With growing reference by designers, city officials and informed citizens, the term “green infrastructure” is rising into the national vocabulary. Infrastructure is something we experience daily, every time we walk, bike, drive or drink a glass of water. We really can’t survive without it. ‘Green infrastructure’ sometimes comes across as more tangible than ‘sustainable’ technologies. And to paraphrase Kermit the Frog, making infrastructure green isn’t easy. Fortunately, creating green infrastructure is worth the effort.
A common deployment of green infrastructure is through the use of vegetation and soil to manage rainfall where it lands, rather than stuffing it in pipes for disposal elsewhere (and to others’ chagrin). Installing green infrastructure has been the basis for resolving years of U.S. EPA litigation with some 770 cities to reduce combined storm and sanitary sewers spilling untreated filth into waterways in violation of the Clean Water Act. Beyond using vegetation, bioswales and roof gardens, permeable pavement is emerging as a very effective tool for decreasing the volume of stormwater entering combined sewer systems that overload and then bypass the local sanitary waste treatment plant.
Today, many cities are using green infrastructure programs to renovate existing urban infrastructure supporting blocks or entire neighborhoods. The best projects achieve multiple goals. These can be reached with help from permeable interlocking concrete pavement (PICP). A multiplier effect is embedded within the structure of green infrastructure. Here are some multipliers when PICP is used:
Stormwater Management – Many studies have demonstrated that PICP reduces runoff and pollutants by meeting water quality goals through volume reduction, thereby reducing damage to lakes, rivers and beaches. A key PICP use is reducing combined sewer overflows (CSO) in older urban areas and in turn meeting NPDES permit requirements including total maximum daily loads (TMDLs). Any doubts about the effectiveness of PICP in achieving these goals should diminish by reading this issue’s coverage of PICP research at the University of New Hampshire Stormwater Center.
Efficient Water Use – PICP recharges aquifers for water supplies and reduces the need for water importation that has plagued regions and states like California. At the site scale, PICP stores water for urban irrigation and vegetation around buildings while supporting shade tree watering and tree longevity.
Transportation and Safety – The texture of PICP can be used to calm traffic in residential neighborhoods, support wayfinding with colored units that mark parking areas while increasing neighborhood identity and urban design contexts. Other permeable pavements cannot do this.
Energy Efficiency – PICP has been used experimentally with horizontal ground-source heat pumps for building cooling/heating in residential and commercial structures. Light colored paving units can reduce lighting use with reflective surfaces on sidewalks, parking lots and roadways.
Recycling/Reuse – Like regular interlocking concrete pavers, permeable pavers can be reinstated after utility repairs. The newly released LEED v4 provides credits for concrete pavers specified with a minimum 10 percent recycled content, e.g., flyash, silica fume, glass, etc., and materials in the pavement sourced within a 100-mile radius of a project site.
Urban Heat Island – Light-colored concrete paving units can reduce ambient summer temperatures on streets and sidewalks through reflective pavers on roadways. White titanium dioxide coatings can also help reduce the impacts of ozone and photochemical smog.
Education – Signs at PICP projects can educate the public on PICP design and benefits while creating new public expectations from the performance of parking lots, green alleys and streets. Infrastructure projects must now return multiple benefits to the community.
Economic Development – The scale of some infrastructure projects using PICP are such that homeowners or commercial property owners are motivated to reinvest in their properties. The signal from public sector spending on this is “we want you to stay here, invest and grow families and businesses.” Investment begets investment: This cycle maintains or creates new jobs, a centerpiece of community stability and progress.
No other piece of the infrastructure holds as much potential to contribute to green infrastructure as PICP. Fortunately, cities are recognizing this contribution at an unprecedented pace, and ICPI is pleased to respond with the technical resources needed to make each project’s design, construction and maintenance successful. Visit http://www.icpi.org/permeable. You’ll be surprised at what’s there.