What Happens If You Hit Rock When Digging a Pool?
It is one of the most common questions we get asked at Countrywide Pools, usually right before a client signs off on their quote: "What happens if you hit rock when digging the pool?"
Fair question. Especially out here. Our Northam-based team installs fibreglass pools right across regional WA, and the ground under a Wheatbelt farmhouse or a country town block is a very different story to a flat sandy site in Perth's inner suburbs. Rock, clay, gravel and granite are all part of the job.
Nick (co-owner) has always said, "We've never had a pool we've not managed to get in." That is still true. But two recent jobs, one in Narrogin and one in Cunderdin, have tested it harder than ever.
Here is what actually happens when we hit rock, what it means for your timeline and budget, and how we work through it.
Why rock is so common in regional WA
Much of the Wheatbelt and Great Southern sits on ancient granite. You see it above ground in the big outcrops dotted across the region, and very often it is sitting just under the topsoil too. Add in coffee rock, laterite, gravel and reactive clay, and a regional pool dig can throw up just about anything.
That is exactly why we quote regional jobs differently. Rather than assuming an easy bobcat dig on sand, we allow for an excavator dig upfront, and our own fleet includes a 10T excavator, a 5T excavator and rock breaking attachments. That setup gets through most of what regional WA throws at us. Earlier this week our 10T chewed through a band of coffee rock on a job in Wundowie without too much drama.
Most of the time, that is the end of the story. Occasionally, it is not.
Why rock can't be fully priced into a pool quote
Here is the honest answer: nobody knows exactly what is under the ground until we start digging.
We look at the site, check what we can see on the surface, talk to the owner about what they found when the house or shed went in, and use what we know about the area. That lets us make an educated call and set realistic allowances. But a few metres down, a site that looks like loam and gravel can turn into a solid sheet of granite.
That is why most pool builders, us included, treat rock that goes beyond what our standard excavation gear can handle as a variable. We would rather be upfront about that from the first conversation than bury it in the fine print. If you want to know more about what is included in our regional pool quotes, we are always happy to walk you through it line by line.
What happens when we hit rock: Plan B, C, D and sometimes E
When the excavator stops making progress, we stop and reassess. The options usually look like this:
• Break it out with the excavator. Our rock breaking attachments handle a lot of what we find, including most loose or fractured rock and coffee rock.
• Shift the pool. Sometimes moving the pool a metre or two, or changing its orientation, avoids the worst of it. We always talk this through with you before making any changes.
• Rethink the design. In some cases a different pool shape or depth profile can work with the site rather than against it.
• Go through it. When the pool has to go exactly where it was planned, we bring in the heavy-duty approach.
Whatever the plan, you hear from us straight away, with a clear explanation of what we have found and what each option means for time and cost.
Narrogin and Cunderdin: when the excavator wasn't enough
On both of these jobs we hit solid granite across roughly 90% of the hole. We are talking solid sheets of granite, wall to wall. And on both sites, the pool needed to go exactly where it had been planned, so moving it was off the table.
So we invested in our newest fleet addition: our own rock drill. The process goes like this:
• Drill. We drill a pattern of holes into the granite.
• Grout. The holes are filled with an expanding grout.
• Wait. As the grout cures it expands and cracks the rock from the inside. This part can't be rushed.
• Break. We get back in with the rock breaker to remove the cracked rock.
• Repeat. Then we do it all again, layer by layer, until we reach the depth we need.
It is slow, hard work, but it gets the job done. The Cunderdin pool is now complete, and after four trips to site to work through the granite, the Narrogin pool goes in next week on visit number five.
What hitting rock means for your pool project
Timeline: Hard rock can add days or, in the toughest cases, extra site visits to the excavation stage. For remote sites that also means more travel and mobilisation, so we plan each trip to get as much done as possible.
Cost: Rock removal is costed on a case by case basis. It is impossible for us to say in a blog that "it will cost X amount", because it depends on the size of the rock, how deep it goes, how hard it is and what method is needed to get it out.
What we can tell you is how it is charged. As SPASA members, we use the SPASA contract, which sets out how rock and excavation charges are handled before any work starts. It is all laid out in the contract upfront, so we are all on the same page from day one and you won't be hit with any nasty surprises.
If more specialist removal is needed, like rock drilling and grouting, we can normally give you an estimate beforehand once we have uncovered the full shape of the rock. That way you can make an informed decision before we go any further.
The finished pool: Once the hole is right, the rest of the install carries on as normal. Rock has no effect on the quality or lifespan of your new fibreglass pool.
How to reduce the risk of rock surprises
• Tell us what you know. If you hit rock putting in a septic, shed footings or a bore, mention it at the site visit.
• Look around. Granite outcrops, rocky paddocks or shallow topsoil nearby are all clues.
• Be flexible on position if you can. A pool that can move a few metres gives us more options if we hit something.
• Choose a builder set up for regional sites. A company that owns the right machinery and knows regional ground conditions will handle rock far better than one relying on a basic metro setup
Frequently asked questions
What happens if you hit rock when digging a pool?
The builder stops and assesses the rock. Depending on how hard and widespread it is, it may be broken out with an excavator and rock breaker, the pool may be shifted or redesigned, or specialist methods like rock drilling and expanding grout may be used. A good builder will talk you through the options before going ahead.
Who pays for rock removal when installing a pool?
Rock removal is usually charged to the client, and how it is charged should be set out in your contract before work starts. As SPASA members, we use the SPASA contract, so rock charges are laid out upfront. If specialist removal like rock drilling is needed, we can normally give you an estimate once the full shape of the rock is uncovered.
Can you tell if there is rock before digging a pool?
Not with certainty. Surface clues, nearby outcrops and past digging on the property all help, but the only way to know for sure is to dig. Experienced regional builders can make an educated assessment and set realistic allowances.
How long does rock removal add to a pool installation?
It depends on the type and amount of rock. Rock that an excavator with a rock breaker can handle may add very little time, while solid granite needing drilling and expanding grout can add several days or extra site visits.
Can a fibreglass pool be installed on a rocky site?
Yes. Once the excavation reaches the right depth and shape, a fibreglass pool is installed on a properly prepared base just like any other site. The rock only affects the digging stage.
Worried about rock on your property?
Countrywide Pools has the machinery, experience and honest advice to handle tough regional sites. Tell us about your property and we will give you a realistic, site-specific quote.
