(A) Purpose. The purpose of this overlay zone is to avoid development hazards in the areas of the city and the urban growth boundary, which have been mapped as inundation zones (limit construction of new essential facilities and special occupancy structures as defined in O.R.S. 455.447 in tsunami inundation zones). The following special regulations apply to all properties, which lie wholly or partially within one or more of these areas (refer to tsunami hazard map of the city quadrangle).
(B) Scope.
(1) Protect life and property from natural disasters and hazards.
(2) Provide appropriate safeguards to protect development from natural hazards.
(C) Authorization. In addition to complying with the provisions of the underlying zoning district, uses and activities shall comply with the provisions of this overlay zone, as required by O.R.S. 455.447.
(D) Hazard Overlay Zone boundaries. The boundaries of the HO District Zone shall be the same as the boundaries of the Cascadia Subduction Zone Tsunami Inundation Zone map for the city. These areas shall be part of the zoning ordinance. The underlying zoning district regulations shall remain in effect and all development shall be subject to the requirements of both the underlying zone district and the Hazards Overlay Zone.
(E) Site investigation required.
(1) A site investigation shall be required by the city for subdivision, partitioning, conditional use or other site development approved by the City Planning Commission in the Hazards Overlay Zone. The city planning official shall require the site investigation in all land use applications handled administratively in which City Planning Commission approval is not required. Site investigation reports shall be performed by an especially qualified engineer or engineering geologist registered by the state to practice as such, in areas requiring specialized knowledge, such as Tsunami Inundation Zones, the city may require that a person with experience or training in such areas be employed.
(2) Essential facilities and new special occupancy structures shall not be constructed in Tsunami Inundation Zones established by Department of Geology and Minerals Industries (DOGAMI), unless specifically exempted by O.R.S. 455.446 or given an exception by the DOGAMI governing board.
(3) New “essential facilities”, special occupancy structures and all new hazardous facilities and major structures defined in O.R.S. 455.447 that are constructed in a Tsunami Inundation Zone are mandated to seek advice from DOGAMI.
(F) Method for minimizing Inundation Zone hazards.
(1) The owner or developer will have a new site investigation report made for the site prepared to determine the nature and extent of inundation area on the site, unless the Planning Commission determines that an adequate site investigation report has already been undertaken.
(2) The method used to conduct the site investigation report must be acceptable to a qualified engineering geologist and acknowledged by DOGAMI.
(a) The report shall be based on historical inundation information.
(b) In situations where similar source, tectonic and coastal environments exist and modeled inundation has been done elsewhere, interpolate inundation based on maximum modeled inundation in nearby/bounding areas.
1. If available, use low resolution, regional simulations to estimate the relative amplification of tsunamis by offshore bathymetric effects.
2. Interpolation should take into account the behavior of tsunamis of similar size for terrain analogous to that of the target area.
(c) The report should extrapolate lower-resolution model data on land to estimate inundation and add a safety factor for both inundation and elevation. Extrapolation should take into account the behavior of tsunamis of similar size for terrain analogous to that of the target area, even for tsunamis from other parts of the world.
(d) In the absence of other tsunami hazard information, consultation with your NTHMP scientific representative, for tsunami evacuation planning.
(3) If the detailed site investigation report indicates that significant amounts of inundation area are in locations required for development, the developer or owner shall have a report prepared by a qualified engineering geologist, which indicates suitable techniques to minimize potential hazards to facilities on the parcel, adjacent and nearby property.
(4) Buildings identified for vertical evacuation should have the following characteristics:
(a) Designed and built using modern structural engineering;
(b) Constructed of reinforced concrete or steel; and
(c) Well maintained with buildings materials in good condition.
(G) Conditional uses. The following conditional uses may be permitted subject to a conditional use permit: transportation facilities and improvements:
(1) Transportation projects that are not designated improvements in the Transportation System Plan; and
(2) Transportation projects that are not designated and constructed as part of an approved subdivision or partition.
(Ord. 1285, passed 3-3-2014; Ord. 1320, passed 3-20-2017) Penalty, see § 152.999