Something as simple as water from a downspout contributes to a number of unwanted consequences. Roofs and other impervious surfaces alter natural hydrology, increasing the volume of stormwater runoff. This has a variety of impacts including streambank erosion, potholes, unwanted algae from nutrient pollution, bacterial contamination, and flash floods. Fortunately, there are simple, low-cost ways to help decrease the volume of runoff, and minimize the pollutant potential of surface water leaving our properties.
There are many new types of pervious materials that allow water to pass through and percolate back into the soil. Some popular choices are permeable asphalts and pavements, paver stones, and turf blocks. There are now pervious options for almost any application.
What to Know Before You Dig:
Having soil that drains quickly is key to picking the right location on your property for the installation of a pervious hardscape. This can be tested by simply digging a 1-2 foot hole in the ground and filling it with water. If the soil can effectively drain 0.5 – 3.0 inches of water per hour, it can be considered as a potential site for your pervious hardscape. Note: Hard compacted clay-like soils are not suitable substrate for constructing your hardscape as they do not drain water effectively.
On the surface:
Porous pavements are most commonly used on pedestrian walkways, driveways, and parking spaces. There are two types of porous materials that can be laid down on your property, each with equal benefits, and can mold perfectly into any household landscape. The first category of porous pavements are turf blocks or rigid bricks. The physical material is impermeable but has spaces in between their structures to allow collecting water to permeate through into the soil. The second category is pervious pavement. This asphalt-like material is ideal for small parking lots with low speed traffic. Pervious pavement is similar to conventional asphalt, but contains small pore spaces that allow for water to percolate into the soil below.
Below the Hardscape:
Underlying the surface should be highly permeable material to ensure the effectiveness of the pervious hardscape. This can be accomplished in several ways with various types of materials that support the surface and allow for high levels of drainage into the soil.