Climate change has made droughts and floods increasingly common, ensuring that Garden Designers have to take this into account when producing landscaping schemes. Careful use of hard landscaping can mitigate the problems of excess rainwater, while providing valuable resources for use during dry weather.
It is not just a matter of providing water butts or automatic watering systems. There are numerous ways of collecting rainwater, which are best installed when creating a new garden. Soakways have traditionally been used to direct water from one place to another within a garden and can be linked to a system of infiltration tanks.
UNDERGROUND TANKS
Enclosed underground tanks fed by pipes can be installed and linked to drainpipes from sheds, garages or houses. Placed several feet below the earth, the layers of soil keep water temperatures low thus reducing evaporation. Such underwater tanks are completely dark, and the water remains at a constant temperature of around 4° all year. The amount of rainwater that can be housed in these tanks is extensive.
At Ickworth House, Suffolk, a hidden rainwater cistern installed many years ago collects 1,000 litres of rainwater from the gutters and is used to water of most of the garden throughout the summer.
Installing underground tanks is best undertaken when designing paths and driveways within a garden due to the need to excavate large areas. Once the tank is installed, the use of permeable membranes and permeable block paving allow surface water to be directed into the underground tank. Using such surfaces reduces the risk of flooding around the outside of the house, or on nearby paths and pavements.
Hebden X Grid is a typical product used for this purpose. Made by British Recycled Plastic, it can be used on gravel pathways, boggy gateways as well as forming part of a sustainable drainage system. It reduces surface pooling since it creates a grid through which rainwater can drain away.
Gravel is often used on top of soil covered underground tanks, but wheelchair and pushchair users find this surface hard to move on. Consequently, resin based systems that bond gravel together while creating a porous, yet solid surface are proving increasingly popular.
REINFORCED GRASS
Reinforced grass is another popular water saving method and is particularly suitable for use in environmentally sensitive locations as it creates a green vista. It can also be used on front gardens where limited space often requires vehicles to be parked on what otherwise would be lawns and flowerbeds.
There are different ways installing reinforced grass systems:
- Block paving can be laid in attractive interlocking patterns involving pockets of soil, which can be seeded with grass or low growing sturdy herbs such as thyme.
- Concrete cellular paving can be obtained as pre-formed blocks. The holes in the paving can be filled with aggregate or grass.
- Plastic cellular paving is made from recycled plastic laid in an interlocking design. A special base may need to be created or in some cases the paving can be laid directly onto the turf and pegged in place. The cells are filled with soil and grass seed.
- Plastic mesh can be used on firm, well drained ground. It is laid over an area of existing turf or grass. This allows frequent use without damaging grass roots.
- In each case, the grass can be mowed as required during the growing season and creates a very hard wearing, green environment.
KUSAN DOI
This is an unusual but very decorative water saving system that can provide an interesting garden feature when it rains. Originating in Japan, Kusan Doi traditionally involves a series of small cups with holes in the bottom. Hung vertically along a chain from the gutters, gravity ensures that the water passes from one cup to the other, cascading like a small waterfall, ending in a drainage hole in the ground where the water passes to an underground tank. Similar effects have been achieved using lengths of chain, groups of keys, long lengths of wire spirals, mugs, ceramic tubes and even small tins.
RECYCLED MATERIALS
Driveways, patios, terraces and paths made from recycled materials that can be linked to sustainable water systems are increasingly common. One such material is Oltco’s Recycle Bound, a unique resin bound solution made using waste plastic obtained from plastic recycling points. Recycle Bound surfaces are made using a combination of plastic drink bottles, plastic food packaging and plastic straws. Hard wearing, non-slip, easy to clean and extremely durable, every square metre of Recycle Bound contains the equivalent of 3,000 plastic straws, ensuring that a standard 50 square metre drive involves the recycling of 150,000 plastic straws. As the material is totally porous, water drains away easily from the surface and can be linked into sustainable urban drainage systems. Recycle Bound plastic resin pathways have been installed within the biomes at the Eden Project in Cornwall, creating an extensive network of paths that are low maintenance, sturdy and environmentally friendly as they utilise the equivalent of 255,000 straws.
REGULATIONS
Whatever method you choose, it is important to comply with relevant building regulations. Rainwater reservoirs and soakways, must be installed no closer than five metres from a building or 2.5m from a boundary. Consideration must also be given to the type of ground into which the chamber is to be installed, and it is advisable to check first with the Environment Agency before designing such features.
Incorporating some form of rain saving measure minimises future drainage or watering problems, and ensures that the garden can be kept looking good whatever the weather.
Angela Youngman
Author of Recycling in the Garden White Owl books
angelayoungman@aspects.net