Stormwater runoff occurs when rain falls in urban areas.This runoff causes increased pollution in rivers and streams, flash floods and loss of rainwater that could otherwise replenish water tables and aquifers. Pervious concrete has a 25 – 35% void structure in the hardened area. Typically, flow rates of more than 200 litres of water per minute pass through each square metre of previous pavement but flow rates can be substantially higher. This is far more water than is normally generated during most rain storms.

Canasoil drainable surfaces puts rainwater back in the ground where it belongs.

Benefits of Canasoil drainable surface

• Reduces stormwater runoff
• Reduces or eliminates the need for retention ponds
• Reduces impact and cost of stormwater treatment infrastructure and public safety liability
• Replenishes water tables and aquifers
• Allows for more efficient land development
• Minimizes flash flooding, standing water and backflow into the property causing damage
• Prevents warm and polluted water from entering streams and affecting marine habitats
• Mitigates surface pollutants
• Reduces Heat-Island Effect
• May assist in earning points for LEED certified buildings

Sustainability:

Stormwater Management. By allowing water to soak through and infiltrate, pervious paving reduces stormwater flow and pollutant loads. Can contribute to LEED Credit 6.

Minimize Site Distrubance. By integrating paving and drainage, less site area may need to be used to manage stormwater, allowing a more compact site development footprint. May contribute to LEED Credit SS 5.

Local. Materials are usually extracted and manufactured locally. May contribute to LEED Credit M 5.

Recycled content. Some recycled aggregates can replace newly mined gravel. Recycled content can contribute to LEED Credit M 4.

Considerations:

Permeability. Typical flow rates for water through pervious surface are 3 to 8 gallons per sq foot per minute, but can be double that amount if desired.

Compressive Strength. Pervious canasoil can develop compressive strengths in the range of 500 to 4000 psi – suitable for a wide range of applications.

Freeze-Thaw Resistance. Freeze-thaw resistance depends on the saturation level of the voids in the concrete at the time of freezing. In the field, it appears that the rapid draining characteristics of pervious canasoil prevents saturation from occurring. Where substantial moisture and freeze-thaw conditions are anticipated, pervious canasoil should be placed on a 6 to 18-in.-thick layer of drainable rock base such as 1-in. Crushed stone.