Changes

[[File:Sandy Bioretention Soil Mix.jpg|thumb|Sandy filter media mix.]]

[[File:Sandy Bioretention Soil Mix.jpg|thumb|Sandy filter media mix.]]

{{TOClimit|2}}

{{TOClimit|2}}

!Blend B: Water quality priority

!Blend B: Water quality priority

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|Application

!Application

|Higher I/P ratio

|Higher I/P ratio

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*Improved [[heavy metals|metals]] and [[phosphorus]] retention.}}  

*Improved [[heavy metals|metals]] and [[phosphorus]] retention.}}  

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|Proportions

!Proportions

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*3 parts[[sand]]  

3 parts [[sand]]<br>

*1 part [[Bioretention: Filter media#Organic components|organic soil components]] and [[Bioretention: Filter media#Additives|additives]]

1 part [[Bioretention: Filter media#Organic components|organic soil components]] and [[Bioretention: Filter media#Additives|additives]]

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*3 parts [[sand]]  

3 parts [[sand]]<br>

*2 parts [[topsoil]]  

2 parts [[topsoil]]<br>

*1 part sand [[Bioretention: Filter media#Organic components|organic soil components]] and [[Bioretention: Filter media#Additives|additives]]

1 part sand [[Bioretention: Filter media#Organic components|organic soil components]] and [[Bioretention: Filter media#Additives|additives]]

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Filter media should be obtained premixed from a vendor and meet all municipal, provincial and federal environmental standards. Mixing of sand, topsoil and compost should be done in a manner that preserves topsoil peds.  

Filter media should be obtained premixed from a vendor and meet all municipal, provincial and federal environmental standards.  

The mixture should be free of stones, stumps, roots, or other debris larger than 50 mm diameter. Samples of the filter media should be dried, ground and tested to ensure they meet the following specifications:

Mixing of sand, topsoil and compost should be done in a manner that preserves topsoil peds.  

The mixture should be free of stones, stumps, roots, or other debris larger than 50 mm diameter.

Samples of the filter media should be dried, ground and tested to ensure they meet the following specifications:

{|class="wikitable"

{|class="wikitable"

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![[Texture]]

![[Texture]]

|<20 % fines||Hygrometer

|<15 % fines||Hygrometer

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![[Organic matter]] (OM)

![[Organic matter]] (OM)

|5 - 10 %||ASTM D2974-14, Standard test methods for moisture, ash and organic matter of peat and other organic soils.

|5 - 10 %||ASTM F1647, Standard test methods for organic matter content of athletic field rootzone mixes.

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![[Phosphorus]]

![[Phosphorus]]

|12 - 40 ppm||'Bray' is most common in Ontario. <br>Alternatives include 'Mehlich I or III', or 'Olsen'. <ref>Sawyer JE, Mallarino AP. Differentiating and Understanding the Mehlich 3, Bray, and Olsen Soil Phosphorus Tests 1. http://www.agronext.iastate.edu/soilfertility/info/mnconf11_22_99.pdf. Accessed August 1, 2017.</ref>

|12 - 40 ppm||As measured by the 'Olsen' method for alkaline and calcareous soils (common in Ontario). Alternatives include 'Mehlich I or III', or 'Bray', better suited to acidic to slightly alkaline and non-calcareous soils. Results from these are not directly translatable.<ref>Sawyer JE, Mallarino AP. Differentiating and Understanding the Mehlich 3, Bray, and Olsen Soil Phosphorus Tests 1. http://www.agronext.iastate.edu/soilfertility/info/mnconf11_22_99.pdf. Accessed August 1, 2017.</ref>

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![[Cationic exchange capacity(CEC)]]

![[Cationic exchange capacity(CEC)]]

|10 meq/100 g||ASTM D7503-10, Standard test method for measuring the exchange complex and cation exchange capacity of inorganic fine grained soils.  

|10 meq/100 g||ASTM D7503-10, Standard test methods for measuring the exchange complex and cation exchange capacity of inorganic fine grained soils.  

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![[Hydraulic conductivity]]

![[Hydraulic conductivity]]

{{:Topsoil}}

{{:Topsoil}}

==Organic components==

==Organic components==

===Compost===

===Compost===

Compost is the most widely used organic component. It's use in bioretention facilities is well established and documented.  Low-phosphorus composts should always be sought for use in low impact development facilities, including bioretention. These are typically created from feedstocks including yard, leaf, and wood waste, and must exclude manures, biosolids, and food scraps.<ref>Hurley S, Shrestha P, Cording A. Nutrient Leaching from Compost: Implications for Bioretention and Other Green Stormwater Infrastructure. J Sustain Water Built Environ. 2017;3(3):4017006. doi:10.1061/JSWBAY.0000821.</ref><br>

Compost is the most widely used organic component. It's use in bioretention facilities is well established and documented.  Low-phosphorus composts should always be sought for use in low impact development facilities, including bioretention. These are typically created from feedstocks including yard, leaf, and wood waste, and must exclude manures, biosolids, and food scraps.<ref>Hurley S, Shrestha P, Cording A. Nutrient Leaching from Compost: Implications for Bioretention and Other Green Stormwater Infrastructure. J Sustain Water Built Environ. 2017;3(3):4017006. doi:10.1061/JSWBAY.0000821.</ref><br>

===Wood derivatives===

===Wood derivatives===

https://www.unh.edu/unhsc/sites/default/files/media/unhsc_bsm_spec_2-28-17_0.pdf

The 2017 guidance from New Hampshire specifically rules against the inclusion of compost in their bioretention media.<ref>UNHSC Bioretention Soil Specification. (2017). Retrieved from https://www.unh.edu/unhsc/sites/default/files/media/unhsc_bsm_spec_2-28-17_0.pdf</ref> Instead they recommend sphagnum peat or ''"Shredded wood, wood chips, ground bark, or wood waste; of uniform texture and free of stones, sticks"''. The use of wood chip has been common in New Hampshire for some time, in this 2006 thesis 20 % wood chips (not characterized) were incorporated into all of the test cases to match current practices at the time. <ref>Stone, R. M. (2013). Evaluation and Optimization of Bioretention Design for Nitrogen and Phosphorus Removal. University of New Hampshire. Retrieved from https://www.unh.edu/unhsc/sites/unh.edu.unhsc/files/STONE THESIS FINAL.pdf</ref>

https://www.unh.edu/unhsc/sites/unh.edu.unhsc/files/STONE%20THESIS%20FINAL.pdf

 

https://jbioleng.biomedcentral.com/articles/10.1186/s13036-017-0057-4 (focus on denitrification)

Shredded paper has been tested as an additional source of carbon and as an electron-donor to promote denitrification in a number of successful laboratory and field studies.

==Additives==

==Additives==

Typically these components would comprise 5- 10 % by volume of the filter media mixture.  

Typically these components would make up 5- 10 % by volume of the filter media mixture.  

 

{{:Additives}}

{{:Additives}}

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