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*E2396 Test Method for Saturated Water Permeability of Granular Drainage Media [https://www.astm.org/Standards/E2396.htms].
*E2396 Test Method for Saturated Water Permeability of Granular Drainage Media [https://www.astm.org/Standards/E2396.htms].
When these tests are completed, the results should be interpreted in relation to the objectives of the green roof. A product complying with overseas guidelines may not serve the needs of a green roof installed in Ontario. In particular, the FLL guide [http://www.fll.de/shop/english-publications/green-roofing-guideline-2008-file-download.html] recommends green roof media specifications which may not provide optimal stormwater management or vegetation in our region. The green roof media used in Ontario can be classed according to proportion of composted biological material. Some existing installations use materials which comply with FLL guidelines, whilst others use a high proportion of compost.[http://grit.daniels.utoronto.ca/wp-content/uploads/2016/06/Comparisons-of-extensive-green-roof-media-in-Southern-Ontario.pdf]
When these tests are completed, the results should be interpreted in relation to the objectives of the green roof. A product complying with overseas guidelines may not serve the needs of a green roof installed in Ontario. In particular, the FLL guide [http://www.fll.de/shop/english-publications/green-roofing-guideline-2008-file-download.html] recommends green roof media specifications which may not provide optimal stormwater management or vegetation in our region. The green roof media used in Ontario can be classed according to proportion of composted biological material. Some existing installations use materials which comply with FLL guidelines, whilst others use a high proportion of [[compost]].[http://grit.daniels.utoronto.ca/wp-content/uploads/2016/06/Comparisons-of-extensive-green-roof-media-in-Southern-Ontario.pdf]
In many proprietary systems the default option for planting medium will be a granular material with very low organic matter content. However, many companies can arrange for a high organic content alternative to be substituted if requested.
In many proprietary systems the default option for planting medium will be a granular material with very low organic matter content. However, many companies can arrange for a high organic content alternative to be substituted if requested.
#Often lighter weight, even when saturated.
#Often lighter weight, even when saturated.
The disadvantages of a 'high organic' planting medium are:
The disadvantages of a 'high organic' planting medium are:
#Increased [[Water Quality#Phosphorous|phosphorous]] concentration in runoff water, however this may be mitigated by the reduced runoff volume resulting in a lower loading overall,
#Increased [[phosphorus]] concentration in runoff water, however this may be mitigated by the reduced runoff volume resulting in a lower loading overall,
#The lightweight material is more prone to wind erosion, and this should be accounted for in the initial design, alternatives include erosion control blankets, soil tackifiers, or Sedum mats.
#The lightweight material is more prone to wind erosion, and this should be accounted for in the initial design, alternatives include erosion control blankets, soil tackifiers, or Sedum mats.
Increasing the depth of planting medium from 10 cm to 15 cm has been shown to benefit the vegetation[http://www.sciencedirect.com/science/article/pii/S0301479713006051]. Stormwater retention was not improved with this increase in depth[http://ascelibrary.org/doi/abs/10.1061/(ASCE)HE.1943-5584.0001534].
Increasing the depth of planting medium from 10 cm to 15 cm has been shown to benefit the vegetation
[http://www.sciencedirect.com/science/article/pii/S0301479713006051]. Stormwater retention was not improved with this increase in depth <ref>Hill J, Drake J, Sleep B, Margolis L. Influences of Four Extensive Green Roof Design Variables on Stormwater Hydrology. J Hydrol Eng. 2017;22(8):4017019. doi:10.1061/(ASCE)HE.1943-5584.0001534.</ref>.
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[[category:materials]]
[[category:materials]]