Applications

Infiltration

Infiltration systems store water temporarily. With the potential to provide a cost effective solution to many site drainage problems, they are generally divided into two categories depending whether temporary storage takes place above or below ground level.

Above ground infiltration systems utilise natural or artificial surfaces. Their shape and size may vary considerably from near level surfaces to basins and swales that have distinct sloping sides. Typical examples of above ground systems include porous pavements and paviours or infiltration basins and swales.

Below ground or sub-surface infiltration systems offer temporary storage of surface water below ground level. Conventional soakaways are the most common example, although alternative options include the use of trench style soakaways and infiltration blankets that utilise perforated pipework over a large plan area for dispersal.

Waterloc cells, wrapped in geotextile and buried underground form a high efficiency soakaway with a void ratio of 96%.

Attenuation

In principle this consists of the temporary storage of surface water in a suitable chamber below ground level. This chamber needs to be of sufficient size to accommodate the calculated run off during peak periods of rainfall. The stored water is then gradually released in a controlled manner into a surface water or combined drainage system or watercourse, subsequently eliminating the risk of flooding.

Increasingly, as existing sewer networks approach their capacity, attenuation systems offer a cost effective solution for accommodating additional catchments without increasing the size of existing sewers.

It is often a requirement that the rate of outflow from an attenuation scheme is controlled, whether a green or brownfield site. The Flowloc flow control device is designed to control discharge rates from such schemes. Flowloc is supplied within an integrated chamber base, which also includes a filter unit. This chamber allows easy non-man access from ground level and can also be used upstream without Flowloc as a silt trap. Available in six pre-set flow regulation rates. Two orifice plates are also available.