Something Fishy Appears To Be Going On At Tucson Water
By Paula Huff
THE CITY OF Phoenix Water Services Department has officially banned the use of PVC pipe in the construction of water mains, citing concerns regarding its durability in hot weather.
Tucson suffers under the same heat as Phoenix, yet PVC is the material of choice for Tucson Water's ongoing efforts to replace old and crumbling water mains.
So what's going on here?
According to John Nachbar, deputy city manager and acting director of Tucson Water, "engineers" decided PVC would be the best type of pipe to use in the water main replacement program--despite the fact, as Nachbar himself has noted, that other Arizona cities have placed a moratorium on further PVC use.
Which engineers in particular made the decision? Apparently nobody at Tucson Water could come up with the names. After a reporter asked this question several times of various Tucson Water officials, Gwen Goodman, one of the main-replacement project's managers, said the utility made the decision to use PVC back in 1986, when Frank Brooks was Tucson Water's director. (Brooks has since retired.)
Nachbar noted that ductile iron pipe, the rugged grandaddy of urban water delivery vehicles, costs about 125 percent more to install than PVC.
But according to Tucson City Councilman Steve Leal, the major expense in replacing water mains is the cost of digging up the street, which, of course, must be done no matter what type of pipe is being used.
Kevin Heberle, another main-replacement project manager, says ease of installation is a big reason Tucson Water chose to use to use PVC, which snaps together like Tinkertoys. Meanwhile, the City of Phoenix has switched to polyethylene in its water system. Polyethylene piping comes in 20-foot rolls and requires above-ground welding with a hot plate.
According to a private study conducted for the City of Phoenix, the smallest dimension ratio (DR) of PVC pipe must be no greater than 11 for service in such a high-temperature area. The smaller the DR, the thicker the walls of the pipe. Currently, the smallest DR available for water mains is 14, and Nachbar says DR 14 PVC is being used in Tucson's main replacement project.
However, according to project manager Heberle, thinner-walled DR 18 PVC is being used in some areas, although he would not specify where.
Recent technical literature from Lasco Fluid Distribution Products--which sells PVC, but is not one of the City of Tucson's allowed PVC sources--states:
PVC being a thermoplastic means it is softer when it is heated and when operating above 73 degrees Fahrenheit, both static and surge life is reduced as well as the stiffness.
Of course, Tucson Water is not about to buy PVC from a manufacturer who readily admits that anything over 73 degrees Fahrenheit may cause problems, especially when Nachbar himself says the soil temperature 44 inches under asphalt, where the mains generally are buried, reaches 90 degrees Fahrenheit in the summer, a figure confirmed by Paul Brown, of the UA Soils Chemistry Department. Heberle confirms the mains will be buried between 36 inches and 44 inches deep. And his supervisor, Steve Pageau, confirms most will be buried under asphalt.
Another factor affecting the durability of PVC is the static pressure rating of the pipe. Water mains are under forced pressure. Lasco's literature states that surges due to some golf course installations exceed the static pressure rating of the pipe and can occur hundreds of times daily. In this situation, the service life of the PVC pipe leading into the golf courses, along with the water lines within the courses, may be greatly shortened. PVC pipes in one particular golf course studied were "reduced to a range of two to five years," according to Lasco.
Seven golf courses are in development in and around Marana, according to Joel Shapiro, principal planner of the Town of Marana.
Common sense suggests that the high operating temperature of Tucson's water system, combined with pressure surges due to increasing numbers of golf courses in the area, could mean many new PVC water mains may blow apart within a few years.
Pageau also notes the people who live in Tucson-area foothills have the most to worry about with the new PVC mains, because it takes a lot of pressure to propel water uphill.
THIS TROUBLING SITUATION is further complicated by the fact that, according to Heberle, Tucson Water is replacing only galvanized steel mains, even though some of the city's ductile iron water mains have been in place for 50 to 70 years. And, according to the official description which appeared on Tucson's 1994 bond ballot, some of these mains have been in place for 100 years.
Of course the reason Tucson Water is replacing the relatively recent galvanized steel pipes is because they reacted badly with CAP water a few years back.
Tucson Water's solution to the problem was to add anti-corrosives to the water. But Tucson citizens who received this stuff apparently didn't want to be drinking what amounted to Rustoleum, so they passed Proposition 200, the Clean Water Initiative, which forbids Tucson Water from running that nasty CAP crap into our homes.
A move is currently afoot, in the form of Proposition 201 on the upcoming November ballot, to repeal the Clean Water Initiative. This latest proposition is bankrolled chiefly by a developer, a pool builder and businessman Joe Cesar, who stands to profit handsomely if CAP is delivered to local homes, because Cesar owns land near what would become a large, artificial lake to be used as a CAP water storage facility.
Furthermore, according to Tucson Water's own documents, released by Pageau, no more than 70 mg/L of total dissolved solids should be in the water run through PVC, or damage to the pipes may result. But according to other Tucson Water documents released by the utility's public information office, Tucson's groundwater has 280 mg/L of total dissolved solids, while CAP water has a whopping 650 mg/L.
Another fact revealed in the documents: At 90 degrees Fahrenheit, the pressure capacity of DR 18 PVC is only 114 psi. According to Heberle, Tucson Water's system has an operating pressure of 80 psi, with occasional surges to 150 psi.
And finally, Tucson Water did not conduct any scientific research before deciding to use PVC, according to Goodman, who says utility officials apparently relied on a 1980 report by the American Water Works Association, which she claims is reliable. The report did not include studies of areas as hot as Tucson.
When a reporter recently attempted to ask Nachbar a few questions regarding the use of PVC in the water-main replacement project, her first several phone calls to Tucson Water proved fruitless. Finally, she called the city manager's office, which gave her Nachbar's e-mail address, email@example.com.
The reporter sent her questions via computer. A week passed, then two weeks, then three. Finally, after Councilman Steve Leal apparently advised him it would be a good idea to talk to the press, Nachbar sent the reporter a memo answering only about half her questions.
And the big question still remains unanswered: Why is Tucson Water so concerned about replacing water mains simply because they react badly with CAP water? And, more importantly, how will the voters who approved the Clean Water Initiative react to the fact that something fishy is going on here?
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