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Line 1: − __NOTOC__+ − <pdf>Wentworth-Grain-Size-Chart.pdf</pdf>+ − + − − Many of the physical and chemical properties of soil are affected by texture. − − − ==Native soil classifications== − {{plainlist| − *A – well drained sands and gravel, high infiltration capacity, high leaching potential and low runoff potential; − *B – Moderately drained fine to coarse grained soils, moderate infiltration capacity, moderate leaching potential and moderate runoff potential; − *C – Fine grained, low infiltration capacity, low leaching potential and high runoff potential; − *D – Clay soils, very low infiltration capacity, very low leaching potential and very high runoff potential.}} − − +
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[[File:SoilComposition.png|thumb|Soil Composition]]
This article focuses on the laboratory testing of texture of engineered soils. For information about measuring the properties of the native soils, see [[Design infiltration rate]].
[[File:SoilComposition.png|thumb|SoilComposition]]
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The [[filter media]] component of [[bioretention]], [[swales]] and [[green roofs]] must meet very specific design specifications related to texture in order for the BMP to achieve drainage and water treatment performance targets. If the media texture is too fine (i.e., contains more silt- and clay-sized particles than specified) it may have low permeability and [[Drainage time|drain too slowly]] or retain too much water for excessively long periods of time.
The [[filter media]] component of [[bioretention]], [[swales]] and [[green roofs]] must meet very specific design specifications related to texture in order for the BMP to achieve drainage and water treatment performance targets. If the media texture is too fine (i.e., contains more silt- and clay-sized particles than specified) it may have low permeability and [[Drainage time|drain too slowly]] or retain too much water for excessively long periods of time.
If the media texture is too coarse (i.e., contains more [[sand]] than specified) it will have higher permeability and may drain too quickly to provide adequate treatment of run-off, and may not retain enough water between storm events to sustain healthy vegetation cover.
If the media texture is too coarse (i.e., contains more [[sand]] than specified) it will have higher permeability and may drain too quickly to provide adequate treatment of run-off, and may not retain enough water between storm events to sustain healthy vegetation cover.
==Testing==
==Testing==
Soil texture is most accurately characterized by submitting a representative sample to a soil laboratory for a particle-size distribution (PSD) test. Other commonly used terms for the PSD test by soil laboratories are “Particle-Size Analysis”, “Grain-Size Distribution” and “% Sand, % Silt, % Clay”.
Soil texture is most accurately characterised by submitting a representative sample to a soil laboratory for a particle-size distribution (PSD) test. Other commonly used terms for the PSD test by soil laboratories are “Particle-Size Analysis”, “Grain-Size Distribution” and “% Sand, % Silt, % Clay”.
For bioretention filter media and green roof growing media, “Sand Fraction Analysis” should also be requested.
For bioretention filter media and green roof growing media, “Sand Fraction Analysis” should also be requested.