We would like to build large play mounds/ land forms with rubber surface on structure. Although the playground is at entry level there is a basement parking level below the proposed landscape. I requested load restrictions a long time ago and have not received any information yet. The client likes the large (2.5 m max. ht) mounds, but I am feeling fairly confident that once the load restriction numbers are available our design will have to change completely. In the mean time can any one recommend a soil alternative, or lightweight soil admixture that would be appropriate to this situation? As I understand the standard rubber surface mound is adhered to an asphalt surface, which will need a stable subgrade. Any thoughts ?