Since April 2015, the majority of development sites must be assessed for potential use of SUDS. Due to high demand, Roberts Environmental has developed an in-house soakaway testing service (in accordance with BRE365 guidelines) which is offered as part of our ground investigations. Soakaway testing forms an important part of assessing the viability and design of SUDS. Here we discuss why it is so important…

Why use SUDS?

Sustainable Urban Drainage Systems (SUDS) are an alternative means of disposing of surface water from buildings and paved areas to the more conventional piped means.

By mimicking the way rainfall drains naturally, it is believed that their use has positive environmental benefits, such as improved water quality and decreased flood risk.

SUDS also help counteract the impact on our water cycle caused by increased urbanisation, such as reduced infiltration, which in turn can result in diminished groundwater supplies.

Where SUDS are designed to make efficient use of the space available, they can often cost less to implement than underground piped systems.

Since April 2015, planning applications relating to developments of 10 dwellings or more; or equivalent non-residential or mixed development, have to assess a site for the suitability of the use of sustainable drainage systems.
Discharging surface water into a drain of a development can only be permitted if other SUDS techniques have been considered and proven to be unsuitable.

Soakaways and Soakaway Tests

Soakaways are a type of SUDS which are used to limit the impact on discharge of new building works and to avoid costs of sewer upgrading outside a development.

They store the immediate surface water run-off and allow for its efficient infiltration into the soil.

A soakaway test is a method for calculating a ground’s permeability characteristics in preparation for a possible soakaway within a surface water SUDS.

Understanding the permeability of the ground is a critical step in ensuing that the correct drainage system is chosen, and is now forming a key step in obtaining planning permission.

When Soakaway Testing Isn’t Required

If a site investigation clearly demonstrates that ground conditions are unlikely to support soakaways then testing may not be required. Appropriate ground investigation and testing will be necessary to prove that the ground conditions are unsuitable.

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