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

Integrated ApproachIt is also helpful to arrange a meeting with the local permitting agency to get agencyinput at the conceptual design stage; in most jurisdictions, this is referred to as thepre-application meeting.It is equally important that those involved in site planning and design workcollaborate throughout the site design process; that way, stormwater quality featurescan be optimally integrated into the site and project design. This might be facilitatedby periodic meetings of the project team and by routing various designs to thedifferent disciplines for review and comment.Consider the site and its surroundingsGather information about the following site characteristics, which will greatlyinfluence the type of stormwater quality controls used on your project:• Existing natural hydrologic features and natural resources, including anycontiguous natural areas, wetlands, watercourses, seeps, or springs.• Existing site topography, including contours of any slopes of 4% or steeper,general direction of surface drainage, local high or low points or depressions, andany outcrops or other significant geologic features.• Zoning, including requirements for setbacks and open space.• Soil types (including hydrologic soil groups) and depth to groundwater, whichmay determine whether infiltration is a feasible option for managing site runoff.A preliminary determination of infiltration feasibility may be made using maps inhydrology and flood control design manuals published by the local permittingagency. Also, site-specific information (e.g. from boring logs or geotechnicalstudies) may be required by the permitting agency, depending on the site locationand characteristics.• Existing site drainage. For undeveloped sites, determine drainage patterns byinspecting the site and examining topographic maps and survey data. Forpreviously developed sites, locate site drainage and connections to the municipalstorm drain system from a site inspection, municipal storm drain maps, and/orthe approved plans for the existing development (typically on file with the localmunicipality).• Existing vegetative cover and impervious areas, if any.Identify Opportunities and ConstraintsUsing the site features information gathered above, identify the principalopportunities and constraints for stormwater quality management on the site.Opportunities might include existing natural areas, low (depressed) areas, oddlyconfigured or otherwise un-developable parcels, easements, and open space (whichpotentially can double as locations for stormwater quality controls with thepermitting agency’s approval). Also look at elevation differences on the site whichmight provide hydraulic head for structural treatment control measures.Stormwater Quality Design Manual for the Sacramento and South Placer RegionsMay 2007 2-3