Opening the Skies

2017 Issue 4

A recent conference identified barriers to adoption of permeable pavements and ways to overcome them

by David R. Smith


Opening the Skies

I think this is a first. The University of California Pavement Research Center and Institute for Sustainable Infrastructure hosted a Permeable Pavements Road Map Conference, Nov. 14–15 in downtown Davis, CA. The event was sponsored by the ICPI Foundation for Education & Research, the National Ready Mix Concrete Association, the National Asphalt Pavement Association and Tonji University in China.

About 50 participants gathered, representing federal, state and municipal agencies that look after pavements or manage stormwater, as well as several stormwater and pavement consultants and academics. Orchestrated by Professor John Harvey, who directs the UC Pavement Research Center in Davis, the conference included presentations on technical, economic, political and social aspects of permeable pavements. During the presentations, the group was asked to generate questions to consider the following morning in breakout groups. Seventy-six questions were generated by the group that fell into the following subject headings:

  • Costing & cost decision support
  • Material & pavement performance
  • Education & training
  • Communication
  • Project-level design issues
  • Watershed & flood control design issues
  • Designing for additional benefits & impacts
  • Construction standards & issues
  • Maintenance
  • Asset management
  • Funding for research, development & implementation
  • Planning & development codes

These topics were discussed among the groups and some solutions brainstormed. The breakouts reconvened to present their observations and possible solutions. We expect a report in the coming months.

Some of issues that rose to the top of the discussions:

There are disparate sources of information and documented experiences on permeable pavements. There needs to be an information clearinghouse for permeable pavements to capture and coordinate information. Where this might occur (e.g., ASCE, Water Environment Federation, the Institute for Sustainable Infrastructure, a university, etc.) needs to be decided. While the permeable pavement industries have taken leadership in design guidelines, specifications and development of test methods and guidelines through ASCE, ASTM and ACI standards, there needs to be a national information hub stormwater and pavement folks can use to exchange information.

Streets serve multiple economic, environmental health and social objectives within a city. Permeable pavement advocates will be more successful when their technologies are positioned to enhance a broader set of design objectives besides reducing runoff and combined sewer overflows. This includes safety, traffic calming and providing a social platform for public events and businesses.

Green infrastructure projects, generally implemented to reduce combined sewer overflows, often include permeable pavements. These projects are usually administered by public water or sewer utilities. They are most often not the folks responsible for municipal roads with city administrations. Full-width permeable pavements, or a transition to a permeable road infrastructure, will occur when public works officials embrace permeable pavements. They must be given control soon.

One gap or barrier to such officials embracing permeable pavements is the inability (and resulting unwillingness) of engineers to design pavements where soils are saturated much of the time. That is outside their education and zone of experience. There needs to be a shift in civil engineering training that develops instructional curriculum addressing this as a prerequisite to learning how to design permeable pavements.

Finally, it is this editor’s opinion that the reduction of pollutants alone sometimes hampers the expansion of permeable pavements. While federal and state pollutant reduction laws have spawned the permeable pavement industry, they can become a barrier to societal institutionalization of permeable pavements. Most states only mandate pollutant reduction to fulfill their permitting authority under the National Pollutant Discharge Elimination System. There are a handful of states that have mandated volume reduction and offer pollution reduction credits (approval) precisely because volume reduction means a corresponding reduction of pollutants. Such states have seen enormous growth of permeable pavements. States that only mandate pollutant reduction will need to see laws changed to include volume reductions at levels that qualify for pollutant reductions. When that happens, the skies will open and permeable pavements will reap the harvest.