Visual Soakaway Design Version 4 incorporates a more logical and customisable user interface with some added design features…

The Visual Design Window

The designer can now see and manipulate a 3D visual representation of either a trench or ring soakaway. The visual soakaway can be moved anywhere within the window and designed in real-time thus reducing the total design time.

Soakaway Maintenance Schedule

Due to the importance of maintenance, we have produced a schedule which can be printed off and kept on file to allow the useful life of the soakaway to be monitored.

Filter Trench Design Option

In addition to the soakaway design functionality, the designer may opt to design a filter trench. A filter trench is essentially the same as a soakaway except that a specified portion of the surface runoff is allowed to discharge through an overflow pipe. In this way, surface water from a site can be treated by infiltration through the fill media prior to discharge to a watercourse and also removes the need for total storage within a traditional soakaway.

Flat Soakaway or Base Infiltration Option

In previous versions of Soakaway Design, the designer was restricted to the fact that the design only allowed trench soakaways to exfiltrate water through its sides (and not its base) to half the effective depth.

In Version 3 the designer has the option of including the base of the trench soakaway in his/her design, thus making it possible to analyse the behaviour of a permeable surface for surface water drainage. eg. porous block paving.

Failure Depth of the Ring Soakaway

Previously the failure depth of ring soakaways was set to 4 metres. This is now entirely at the designers discretion and can be modified at design time. However, the failure half emptying time is still set to 24 hours.

Ring Soakaway Surrounding Fill and Margin Variable

Another new feature in Version 4 is the option of including the granular fill surrounding the ring soakaway for storage purposes. This allows for a slight reduction in depth in the finished design.

The Margin variable has been introduced to account for the width around a Precast concrete ring soakaway which may be filled with granular fill material. The Margin variable is set in the Design Options window as shown below.

Z1 and Z2 Factors

In keeping with the design methodology of the BRE 365, the design rainfall can be calculated to a more accurate statistical level using the Z1 and Z2 factors for various regions of the UK. Click here to learn more.

Factor of Safety

The factor of safety coefficient has been included to allow the designer greater margins of comfort in sites where flooding is an issue. The infiltration rate of the soil is divided by the factor of safety within the design calculations and, therefore, increases the overall size of the soakaway.

Soil Infiltration Table

This feature must be used with caution!

The table is provided purely as a guide to allow for a rapid nominal design based on an estimated infiltration rate. It is vital, for a soakaway to work effectively for its design life, that a porosity test is carried out on site.