Chevy Chase Village takes a very strict approach to rainwater management by applying the rules to home additions of any size. The problem the regulations are attempting to resolve is that buildings take away permeable surface area on your property where water would naturally percolate down through the soil and be slowly released into the ground water system.
When rain falls on your roof, water is directed via downspouts and pipes into storm sewers. That results in high velocity volumes of water barreling through the system. That's not good. Over many years, all that fast moving water has unmercifully gutted and eroded our beautiful stream valleys (Rock Creek, Sligo Creek) and tributaries to the Potomac and Anacostia Rivers. Further down stream the problem gets worse. All that soil erosion and polluted run off creates vast "dead zones" (oxygen depleted areas) in the Chesapeake Bay.
So... rain water from my roof top is suffocating oyster beds? Well, of course there are other culprits (run-off from roadways, sidewalks, parking lots, etc etc) but, yes, buildings and homes are a contributing factor. It's a big problem--especially since the transportation infrastructure was originally designed to move water as rapidly as possible to ..... someplace else.
In the Village of Chevy Chase, someplace else is now designated as your yard. So, as we planned a modest home addition for a new kitchen and family room on Hesketh Street, we were obliged to include a documented water management plan in our home addition planning process to meet County regulations.
Our client had two water management solutions to choose from: