Drainage Design Manual - the City of San Luis Obispo

construction, unless otherwise allowed by the City Engineer in consultation with theCity Community Development Director.• Commercial buildings located in the City’s central business district can be built atpresent grade within the FEMA 100-year floodplain, provided the building is “floodproofed”according to current FEMA guidelines and criteria, as approved by the CityEngineer.• The floodplain may not be modified in ways that increase water velocities such thatstream bank erosion will be increased, unless the stream banks are protected to preventthe increased erosion.• Existing nonconforming structures are allowed to remain in the in-fill floodplainmanagement area. Existing nonconforming structures may be modified only when thestructure is small relative to the structure and with approval of the City Engineer orCounty Public Works Director.• Flood proofing following FEMA standards and guidelines is encouraged for existingbuildings within the flood-prone in-fill areas.• The setback from the top of bank shall be consistent with the City’s existing policies forcreek setback and shall be maintained as a flood passage way. No new buildings,structures, or fences that could potentially block the downstream passage offloodwaters will be permitted in this area.3.5.2 Mid-Higuera Specific Plan Area• For the floodplain area within the area defined by the City as the Mid-Higuera SpecificPlan area, (generally extending along San Luis Obispo Creek between the Marsh StreetBridge at Highway 101 downstream to below the Madonna Road Overcrossing,(Figure 3-2), no building replacement, or building additions to the first floor will bepermitted in a 7.5 m (25 ft) zone, as measured from top of bank. This requirement maybe waived at the discretion of the Community Development Director and City Engineerfor minor additions and remodeling of existing single-family housing.Replacement of existing buildings and structures with new buildings and structures thatoccupy the exact footprint (or less) of a pre-existing building will be permitted on allcreek reaches of San Luis Obispo, and Stenner Creeks upstream of the Mid HigueraSpecific Plan area, consistent with the City’s existing creek setback policies.• For 100-year floodplain areas extending more than 7.5 m (25 ft) from top of bank,(Figure 3-2) construction of new fences shall be made of permeable materials such aschain -link, wrought iron, etc. that allow relatively free passage of floodwater. Projectdesigns shall include provision of return flow paths for overbank floodwater to SanLuis Obispo Creek. Chain link fencing shall not be used where flowing water is likelyto deposit debris against the fence, because the flow is perpendicular to the fence, ornearly so.SLO Creek Drainage Design Manual 13 February 2003