Chapter 18E.110
EROSION HAZARD AREAS

Sections:

18E.110.010    Purpose.

18E.110.020    Erosion Hazard Areas.

18E.110.030    Erosion Hazard Area Review Procedures.

18E.110.040    Erosion Hazard Area Standards.

18E.110.050    Buffer Requirements.

18E.110.060    Appendices.

A.    Geological Assessment – Shoreline Erosion Hazard Geotechnical Letter

B.    Geological Assessment – Shoreline Erosion Hazard Geotechnical Evaluation

C.    Geological Assessment – Shoreline Erosion Hazard Geotechnical Report

18E.110.010 Purpose.

The following statements describe the purpose of this Chapter:

A.    Protect human life and health;

B.    Regulate uses of land in order to avoid damage to structures and property being developed and damage to neighboring land and structures;

C.    Identify and map erosion hazard areas;

D.    Minimize impacts on wetlands and critical fish and wildlife species and their associated habitat that can result from erosion;

E.    Establish a permit requirement and review procedures for development proposals in areas with potential erosion hazards;

F.    Strike a balance between the need to maintain natural shoreline erosion/regression processes and the need to protect existing and proposed development.

(Ord. 2004-56s § 4 (part), 2004)

18E.110.020 Erosion Hazard Areas.

A.    Shoreline Erosion Hazard Indicators. Shoreline erosion hazard areas are areas potentially subject to land regression or retreat due to a combination of geologic, seismic, tidally influenced, and/or hydrologic or manmade factors. Shoreline erosion hazard areas can be identified by the presence of any of the following indicators:

1.    Areas with active bluff retreat that exhibit continuing sloughing or calving of bluff sediments, resulting in a vertical or steep bluff face with little or no vegetation.

2.    Areas with active land retreat as a result of wave action.

B.    Erosion Hazard Area Categories.

1.    Potential Erosion Hazard Areas. Potential erosion hazard areas, as depicted on the Critical Areas Atlas-Erosion Hazard Areas Map, are those areas where the suspected risk of erosion through either loss of soil, slope instability, or land regression is sufficient to require additional review to assess the potential for active erosion activity or apply additional standards. These potential erosion hazard areas are determined using the following criteria:

a.    Shoreline Erosion Hazard Areas. Areas within 200 feet of a freshwater (lake or pond) or marine (Puget Sound, tidal marshes, and estuaries) shoreline, as measured landward perpendicularly from the edge of the ordinary high water mark. (See Figure 18E.110-1 in Chapter 18E.120 PCC.)

b.    Riverine Erosion Hazard Areas. The rivers subject to regulation as a channel migration zone listed in Chapter 18E.70 PCC, Flood Hazard Areas, PCC 18E.70.020 B.4.

c.    Soil Erosion Hazard Areas. Areas identified as having slopes of 20 percent or greater and that are classified as having severe, or very severe erosion potential by the Soil Conservation Service, United States Department of Agriculture (USDA).

2.    Active Shoreline Erosion Hazard Areas. Land areas located directly adjacent to freshwater or marine waters that, through the geological assessment process, are identified as regressing, retreating, or potentially unstable as a result of undercutting by wave action or bluff erosion. The limits of the active shoreline erosion hazard area shall extend landward to include that land area that is calculated, based on the rate of regression, to be subject to erosion processes within the next ten year time period.

3.    Stable Shoreline Erosion Hazard Areas. Areas that have been identified as potential erosion hazard areas, but, through the geological assessment process, meet one of the following conditions:

a.    No indicators as set forth in 18E.110.020 A. actually exist that indicate the potential for future erosion activity to occur; or

b.    Adequate engineering or structural measures have been provided through the submittal of a geological assessment – shoreline erosion geotechnical report that stabilizes the erosion hazard. Such engineering or structural measures must be completed, inspected and accepted for the area to be deemed stable.

4.    Riverine Erosion Hazard Areas. Riverine erosion hazard areas are located within the lateral extent of likely watercourse channel movement due to bank destabilization and erosion, rapid incision, and shifts in location of watercourse channels. Riverine erosion hazard areas are also referred to as channel migration zones (CMZs). Rivers and streams subject to erosion are regulated as a CMZ as listed in PCC 18E.70.020 B.4.

5.    Soil Erosion Hazard Areas. Soil erosion hazard areas are identified by the presence or absence of natural vegetative cover, soil texture condition, slope, and rainfall patterns, or man-induced changes to such characteristics that create site conditions which are vulnerable to erosion of the upper soil horizon. Soil erosion hazard areas are those areas with slopes of 20 percent or greater and that are classified as having severe, or very severe erosion potential by the Soil Conservation Service, United States Department of Agriculture (USDA).

(Ord. 2004-56s § 4 (part), 2004)

18E.110.030 Erosion Hazard Area Review Procedures.

A.    General Requirements.

1.    The Pierce County Critical Areas Atlas-Erosion Hazard Area Map provides an indication of where potential erosion hazard areas are located within the County. The actual presence or location of an erosion hazard area and/or additional potential erosion hazard area that have not been mapped, but may be present on or adjacent to a site, shall be determined using the procedures and criteria established in this Chapter.

2.    The Department will complete a review of the Critical Areas Atlas-Erosion Hazard Area Map, and any other source documents for any proposed regulated activity to determine whether the site for the regulated activity is located within a potential erosion hazard area.

3.    When the Department's maps, sources, or field investigations indicate that the site for a proposed regulated activity is located within a potential marine shoreline erosion hazard area, the Department shall require a geological assessment as outlined in PCC 18E.110.030 B. below. (See Figure 18E.110-2 in Chapter 18E.120 PCC.)

4.    When the Department's maps, sources, or field investigations indicate that the proposed project area for a regulated activity is located within a riverine erosion hazard area (channel migration zone). The standards set forth in Chapter 18E.70 PCC shall apply to riverine erosion hazard areas (channel migration zones).

5.    When the Department's maps, sources, or field investigations indicate that the proposed project area for a regulated activity is located within a potential soil erosion hazard area, the Department shall require submittal of an erosion control plan pursuant to the requirements set forth in Title 17A PCC, Construction and Infrastructure Regulations – Site Development and Stormwater Drainage.

6.    Applicants requesting to develop a bulkhead along a freshwater or marine shoreline shall be required to submit a geotechnical report. The geotechnical report shall comply with the requirements established in 18E.110.060 – Appendix C.

7.    Unless otherwise stated in this Chapter the critical area protective measure provisions contained in PCC 18E.10.080 shall apply.

B.    Geological Assessment. A geological assessment is a site investigation process to evaluate the on-site geology affecting a subject property and proposed development.

1.    Geological assessments shall be submitted to the Department for review and approval together with a shoreline erosion hazard area application.

2.    All geological assessments shall address the minimum requirements specified in Appendix A, B, or C, as applicable. The applicable assessment shall also include all supportive documentation for review including, but not limited to: 10-year and 120-year regression calculation data, historical mapping/air photos, published data and references, etc.

3.    Geological assessments shall be prepared, signed, and dated by a geotechnical professional (as defined in PCC 18E.10.060 and established in this Chapter) and the format shall be pre-approved by the Department.

4.    A geotechnical professional shall complete a field investigation and geological assessment to evaluate whether or not an active shoreline erosion hazard area exists within 200 feet of the site. (See Figure 18E.110-2 in Chapter 18E.120 PCC.)

a.    The geological assessment shall be submitted in the form of a geotechnical letter when the geotechnical professional finds that no active shoreline erosion hazard area exists within 200 feet of the site. The geotechnical letter shall meet the requirements contained in PCC 18E.110.060 – Appendix A.

b.    The geological assessment shall be submitted in the form of geotechnical evaluation when the geotechnical professional finds that an active shoreline erosion hazard area exists but is located more than 200 feet away from the proposed project area, and in their opinion will not impact the subject site. The geotechnical evaluation shall meet the requirements contained in PCC 18E.110.060 – Appendix B.

c.    The geological assessment shall be submitted in the form of a geotechnical report when the geotechnical professional finds that an active shoreline erosion hazard area exists within 200 feet of the proposed project area or when a geotechnical professional determines that structural shoreline modifications are necessary in order to construct or develop within an active shoreline erosion hazard area. The geotechnical report shall meet the requirements contained in PCC 18E.110.060 – Appendix C.

5.    The Department shall review the geological assessment and either:

a.    Accept the geological assessment and approve the application; or

b.    Reject the geological assessment and require revisions or additional information.

6.    A geological assessment for a specific site may be valid for a period of up to five years when the proposed land use activity and site conditions are unchanged. However, if surface and/or subsurface conditions associated with the site change during that five-year period, the applicant may be required to submit an amendment to the geological assessment.

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.

(Ord. 2013-45s4 § 4 (part), 2015; Ord. 2006-103s § 2 (part), 2006; Ord. 2004-56s § 4 (part), 2004)

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.

(Ord. 2013-45s4 § 4 (part), 2015; Ord. 2004-56s § 4 (part), 2004)

18E.110.050 Buffer Requirements.

A.    Determining Buffer Widths.

1.    The buffer width shall be measured on a horizontal plane from a perpendicular line established at the edge of the active shoreline erosion hazard area limits. (See Figure 18E.110-3 in Chapter 18E.120 PCC.)

2.    An undisturbed buffer of existing vegetation shall be required for an active shoreline erosion hazard area. The required standard buffer width is the greatest amount of the following distances:

a.    Fifty feet from all edges of the active shoreline erosion hazard area limits;

b.    A distance of one-third the height of the slope if the regulated activity is at the top of the slope and a distance of one-half the height if the regulated activity is at the bottom of the slope; or

c.    The minimum distance recommended by the geotechnical professional measured from the edge of the active shoreline erosion hazard area.

B.    Modification of Buffer Widths. The Department may require a larger buffer width than the standard buffer distance, as determined in subsection A. above, if any of the following are identified through the geological assessment process:

1.    The adjacent land is susceptible to severe erosion and erosion control measures will not effectively prevent adverse impacts.

2.    The area has a severe risk of slope failure or downslope stormwater drainage impacts.

(Ord. 2013-45s4 § 4 (part), 2015; Ord. 2004-56s § 4 (part), 2004)

18E.110.060 Appendices.

A.    Geological Assessment – Shoreline Erosion Hazard Geotechnical Letter.

B.    Geological Assessment – Shoreline Erosion Hazard Geotechnical Evaluation.

C.    Geological Assessment – Shoreline Erosion Hazard Geotechnical Report.

18E.110.060 – Appendix A
Geological Assessment – Shoreline Erosion Hazard Geotechnical Letter

A.    A geotechnical letter shall, at a minimum, include the following:

1.    The letter shall be labeled identifying the submittal as a "Shoreline Erosion Hazard Geotechnical Letter."

2.    The dates when the geological assessment was conducted. The date when the letter was prepared.

3.    The parcel number(s) of the site.

4.    Site address, if one has been assigned by the County.

5.    A brief description of the project (including the proposed land use) and a description of the area to be developed.

6.    A paragraph that states the following specific language:

"The services described in this report were prepared under the responsible charge of (Individual's Name). (Individual's Name) meets the qualifications contained in Section 18E.110.030 to prepare a geological assessment. (Individual's Name) understands the requirements of the current Erosion Hazard Area Chapter 18E.110 and the definitions of the applicable terms contained within Chapter 18.25. Individuals under the responsible charge of (Individual's Name) have performed a shoreline erosion hazard geological assessment, conducted a field investigation, and researched available historic records on the above referenced site. In my opinion, the scope of services completed for this project is adequate to meet the requirements of this Title and it does not appear that an active shoreline erosion hazard area exists within 200 feet of the site."

7.    The name, mailing address, and telephone number of the geotechnical professional who prepared the letter.

8.    The name, mailing address, and telephone number of the property owner.

B.    The geotechnical letter shall be prepared under the responsible charge of a geotechnical professional(s) and be signed, sealed and dated by the geotechnical professional(s).

(Ord. 2004-56s § 4 (part), 2004)

18E.110.060 – Appendix B
Geological Assessment – Shoreline Erosion Hazard Geotechnical Evaluation

A.    A geotechnical evaluation shall, at a minimum, include the following:

1.    The cover letter for the document shall clearly identify the submittal as a "Shoreline Erosion Hazard Geotechnical Evaluation."

2.    The dates when the geological assessment was conducted. The date when the evaluation was prepared.

3.    The parcel number(s) of the site.

4.    Site address, if one has been assigned by the County.

5.    A detailed description of the project (including the proposed land use) and a description of the area to be developed.

6.    A summary of the results, conclusions, and recommendations resulting from the geological assessment, as set forth in PCC 18E.110.030 B.

7.    An accurate site plan drawn at a scale of 1" = 20', 1" = 30', 1" = 50' (or other scale deemed appropriate by the Department) is required. The Department may require that the site plan information listed below be based on a field survey by a licensed surveyor. The site plan shall include:

a.    The limits/location of the active shoreline erosion hazard area(s) set forth in PCC 18E.110.020 B.2.

b.    The limits of the required shoreline erosion hazard buffer based upon the requirements set forth in PCC 18E.110.050 A.

c.    The limits/location of the Shoreline Erosion Hazard Management Area.

d.    The limits/location of the 120 year regression area.

e.    The location of any existing structures, utilities, on-site septic systems, wells, and stormwater management facilities.

f.    The location of any proposed structures, utilities, on-site septic systems, wells, and stormwater management facilities.

g.    The full geographical limits of the proposed project area (area to be developed).

h.    Dimension of the closest distance between the identified active shoreline hazard area boundary and the proposed project area.

i.    Dimension of the closest distance between the 120-year regression line and the proposed project area.

j.    Existing contours on the site at 2-foot intervals.

k.    Property lines for the site.

l.    North arrow and scale.

8.    A paragraph that states the following specific language:

"The services described in this report were prepared under the responsible charge of (Individual's Name). (Individual's Name) meets the qualifications contained in Section 18E.110.030 to prepare a geological assessment. (Individual's Name) understands the requirements of the current Erosion Hazard Area Chapter 18E.110 and the definitions of the applicable terms contained within Chapter 18.25. Individuals under the responsible charge of (Individual's Name) have performed a shoreline erosion hazard geological assessment, conducted a field investigation, and researched available historic records on the above referenced site. In my opinion, the scope of services completed for this project is adequate to meet the requirements of this Title and it does not appear that an active shoreline erosion hazard area exists within 200 feet of the proposed project area."

9.    The name, mailing address, and telephone number of the geotechnical professional who prepared the evaluation.

10.    The name, mailing address, and telephone number of the property owner.

B.    The geotechnical evaluation shall be prepared under the responsible charge of a geotechnical professional(s) and be signed, sealed and dated by the geotechnical professional(s).

(Ord. 2004-56s § 4 (part), 2004)

18E.110.060 – Appendix C
Geological Assessment – Shoreline Erosion Hazard Geotechnical Report

A.    A geotechnical report shall, at a minimum, include the following:

1.    The cover letter for the document shall clearly identify the submittal as a "Shoreline Erosion Hazard Geotechnical Report."

2.    The dates when the geological assessment was conducted. The date when the report was prepared.

3.    The parcel number(s) of the site.

4.    Site address, if one has been assigned by the County.

5.    A detailed description of the project (including the proposed land use) and a description of the area to be developed.

6.    A summary of the results, conclusions, and recommendations resulting from the geological assessment, as set forth in PCC 18E.110.030 B. The summary shall specifically address:

a.    In the case of proposed development, whether it is possible given the physical constraints of the property (size, shape, building setbacks, utility requirements, etc.) to locate the proposed development outside of the 120-year area of regression based on natural shoreline processes.

b.    In the case of proposed development, if it is not possible to locate the development outside of the 120-year area of regression (based on natural processes), evaluation whether beach nourishment and/or soft armoring techniques can be used to slow the rate of regression such that the proposed development is no longer within the 120-year regression area.

c.    Whether any existing structures will be threatened within the next ten years or whether the buildability of an undeveloped site will be threatened within the next ten years, if hard armoring is not provided.

d.    Evaluate whether any proposed shoreline erosion protection measures will cause an increase in the rate of regression on neighboring properties.

7.    An accurate site plan drawn at a scale of 1" = 20', 1" = 30', 1" = 50' (or other scale deemed appropriate by the Department) is required. The Department may require that the site plan information listed below be based on a field survey by a licensed surveyor. The site plan shall include:

a.    The limits/location of the active shoreline erosion hazard area(s) set forth in PCC 18E.110.020 B.2.

b.    The limits of the required shoreline erosion hazard buffer based upon the requirements set forth in PCC 18E.110.050 A.

c.    The limits/location of the Shoreline Erosion Hazard Management Area.

d.    The limits/location of the 120-year regression area based on natural shoreline processes and, if applicable, based upon proposed shoreline protection measures.

e.    The location of any existing structures, utilities, on-site septic systems, wells, and stormwater management facilities.

f.    The location of any proposed structures, utilities, on-site septic systems, wells, and stormwater management facilities.

g.    The full geographical limits of the proposed project area (area to be developed).

h.    Dimension of the closest distance between the identified active shoreline hazard area boundary and the proposed project area.

i.    Dimension of the closest distance between the 120-year regression line and the proposed project area.

j.    Existing contours on the site at 2-foot intervals.

k.    Property lines for the site.

l    North arrow and scale.

8.    A discussion of any proposed shoreline protection measures including design and construction drawings is required.

9.    A list of references utilized in preparation of the report.

10.    The name, mailing address, and telephone number of the geotechnical professional(s) who prepared the report.

11.    The name, mailing address, and telephone number of the property owner.

B.    The geotechnical report shall be prepared under the responsible charge of a geotechnical professional(s) and be signed, sealed and dated by the geotechnical professional(s).

C.    The Department may request a geotechnical professional to provide additional information in the geotechnical report based upon existing conditions, changed conditions, or unique circumstances occurring on a case by case basis.

D.    Geotechnical reports shall be in conformance with a format that is pre-approved by the Department.

(Ord. 2004-56s § 4 (part), 2004)