Dr. Ann Swinker put her riding arena on top of a mountain, on limestone. “It drains so well. It can be raining, and our horses can be working,” she said.
Not all sites are so problem-free. “Look at your topography and work with your contractor before you start construction,” Swinker advised. “Drainage is very important. If there is a nearby hillside, be sure it doesn’t drain largely onto the area you have chosen.”
Additionally, look at where your chosen site may drain. At one outdoor arena, much of its limestone screenings flowed onto a highway. The EPA shut down both the arena and the highway.
It can be a good idea to create a crown down the center line of your arena area, with drains running along each side to collect the water and carry it away. If it’s easier to slope it all downhill on one side, do that. Some people even put in pipes and a sump pump. Plan in advance with your contractor so you have some idea of the cost.
When you start construction, take off your top soil and sell it. The top soil is worth more that way, and if you construct on a subsoil base, you’ll need a lot less rock. A specialized geotextile placed on top of the remaining subsoil is a good idea, because it keeps the rocks that you truck in as a base for your arena from mixing with your subsoil. Do not use weed barrier fabric.
Some indoor arenas use geogrids to enhance drainage and keep the surface level. A geogrid has large apertures with longitudinal and transverse reinforcements, so that corners, for example, are less likely to wash out. Typically the geogrid is filled with 4 to 6 inches of 2B or 1 1/2 B rock, with 2 to 4 inches of screening sand on top.
Trucking will be your biggest cost, so look around for what is available locally. There is nothing wrong with using limestone screenings instead of sand, but keep in mind that they are not as forgiving as sand on barefooted horses.
Limestone screenings may be best when mixed with sand. In fact, Dr. Swinker continued, “I mix limestone screenings with the sand on my mountain top to keep the lightweight sand from blowing away.
“I have really fine, soft sand. I’m working with young horses. I don’t want to use shoes on 2-year-old horses. So the bottom line is that, to some extent, the materials you use in your riding arena will depend in part on how you want to use it.”
You can use the same formula you use for your sacrifice areas or around the barn to keep your horses out of the mud. Just pack it in tighter in the arena, because horses excavate a lot when they’re on the run.
Pack size 2B or B stone with a mechanical roller, for example. Then just sprinkle the top surface on. You want the top surface to stay loose. If it compacts (which is more likely with a full range of particle sizes), your drainage will be reduced.
“The key is to come up with a soft, foot-friendly, firm surface that drains well,” Swinker added.
Sand over a good solid base is the gold standard in footing material, either alone or mixed with other materials. Across the U.S., 70 percent of the arenas use sand.
But not just any sand. The sand you use should be clean, screened, medium coarse, hard and sharp. “You don’t want round sand grains. They will roll around and change your depth, and also roll outside your arena.”
Sharp sand has jagged edges that will hook together and not change your depth much, even when you’re driving and lunging. Coarse sand is also better for draining.
To determine sand depth, consider how you’ll use your arena. Dressage horses don’t like too deep a footing. Jumping horses like a footing about 2 inches deep that is flat and packed firm. Barrel and roping horses put a lot of strain on their joints. They like a 4-6 inch deep soil/sand mix that is packed firmly.
When you’re constructing your arena, don’t let the trucker just spread his whole load of sand over the surface at once, Swinker advised. Spread on about 2 inches, then check it, and bring in your horse to try it out. Then spread another inch, if needed, and so on. If you put on too much sand, it’s really hard to remove it and re-level the surface.
Sawdust or wood chips, a second possibility for your footing for an indoor ring, are usually mixed with sand or limestone screenings. The wood fibers add cushioning and hold moisture. For outside use, though, wood fibers can hold too much moisture, resulting in slick spots. They also break down over time.
Rubber can also be mixed with your footing surface, although with rubber from shredded tires, Dr. Swinker would worry about bits of metal from the steel-belted radials. The grading people don’t like rubber, and using a lot of rubber can result in a surface that is too cushy. Rubber will not degrade, but it will break down, and if you use a lot, black dust can color your clothes, your equipment and even your horses.
Eighty percent sand mixed with 20 percent clay is a mixture many trainers like. However, when dry, the clay particles can get into the air and be inhaled, resulting in respiratory problems. Clay also becomes slippery when wet.
Man-made synthetics, like shredded polyester and cellulose fibers mixed with sand can be okay for indoor rings, but generally not for outdoor ones. Used indoors, the fibers help to stabilize the sand grains and can give a bouncy ride.
Stall waste is the cheapest and most challenging footing. Composed of wood chips and urine mixed with clay, stall waste is sometimes composted. Some people, in winter, take the waste right out of the stall and into the arena.
“Stall waste does a fabulous job of dust control, but it smells awful, and the odor lingers on your clothes. The bacteria in stall waste are a health hazard, and can cause rhinitis and bronchial pneumonia,” noted Swinker. The cheapest is not always the best!