Water Quality Improvement

The slow percolation of contaminated runoff into the pavement through a porous aggregate layer to an outlet substantially slows water movements, provides the possibility of filtration and allows water to pass by a large surface area of stone. By these means the water drops the suspended, fine, solids that it is carrying into the pore space of the pavement layers. The contaminants tend to adhere to the surfaces of the porous material’s particles — particularly to the fine fraction as it provides the largest area of fines. Hydrocarbon contaminants also tend to be sorbed to the solids. For these reasons the water that leaves the pavement is substantially