Perculation test - Sandy soil problem

[SimonTown]

Hi,

I'm preparing to run a perculation test prior to installing a drainage field for my septic tank, but have run into a problem.

I've dug down to the invert point approx. 600mmx600mm and am now digging a futher 250mm deeper, 300mm x 300mm however the soil at this depth is almost pure sand, and drops back into the hole even without adding any water to do the test.

My question is how to get around this? I've constructed shuttering, but am concerned that this will effect the results by limiting the drainage to the floor of the box only? I could drill holes in the sides of the shuttering to limit this effect, but would like some professional advice?


Thanks


Simon.

[Tony McC]

If you are on sand, it's fairly safe to assume the percolation won't be a worry!

[SimonTown]

Ok, is there a minimum length for the land drain for say four people, or would a ordinary soakaway do the trick?

Thanks for the advice.


Regards


Simon

[Tony McC]

Dispersal systems, which includes some forms of land drains and all soakways, are designed to cope with the anticipated maximum input from the total surface area drained, not by the number of people in the vicinity.

A soakaway should be the simplest answer.

[SimonTown]

Thanks,

Sorry, perhaps I wasn't clear the land drain/soakaway is to remove excess liquor from a septic tank, hence the no of people rather than area.

Regards



Simon

[Tony McC]

Aaah - then the land drain is a leach field! Do you have an outflow prediction?

[SimonTown]

Hi,

The leech field will need to service 4 people, with frequent use of modern water greedy appliances! I was planning to do the perc test to estimate required floor area required. Hence the problem with the sandy soil dropping back into 300mm x 300mm.

Thanks Simon