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Line 1: − + − This article gives recommendations for aggregate to be used to store water for infiltration. This is usually called 'Clear stone' at aggregate yards. To see an analysis of Ontario Standard Specifications for granular materials, see [[OPS Aggregates]]. For advice on decorative surface aggregates see [[Stone]] − Gravel used for [[underdrains]] in [[bioretention]], [[infiltration trenches]] and [[infiltration chambers|chambers]], and [[exfiltration trenches]] should be 20 OR 50 mm, uniformly-graded, clean (maximum wash loss of 0.5%), crushed angular stone that has a void ratio of 0.4<ref>Porosity of Structural Backfill, Tech Sheet #1, Stormtech, Nov 2012, http://www.stormtech.com/download_files/pdf/techsheet1.pdf accessed 16 October 2017 </ref>.+ + − + + + + + + + Line 12:
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[[File:Clear stone.jpg|thumb|Note the low proportion of fines, the uniform size and angularity of this clear stone sample.]]
[[File:Clear stone.jpg|thumb|Note the uniform size and angularity of this clear stone sample.
Note also that the fragments all appear to have a film of fine particles adhering; this material would be improved by being washed prior to use.]]
This article gives recommendations for aggregate to be used to store water for infiltration. This is usually called 'Clear stone' at aggregate yards.
The clean wash to prevent rapid accumulation of fines from the aggregate particles in the base of the reservoir. The uniform grading and the angularity are important to maintain pore throats and clear voids between particles. (i.e. achieve the void ratio). Porosity and permeability are directly influenced by the size, gradation and angularity of the particles <ref name = Judge>Judge, Aaron, "Measurement of the Hydraulic Conductivity of Gravels Using a Laboratory Permeameter and Silty Sands Using Field Testing with Observation Wells" (2013). Dissertations. 746. http://scholarworks.umass.edu/open_access_dissertations/746</ref>. See [[jar test]] for on-site verification testing protocols.
To see an analysis of Ontario Standard Specifications for granular materials, see [[OPSS aggregates]].
For advice on decorative surface aggregates see [[Stone]]
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Gravel used for [[underdrains]] in [[bioretention]], [[infiltration trenches]] and [[infiltration chambers|chambers]], and [[exfiltration trenches]] should be 20 or 50 mm, uniformly-graded, clean (maximum wash loss of 0.5%), crushed angular stone that has a porosity of 0.4<ref>Porosity of Structural Backfill, Tech Sheet #1, Stormtech, Nov 2012, http://www.stormtech.com/download_files/pdf/techsheet1.pdf accessed 16 October 2017 </ref>.
The clean wash to prevent rapid accumulation of fines from the aggregate particles in the base of the reservoir. The uniform grading and the angularity are important to maintain pore throats and clear voids between particles. (i.e. achieve the porosity). Porosity and permeability are directly influenced by the size, gradation and angularity of the particles <ref name = Judge>Judge, Aaron, "Measurement of the Hydraulic Conductivity of Gravels Using a Laboratory Permeameter and Silty Sands Using Field Testing with Observation Wells" (2013). Dissertations. 746. http://scholarworks.umass.edu/open_access_dissertations/746</ref>. See [[jar test]] for on-site verification testing protocols.
Gravel with structural requirements should also meet the following criteria:
Gravel with structural requirements should also meet the following criteria:
<gallery>
<gallery>
File:Particle void ratio.png|The highest void ratio is found in uniformly graded aggregate, as there are no smaller particles to occupy the inter-particle pores. <ref name = Judge/>
File:Particle void ratio.png|The highest porosity is found in uniformly graded aggregate, as there are no smaller particles to occupy the inter-particle pores. <ref name = Judge/>
File:Particle permeability.png|Higher permeability is found in larger, angular, uniformly graded aggregate. This is due to larger pore sizes and lower tortuosity. <ref name = Judge/>
File:Particle permeability.png|Higher permeability is found in larger, angular, uniformly graded aggregate. This is due to larger pore sizes and lower tortuosity. <ref name = Judge/>
</gallery>
</gallery>
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[[category:materials]]
[[category:materials]]