I'm putting in an outdoor riding arena and looking for some information. It's acually being excavated as we speak.

The size will be 110x120 and will have a stonedust base (approx 4 in) with sand on top. Has anyone had this done? How much stonedust / sand did you add in? I was also looking at adding rubber but not until spring. Also a big question I have is what type of sand? One thing has stuck in my head for all my questions about arena's and that was a gentleman who said "all sand is not created equal." Ok so what should I use? Any recomendations on rubber? I really need to know how deep I should go with each product keeping in mind that I need to have good drainage and the top cannot freeze. Any help would be great