Quote for groundworks to semi-sink a swim spa.

Please find attached a photo of the area and an outline of where the swim spa would go, not to scale. Red arrows where drains run.

This is to dig down 85cm and lay a 15cm reinforced concrete pad with retaining wall and drainage. The total dimensions from within the walls for the spa to sit would be 255cm wide x 475cm long x 70cm high.

It would be great to get a quote for this if possible please.