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

5 Runoff Reduction Control MeasuresRunoff Reduction PrinciplesThe goal of runoff reduction control measures is tomimic a site's predevelopment balance of runoffand infiltration by using design techniques thatinfiltrate, filter, store, evaporate, and detain runoffclose to its source. Runoff reduction controls areintegrated into site design and can be distributedthroughout the site in a series of small-scale (ormicro-scale) measures. As explained in chapter 1,this approach is one of the key elements in lowimpact development (LID) design.The goal of runoff reductioncontrol measures is to mimica site's predevelopmentbalance of runoff andinfiltration by using designtechniques that infiltrate,filter, store, evaporate, anddetain runoff close to itssource. This approach is oneof the key elements of lowimpact development (LID)design.Runoff reduction controls are typically integratedinto site landscaping (including open space, yards, streetscapes, road medians, andparking lot and sidewalk planters) or into the design of paved and other imperviousareas, such as the building roof. Small-scale runoff controls integrated into theproject design and located close to the source of the water and pollutants can helpreduce the need to convey water and treat it in large, often more costly end-of-pipefacilities located at the bottom of drainage sheds. By reducing the total runoffvolume, these measures can also help alleviate potential downstream habitatdegradation and erosion problems.Although runoff reduction control measures canreduce the size/need for stormwater qualitytreatment, other drainage and flood control designrequirements for the project still apply, asspecified by the local permitting agency.References for drainage and flood controlrequirements are listed in Appendix H.Use of runoff reductioncontrols can reduce theamount of water requiringtreatment on a siteThis chapter addresses the following three basic runoff reduction control strategies:• Replace Conventional Impervious Surfaces with Pervious Surfaces• Disconnect Impervious Surfaces• Plant More Trees To Intercept StormwaterReplace Conventional Impervious Surfaces with Pervious SurfacesThis manual describes several ways to reduce runoff by replacing conventionalimpervious surfaces with pervious ones; the covered approaches are:• Porous Pavement• Alternative Driveways• Green RoofStormwater Quality Design Manual for the Sacramento and South Placer RegionsMay 2007 5-1