Support for tougher turf

Turf reinforcements offer a solution for strengthening areas subject to heavy wear, says Maureen Keepin.

Floods throughout the country last year demonstrated the vital need to retain grass areas, which act as a natural soakaway. Hard landscaping may be easy to maintain but the downside is that it is not permeable and contributes to worsening flood statistics.

The problem? You have turf areas subject to heavy wear and the grass is prone to become muddy and rutted. The solution? Turf reinforcement to protect the grass and offer full natural drainage.

Applications for using reinforcements for lighter use generally include grassed overspill car parks, utility access areas, emergency access routes, wheelchair access routes, golf buggy paths, heavily pedestrianised grass paths and nature trail paths.

Heavier-grade materials offer greater load-bearing capabilities and are suitable for grassed roads, car parks, light aircraft taxiways, equestrian surface reinforcement and grass verge protection.

Two tried and tested methods of turf reinforcement include plastic mesh systems and rubber crumb. Performing the functions of asphalt or concrete paving, the aesthetic value of a grass surface is still maintained. Providing impressive load-bearing strength, the turf reinforcement protects the vegetation root system of the grass from deadly compaction. And voids or air pockets within the material enable root development together with storage capacity for rainfall. Heavy rain is slowed in movement through and across the surface.

Ground solutions

A recycled plastic porous paver ProctorPave from A Proctor Group of Scotland allows users to park, drive and walk on a grass surface. Stormwater is slowed, which allows suspended pollutants and moderate amounts of engine oils to be consumed by active soil bacteria, aided by the system's oxygen exchange capacity. Easy to lay, this is a flexible grid system that will conform to undulating terrain and the material can be cut and shaped with pruning shears. After constructing a sub-base, the material can be laid from a 20sq m roll.

Marketing administrator Karrina Andrews says: "As this is a natural grass, surface water permeates through it."

ProctorPave has been installed at golf clubs as travelling areas for golf carts and in areas where firm grass is required to prevent mud pockets. Andrews adds: "A huge advantage is that the product can be used in conjunction with sustainable urban drainage systems (SUDS) allowing for the collection of rainwater where required."

The benefits of SUDS in terms of minimising flood risk are recognised by the Government in Planning Policy Guidance 25: Development and Flood Risk.

Boddingtons of Maldon in Essex reports that interest in turf reinforcements has increased dramatically. Marketing manager James Rowlandson says: "People are very aware of green issues and there is a culture developing that favours more natural, permeable surfacing."

Offering a high level of ground reinforcement, GrassProtecta is a heavy-duty extruded plastic grid available in standard and premium grades. Allowing full natural drainage, this grass protection mesh can be used as part of a SUDS. Coloured green, the high-density polyethylene mesh is made from 20 per cent recycled material and incorporates a blowing agent to produce a rougher surface that is less slippery. Before laying, uneven areas should be levelled off and any depressions filled with a mix of sand, topsoil and seed. Laid directly on the grass, the mesh - with 15mmx15mm apertures - is secured every 500mm to 1,000mm by steel U-pins. The grass grows through the apertures and intertwines with the mesh filaments to create a stable, reinforced surface.

Rowlandson says: "(Our) products have a high level of recycled plastic and this is being pushed forward."

Turfprotecta is a mesh made from extruded plastic, suited for pedestrian and light vehicle use. The black heavy-duty grade is manufactured from 100 per cent recycled high-density polyethylene (HDPE) and weighs 660g/sq m, while green is manufactured from virgin material with a small percentage of recycled polymer added.

Supplied in 2m-wide by 30m-long rolls, grass will grow through the turf reinforcement net and may then be mown, rolled and fertilised as usual.

Tenax UK supplies a grass paver that does not require the top surface of soil to be removed, thereby reducing installation costs. GrassLock is compacted into the ground, enabling grass roots to grow through the apertures to create a strong root mass that will support the weight of heavy vehicles. Alternatively, for temporary protection of grassed areas, TrackWay is supplied in panels measuring 1.2mx2.05m. Each panel weighs less than 10kg but is capable of supporting vehicles up to 20 tonnes.

Creating rubber crumb

It was in 1980 that the first rubber tyres were chopped up to create rubber crumb for an equestrian surface. The idea came from an Institute of Mechanical Engineers competition to find a use for recycled plastic from the manufacturing industry. Ray Lodge, chairman of Springway Arenas, suggested recycled tyres.

Lodge first used the product as an equestrian surface and has since written a book called All-weather Surfaces for Horses, published by JA Allen. Previously, waste rubber tyres had been dumped down mine shafts or were sent to landfill - but tyres buried in the ground eventually come back to the surface. Creating a crumb material for turf reinforcement meant they could be put to use in a positive way.

The National Trust was one of the first to use rubber crumb to preserve heavy-wear turf areas at its properties.

Lodge says: "We find 20mm is the best size for reinforcement as a lot of the fibre is exposed and the product simulates chopped up turf. Technically, rubber expands and when you tread on it airways and moisture ways are opened up. That is why it is so successful when used on turf, as it introduces oxygen into the soil. Small rubber granules do not generally work as well."

TRIED AND TESTED FOR HEAVY WEAR

At the National Trust property of Cliveden head gardener Andrew Mudge says: "Rubber crumb has just been used on a heavy wear area that stretches right across a historic view. This grass has to be used to access another garden."

Taking out the old turf, the existing soil was dug out to 150mm and the rubber crumb incorporated. Topsoil was replaced and then the two were cultivated together. Pleased with results, Mudge says: "This was completed in December and the grass has kept green throughout this summer."

Material was supplied by Springway Arenas and is 20mm size. Mudge says: "This seems to work more successfully than a smaller particle size as it absorbs more moisture."

He has also previously used rubber crumb in a car park and reports that this was reasonably successful, adding: "The crumb needs to be incorporated into the soil and then seeded as we did not find it very successful when applied as a topdressing."

The landscape division of Cheltenham Borough Council reports that rubber crumb is used on the football pitches of its sports and open spaces.

Landscape management officer for operations Richard Courts says: "This is mainly incorporated in goal-mouth areas to help with wear issues and drainage, and we have found the material highly successful."

Spiking with a hollow tine, the council then brushes the material into the slits that have been made. This is then filled in with soil and grass seed applied. Courts adds: "An alternative method, if time is restricted or where there are large divots, is to mix the crumb in with topsoil and apply it that way before sowing grass seed."

Cardiff City Council has just laid a plastic honeycomb grid system around an event area in Sophia Gardens.

Landscape officer within the parks service, Jonathan Green, says: "This was essential to protect the grassland of this historic landscape. Sophia Gardens was Cardiff's first park for public use, opened in 1858.

"Grass was getting torn up, and following a particularly bad incident last year when a circus was on the site, a decision was made to sort this issue out."

The product has also been used on service access roads but Green reports success has been varied. "Sometimes the grass has not taken very well but this could be due to a number of factors including the weather." Where a turf reinforcement material is used, the area is generally soil and seeded due to budget restraints.

At Rugby School, head groundsman James Mead says: "Plastic mesh has been used as a temporary car park when a new school gallery building was recently opened.

"As the school is a heritage site we cannot allow any damage to the grounds."

He adds: "I am currently looking at alleviating heavy foot traffic by using rubber crumb.

"The school has so many visitors coming to see the hallowed ground where the game of rugby was invented that we need to protect the grass areas they walk on."


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