What Is BRE365 Testing?
What Is BRE365 Testing?
BRE365 testing is a method used to determine the water absorption rate of soil in order to assess whether surface water arising from development proposals can be treated at source.
The test involves measuring the infiltration rate of the soil, typically for major developments where a desktop geological study shows underlying geology with potential for infiltration. The process includes excavating a hole, filling it with water and measuring how quickly it drains away.
BRE365 testing is also known as percolation testing or perc tests. It is often requested by local planning authorities (LPAs) and local lead flood authorities (LLFAs) when assessing soakaway installation suitability.
Geo-Integrity offers BRE365 soakaway testing services which involve carrying out an in-situ test to guidance document BRE 365.
The process of testing for BRE365 requires the excavation of a trial pit, which serves as a model for the proposed soakaway. Mini-diggers like CAT or JCB are commonly used to excavate the pit, although manual excavation is also possible.
The pit is then filled with water several times in quick succession, while measuring the rate of percolation. The results obtained from these calculations can be useful in determining the appropriate size of the required soakaway.
In 1991, the Building Research Establishment (BRE), a leading consultancy in the field of building science, issued guidance on the design of soakaways, which are used to manage stormwater runoff.
The guidance provided not only construction advice but also detailed information on calculating soil infiltration rates, which led to the development of the BRE 365 testing method.
To comply with these guidelines, soakaways must demonstrate that they can effectively drain water to provide the necessary runoff support during heavy rainfall. The BRE Digest recommends that soakaways should be able to discharge from full to half-volume within 24 hours.
As a respected authority in the field of building science, following the BRE’s guidance on soakaway design is highly recommended.
How Long Do Soakaways Last?
Soakaways are a great long-term option when it comes to drainage solutions as they can happily last for over 100 years if installed correctly and BRE 365 tests have been carried out with satisfactory results. While they don’t require active maintenance it’s wise to check them every few months to ensure everything is still running smoothly.
With the right care and attention, your soakaway should remain in perfect condition for many years!
Is BRE 365 For Roofs Or Driveway
The BRE 365 soakaway method is a versatile solution for dealing with water run off from any impermeable surface, such as roofs and driveways.
All that needs to be done is to add up the total area of the surfaces with 0% permeability, before inputting these results into the model.
Furthermore, more sophisticated software can even split this figure down further if you were to use permeable paving – making it possible to input a 30% impermeability figure, which would reduce the overall volume of attenuation and size of the soak-away required.
Will BRE 365 Testing Tell Me The Size Of Soakaway?
Yes, BRE 365 can tell you the size of the soakaway provided your proposal meets the minimum criteria specified by regulations.
This usually entails that the top of the soakaway should be at least 1 meter below ground level. If this is not met, then a calculation cannot be carried out and thus, no size can be determined.
However, if it does meet all relevant criteria, then a size will be given as an output and in some cases a selection of sizes will also be available so that there is some flexibility in positioning the soakaway to best suite its needs.
Is Sandy Soil Good For BRE 365 Soakaway?
Sandy soil can make for a good soakaway, but the effectiveness depends on the proportion of sand and other components such as clays and silts mixed in.
Clean, washed coarse sand will give better results than sands with increasing percentages of clay, which will become similar to that of ‘pure’ clay.
As such, for optimal results it is best to test the composition of soil before attempting to create a soakaway.
