Permeable pavement design

Unilock offers a free download of PCSWMM for Permeable Pavers—software developed for use with the U.S. Environmental Protection Agency’s SWMM—to allow planners and designers to simulate the response of permeable pavements in long-term modeling applications.

According to Unilock, performance of a permeable pavement installation is controlled by the infiltration capacity of the permeable pavement, storage capacity of the reservoir in the base, and the infiltration capacity of the underlying soil. The company determined parameters such as the infiltration capacity of the permeable pavement in field and laboratory studies. Additionally, since permeable pavers are used for long-term applications, the program was written for continuous simulations, and accounts for degradation over time and regeneration of infiltration capacity by mechanical means.

However, certain hydrological design conditions must be met, Unilock says. Because of the relatively small areas involved, short computational time steps, such as 1 minute, are required, as are short duration design events (1 hour). Secondly, the reservoir in the pavement sub-base must be properly sized based on its drainage outlet capacity and the porosity of the constituent crushed rock.

More information about design of permeable pavements using interlocking pavers is available from the Interlocking Concrete Pavement Institute.