What is pervious concrete?
Pervious concrete pavement is a durable concrete with a low/no fines mix design. This mix design allows for a 15-25% void structure, which will allow 300-1100 inches of rain per hour to pass through it. The flow of water and air through the slab makes it an important element in the growing sustainable construction movement.
Pervious pavement allows infiltration of stormwater into subsurface soil layers and drastically reduces the volume and rate of stormwater runoff. For this reason, it is considered an effective on-site stormwater management tool. Runoff in urbanized watersheds is caused by impervious surfaces such as roads and parking lots. These surfaces are covered with sediment, oil and grease from cars, and any other pollutants spilled or dumped on them. When it rains these pollutants are picked up by the runoff, taken to the nearest storm drain, and dumped in its receiving waterbody. The larger the impervious surface area, the quicker the runoff will travel and the more power it has to pick up and transport pollutants to nearby waterbodies. Pervious pavement can significantly reduce this problem.
The U.S. Environmental Protection Agency lists pervious concrete pavement as a best management practice for its positive impact with water-pollution control, storm water management, safety, reducing the negative impact of urban heat islands, and for allowing trees and other plant life to flourish even in areas of intensive land development.
The US Green Building Council recommends pervious concrete for achieving high levels of on-site storm water dispersal, keeping run-off out of the storm drains and rivers.
Simply put, the use of pervious concrete allows Mother Nature to do her job. When it rains, the rain is supposed to go into the ground be cleansed and recharge aquifers and not discharged into man made sewer systems or overflow creeks and rivers and cause flooding.
Slipping and sliding are virtually eliminated with pervious concrete. Pervious concrete is inherently resistant to freeze-thaw damage and is gaining recognition in northern climates for its snow-handling characteristics. As snow melts on pervious concrete, it immediately passes through the pavement reducing the safety concerns associated with adverse weather.
Effective Land Use
Pervious Concrete can reduce the need for retention basins and expensive under ground storage retention systems, thereby allowing for more effective land use. By reducing the size of the retention basins the developer can be more profitable increasing the value of the project by utilizing more land.
Conventional impervious pavements, particularly parking lots and streets, collect oil, anti-freeze, and other automobile fluids that can be washed into streams, rivers, lakes, and oceans during rains. Drainscape™ – Pervious Concrete porous pavement eliminates water pollution through natural biological processes. As water infiltrates the soil beneath the pavement, larger pollutants are filtered out and microorganisms break down pollutants until they are inert.
Pervious concrete can be designed and installed for use in commercial parking areas to manage stormwater in a cost effective way. Installing a pavement that manages both truck loading and stormwater runoff can reduce both the initial cost of development as well as the long term maintenance cost of the facility. See our photos of the more than 1.3 million yards or pervious concrete installed for the Chinese Olympics directed by our friend Dave Mitchell of Bunyon USA.
Pervious concrete provides a stable, wheelchair-friendly environment for any application. Parking lots can be built flat so that you don’t have to move rainwater from a high spot to a collection facility.
Pervious concrete parking lots or sidewalks alongside a creek, stream or river can help eliminate heated run-off into highly sensitive waterways that you would find with asphalt in addition to the polycylic aromatic hydrocarbons that can poison the water.
Urban areas are often times up to 8 degrees F warmer than the surrounding rural areas, creating “urban heat islands” due to heat absorbing pavements and roofs. Using thermal imagery, NASA photos shows dark pavements (red in photo) in excess of 120 degrees F. Cooler parking surfaces resulting cooler ambient air temperatures and reduce the need for air conditioning, saving energy and reducing power plant emissions. The light color (high albedo) of pervious concrete reflects thermal heat while the open void structure allows the earth’s cooler temperatures from below to cool the pavement. (see photos on our photo page)
Leadership in Energy and Environmental Design (LEED®) is a point rating system devised by the U.S. Green Building Council (USGBC). This credit-based system allows projects to earn points for environmentally friendly actions taken during the construction and use of a building. Using pervious concrete can increase the number of points awarded to a building in the LEED® system.
Trucks and Buses
Pervious concrete can be designed and installed for use in commercial parking areas to manage stormwater in a cost effective way. Installing a pavement that manages both truck loading and stormwater runoff can reduce both the initial cost of development as well as the long term maintenance cost of the facility.