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|'''Double Ring Infiltrometer''' (constant head)

|'''Double Ring Infiltrometer''' (constant head)

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*The double-ring infiltrometer is made of two concentric tubes typically of thin metal or hard plastic, that are both continuously filled with water such that a constant water level is maintained as water infiltrates into the soil (ASTM International, 2005). The rate at which water is added to the centre tube is measured to determine the infiltration rate. For detailed guidance on how to perform the testing, refer to ASTM D3385-09 Standard Test Method for Infiltration Rate of Soils in Field Using Double-Ring Infiltrometer (ASTM International, 2009) and ASTM D5093-15 Standard Test Method for Infiltration Rate of Soils in Field Using Double-Ring Infiltrometer with Sealed-Inner Ring.<br>

*The double-ring infiltrometer (See photo example - Source: TRCA, 2012) is made of two concentric tubes typically of thin metal or hard plastic, that are both continuously filled with water such that a constant water level is maintained as water infiltrates into the soil (ASTM International, 2005). The rate at which water is added to the centre tube is measured to determine the infiltration rate. For detailed guidance on how to perform the testing, refer to ASTM D3385-09 Standard Test Method for Infiltration Rate of Soils in Field Using Double-Ring Infiltrometer (ASTM International, 2009) and ASTM D5093-15 Standard Test Method for Infiltration Rate of Soils in Field Using Double-Ring Infiltrometer with Sealed-Inner Ring.<br>

*Accuracy is only moderate relative to permeameter methods (ASTM International, 2010) and results tend to be biased towards higher values due to lateral flow. Potentially requires large volume of water and significant length of time for each measurement to reach steady state.  

*Accuracy is only moderate relative to permeameter methods (ASTM International, 2010) and results tend to be biased towards higher values due to lateral flow. Potentially requires large volume of water and significant length of time for each measurement to reach steady state.  

|'''Single Ring Infiltrometer''' (constant or falling head)

|'''Single Ring Infiltrometer''' (constant or falling head)

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*Similar to the double-ring infiltrometer, except with only one ring. Can be used to measure the vertical movement of water through a soil or permeable pavement. The standard design is a ring that is 30 cm in diameter and 20 cm tall, driven 5 cm into the soil or sealed to the surface of a permeable pavement and filled with water (Klute, 1986). For detailed guidance on how to perform the testing on permeable interlocking pavers, follow the procedure provided by ASTM C1781_C1781M – 15 (ASTM International, 2015). For pervious concrete or porous asphalt, follow the procedure provided by ASTM C1701_C1701M – 09 (ASTM International, 2009). <br>

*Similar to the double-ring infiltrometer, except with only one ring (See photo example - Source: Werner, 2010<ref>Werner, A. 2010. File:Single ring.JPG. Original upload December 21, 2005. Author: Soil Physics at English Wikipedia. https://commons.wikimedia.org/wiki/File:Single_ring.JPG.</ref>) Can be used to measure the vertical movement of water through a soil or permeable pavement. The standard design is a ring that is 30 cm in diameter and 20 cm tall, driven 5 cm into the soil or sealed to the surface of a permeable pavement and filled with water (Klute, 1986). For detailed guidance on how to perform the testing on permeable interlocking pavers, follow the procedure provided by ASTM C1781_C1781M – 15 (ASTM International, 2015). For pervious concrete or porous asphalt, follow the procedure provided by ASTM C1701_C1701M – 09 (ASTM International, 2009). <br>

*Accuracy for soil testing is only moderate relative to permeameter methods (ASTM International, 2010) and results tend to be biased towards higher values due to lateral flow. Potentially requires large volume of water and significant length of time for each measurement to reach steady state when used for soil testing.  

*Accuracy for soil testing is only moderate relative to permeameter methods (ASTM International, 2010) and results tend to be biased towards higher values due to lateral flow. Potentially requires large volume of water and significant length of time for each measurement to reach steady state when used for soil testing.  

|'''Modified Philip Dunne Infiltrometer''' (falling head)  

|'''Modified Philip Dunne Infiltrometer''' (falling head)  

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*The Modified Philip-Dunne infiltrometer is falling head test device made of an open ended 50 cm long clear plastic cylinder with 2 mm thick walls, a 10 cm inner diameter and graduations, inserted into a machined metal base. Unlike the Philip-Dunne permeameter, which requires digging a borehole (i.e., not a surface infiltration test method), it is inserted 5 cm into the surface of the soil without the need for removing vegetation cover. Water level measurements in the tube can be obtained using the graduations on the side of the cylinder and a stopwatch, or continuously recorded through use of a data logger and pressure transducer installed in a piezometer tube. <br>

*The Modified Philip-Dunne infiltrometer (See photo example - Source: Ahmed et al. 2011<ref>Ahmed, F., Gulliver, J.S. and Nieber, J.L. 2011. Performance of low impact development practices on stormwater pollutant load abatement. https://www.researchgate.net/publication/283326958_Performance_of_Low_Impact_Development_Practices_on_Stormwater_Pollutant_Load_Abatement</ref>) is a falling head test device made of an open ended 50 cm long clear plastic cylinder with 2 mm thick walls, a 10 cm inner diameter and graduations, inserted into a machined metal base. Unlike the Philip-Dunne permeameter, which requires digging a borehole (i.e., not a surface infiltration test method), it is inserted 5 cm into the surface of the soil without the need for removing vegetation cover. Water level measurements in the tube can be obtained using the graduations on the side of the cylinder and a stopwatch, or continuously recorded through use of a data logger and pressure transducer installed in a piezometer tube. <br>

*Measurements of soil moisture (e.g., using a handheld soil moisture probe) are needed before and after each test. Using relationships established by Ahmed and Gulliver (2011), the observed infiltration rate and initial and final soil moisture measurements are used to calculate a value for saturated hydraulic conductivity. A quicker test to perform than constant head tests. Superior to the single-ring infiltrometer falling head test as lateral flow is incorporated into the calculations.  

*Measurements of soil moisture (e.g., using a handheld soil moisture probe) are needed before and after each test. Using relationships established by Ahmed and Gulliver (2011), the observed infiltration rate and initial and final soil moisture measurements are used to calculate a value for saturated hydraulic conductivity. A quicker test to perform than constant head tests. Superior to the single-ring infiltrometer falling head test as lateral flow is incorporated into the calculations.