After many years of use, a pool’s going to need some repairs.
But one repair you may have not planned for, and certainly one you don’t want to deal with, is your pool popping out of the ground.
It can be downright catastrophic and look like an earthquake localized around your swimming pool.
What Is Pool Popping?
Pool popping is when the entire pool literally lifts (or pops) out of the ground.
So how common is this phenomenon? Not very, actually.
However, you should still be aware of how a pool pops out of the ground, so you can take the proper precautions and avoid ending up with an unplanned semi-inground pool.
What Causes A Popped Pool?
The most common time a pool will pop is during a pool drain.
When pool water can no longer stay clean using sanitizing chemicals like chlorine, it needs to be swapped out. Drains are also done when the pool requires some extra TLC in the form of pool repairs or surface washing.
It’s extremely rare that a pool will pop when it’s full of water, as the average pool is weighed down with over 250,000 lbs. of force. However, when there isn’t any water, it invites potential catastrophe due to the following reasons:
Hydrostatic pressure is the force that water exerts on other objects when it’s not in motion. It works two ways with swimming pools.
First, when a pool is full of water, the hydrostatic pressure pushes against the walls and floor of the pool from the inside, weighing it down. At the same time, groundwater pushes against the exterior and underside of the pool.
When the pool is emptied, there’s no more hydrostatic pressure inside the structure. At the same time, if there’s an influx of groundwater, the exterior hydrostatic pressure will cause the pool to crack, bulge, or float (pop).
For this reason, pools are equipped with hydrostatic relief valves (or plugs), located on the pool floor. Opening them when the pool is empty allows the groundwater to swell into the structure, relieving the pressure, and ensuring your pool stays put.
If you’re installing a new pool, make sure it has hydrostatic pressure relief valves to save you from a world of pain in the future.
Soil that has a high potential for swelling (usually with a high clay content) is something you should be concerned about as it can lead to a pool popping out of the ground. The soil’s absorbent quality allows it to swell up or shrink in relation to how much moisture is present.
If moisture levels get too high, the swollen soil causes the structure to shift. This can result in major structural damage to the shell of the pool as well as the pipes.
Pool installation companies should plan for this though. They’ll over-excavate the area to remove any expansive soil that may be surrounding the structure, and install a more pool-friendly soil in its place.
Draining your swimming pool is only recommended when you have ideal, cool weather, and during a stretch where there hasn’t been, or will be any rain.
In extreme weather conditions, such as heavy rains or thunderstorms, flooding can easily occur due to a large influx of rain. This sudden swell of water in the ground soil will accumulate until it pushes the pool up, popping it out of place.
High Water Table
Water table is the underground boundary line that divides the soil surface from the area where groundwater saturates the spaces between sediments and cracks in rock. It’s also another cause of pool pop.
Due to changes in the weather, such as droughts or seasonal rain, the water table level will fluctuate, sometimes being low, while high at other times. A high water table can also be caused by underground springs or the general geographic layout of the area.
You can counteract this by installing a dewatering system for your pool, which essentially activates a dedicated pump (such as a sump pump) to remove excess water when the water table level gets too high.
If The Worst Happens…
You have a few options when it comes to fixing a pool that’s gone belly up, though they may not be the easiest or most cost-effective fixes, and they also depend on how severe the damage is.
One way to fix it requires you remove the entire pool deck so you can lift the structure out, re-dig, and level it off so the pool can rest at the proper grade again. The deck is then reinstalled to cap it off.
The other method requires capping the pool using cantilevers, making all the edges level with the highest corner of the pool. This method will require additional materials in order to give the pool a strong bond again.
Unfortunately, in many cases, a popped swimming pool means you might have to start your build from scratch.
Pop Goes The Weasel
A pool popping out of the ground is never a good thing, and hopefully you’ll never have to deal with it happening to your swimming pool.
Fixing them will cost thousands of dollars, and it might actually be more cost-effective to start over.