Construction: large stone and riprap

Riprap serves as a protective layer to: prevent sediment entering the underlying layers and clogging the LID facility, dissipate stormwater energy, and stabilize the terrain and slope.

Construction Steps:

1. Backfill the material from the outside of the LID facility to avoid compaction.
2. Ensure the material is being placed to the elevation and thickness to the design requirements.

Key Inspection Points:

• Arrival of material to the site: material meets specifications as per design, no debris in the aggregate and, if possible, washed or clean stone with little to no fine materials in it.
• Placement: material is backfilled to the right depth and elevation.

Common Mistakes to Avoid:

• Use of wrong material that does not meet design specifications. If there are changes in the material, it must be approved by the supervisor or project manager.
  

Riprap

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.

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 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.