We are in the process of ordering the fill for the Ladies run. We were leaning towards sand after reading so many great experiences with the sand. We have been calling everywhere and no one around here has heard of River Sand. They actually laugh saying they never heard of it. We were wondering if Pool sand, the sand placed under an above ground pool liner, would be safe for the Ladies. We would like to add the fill before we finish the sides of the run. As you can see we are still working on this.