Figures for Fixes
     Creating top-notch arena footing takes planning, patience, and (no denying it) an investment.
     As a general guideline, a new arena with a sand cushion layer will cost $1 to $1.10 per square foot - if your site doesn't require extensive drainage work, more than a 1- to 2-foot elevation change, or installation of a stone sub-base (more on these details shortly). Renovating an existing arena can cost $3,000 to $10,000 (or more), depending on size and problems.
     Using footing other than (or in addition to) sand also raises costs. For instance, mixing an inch of crumb rubber into sand footing in an 80- by 160-foot ring adds $2900 to $3300; putting down a 3-inch hardwood-fiber cushion layer instead of sand in the same size ring adds $5000 or more. (Read more about footing materials below.)
     You may be able to lower your costs somewhat if you have access to - and can skillfully operate - the heavy machinery used in arena installation/repair, and if you're knowledgeable about such subjects as grading surfaces and designing and installing drainage. But arena construction is a specialized field; shortcuts and unskilled do-it-yourself efforts can easily end up costing you more. Quality footing is an investment that pays off in fewer injuries, more effective training, and longer arena life (ten years or more with good maintenance).

Step 1: The Right Site
     In deciding where to place your arena, here's what you need to consider.

• Drainage, drainage, drainage: The arena site that's the least fraught with complications (read: $$$) is the one that gets the least drainage water from other areas. From a drainage standpoint, a hilltop is ideal - but it may be too exposed and too windy for riding or teaching comfort. (Strong wind can also carry away the top layer of footing.) On sloping terrain, you can maximize drainage by placing your arena as near the top of the slope as possible.
       If your only location choice is in the pathway of draining water - for instance, at the base of a hill - you can still build, but you'll need to put swales (shallow ditches) on the uphill edge of the ring to guide water around it, French drains (gravel-filled ditches) around the rim, and maybe even drainage pipes under the arena. Extensive drainage work can add thousands of dollars to the cost.

• Stability of the sub-base - the layer beneath your arena's base: It has to stay put so the base can stay solid underfoot for your horse. (Base material installed on an unstable sub-base on an unstable sub-base may develop soft wet spots or potholes, or break up and begin mixing with the cushion layer.) Additionally, a solid base plus good drainage work around/under the arena enables footing to shed water within hours after heavy rain.

     An experienced arena builder can usually determine whether the subsoil at your planned site is of a type that can be compacted densely enough to form a stable sub-base. (If he has questions, he may recommend consulting a soils engineer.) Compaction takes place after the arena is "boxed": boundaries laid out, topsoil removed, subsoil graded. It's best done with heavy equipment such as a 20-ton vibratory roller. If a contractor builds your arena, that's what he'll use, along with tools to measure the degree of compaction. If you're doing the compacting yourself, you'll need to rent a roller - which will probably be smaller than 20 tons - and hire a soils engineer to test compaction.
     Things to watch out for: Remember that the sub-base needs to be crowned - sloped 1 degree from the center line to the sides - and pitched the same amount end to end. The crown and pitch, carried through to the base layer, enable water to drain off - which will enable you to ride more in wet weather.
     If your soil is too unstable to compact, or if you live in an area where deep freezing and thawing occur, you'll need a special stabilizing sub-base of 4 to 8 inches of "2A modified stone," compacted; like a soil sub-base, this stone sub-base needs to be pitched or crowned. Some arena builders recommend laying geotextile - heavy duty landscape cloth - between the stone sub-base and the compacted stone-dust base layer, to prevent stones from migrating upward. These extra steps mean extra costs, but they also ensure the arena's usability in most weather.
     Things to watch out for: Geotextile always goes beneath the compacted stone-dust base layer, not on top of it.

Step 2: A Sturdy Base
     The preferred material for your arena base is stone dust, also called screenings. Builders recommend limestone with bluestone (granite) as a second choice. Both contain a substantial amount of calcium; when the stone dust is watered and compacted, calcium causes individual stone particles to adhere into a solid layer. For a dressage arena, builders recommend a 6-inch base of stone dust, watered and compacted with a commercial roller to a depth of about 4 inches. For hunter/jumper or multi-purpose footing, which must withstand more concussion, the recommendation is 8 inches of stone dust watered and compacted to a 6-inch depth.
     Once the base is down, it must set up for anywhere from a few weeks to (in wet weather) several months. That's where the patience comes in. Then you can go on to…

Step 3: The Cushion Layer
     Your cushion layer needs to be 3 inches or less in depth; otherwise, your footing will be too deep. If you're installing a new cushion layer, experts advise, begin by laying about 1.5 inches of cushion material; add more gradually, as the footing settles and you get a feel for how your horse goes on it.
     Here are your materials choices:

•      Coarse-washed angulated concrete sand has several advantages: economy, availability, and satisfactory performance. Experts recommend sand with a "sieve analysis" of 33, indicating a limited amount of dusty fine particles. (Another way to designate the amount of "fines" is a "100#" or "100 Pass" number, which should be less than 5 percent.) The washing process removes organic matter, silt, and other dust-producing elements; if your supplier's sand contains too much fine matter, having it washed a second time improves the quality but increases the cost.
       Things to watch out for: Don't use beach or river sand. Their rounded grains slide past each other; angulated sand locks under pressure, providing traction. It's dense enough to keep hooves from pushing through to the base, and the minute pockets of air trapped in the spaces between grains absorb concussion. (Also avoid "man-made" sand created by crushing rocks; it breaks down to powdery fines very quickly.) If you use sand alone for a cushion layer, drag (see "Maintenance Magic" on page 80) after every day of use to maximize those shock-absorbing air spaces.
       You can mix several substances with sand for added spring, resilience, and in some cases - all-weather capability.
•      Crumb Rubber increases sand's cushioning quality and counteracts its tendency to pack down. Dark-colored rubber particles don't absorb water but do absorb solar warmth, so they help prevent freezing (and speed thawing). Because adding material is easier than removing (and storing) excess if the footing is too deep, builders recommend starting cautiously with about 1.5 inches of angulated sand and 1 inch of crumb rubber, adding more rubber gradually (if needed) until the footing achieves the desired amount of bounce.
       Things to watch out for: Crumb rubber comes from recycled tires, so choose a product marketed for equine arena use and guaranteed free of metal fragments (from steel-belted radials).
•      Wood products (chips, sawdust, and shavings) are inexpensive, add bounce, and absorb moisture. Add about 1 inch to 1.5 to 2 inches of sand.
       Things to watch out for: Wood breaks down quickly, creating dust if not moistened regularly. Use only new products; shavings recycled from stall cleanings cause odor and fly problems.
       Besides sand and sand mixes, other materials can be used for the cushion layer:
•      Uncompacted stone dust, used over your compacted stone-dust base, gives better traction than sand because its particles tend to "lock" under pressure - a plus for jumping and tight turns. It drains more quickly than sand, so it's more usable in wet weather. However, its tendency to pack down means it requires more frequent maintenance, and it needs more watering in dry conditions. Slightly pricier than sand, stone dust can be used alone or mixed with any of the footing products added to sand for increased springiness.
•      Processed hardwood fiber (commonly seen under playground equipment) forms a resilient mat that works better for riding on the flat than over fences. It's more expensive than sand or stone dust; as it breaks down with use, more fiber must be added. Regular "misting" controls dust.

Improving What's There
Suppose you already have an arena. Here are the problems you might be seeing and the strategies to correct them.
     Cushion-layer problem: a "dead," dusty, and/or compacted sand cushion layer. Even with good maintenance, traffic breaks down sand particles; as they become smaller, they pack together instead of trapping air, and the tiniest grains billow up as dust. Loss of cushioning effect means concussion for your horse's joints; dust affects his respiratory tract (and yours). Adding crumb rubber won't improve matters; the worn-out sand grains are too small to mix properly with the rubber, and the added material can make the cushion layer too deep. Watering temporarily quells dust but contributes to packing down.
     Solution: Remove the old sand and replace with top-quality new sand. (Stripping out old footing also gives you an opportunity to check the base for problems and repair as needed; see below.) If you want to mix crumb rubber or some other product into the new sand, adjust the amount accordingly. As when installing footing in a new arena, start with less than you think you'll need; add more a little at a time.
     Base-layer problems include irregularities of several sorts. To fix them, you can repair the base, add new stone dust, and then water and compact as if starting from scratch. As you repair, check for and correct pitch or crown as needed. Here are the specifics.

•      Highs and lows or ruts: Scrape away the base until it's level. Remove at least an inch of base to get down beyond where any sand has mixed with it - because screenings mixed with sand won't compact. Now water and re-compact; then measure. If the base is now less than 4 inches deep, add new screenings and water and compact again until it's 4 inches.      Things to watch out for: Builders recommend using a bulldozer, rather than a tractor or front-end loader, to scrape away old base smoothly and accurately.
•      Soft spots may first show up as areas that are slow to dry out after rain or watering. To correct, dig out the spot to a depth where you encounter firm material. Fill the bottom of the hole with 2B modified stone; water and compact it; then cover with a layer of geotextile. Fill the remainder of the hole with stone dust; water and compact until the spot is flush with the surrounding base. This technique creates a bridge over the soft spot to surrounding areas of solid sub-base and base.
•      Potholes are hollows where the base has subsided or broken up. Dig at least a foot beyond the sides of the pothole and deep enough to reach solid material; fill and compact as for soft spots.

Planning Checklist
     Tailor the specifics of your arena to what will be happening there.

•      Your sport(s): Primarily hunter/jumper, dressage, or both? Hunter/jumper sports require both a thicker base and a "grabbier" cushion than work on the flat Because of the traction required for turns, takeoffs, and landings.
•      Intensity of use: Just yourself? Two or three people daily? All-day group lessons? Heavier use increases maintenance needs; for advice, see page 81.
•      Size: For dressage, you'll probably want at least 80 by 160 feet; that's slightly larger than the 65 by 131 feet or 20 by 40 meters, required for the official 'small' arena. For multipurpose use or for over-fences sports, go for at least 100 by 200 feet. For either, you'll want additional space if more than two riders will be in the arena at one time.
•      Budget: Add up what you'll have to spend for what you want; prior research (including getting estimates from a couple of experienced arena builders) helps you plan. Variables affecting the cost of a new arena include your terrain and soil type, your site options, whether construction materials will have to be shipped from a distance, and whether you can do some of the work yourself. Raise your projected-cost total a little to allow for unexpected problems, not covered by your contract, that require extra work. Then compare your projected costs with what you think you can/should spend - and if the two don't match, look for where you can trim costs without cutting quality.

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