Lewisburg's Stormwater ordinance for new construction requires that all stormwater be kept on the property except when there is an unusual rain event. Permeable paver systems are environmentally friendly and represent the Best Management Practice for stormwater management. This consists of a geotextile fabric separating the subsoil from a 12” minimum base layer of 2 1/2” crushed rock and 8” of 1” crushed rock. The 3” pavers are bedded on a 2” layer of 3/8” crushed rock and the spaces between the pavers are filled with a 1/4” crushed rock. Stormwater flows through the joints between the pavers and down to the 24” base layer where it is slowly absorbed into the subsoil. This design allows the parking lot to “store” approximately 5” of rain before any water leaves the area. Under-drain pipes are installed to remove excess water when there is a “10-year” storm.
At Montwell Commons, we decided that designing the parking lots with permeable pavers was environmentally the best way to adhere to the Stormwater Ordinance, even though it would cost considerably more than using asphalt paving and building detention ponds to keep stormwater from leaving the property. Since there are very few permeable paver installations in the Lewisburg area, the parking lots serve as a demonstration site where other property owners and developers can see how permeable paver systems function in real life.
There are a number of benefits for using a permeable paver system for parking areas and driveways:
Stormwater management - Runoff from paved surfaces can cause serious environmental damage such as erosion and silt build-up in rivers, lakes and streams. By allowing rain and snowmelt to be absorbed on site, permeable paver systems minimize runoff problems and eliminate surface puddles and local flooding.
Groundwater recharge - With permeable pavers, rain and snowmelt percolate naturally down through the layers of crushed rock to the subsoil where they are slowly absorbed and recharge the aquifer.
Pollution control - Permeable paver systems trap 80% or more of total suspended solids along with salt, oil and other pollutants in the runoff rather than allowing them to wash into caves and streams which degrades the water quality. The crushed rock base and sub-base system act as a built-in filtration device.
To see how the lower parking areas and driveway were constructed, 50 photos of the construction steps are shown on this page.
Subsoil, fabric, sub-
drain, base rock