29.20.050 Dredging and dredge material disposal

29.20.050 Dredging and dredge material disposal.

(a) New dredging shall be permitted only where it is demonstrated that the proposed water-dependent or water-related uses will not result in significant or ongoing adverse impacts to water quality, fish and wildlife habitat conservation areas and other critical areas, flood holding capacity, natural drainage and water circulation patterns, significant plant communities, prime agricultural land, and public access to shorelines, unless one or more of these impacts cannot be avoided. When such impacts are unavoidable, they shall be minimized and mitigated such that they result in no net loss of shoreline ecological functions.

(b) Dredging and dredge disposal shall be prohibited on or in archaeological sites that are listed on the National Register of Historic Places and the Washington Heritage Register until such time that they have been reviewed and approved by the appropriate agency.

(c) Dredging techniques that cause minimum dispersal and broadcast of bottom material shall be used, and only the amount of dredging necessary shall be permitted.

(d) Dredging shall be permitted only:

(i) For navigation or navigational access;

(ii) In conjunction with a water-dependent use of water bodies or adjacent shoreline areas;

(iii) As part of an approved habitat improvement project;

(iv) To improve water flow or water quality; provided, that all dredged material shall be contained and managed so as to prevent it from re-entering the water; or

(v) In conjunction with a bridge, navigational structure, or wastewater treatment facility for which there is a documented public need and where other feasible sites or routes do not exist.

(e) Dredging for fill is prohibited except where the material is necessary for restoration of shoreline ecological functions.

(a) Upland dredge material disposal within shoreline jurisdiction is discouraged. In the limited circumstances when it is allowed, it will be permitted under the following conditions:

(i) Shoreline ecological functions and processes will be preserved, restored, or enhanced, including protection of surface and groundwater;

(ii) Erosion, sedimentation, floodwaters, or runoff will not increase adverse impacts on shoreline ecological functions and processes or property; and

(iii) The site will ultimately be suitable for a use allowed by this SMP.

(b) Dredge material disposal shall not occur in wetlands, except as authorized by special use permit as part of a shoreline restoration project.

(c) Dredge material disposal within areas assigned an aquatic environment designation may be approved only when authorized by applicable agencies, which may include the USACE pursuant to Section 404 (Clean Water Act) permits, WDFW’s hydraulic project approval, and/or the dredged material management program of the WDNR; and when one of the following conditions apply:

(i) Land disposal is infeasible, less consistent with this SMP, or prohibited by law; or

(ii) Disposal as part of a program to restore or enhance shoreline ecological functions and processes is not feasible.

(d) Dredge materials approved for disposal within areas assigned an Aquatic environment designation shall comply with the following conditions:

(i) Aquatic habitat will be protected, restored, or enhanced;

(ii) Adverse effects on water quality or biologic resources from contaminated materials will be mitigated;

(iii) Shifting and dispersal of dredge material will be minimal; and

(iv) Water quality will not be adversely affected.

(e) When required by the Shoreline Administrator, revegetation of land disposal sites shall occur as soon as feasible in order to retard wind and water erosion and to restore the wildlife habitat value of the site. Native species shall be used in the revegetation.

(f) Dredge material disposal operating periods and hours shall be limited to those stipulated by the WDFW and hours from 7:00 a.m. to 5:00 p.m. Monday through Friday, except in time of emergency as authorized by the Shoreline Administrator. Provisions for buffers at land disposal or transfer sites, in order to protect public safety and other lawful interests and to avoid adverse impacts, shall be required.

(3) Submittal Requirements. The following information shall be required for all dredging applications:

(a) A description of the purpose of the proposed dredging and analysis of compliance with the policies and regulations of this SMP.

(b) A detailed description of the existing physical character, shoreline geomorphology, and biological resources provided by the area proposed to be dredged, including:

(i) A site plan map outlining the perimeter of the proposed dredge area, including the existing bathymetry (water depths that indicate the topography of areas below the OHWM), and having data points at a minimum of two-foot depth increments.

(ii) A critical areas detailed study according to PMC 29.25.020(10).

(iii) A mitigation plan, if necessary, to address any identified adverse impacts on ecological functions or processes.

(iv) Information on stability of areas adjacent to proposed dredging and spoils disposal areas.

(v) A detailed description of the physical, chemical, and biological characteristics of the dredge materials to be removed, including:

(A) Physical analysis of material to be dredged (e.g., material composition and amount, grain size, organic materials present, and source of material).

(B) Chemical analysis of material to be dredged (e.g., volatile solids, chemical oxygen demand, grease and oil content, and mercury, lead, and zinc content).

(d) Dredging procedure, including the length of time it will take to complete dredging, method of dredging, and amount of materials removed.

(e) Frequency and quantity of project maintenance dredging.

(f) Detailed plans for dredge spoil disposal, including specific land disposal sites and relevant information on the disposal site, including, but not limited to:

(i) Dredge material disposal area;

(ii) Physical characteristics, including location, topography, existing drainage patterns, and surface and groundwater;

(iii) Size and capacity of disposal site;

(iv) Means of transportation to the disposal site;

(v) Proposed dewatering and stabilization of dredged material;

(vi) Methods of controlling erosion and sedimentation; and

(vii) Future use of the site and conformance with land use policies and regulations.

(g) Total estimated initial dredge volume.

(h) Plan for disposal of maintenance spoils for at least a 20-year period, if applicable.

(i) Hydraulic modeling studies sufficient to identify existing geohydraulic patterns and probable effects of dredging. [Ord. 4314 § 2, 2016; Code 1970 § 29.01.350.]