35.20.290 Additional regulations – Existing structural shoreline armoring

35.20.290 Additional regulations – Existing structural shoreline armoring.

(1) Existing structural shoreline armoring may be replaced with a similar structure, pursuant to a statement of exemption, if there is a demonstrated need to protect primary uses or structures including residences, public transportation infrastructure, or essential public facilities from erosion caused by currents, tidal action, or waves and all of the following apply:

(a) The existing structure no longer adequately serves its purpose and the replacement structure performs the same stabilization function of the existing structure and does not require additions to or increases in size. Additions to or increases in size of existing shoreline stabilization measures shall be considered new structures.

(b) The replacement structure shall not encroach waterward of the ordinary high water mark or the 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 shoreline stabilization structure.

(d) Nonstructural measures, such as planting vegetation, or installing on-site drainage improvements, are not feasible or not sufficient.

(e) Alternative or soft stabilization approaches shall be considered prior to in-kind replacement.

(f) The replacement structure is designed, located, sized, and constructed to minimize effects on shoreline processes and fish and wildlife habitat, and will not result in a net loss of shoreline functions.

(g) Where possible or as an element of mitigation sequencing, failing, harmful, unnecessary, or ineffective structures should be removed, and shoreline ecological functions and processes should be restored using nonstructural or soft stabilization measures.

(h) The need for a replacement structure and consistency with the above standards and other applicable provisions of this article is demonstrated through a geotechnical report.

(2) Removal of older structures shall be required as replacement structures are put in place if leaving the existing structure in place would cause a net loss of ecological functions. Exceptions may be made by the County in cases where removal would cause more ecological disturbance to critical saltwater or critical freshwater habitats than leaving the remnant structure in place.

(3) Bank stabilization may be permitted on Type S, F, Np, Ns waters for the purpose of retarding erosion and protecting legally placed, existing residential structures or essential public facilities/infrastructure which cannot be moved, subject to all of the following criteria:

(a) The bank stabilization shall be designed by a civil engineer licensed in the State of Washington with sufficient expertise in hydraulics, hydrology, and/or geomorphology, along with a biologist to assess habitat impacts; and

(b) The civil engineer shall consider and implement bioengineered stabilization measures unless hydraulic analysis indicates that hard structural stabilization is necessary due to the site conditions; and

(c) Avoidance or relocation of the structure or improvement that needs protection has been reviewed and is not feasible or practical; and

(d) Stabilization activities shall minimize any potential negative impacts to the natural functions and processes of the stream; and

(e) The effects of the stabilization to upstream and downstream properties are clearly disclosed and taken into consideration during the design of the structure; and

(f) The materials used in or near surface waters shall not contain petroleum-based treatments or preservatives, including creosote, copper and arsenic.