In the 1980's, porous asphalt pavement parking lots were used to reduce stormwater runoff from new developments. these early projects are still in service today. With today's concern for water quality, streambed erosion from development runoff, and a need to recharge the vital underground aquifers, many of today's agencies are significantly revising stormwater runoff requirements on developments.
Porous asphalt pavements have been used to address these concerns for over 25 years. The concept is simple, construct stormwater detention basins under the street and parking structures. These basins are designed to collect the stormwater from structures, pavements, and other areas of a development and hold the water until it can percolate into the soil. Porous asphalt pavement is then placed over the top of these basins. These pavements are designed to let the water flow through them and into the detention basin.
Porous asphalt pavement is commonly known as open graded asphalt concrete (OGAC), open graded friction course (OGFC), and permeable asphalt. OGAC/OGFC has been used by state DOTs and local agencies since the 1930's. Most highways constructed in Northern California use OGAC as a final wearing course. The permeable mix allows water to flow through the pavement and drain out the sides. This significantly reduces splash/spray from vehicle traffic and reduces glare from daylight or headlights. Another benefit of OGAC when used on highways is a reduction in vehicle noise.
In California, designers should consider utilizing Caltrans specifications for OGFC (Standard Specifications Section 39) and utilize a PG binder that is stiffer than the binder typically specified in the area. Typically these would be PG 70-10, PG 70-22 PM, or PG 76-22 PM.
CalAPA Porous Pavement Presentation
January 22, 2008
Reigning in the Rain
April 21-25, 2008
Ventura, Newport Beach, Oakland, Santa Cruz
Articles on Porous Pavements
Asphalt: The Right Choice for Porous Pavements
HMAT Sep/Oct 2003
Thinking Green with Porous Asphalt
HMAT May/June 2003
Porous Asphalt Pavement With Recharge Beds: 20 Years and Still Working
Stormwater May/June 2003
Permeable Pavement: What's It Doing on my Street
University of Rhode Island
Novemebr 2005
Information and comparison of porous pavements
Permeable Asphalt Pavement Resources
Overview of the asphalt industry
Additional information on porous asphalt
NAPA: www.hotmix.org
Technical publications on asphalt paving
California Department of Transportation (Caltrans)
Caltrans construction standard specifications
Section 39 for OGAC
Caltrans test methods
CT368 mix design for OGAC
CT205 determination of crushed materials
OGAC & RAC Usage Guides
For the index page to Caltrans Standard Specifications, click HERE. The OGFC specification can be found by opening the "39-100" document.
For the index page to the amendments to the Caltrans Standard Specifictions, click HERE. Open the file "S!-020H." The Section 39 "Amended to Read" can be found on Pages 125-180.
Brief Asphalt Insider newsletter article published April 27, 2009, featuring photos of Disneyland Resort parking lot project utilizing porous pavement.
Short video clip on YouTube of Disneyland Resort porous pavement project during a rainstorm.
