Drainbelt and Draintube are a practical, cost-effective and highly performing alternative to other forms of conventional drainage;
Sand and gravel banding is a commonly used method for the intensive drainage of golf and sports turf. It works by diverting rainfall along the surface and into sand/gravel slits spaced approximately 1m apart that are cut perpendicular to perforated pipe drains spaced at 6-10m intervals. Sand/gravel banding is essentially a form of surface drainage, removing heavy rainfall from the surface and taking it away.
However sand/gravel banding doesn’t remove water from the soil, it merely diverts water from an already saturated soil. A capillary break exists between the soil and the sand/gravel band, meaning once the surface water and free water in the soil is removed, drainage stops and the soil stays wet at Field Capacity. See the section on how it works. This is especially noticeable with clay soils, where sand/gravel banding removes puddled water at the surface but leaves the soil wet. In this instance the conventional solution is to apply a heavy top dressing of sand or to ameliorate the soil/root-zone with sand to present a drier playing surface. Sand and gravel banding is expensive and involves a great deal of machinery to transport and distribute the materials.
Drainbelt replaces the function of the sand/gravel bands and actively removes water from the soil and keeps removing water even when the soil is below the Field Capacity state. This negates the need for the importation and placement of large quantities of sand. Furthermore Drainbelt is longer lasting as it doesn’t suffer from clogging from fine particles migrating into the sand/gravel slits or into the perforated pipe.
The siphonic action of Drainbelt means the spacing between the collector pipes can be placed much wider apart (10-20m as opposed to 6m for conventional drainage), and therefore fewer trenches are needed to be excavated for the transportation of water away from the site.
The capillary action of Capiphon Drainbelt means the belts can be spaced wider than sand/gravel slits, typically every 1-3m rather than 0.5-1m.
Drainbelt can be installed by a vibratory mole-plough, which greatly reduces cost, time, disturbance and disruption for its installation.
With the demands of the modern golf and sports venue requiring all year round play and quick return to playability after a rainfall event, many developers turn to removal of topsoil and replacement with a deep sand-cap of 100-150mm. This is extremely costly and not environmentally sustainable, requiring much transport and site operations with heavy machinery. It is also very time-consuming during construction, putting pressure on construction timetables.
Drainbelt and Draintube systems negate the need for the sand cap and is more cost-effective and quicker to install.
The conventional method to construct a USGA-type golf green and an equestrian arena/manège (aka “ménage) is essentially the same principle. It involves a gravel/stone/grit layer upon which the root-zone (golf) or working surface (equestrian) is placed. This requires the transportation of significant amounts of gravel to the site and then to distribute and place it on the sub-soil base.
Furthermore when the stone layer is coarse and the bridging factor not satisfied, a blinding layer (typically geotextile or coarse sand) is required between the stone layer and the root-zone/working surface to prevent migration of fine particles into the stone layer and subsequent deterioration of its drainage function. If a geotextile layer is used, as in the case of most equestrian arenas, over time the geotextile fabric gets clogged with fine particles, reducing drainage performance.
Drainbelt replaces the gravel layer as the means of drainage and negates the need for a blinding/geotextile layer.
The USGA system involves suspending a water table within the root-zone soil. The suspension of this water layer is created by the capillary break between the root-zone and the gravel/grit layer. Excess free water drains out through the profile, leaving the root-zone soil at Field Capacity state. The USGA greens section construction is widely used throughout the golf construction industry, but it is expensive to build especially if the gravel/grit layer cannot be sourced locally.
Drainbelt and Draintube works differently by continually sucking moisture out of the root-zone/soil, actively drying the soil out; indeed it is so effective that it is recommended to install a valve or stopper in the carrier pipe to stop the flow of water and arrest the siphonic effect during the irrigation season.
The “California” type of greens construction is often used instead of the USGA type and can help make significant cost savings in construction. The California system has a root-zone of 250-300mm of pure sand (or mixture of soil and sand) over the natural sub-soil, with a network of perforated drainage pipes in the sub-soil base to remove the water. For this to work the root-zone layer has to have high hydraulic conductivity. The corollary to this is that fertiliser application is often high due to the poor nutrient status of the sand. Also there is no water retention in the sand and so irrigation water consumption tends to be higher than with the suspended water table of USGA-type greens. This is because with the California-type construction, the sand is congruous to the underlying soil and the perforated drain pipe, so there is no capillary break.
Drainbelt and Draintube can be used in an adaptation of the California system. With Drainbelt installed, the root zone can contain a higher percentage of soil and less sand. This has the benefit of the root-zone retaining more nutrients. The reduction in hydraulic conductivity is compensated by the capillary and siphonic action of the Drainbelt, thus maintaining comparable drainage performance. During the irrigation season, the discharge of the carrier drain can be closed with an isolation valve or stopper, stopping the flow of water and arresting the siphonic effect of the Drainbelt, thus correcting the downside of the “pure California” system, which has higher irrigation water consumption during the summer.
Drainage is often problematic on traditional “push-up” style soil-based golf greens. Hollow coring and filling the cavities with sand is a common technique to improve drainage and aeration. However the drainage performance of this method is limited unless the sand cores are congruous with a free draining layer below. Its limited effectiveness means that this operation is often repeated many times over, with the long term goal of replacing a high proportion of the natural soil with a sand. This is expensive, disturbs golf play and can impoverish the nutrient status of the soil, requiring higher applications of fertiliser and also irrigation water to wash it in. Drainbelt is a more effective and longer lasting method to drain a traditional “push-up” soil-based green. It’s a one-off installation of typical 1 day per green. Installation is by mole-plough, followed by a light roller so the green is back in play the next day, with no cores to remove or complaining golfers to appease. Drainbelt is installed at 300-450mm depth to facilitate aerating/tining operations.
Drainage of bunkers has long been a significant challenge for golf courses. Recent innovations have included capillary concrete and resin-bound rubber crumb. These are effective bunker construction methods, but they require a specialist contractor to build and once built you can’t easily modify or remove the bunker. Drainbelt is easy to install, doesn’t require a specialist contractor and can be easily removed and re-used if you decide to change bunker in the future.
Geo-cuspate fin drains, like other conventional drainage systems, remove only the excess free water from soil. Once this excess water has flowed away, drainage rates significantly reduce leaving a very moist soil. However Drainbelt and Draintube continue to suck water from the soil, meaning the soil is in a drier state prior to the next rainfall event than it would otherwise have been with a conventional drainage system. Drainbelt and Draintube are very easy to install in this application, see typical installation detail here