As I prepare to build my own round pen, I thought I would share this fantastic article detailing how to build a winning arena (round pen).

Originally printed on the website.

Waterlogged fields, poached paddocks and mud-spattered horses have been a feature of the past week as stormy weather moved across the country. Of course, Irish weather being what it is, we don’t actually need a storm to have those conditions prevail throughout much of winter, but it’s at times like this that thoughts turn to building better facilities.

How much easier life would be if you had a purpose-built arena to exercise the horses? To be able to turn them out for a few hours, even on very wet days, without the associated risks of mud rash and poaching?

The current slump in the residential housing market has seen a notable slowdown in the building trade, so contractors who would previously have been preoccupied with large housing estates may now be eager for jobs such as arenas and gallops. Certainly, the number of farm building contractors has risen in direct proportion to the decline in residential building.

There are also a number of companies in the industry who specialise in equestrian facilities and have a wealth of experience behind them. Equestrian Surfaces Ireland, based in Nurney, Co Kildare, have provided the surfaces for a number of well-known arenas across the country, including the RDS, Kill International equestrian centre, Coilog eventing, Marlton dressage and Ballinrobe races.

Although you may think building an arena at home is as simple as railing off a level corner of a paddock and chucking in enough sand to make it look professional, the reality is different.

The standard size of an arena is 20m x 40m and the most common mistakes people make when building an arena is to provide inadequate drainage and skimp on material.

According to Equestrian Surfaces, the first step in building an outdoor arena is to choose your site carefully. You might want a sheltered area, for example next to a line of trees, but this will give you problems in autumn when leaves start to drop.

How near is the area to a ditch for drains to run to, or an existing drain where drainage can be taken to? How level is the site? The more level it is, the lower the leveling cost. And how good is the access to the arena?

Once you have chosen your site, the next step is to strip the top soil off and level the site with a laser level. Most ground has only about six inches of top soil, so if your site is on level ground there is no need for major excavation.

Next, dig drainage trenches approximately 1ft deep by 1ft wide, every 5m across the arena, running out to a larger perimeter drain. This larger drain leads to an existing, or purpose-built, soak pit or ditch.

Lay 80mm or 100mm diameter drainage pipes inside the arena trenches and fill to the surface with 20mm pea gravel. If the ground is sandy or contains silt, the pipes must be wrapped in a membrane to stop the small particles blocking the drain. The perimeter drainage pipes are larger, ranging from 100mm to 150mm, depending on the size of the arena.

The next step is to lay the lower geotextile membrane across the entire arena, overlapping by about 0.25m.

Now the fencing must be put in place. The recommended fencing for an arena is a post and three-rail fence made of creosote-treated timber, concreted in, to stop the posts waving in years to come.

Once all posts are in place, the kicker boards and rails can be put on. The kicker boards, also called retaining boards, are designed to contain the surface of the arena. With the fencing in place, the next step is to add the drainage stone. This is a five inch layer of clean angular crushed stone. The stone should be 3-4inches in diameter with no smaller stone or dust. This stone is compacted with a vibrating roller to level it off.

An upper membrane is layered over the levelled stone and the final step is to add your choice of riding surface.

Dr Tim Butler, sports turf scientist and agronomist, says your choice of riding surface is critical to the success of the arena.

Having lectured all over the world on the science behind sports turf, Dr Butler has set up his own business and website, which is devoted to giving advice on surfaces for horses.

He warns that when using sand for an arena or gallop, there is a certain type of sand that is required. “Your local builders’ sand will not be suitable because it has the wrong particle size distribution,” he explains.

“The size of the sand particles directly influences the quality and safety of your riding surface. If there are too many coarse particles or too many fine particles, you will have lots of problems,” he says.

“Too many coarse particles will be very abrasive to the horses’ feet and the sand shape is very angular, so the surface does not knit together and it will remain very open. On the other hand, if you have too many fine particles the surface will compact and become like a cement block in summer. As well as that, smaller particles can block your drainage lines,” he adds.

“Wexford sand is very popular as a riding surface, but there may be other sand quarries in the country that have the same particle size distribution,” says Dr Butler. “But I can test the sand in any quarry to see if it would be suitable. Equally, you can mix different sands to create the mixture required.”

“At a cost of around €30/t including VAT for Wexford sand, the biggest factor is haulage costs, so if there was suitable sand closer to home, you could save €6 or €7/t.” With up to 100t of sand required for an arena, that could save you €600-€700.

However, you can use more than just sand for your riding surface, with everything from rubber chips, carpet fibres and wax added to the mix in arenas.

The idea behind these extras is to add life to the sand by giving it more bounce, prevent compaction and to help prevent the surface freezing in winter frosts. The additional materials can also make the surface easier on the horses’ legs, preventing concussion and other injuries.

Adding rubber to the mix is designed to give ‘life’ to sand, which can sometimes feel very dead to ride on. The rubber chips are made from recycled tyres and can be added in varying amounts to the sand, depending on how much bounce is needed.

Recycled carpet fibres are also used to give a cushioning effect to the sand and reduce compaction. However, the disadvantage of carpet fibres is that over time they will rot.

“Carpet fibres are difficult to source and are very expensive, so you should be cautious about using them,” warns Dr Butler. “But if you have a proper management programme in place to add fibres regularly and rotovate them through the sand, they are a very good way of improving the riding surface.”

Wax can also be added to sand to help the sand particles to stay together and is particularly beneficial during very wet and very dry weather.

“The one problem I see with wax is that it sticks to horses legs and needs to be power-hosed off after they ride on it,” says the surface expert. “So it may be quite awkward in a stud farm situation.”

However, wax is popular at racecourses because it means the surface can be ridden on all year round and it has been used in the tracks at Wolverhampton, Kempton Park, Newmarket and Epsom.

“The first thing I would advise for anyone who is building a gallop or arena, is to do a site and soil analysis so that we can understand what is going on underneath the surface, whether it will need artificial drainage or not,” he explains.

“Secondly, I always ask the client what are their expectations of the surface: are they looking for a Rolls Royce surface or simply a good, ordinary surface that will do the job and not cost the earth,” he says.

Trade secrets: Adding rubber, carpet fibre or wax to the sand arena could help prevent concussion to the horses’ limbs when jumping.
Caitriona Murphy