Seven Wessler employees recently attended another successful Indiana Association of Floodplain and Stormwater Management (INAFSM) Conference. The INAFSM Conference always provides its attendees with informative presentations, field trips, and networking opportunities. Green infrastructure continues to be an important topic of discussion. Though many technologies were presented, multiple presentations at INAFSM this year discussed the topic of permeable pavement and the performance results based on application location, maintenance plans, climate, and overall design.
Permeable pavement has been applied in multiple locations throughout Indiana, yet many communities are still unsure of the success of those applications and often speculate if the benefits of permeable pavement is worth the maintenance requirements.
Permeable pavement is specifically designed to allow stormwater to infiltrate through the pavement to an underground storage system or infiltrate into the ground and recharge the water table. There are three main types of permeable pavement: porous asphalt, pervious concrete, and permeable pavers. Porous asphalt and pervious concrete are both structural pavements that are manufactured without fine materials which allows for larger interconnected voids resulting in stormwater infiltration. Permeable pavers consist of structural modular units, typically concrete or brick, that are separated by joints sometimes filled with crushed aggregate. The voids between the pavers provide stormwater infiltration into the subbase below.
Benefits of permeable pavement include volume reduction of stormwater runoff, improved water quality, replenishment of groundwater, hydroplaning resistance, increased visibility from splash reduction, and road salt use reduction during the winter season.
The keys to success of permeable pavements are to insure proper design, materials, installation, and maintenance. The mix design, compaction, and curing processes need to be consistent. The standards of installation vary resulting in the success of some applications and the failure of others. Periodic maintenance is key to the long-term success of permeable pavement applications. The most effective form of maintenance seems to be pressure washing and/or vacuuming with regenerative air sweepers.
The design of permeable pavement depends on the application. Pete Weiss, Ph. D, from Valparaiso University, discussed the application of full-depth permeable pavement shoulders along highways. Permeable pavement shoulders provided up to 40% volume reduction in low permeable soils and retained 85% of total suspended solids. The maintenance of the permeable pavement shoulders included regular visual inspection, periodic infiltration measurements, vacuum sweeping twice a year in areas at a high risk of clogging, and monitoring inspection ports to check the reservoir drainage.
Patrick Kerr, Ph. D, from the City of South Bend, discussed some of the challenges and successes of permeable paver applications in South Bend. The City has used permeable pavers in several projects over the past few years including parking lots, pedestrian areas, residential streets, and urban parking lanes. Often the challenges in permeable paver design and application came from the lack of standards. With each application, the City was able to learn from the shortcomings to provide better specifications and designs for the next installation.
Overall, permeable pavements provide multiple benefits as long as they are designed appropriately for the application, location, climate, and soil type and are adequately maintained. As more permeable pavement applications are constructed and lessons-learned are shared, the design and implementation of this technology will continue to improve. Thanks to the INAFSM conference, we are able to share our ideas, successes, and failures with our colleagues in stormwater management to allow us to continuously grow in our fields and improve the services we provide to the public.
INAFSM Links and Presentations:
- Pervious, Permeable, and Porous Surfaces: Their Relationship to Stormwater Management by Mark Walker, Kuert Concrete, Inc.
- Permeable Pavements in Cold Climates by Pete Weiss, Ph. D, Valparaiso University
- Advancements and Challenges of Stormwater Management Along Highways by Pete Weiss, Ph. D, Valparaiso University
- Challenges and Successes in Permeable Pavement Using Pavers by Patrick Kerr, Ph. D, City of South Bend