Difference between revisions of "Grain size analysis"
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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 | 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== | ||
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===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! | |||
---- | ---- | ||
Revision as of 15:03, 8 March 2018
This method of determining design infiltration rate is only approved for sandy native soils with d10 between 0.1 - 2.5 mm (i.e. soils to which the Hazen formula is applicable)[1]. This method must not be applied within areas of fill.
Procedure[edit]
- Collect soil samples for each defined soil layer below the bottom of the proposed infiltration facility. Layers must be evaluated to the following depths, depending upon facility type:
- For bioretention facilities, analyze each defined layer below the proposed facility bottom to a depth of at least 3 times the maximum ponding depth, but not less than 1 m.
- For permeable paving, analyze each defined layer below the proposed facility bottom to a depth of at least 3 times the maximum depth of water within the base course, but not less than 1 m.
- For other types of infiltration facilities serving drainage areas up to 4 Ha, analyze each defined layer below the proposed facility bottom to a depth of at least 2.5 times the maximum depth of water in the facility, but not less than 3 m.
- Submit the soil samples for laboratory testing of particle size analysis according to ASTM D422.
Data Analysis[edit]
- As the Soil Grain Size Analysis method is only approved for soils with d10 between 0.1 and 2.5 millimeters, the Hazen formula [2] may be used to calculate the soil permeability:
- Soil permeability shall be considered to be the measured infiltration rate:
{{plainlist|Where: d10 = 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[edit]
Adjust it!
- ↑ 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
- ↑ 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.