HOW TO CONSTRUCT AN ARENA
Arenas come in many shapes and sizes, but whether you want the standard 20x60m or something more customised, there is one universal truth; building a safe, workable arena takes planning, effort, and investment.
First up, you need to check with your local council/municipality/authority as to whether planning permission is required. Next, figure out where the water will go from your draining channels and whether this might create a problem for your neighbours or the local area.
If you have permission, or don’t need permission, and you’re not going to flood anything you shouldn’t, you’re good to go.
Size and Location
While you can never have an arena that’s too big, you can certainly have one that’s too small, so make sure it’s fit for purpose from the start.
Standard sizes:
40m x 20m - novice dressage
60m x 20m - advanced dressage
Minimum 25 metres wide – show jumping
The ideal location for your arena is a well-drained area that requires minimal soil movement. Avoid low-level areas where drainage could be an issue.
Once you have chosen the site you want, the length of the arena should run north to south for maximum sun coverage throughout the day. This allows for more riding time, and drying time following wet weather. Try to avoid exposed areas, or invest in a windbreak, to prevent your valuable arena topping from being blown away.
Site Preparation
Give contractors room for installation by making out a boundary one metre larger than the size of the arena required (40m x 20m arena would require 42m x 22m).
Install four corner pegs and run a string line between them. Check that it is square by measuring the diagonals – if they are identical, it’s square.
To keep costs down, excavation should be kept to a minimum. Remove the topsoil and vegetation to expose the subsoil, which could be anything from 25mm to 300mm. Never build on topsoil as the organic matter is prone to waterlogging and has poor load-bearing.
Level the area with appropriate falls towards your drainage area, ideally using a dual grade laser level.
Drainage Preparation
One of the most important tasks when building your dream arena is drainage preparation.
Unless you have exceptional free-draining soil, a ‘herringbone pattern’ land drainage system is recommended to carry away surface water. These drainage channels should be dug before the base membrane is laid and the land drainage is installed.
Next steps:
Dig a central channel to take the 100mm diameter central collecting pipe (spine). This should run down the centre of the arena, vertical or diagonally, towards your discharge location, which might be a ditch, pond, stream or soak–away. This channel should be 30cm wide and have a varying depth (minimum 40cm). Invest in larger spine pipes if drainage is an issue;
The spur trench channels should be dug off the spine at 45 degrees at five-metre intervals. The depth at which the drainage channels should be installed will be dictated to by the discharge point. Start at the highest point and keep as shallow as possible while retaining a fall. The spine pipe should be lower than the spurs.
To retain a well-drained perimeter, which will also protect timber posts, a perimeter trench outside the arena is recommended.
Installing Drainage and the Base Membrane
Once the excavation is done and the channels are dug, the whole arena should be covered in a strong, woven geotextile membrane to prevent existing subsoil and the new sub-base stone from mixing. This will allow water to penetrate through to the drainage channels, which should also be lined. Lining the trenches will further reduce your drainage channels from silting or blocking up from the surrounding sub-soil.
Joins in the membrane should overlap by a minimum of 30cm then sealed using a suitable strong tape, glue or heat sealant. A bottom layer of washed 20-40mm shingle should then be added prior to the drainage pipe going in.
To make life easier, try to connect the pipework in a ‘herringbone pattern’ above ground, then lower it into the channels. Next, install the 100mm diameter central collecting pipe (spine), cutting the spurs in as you go.
The 80mm land drainage spurs should be laid at 45-degree angles off the main spine.
Once all the pipes have been installed, fill the trenches with the remaining shingle so the site becomes level again.
Installing the Stone Drainage Sub-Base
The sub-base layer is the foundation of your arena and it will also ensure that your drainage system copes with heavy rainfall.
A standard 40m x 20m arena at a depth of 150mm would require approximately 220 tonnes of stone. A 60m x 20m arena would need 330 tonnes.
Create a 150mm drainage base layer using 40mm-75mm quality clean, washed, frost resistant angular stone. Avoid any stone that has not been washed or contains fine dust or soil as these will end up clogging your drainage.
A 250mm uncompressed surface will compress down to a working surface of approximately 150mm. The sub-base layer should be compacted using a vibrating roller and laser level.
The sub-base drainage layer should exceed the arena size by approximately 50cm, to allow for water run-off beyond your arena, especially if installing a perimeter drainage channel.
Now to the Fencing
The most popular design for arena fencing is a three-rail sawn post and rail design with kick/ retaining boards at the base.
Firstly, install corner posts by concreting in and measuring as you go to make sure they are in the correct location. Intermediate posts should be spaced every 1.8m if using 3.6m rails or every 2m if using 4m rails.
If concreting, a concrete sleeve, not boot, is recommended because a sleeve will stop the rot by allowing moisture to escape. Rails should be nailed or screwed to the inside of the posts to provide a softer internal line which will reduce the potential of injury to both horse and rider. Retaining/kick boards, which help retain the top surface, should also be screwed or nailed to the internal face of the posts.
Top Non-Woven Membrane Installation
Non-woven membranes are spun-bonded fibres of polypropylene and needle punched for water permeability. They prevent the sub-base stone from migrating to the surface; they filter surface water efficiently and quickly, whilst retaining topping; they prevent the upper surface from migrating downwards, clogging the drainage sub base; they eliminate movement when horse’s hooves apply pressure on the surface; and they rip if hooves make contact, thereby reducing the possibility of injury which may occur if the main topping surface is not maintained.
If a fine Silica sand topping is used, a premium non-woven for the top layer is recommended to prevent finer particles of sand from filtering through the drainage sub base layer.
When installing, it is crucial to make sure there is adequate overlapping and it ought to be glued or taped to prevent any lifting. The slightest gap or hole will eventually allow the top surface through and lift your membrane.
Make sure you have adequate overlap over the retaining boards. Once the top surface has been laid these can be trimmed back.
Surface Installation
Whichever type of topping you choose, consideration should be given to the depth required, this will be governed by the material chosen.
Remember, you need a suitable depth so that you do not expose the top membrane. Surface choices include:
Wood chip and fibre chip. Good for indoor and outdoor arenas, gallops, lunge pens, turn-out paddocks and horse-walkers. However, the lifespan is relatively short (between four and 10 years). It can also become slippery when it dries out, so it needs regular watering.
Rubber chips. Good for outdoor arenas, particularly jumping, as horses are less likely to skid or get concussion injuries. A rubber-based surface has serious longevity and requires less maintenance than other toppings. Rubber doesn’t freeze and it’s dust-free, but it also needs a base, such as silica sand.
Sand and sand mixes. Good for galloping, many all-weather racetracks are sand-based. Sand was once very popular, but it gradually gets finer with use, becoming progressively deeper. If your surface is unwaxed, it will need to be watered during dry weather for optimum performance. It should last five years or more.
Maintaining Your Arena
An arena is a lifelong commitment that will need regular maintenance, from removing weeds before they penetrate membrane layers, regular raking to maintaining a level surface in order to stop the topping from migrating to the edge or the centre. Surfaces will also need topping up occasionally.
This article is adapted (with kind permission) from a blog post written by McVeigh Parker: Farming and Fencing Specialists. To read the full post, and for details of their products, visit the McVeigh Parker website by clicking here.
