455.c11 Impermeable surface coverage

Sets maximum impervious cover as 20% of the site area, or 10% less than the maximum allowed for sites within 200 feet of wetland buffers, in addition to the maximum lot building coverage.

Defines impermeable surfaces to include pools and stormwater management facilities. Allows use of permeable pavement for parking.

(11) Impermeable surface coverage.
a. Impermeable surfaces. For the purposes of calculating the amount of impermeable surface coverage, impermeable surfaces shall include all roads, driveways, parking areas, buildings, decking, rooftop landscapes and other impermeable construction covering the natural landscape. Swimming pool surface water areas for pools which discharge to the storm drainage system shall also be included. Water quality and detention basins, swales, and conveyances for drainage purposes only shall be calculated as impervious cover.
b. Amount permitted. The maximum amount of the site that may be covered by an impermeable surface shall be determined by adding 20 percent of the site area to the maximum percent of lot building coverage established in schedules in sections 19-145 and 19-146, as applicable, of the zoning ordinance. For developments located near (within 200 feet of surface waters which are sensitive to runoff impacts, or for any developments from which runoff is discharged into any wetland or coastal feature, as defined by the state department of environmental management or the RI CRMC, the DPR committee may require a reduction of up to ten percent of the maximum allowable area of impermeable surface in order to mitigate the potential impact to the surface waters or wetland system. For developments located near wetlands or coastal features, compliance with requirements imposed by the DPR committee shall not remove the need to obtain appropriate state or federal approvals and to comply with any associated conditions.
c. Design. Applicants shall integrate the location of permeable surfaces with the overall drainage plan for the site. Natural buffer strips should be maintained adjacent to surface waters. Where this is not possible, vegetative filter strips, using seed mixtures recommended for this purpose and which require minimal or no fertilization should be used.
d. Parking areas. For developments located near surface waters, or for any developments from which runoff is discharged into any wetland, the DPR committee may permit the use of permeable paving materials for surfacing parking areas, provided adequate provisions have been made for delineation of parking spaces and for maintenance. It is the intent of this section that permeable surface areas shall be landscaped, and use of permeable paving materials for parking areas shall be permitted only where warranted by water quality and drainage enhancement considerations.
Chapter 19 Zoning,
Article VIII Development Plan Review,
Section 19-455 Drainage/erosion standards,
c) Drainage standards,
11) Impermeable surface coverage.
Last Accessed: 2010-05-13
Additional Information
Zoning Section 19-1. Definitions: Defines Useable lot area to exclude wetlands, slopes >20%, ledge, flood hazard areas and other constraints that preclude conventional development from the calculation of lot building cover. The definition of Lot building coverage excludes unusable lot area, including swimming pools, from the calculation of maximum lot building cover. Impermeable or impervious cover is not included in this list of definitions.