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

Runoff Reduction Control Measure Fact SheetPorous PavementDesign CriteriaDesign criteria for porous pavement are listed in Table PP-1.Table PP-1. Design Criteria for Porous Pavement*Also see Appendix D for information on calculating runoff reduction credits.Pavement Type/ Parameter CriteriaPervious Concrete (Figure PP-1)Void spaceMinimum 15% throughout materialBase Course With underdrain - 8” minimum of coarse aggregate over 7” minimum sand over 3”minimum coarse aggregate; without underdrain - 12” minimum coarse aggregateLinerImpermeable liner required when Type C or D soils are present; A or B soils typesrequire geotextile filter cloth with 60 to 80 pores per inch.UnderdrainRequired when specified permeability range is not available in native soils. Use agravel trench or perforated pipe embedded in a 6-12-inch layer of crushed rock.Connect to storm drain (not sanitary sewer).Water Barrier The water barrier should be 24 inch wide thick visqueen run down the 12 inchdeep excavation and 12 inch under the drain rock, or use interceptor drain. Checkwith the geotechnical engineer.Modular Block Pavement (Figure PP-2)Void spaceMinimum 20% surface area as open annular spacesBase Course 8” minimum of coarse aggregateLinerSame as pervious concrete.Reinforced Grass Pavement (Figure PP-3)Base Course 10” minimum of compacted sandy gravel mixCobblestone Block Pavement (Figure PP-4)Void space Minimum 8% surface area as open annular spacesBase Course 7” minimum of coarse aggregate over 7” minimum of sand.LinerSame as pervious concrete.Porous Gravel Pavement (Figure PP-5)General With underdrain - 12” minimum of coarse aggregate over 7” minimum sand over 3”minimum coarse aggregate; without underdrain - 14” minimum coarse aggregateLinerSame as pervious concrete.Source: Urban Drainage and Flood Control District. Denver, Colorado*Design criteria may vary by permitting agency; check before proceeding with design. A permeability test will be required to verifysuitability of this technique for the site. A qualified engineer must provide site-specific design specifications for pavement installation.In addition, the manufacturer’s specifications apply.Stormwater Quality Design Manual for the Sacramento and South Placer RegionsMay 2007PP-11