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→Surface Infiltration Rate Testing
* Fine sand (for even contact between Tension infiltrometer and soil surface)}}
* Fine sand (for even contact between Tension infiltrometer and soil surface)}}
For further information regarding soil characteristics, acceptance criteria per LID BMP type and associated testing tools and protocols scroll down to the embedded 2016 guide below.
===Triggers for Follow-Up and Corrective Actions===
{| class="wikitable" style="width: 1275px;"
|+'''Surface infiltration rate – triggers for follow-up and corrective actions by BMP type'''
|-
!<br>'''BMP Type'''
!<br>'''Trigger'''
!<br>'''Follow-up and Corrective Actions'''
|-
|'''[[Bioretention]] / [[Bioswales]] / [[Stormwater Tree Trenches]] / [[Stormwater planters]] and [[Dry swale|Dry swales]] ([[filter media]] bed surface)'''
|
i < 25 mm/h;
KS < 1 x 10-5 cm/s<br>
<br>
i > 203 mm/h;<br>
KS > 0.02 cm/s
|
*When part of an Assumption inspection, issue a stop work order and contact the construction site supervisor, design professionals and property owner or project manager to determine follow-up tasks. Follow-up tasks involve scheduling FIT work to do further testing to determine the affected area and depth and decide on corrective actions.
*Corrective actions may involve removal of any accumulated sediment, mulch or stone cover and plantings and tilling of the top 20 to 30 cm of filter media to eliminate surface crusting or macropores and reduce compaction. *Alternatively, removal and replacement of all or the uppermost 15 cm of filter media with material that meets design specifications may be necessary.
|-
|'''Single Ring Infiltrometer''' (constant or falling head)
|
*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<ref>Klute, A. 1986. Methods of soil analysis, Part I. Physical and mineralogical methods, 2nd edition. Soil
Science Society of America. Madison, WI. https://acsess.onlinelibrary.wiley.com/doi/book/10.2136/sssabookser5.1.2ed</ref>). 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<ref>ASTM International, 2015. Standard Test Method for Surface Infiltration Rate of Permeable Unit Pavement Systems. Book of Standards Volume: 04.05. Published Online: 27 December, 2018. DOI: 10.1520/C1781_C1781M-15. https://www.astm.org/c1781_c1781m-15.html</ref>). For pervious concrete or porous asphalt, follow the procedure provided by ASTM C1701_C1701M – 09 (ASTM International, 2009<ref>ASTM. 2009. Standard Test Method for Infiltration Rate of In Place Pervious Concrete. Book of Standards Volume: 04.02. Published Online: 17 March, 2017. DOI: 10.1520/C1701_C1701M-09. https://www.astm.org/c1701_c1701m-09.html</ref>). <br>
*Accuracy for soil testing is only moderate relative to permeameter methods (ASTM International, 2010)<ref name="example1" />. 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.
|[[File:Single ring.JPG|350px]]
|-
|'''Modified Philip Dunne Infiltrometer''' (falling head)
|
*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)<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.
|[[File:Modified Philip Dunne.PNG|350px]]
|-
|'''Guelph Permeameter with Tension Disk''' (constant head)
|
*The Guelph permeameter (See photo example - Source: Hoskin Scientific Ltd., 2022<ref>Hoskin Scientific Ltd. 2022. Guelph Permeameter Kit. https://www.hoskin.ca/catalog/index.php?main_page=product_info&cPath=1_59_67_3677&products_id=5082</ref>)is another test device for measuring saturated hydraulic conductivity of a soil surface when used with a tension disc attachment. The method is similar to a Tension infiltrometer, but with water being directed to the tension disc from an inner or outer Mariotte reservoir, giving it the capacity to test low and high permeability soils (Soil Moisture Equipment Corp. 1986<ref>Soil Moisture Equipment Corporation. 1986. Guelph permeameter 2800ki operating instructions. Revision 8/86. Santa Barbara, CA.)</ref>. Infiltration rates are calculated from monitoring the water level drop in the reservoir until a steady state is approached.
*Like the Tension infiltrometer method below, tests are run with two applied tensions. Steady state infiltration rates from the two applied tensions are used to calculate a value for saturated hydraulic conductivity. Potentially requires large volume of water and significant length of time for each measurement to reach steady state.
|[[File:Guelph permeameter hoskins.PNG|350px]]
|-
|'''Tension Infiltrometer''' (constant or falling head)
|
*This test involves a porous disc of 10 or 20 cm diameter that is connected to a Marriotte bottle (water reservoir) and a bubbling tower where a negative pressure or tension is set (See photo example - Source: ICT International, n.d.<ref>ICT International. n.d. Determination of Soil Unsaturated Hydraulic Conductivity. https://www.ictinternational.com/casestudies/determination-of-soil-unsaturated-hydraulic-conductivity/</ref>). The porous disc must be placed in contact with the soil surface which usually requires removal of any vegetation and debris. In many cases it is necessary to place a thin layer of fine sand onto the soil surface to provide good contact between the disc and the soil. <br>
*Infiltration rates are measured based on the water level drop in the water reservoir. The steady state infiltration rate into the soil is measured for two applied water pressures. To estimate saturated hydraulic conductivity the pressures need to be slightly negative (i.e., tensions) and it is recommended that successive pressures of -5 cm and -1 cm be used (Erickson et al., 2013)<ref>Erickson, A.J., Weiss, P.T., Gulliver, J.S. 2013. Optimizing Stormwater Treatment Practices: A Handbook of Assessment and Maintenance. New York: Springer. https://experts.umn.edu/en/publications/optimizing-stormwater-treatment-practices-a-handbook-of-assessmen</ref>. The measured steady state infiltration rates are used in equations derived by Reynolds and Elrick (1991)<ref name="example2">Reynolds, W.D. and Elrick, D.E. 1991. Determination of hydraulic conductivity using a tension infiltrometer. Soil Science Society of America Journal. 55(3):633-639. to calculate a value for saturated hydraulic conductivity. https://acsess.onlinelibrary.wiley.com/doi/abs/10.2136/sssaj1991.03615995005500030001x</ref> <br>
*For detailed guidance on how to perform the testing, refer to Reynolds and Elrick (1991)<ref name="example2" />. The Mini-disc Tension infiltrometer (4.5 cm porous disc) uses a falling head method developed by Zhang (1997)<ref>Zhang, R. 1997. Determination of soil sorptivity and hydraulic conductivity form the disk infiltrometer. Soil Science Society of America Journal. 61: 1024-1030. https://acsess.onlinelibrary.wiley.com/doi/abs/10.2136/sssaj1997.03615995006100040005x</ref> to estimate saturated hydraulic conductivity. It is a quicker test to perform than the constant head method but potentially more difficult to achieve adequate contact with the soil surface.
|[[File:Tension infilt data log.PNG|350px]]
|}
For further information regarding soil characteristics, acceptance criteria per LID BMP type, associated testing tools and protocols along with corrective actions, scroll down to the embedded 2016 guide below.
==Natural or Simulated Storm Event Testing==
==Natural or Simulated Storm Event Testing==