Designing an arena

The choice of structure and the composition of an arena or a ring depend mainly on the use you are going to make of it (what discipline and how often).

• Training facilities should have a comfortable footing so that the horse can give its all while protecting its musculoskeletal system.
• Competitions on the other hand, require a footing that encourages performance: show jumping competitions require a responsive footing with rebound, polo matches require a very regular and closely mown surface (for grass footings) and racing requires a loose surface...

In all cases, however, it is important to install a durable surface, which is easy to maintain and can be used for as much of the year as possible (pay particular attention to sensitivity to frost).

Depending on the desired result and the discipline in question, different building techniques apply. The main types of construction are as follows.

Surface on an enclosed structure with a sand surface

On a non-draining surface, any excess water is evacuated from above through the presence of slopes. These arenas are mainly used for show-jumping competitions because as they are soaked in water, they are highly “responsive” and remain fairly firm.

Draining surface on an open structure with a sand surface

On a draining surface, any excess water is evacuated by percolation through the top layer, and then joins a drainage layer followed by a network of drains directed towards an outlet. Sand is often reinforced with fibres or geotextile chips. These surfaces are often fairly flexible. More comfortable and gentler on the musculoskeletal system (including during falls!), they are widely used for dressage and for working with horses on a daily basis in general.

“Sub-irrigated” sand arena

An arena with a perfectly flat and draining surface is installed upon a totally impermeable layer. By adopting the principle of communicating vessels, the water level on the top layer of the arena is managed through a connected “well”. By varying the quantity of water in the surface of the arena, the texture of the soil also varies: the more humidity in the surface, the more cohesive it is.

In practical terms, creating this type of equipment is a fairly technical undertaking, but does give excellent results. In particular, it enables the level of water on the top layer to be regulated fairly precisely, thereby making it possible also to regulate the firmness of the surface. Automating the process can also guarantee a perfectly consistent surface quality throughout the day, whether it be dry or raining heavily.

“No water” surfaces

The idea is to replace the water with a binder that does not evaporate. In addition, various patented processes use mixtures of Vaseline and/or waxes. These manufacturing processes make it possible to entirely or almost entirely eliminate watering and make the treated surfaces practically insensitive to frost.

The success of such projects depends firstly on preparing the sand/binder mixture and, depending on the manufacturer, fibres, chips, aggregates, etc., the role of which is to improve the mechanical qualities (load bearing capacity, cohesion, shock absorption and resilience) of the mixture. These mixtures are exclusively prepared on a large scale by specialised companies.

Generally speaking, the quality of the surface will depend on the use of materials according to the discipline and the daily maintenance (occasional watering, collection of droppings, grading the surface, etc.).

Grass surfaces

A noble surface par excellence, grass surfaces are highly sought-after when it comes to organising competitions. The deep roots of the grass and surface drainage are the parameters to be checked regularly and to be monitored throughout the installation and maintenance of the arena in order to obtain a surface that offers the mechanical qualities sought after in competition, and to ensure that these qualities last throughout the classes.

Foundations

The entire surface area of the arena is excavated, and the topsoil is set aside.

Depending on the nature of the materials “revealed” after stripping the topsoil, several actions can be carried out:

• The natural uncovered soil can be compacted;
• The soil can be chemically treated with lime and/or cement and compacted;
• In all other cases, foundations from compacted materials must be installed, with a thickness depending on the role of the sub-soil but at least 20 cm thick.

The profile of the foundations will determine the finished profile of the arena. The definitive slopes of the arena are therefore created depending on the constraints of the terrain, aiming for the shortest slopes possible to optimise the speed of evacuation of any excess water. The “diamond” or “dome” profile is therefore preferable to a single slope which is necessarily longer and more vulnerable to erosion.

Drainage

In this type of configuration, drainage under the arena would be useless. It is, however, essential to recover run-off water along the edge of the arena in a gutter, ditch, evacuation valley or drainage trench.

Intermediate layer

In order to create an anti-contaminating interface between the foundation material and the top layer, and to ensure the quality of the foundation, it is useful to use an intermediate layer. The most widely used material is a crushed material with a granulometry of 0/4 or 0/5, fairly rich in fine particles, with a depth of 5cm. On the surface, slopes are kept at 1 to 1.5% (see diagram above).

Top layer

Ideally, this should be composed of industrial silica sand. More precisely, it should consist of at least 95% SiO2 and 0/D granulometry with D<200 µm.

Depending on the geographical location of the site, this solution can be expensive, given the small number of extraction sites and the transport costs involved. It should be noted that it is possible to reinforce or adjust the top layer by adding geotextile chips or synthetic fibres. The effectiveness of this solution can only be guaranteed by using specialised companies with expertise in this field. Thickness: 12 to 15 cm.

Some very fine, rounded sands may also be suitable, but production of these is not standardised, so it is difficult to say how they will behave depending on their origin. Thickness: 15 cm.

Foundations

The entire surface area of the arena is excavated, and the topsoil is set aside.

Depending on the nature of the materials “revealed” after stripping the topsoil, several actions can be carried out:

• The natural uncovered soil can be compacted;
• The soil can be chemically treated with lime and/or cement and compacted;
• In all other cases, foundations from compacted materials must be installed, with a thickness depending on the role of the sub-soil but at least 20 cm thick.
• The careful creation of gentle slopes can direct run-off water from the surface towards the arena’s drainage system.

Drainage

Unless the sub-soil naturally provides sufficient drainage, it will be necessary to install a drainage network. The dimensions of this network will vary depending on the region and local rainfall.

In all cases, it is advised to line the edges and base of the drainage trench with geotextile fabric. This trench should ideally be lined with highly draining material: 4/6 gravel for example.

Intermediate layer

An intermediate layer is strongly recommended and can fulfil a number of roles depending on the materials used:

• A crushed material (often reconstituted) can be used. It will have a grain size of 0/20 or 0/31.5 with a relatively small percentage of fine particles (less than 5%). Ideally, this is a material suitable for use as a draining foundation layer for a large playground in accordance with the NF P 90 112 standard and characterised as such. The layer thus created will be draining and filtering. Thickness: 15 cm
• Plastic gravels or sands can also be used, made from recycled electrical cable sheaths or rubber. This solution requires the creation of an additional drainage and filtering intermediate layer to ensure a long-lasting performance. It is strongly recommended to entrust the installation of this type of surface to a company specialised in the creation of equestrian surfaces.

Top layer

This is ideally composed of industrial silica sand (SiO2 > 95%) with a 0/D grain size, and D of around 350 to 400µm. Care must be taken to check the permeability of the sand used, which must comply with the limits mentioned below.

In order to obtain the desired texture, especially in equestrian competitions, this sand is reinforced with fibres. This must be very carefully installed, preferably by a specialised company. Many types of sands can be used for instruction or training, even at a high level.

For training purposes in particular, crushed/rolled sand mixtures with a grain size of 0/1 (0/2 maximum) in proportions varying between 60%–40% and 80%–20% depending on the desired degree of firmness can be used. As crushed sand adds firmness, depending on its composition (proportion of fine particles < 80 µm), it is advisable to proceed by trial and error to obtain a result that meets expectations.

Some very finely rolled sands may also be suitable, but as production of these is not standardised, it is difficult to say how they will behave depending on their origin. As before, it is essential to test the permeability of these sands before the equipment is built.

Except in special cases (unsuitable profile, marshy ground, etc.), it is advisable not to disturb the structure of the soil in place. A simple re-seeding or drainage is usually sufficient to build a quality arena for extensive use. In the case of terrains intended for intense competition (in terms of level and/or number of participants), a specialised project manager should be consulted to provide a technical solution including:

• Reinforced drainage to ensure that events can be held even in heavy rainfall;
• A complex substrate layer, i.e., the soil texture is modified, in particular by adding significant amounts of sand which increases permeability but makes the soil more sensitive to drought and more dependent on fertilisation;
• An integrated watering system that optimises grass growth between competitions and adjusts the soil texture during competitions.

Foundations

The entire surface area of the arena is excavated, and the topsoil is set aside. Depending on the nature of the materials “revealed” after stripping the topsoil, several actions can be carried out:

• The natural uncovered soil can be compacted;
• The soil can be chemically treated with lime and/or cement and compacted;
• In all other cases, foundations from compacted materials must be installed, with a thickness depending on the role of the sub-soil but at least 20 cm thick.

Drainage

In all cases, it is advised to line the edges and base of the drainage trench with geotextile fabric. This trench should ideally be lined with highly draining material: 4/6 gravel for example.

Intermediate layer

Although not compulsory, this layer can play a useful drainage role depending on the quality of the natural soil.

• A crushed draining material with a grain size of 0/20 or 0/31.5 and a relatively small percentage of fine particles (less than 5%) can be used. Ideally this is a material suitable for use as a draining foundation layer for a large sports area in accordance with the NF P 90 112 standard and characterised as such. The layer thus created will be draining and filtering. Thickness: 15 cm
• Pozzolan-style materials can also be used, which have particularly good permeability, water retention, stability and absorption qualities.

Top layer

It is difficult to make general statements on the work involved, soil improvers and sowing to be used, as the properties of top soils vary by region. In general, a texture with a high proportion of sand (> 60% or even 70%) and a low percentage of clay (< 8%) is required.

For surfaces intended for intensive use, it is essential to contact a specialist and carry out soil analyses to adapt the construction and the general maintenance programme to the characteristics and properties of the soil.

The creation of slight slopes of 1 to 1.5% is however essential to allow rapid drainage of rainwater in the event of heavy rainfall.

Surface drainage

In order to improve the drainage of a grass arena, sand is laid to improve the texture, but surface drainage can also be used. The principle is to create “drainage channels” that connect the surface directly to the drainage network or to the drainage layer, depending on the construction of the terrain.

Seepage slits (when the top soil is removed to fill the slit with draining gravel) or drainage trenches (top soil is removed to be replaced by a trench of draining gravel) are made perpendicular to the drainage network and overlap it by a few cm to ensure the continuity of the network up to the outlet. It is easy to understand that arenas equipped with such systems are drier and require greater monitoring.

Regardless of the technical choices made when installing a sand surface, good maintenance is essential:

• Watering using a high-performance automatic system is highly recommended.
• It is essential to remove dung on a daily basis in order not to alter the structure of the surface and its drainage qualities. For the same reasons, it is important to be careful when planting trees near arenas and to ensure that any fallen leaves are collected.
• Regular mechanical maintenance, harrowing and levelling of turning areas, the lead-up to and after jumps and regularly moving them, and levelling the “tracks” is essential for the comfort of horses and riders and the durability of the surfaces. This depends of course on the frequency and intensity of use.
• Finally, an annual reprofiling must also be scheduled to maintain the drainage capacity of each type of arena.

Grass is a living surface and is therefore constantly changing. Maintaining it is crucial to ensure the quality of the track. The list of equipment and maintenance operations are too long to detail here, however, the main ones are as follows:

• Mowing: this is the essential operation. Depending on how frequently it takes place, the grass can be longer, ensuring the density of the vegetation cover. Blades must be sharpened and mowing waste collected.
• Aeration, decompacting: this operation aims to bring air into the soil to develop deep rooting. Roots cannot grow in compacted and asphyxiated soil.
• Grooming: this involves removing moss and the layer of decomposing organic waste (grass clippings, roots, dead leaves, dung) which makes up a damp layer on the surface of the soil in which roots tend to develop and which suffocates the soil.
• Sand laying ... Soil enrichers

And of course, regular watering is often indispensable and is set out in the information sheet on watering equestrian training areas.

Sand surface

Other than in very exceptional circumstances, to avoid unpleasant dust for riders and horses, and above all to ensure a cohesive top layer, regular watering is absolutely essential.

Several types of equipment are possible depending on the intensity of use of the exercise area and the water requirements of the terrain. Generally speaking, fixed water guns (or turbines) give great results in terms of performance and ease of use.

To ensure a sand arena is well watered, care should thus be taken to:

• Ensure a good overlap between the watering sectors, so that even in windy conditions the whole surface is watered;
• Have a water reserve (recuperation tank, reservoir or network flow/pressure), which is essential given the flow rates required to ensure sufficient range for the guns and therefore a good overlap of the watering sectors (pumping from a well is unfeasible);
• Install a timer for night-time watering to avoid any the system starting in an untimely and dangerous way while horses are present.

Grass surfaces

Watering is essential for the plant to take root properly and is necessary to obtain a certain flexibility and deformability. It must be regular and controlled.

The advice in the previous paragraph also applies to grass surfaces. In addition, more even watering should be sought so that the turf grows evenly. The use of a specialist is essential. See also the fact sheet on watering equestrian training areas.

Teaching/club

No imposed dimensions other than in the case of regular dressage (see below). However, usage shows that the minimum requirement is a 20 m x 40 m arena (20m x 20 m in the case of a pony club).

Dressage

Rectangle of 20 m x 60 m, on a flexible surface.

Show jumping

Competitive show-jumping training requires a minimum area of 2,500 m² in order to be able to familiarise oneself with the different sequences and jump lines and combinations in good conditions.

Compétition

For the organisation of competitions, a surface area of 3,200 m² (40 x 80 m), approximately rectangular, is a minimum size. If a larger surface area is available, the shape of the terrain and its gradient can be varied for grass surfaces. However, slopes greater than 5% should be avoided, as they limit the course configurations and generate jumps with excessively steep descents. Recommended dimensions: from 4,000 to 10,000 m² or even more.

Warm-ups paddocks

For warm-ups, a smaller paddock (20 m x 40 minimum) should be available.

50 m in length is a more comfortable limit for warming up over jumps, especially when the paddock is used more often or when young horses are less experienced and less manageable.

30 m wide allows for the comfortable organisation of three fences over the width of the arena.

Large warm-up arenas are a guarantee of comfort and safety that riders appreciate. Generally speaking, one should not lose sight of the fact that riders spend 90% of their time in the warm-up area and that as such, this area is used much more intensively than the show ring. Ideally, the warm-up area will be built with the same kind of surface as the show ring.

Racing training track

No imposed length, minimum recommended width: 3 m.
Top layer generally quite deep, on a draining structure.

Driving

Dressage training area: 40 m x 100 m.
Manageability: 70 m x 120 m.

Trotting training track

No imposed length, minimum recommended width 3 m, raised turns.
Top layer of crushed sand 0/2 on an enclosed structure.

Polo

Practice arena: 160 m x 80 m
Match field: flat grass field mowed short, length 230 to 275 m, width 145 m minimum if surrounded by boards.

Horse Ball

Field: 25 m x 65 m + 3 to 5 m safety zones on the sides.