Roots are the earth’s natural way of stabilizing soil as it is exposed to harsh elements day after day. Whether belonging to grass, shrubs, or trees, roots extend into the ground like fingers, keeping the soil contained during even the harshest rainfall.
In the horse arena however, this is not possible.
Manicured and cultivated to be in the best condition for riding, horse arenas have layers upon layers of rock, sand, and organic matter with nothing to hold it in place. This creates drainage and soil displacement when weather like heavy rain arises.
Over the years, equestrians have found many solutions to this problem with varying degrees of success– geogrids and geocells being among the most promising. Below is a quick look at how geo-technology works and how it can help fortify the base of your arena.
Horse Arena Base Material: Building the Sub-Base
The base of your arena withstands a majority of your equestrian activities. As such, choosing the right sub-base and base materials for your needs is an integral part of your arena’s longevity.
First, you must “box out” your arena by digging six or more inches into the soil. This is done in such a manner where the center of the arena is slightly higher than the edges. This dome usually follows a 1-2% slope and allows for better control and drainage of puddles occuring in the main area of your arena.
Once this foundation is established, an aggregate stone layer is added. The type of stone most commonly used for this layer is sharp and angular, thus allowing for more drainage and circulation promoted by the pronounced gaps between the stones. While the depth varies, this layer is normally between two and three inches thick.
Having now built your sub-base, your arena is ready for base construction. Before adding the base layers however, it is likely you will utilize some geo-technology to increase your arena lifespan and further aid in drainage, layer separation, and ultimately, support.
Geo-Cell Technology: How it Works
When soil, sand, or stone is exposed to the elements, the particles will shift and move without proper reinforcement. Geo-cell technology, either in the form of geogrid or geocells, reintroduces this support and cultivates a host of benefits.
Geocells are rigid 3-dimensional plastic grids. Geocells provide superior vertical and lateral support. The pocket-like structure of these cells along with the perforations, provides better drainage, while keeping your substrate in place. This is particularly helpful if you are worried about your base layers shifting under the impact of heavy traffic or causing deep spots from regular weather exposure. Geocells work best when placed in the sub-base layer, helping contain the aggregate stone from potentially migrating from its position and thus reinforcing the underside of your arena’s base.
For more information on geocells, see this article.
Final Touch: Base Layers and Footing
Once you have reinforced your sub-base, the base layer and footing can be added.
While variations exist between indoor and outdoor arenas, generally a compacted layer of quarter minus two inches deep on top of the geo-cell, serves as a base material. The important factor in choosing the material choice is that it must be readily compressed using machine force. For this reason, materials such as quarter minus or decomposed granite are common and effective. Once spread and covering the geo-cell, a heavy roller to compact the base footing is recommended.
Once the base layer is placed and compacted, footing material can be added. This top layer is the opposite of the base as it is meant to be loose and non compacted, often composed in large part by a thin layer of sand and a footing additive such as FoamFooting™.
While footing layers must be chosen in accordance with the type of traffic, activities, and climate exposure of the arena. An arena surface used in an outdoor, light-traffic setting will vary wildly from an arena surface that is outdoors, uncovered, and/or subject to heavy amounts of traffic and equestrian activities.
For a more in-depth look at arena footing, check here.
The Indoor Arena: A Living Organism
Even with the best care, most arenas will need to be entirely overhauled within five to ten years. Arenas that have installed geo-cell bases, have been known to enjoy 3-4x the lifespan of those without, requiring only the top sand layers to go through refreshing over time.
The arena is a living organism and no single recipe will unlock the secret to a perfect surface. In the course of an arena’s life, organic matter will be mixed in with the footing, prolonged exposure to the elements will eventually wear at your drainage, and daily traffic will continue to shift the various layers of substrate.
Nevertheless, adding support such as geocells objectively benefits any arena. By promoting faster and more effective drainage, geocells help reduce moisture and puddling after the rain. Fewer puddles entends the longevity of the base, footing, and finally, allows the equestrian to return to riding sooner rather than later.