Mulch

Pine mulch will help hold moisture in the soil

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 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.

---

a top dressing over vegetation beds that provides suppresses weeds and helps retain soil moisture in bioretention cells, stormwater planters and dry swales.

Low Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.

a top dressing over vegetation beds that provides suppresses weeds and helps retain soil moisture in bioretention cells, stormwater planters and dry swales.

(1) The wearing away of the land surface by moving water, wind, ice or other geological agents, including such processes as gravitation creep; (2) Detachment and movement of soil or rock fragments by water, wind, ice or gravity (i.e. Accelerated, geological, gully, natural, rill, sheet, splash, or impact, etc).

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

Soil, sand and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals and cloud the water so that needed sunlight might not reach aquatic plans. Careless farming, mining and building activities will expose sediment materials, allowing them to be washed off the land after rainfalls.

Includes the protection of soil from dislocation by water, wind or other agents.

A broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations.