From LID SWM Planning and Design Guide
Jump to navigation Jump to search
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 roof downspout or drain.
  • All organic mulches have the potential to float and migrate in surface flow, particularly after a previously dry period. [1]

  1. 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