Chapter 17.47
NATURAL HAZARDS, BEACHES AND DUNES
Sections:
17.47.020 Development in identified hazard areas.
17.47.030 Development in ocean beaches and dune areas.
17.47.010 Purpose.
The purpose of this section is to protect the public safety and welfare through recognition that different geological formations and landforms have different hazard characteristics with respect to suitability for development. These differences are caused by faults, flood potential, landslide potential, high groundwater, stream bank erosion, bluff erosion, beach erosion, ocean flooding, storm waves, and other factors. The intent is to reduce the losses resulting from these hazards. (Ord. 2000-11 § 7; Ord. 84-2 § 3.112(1))
17.47.020 Development in identified hazard areas.
A. Hazards Identified and Applicability of Standards. Specific natural hazard areas have been identified in Environmental Geology of Lincoln County, Oregon, Bulletin 81 (State of Oregon Department of Geology and Mineral Industries, 1973) and Environmental Hazard Inventory (RNKR Associates, 1978), and other sources. They are depicted on the comprehensive plan natural hazards map, as supplemented by Priest, G.R., and Allan, J.C., 2004.1 For purposes of this chapter, in cases of conflict between a cited source and the map, as supplemented by the 2004 Priest and Allan report, the map, as so supplemented, will prevail.
Natural hazard areas identified in Environmental Geology of Lincoln County, Oregon, Bulletin 81 (State of Oregon Department of Geology and Mineral Industries, 1973) and Environmental Hazard Inventory (RNKR Associates, 1978) are advisory only. The city does not require analysis or mitigation for property identified as being in these hazard areas, but recommends that developers seek professional advice.
Development of property identified by Priest, G.R., and Allan, J.C., 2004, as subject to coastal erosion must meet the requirements of this chapter; however, the following activities are exempt:
1. Maintenance, repair, or alterations to existing structures that do not alter the building footprint or foundation;
2. New construction or maintenance, repair, or alterations to existing structures on a portion of the lot that lies outside the coastal erosion zones;
3. Exploratory excavations under the direction of a registered engineering geologist or geotechnical engineer;
4. Construction for which a building permit is not required;
5. Maintenance and reconstruction of public and private roads, streets, parking lots, driveways, and utility lines, provided the work does not extend outside the previously disturbed area;
6. Activities of emergency responders intended to reduce or eliminate an immediate danger to life or property.
B. Required Geotechnical Analysis. Development of all types, except beach front protective structures and natural means of beach protection, in coastal erosion hazard areas identified by Priest, G.R., and Allan, J.C., 2004, may not occur until an engineering geologist, certified to practice in Oregon, or geotechnical engineer registered and licensed to practice in Oregon, completes a review of the project site. To the extent the engineering geologist or geotechnical engineer deems necessary, the review shall incorporate analysis and recommendations of an Oregon-certified coastal engineer and of technical experts from other fields outside of engineering geology. The review shall be prepared at the applicant’s expense. The geologist or geotechnical engineer must submit (electronically) the review to the city as a written report that, if written or last updated more than a year prior to the first building inspection, must be updated to reflect current conditions. In reviewing the submitted geotechnical report, the city may consult with, among others, the Oregon Department of Geology and Mineral Industries, the Department of Land Conservation and Development, and a certified engineering geologist or geotechnical engineer. The city assumes no responsibility for the quality or accuracy of a geotechnical report.
Report Contents. Any geotechnical report must follow professional guidelines established by the Oregon State Board of Geologist Examiners, and include an explanation of the degree the hazard affects the property use in question, an explanation of the measures to be employed to minimize losses associated with the hazard, including, but not necessarily limited to, erosion control, vegetation removal, and slope stabilization, and an explanation of the hazard-associated consequences the development and the loss-minimizing measures will have on the surrounding properties.
For development activities of all types on a property in the coast erosion hazard zones, defined by Priest and Allan, 2004, except for beach front protective structures and natural means of ocean beach protection, the geotechnical report must include, but is not limited to, the following items:
1. Site Description.
a. The history of the site and surrounding areas, such as previous riprap or dune grading permits, erosion events, exposed trees on the beach, or other relevant local knowledge of the site.
b. Topography, including elevations and slopes on the property.
c. Vegetation cover.
d. Subsurface materials – the nature of the rocks and soils.
e. Conditions of the seaward front of the property, particularly for sites having a sea cliff.
f. Presence of drift logs or other flotsam on or within the property.
g. Description of streams or other drainage that might influence erosion or locally reduce the level of the beach.
h. Proximity of nearby headlands that might block the long shore movement of beach sediments, thereby affecting the level of the beach in front of the property.
i. Description of any shore protection structures that may exist on the property or on nearby properties.
j. Presence of pathways or stairs from the property to the beach.
k. Existing human impacts on the site, particularly those that might alter the resistance to wave attack.
2. Description of the Fronting Beach.
a. Average widths of the beach during the summer and winter.
b. Median grain size of beach sediment.
c. Average beach slopes during the summer and winter.
d. Elevations above mean sea level of the beach at the seaward edge of the property during summer and winter.
e. Presence of rip currents and rip embayment that can locally reduce the elevation of the fronting beach.
f. Presence of rock outcrops and sea stacks, both offshore and within the beach zone.
g. Information regarding the depth of beach sand down to bedrock at the seaward edge of the property.
3. Analyses of Erosion and Flooding Potential.
a. Analysis of DOGAMI beach monitoring data available for the site.
b. Analysis of human activities affecting shoreline erosion.
c. Analysis of possible mass wasting, including weathering processes, land sliding or slumping.
d. Calculation of wave runup beyond mean water elevation that might result in erosion of the sea cliff or foredune (see Stockdon, 20062).
e. Evaluation of frequency that erosion-inducing processes could occur, considering the most extreme potential conditions of unusually high water levels together with severe storm wave energy.
f. For dune-backed shoreline, use an appropriate foredune erosion (Komar et al. 19993) or time-dependent erosion model (e.g., Kriebel and Dean, 19934) to assess the potential distance of property erosion, and compare the results with direct evidence obtained during site visit, aerial photo analysis, or analysis of DOGAMI beach monitoring data.
g. For bluff-backed shorelines, use a combination of published reports, such as DOGAMI bluff and dune hazard risk zone studies, aerial photo analysis, and field work, to assess the potential distance of property erosion.
h. Description of potential for sea level rise, estimated for local area by combining local tectonic subsidence or uplift with global rates of predicted sea level rise.
i. An estimation of the annual erosion rate at the site.
4. Assessment of Potential Reactions to Erosion Episodes.
a. Determination of legal restrictions of shoreline protective structures (Goal 18 prohibition, local conditional use requirements, priority for nonstructural erosion control methods).
b. Assessment of potential reactions to erosion events, addressing the need for future erosion control measures, building relocation, or building foundation and utility repairs.
c. An annual erosion rate for the property.
5. Recommendations.
a. Based on results from the above analyses, recommended setbacks, building techniques, or other mitigation to ensure an acceptable level of safety and compliance with all local requirements.
b. A plan for preservation of vegetation and existing grade within the setback area, if appropriate.
c. Consideration of a local variance process to reduce the building setback on the side of the property opposite the ocean, if this reduction helps to lessen the risk of erosion, bluff failure or other hazard.
d. Methods to control and direct water drainage away from the ocean (e.g., to an approved storm water system), or, if not possible, to direct water in such a way so as to not cause erosion or visual impacts.
C. Compliance. Permitted development shall comply with the recommendations in any required geotechnical report and any report required by the building code.
At the time of footing inspection, or, if no footing inspection is required, at the time of the first building inspection, the author of the geotechnical report must certify that the development was constructed in accordance with the report’s recommendations.
D. Bluff Setback. No bluff setback is required for public infrastructure, beach front protective structures, or natural means of beach protection. The footprint of any other new structure or any horizontal addition requiring at least one footing in ocean bluff areas must be set back from the bluff a distance of at least 60 times the average annual erosion rate (determined by the geotechnical analysis) plus five feet. The bluff, for this purpose, shall be determined by the city through inspection of aerial photos, the most recent LIDAR data, and the dividing line between the active and the high-risk erosion zones identified in the 2004 Priest maps referenced above. If the city cannot determine the location of a bluff, the geotechnical analysis, provided at the applicant’s expense, shall determine an appropriate site for the structure, if one exists. The bluff setback must be measured from the unaltered bluff edge, as based upon a recent (conducted within the 12 months prior to the date of the geotechnical analysis) topographic survey performed by a land surveyor licensed in the state of Oregon. If damaged, an existing structure that does not conform to the setback may be rebuilt in conformance with Chapter 17.64 LCMC, Nonconforming Situations. Reconstruction shall comply with recommendations provided in a report from an engineering geologist licensed in the state of Oregon or a registered geotechnical engineer licensed in the state of Oregon, or both, as determined necessary by the building official.
E. Other Policies That Apply. If structures to protect shorelands, beaches and dunes, or flood areas are proposed, comprehensive plan “Shorelands, Beaches, Dunes, Estuaries, and Ocean Resources” Policies 7, 8, 9, 21 and 22 also apply. (Ord. 2022-11 § 1; Ord. 2020-04 § 1; Ord. 2012-09 § 1; Ord. 2011-16 § 1; Ord. 2004-05 § 4; Ord. 2000-11 § 7; Ord. 84-2 § 3.112(2))
17.47.030 Development in ocean beaches and dune areas.
This section ensures compliance with Statewide Goal 18.
A. Use Permitted/Prohibited. Residential development and commercial and industrial buildings are prohibited on active foredunes, conditionally stable foredunes that are subject to ocean undercutting or wave overtopping, and deflation plains that are subject to ocean flooding.
Other development that does not disturb the dune and dune vegetation significantly (e.g., fences that do not affect sand erosion or migration, a boardwalk) may be permitted in these areas, only if:
1. A geotechnical review, as described in LCMC 17.47.020(B), is completed for development activities of all types, except beach front protective structures and natural means of ocean beach protection. The written geotechnical report for this purpose must include the following information, in addition to other stated requirements:
a. The type of proposed use and the adverse effects it might have on the site and the surrounding area. As used in this subsection, “adverse effects” are those that create a hazard to life, public or private property, or the natural environment;
b. The measures to be employed to protect the site and the surrounding area from adverse effects created by the use; and
c. An explanation of the hazard-associated consequences the development and the loss-minimizing measures will have on the surrounding properties;
2. The geotechnical review concludes that the development as approved, with any conditions and measures to be employed to minimize losses associated with ocean undercutting, wave overtopping, and ocean flooding, is not likely to be subject to significant losses associated with these hazards during the design life of the development, or is of nominal value; and
3. The geotechnical review concludes that the development as approved, with any conditions and measures to be employed to minimize losses associated with ocean undercutting, wave overtopping, and ocean flooding, will not have significant adverse consequences associated with these hazards on surrounding properties.
B. Limit on Permitted Development. Development, except for beach front protective structures and natural means of ocean beach protection, in ocean beach and dune areas will be permitted only if the development predictably can be designed so that there will be no significant adverse impacts on the site and on adjacent properties from geologic hazards, wind erosion, and water erosion caused by ocean flooding, storm waves, or other causes, and is consistent with the requirements of Shoreland Policy 8.
C. Grading and Breaching of Foredunes. Grading and breaching of foredunes is prohibited.
D. Protective Structures. The city will rely on the State of Oregon Parks and Recreation Department (OPRD) to control the development of beach front protective structures and natural means of protection; however, the state will not issue a permit until the city has had an opportunity to determine that such protection complies with the applicable provisions of this chapter, including this subsection. Protective structures must be kept in good repair and are subject to additional compliance standards as well as enforcement under Chapter 8.10 LCMC.
E. Protection Project Permits. Shoreland (other than ocean beach front) protection projects, such as groins, bulkheads and sea walls, may not begin until a permit is obtained from the city. No approval to the state or city permit for a shoreland protection project will be issued until the developer has supplied to the city a plan, prepared by a certified engineering geologist or by a registered professional engineer qualified to practice geotechnical engineering, which indicates the nature and scope of the proposed protective activity. Nonstructural means of protection that will be effective to control erosion must be the first order of consideration in protecting shorelands. The use of structures, such as groins, bulkheads or sea walls, will not be allowed unless nonstructural means cannot protect the property and the adverse consequences created by such structures, both erosion-related and aesthetic, will be insignificant.
F. Vegetation. If vegetation is to be removed because of the development of any protection structure, a revegetation plan must be submitted. The plan must illustrate how vegetation removal will be minimized to prevent dune form alteration and exposure to erosion. The plan must provide for revegetation as extensive as or greater than exists prior to disruption. The protection structure will be approved by the state or permitted by the city only if the vegetation removal and the revegetation will be conducted so as to prevent dune form alteration and exposure to erosion resulting from the removal and revegetation.
G. Groundwater. No development in ocean beach and dune areas may use existing groundwater sources as a primary domestic water source. Developments may use existing groundwater sources for limited irrigation purposes, after securing all necessary state permits, and the submission to and approval by the city of written findings, prepared by a certified engineering geologist or by a registered professional engineer qualified to practice geotechnical engineering, that the irrigation will not cause groundwater drawdown to levels which would lead to loss of stabilizing vegetation or intrusion of salt water into the groundwater supply. (Ord. 2012-09 § 1; Ord. 2011-16 § 1; Ord. 2004-05 § 4; Ord. 2000-11 § 7; Ord. 84-2 § 3.112(3))
Priest, G.R., and Allan, J.C., 2004, Evaluation of coastal erosion hazard zones along dune and bluff backed shorelines in Lincoln County, Oregon: Cascade Head to Seal Rock, Technical Report to Lincoln County (Oregon Department of Geology and Mineral Industries, Open-File Report O-04-09).
Stockdon, H.F., Holman, R.A., Howd, P.A., and Sallenger, A.H., 2006, Empirical parameterization of setup, swash, and runup: Coastal Engineering, v. 53, no. 7, p. 573-588.
Komar, P.D., McDougal, W.G., Marra, J.J., and Ruggiero, P., 1999, The rational analysis of setback distances: Applications to the Oregon Coast: Shore & Beach, v. 67, p. 41-49.
Kriebel, D.L., and Dean, R.G., 1993, Convolution method for time-dependent beach-profile response: Journal of Waterway, Port, Coastal and Ocean Engineering, v. 119, no. 2, p. 206-226.