POSTED ON MAY 9, 2007:
But not very afraid. No, the sky is not fallingWith the city budget so tight, however, you might be on the lookout for gaping holes beneath your feet
The deadliest instance of sinkholes occured in Guatemala, where more than 1,000 people had to be evacuated after the earh collapsed into a 330-feet deep gorge.
All over the nation and elsewhere for the past year, as numerous people went about their daily routines of going to work, picking up their kids from school, buying groceries, running errands and living their lives, they were swallowed up without warning by holes suddenly appearing in the ground beneath them.
In Portland, Oregon last December, a 50,000-pound sewer truck was swallowed whole along with two city workers by a suddenly appearing chasm.
In Los Angeles, half of Pacific Coast Highway had to be immediately shut down lest motorists disappear into a gaping abyss that suddenly appeared last year.
A 64-year-old woman in Brooklyn fell into a pit that had appeared overnight in front of her home.
The deadliest instance occurred in Guatemala, where more than 1,000 people had to be evacuated after the earth suddenly collapsed into a 330-feet deep gorge, killing two people as it swallowed them along with about a dozen homes.
It sounds like the premise of some B-rated, straight-to-video horror movie in which some unknown, malevolent entity attacks hapless victims from beneath.
While there is certainly drama involved, there's nothing fictional or scripted about this phenomenon, though. The above-referenced scenarios are well-documented facts.
So, what's causing it?
Giant, hungry worms from beneath?
The wrath of God?
None of the above, actually. Broken sewer pipes are to blame for wreaking so much havoc.
When a pipe breaks, flowing sewage carries off dirt that falls into the crack. As that dirt is whisked off within the pipe, more dirt falls into its place, which is also carried away.
As more and more dirt is carried away in small quantities over extended periods of time, less dirt remains to support the surface above, and it's only a matter of time before the ever-growing cavern, or pocket of increasingly loosely packed dirt gives way, creating a sinkhole.
While broken pipes generally wouldn't make for a very interesting horror movie, as silly as it might sound, the situation is still no less threatening than if giant, voracious sandworms actually existed and were attacking from beneath.
Sometimes sinkholes are minor, barely discernible depressions in the ground. Sometimes, though, they're big enough to destroy property and lives, as the past year has shown.
And it's in the last year or so that the problem has been the worst. "The Year of the Sinkhole" the phrase used by Thomas Rooney, president of the St. Louis-based Insituform Technologies, to describe 2006 in an opinion-editorial for the L.A. Times.
Almost every state in the nation experienced record problems with sinkholes, he wrote.
The reason is that time is catching up with sewer systems that were installed almost a century ago, but were only meant to last about 50 or so years. Badly maintained sewer systems are one of the most critical infrastructure problems in the nation, according to the American Society of Civil Engineers.
"This is a huge problem across the United States," said Jeanette Brown, president of the Environmental and Water Resources Institute, an affiliate of the ASCE.
Brown is also the executive director of the Water Pollution Control Authority, which is the agency responsible for maintaining the sewer system in Stanford, Conn.
She said older pipes made of reinforced concrete usually last about 50-60 years, while more modern, plastic pipes last much longer.
"It's more than just the age of the pipes," Brown explained. "It's even more complicated than just that--it's also how well maintained they are," she said.
Brown said the older, clay tile pipes that were installed in the early part of the 20th Century have a tendency to break down with age, but "even some of the more modern systems can deteriorate," depending on how well they're maintained.
And many sewer systems, old or new, just aren't maintained as well as they should be, she said.
"Certainly the investment of communities (in sewer maintenance) is relatively low," said Brown.
"The pipes are under the ground and nobody sees them--you don't have mothers and fathers coming to city council meetings to complain about the condition of sewer pipes the way they do for their kids' school bus or for roads," she added.
"It's not a sort of sexy subject, so if cities have pressure on their budgets they're only going to think about this when something dramatic happens, like sinkholes or sewage backing up into people's toilets," Brown said.
Pestilence and Disease
Sinkholes and backed-up plumbing aren't the only forms of drama that can ensue, though. The Environmental Protection Agency estimates that 3.5 million people got sick with E. Coli and other toxins last year from 40,000 sewage spills.
However, Brown said, while E. Coli breakouts resulting from broken sewer pipes are not unheard of, "it's not a very widespread problem."
She said it normally only happens if the spill occurs in proximity of a population's groundwater source.
The City of Tulsa has 1,900 miles of sanitary sewer pipes, said Mark Rogers, underground collections manager for the Tulsa Public Works Authority.
Many of those pipes were installed during the building boom of the 1970s, he said, and have life expectancies of about 100 years.
He said there have been 20 reports of sinkholes in Tulsa in the past year. Of those, eight were from privately owned pipes and not under the city's purview, seven were over storm drainage pipes and five were over sanitary sewage pipes.
Rogers said the number of sinkhole reports was "about the same" as in previous years.
Some of those reports concerned nothing more than minor annoyances, with a typical sinkhole specimen spanning anywhere from about a foot to six feet in diameter, Rogers said.
Some sinkholes had the potential to be much more trouble for hapless Tulsans than the standard version, though.
"That was a pretty significant sinkhole," said Rogers of the cavity that resulted last month from a break in a 42-inch pipe beneath 61st St. at Utica Place.
The hole was about 13 feet deep and about 10 feet across.
Rogers said there wasn't any serious damage apart from a sunken power pole.
However, if a 13-foot hole suddenly appeared, say, in the middle of a busy road at night or under a home with sleeping children, the results might not be so harmless, as incidences across the nation and in Guatemala indicate.
Rogers said sinkholes aren't likely to suddenly appear in Tulsa, though.
"I don't think something's going to come up and surprise us," he said. "We knew the deterioration had been happening in that 42-inch pipe and we had requested funding to fix it," he added.
When a pipe breaks, his department usually has to dig down to replace it, Rogers said, but they also have trenchless technology at their disposal, which involves inserting a liner into the existing pipe to seal the breach.
Rogers said the city's budget this year for maintenance and replacement of sewer pipes is $18.5 million.
But, is that enough?
"Naturally, I'd say 'no,'" he answered.
"I make requests for personnel and replacement equipment all the time. I'm having to go longer and longer on the same equipment."
Is it possible sinkholes could occur from broken pipes they've missed?
"Sure they could, but we have an aggressive program inventorying those," he said. "I don't think there's any need for great alarm," he added.
Sinkholes comparable to what occurred in Guatemala aren't possible in Tulsa, he said, because the sewer pipes aren't deep enough to cause a hole of that magnitude.
Most of Tulsa's pipes, Rogers said, are eight to 15 feet deep, although some are as deep as 40-60 feet
Something on the order of Los Angeles' traffic-stopping abyss is also highly unlikely, though.
"The soil in California is also prone to mudslides, but we don't have those here," said Rogers. "I've worked in this group for 16 years and we've never had anything that compared."
The recent sinkhole at Utica Place, though, was "the biggest we've had in ten years," he said.
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