Boston Zoning Code Definition of “Permeable Area of Lot”

Permeable Area of Lot. The Lot Area covered by natural ground cover or any material/surface on the ground that allows water to pass through at a rate and quantity equal to or greater than natural ground cover. Surfaces included in the calculation of Permeable Area of Lot include, but are not limited to, vegetative landscapes, such as lawn and trees; vegetated green infrastructure, such as rain gardens and bioswales; porous paving materials, such as porous asphalt and permeable pavers; and other natural materials that achieve the prescribed infiltration rate of 0.17 inches/hour, as referenced in the Massachusetts Stormwater Handbook (Volume 3, Chapter 1), such as mulch and clean washed stone. The calculation of Permeable Area of Lot excludes permeable surfaces (green roofs) and rain capture systems (e.g. blue roofs) located on a roof or elsewhere on or in an above-grade structure.