Water Technology (3rd edition)
Chapter 22  Household and Small-scale Treatment Systems
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Septic tank  perolation T-test Nick Gray TCD
Soil percolation tests for septic tanks and small-scale treatment systems
Septic tank perolation trial hole Nick Gray TCD
Septic tank P-test trial hole Nick Gray TCD
Two trial holes should be dug each 1200 x 1200mm square and 750mm in depth, with a
smaller hole 300 x 300mm by 400mm in depth in the centre which is used for the
percolation (T) test (right).
A smaller test hole, 300 x 300mm by
400mm in depth, can also be used to
carry out a P-test which measures
lateral dispersion rather than vertical
dispersion as measured by the T-test.
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