Not All Failing Pipelines Are Old

Engineer error, poor construction also at issue in many cases

ONE hundred-year-old cast iron pipe is still working well in such cities as Seattle, Wash., and Portland, Ore., because of prudent asset management. Much younger prestressed concrete cylinder pipe (PCCP) has been falling apart at alarming rates in Tucson, Ariz., and numerous other cities coast to coast.

The United States has more than 8 million miles of pipeline. More than 40,000 major sewage spills and over 300,000 major water main breaks were reported last year. Media accounts often say that America's water distribution and wastewater collection systems are worn out, but some of the problems associated with pipelines have more to do with human error than age.

The following examples will help illustrate this point:

California
On November 9, 2004, a fireball resulted when a backhoe operator hit the jet fuel line next to the trench in which an 89-inch water pipe was being constructed for the East Bay Municipal Utility District. Workers died and others suffered severe burns. This incident resulted in an investigation and citations from the California Department of Industrial Relations' Division of Occupational Safety and Health Administration (Cal/OSHA). The state government said the explosion was "completely preventable." Apparently, utility mapping was poorly done.

Texas
When the PCCP in a major regional water district began to explode in Texas, the desperate owner turned to the pipe supplier and the design engineering firm for help. Both of them attributed the problem to the way the bends were designed.

The water utility hired an independent consultant, who found the pipe to be deficient in meeting design standards and specifications and bedding and backfilling specifications. The consultant reported that the failures were due to the use of flooding to place the bedding in highly expansive soils—a recommendation from the design engineering firm.

To date, millions of dollars have been spent on better design of the bends, long-term field monitoring to keep counting the prestressing wires that are likely to break, and the construction of risk curves.

The problems with pipelines expand beyond water and wastewater systems to include other infrastructure that helps to direct water where it needs to go.

NOT ALL PIPES ARE FOR WATER
How big is the U.S. pipeline infrastructure: How many miles and what kinds of pipelines are there?
In 2003, there were more than 2.3 million miles of pipeline in the United States carrying natural gas, and hazardous liquids (chiefly petroleum and refined petroleum products, as well as chemicals and hydrogen). Here is a breakdown:

Type of pipeline                        Mileage           Total
Hazardous liquid (2003)           160,868           160,868

Natural gas transmission
Gathering Lines                         19,864
Transmission Lines                    278,269
Total                                                                  298,133

Natural gas
Distribution mains                      1,119,430
Distribution service lines             729,550
Total                                                                 1,848,980
Grand Total                                                       2,307,981
Source: U.S. Department of Transportation Pipeline & Hazardous Materials Safety Administration.

Massachusetts
Boston's Big Dig, which has required continuous pumping of more than 2 million gallons of water during the project, now has been scrutinized by the government. The roof of a tunnel collapsed last year, killing a woman on her way to Logan Airport. The National Transportation Safety Board has indicated the problem involved the use of epoxy glue that held ceiling panel bolts in place, according to the San Francisco Chronicle (July 11, 2007). According to the Boston Globe (July 14, 2007), officials have demanded "Bechtel-Parsons Brinckerhoff [the group that contracted to manage design and construction of the project ] pay as much as $1 billion to settle claims for shoddy work in exchange for a guarantee that the consortium would not face criminal charges, according to four sources with knowledge of the negotiations."

The fact that the government may pursue action against the consortium further illustrates how serious the problems in engineering can become.

Similar to problems in other professions, engineering has its share of insufficiently qualified individuals who don't know geotechnical or pipeline engineering, but they still perform work with underground pipeline projects. Often pipe vendors, who are good salespeople but lack adequate engineering background, bring the technical know-how to these complex projects. However, they also bring an obvious conflict of interest and don't always consider all the technical aspects of a job.

The problem of pipeline failures seems to stem from a knowledge gap. Universities do not offer formal classes and training in underground pipeline design, construction, and management. Many design engineers do not understand pipesoil interaction principles. Because pipes can be made from different materials, their behavior can be different under varying circumstances. All of these things can be learned.

Good engineering practices are not always being used. During design or construction of a pipeline, engineers must use appropriate and adequate utility mapping. Licensed engineers should supervise proper pipe design and manufacture at the factory and on-site. And, of course, proper operation and maintenance and useful life of the pipeline must be taken into account.

Other, not so obvious contributing factors to pipeline failure include:

• Claims and counterclaims of pipe manufacturers. For example, a steel pipe maker may tell prospective buyers of ductile iron pipe that they shouldn't believe that a poly wrap bag will protect that pipe from corrosion. In the meantime, the ductile iron pipe association may issue a report showing that a poly wrap bag does work, and they provide proof from 12 different sites around the country. Who is the buyer to believe?

• Inconsistent design standards, sometimes by the same governing body, for different pipe materials, and

• Political pressure brought on the engineer by pipe interest groups. When an experimental pipe is forced on the engineer of record by the pipe supplier, who has been golfing with the city council member, this is an example of political pressure leading to a possible pipe failure. When each pipe material supplier forces the engineer to lower the requirements by bringing pressure from those who hold office in the city government, this can lead to failures, and it has in some cases.

While there is a dramatic increase in volume of pipeline work, there is an obvious severe shortage nationwide for engineers with sufficient experience in underground pipeline design, construction, and management. Universities need to offer classes in underground pipelines as part of their curriculum. Engineering firms need to be held more accountable by the public and regulatory agencies to prevent them from continuing to take underground pipeline projects and performing work outside their core competencies. Contractors need to be pre-qualified based on their track record of having completed high-quality pipeline projects without incidents.

This article originally appeared in the 09/01/2007 issue of Environmental Protection.

comments powered by Disqus