When designing sustainable urban drainage systems (SuDS) or natural underground drainage systems, water management is key. BRE 365 testing is a key part of determining if a site’s ground conditions are suitable for surface water to drain through soakaways or other infiltration devices.
This article explains what BRE 365 testing tells you, why and how it helps with surface water management and development proposals.
BRE 365 Testing
What is BRE 365?
BRE 365 is a set of guidelines to determine if the soil is suitable for proposed soakaways or other infiltration devices. It looks at the soil infiltration rate which is how quickly rainwater can infiltrate into the ground.
This in situ test is often done at the design stage of a project and is a foundation for planning surface water networks, permeable paving and surface water sewers. Local planning and flooding authorities, including lead local flooding authorities, often require this test as part of the planning application to ensure compliance with drainage regulations.
BRE 365 testing, a crucial step in determining soil suitability for soakaways and other infiltration devices, can be professionally conducted with the expertise of Ibex Consulting Engineers.
BRE 365 Testing Results
BRE 365 testing provides the information that informs the site layout, drainage design and compliance with regulations. Here’s what it tells you:
1. Soil Infiltration Rate
The soil infiltration rate is the key output from the test. It tells you how quickly surface water will run off the ground, whether the site can accommodate a proposed infiltration device or if alternative methods like attenuation tanks are needed.
2. Ground Conditions
BRE 365 testing shows the underlying geology, soil type and water absorption rate of the site. For example clay soils have a low infiltration rate so are not suitable for soakaways or similar systems. In these cases alternative methods will be required.
3. Suitability for Infiltration Devices
Whether you’re proposing a soakaway, a natural underground drainage system or other infiltration devices the test will tell you if the site can cope with heavy rainfall and prevent flooding or erosion.
4. System Design and Compliance
The results will guide the design of sustainable urban drainage systems (SuDS) so they are installed correctly to deal with storm events and meet local planning authority requirements.
The BRE 365 Testing Process
The BRE 365 process involves several steps to assess infiltration potential. Here’s what it looks like:
- Site Investigation: The first step is to find a suitable location to test, taking into account the underlying geology and space for drainage systems.
- Trial Pit Excavation: A trial pit, 1m x 1m x 1m, is excavated on site. This allows water to infiltrate into the ground under in situ conditions.
- Water Infiltration Test: Water is poured into the trial pit simulating a storm event or rainwater runoff. The half volume method is used to measure how quickly the water level drops.
- Data Collection and Analysis: The infiltration rate is calculated from how long it takes for the water to infiltrate into the soil. This data is needed to design systems with the correct volume and capacity.
Why BRE 365 Testing?1. Surface Water Management
BRE 365 testing prevents surface water from overwhelming the drainage system, reduces the risk of flooding and protects the local environment, including nearby rivers and infrastructure.
2. Planning and Compliance
At the planning stage many local planning authorities and lead local flooding authorities require SuDS reports that include BRE 365 results. The test ensures development meets regulations and best practice.
3. System Design
Whether it’s permeable paving, surface water sewers or soakaway tests BRE 365 testing provides the data to design the system to the site.
4. Long Term Risk Reduction
Proper testing reduces the risk of erosion, flooding or structural damage from poorly designed drainage systems.
BRE 365 Testing ApplicationsFor Developers
Development proposals benefit from BRE 365 testing so drainage systems are designed to the soil type and site layout to avoid costly retrofits.
For Homeowners
If you’re building an extension the test will help design a drainage solution with enough capacity for rainwater and surface water runoff.
For Engineers and Architects
Professionals use the BRE 365 results during the design stage to avoid problems from poor ground conditions.
Notes
While BRE 365 testing is useful there are some limitations:
- Seasonal Variability: Results may vary depending on the time of year and weather conditions during the test.
- Clay Soils: Sites with clay soils often require alternative methods as infiltration rates are low.
- Space Constraints: Limited space may mean soakaways or infiltration devices can’t be as big as needed.
In these cases professionals may need to look at alternative drainage solutions or consult with experts to meet compliance and functionality.
Summary
BRE 365 testing is a key part of designing good and sustainable drainage. By measuring the soil infiltration rate, ground conditions and system capacity it provides the data to design systems to handle surface water runoff.
Small or big project BRE 365 testing ensures compliance, sustainability and resilience to heavy rainfall and storm events. Contact a professional today for percolation testing and get your site on the path to good drainage.
Surface water management is more than a planning requirement it’s an investment in a sustainable future.
