Any experience of borehole deep soakaways?

[boreholedriller1]

Even in areas such as near the Thames. You need to bear in mind that the th e surrounding geology is alluvial deposits, over Terrace Gravels and then t he London Clay. Water within the terrace gravels is in continuity with the Thames, so with the recent rainfall the levels will be high, if not overflo wing. The water level within the Chalk aquifer is at a much lower level and is sealed from the aquifer in the terrace gravels by means of impermeable geology, namely the London Clay, Woolwich and Reading Beds and Thanet Sands . The two aquifers are therefore at different levels and not in direct cont inuity. It would therefore be possible to discharge into the chalk aquifer with the Environment Agency's permission.

[Onetap]

The 'permeable media' that I meant is the permeable chalk strata into which you would be tipping ground water.

The ground water will contain suspended solid particles. I would expect the chalk to become blocked by this over some time, acting as a filter would.

I don't know how you could clear such an accumulation of material.

[boreholedriller1]

ed". An example borehole would be 15 metres of impermeable clay overlying a permeable strata such as chalk.

ich you would be tipping ground water.

the chalk to become blocked by this over some time, acting as a filter wou ld.

A deep bore soakaway is fitted with a syphon head a metre above the base of the attenuation chamber. The soakaway intersects many fractures within the chalk and blocking up with silt is highly unlikely. In installations that are water bearing, the installation can be cleaned out with a borehole pump , but we have never found this to be needed.