Changes

Jump to navigation Jump to search
no edit summary
Line 1: Line 1:  +
[[File:Sandy Bioretention Soil Mix.jpg|thumb|Sandy filter media mix.]]
 +
[[File:Media hand.jpg|thumb|Filter media being used for an online [[bioswale|bioretention swale]] (also of previous, more sandy specification)]]
 
{{TOClimit|2}}
 
{{TOClimit|2}}
[[File:Sandy Bioretention Soil Mix.jpg|thumb|Sandy filter media mix]]
      
It is recommended that the mixture comprises:
 
It is recommended that the mixture comprises:
   
{|Class="wikitable"
 
{|Class="wikitable"
 
|+One of these two blend options
 
|+One of these two blend options
Line 11: Line 11:  
!Blend B: Water quality priority
 
!Blend B: Water quality priority
 
|-
 
|-
|Application
+
!Application
 
|Higher I/P ratio
 
|Higher I/P ratio
 
|
 
|
{Plainlist|1=
+
{{Plainlist|1=
*More diverse [[Bioretention: Plant lists|planting]],
+
*More diverse [[Plant lists|planting]],
*Improved [[metals]] and [[phosphorus]] retention.  
+
*Improved [[heavy metals|metals]] and [[phosphorus]] retention.}}
 
|-
 
|-
|Proportions
+
!Proportions
 
|
 
|
*70 - 80 % coarse [[sand]]  
+
3 parts [[sand]]<br>
*10 - 15 % [[topsoil]]
+
1 part [[Bioretention: Filter media#Organic components|organic soil components]] and [[Bioretention: Filter media#Additives|additives]]
*10 - 15 % [[Bioretention: Filter media#Organic components|organic soil components]] and [[Bioretention: Filter media#Additives|Additives]]
   
|
 
|
*70-80% coarse sand  
+
3 parts [[sand]]<br>
*20-30% organic soil components and additives
+
2 parts [[topsoil]]<br>
 +
1 part sand [[Bioretention: Filter media#Organic components|organic soil components]] and [[Bioretention: Filter media#Additives|additives]]
 +
|-
 +
!
 +
|This mixture may be assumed to have available water storage of [[Bioretention media storage|'''0.4''' unless demonstrated otherwise]]
 +
|This mixture may be assumed to have available water storage of '''0.35''' unless demonstrated otherwise
 
|}
 
|}
   −
 
+
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. 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:
+
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:
 
  −
The final blended product should have the following properties:
      
{|class="wikitable"
 
{|class="wikitable"
Line 41: Line 43:  
|-
 
|-
 
![[Texture]]
 
![[Texture]]
|<20 % fines||Hygrometer
+
|<15 % fines||Hygrometer
 
|-
 
|-
![[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.
 
|-
 
|-
 
![[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>
 
|-
 
|-
 
![[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.  
 
|-
 
|-
 
![[Hydraulic conductivity]]
 
![[Hydraulic conductivity]]
 
|> 25 mm/hr <br> < 250 mm/hr||Falling head or constant head KSAT
 
|> 25 mm/hr <br> < 250 mm/hr||Falling head or constant head KSAT
 
|}
 
|}
 +
 +
Note that grain size distribution does not form part of the recommended acceptance criteria. Whilst this information may be useful in designing blends, the disconnect between hydraulic conductivity and the uniformity of gradation makes it far less important then measuring the hydraulic conductivity directly<ref>CRC for Water Sensitive Cities. (2015). Adoption Guidelines for Stormwater Biofiltration Systems: Appendix C - Guidelines for filter media in stormwater biofiltration systems.</ref>
    
==Sand==
 
==Sand==
Line 61: Line 65:  
{{:Topsoil}}
 
{{:Topsoil}}
 
==Organic components==
 
==Organic components==
<h3>Compost</h3>
+
This is the first big opportunity to manage phosphorus export from a [[bioretention]] or [[stormwater planter]] system. Whilst compost is the most common ingredient, designers working in sensitive watersheds are encouraged to explore the alternatives listed below. Some of these materials may be combined 50:50 with compost to balance the nutrients required by the [[plants]] and the potential for leaching of excess nutrient. 
 +
 +
===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>
 
'''[[Compost|Compost Specifications]]'''
 
'''[[Compost|Compost Specifications]]'''
Line 70: Line 76:  
|+ Organic soil components
 
|+ Organic soil components
 
|-  
 
|-  
!style="background: darkcyan; color: white"|Material
+
!Material
!style="background: darkcyan; color: white"|Benefits
+
!Benefits
!style="background: darkcyan; color: white"|Concerns
+
!Concerns
 
|-
 
|-
!Coconut coir
+
!Coconut coir<ref>Rheaume, A., Hinman, C., and Ahearn, D. (2015). “A Synthesis of Bioretention Research in Pacific Northwest.” Herrera, <http://www.modularwetlands.com/new/wp-content/uploads/2015/11/2-Bioretention-Synthesis-2015-DAhearn.pdf></ref>
 
|Doesn't leach phosphorus||Requires importation
 
|Doesn't leach phosphorus||Requires importation
 
|-
 
|-
 
!Wood chip
 
!Wood chip
|Doesn't leach phosphorus<br>Promotes nitrogen removal from water||unknown
+
|Doesn't leach phosphorus<br>Promotes nitrogen removal from water||-
 
|-
 
|-
 
!Peat Moss
 
!Peat Moss
 
|Doesn't leach phosphorus||Sustainability controversial
 
|Doesn't leach phosphorus||Sustainability controversial
 
|-
 
|-
!Shredded newspaper (see: Pittmoss)
+
!Shredded paper <ref>Urban Drainage and Flood Control District. (2010). “Bioretention.” <http://udfcd.org/criteria-manual/volume-3/t-03-bioretention/> (Mar. 15, 2018).</ref> (see: Pittmoss)
|unknown||unknown
+
|||
 
|}
 
|}
   −
<h3>Coconut coir</h3>
  −
http://www.modularwetlands.com/new/wp-content/uploads/2015/11/2-Bioretention-Synthesis-2015-DAhearn.pdf
     −
<h3>Wood derivatives</h3>
+
===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.
 +
<ref>
    
==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.  
It is recommended that this fraction be taken from the topsoil or the organic portion otherwise; keeping the sand as minimum 65 % by volume.
+
 
 
{{:Additives}}
 
{{:Additives}}
 
----
 
----

Navigation menu