Sand school project

[Gene2012]

Please could you advise me on the best way forward to making a small lunging/ school area approximately 25ft x 25ft The ground has an underwater spring that runs 15 feet along the stretch of ground I want to put the school. The soil is heavy clay and holds water. Is this a bad idea or can this be achieved?
Thanks for reading.

 

[Mainland]

25ft?? Do you not mean metres?

 

[Gene2012]

Yes I do mean metres, Thanks