18E.110.040 Erosion Hazard Area Standards.
A. Active Shoreline Erosion Hazard Areas. Any development, encroachment, filling, clearing, or grading, timber harvest, building structures, impervious surfaces, and vegetation removal shall be prohibited within active shoreline erosion hazard areas and associated buffers except as specified in the following standards:
1. Shoreline Stabilization. See PCC 18S.30.070 for additional shoreline stabilization policies and regulations.
2. Shoreline Stabilization Standards. Shoreline stabilization is subject to the following:
a. The proposed shoreline protection measure shall comply with the standards set forth in PCC 18E.40.040.
b. A geological assessment-shoreline erosion geotechnical report shall be conducted in accordance with the provisions set forth in PCC 18E.110.030 B. that indicates that the shoreline is currently experiencing active erosion (i.e., land retreat or regression).
c. A geological assessment-landslide hazard area letter, evaluation, or report shall be required if the shoreline protection measures(s) will be located within a potential landslide hazard area set forth in Chapter 18E.80 PCC.
d. The use of the shoreline erosion protection measure shall not cause a significant adverse impact on adjacent properties (i.e., increase erosion on adjacent properties).
e. If relocation of development is not feasible, the use of soft armoring techniques is the preferred method for shoreline protection.
f. Hard armoring shoreline erosion control measures may be allowed only when a geological assessment-shoreline erosion geotechnical report, as set forth in PCC 18E.110.030 B., has been completed and indicates the following:
(1) The use of beach nourishment alone or in combination with soft armoring techniques is not adequate to protect the property from shoreline erosion processes;
(2) The property contains an existing structure(s) that will be threatened within the next 10 years; and
(3) Hard armoring shoreline protection measures shall not be allowed for protection of proposed structures when it is determined that the proposed structures can be located landward of the 120-year regression area.
3. Stormwater Conveyance. Surface drainage into an active shoreline erosion hazard area should be avoided. If there are no other alternatives for discharge, then drainage must be collected upland of the top of the active shoreline erosion hazard area and directed downhill in a high density polyethylene stormwater pipe with fuse welded joints that includes an energy dissipating device at the base of the active shoreline erosion area. The pipe shall be located on the surface of the ground and be properly anchored so that it will continue to function under shoreline erosion conditions. The number of these pipes should be minimized along the slope frontage.
4. Utility Lines. Utility lines will be permitted when no other conveyance alternative is available. The line shall be located above ground and properly anchored and/or designed so that it will continue to function under shoreline erosion conditions.
5. Roads, Bridges, and Trails. Roads, bridges, and trails shall be allowed when all of the following conditions have been met:
a. Mitigation measures are provided that ensure the roadway prism and/or bridge structure will not be susceptible to damage from active erosion.
b. The road is not a sole access for a development.
6. Flood Hazard Reduction. Shoreline stabilization activities that are part of flood hazard reduction measures that are identified in the Applicability statement for Flood Hazard Management in PCC 18S.40.060, and that are also included in an applicable comprehensive flood control management plan recognized by Pierce County, shall not be subject to review under this Section but shall be reviewed under the Flood Hazard Management Section of Title 18S PCC.
B. Shoreline Erosion Hazard Management Area. All regulated activities such as but not limited to building structures, impervious surfaces, vegetation removal, timber harvest, and clearing or grading activities may be allowed in areas located within 200 feet of an active shoreline erosion hazard area subject to the following standards:
1. The Department reviews and approves a geological assessment-shoreline erosion hazard geotechnical report and concurs that the proposed project area is located outside an active shoreline hazard area and the required buffer, as set forth in PCC 18E.110.050.
2. The proposed recommendations and mitigation measures contained within the geotechnical report are adequate to reduce or mitigate risks to the natural environment, health, and safety.
3. Surface drainage from the proposed project area, including downspouts, landscape irrigation systems, and runoff from paved or unpaved surfaces upland of the shoreline, shall not be directed through an active shoreline erosion hazard area or its associated buffer unless it is conveyed in conformance with the provisions in subsection A.2. above.
4. Stormwater retention and detention systems, such as dry wells and infiltration systems utilizing buried pipe or french drains, shall not be permitted unless such systems are designed by a professional engineer and the geotechnical report indicates that such a system will not affect the stability of the shoreline.
5. Proposed developments, with the exception of shoreline erosion protection measures, shall be sited far enough from regressing shorelines to provide 120 years of useful life for any proposed structures or infrastructure.
C. Riverine Erosion Hazard Area (Channel Migration Zones) Review. Riverine erosion hazard areas shall be reviewed pursuant to the requirements set forth in Chapter 18E.70 PCC, Flood Hazard Areas.
D. Soil Erosion Hazard Area Review. Soil erosion hazard areas shall be reviewed pursuant to the requirements set forth in Title 17A PCC, Construction and Infrastructure Regulations – Site Development and Stormwater Drainage.