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*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>
 
*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>
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*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)<ref>Ahmed, F. and Gulliver, J.S. 2011. User’s manual for the MPD infiltrometer. St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN. https://conservancy.umn.edu/bitstream/handle/11299/122987/Ahmed-Gulliver-Nieber%20%282011%29%20-%20SAFL%20PR560.pdf?sequence=1&isAllowed=y</ref>, 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.  
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*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)<ref>Ahmed, F. and Gulliver, J.S. 2011. User’s manual for the MPD infiltrometer. St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN. https://conservancy.umn.edu/bitstream/handle/11299/122987/Ahmed-Gulliver-Nieber%20%282011%29%20-%20SAFL%20PR560.pdf?sequence=1&isAllowed=y</ref>, 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. For detailed guidance on how to perform the testing, refer to ASTM D8152 Standard Practice for Measuring Field Infiltration Rate and Calculating Field Hydraulic Conductivity Using the Modified Philip Dunne Infiltrometer Test (ASTM International, 2022<ref>ASTM International. 2022. Standard Practice for Measuring Field Infiltration Rate and Calculating Field Hydraulic Conductivity Using the Modified Philip Dunne Infiltrometer Test. Book of Standards Volume: 04.09. Published Online:  28 July, 2022. DOI: 10.1520/D8152-18. https://www.astm.org/d8152-18.html</ref>)
 
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