Backfilling a Pool


Backfill a Pool With Dirt is a process, and backfilling is a process all pool owners must be aware of.

If you’re hiring a builder to do it for you, make sure they are transparent with the process—especially when it comes to knowing how to backfill a pool with dirt. 

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Demolition TypeCost
Partial Collapse and Fill $2,500 – $5,000
Partial Collapse and Engineered Fill $6,000 – $8,000
Full Collapse and Fill $9,000 – $19,000
Full Collapse and Engineered Fill $19,000+
Material Used
Sand
Gravel
Dirt

That said, it’s best to familiarise yourself with what goes behind the process of backfilling a swimming pool. 

What Is Backfilling? 

As its name suggests, backfilling is simply filling up a remaining space with either gravel, sand, or dirt. There are two situations wherein backfilling is required—installing and removing a pool. 

When installing a pool, the builders must first create a space for the pool by excavating the ground. The extra width of at least 3 feet is usually dug up to make way for plumbing. 

That extra width will eventually need covering up. Hence, the backfilling. On the other hand, backfilling for pool removal is a whole other process. We’ll explain later in the article. 

Commonly Used Materials for Backfilling 

Some fills work better than others. If we’re on the topic of pool installation, sand and gravel come to mind. On the other hand, Pool demolition requires a varied mix of dirt, topsoil, or tailings. Let’s discuss each one. 

Dirt

First of all, using dirt as backfill for pool installation is a no-no. You will hear some pool owners—or even builders—insisting that dirt is practical for backfilling a swimming pool due to lower cost. 

But really, it’s just not. 

The main problem with dirt is it takes a while to settle. Because dirt is mainly granular, it shifts loose and doesn’t pack densely. 

Simply put, it’s unstable. 

Dirt settles very slow, taking around weeks—or even months—before it fully compacts. As a result, this leaves a gap underneath the surface, making the foundation very weak and wobbly.

If you happen to run into a contractor who pushes for dirt backfilling, it’s best to steer clear from them. While it’s tempting to get a low quote, you’ll end up paying for additional costs when your dirt-laid foundation gives up on you.

Using dirt for pool demolition is a whole other topic, however. It involves a mix of regular dirt, fill, tailings, and topsoil.

When ordering your fill, an ideal ratio would be 80% fill/tailings and 20% topsoil for the surface. 

Sand 

Sand premixed with cement provides a very compact mixture. Meaning, it has a low chance of settling, unlike dirt. 

This is why many pool manufacturers recommend having their product paired with a sand backfill, especially for fiberglass pools. 

However, there is an apparent downside to using sand. 

When sand starts to hold too much water, it becomes heavier than the water sitting inside the pool. The result? Inward bulges from the walls of your pool. 

Gravel

Gravel is an entirely different property compared to sand. Unlike sand, which is particularly granular, gravel is made up of stones. 

This composition allows for two advantages: 

  • Instant compaction
  • Efficient water draining

Instant compaction means gravel immediately settles when poured onto the excavated area. Of course, to be sure, you would still need a compactor.

This is to level the gravel and to make sure no gaping spaces are left for the gravel to shift in. 

Efficient water draining is another advantage of gravel. Unlike sand, gravel does not absorb water. It simply allows water to pass through the small cracks between the stones.

In other words, you will not experience unsightly pool wall bulging as gravel does not create water pressure outside of the pool. 

Backfilling A Swimming Pool Demolition

There are many reasons for undoing a pool installation. One of the main factors is high maintenance costs. 

But whichever it may be, a backfill is always a good way to close your pool permanently. 

Partial Collapse and Fill 

This is the most common pool demolition process. A partial collapse and fill involve a couple of steps: 

  • Jackhammering the pool floor
  • Filling it in with dirt
  • Compacting the dirt
  • Breaking the pool sides
  • Backfilling and compacting
  • Applying topsoil

It’s the cheapest and fastest way to remove a pool, taking only about 2-5 days. On top of that, you don’t need an engineering technician to oversee the procedure. 

However, there are downsides to partial collapse and fill: 

  • The backfilled area will no longer be buildable
  • Can affect the value of your home
  • Risk of depressed area or swelling when done incorrectly

Because of the many risks involved with a partial collapse demolition, you would have to ultimately disclose to your future buyers that a pool was once built there. 

Cost: $2,500 – $5,000

Partial Collapse and Engineered Fill 

This procedure is pretty much the same as above. The only difference? An engineer will be assisting during the backfill process. 

Usually, you only opt to do this if your city requires it. 

Note that even with engineered fill, you would still have to declare the backfilled area as non-buildable. This also means that it will still negatively impact the value of your property, and you would still have to disclose this to your future buyers. 

Full Collapse and Fill 

This process involves removing every last part of your swimming pool and then filling it afterward. Depending on where you live, your state may either consider the area buildable or not.  

You might be wondering, why opt for a full removal when a partial one is available at a cheaper cost? 

There are advantages to having your pool completely removed. As mentioned earlier, depending on your state, you can declare the backfilled area completely buildable. 

Second, chunks of concrete can settle over time, eventually causing depression on the surface. When a complete pool removal takes place, zero traces of concrete will be left behind. As a result, there will be lesser room for error during the backfill process.

Cost: $9,000 – $19,000

Full Collapse and Engineered Fill 

The only surefire way to declare your area ‘buildable’ is to undergo this procedure. A full collapse with engineered fill is exactly what you think it is. 

Your contractor will remove every last trace of your pool and backfill it, complete with the assistance of an engineer. 

While this is the most expensive option, it’s also the best procedure. Having your area declared ‘buildable,’ you won’t have to worry about compromised home property values or other problems. 

A Few Notes 

If you plan to have, your pool demolished, note that the pricing depends on many factors, including your pool material. 

Is your in-ground pool made of fiberglass, concrete, or vinyl? If your pool is made of concrete, expect the price to increase due to the added resources needed to obliterate a concrete pool. 

All in all, pool backfilling is only a part of a bigger process. Pool installations and removals, while completely DIY-able, should only be done by professionals if you do not have the skills. 

And let’s face it—most of us probably don’t. It’s always best to pay for a very delicate procedure that may largely compromise safety if not done properly.

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