Above Ground Mound Soakaways

Above-ground mound soakaway systems, or mound systems, were developed by WTE Ltd. and copyrighted in 1996, to compensate for clay and impervious soils and high water table ground that cannot utilise a standard underground soakaway drainfield.

The Basics of our Above Ground Soakaway Mound System

All septic systems have 2 parts. The first part is the septic tank or, preferably, the sewage treatment plant, which collects solid waste called "sludge". (Septic tank effluent tends to clog mound systems)The second part is the soakaway drainfield which uses the local soils to absorb the liquid sewage (effluents) through an underground system of perforated pipes. The soil not only soaks the liquid away, but the naturally occuring soil bacteria destroy the pathogens in the sewage effluent before they enter the groundwater and contaminate drinking water supplies. Because many parts of the UK fail the requirements for normal underground soakaways, WTE Ltd. developed an above ground mound soakaway system which we Copyrighted in 1996. It was accepted by the Environment Agency in 1997 and now is included in Section H2 Building Regulations, though the actual design method and sizing criteria is not revealed due to our copyright.

How the above ground mound system works

The effluent from the septic tank, or, preferably, sewage treatment plant (the mounds tend to become clogged if septic tanks are used) is drained to a pumping station which pumps it up into the drain-pipes in the absorption bed of the mound.

The effluent then drains through graded layers of sand/gravels to neutralise the pollutants before draining both vertically and laterally into the topsoil under the mound.

Construction of the soakaway mound

The land underneath the mound is first ploughed to open up the surface and improve absorption. Layers of sands/gravels and topsoils are constructed over the tilled soil. Then a layer of drainage stone and pipe-work (the absorption bed) is installed and connected to the pumping station. The sand/gravel is then covered with a geo-textile membrane and finally, topsoil finishes the absorption mound. This final layer of soil is seeded for grass to grow quickly over the mound, preventing erosion problems.No shrubs should be grown on it as their roots mat damage the absorption bed.

Contact WTE Ltd. for details of our design service.