What is a BRE 365 Test?
Before understanding why a BRE 365 test is important, we have to the question, “What is a BRE 365 test?” Well, a BRE 365 test (infiltration test or soakaway test) is an important tool to measure how quickly water can get into the ground. It’s a key part of sustainable urban drainage systems (SuDS) and helps with surface water management. The purpose of this test is to see if a natural underground drainage system is possible for a particular site, so water can be managed sustainably and reduce flood risk. IBEX Consultants, experts in environmental and drainage consultancy, often assist in carrying out these tests to ensure accurate and reliable results.
Why is the BRE 365 Test Important?
The BRE 365 test is developed by the Building Research Establishment and is crucial for surface water drainage, especially in areas that experience heavy rainfall or flood risk. Lead local flooding authorities and local planning authorities often require the test as part of the planning process. It informs the design of SuDS to stop surface water from overwhelming drainage systems and causing local flooding.
When is the BRE 365 Test Needed?
A BRE 365 test is usually required at the planning application stage of a development to show that the ground can absorb water from surface water networks, such as roofs or paved areas. If the site can’t absorb enough water, a different drainage strategy or other infiltration devices may be needed to stop water from pooling or causing damage.
How is a BRE 365 Test Conducted?
- Trial Pit Excavation: A trial pit is dug to the depth of the proposed infiltration device, usually a soakaway.
- Water Infiltration: Water is then poured into the pit, simulating a storm event. The rate at which the water gets into the soil (the infiltration rate) is measured.
- Soil Conditions Assessment: The soil type, ground conditions, and underlying geology are checked to see if the soil can absorb water.
- Percolation Test: This involves measuring the soil infiltration rate through percolation testing to see how long it takes for half the volume of water to drain away.
The test must consider factors like soil conditions, a high water table, and whether the proposed soakaway is suitable for the site layout.
Soil Infiltration Rate
The soil infiltration rate is a critical factor in designing a drainage system. If the rate is too slow, surface water will build up and overwhelm the drainage systems, leading to an increased flood risk. If the site has a high infiltration rate, it can manage water better, reducing surface water runoff and local flooding.
Sustainable Urban Drainage Systems (SuDS)
SuDS is a modern way of managing surface water by mimicking natural absorption processes. In these cases, SuDS capture surface water and encourage it to infiltrate the ground, helping manage flood risk and promote groundwater recharge. Local flood authorities and planning authorities require SuDS reports to ensure the drainage system is designed to manage storm events and reduce the risk of flooding. Proper testing informs the SuDS design so that the drainage systems are installed correctly and function efficiently.
Infiltration Devices
The proposed infiltration device (soakaway) must be designed for the site’s specific ground conditions. Soil type, water absorption rate, and available space all play critical roles. If the site’s soil can’t absorb enough water or the water table is too high, alternative infiltration devices or drainage strategies may be needed to prevent surface water flooding.
Planning Process and Local Authority Involvement
The BRE 365 test is key during the planning process. Before construction begins, developers must demonstrate that surface water management is feasible on the site. Local planning authorities require this evidence to approve the development, and lead local flooding authorities ensure the site layout allows for enough water infiltration to prevent flood risk.
BRE 365 Testing for Development Proposals
Developers must manage surface water in development proposals, especially in areas with high surface water runoff. The BRE 365 test ensures that the proposed soakaway or infiltration device can handle the volume of water expected during heavy rainfall.
How Does a BRE 365 Test Affect Drainage Strategy?
The results of a BRE 365 test inform the drainage strategy. If infiltration testing shows that the site can absorb enough water, soakaways or other infiltration devices can be designed. If the infiltration rate is low, a different drainage strategy may be needed to manage surface water runoff.
Factors That Affect the BRE 365 Test
Several factors can impact the BRE 365 test:
- Soil Type: Certain soils, like clay, have poor infiltration rates and may not support soakaway designs.
- High Water Table: If the water table is too high, infiltration devices will fail.
- Ground Conditions: The condition of the ground, including its compactness and underlying geology, determines how well it can absorb water.
- Site Layout: Available space and proximity to buildings or other infrastructure can influence the type of infiltration device used.
Summary
A BRE 365 test is an essential part of the planning process for surface water management. It determines whether a soakaway or infiltration device is possible on a site and ensures that the surface water drainage system will function effectively. By understanding soil and ground conditions, the test provides valuable data to inform drainage strategies and prevent flooding. With the support of experienced environmental consultants like IBEX Consultants, developers can manage water sustainably, protect the environment, and comply with planning regulations.
