[News in The Villages]

Depressions drained water from Basins 3-2 and 3-9 this fall; one repair is already done and the other awaits approval Friday.

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[BrianL99]

Originally Posted by The Gazette

Depressions drained water from Basins 3-2 and 3-9 this fall; one repair is already done and the other awaits approval Friday.

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"The water loss also caused a 24-year-old, 48-inch metal stormwater pipe to collapse after it lost the water pressure that supported it, the report says."


Odd design.

[Bill14564]

Originally Posted by BrianL99

"The water loss also caused a 24-year-old, 48-inch metal stormwater pipe to collapse after it lost the water pressure that supported it, the report says."


Odd design.

I'm still trying to figure out what created pressure inside a stormwater pipe. If it was simply gravity-fed into the ponds then there was no pressure in the pipe at all.

Perhaps the loss of water revealed that the pipe had collapsed.

It would be even more suspicious if the sinkhole was adjacent to the collapsed pipe.

[Jayhawk]

Originally Posted by BrianL99

"The water loss also caused a 24-year-old, 48-inch metal stormwater pipe to collapse after it lost the water pressure that supported it, the report says."


Odd design.

Odd design that lasted a quarter of a century.

[randykw]

Located in my Village of Summerhill. It STUNK at first when all the fish were decaying. The District did take care of the stinky mess.

[BrianL99]

Originally Posted by BrianL99

"The water loss also caused a 24-year-old, 48-inch metal stormwater pipe to collapse after it lost the water pressure that supported it, the report says."


Odd design.

Originally Posted by Jayhawk

Odd design that lasted a quarter of a century.

It lasted until there was a catastrophic failure. There are really only 2 reasons for spontaneous catastrophic failures ... poor design or poor installation.

Typical design lifetime of municipal drainage systems, is 50-100 years.

CMP pipe is not designed to be "supported by water pressure" and the expected service life of properly installed CMP, is closer to 50 years than 24 years. If it was Type 2 CMP, closer to 75 years.

If the newspaper reporting is accurate, a more appropriate engineering spec might have been RCP or another alternative. Of course, CMP is one of the cheapest options & you usually get what you pay for.

[Sit U 8]

Originally Posted by BrianL99

"The water loss also caused a 24-year-old, 48-inch metal stormwater pipe to collapse after it lost the water pressure that supported it, the report says."


Odd design.

For sure.
Wonder what material it was?

[BrianL99]

Originally Posted by Sit U 8

For sure.
Wonder what material it was?

It was described as a "24 year old metal pipe". Used in that application, one would assume it CMP (Corrugated Metal Pipe) ... which is the typical drainage pipe you see, with the circular reinforcement around it.

That metal drain pipe comes in at least 3 variations. Uncoated Galvanized CMP, Aluminized Type 2 CMP & Polymer-coated CMP.

The next step up in common usage, would be Reinforced Concrete Pipe (RCP) or HDPE stormwater pipe, the last 2 have a service lifetime or 75+ years.

I've never heard of a 48" pipe being "supported by water pressure" as described in the Newspaper report. While water pressure provides some structural integrity if constant, it's hard to believe that was its source of support. Who knows? I'm not an engineer, but I've installed or had installed, 1000's of feet of drain pipe.

[Topspinmo]

Originally Posted by Bill14564

I'm still trying to figure out what created pressure inside a stormwater pipe. If it was simply gravity-fed into the ponds then there was no pressure in the pipe at all.

Perhaps the loss of water revealed that the pipe had collapsed.

It would be even more suspicious if the sinkhole was adjacent to the collapsed pipe.

Pressure from the weight of the water above transfer CMP. Just like a water tower, anything lower than tower storage has pressure in it.

[Topspinmo]

Originally Posted by BrianL99

It lasted until there was a catastrophic failure. There are really only 2 reasons for spontaneous catastrophic failures ... poor design or poor installation.

Typical design lifetime of municipal drainage systems, is 50-100 years.

CMP pipe is not designed to be "supported by water pressure" and the expected service life of properly installed CMP, is closer to 50 years than 24 years. If it was Type 2 CMP, closer to 75 years.

If the newspaper reporting is accurate, a more appropriate engineering spec might have been RCP or another alternative. Of course, CMP is one of the cheapest options & you usually get what you pay for.

IMO failures will happen where ever CMP used as storm water transfer pipes submerged under weight ponds. District 4 has two classic examples. Failures seems to be on around 25 year cycle based on failures so far.

“AI”piping used in Florida

(“ Yes, Corrugated Metal Pipe (CMP) can be used for underwater water-transfer culverts in Florida, provided it is restricted to non-pressurized gravity flow and uses corrosion-resistant materials. “Standard galvanized steel CMP is generally avoided”. in submerged Florida environments due to rapid rusting, whereas Corrugated Aluminum Pipe (CAP) and polymer-coated steel are widely approved for freshwater, brackish, and saltwater applications.

Key Requirements & Restrictions

Whether CMP is allowed and how it must be built depends heavily on the type of water, pressure, and permitting agency:
• Gravity Flow Only. CMP is designed for open-channel stormwater drainage, pond interconnects, and tidal equalization culverts. It cannot hold internal water pressure and is strictly prohibited for pressurized potable water mains, force mains, or pumped transfer lines.
• Material Selection for Florida Waters. Florida's high water tables, acidic soils, and coastal saltwater severely shorten the lifespan of standard zinc-galvanized steel. For submerged installations, engineers typically specify Aluminum Alloy (such as CORLIX) or Polymer-Coated / Aluminized Steel Type 2 (ALT2) to achieve a 50- to 75-year service life.
• Watertight Joints. Standard culvert bands allow soil infiltration and exfiltration. Underwater transfer pipes require watertight gasketed coupling bands (such as O-ring or hugger bands with neoprene gaskets) to prevent sediment from washing into the pipe and causing sinkholes above the trench.
• Buoyancy & Anchoring. Because empty or partially full CMP has high buoyancy when submerged, installations below the water table require sufficient backfill cover, concrete headwalls, or anti-flotation collars so the pipe does not float out of alignment.”)

[BrianL99]

Originally Posted by Topspinmo

Pressure from the weight of the water above transfer CMP. Just like a water tower, anything lower than tower storage has pressure in it.

According to the newspaper source (which is the only information I have), the pipe is typically full of water, which would under normal circumstances, provide additional structural integrity. The pipe wasn't getting any water, which compromised the structure.

Envision trying to crush full can of soda vs an empty can. The full one is structurally stronger.

CMP is fairly thin and derives much of its strength, from the surrounding soils, compacted around it. Reading what the newspaper wrote, suggests that in this case, the structural integrity of the pipe, was based on it being surrounded by water ... once that changed, the pipe failed.