What is a rain garden?
Put simply, a rain garden is a shallow area of ground or dip which receives run-off from roofs and other hard surfaces. It is planted with plants that can stand waterlogging for up to 48 hours at a time. More drought-tolerant plants are used towards the edges. Storm water fills the depression and then drains. Plant a Rain Garden Specially designed areas planted with native plants, called rain gardens or grassy swales, can provide natural places for rainwater to collect and soak into the ground. Rain from rooftop areas or paved areas can be diverted into these areas rather than into storm drains.The best spot for a rain garden is somewhere between the source of the runoff (roofs and driveways) and the runoff point (drains, streams, low spots). The garden should not be within 10 feet of the foundation of the home; it should be located in partial to full sun; and make sure to avoid underground utility lines.Dry wells, soil amendment and rain gardens are used to infiltrate water into the soil. These solutions have many environmental benefits: reducing runoff from your property, filtering runoff, watering your yard and recharging groundwater. They can also be combined with structures that redirect runoff.
Where is the best place to put a rain garden?
The ideal rain garden location is a flat or gently sloped area and is down slope from a runoff source. Site your garden at least 10 feet away from any structures (unless an impermeable barrier is used) and 5 feet from property lines. In other words, if there is approximately 500 square feet of drainage area, the rain garden should be about 100 square feet. The average homeowner rain garden is usually between 100–300 square feet, and the minimum ponding depth is 4″ with an average ponding depth ranging from 4–8″.
What is the difference between a soakaway and a rain garden?
Rain gardens and soakaways A rain garden is a depression in the garden to collect and store rainwater before allowing it to soak away into the ground or flow to the drains. Soakaways are a similar idea where water is piped into a gravel-filled trench or geocellular box and allowed to soak into the ground. It’s a highly efficient and environmentally friendly way to deal with excess surface water. The pipe leading into the soakaway system acts like a gutter, meaning it’s an additional measurement in place to reduce the risk of flooding.Quite simply, a soakaway is a hole in the ground that is filled that allows water runoff to slowly drain and redistribute itself into the soil. Modern soakaways are best formed using high volume (for any given size) crates, rather than the more traditional low water storage volume which rubble and gravel offer.The main problem people find with soakaways is that they can easily become blocked with silt and leaves that wash into them over the course of time. Once they become completely clogged can seem like more of a pond than a soakaway.Implementing appropriate landscaping techniques can aid in directing water away from the soakaway. Techniques such as creating gentle slopes away from the property or installing simple drainage systems like French drains can prevent excess water from pooling near the septic tank or sewage treatment plant.
How deep does a rainwater soakaway need to be?
How deep should a soakaway be? The Perforated pipe should be laid at a minimum depth of 200mm and a maximum depth of 700mm. This enables aerobic contact between the effluent and the drainage stone and soil particles. This leads to aerobic digestion and effectively treats the effluent. If your Soakaway has failed then the wastewater will have nowhere to go. The system will quickly fill up and prevent further wastewater from entering the system. If the problem is not fixed any holding point in the system will fill up and overflow. Also inspection chambers, open drain points will overflow.The Building Regulations and BS 6297 2007 state that the sewage effluent MUST be in constant contact with the AEROBIC particles of the soil. As the aerobic soil layer ends at 1 metre below ground, soakaway pits are not allowed.