8,255
edits
Changes
Jump to navigation
Jump to search
mLine 1:
Line 1: − + + + + + + − + Line 14:
Line 19: + Line 33:
Line 39: − +
no edit summary
Percolation test results are not readily translated into field saturated hydraulic conductivity (''K<sub>fs</sub>''). 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>.
[[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 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:
The required calculations have been written into an easy to use spreadsheet, formatted for printing:
{{Clickable button|[[Media:Perc test.xls|Download Percolation test spreadsheet(.xls)]]}}
{{Clickable button|[[Media:Perc test.xlsx|Download Percolation test spreadsheet(.xlsx)]]}}
For reference, the relationship between measured percolation test (''PT'') and field saturated hydraulic conductivity (''K<sub>fs</sub>'') used in the spreadsheet is:
For reference, the relationship between measured percolation test (''PT'') and field saturated hydraulic conductivity (''K<sub>fs</sub>'') used in the spreadsheet is:
==Measurement procedure==
==Measurement procedure==
{{float right|{{#widget:YouTube|id=yum8uiPmfMs}}}}
Adapted from<ref>Registered Onsite Wastewater Professional Program BC, PERCOLATION TEST PROCEDURE & FORM (2016) https://owrp.asttbc.org/wp-content/uploads/2016/11/Percolation-Test-Procedure-and-Form.pdf</ref>.
Adapted from<ref>Registered Onsite Wastewater Professional Program BC, PERCOLATION TEST PROCEDURE & FORM (2016) https://owrp.asttbc.org/wp-content/uploads/2016/11/Percolation-Test-Procedure-and-Form.pdf</ref>.
# Place 5 cm of clean fine gravel in the bottom of the hole. If the sidewalls are likely to collapse, use a paper basket to support the sidewalls.
# Place 5 cm of clean fine gravel in the bottom of the hole. If the sidewalls are likely to collapse, use a paper basket to support the sidewalls.
#Place a piece of white plastic or similar provided with clear marks at 12.5 and 15 cm (5" and 6") from the bottom of the test hole prior to adding the gravel. For greater accuracy a float and pointer arrangement can be set up.
#Place a piece of white plastic or similar provided with clear marks at 12.5 and 15 cm (5" and 6") from the bottom of the test hole prior to adding the gravel. For greater accuracy a float and pointer arrangement can be set up.
# If the soil contains considerable amounts of silt or clay, and certainly for any soil with “clay” as part of the texture description, the test holes should be pre-soaked before proceeding with the test. Pre-soaking is accomplished by keeping the hole filled with water for 4 hours or more. The water should be added carefully and slowly to avoid disturbing the soil (including the sidewall soils). The test should be carried out immediately after pre-soaking;
# If the soil contains considerable amounts of silt or clay, and certainly for any soil with “clay” as part of the [[Soil groups|texture description]], the test holes should be pre-soaked before proceeding with the test. Pre-soaking is accomplished by keeping the hole filled with water for 4 hours or more. The water should be added carefully and slowly to avoid disturbing the soil (including the sidewall soils). The test should be carried out immediately after pre-soaking;
===Making measurements===
===Making measurements===