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Line 1: + + + + + + + + + − In addition to its aesthetic qualities, mulch is an essential functional component of many LID practices. Mulch assists in − reducing soil erosion, retaining moisture for the plant material, moderating soil − temperature, preventing surface sealing and reducing colonization by opportunistic weed − species. Wood mulch allows for cation exchange in the upper organic − layer of the soil, capturing heavy metals. Regular fresh applications of wood mulch also promotes denitrification, reducing nitrates in impacted surface waters. − − − Mulch should be applied on the surface of bioretention practices at a minimum depth of 75 mm and added to cover bare − areas in order to avoid erosion. Mulch should only be removed and replaced when − contamination has become a concern, when clogging has occurred, or when surface − storage volume has been reduced. − − − Avoid the use of [[Stone|stone]] as a cover for vegetated practices. While stone is a low − maintenance surface treatment, it hinders the addition of plant matter and formation of − topsoil and does not provide the same treatment benefits as mulch. Also, − the stone can be problematic for maintenance if it migrates into the soil. − − − The use of landscape fabric is a common method of reducing weed species in many − landscapes. However, because landscape fabric is likely to become clogged with − sediment in an LID facility, it is not recommended. − − − Shredded hardwood mulch is generally recommended for LID facilities. Its fibrous texture knits together somewhat; providing limited erosion control. In areas with particularly high flow (e.g. around inlets) inorganic mulch or coarse decorative aggregate is recommended instead, as these will not float. All organic mulches have the potential to float and migrate in surface flow after a previously dry period. <ref> Simcock, R and Dando, J. 2013. Mulch specification for stormwater bioretention devices. Prepared by Landcare Research New Zealand Ltd for Auckland Council. Auckland Council technical report, TR2013/056 </ref> − <references />
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[[File:Wood chip mulch.jpg|thumb|Pine mulch will help hold moisture in the soil]]
[[File:Wood chip mulch.jpg|thumb|Pine mulch will help hold moisture in the soil]]
*Mulch is considered to be an normal finishing touch to many types of formal landscaping. Maintaining mulch application can help increase aesthetic value of LID BMPs.
*As in other landscaping applications, the mulch helps to preserve soil moisture for plant survival, and suppresses weed growth.
*Mulch can also help to maintain the organic matter content of underlying filter media, which provides cation exchange capacity for pollutant removal.
*Regular fresh applications of wood mulch can also promote denitrification, reducing nitrates in impacted surface waters.
*Mulch should be applied on the surface of the BMP in a layer of 75 -100 mm.
*Double-shredded hardwood or softwood mulch is recommended for LID facilities. Its fibrous texture knits together somewhat; providing limited erosion control.
*In areas with particularly high flow (e.g. around [[inlets]] and [[forebays]]) coarse decorative aggregate or [[stone]] is recommended to better dissipate energy and protect it from erosion.
*This advice also holds for [[stormwater planters]], which often experience concentrated flow from a [[downspout disconnection| roof downspout or drain]].
*All organic mulches have the potential to float and migrate in surface flow, particularly after a previously dry period. <ref> Simcock, R and Dando, J. 2013. Mulch specification for stormwater bioretention devices. Prepared by Landcare Research New Zealand Ltd for Auckland Council. Auckland Council technical report, TR2013/056 </ref>
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[[Category:Materials]]
[[Category:Materials]]
[[Category:Green infrastructure]]
[[Category:Green infrastructure]]