The forces of chemistry and physics became clear during 1992 inspections of half the city's concrete sewer pipe. Rather than fix the pipes, the city monitored, lowering cameras into sewers and waiting until 1998 to survey the whole network. The idea was to wait as long as possible before replacing or lining the pipes, a task that would cost well over $100 million. The city was betting that it could detect imminent disaster on a case-by-case basis and fix the deteriorating pipes over time. The stakes were huge, considering many of the pipes crossed freeways and rail lines that could be shut down if the pipes failed.
But the most recent surveys showed corrosion was an exponential equation. Even as the sinkhole on Lower Buckeye opened up, videotapes of the city's lines were showing that pipes that had looked okay five years earlier needed immediate replacement.
In a paper presented last year to the American Society of Civil Engineers, Paul Kinshella, a city wastewater engineer, and Ronald L. Ablin, a consulting engineer who helped assess the condition of the city's concrete pipes, wrote that all of the city's concrete pipe would be fixed over the next three years at a cost of $140 million. The city has already spent more than $150 million, but won't replace all of the suspect pipe. About five miles deemed good enough for at least five more years will remain in the ground. Once again, the city will monitor, gambling that the pipes won't crumble before they can be repaired.
Meanwhile, there are more critical emergencies elsewhere. And those crises can't wait.
Fixing just a tiny fraction of a sewer system costs tens of millions of dollars. Water officials boast that Phoenix has among the lowest sewer rates in the nation, but that's not necessarily a good thing, because city officials also admit they're short on money.
"Unfortunately, current estimates of wastewater revenues are not sufficient to meet all these expanded needs," reads a water-department report delivered to the City Council in December. "Less critical system rehabilitation and preventative maintenance projects will have to be delayed in order to address critical rehabilitation needs. This may create higher maintenance costs in the future; generate increased odor and service complaints; and risk system failures in some areas, which may be subject to regulatory enforcement."
Translation: The city doesn't have the money to fix its sewers, it doesn't have the political will to hike sewer rates enough to get the money, and policymakers are willing to risk spills and the wrath of environmental regulators while the system deteriorates.
You don't have to be an engineer to realize that the city's sewer pipes are showing their age. Pictures tell the story.
Cameras sent through the city's pipes during the past few years show dozens of lines with holes, cracks and other serious problems. Surveyors found at least four segments of pipe had disappeared entirely. More than 13 miles of pipe needed to be fixed or replaced due to structural defects, and these lines were made of clay, not concrete. Based on age alone, an additional 63 miles of pipe installed before 1960 was tagged for replacement by URS Corporation, a consulting firm hired by the city to assess the condition of the sewer system.
In the space of one year, the need for critical repairs has shot the sewer department's five-year capital budget from $527.4 million to $660.6 million. Over the next five years, the city will spend 45 percent of that money on repairs and rehabilitation, three times the amount earmarked for expanding the sprawling system.
The news got even worse in March, when the sewer department banned new access to lines after URS reported that 30 miles of pipe were either above capacity or had reached critically high levels. Some of the numbers were astronomical: Using a computer model, the consultant found one eight-inch diameter pipe was being pushed to nearly 1,600 percent of its capacity. After a field inspection, the mileage of over-capacity pipe was cut in half, which was expensive enough. The City Council has approved $63 million for immediate repairs.
When lines reach their limits, raw sewage either backs up until it reaches less-constrained pipes, or it rises into manhole shafts, or, in the worst-case scenario, it overflows into streets, yards or buildings via toilets, sinks and shower drains.