What’s Afoot? Building a Top-Notch Arena in Eight Easy Steps
This article first appeared in The Chronicle of the Horse in January, 1990. Prices mentioned were current then – not now. Also, some new technologies, especially in footing, have been developed since then. Check around for the latest and greatest.

You’ve finally decided to build that arena you always wanted out behind the barn. You call your neighbor, the one with the tractor, and take him up on his offer to level the area for a good steak dinner and his favorite beer. Next you call the local quarry and they deliver, for a few hundred bucks, some inexpensive sand. For another dinner, your neighbor spreads the sand and bingo! instant arena, right?

You may be in for a bitter disappointment when the weather turns bad. Your neighbor never used a transit to check the grades for drainage. After the first good rain you find that Lake Superior has set up a franchise in your arena. You didn’t properly prepare the base, so when you wade out in the quagmire to dig a drainage ditch, the mud nearly sucks your boots off. You also discover that the sand you thought was a bargain has turned into something akin to a mix of oatmeal and Elmer’s Glue™. Your first thoughts are not publishable. Your second thoughts are of pulled shoes and bowed tendons.

How do you fix this mess? Or better still, how could it have been avoided in the first place?

Building a quality, functional arena is not difficult, if you do a little planning and follow some basic guidelines. After many years in the arena business I have developed eight rules for good, simple, effective arena construction.

Eight Rules for Building an Arena

Rule 1: Water in excess is an arena’s worst enemy.
Rule 2: Water has to have a place to go or it stays around.
Rule 3: Underground water is part of Rule 1.
Rule 4: Your footing is only as good as the base it sits on.
Rule 5: Not just anything will do for footing.
Rule 6: The KISS rule: Keep It Simple, Stupid.
Rule 7: Everybody’s an expert. Get advice from people who know.
Rule 8: Building an arena is a series of compromises.
Applying The Rules

Rule 1: Water is an arena’s worst enemy. Our arena at home was built into the side of a hill behind a barn. All the runoff from the hill and the barn roof ended up in the arena, along with the runoff from the driveway and the hill across from it. Locating the arena on higher ground might have prevented this from happening (see figure below).

Let’s say, though, that this is the only possible location. The solution is to make the arena an island. During the grading process, build up the pad that the arena will sit on above the immediate surrounding area and grade that area so water will flow around the arena, not through it (see figure 2, below). Use a transit, which can be rented from most rental yards, to be sure the center of the arena is not five inches lower than the sides.

Figure 2 – Cross section of arena built into hillside, with swale and French drain.

Rule 2: Water has to have a place to go or it stays around. The proper way to grade the surface of the pad, and later the base of the arena, is to put a slope on it that is enough to get the water flowing but not enough to unbalance the horses (see figure 3, below). The magic number is 2 percent. That means for every 100 feet of arena the slope will fall two feet. That may sound like a lot, but if you think of it in terms of money, it is like buying a bridle for $100 and paying $102 for the same bridle – it’s simply not worth worrying about.

Figure 3 – Top View Hillside Construction

We must also decide where we want the water to go. The principle is to get the water off the arena as fast as possible. Let’s say that our arena is a standard dressage arena, 66 feet wide and 198 feet long. If we put a two percent crown down the centerline, the water will have to travel 33 feet to get off the arena. If we tip the arena from side to side (E to B), the water will have to travel 66 feet, twice as far. If we grade the arena from end to end (A to C), the water will be forced to travel 198 feet to get out. If, as I have seen done, we tip the arena from corner to corner (M to K or F to H) the water will have to travel a staggering 209 feet. The choice is obvious, if you want the arena to drain well.

Rule 3: Underground water is part of Rule 1. The pad has been properly graded and swales have been planned to carry the surface water away from the site. Now we must deal with the rest of water that might get into the arena. The hills that drained into the arena before will soak up a tremendous amount of water during a rainy season. The water will seep into the soil and rock and then migrate downhill, underground, and surface elsewhere. If, in the grading process, we cut across these underground waterways, the water will surface right there, in the arena. The way to catch and divert the water is to install French drains around the uphill side of the arena.

A French drain is a ditch about 18 inches wide and several feet deep that is filled with drain rock and a perforated pipe. The water seeps into the ditch, then flows into the pipe and is carried away. There are some rules about French drains that must be followed. First, the drain, its shallowest point behind the arena, should be at least a foot deeper than the deepest cut made in the hillside. Second, the ditch should have a minimum slope of two percent and should hit daylight way downhill from the arena site. Third, the materials used should be of top quality. It is a lot cheaper to buy the best rock and pipe you can find than to dig the whole thing up because it got clogged.

Further prevention of clogging can be accomplished by “wrapping” the drain in a geotextile separation fabric (see figure 4). This material is a polyester felt-like material that acts like a filter. It allows water to pass through it but not the silts that will clog up the drain.

The way to use the fabric is to dig a ditch with a backhoe. Stay away from trenchers, they don’t do as good a job and make for a lot more work. Establish a grade for the ditch and make sure it is consistent. Hills and valleys in the bottom of the trench will trap water that will seep into the arena.

Line the ditch with enough fabric to overlap on top. Put a few inches of drain rock in the bottom of the trench, lay in the perforated pipe and then backfill the trench with more drain rock up to about one foot from the surface. Fold the excess fabric over the rock to keep it clean, which is the key to a good drain. Finish by filling the rest of the ditch with dirt and then shaping the swale over the top of the ditch as was planned for earlier.

A swale is a shallow gutter-like ditch that carries off surface water. To save space, the best place for them is over the drains where possible (see figure 4).

Establishing A Base

Now that the drainage problem is solved:

Rule 4: Your footing is only as good as the base it sits on. In short, dirt makes a lousy base. We must build a base that will stand up to abuse and shed water without getting soft or slippery.

There are several materials that will do the job. Every area of the country has its own version. Basically these materials are all the same stuff, a crushed, screened rock mix that contains marble sized stones down to dust in a uniform gradation. The price of this material varies as much as its name. I have paid as little as $2.65 a ton and as much as $18.00 a ton at the quarry. Freight also has a great effect on the cost, so shop around for trucking rates. [Please note: prices have changed a lot since 1990! Call around and get lots of estimates, but expect to pay more than this.]

Now that the pad or sub-base is ready for rock, we need to be sure the dirt is compacted as tightly as possible. If not, it will turn to mush under all this nice rock. The dirt should be compacted to 92 percent or better – that means really hard. It is best to have the compaction checked by a soils engineer to be sure it is right. A slip-up here could ruin the whole project.

This is where the fabric comes into play again. To build an arena that will really last, I strongly recommend the use of the fabric as a separation layer between the sub-base and the base. The fabric will prevent potholes.

A pothole forms when the very fine silt and clay particles in the dirt migrate up in to the base rock particles. This happens as a result of vibration set up by horses or traffic. Eventually there is enough build-up of silts and clays that they begin to act like grease. This causes a breakdown of the compaction of the rock. When your horse steps on that spot one too many times, he punches through the well “greased” rock particles into the mud below.

The purpose of the fabric is to separate the base rock from the dirt so the rock never gets polluted in the first place and thus lasts longer. If you have one pothole you can bet that there are several others waiting to surface. Once that process starts you will be forced to redo the entire base, an expensive process. The fabric should cost about 10 to 15 cents per square foot of arena surface.

Proper installation of the fabric is important. First, it should be rolled out and stretched tight. All roll-ends and edges should be overlapped a minimum of 18 inches. The fabric should extend two feet past the proposed fence line and the overlaps should be shingled. Start from the edge and work to the center. It helps to spread some rock along the edges of the fabric or it will tend to blow around, making for some real Keystone Cops fun trying to keep 13,000 square feet of this stuff all on the ground at the same time.

When buying fabric, look for a four to five ounce polyester non-woven filter fabric. Be specific or you may get something else. There are several types of these fabrics and not all are suitable for arenas.

Now that the sub-base and fabric are laid out, we are ready for rock. It should be spread to a uniform compacted depth of five inches or more. The softer the subbase the more rock you need. The rock supports the horses’ weight and takes their pounding. It is the foundation of the arena. If you try to cut corners here to save a few bucks, you will pay dearly later.

The fabric should extend about two feet past your fence line and should be covered with rock. The reason for this is to ensure that the edges of the base won’t break away when the horses get too close. It also saves your fence posts. If the base ends near the fence then you run the risk of run-off soaking into the post holes and rotting your posts.

Compaction of the rock is just as important as compaction of the dirt. It must be very thorough and uniform and should be better than 92 percent and as close to 100 percent as possible – again really hard. Having a soils engineer check the compaction is a good investment. When done the base should be smooth and look like asphalt.

Before we get to the footing, there are two other steps that should be done at this point. Put up your fence and install your sprinkler system if you need one. A post hole digger will drill right through the base and fabric with no problem.

Footing

Rule 5: Not just anything will do for footing. Be picky, it will pay in the long run. There are lots of different choices for footing. I will touch on the most widely used materials as there are some that I’m sure I have not seen or heard of yet. In all cases, use common sense and pragmatic judgment.

Let’s start with the ones to stay away from. Waste or dead sand is a waste product that contains all sorts of silts and clays and other unmentionables. Next on the list is sawdust and shavings. While acceptable to some people for indoor footing, I find them to be totally useless outside for several reasons. Both are far too absorbent and will turn to slush in a heavy rain. When dry they are very dusty, both get very slick if they get just a bit too wet. Bark mulch, tan bark and hog fuel are also waste products. They all fall into the same category and have the same problems. They decompose very rapidly because of the bark and sapwood content. They are very inconsistent materials. You may get some that is good and the next load will be all dust or have firewood size chunks floating around in it. These materials can also get slick.

Perhaps worst of all is manure. I have seen hundreds of arenas filled with stall cleanings. I have yet to see one that I would ride on. They are dusty, unsanitary and extremely slippery. They get even boggier than sawdust or shavings and unlike them, there is no middle ground when manure is nice to ride on. Manure is also a breeding ground for flies.

On the good list we have the most common footing of choice, sand. The next most common choice is a wood fiber mix. Third is stone dust and after that we have PVC mixed with sand and shredded rubber mixed with sand.

Each of these materials has its advantages and disadvantages. Sand, for instance, is a generic term that covers a myriad of materials, a great number of which are not terribly suitable for footing. My personal preference is a very clean, washed, screened medium concrete sand. It should be about two inches deep. Quarry sand is preferable to river sand because of the shape of the particles. Quarry sand is angular and river sand is round. The angular sand will support the horses better and can actually provide some bounce when properly watered.

Manufactured sand is actually a very fine crushed rock. As a result, it is not as hard as real sand and tends to break down faster. It performs like quarry sand. Another sand that I have had good results with is beach sand. A good medium beach sand is a favorite, if you can get it. It is extremely clean, almost dust free when new and is very uniform. When properly watered it is heaven to ride on. Like all sands, when dry it gets duney or cuppy. Other than the availability and some times the cost, the only disadvantage to beach sand I have found is that it will wash away a little faster than the others. Stone dust is a finer version of the base rock we used already and can be used as base material in some cases. I have seen arenas that are just stone dust (also called rock dust) six or seven inches deep. It becomes base and cushion at the same time. Some materials will set up for a base and other materials act like dirty sand and never get hard enough for a base, depending on the type of rock that they are made from.

On the surface, stone dust sounds like the ideal material, but it too has its drawbacks. First, if it will work for a base it will pack like cement and must be harrowed and even rototilled regularly to keep up a cushion. If it doesn’t pack well, it won’t work for a base but might make a good cushion if you don’t mind the dust. I have seen some materials that will ball up in horses’ feet so badly you might consider a jackhammer to remove it. If you can find a good compactible material that won’t ball up, have a good rototiller and a sprinkler system, then stone dust is a good choice. I have seen some very nice stone dust arenas.

The other choices of sand mixed with PVC or shredded rubber are used frequently enough that they deserve comment. PVC alone is reported to be slippery, but mix in a little sand and it rides quite nicely. To some, PVC has an offensive odor. It can get dusty and, because I have unanswered questions about PVC dust and lungs, I can’t recommend it.

Shredded rubber and sand, on the other hand, can produce a wonderful footing. Too much rubber will give a trampoline-like effect. Pure rubber as footing has some serious problems. It is way too bouncy, and stinks like old tires, because that is what it is. Because it is black it absorbs a tremendous amount of heat during the summer and becomes a veritable furnace. Other commercial footings now available include chunked up rubber, chunked up athletic shoes, and polymerized (plastic-coated) sand. For a serious look at all of the footing options out there, get in touch with a footing supplier and ask for samples. Cost varies widely, and so does availability.

There are lots of options for footing and everybody’s taste is different. Choose your footing wisely because you will have to live with it for a long time.

Keeping It Simple

Rule 6 is my favorite – KISS. (Keep It Simple, Stupid). The more complicated you make your arena design the more there is to go wrong, and the more there is to spend money on. One of my favorite complications is the time tested failure of putting French drains under the arena to drain the surface. The built-in failure is the idea that the drains will remove surface water. They won’t. They are designed for the removal of underground water.

My other favorite is the center box drain. A drain with a grate over it is placed in the center of an arena graded to the shape of a bowl. They drain well, but there are three little problems. One is that these drains have a nasty habit of clogging in the middle of the night in the worst storm of the season. It’s really fun to wade out into two feet of water and try to remember where the drain is to dig it out. The second problem is that horses have an instinctive fear of the Hole Troll that lives in these drains. They are also dangerous, because a horse could step into one of them.

KISS also means don’t put your arena where it will cost a lot just to build it. Put your arena where heavy equipment and trucks can get to it easily for construction and later for maintenance. What KISS really means is good thoughtful planning.

Rule 7: Everybody’s an “expert.” Get your advice from people who know. There are few people in this country who really know how to design an arena. Some grading and paving contractors are also horsemen and can do a good job. There are also contractors who have learned the hard way and continue to build a good arena. There are lots of contractors who will build a good arena if someone else designs it for them and supervises their work.

If the advice doesn’t sound simple and logical it probably isn’t. Use common sense. Beware of the “my cousin Elmo once did it this way” stories. If you get advice on an existing arena’s construction, check it out in both good weather and bad. Talk to those who use it and ride on it, if possible.

Rule 8: Building an arena is a series of compromises. There is no such thing as a perfect arena. It’s either too big or too small, too narrow or not long enough, too close to the barn or too far away. There is always something not perfect about the footing or drainage, especially if someone else designed or built it. Scapegoats are a dime a dozen when it comes to arenas. The arena is too dusty or too wet or just a tad slippery or the wrong color.

Take your time planning your arena. It isn’t something you want to have to do over. Ask yourself what you want, then ask yourself what you really need and can afford.

 
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