Over 50 persons recently gathered in Davis, California, to remove barriers to wider use of permeable pavements.
Led by Dr. John Harvey, Director of the UC Pavement Research Center at UC Davis, experts convened last November to identify barriers to permeable pavements and how to overcome them. The conference began with presentations by industry representatives, plus federal, state, and municipal officials, academics, and consultants. While most participants came from areas within storm water management, others came with a pavements background.
While presentations proceeded, the audience wrote questions for discussion. This resulted in 76 questions covering the topics listed below. The second day of the conference consisted of breakout groups generating answers to these questions. Here are the salient questions and answers. All responses are found at www.ucprc.ucdavis.edu/permPvmt.
Costing & cost decision support—Unlike approaches for traditional pavements, life cycle costs analyses must include off-site benefits. Continued initial and maintenance costs must be monitored and collected.
Material & pavement performance—More pilot projects, specifically street and road shoulder demonstration projects are needed. Pervious concrete and porous asphalt durability needs to be improved.
Education & training—Besides in-service training for design professionals and decision-makers, there needs to be university curriculum on permeable pavements. Can design professional training also include certification? Civil engineers need to learn how to design permeable pavements in saturated subgrades as this isn’t taught in university curriculum. Hence, the reluctance to use permeable pavements. This is a core institutional concern.
Communication among industries and users—Can there be an information clearinghouse?
Project-level design concerns—There is a need for more design details, standard methods for soil investigations, and structural design tables developed from full-scale load testing include hybrid designs. Tested proof of structural performance is needed to raise user confidence. This will promote full-width street applications and convince more municipalities to adopt permeable pavements into their catalogs of standard specs and drawings.
Watershed & flood control design concerns—Permeable pavements have the potential to reduce flooding and contribute to a more resilient infrastructure. What research, modeling, and case studies are needed to demonstrate this? What are the economic benefits? Cities such as Atlanta and New Orleans are using permeable pavement to control flooding, i.e., the road system is also the runoff storage and conveyance system.
Designing for additional benefits & impacts—Permeable pavements have many benefits beyond stormwater management. They need to be quantified and some need to be measured through environmental life cycle assessment analyses.
Construction standards & issues—Continued contractor training and construction QC/QA are essential, as well as refinement of specifications, and adoption into state and local specifications.
Maintenance—Systematic collection of maintenance data and costs is needed, especially on surface cleaning, as well utility repair guidelines and costs.
Asset management—This is an emerging field. There needs to be condition survey tools that include stormwater/infiltration performance as well as structural performance to include permeable pavements in pavement asset management software programs used by municipalities. Standard O&M guides need to be created and standardized.
Funding for research, development, and implementation—Funding sources for quantifying stormwater management have been from industry, municipal, state and federal sources. More research is needed on structural performance and on watershed flood control. Should there be a university center for this?
Planning & development codes—Opportunities abound for updating municipal codes, LID, and complete street guidelines for road agencies. Greater confidence by such agencies in performance and designs for low maintenance will help gain acceptance and reduce stormwater versus road agency bifurcation of interests and priorities. Resilience may be key to getting road agencies to adopt permeable pavements, as stormwater management doesn’t hold a top priority or a compelling interest for adoption by many road agencies. l