Hydraulic characterization of sinkhole protection filters for highway drainage

Puerto Rico has a large amount of natural sinkholes used in the recollection and discharge of rainwater from highway drainage. The results of this practice are serious periodic flooding problems when the hydraulic capacity of the sinkhole is exceeded, and the potential contamination of the groundwater due to the poor water quality of the runoff discharges.; Protection filter designs, including geotextile layers, have been proposed as a way to mitigate these effects. However, in spite of the high construction cost involved, flooding events are still occurring when the hydraulic capacity of the filter is exceeded due to the accumulation of fine material in the filter bed and the loss of energy buildup.; The functionality of one of the proposed filters was evaluated by using a mathematical model supplemented with experimental data. The model uses the conservation of mass and a kinetic equation to estimate the rate of accumulation of sediments inside the filter and the energy loss through the bed material.; Results show that negative pressures occur at the lower layers of the sand bed and the effects of the geotextile are negligible in all of the cases. The model could be used to establish design parameters and criteria for the removal of the sand bed material before the saturation and degradation of the sinkhole occurs and the filter clogs.