Re: Re: Site Assessment and Septic Tank Registration/ Inspection
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There are several factors affecting the disposal of sewage.
The old percolation test was a measure of how permeable the subsoil was.
If it was too permeable, there was a risk of groundwater pollution.
If it was too impermeable, there was a risk of it staying on the surface and not being filtered by the soil and/or “digested” by anaerobic bacteria.
However even where the percolation rate was “just right” [The Goldilocks Standard – I just made that up :)] not much happened outside the grass growing season.
If the temperature fell below circa 10 degrees Celsius, the received wisdom was that the grass stopped growing and not much “digestion” occurred.
Also if there was a high water table during the rainy season or very cold / freezing weather, nothing worked well.
Thus you were left with a bare 6-8 months good use out of the system with 4-6 months poor or no use.
This could sometimes lead to a percolation area becoming saturated with effluent over time.
The fact that this was recognized is implicit in the Reserve Percolation Area requirement.
This allowed another percolation area to be used to allow the first to “recover”.