29.15.080 Flood hazard reduction.
(1) Development in floodplains shall avoid significantly or cumulatively increasing flood hazards. Development shall be consistent with this SMP, as well as applicable guidelines of FEMA and PMC 29.25.060, Flood Hazard Areas, and Chapter 24.20 PMC, Provisions for Flood Hazard Protection.
(2) Existing structural flood hazard reduction measures, such as levees, may be repaired and maintained as necessary to protect legal uses on the landward side of such structures. Increases in height of an existing levee, with any associated increase in width, that may be needed to prevent a reduction in the authorized level of protection of existing legal structures and uses, shall be considered an element of repair and maintenance.
(3) Flood hazard reduction measures shall not result in channelization of normal stream flows, interfere with natural hydraulic processes, such as channel migration, or undermine existing structures or downstream banks.
(4) New Development and Subdivisions. Approve new development or subdivisions when it can be reasonably foreseeable that the development or use would not require structural flood hazard reduction measures within the floodway during the life of the development or use consistent with the following (WAC 173-26-221(3)(c)(i)):
(a) Floodway. New development and subdivisions shall be subject to applicable floodway regulations in PMC 29.25.060, Flood hazard areas, and Chapter 24.20 PMC, Provisions for Flood Hazard Protection.
(5) New public and private structural flood hazard reduction measures shall be approved when a scientific and engineering analysis demonstrates the following:
(a) They are necessary to protect existing development;
(b) Nonstructural measures, such as setbacks, land use controls, wetland restoration, dike removal, use or structure removal or relocation, biotechnical measures, and storm water management programs are not feasible;
(c) Adverse impacts on ecological functions and priority species and habitats can be successfully mitigated so as to ensure no net loss; and
(d) Appropriate vegetation conservation actions are undertaken consistent with PMC 29.15.050, Shoreline vegetation conservation.
(6) Flood hazard reduction measures shall be placed landward of associated wetlands and designated shoreline buffers, except for actions that increase ecological functions, such as wetland restoration, or when no other alternative location to reduce flood hazard to existing development is feasible as determined by the Shoreline Administrator.
(7) New public structural flood hazard reduction measures, such as levees, shall dedicate and improve public access pathways, unless public access improvements would cause unavoidable health or safety hazards to the public, inherent and unavoidable security problems, unacceptable and unmitigable significant adverse ecological impacts, unavoidable conflict with the proposed use, or a cost that is disproportionate and unreasonable to the total long-term cost of the development.
(8) In those instances when management of vegetation as required by this SMP conflicts with vegetation provisions included in state, federal, or other flood hazard agency documents governing City-authorized, legal flood hazard reduction measures, the vegetation requirements of this SMP will not apply. However, the applicant shall submit documentation of these conflicting provisions with any shoreline permit applications and shall comply with all other provisions of this section and this SMP that are not strictly prohibited by the approving flood hazard agency.
(9) The removal of gravel or other riverbed material for flood-management purposes shall be consistent with the PMC 29.20.050, Dredging and dredge material disposal, and PMC 29.20.090, Mining, and be allowed only after a biological and physical conditions study shows extraction has no effect on or provides a long-term benefit to flood hazard reduction, and does not result in a net loss of ecological functions.
(10) Roads shall be located outside the floodway, except necessary crossings, which shall be placed perpendicular to the water body as much as is physically feasible. New transportation facilities shall be designed so the effective base flood storage volume of the floodplain is not reduced. The applicant shall provide all necessary studies, reports, and engineering analyses, which shall be subject to review and modification by the Shoreline Administrator. If proposed transportation facilities effectively provide flood control, they shall comply with policies and regulations of this section. [Ord. 4314 § 2, 2016; Code 1970 § 29.01.270.]