The Environmental Gains
The rapid development of previously green-field sites and the associated creation of impermeable areas such as roofs, car parks and footpaths will mean that at project conception stage there will be potentially large volumes of surface water to be dealt with. Traditionally this has been done by piping the surface water into storage tanks or discharging it into nearby streams or surface water drainage. Planners and designers do not currently favour this method of drainage, as it simply moves the surface water downstream where it still has to be dealt with. Piping large volumes of water into streams and rivers increases the risk of flooding and also allows for the potential pollution of local watercourses and drinking water supplys.
Planners are encouraging the use of Sustainable Urban Drainage Systems (SUDS) in all new developments. In particular the use of appropriate source control techniques is important, as this allows for the containment of the surface water collected on the site and for it to be dealt with on-site as opposed to traditionally draining it off-site.
A SUDS based permeable system, such as Kilsaran’s permeable Clima-Pave range, is designed to link the roof and path with the driveway/car park, and will capture the rainfall and excess flood water and discharge it into the sub-base / ground. Even during times of heavy rainfall such a system works efficiently and has the added advantage of operating as a floodwater control method. The ability to recycle and reuse rainwater is environmentally compelling. These systems are affordable and effective at harvesting rainwater that can be reused within the building (potable use) or for watering the garden and washing vehicles.
Applications of SUDS include the construction of ponds, wetlands or swales with new developments, the soaking of water from impermeable areas e.g. roofs, into soakaways and maximizing the amount of permeable on a given site. Permeable paving is a range of sustainable materials with a base and sub-base that allow the movement of stormwater through the surface. In addition to reducing runoff, this effectively traps suspended solids and filters pollutants from the water. Permeable paving is the most effective way of ensuring that a site can still be used as an urban surface for traffic or pedestrians, without adding to the runoff that typically increases when urbanisation occurs.
Advantages of Permeable Paving
- Permeable Paving is a ‘source control’ method. Water is managed and dealt with on-site without piping off to storage tanks or surface water treatment systems.
- The Water Framework Directive (Directive2000/60/EC) requires that surface water discharge is managed to ensure that risk of contamination or pollution are mitigated. Permeable Paving systems filter contaminants by microbial action. There is no requirement for additional filtering/polishing with Permeable Paving in normal use
- Separate attenuation tank systems are not required
- No need for gullies or channels or conventional drainage
- Recharges ground water
- Roofs, roads, and other non-permeable areas can be discharged into permeable paving (no gullies required)
- No ponding or surface water
- Collected water can potentially be re-used for non-potable purposes
- Improves water quality