House build over old underground pool

Hi

Im looking at some sectioned off land where an underground pool used to be. The owners told me it was leaking and was beyond repair so they threw in tonnes of materials they didn’t need anymore like furniture, wood and bricks that otherwise would have gone to the tip. Then the rest filled with dirt. Id like to build a house on this bit of land but i am concerned about potential risks for the build.

Does anyone have any advice on how to proceed or whether it just isn’t possible? I don’t want to purchase if I cant build on it.

Thank you

Hell no.

If you want to build on that spot, you'll need to remove the dirt, debris and the pool and then properly fill and compact and an engineer sign-off on it.

You have no idea what they put in there (furniture???) and how it would stand up to the weight of a house.

They sectioned off and are selling a part of their back yard.
I think they used the pool as a quick way to get rid of their rubbish instead of taking it to the tip and to save money since they didn’t want the pool anymore.
Probably going to cost me a lot to dig it up and fill it in properly. Not sure how much out of picket ill be on that.

I'd be very wary.

Don't even consider it

If you have the money and it’s a ridiculously cheap bit of land, get a geo-environmental engineer to provide you a quote to make an assessment of the fill so you can work out disposal costs – it maybe that asbestos type of wood and those car engine type of bricks and you might be looking at a costly obligation to remediate.

If the fill is manageable, the rest is easier priced-If it went further I would look at using the pre-excavated, temporarily supported hole in the ground to construct a basement area. Better than backfilling and adds value.

Course, there is a strong possibility in a few years’ time you will be cursing yourself for thinking buying a landfill and building a house on it was ever a sane idea….

Was the pool concrete ? and did they leave the concrete base in ?

Yes the concrete base was left in. Just cracked along the base and side

Then it is difficult to install piers and you can't use conventional bored piers or screw piles. You may be able to use rock drilled piles to get through the concrete and casing to stop the fill collapsing into the excavated pier. Even if you get the foundations done well the ground around them will settle significantly over time so it will be an ongoing issue.

Another issue with piers through the fill is that you would require a dedicated piling rig which may have issues setting up on a pool full of rubbish-it can be done but the cost might be high.

The second issue with piers is that if the fill is left, there is the potential for future gas generation. Subfloor venting might be needed but designed on what and DA approval might be tricky.

I'd say all the fill needs to go.