# Changes

## Percolation test

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[[File:Perc_test.png|thumb|Schematic of percolation test setup]]{{TOClimit|2}}A percolation test is one way of determining a [[design infiltration rate]]. If a site disturbance must be minimized, this test can be performed in a small augered well. Adding a [[permeameter]] may speed up analysis.  ==Calculations==Percolation test results are not readily cannot be translated into field saturated hydraulic conductivity (''K<sub>fs</sub>'')by simple manuipulation of the units. However, an acceptable approximation can be made by accounting for the soil texture and by making measurements under non-saturated conditions<ref name = 'Reynolds'>Reynolds, W.D., Galloway, K., and Radcliffe, D.E. (2015). "The relationship between perc time and field-saturated hydraulic conductivity for cylindrical test holes.", National Onsite Wastewater Recycling Association (NOWRA) 2015 Onsite Wastewater Mega-Conference, Virginia Beach, VA, USA, November 3-6, 2015</ref>.
The required calculations have been written into an easy to use spreadsheet, formatted for printing:
For reference, the relationship between measured percolation test (''PT'') and field saturated hydraulic conductivity (''K<sub>fs</sub>'') used in the spreadsheet is:
$K_{fs}=\frac{\bar{C_{i}a^{2}}}{PT_{i}\left [ 2\bar{H_{i}^{2}}+\bar{C_{i}}a^{2}+\left ( \frac{2\bar{H_{i}}}{a^*} \right ) \right ]}$
{{Plainlist|1=Where:
*''{{overline|H}}'' = Mean water depth during a test*''a'' = the radius of the test pit *''α*'' = the representative soil soprtive sorptive number, and *''{{overline|C}}'' = is a shape function.}}
Additional details may be found in the original paper<ref name = 'Reynolds'/>.
==Measurement procedure==