16.06.190 Shore stabilization.
The following provisions shall apply to shore stabilization projects:
(1) Shore stabilization projects shall be allowed only where there is evidence of erosion which clearly represents a threat to existing property, structures, or facilities, and which stabilization will not jeopardize other upstream or downstream properties.
(2) Stabilization projects shall be developed under the supervision of, or in consultation with, agencies or professionals with appropriate expertise.
(3) Stabilization projects shall be confined to the minimum protective measures necessary to protect the threatened property.
(4) The use of fill to restore lost land may accompany stabilization work, provided the resultant shore does not extend beyond the new ordinary high water mark, finished grades are consistent with abutting properties, a restoration plan is approved for the area, and the fill material is in compliance with Section 16.06.210 (Filling).
(5) Stabilization projects shall use design, material, and construction alternatives that do not require high or continuous maintenance and which prevent or minimize the need for subsequent stabilization to other segments of the shore. Junk car bodies and other unsuitable debris are not to be used in shore stabilization projects.
(6) Stream bank and lakeshore protection shall be accomplished using bioengineered (biotechnical) designs employing living plant materials as primary structural components of resistance to erosion and mass wasting, unless a report prepared by a qualified engineer experienced in soil bioengineering (biotechnical) and shoreline protection demonstrates that conventional structural armoring is the only feasible means of stabilizing the subject stream bank or lakeshore.
(7) Applications to construct or enlarge dikes or levees shall meet the requirements of Chapter 11.19.
(8) Revetments and bulkheads shall be no higher than necessary to protect and stabilize the shore.
(9) Breakwaters shall be constructed of floating or open-pile designs rather than fill, riprap, or other solid construction methods.
(10) All new flood control projects shall define maintenance responsibilities and a funding source for operations, maintenance, and repairs for the life of the project.
(11) Additional Shoreline Standards for Shore Stabilization. The requirements below shall apply to all shore stabilization activities within shoreline jurisdiction.
(A) Where feasible, dikes and levees shall be located outside of the floodway or channel migration zone of the river or stream in order to minimize any attendant increase in water stage and stream flow velocity over existing conditions.
(B) Riprapping and other shore stabilization measures shall be designed, located, and constructed in such a manner as to minimize the disruption of natural channel characteristics.
(C) Where a geotechnical analysis or report is required, it shall meet the provisions of Section 16.03.180(6) (flood hazard reduction and shore modification in shoreline jurisdiction).
(D) When structural flood hazard reduction and shore stabilization measures are necessary, they shall be located and designed to meet the provisions of Section 16.03.180(6) (flood hazard reduction and shore modification in shoreline jurisdiction).
(E) Demonstration of Necessity. New structural shore stabilization measures shall not be allowed except when necessity is demonstrated in the following manner:
(i) New or enlarged structural stabilization measures for an existing primary structure, including residences, shall not be allowed unless there is conclusive evidence, documented by a geotechnical analysis, that the structure is in danger from shoreline erosion caused by currents or waves. Normal sloughing, erosion of steep bluffs, or shoreline erosion itself, without a scientific or geotechnical analysis, is not demonstration of need. The geotechnical analysis should evaluate on-site drainage issues and address drainage problems away from the shoreline edge before considering structural shore stabilization.
(ii) Erosion control structures in support of new nonwater-dependent development, including single-family residences, when all of the conditions below apply:
a. The erosion is not being caused by upland conditions, such as the loss of vegetation and drainage.
b. Nonstructural measures, such as placing the development further from the shoreline, planting vegetation, or installing on-site drainage improvements, are not feasible or not sufficient.
c. The need to protect primary structures from damage due to erosion is demonstrated through a geotechnical report. The damage must be caused by natural processes, such as tidal action, currents, and waves.
(iii) Erosion control structures in support of water-dependent development when all of the conditions below apply:
a. The erosion is not being caused by upland conditions, such as the loss of vegetation and drainage.
b. Nonstructural measures, planting vegetation, or installing on-site drainage improvements are not feasible or not sufficient.
c. The need to protect primary structures from damage due to erosion is demonstrated through a geotechnical report.
(F) Erosion control structures to protect projects for the restoration of ecological functions or hazardous substance remediation projects pursuant to the Model Toxics Control Act (Chapter 70.105D RCW) shall not be allowed unless there is conclusive evidence, documented by a geotechnical analysis, that demonstrates that nonstructural measures such as planting vegetation, or installing on-site drainage improvements, are not feasible or not sufficient.
(G) An existing shore stabilization structure may be replaced with a similar structure if there is a demonstrated need to protect principal uses or structures from erosion. For purposes of this section, standards on shore stabilization measures, "replacement" means the construction of a new structure to perform a shore stabilization function of an existing structure which can no longer adequately serve its purpose. Additions to or increases in size of existing shore stabilization measures shall be considered new structures under subsection (11)(E) of this section.
(i) Replacement walls or bulkheads shall not encroach waterward of the ordinary high water mark or existing structure unless the residence was occupied prior to January 1, 1992, and there are overriding safety or environmental concerns. In such cases, the replacement structure shall abut the existing shore stabilization structure.
(ii) Soft shore stabilization measures that provide restoration of shoreline ecological functions may be permitted waterward of the ordinary high water mark. (Ord. 2123, § 1 (Att.), 2021.)