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

Runoff Reduction Fact SheetDisconnected PavementDescriptionDisconnected pavement is any impervious pavementdesigned to sheet flow runoff over adjoiningvegetated areas or porous pavement before it reachesthe storm drain system. As the runoff slows andtravels though vegetation or over a porous surface,water is infiltrated into the soil with some pollutantremoval through filtration.Divided sidewalks in a new residential subdivision are oneform of disconnected pavement. Photo: ECORP ConsultingIt is recommended that you read the PorousPavement Fact Sheet before using this one. Also,Alternative Driveway Design, the next fact sheet inthe series, is a technique which employs principlesfrom this and the Porous Pavement fact sheet.Siting Considerations• Soils: Appropriate for all soil types but porous pavement requires an underdrain for soil types Cand D.• Grade: 10% maximum.• Traffic loading: Select and design surface material with consideration of anticipated load.Vector Considerations• Potential for mosquitoes due to standing water in vegetated features will be greatly reduced oreliminated if the feature is properly designed, constructed, and maintained to ensure completedrainage.Advantages• Takes advantage of already-required landscape areas; no additional space required.• Can reduce size of downstream stormwater quality treatment measures by reducing the volumerequired to treat.• Allows for tree preservation in areas requiring pavement.• Vegetated areas provide green space. Combination of impervious and porous pavement can bemore attractive than traditional installation.Limitations• Do not use on sites with a likelihood of oil, grease or other hazardous spills.• Water barrier will be required where porous material abuts regular asphalt/concrete pavement andthere is concern about water infiltrating the regular pavement subbase.Maintenance Recommendations (Low to Moderate 1 )• See inspection and maintenance recommendations in the Porous Pavement fact sheet.1 As compared to treatment control measures, presented in Chapter 6.Stormwater Quality Design Manual for the Sacramento and South Placer RegionsMay 2007DP-1