Base course

In permeable pavement systems, the base course lies on top of the sub-base reservoir. See the Permeable pavements: Specifications page for base material specifications. The construction steps, key inspection points, and mistakes to avoid for the base course are the same as the guidance given in the storage reservoir section.

However, depending on the municipality and the design, compaction of the base course may be required. For example, the City of Toronto’s Construction Specification for Permeable Interlocking Concrete Pavers (TS 861) details the following steps for base course installation:

1. Place base course aggregate in 100 mm lifts (maximum)
2. Compact each lift with a 9 ton vibratory roller, with two passes in vibratory mode and two passes in static mode, or until there is no visible movement of the aggregate.
3. Use a plate compactor for smaller areas that the vibratory roller cannot reach.

An alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil.

An underlying bed filled with aggregate or other void-forming fill material that temporarily stores stormwater before infiltrating into the native soil or being conveyed by an underdrain pipe.

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.