12 percent
PCCP    11 percent
HDPE    10 percent
PVC    7 percent
Fiberglass    5 percent

13. What percentage of your water mains do you rehab and replace each year?

According to our respondents, they average 4.3 percent in rehabbing and replacing their water mains each year.

14. What type of pipe achieves the longest life cycle?

Respondents chose basically two types of pipe as the ones they believe have the longest life cycle, cast iron (43 percent) and PVC (37percent). HDPE came in a distance third at 17 percent. Those who chose“other” noted ductile iron pipe.

Cast Iron    43 percent
PVC    37 percent
HDPE    17 percent
Other    6 percent
Steel    3 percent
Concrete    4 percent
Fiberglass    1 percent
PCCP    1 percent

15. Do you use trenchless technology methods to replace/rehab your water mains?

Yes    62 percent
No    38 percent

16. What methods do you use to replace/rehab your small diameter (up to 12 in.) water mains?

Conventional excavation remains the most-used method of replacing/rehabbing small diameter water mains (84 percent). Horizontal directional drilling was the most popular trenchless method at 38percent, with pipe bursting and boring at 16 and 25 percent,respectively. All trenchless methods received some responses in our poll, except for pilot-tube microtunneling.

Conventional Excavation    84 percent
Horizontal Directional Drilling (HDD)    38 percent
Pipe Bursting    26 percent
Boring    25 percent
Cured-in-place pipe (CIPP)    17 percent
Sliplining    11 percent
Fold-and-Form    5 percent
Cement Mortar Lining    8 percent
Epoxy Lining    7 percent
Pilot-Tube Microtunneling    0 percent

17. What methods do you use to replace/rehab your large diameter (14 in. and larger) water mains?

Are the result any different for the larger diameter water mains? Not much, other than an even wider gap between conventional excavation (89percent) and horizontal directional drilling (19 percent). There are even lower percentages of use for the remaining trenchless methods.

Conventional Excavation    89 percent
Horizontal Directional
Drilling (HDD)    19 percent
Cured-in-place pipe (CIPP)    14 percent
Sliplining    11 percent
Boring    12 percent
Pipe Bursting    8 percent
Cement Mortar Lining    8 percent
Epoxy Lining    8 percent
Fold-and-Form    3 percent
Other    3 percent
Pilot-Tube Microtunneling    0 percent

18. When performing trenchless applications, do you specify pipe materials?

Yes    84 percent
No    16 percent

19. What types of pipe do you use for trenchless projects?

Respondents to this question say they use HDPE (66 percent) and PVC (42percent) for their trenchless projects. Ductile iron pipe came in third with 23 percent.

HDPE    66 percent
PVC    42 percent
Ductile Iron    23 percent
Ductile Iron    23 percent
Other    12 percent
Concrete    5 percent
Steel    3 percent
PCCP    0 percent

20. Rate the importance of the following characteristics when selecting pipe material for a trenchless project

Respondents most often selected meets standards (80 percent) and longevity/design life (73 percent) as the most important characteristics in a pipe material. These were followed by compatibility with existing systems (62 percent) and ease to maintain/rehab and life cycle cost (both at 54 percent).

Compatibility with existing systems    62%    37%    1%
Ease of installation    49%    51%    9%
East to Maintain and Rehab    54%    35%    11%
Initial installation cost    46%    53%    1%
Life cycle of cost    54%    40%    6%
Longevity/design life    73%    23%    4%
Meets standards    80%    19%    1%
Price    49%    51%    0%

21. Does the type of pipe material required for a trenchless installation limit the use of trenchless techniques in your system

Yes    39 percent
No    61 percent

22. What is the biggest problem you face with pipe when completing trenchless installations?

Respondents noted that the biggest problems they face with trenchless installations are the connections (52 percent) and expense (43 percent),outdistancing the next highest percent that being compatibility issues with existing system (20 percent) and “other,” which noted local contractors and the culture of open-cut.

Connections    52 percent
Expense    43 percent
Compatibility issues with existing system    20 percent
Other     14 percent
Pipe availability    9 percent
Pipe doesn’t meet local codes    9 percent
Longevity    3 percent
Performance    3 percent
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