Drainage Design Manual - the City of San Luis Obispo

3.6.4 Preference for Vegetative and Biotechnical Approaches to Bank Stabilization• The Section 6.0 design procedures require that the project designer give firstconsideration to the use of a vegetative or Biotechnical (also referred to as soilbioengineering) approach to bank stabilization. Structural approaches are discouraged.This is consistent with the SLO Creek Stream Management and Maintenance Programdocument.3.6.5 Limitations On Use of Structural Approaches to Bank Stabilization• Structural approaches to bank protection will only be considered at highly constrainedsites; those sites with limited top of bank work area, or that present unusual geotechnicalbank instabilities and/or that have high velocities and bank shear forces that preclude theuse of vegetative and biotechnical approaches to bank stabilization. The amount of landavailable at top of bank and the need to protect valuable bank top improvements andinfrastructure also needs to be factored into the analysis and selection of the appropriatestabilization design. This provides a basis to consider what is at risk at top of bank. Thepresence of these design constraints must be demonstrated in a Concept Plan and DesignReport that the City or County will require the applicant for a grading and/or buildingpermit submit for each project impacting the stream corridor.• The use of purely structural and hard armoring approaches to bank stabilization withinthe SLO watershed is to be avoided, except where justified by unusual site constraints.Private property owners along the creek are advised that it will be difficult to obtain thenecessary local, state, and federal permits for purely structural approaches to bankstabilization, particularly gabion, sheet pile and concrete wall structures. Wherestructural and hard components are proposed, they should be used only in smallsegments, be minimized to toe and lower slope applications, consistent with goodengineering practices and include native planting components wherever possible.Generally purely hard or structural approaches that do not include native plantings orother on-site mitigation measures will be difficult to obtain permits for from either Cityor County approval agencies if they are over 15 meters (50 feet) in cumulative creeklength.3.6.6 Retrofitting and Repair or Replacement of Existing Hydraulic Structures andRevetmentsThere are many old, damaged and failing bank revetment structures that line the streams in urbanportions of San Luis Obispo Creek and major tributaries. In many cases these were designed andconstructed by private property owners, installed prior to 1982, and do not meet current1 Biotechnical. An applied science that combines structural, biological and ecological concepts to constructliving structures for erosion, sediment and flood control.SLO Creek Drainage Design Manual 18 February 2003