Rain Gardens/Bio Retention systems

Rain gardens/bio retention systems

Modern-day landscapes (generally) consisting of concrete and other impermeable surfaces combined with the removal of vegetation has resulted in increased surface water runoff. Unfortunately, the growing trend to pave over their driveways and front gardens mean that rainwater is directed straight into drains, which can be overloaded in heavy rain and storms; these two factors result in frequent localised flooding. 
The concept of the rain garden has become popular with local authorities in helping flood prevention. In their simplest form “they are a shallow permeable planted bed that is designed to receive run-off from a paved area or roof. 
Here at New Horizon Horticultural Services, we offer services to install rainwater gardens, water harvesting, stormwater planters and landscape swales and ponds. As well as helping to prevent flooding, rainwater management can make attractive ornamental features in your front or rear gardens, and can also benefit wildlife, attract bees and other pollinating insects.

What are rainwater gardens?

Our gardens aren’t always well-equipped to cope with heavy rain. Water easily runs over concrete and other impermeable surfaces, pouring into the drainage system and sometimes overloading it. This can have serious consequences; the drains fill up and water spills out, endangering people and damaging property. Rainwater gardens can be part of the solution. By looking to nature, and learning from its drainage systems, we can reduce the threat to our properties and environment.
Rainwater gardens are basically shallow depressions, planted with flowers and vegetation, which are designed to absorb surface runoff. They capture water, slowing the rate at which it enters the drainage system whilst allowing water to filter back into the natural water course, significantly reducing the risk of flooding. As surface water runs over impermeable surfaces, it picks up pollutants like oil and fertilisers, washing them into our waterways. But rainwater gardens have an additional benefit that they help recreate the natural water cycle and reduce water quality problems by filtering this poor quality water through their soil and plant roots. This filtration helps remove solid and dissolved pollutants protecting our streams and ditches.

Services offered:

Design and installation of:
  • Rain gardens/bio-retention systems
  • Stormwater planters
  • Landscape swales, rills and channels
  • Rainwater harvesting and storage
rain water flow

How do rainwater gardens work?

Rainwater makes its way from the roof to drain via a gutter/downspout. Normally this happens without a problem. However, during periods of heavy rain, water can pour into the drain faster than it can flow away, causing flooding.

By redirecting water from your downpipe into a rainwater garden, you can ease the pressure on the drainage system and nourish a healthy bed of vegetation in the process. In others, you’ll need to create a channel, the easiest way to do this is via a lined swale, a small passage which can carry water down an incline to the mouth of the rainwater garden.

The rainwater garden itself is a shallow depression with a wide mouth running at a right angle to the flow of water. It needs to be dug on a slope with the downhill end and sides walled around by a soil berm (a raised bank around the garden edge). The berm will hold back water during a storm. In most cases, the garden will have an overflow provision, this might be an existing drain or an alternative drain. For this to work effectively, the overflow point will need to be higher than the receiving drain.

By changing our outside space, we can help reduce localised flooding and at the same time provide benefit to both wildlife and people. Gardens, whether small or large, can also play an additional, important part in greening our urban and suburban environments. Furthermore, it helps to reduce garden flooding, providing a source of habitats for wildlife and improve water quality.
rain garden planter
"We can’t thank Andrew and his team enough for the great job they did with our garden. We had the whole garden cleared and then landscaped. We are really happy with the result and the quality of the work. The only access we have to the garden is through our house so we were keen to get the job completed as quickly as possible to minimise the disruption. Andrew and his team worked really hard and the project was completed on schedule despite there being some heavy rain. We would definitely recommend this company due to the high quality of the work and how efficient they were."
- Sarah Gonsalves, Newcastle
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