GBU permeable geotextile for Arborflow tree pits is selected specifically to meet permeability objectives required for GBU Arborflow SuDS tree pits using RootSpace and ArborCell systems. GBUCWMA is used both above and beneath the ArborCell layer. Water entering the tree pit from the road can frequently enter with volume and force, threatening localised erosion within the tree pit, GBUCWMA below the ArborCell helps eliminate the erosive force of the water and permit gentle infiltration into the soil across the entire tree pit. GBUCWMA also supports permeable paving generally used over Arborflow tree pits and prevents paving base from infiltrating the ArborCell layer.