Alternate Paths and Overflow Structures

Provide an alternate path for stormwater to enter the stone recharge bed
It is a good practice to provide an alternate means for stormwater to enter the stone recharge bed if the pavement surface should ever become plugged or sealed, or for extreme storm events. For pavements without curbs, this can be a two-foot-wide stone edge connected to the bed as shown. For curbed pavements, inlets may be used.

Overflow structures
Porous pavements are not normally designed to store and infiltrate all stormwater from all storms. Therefore, it will be necessary to include some method of outlet control to prevent the water from rising into and over the porous asphalt surface. A common type of outlet control would be an inlet box with an internal weir and low-flow orifice. Examples of overflow devices are shown.

 

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Alternate path: Example of using a stone edge for alternate path to bed and overflow device.

 

 

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Overflow structure: Example of drop inlet for alternate path to bed and overflow device.