University of New Hampshire Stormwater Center (UNHSC) completed a two year field verification study of a permeable interlocking concrete pavement (PICP) stormwater management system. Monitoring took place from October 2010 through April 2012 on the University of New Hampshire (UNH) main campus in Durham, NH. Volume reduction and subsequently pollutant mass removal exceeds 95% for all pollutants measured including sediment (TSS and SSC), metals (total Zinc - TZn), petroleum hydrocarbons (TPH), and nutrients (TP, ortho-P, TN, TKN, DIN = NO3, N02, NH4). Reductions in effluent concentrations were not observed for these same contaminants. This was presumably due to a concentration of pollutants caused by an exceptional volume reduction. Effluent volumes in any single event never exceeded 5 gallons and peak flows were all less than 1 gallon per minute (with one exception) over the two year monitoring period.
You can download a copy of the final report here