Grey Paving Slabs

Permeable joint pavers may be impermeable bricks, cobbles, natural stone, or modular unit concrete pavers with permeable joints to allow runoff to percolate to subsurface layers. Where soil permeability is low, an under drain system connected to the storm drain system may be needed. Areas of turf block may be considered “self-treating areas,” and may drain directly to the storm drain system if they do not receive runoff from impervious areas, as allowed by the municipality. Turf block and unit pavers are considered site design measures, and heir use can help reduce the size of treatment measures, by infiltrating or temporarily storing runoff, but they are not treatment measures.