Concreting around a storm water pit?

[DaveU]

We've just had professionally installed a new storm water pit, and need to seal around outside the sides where the soil and small stones are so water doesn't get in. Am I correct in assuming regular concrete would suffice or would anyone recommend something different?

[Jason]

Welcome to the Bunnings Workshop community and apologies for the slow reply @DaveU. It's great to have you join us and we look forward to reading more about your projects and plans. Please don't hesitate to post whenever you need a hand or have something to share. 

The ever-helpful and knowledgable @MitchellMc will be back on the site tomorrow and I'm sure he would be happy to assist. In the meantime, let me tag a few other fantastic members in @JDE, @LePallet and @ProjectPete to see how they would tackle this project.   

Please let me know if you ever need assistance getting the most from the site, or ever have any feedback about how we can ensure Workshop is even more useful to you.

Jason

[DaveU]

Thanks for the warm welcome Jason! Its worth mentioning that I live on a hill and there is a problem with some level of water getting under the outdoor steps and into the lower house level. So my thinking is to lift the top step to make sure there is no cavity for water, and fill it up with concrete and similarly directly around the new pit so it is water tight. Does that sound like the best approach?

I'm assuming regular concrete is fine, but someone might know of something better (I've used a synthetic concrete in the past which was good but I forget the name). Once done, I was thinking off reapplying fresh mortar also around the sides to further assist with sealing and directing the water flow into the pit

[MitchellMc]

Hi @DaveU ,

I'd also like to welcome you to the Bunnings Workshop community. It's great to have you join us and many thanks for your question.

You could use a standard concrete or Dingo 20kg Hi-Strength Concrete to fill that area around the stormwater pit. You'll need to dig out that existing fill to around 50mm deep as the concrete needs to sit somewhere. I don't believe the concrete will last long if you simply apply it over the surrounding area as the layer will not be thick enough.

It sounds like you have a fairly unique situation going on with the water entry into the lower house level. Adding concrete under the top step might assist with that issue, but it sounds like there is a larger-scale problem and I assume you are trying to address that with the new drainage channels and pit. You might like to take a look at some of our wall waterproofing membranes. If water is penetrating through that wall you might need to paint it with a membrane. This would most likely mean removing the stairs to get the membrane where it is needed.

You should find these step-by-step tutorials helpful: How to mix concrete and How to build formwork

Please let me know if you need further information or had questions.

Mitchell

[DaveU]

Thanks Mitchell, really appreciate your feedback.

Cheers,

Dave