Research Project Full Title: Water Quality Associated with Permeable Interlocking Concrete Pavers
Principal Investigator(s): Michael Barrett
Full Abstract: Most of the previous studies on porous pavement, whether pervious concrete, porous asphalt, or interlocking concrete pavers, have focused on the water balance and attempted to quantify the reduction in discharge volume that occurs. However, in many areas infiltration capacity is limited and these systems must be installed with underdrains. This paper describes the results of a year-long monitoring program to document the quality of water discharged from the underdrain system of a parking lot with permeable interlocking concrete pavers. The monitoring site is located on the Texas State University campus in San Marcos, Texas. The system was installed with an impermeable liner because of concerns about groundwater contamination in the area; consequently, all the runoff which entered the pavement was discharged through the underdrain. Roof runoff from an adjacent building also discharges to the permeable interlocking concrete pavement, which has a reservoir layer that is 19 inches deep. Monitoring of the water quality demonstrated substantial variation in the concentrations of suspended solids and other common stormwater constituents. Concentrations of TSS and E. coli in the discharge appeared to be positively correlated rainfall intensity with the highest values associated with the most intense events. It appears that a significant reason for this variation is the additional volume contributed by the offsite roof area.