Changes

All designs require an overflow outlet connected to a storm sewer with capacity to convey larger storms. This is normally achieved with a catch basin outlet, but water may also be directed to a downstream practice (e.g. bioretention, swale). Another option is a gravel diaphragm or trench along the downgradient edge of the pavement that drains to the storage reservoir below.

All designs require an overflow outlet connected to a storm sewer with capacity to convey larger storms. This is normally achieved with a catch basin outlet, but water may also be directed to a downstream practice (e.g. bioretention, swale). Another option is a gravel diaphragm or trench along the downgradient edge of the pavement that drains to the storage reservoir below.

The diagram to the left is an example of a porous asphalt system with overflow edge draining to a reservoir. A flush curb extending into the base may be required as an edge restraint for some permeable pavement types.  Decorative stone is lined with a geotextile to prevent migration of fine sediment into the pavement base and facilitate maintenance.

The diagram to the left is an example of a porous asphalt system with overflow edge draining to a reservoir.<ref>Pennsylvania Department of Environmental Protection (PDEP). 2006.

Pennsylvania Stormwater Best Management Practices Manual. Prepared by Cahill Associates Inc., Harrisburg, PA.</ref> A flush curb extending into the base may be required as an edge restraint for some permeable pavement types.  Decorative stone is lined with a geotextile to prevent migration of fine sediment into the pavement base and facilitate maintenance.

===Finish course===

===Finish course===