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K = C (D10)2Where K is in cm/s, C = 1, and D10 is the soil particle diameter in mm for which 10% of all soilparticles are finer (smaller) by weight.2. Adjust the measured infiltration rate using the correction factor described in Section 4 toestablish the Design Infiltration Rate in inches per hour (in/hr).
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This method of determining [[design infiltration rate]] is only approved for sandy native soils with d<sub>10</sub> between 0.1 - 2.5 mm (i.e. soils to which the Hazen formula is applicable)<ref>San Francisco Public Utilities Commission. (2017). Determination of Design Infiltration Rates for the Sizing of Infiltration‐based Green Infrastructure Facilities. Retrieved from http://sfwater.org/modules/showdocument.aspx?documentid=9681</ref>. This method is not allowed within areas of fill.
This method of determining [[design infiltration rate]] is only approved for sandy native soils with d<sub>10</sub> between 0.1 - 2.5 mm (i.e. soils to which the Hazen formula is applicable)<ref>San Francisco Public Utilities Commission. (2017). Determination of Design Infiltration Rates for the Sizing of Infiltration‐based Green Infrastructure Facilities. Retrieved from http://sfwater.org/modules/showdocument.aspx?documentid=9681</ref>. This method must not be applied within areas of fill.
==Procedure==
==Procedure==
===Data Analysis===
===Data Analysis===
# As the Soil Grain Size Analysis method is only approved for soils with d<sub>10</sub> between 0.1 and 2.5 millimeters, the Hazen formula <ref>Hazen, A. (1893). Some physical properties of sand and gravel with special reference to the use in filtration. 4th Annual Report, State Board of Health, Boston.</ref> may be used to calculate the soil permeability.
# As the Soil Grain Size Analysis method is only approved for soils with d<sub>10</sub> between 0.1 and 2.5 millimeters, the Hazen formula <ref>Hazen, A. (1893). Some physical properties of sand and gravel with special reference to the use in filtration. 4th Annual Report, State Board of Health, Boston.</ref> may be used to calculate the soil permeability:
# Soil permeability shall be considered to be the measured infiltration rate:
# Soil permeability shall be considered to be the measured infiltration rate:
<math>K=C\cdot {\left (d_{10}\right )^{2}}</math>
{{plainlist|Where:
''d<sub>10</sub>'' = the soil particle diameter for which 10% of all soil particles are finer (smaller) by weight (mm),
''C'' = is a shape fitting parameters (see below), and
''K'' = permeability (mm/hr)
==Safety Correction Factor==
Adjust it!
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