Need to fill hole then patio over

[s_workman]

Hi all.

My first post so hello.

I have dug out a 2m x 1.5m x .5m hole on a concrete patio to access the sewer pipe as we are adding an en-suite and require to run our new soil pipe.

Picture of hole

The clay section is being replaced in PVC by our plumber and encased in concrete due to the proximity to the surface and the fact that we plan to lay some nice sandstone slabs after we remove the rest of that hideous concrete.

My question is what should I fill the hole that I have dug with? The soil is very heavy clay and being a Victorian cottage the foundations are very shallow with stepped brick footers directly on to the clay from what I can see. I am worried I will damage the foundations by changing the water content of the clay or by whacking down aggregate so close to the foundations. Can I just fill with type 1 or ballast compacting every few inches or is .5m of type 1 unrealistic?

Also the current concrete is above the DPC so will be lowering everything around 8 inches.

Thanks,

Scott

[seanandruby]

DPT1 will be fine.