The current common practice for constructing arenas is based on road making. The process consists of:
- Levelling the site
- Putting down layers of coarse rock
- Putting down layers of finer rock
- Adding the surface
It is worthwhile to schedule a fair bit of time (in the order of a week) between the completion of compacting and the first trucks arriving on site to commence construction. This time is to allow the base to dry out and ensure it is solid. Alternatively, you can finish the levelling and compacting of the surface after the shed is constructed. Be aware that you can't roll too close to the footings.
Drainage is another critical aspect of an arena. Good arenas are easily destroyed by water seeping under the edges. So it is essential that the arena be higher than the surrounding ground and that there are adequate drains to take surface water away from the arena.
When things go wrong
Unfortunately our base got too wet and some of the larger stones rose into the smaller stone layers. The fix was to add an additional layer of very fine stone (less than 5mm) optionally with a bituminous emulsion to bind the layer together. This creates an impervious layer that keeps the large stones down. The surface of this layer needs to be protected from direct contact with horses hooves to prevent wearing.
Dust is a continuous problem with indoor arenas in particular; we applied a layer of Dustex (lignosulphonate) from Dustex Australia (http://www.dustex.com.au/) to reduce the amount of dust that comes up from the base and through the surface. The Dustex also aided in repairing the base when a beam was dropped on to it as we could recompact the disrupted area and effectively glue the base back in.