Stormwater Quality Design Manual (May 2007) - City of Sacramento ...

Runoff Reduction Control Measure Fact SheetPorous PavementDescriptionPorous pavement allows stormwater runoff toinfiltrate into the ground through voids in thepavement materials. There are many types ofporous pavement, including pervious concreteand asphalt, modular block, reinforced grass,cobblestone block and gravel. When properlyinstalled, and in the proper setting, porouspavement can be as functional and durable astraditional surfaces.Siting Considerations• Soil permeability: 0.6-2 in/hr (permeability test required to confirm).• Depth to groundwater: minimum 10 feet below aggregate base.• Grade: 10% maximum.• Loading: pavement material and design must accommodate anticipated load.Vector Considerations• Potential for mosquitoes due to standing water will be greatly reduced or eliminated if the porouspavement is properly designed, constructed, and operated to maintain its infiltration capacity.Advantages• Replaces regular pavement, so does not require additional land on the site.• Can reduce size of downstream stormwater quality treatment measures by reducing the volumerequired to treat.• Allows for tree preservation in areas requiring pavement.• Sometimes more attractive than traditional pavement.Limitations• Generally, not ideal for high usage parking lots and roadways with high traffic loadings.• Do not use on sites with a likelihood of oil, grease or other hazardous spills.• Certain types (e.g., modular block pavement) may not be acceptable to local fire authority.• Porous asphalt will be considered on case by case basis.Maintenance Recommendations (Low to Moderate 1 )• Block pavers with voids filled with sand or sandy loam may require occasional replacement of fillmaterial if infiltration capacity is lost.• All of the hard surfaces will benefit from occasional vacuuming.• Grassed pavements require regular mowing.• Pervious pavements may need to be replaced after several years, depending on the amount of finematerial deposited on the surface.1 Compared to stormwater quality treatment control measures discussed in Chapter 6.Stormwater Quality Design Manual for the Sacramento and South Placer RegionsMay 2007PP-1