How do you do a Bre 365 soakaway test?
In order to carry out a BRE 365 Soakaway Test you will need to excavate some trial holes, and fill then with water and watch how quickly in soaks away. In clay soils this can take a long time, so you may need to watch the hole for a few hours, in a gravel soils it could be all over in 10 minutes.
How do I calculate the size of a soakaway?
Where ground has good soakage (such as sand/gravel) then the size/volume of a crate type soakaway can be calculated as follows: Volume = Roof area being drained x (50mm rainfall rate per hr/3000). These soakaways are normally filled with clean brick/block/concrete pieces no larger than 150mm.
How deep should a soakaway be?
Soakaway Depth You should allow for 150mm base, side and top fill, plus a minimum additional 150mm top cover for garden applications (350mm for light traffic applications).
What is a good percolation test result?
A minimum value of 15 ensures that the soil’s percolation rate is slow enough to allow the effluent to be sufficiently treated before reaching the ground water. Any value lower than 15 would mean that the untreated effluent could drain away too rapidly and pollute the groundwater.
What are Soakaway tests?
The soak away test involves excavating a trial pit, filing the trial pit with water, recording the water level at specific time intervals in to establish the drainage rate, then repeating a total of three times in accordance with BRE 365 Soak away Design. …
How many soakaway crates do I need?
How many soakaway crates do I need?
| Effective Roof Area (Square Metres) | Size of Soakaway Required (Cubic Metres) | Number of Polystorm Crates Required |
|---|---|---|
| 40 m² | 0.8m³ (800 litres) | 4 |
| 50 m² | 1.0m³ (1000 litres) | 5 |
| 60 m² | 1.2m³ (1200 litres) | 6 |
| 80 m² | 1.6m³ (1600 litres) | 8 |
How long should a soakaway take to drain?
Pre-soak the hole by filling it to at least 300mm and leave for at least 12 hours to allow the water to drain away.
Do you fill soakaway crates with gravel?
Always cover the soakaway crates with a geotextile membrane to maintain the performance of the system. A layer of sharp sand or pea gravel should be put into place before the crates are lowered in, then the geotextile membrane should be fitted inside the hole, ready for the soakaway crates to sit on top of.
How deep should a soakaway be in clay soil?
1.8m deep
A soakaway is basically a deep hole filled with rubble. To work, it must extend below the clay and be at least 1.8m deep. Dig a series of parallel trenches every 3-6m across the garden, sloping towards the ditch or soakaway.
How long do soakaway worms take to work?
How Long Do The Worms Take To Work? Normally they take 2-3 weeks to unblock your soakaway.
How quickly should a soakaway drain?
If the water drains rapidly – If it drains within 10 minutes, the hole should be refilled up to 10 times. If the water continues to drain away then this soil is unsuitable for a soakaway. And if it hasn’t soaked away within 6 hours it is also not suitable.
When was BRE Digest 365 soakaway design published?
BRE Digest 365 Soakaway design. BRE (Building Research Establishment) is an independent, research-based consultancy, testing and training organisation, operating in the built environment and associated industries. BRE Digest 365 ‘Soakaway design’ was first published in 1991, when it replaced Digest 151.
What do you need to know about BRE Digest 365?
It also includes the methodology for the percolation test used in surface water soakaway design. The BRE Digest 365 method includes a number of specific design conditions and assumptions which must be considered, including the following; The BRE 365 Method does not include a variable Factor of Safety.
Why are soakaways used in fully sewered areas?
However, recently they have also been used in fully-sewered areas to limit the impact of new building works and to avoid the cost of upgrading sewers . Digest 365 describes the processes for the design and construction of soakaways and explains how to calculate rainfall design values and soil infiltration rates.
Why is there no infiltration through the base of the soakaway?
The BRE 365 Method also assumes that there is no infiltration through the base of the soakaway. This is because it is assumed that the base of the soakaway is concrete or will become blocked with sediments.