Road Runoff Water-Quality Mitigation by Permeable Modular Concrete Pavers

Discharge from a 200 m(2) permeable modular concrete paver test section on an atypical 6.0 to 7.4% slope and in an active roadway was monitored concurrently with an adjacent reference conventional asphalt section in Auckland, New Zealand. The permeable modular pavement (PMP) underdrain water quality had consistent total suspended solids (TSS), zinc, and copper event mean concentrations that were statistically less than the reference asphalt runoff. Event mean concentration (EMC) distributions ranged over only a few mu g/L, or mg/L from the PMP underdrain versus more than an order of magnitude for some parameters from the reference asphalt. Runoff volume control by the PMP contributed to substantial pollutant mass loading differences despite clay subsurface soils. PMP joint and bedding material were identified as the likely source of most pollutants in the underdrain discharge that might be avoidable with a construction specification for well-washed materials. A properly designed PMP section would likely provide adequate treatment for an expanded source area. Combined with data from the literature, it is recommended that permeable pavements, in general, be given strong consideration for effective source treatment of urban storm-water runoff. DOI: 10.1061/(ASCE)IR.1943-4774.0000339. (C) 2011 American Society of Civil Engineers.