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The Maryland 2010 stormwater management regulations and design manual (effective in May, 2010) includes strict provisions on sites that are being redeveloped. Also, the mandate to use Environmental Site Design can be very challenging on infill and ultra-urban sites. Many believe this encourages less redevelopment – and consequently more development of previously undeveloped sites leading to continued sprawl which is not supportive of Maryland’s Smart Growth policies.
The Maryland Association of Counties is holding a forum to discuss these issues. read it here: http://conduitstreet.mdcounties.org/tag/stormwater-management/
Our opinion? We believe some relatively minor changes to the design manual – for instance allowing permeable paving on sites that may not infiltrate – would offer more opportunities for Environmental Site Design on redevelopment sites.
Sustainable Stormwater Management 
what’s the point of permeable paving on sites that can’t infiltrate? That sounds like a recipe for future maintenance headaches…
Verplanck:
All it takes is an underdrain system. Raise it above the invert of the gravel storage and you have whatever groundwater recharge the soil will take (practically all soils will infiltrate to a certain degree) and appropriate drainage through the underdrain system. Add a sand layer above the underdrain and viola!, you have a sand filter system providing filtering for water quality treatment. Regarding maintenance, if the permeable paving system is integrated block, the system can be repaired or maintained without being destroyed – unlike permeable concrete or asphalt.