Berkeley's First Permeable Street Renews Old Roadway
Allston Way Transformed With Permeable Pavers
The first curb-to-curb permeable street in the Bay Area not only provides a safe and beautiful transportation route in the City of Berkeley, but also infiltrates stormwater, filters pollutants, reduces runoff and improves the health of surrounding trees. Driven by scientific analysis, in-depth research and exhaustive planning, a section of Allston Way was transformed from a deteriorated asphalt surface into a 29,000 square-foot environmentally friendly permeable interlocking concrete pavement (PICP) roadway made of Eco-Priora pavers from Pavestone.
Before the first pavers were installed by European Paver Designs (EPD), concerns from city engineers and arborists about the excavation had to be addressed. The project designers, AECOM and Applied Research Associates, Inc., collaborated on a solution that reduced the excavation depth about one foot by placing an 8" layer of high density polyethylene cellular confinement filled with aggregate as part of the subbase. This approach created a healthy co-existence between the new paver surface and the existing underground utilities and trees along street. In addition, a system of berms and sub-drains within the pavement manages water entering the pavement to maximize infiltration into the subgrade.
During the six-month, two-phase project, seven-man crews installed Eco-Priora pavers, which feature an interlocking joint and a micro-chamfered top edge profile that generates an initial average permeability flow rates of more than 100 inches per hour. Custom yellow and white pavers were installed to create a bold contrast with the darker reddish orange and charcoal pavers so driving lanes, pedestrian crossings and other required roadway markings are permanent and do not require restriping. According to Randy Hays, CEO of EPD, the two-phase installation approach allowed for some give-and-take with the location of the stripes to accommodate any last minute shifts in alignment.
The expert installation, which featured quarter-inch joint and interlocking spacer bars, created an extremely smooth surface for bicyclists and skateboarders to safely enjoy. "In fact, the permeable paver surface is likely safer for cyclist to traverse in wet conditions because it prevents standing water," according to Don Irby, P.E., supervising civil engineer with the City of Berkeley Public Works Department. An initial stormwater monitoring report found that Allston Way reduced 94 percent of runoff during a storm that produced 1.75" of rain over a 19-hour period.
The success of the project helps validate the value of PICP systems for municipalities and offers a blueprint for renewing streets with tangible long-term cost, maintenance and environmental benefits. "The City of Berkeley is really committed to the environmental aspects of construction," said Hays. "Sustainability in the construction industry, especially with regard to water conservation, is very important. Building streets that actually return water to an underground system is a pretty cool thing.
AECOM - Design
Applied Research Associates, Inc. - Design
City of Berkeley Public Works Department - Civil Engineering
European Paver Designs - Installation