These regulations are adopted for the following purposes:

A.

To implement the goals and policies for the Growth Management Act, RCW Chapter 36.70A;

B.

To maintain the functions and values of critical areas and enhance the quality of habitat to support the sustenance of native plants and animals;

C.

To balance property owner interests with the public interest;

D.

To promote biodiversity within critical areas and buffers by encouraging planting with mostly native vegetation;

E.

To establish review criteria for land use reviews that maintain and improve the ecological health of wetlands, watercourses and Lake Washington;

F.

To establish standards for new development that avoid increasing the risk of harm to people, property, and public infrastructure from natural hazards;

G.

To protect the functions and values of fish and wildlife habitat conservation areas, including wetlands, watercourses and habitat for priority species and species of local importance, through the use of buffers;

H.

To increase the safety of development within and adjacent to geologically hazardous areas through the use of buffers;

I.

To require mitigation measures when unavoidable impacts to critical areas are proposed;

J.

To establish tools to ensure that protection and mitigation measures are applied and maintain ecological value and function consistent with the provisions of this chapter;

K.

To avoid impact to the critical areas where possible, and, if avoidance is not reasonably possible, minimize impacts to critical areas and buffers to the greatest extent feasible, and mitigate any remaining impacts;

L.

To encourage the restoration of existing compromised critical areas; and

M.

To minimize negative impacts from the built environment on the functions and values of critical areas.

(Ord. 19C-05 § 1 (Exh. A))

A.

Except as specifically exempted by section 19.07.120, exemptions, these regulations apply to land uses, development activity, and all structures and facilities within the city of Mercer Island that contain any of the following critical areas and/or their buffers, as defined in chapter 19.16:

1.

Geologically hazardous areas;

2.

Fish and wildlife habitat conservation areas;

3.

Watercourses; and

4.

Wetlands.

B.

The city shall not approve any development proposal or otherwise issue any authorization to alter the condition of any land, water or vegetation or to construct or alter any structure or improvement without first assuring compliance with the requirements of this chapter or determining that this chapter is not applicable to the development.

C.

Approval of a development proposal pursuant to the provisions of this chapter does not discharge the applicant of the obligation to comply with the provisions of this chapter.

(Ord. 19C-05 § 1 (Exh. A))

A.

Interpreting multiple regulations. If more than one regulation applies to a given property, then the regulation that provides the greatest protection to critical areas shall apply.

B.

Other jurisdictions. Nothing in these regulations eliminates or otherwise affects the responsibility of an applicant or property owner to comply with all other applicable local, state, and federal regulations and required permits.

C.

SEPA compliance. Nothing in these regulations or the decisions made pursuant to these regulations affects the authority of the city to review, condition, and deny projects under the State Environmental Policy Act, RCW Chapter 43.21C.

(Ord. 19C-05 § 1 (Exh. A))

The city is authorized to adopt administrative rules and regulations that are consistent with this chapter and necessary and appropriate for its implementation. The city is also authorized to prepare and require the use of forms to facilitate the chapter's administration.

(Ord. 19C-05 § 1 (Exh. A))

A.

Unless otherwise indicated in this title, the applicant shall be responsible for the initiation, preparation, submission, and expense of all required reports, assessments, studies, plans, reconnaissances, or other work prepared in support of or necessary to review the application.

B.

The applicant shall be responsible for all applicable fees as established in the city's fee schedule, consultant review fees, and peer review fees.

(Ord. 19C-05 § 1 (Exh. A))

Approximate locations of critical areas in the city of Mercer Island are depicted on citywide maps displayed in the city's GIS database, as amended. Field verification and, if the city deems appropriate, evaluation and mapping by a qualified professional of the location of critical areas will be required to determine the location and type of critical area on a given site.

(Ord. 19C-05 § 1 (Exh. A))

A.

The applicant shall disclose to the city the presence of critical areas on the development proposal site and any mapped or identifiable critical areas within the distance equal to the largest potential required buffer applicable to the development proposal on the development proposal site.

B.

The owner of any property containing critical areas and/or buffers on which a development proposal is submitted, except a public right-of-way or the site of a permanent public facility, shall file a notice approved by the city with the records and elections division of King County. The notice shall inform the public of the presence of critical areas, buffers and/or mitigation sites on the property, of the application of the city's critical areas code to the property and that limitations on actions in or affecting such critical areas and/or buffers may exist. The notice shall run with the land in perpetuity.

C.

The applicant shall submit proof to the city that the notice has been recorded prior to approval of a development proposal for the property or, in the case of subdivisions, short subdivisions, and binding site plans, at or before recording of the final subdivision, short subdivision, or binding site plan.

D.

Notices on title may be removed or amended, whichever is applicable, at a property owner's request, after approval by the city if it is documented that the information contained in an existing notice is no longer accurate because a critical area has changed, for example, in its type or location, or if the notice is proposed to be replaced with a notice containing updated information.

(Ord. 19C-05 § 1 (Exh. A))

A.

Hold harmless/indemnification agreement and covenant not to sue, performance guarantees, performance bonds, insurance. An applicant for a permit within a critical area shall comply with the requirements of section 19.01.060.

B.

Timing. All alterations or mitigation to critical areas shall be completed prior to the final inspection and occupancy of a project.

C.

Maintenance and monitoring.

1.

Maintenance and monitoring shall be required for at least five years from the date of project completion if the code official determines such condition is necessary to ensure mitigation success and critical area protection.

2.

A bond or assignment of funds pursuant to section 19.01.060(C) may be required to guarantee that approved mitigation plans will be undertaken and completed to the city's satisfaction.

3.

When monitoring is required, site visits and reporting shall be required two times per year for each of the first two years and once every 12 months for the subsequent years of the monitoring period.

4.

Where monitoring reveals a significant difference from predicted impacts or a failure of protection measures, the applicant shall be responsible for appropriate corrective action, which may be subject to further monitoring.

D.

Compliance with mitigation requirements. In cases where mitigation has been completed, but no monitoring reports have been submitted to the city, the applicant shall submit as-built drawings and yearly monitoring reports to the city until at least two consecutive annual reports document that all performance standards from the approved mitigation plan have been met.

E.

Seasonal limitations. Land clearing, grading, filling, and foundation work may be limited to only certain times of year, pursuant to section 19.07.160(F)(2).

F.

Suspension of work. If the alteration does not does not comply with the permit or applicable codes, including controls for water quality, erosion and sedimentation, the city may suspend further work on the site until such standards are met. Compliance with all requirements of this chapter is required pursuant to section 19.15.210.

G.

A critical area study, as described in section 19.07.110, completed over five years prior to application submittal date, shall be field verified by a qualified professional to determine whether the study accurately provides information required by the Code, and, if not, the study shall be updated or completed according to the current best available science.

(Ord. 19C-05 § 1 (Exh. A))

This section describes the purpose and procedures by which the city will review and authorize development and verify consistency with this chapter.

A.

Critical area review 1.

1.

The purpose of a critical area review 1 is to review:

a.

Activities listed as modifications in section 19.07.130, modifications;

b.

Verification of the presence or absence of a critical area; or

c.

Verification of the delineation and/or type of wetland or watercourse.

2.

Review timing and sequence.

a.

If a building permit is required for the proposed scope of work associated with the critical area review 1, then the substance of the review shall take place concurrently with the building permit review and no separate land use review application is required.

b.

If no building permit is required for the proposed scope of work associated with the critical area review 1, then the review shall take place according to the procedures required for a Type 1 land use review.

3.

Requirements for a complete application.

a.

Completed development application coversheet.

b.

Project narrative, describing the proposed scope of work.

c.

Scaled site plan showing the proposed work.

d.

Any additional information required by the city to confirm compliance with this title.

B.

Critical area review 2.

1.

The purpose of a critical area review 2 is to review critical area studies and mitigation plans in support of proposed buffer averaging and reduction of wetland and watercourse buffers.

2.

Review timing and sequence.

a.

When development and/or activity within a wetland, watercourse, fish and wildlife habitat conservation area or buffer associated with these critical area types is proposed, a critical area review 2 is required to be reviewed and approved prior to construction authorization.

b.

When development and/or activity is proposed on a site containing only geologically hazardous areas, an applicant has the option of either:

i.

Applying for a critical area review 2 in advance of construction permits, using the procedures required for a Type 3 land use review; or

ii.

Requesting consolidation of the review of geologically hazardous areas together with construction permit review.

c.

When development and/or activity is proposed on a site containing geologically hazardous areas and one or more of the critical area types listed in subsection (B)(2)(a) of this section or the associated buffer of one of those critical areas, a critical area review 2 reviewing all critical areas is required to be reviewed and approved prior to construction authorization, using the procedures required for a Type 3 land use review.

3.

Requirements for a complete application include:

a.

A completed development application coversheet;

b.

A critical area study, meeting the requirements of section 19.07.110, critical area study; and

c.

Additional information required by the city to confirm compliance with this title.

C.

Reasonable use exceptions shall be reviewed using the criteria in section 19.07.140, using the procedures required for a Type 4 land use review.

D.

Public agency exceptions shall be reviewed using the criteria in section 19.07.150, using the procedures required for a Type 3 land use review.

(Ord. 19C-05 § 1 (Exh. A))

Except as otherwise provided in this chapter, an applicant for a development proposal or activity shall implement the following sequential measures, listed below in order of preference, to avoid, minimize, and mitigate impacts to environmentally critical areas and associated buffers. Applicants shall document how each measure has been addressed before considering and incorporating the next measure in the sequence:

A.

Avoiding the impact altogether by not taking a certain action or parts of an action. The applicant shall consider reasonable, affirmative steps and make best efforts to avoid critical area impacts. However, avoidance shall not be construed to mean mandatory withdrawal or denial of the development proposal or activity if the proposal or activity is an allowed, permitted, or conditional use in this title. In determining the extent to which the proposal should be redesigned to avoid the impact, the code official may consider the purpose, effectiveness, engineering feasibility, commercial availability of technology, best management practices, safety and cost of the proposal and identified changes to the proposal. Development proposals should seek to avoid, minimize and mitigate overall impacts based on the functions and values of all of the relevant critical areas and based on the recommendations of a critical area study. If impacts cannot be avoided through redesign, use of a setback deviation pursuant to section 19.06.110(C), or because of site conditions or project requirements, the applicant shall then proceed with the sequence of steps in subsections B through E of this section;

B.

Minimizing impacts by limiting the degree or magnitude of the action and its implementation, using a setback deviation pursuant to section 19.06.110(C), using appropriate technology, or by taking affirmative steps to avoid or reduce impacts;

C.

Rectifying the impact by repairing, rehabilitating, or restoring the affected environment;

D.

Reducing or eliminating the impact over time by preservation and maintenance operations during the life of the action;

E.

Compensating for the impact by replacing, enhancing, or providing substitute resources or environments; and/or

F.

Monitoring the impact and taking appropriate corrective measures to maintain the integrity of compensating measures.

(Ord. 19C-05 § 1 (Exh. A))

A.

A critical area study shall be required when a development proposal will result in an alteration to one or more critical areas or critical area buffers or when required to determine the potential impact to a critical area.

B.

The critical area study shall be in the form of a written report supported by graphic information prepared by a qualified professional using guidance based on the best available science consistent with the standards in WAC Chapter 365-195 and shall contain the following items, as applicable to adequately evaluate the proposal, proposed alterations, and mitigation:

1.

Disclosure of the presence of critical areas, including a delineation and type or category of critical area, on the development proposal site and any mapped or identifiable critical areas on or off site within the distance equal to the largest potential required buffer applicable to the development proposal area on the applicant's property;

2.

A topographic and boundary survey;

3.

A statement specifying the accuracy of the report and all assumptions made and relied upon;

4.

A description of the methodologies used to conduct the critical area study, including references;

5.

A scale map of the development proposal site;

6.

Photographic records of the site before the proposed alteration occurs;

7.

An assessment of the probable effects to critical areas and associated buffers, including impacts caused by the development proposal and associated alterations to the subject property and impacts to other properties and any critical areas or buffers located on them resulting from the development of the site and the proposed development;

8.

A description of mitigation sequencing implementation described in section 19.07.100 including steps taken to avoid and minimize critical areas impacts to the greatest extent feasible;

9.

Detailed studies, as required by this chapter, for individual critical area types in order to ensure critical area protection;

10.

Assessment of potential impacts that may occur on adjacent sites, such as sedimentation or erosion, where applicable; and

11.

A post-design memorandum prepared by a qualified professional confirming that the proposed improvements comply with the design recommendations.

C.

The critical area study requirement may be waived or modified if the applicant demonstrates that the development proposal will not have an impact on the critical area or its buffer in a manner contrary to the purposes and requirements of this chapter.

(Ord. 19C-05 § 1 (Exh. A))

A.

Activities listed as exempt in this section do not require review for compliance with this chapter, provided they are otherwise consistent with the provisions of other city, state, and federal laws and requirements.

B.

An exemption does not give permission to degrade a critical area or ignore risk from natural hazards.

C.

All temporary and permanent impacts to critical areas and buffers shall be mitigated.

D.

The following activities are exempt from review and compliance with this chapter, provided all activities shall use reasonable methods to avoid and, if avoidance is not possible, minimize impacts to critical areas and buffers to the greatest extent feasible consistent with section 19.07.100, mitigation sequencing:

1.

Minor expansion of existing right-of-way improvements, including public streets, bike lanes, shoulders, trails, sidewalks, and open space, following consultation with the code official;

2.

Minor expansion of public utility structures and conveyance systems and their associated facilities including service lines, pipes, mains, poles, equipment and appurtenances, both above and below ground, following consultation with the code official;

3.

Site investigative work and studies. Site investigative work and studies necessary for development proposals, including geotechnical tests, water quality studies, wildlife studies, surveys, soil logs, and critical area investigations within areas accessed by foot; provided the following criteria are met:

a.

Impacts to critical areas and buffers shall be minimized; and

b.

Disturbed areas shall be restored with native vegetation as soon as the investigative work is complete; and

4.

Watercourse restoration and pipe extensions installed by a public agency, provided the steps in section 19.07.100, mitigation sequencing, are addressed.

E.

The following activities are exempt from city review and approval but must comply with the standards of this chapter:

1.

Repair and maintenance of existing right-of-way improvements. Repair, maintenance, reconstruction and replacement of existing right-of-way improvements, including public streets, bike lanes, shoulders, trails, sidewalks, and open space.

2.

Repair and maintenance of existing utility facilities. Repair, maintenance, reconstruction and replacement of public utility structures and conveyance systems and their associated facilities, including but not limited to service lines, pipes, mains, poles, equipment and appurtenances, both above and below ground.

3.

Noxious weed removal. Removal of noxious weeds, provided:

a.

All disturbed soils are stabilized and revegetated with appropriate native vegetation; and

b.

The area from which noxious weeds are removed is limited to 1,000 square feet.

4.

Maintenance of existing landscaping. Landscape maintenance of legally established lawns and gardens including mowing, pruning, weeding, and planting; provided, that such activities are consistent with the following provisions:

a.

Landscaping is not expanded any further into critical areas or buffers;

b.

Erosion control measures are implemented when soils have been disturbed;

c.

Groundcover voids that result from the removal of noxious weeds shall be revegetated with regional native plants;

d.

Removal of noxious weeds and other restoration work shall be undertaken with hand labor, including handheld mechanical tools, unless the King County Noxious Weed Control Board best management practice specifically prescribes the use of riding mower, light mechanical cultivating equipment, or herbicide or biological control methods;

e.

Herbicide use is in accordance with federal and state law; and

f.

Landscaping does not include the removal of large or exceptional trees.

5.

Survey and boundary markers. Placement or modification of survey and boundary markers.

6.

Temporary alterations in response to emergencies that threaten the public health, safety, and welfare or that pose an imminent risk of damage to private property, provided the following criteria are met:

a.

The person undertaking such an action shall notify the code official in writing within one business day following commencement of the emergency activity;

b.

Within 15 calendar days of the commencement of the emergency activity, the person undertaking such an action shall submit a complete application for all necessary approvals to authorize the alterations made and proposed in response to the emergency. The code official may allow additional time up to 180 calendar days for submittal of a complete application if the applicant requests an extension for a specific period of time. The code official may grant additional time extensions beyond 180 calendar days when multiple property owners or litigation is involved and when requested by the applicant;

c.

The person undertaking such an action shall mitigate all impacts caused by the alteration and associated restoration activities, including intentional or unintentional alterations to all critical areas and buffers; and

d.

A qualified professional shall supervise all alterations made to critical areas.

7.

Passive outdoor activities. When it can be demonstrated that there will be no undue adverse effect, the following activities may be allowed within critical areas and their buffers: educational activities, scientific research, and outdoor recreational activities, including but not limited to interpretive field trips, bird watching, and beach access including water recreation-related activities. This exemption does not authorize any construction.

(Ord. 19C-05 § 1 (Exh. A))

Activities of the following types may be authorized with approval of an application for a critical area review 1. The activities in this section are exempt from the development standards in subsequent sections within this chapter; provided, that additional measures to protect life and property or to protect environmental quality may be required.

A.

Addition to or reconstruction of an existing legally established structure or building within a critical area and/or buffer constructed on or before January 1, 2005, provided the following criteria are met:

1.

The seasonal limitations on land clearing, grading, filling, and foundation work described in section 19.07.160(F)(2) shall apply.

2.

Additions shall be allowed if all of the following criteria are met:

a.

The structure is enlarged not more than a cumulative total of 200 square feet larger than its footprint as of January 1, 2005;

b.

If the existing, legally established structure is located over or within a wetland or watercourse, no further expansion within the wetland or watercourse is allowed;

c.

If the existing legally established structure is located within a wetland or watercourse buffer, the addition may be no closer to the wetland or watercourse than a distance equal to 75 percent of the applicable standard buffer and must also be no closer to the watercourse or wetland than the existing structure;

d.

A critical area study approved by the city demonstrates that impacts have been avoided or minimized and mitigated consistent with section 19.07.100, mitigation sequencing;

e.

If the modification or addition is proposed within a geologically hazardous area or associated buffer, a qualified professional provides a statement of risk consistent with section 19.07.160(B)(3).

3.

Reconstruction of legally established nonconforming structures shall meet the standards in section 19.01.050. The code official may require a critical area study and mitigation plan addressing temporary impacts to critical areas and buffers.

4.

Demolition. Removal of structures in watercourse and wetland buffers and geologically hazardous areas, provided:

a.

Site disturbance is limited to the existing access and building footprint;

b.

There is no site disturbance within or to wetlands or watercourses;

c.

All soils are stabilized and the area is revegetated with appropriate native vegetation; and

d.

Necessary building permits are obtained.

B.

Restoration and enhancement activities involving site disturbance over 1,000 square feet, provided the following criteria are met:

1.

Erosion control measures are implemented when soils have been disturbed;

2.

Groundcover voids that result from the removal of noxious weeds shall be revegetated with regional native plants;

3.

Removal of noxious weeds and other restoration work shall be undertaken with hand labor, including handheld mechanical tools, unless the King County Noxious Weed Control Board best management practice specifically prescribes the use of riding mower, light mechanical cultivating equipment, or herbicide or biological control methods; and

4.

Herbicide use is in accordance with federal and state law.

C.

Storm water retrofit facilities installed pursuant to the city's NPDES Phase II permit.

D.

Any pruning shall not be detrimental to tree health and shall be consistent with International Society of Arboriculture standards and completed under the supervision of a qualified arborist.

(Ord. 19C-05 § 1 (Exh. A))

A.

If the application of this chapter will deny all reasonable use of the owner's property, then the applicant may apply to the community planning and development department for an exception from the requirements of this chapter in accordance with the provisions for Type IV reviews in chapter 19.15. The hearing examiner may approve the application for a reasonable use exception only if the development proposal meets all of the following criteria:

1.

The application of this chapter would deny all reasonable use of the property;

2.

There is no other reasonable use with less impact on the critical area;

3.

Any alteration to critical areas and associated buffers is the minimum necessary to allow for reasonable use of the property;

4.

The proposal does not pose an unreasonable threat to the public health, safety, or welfare on or off the development proposal site;

5.

The proposal is consistent with the purpose of this chapter and the public interest; and

6.

The inability of the applicant to derive reasonable use of the property is not the result of actions by the current or prior property owner.

B.

The hearing examiner may approve, approve with conditions, or deny the request based on the proposal's ability to comply with all of the above criteria. The applicant has the burden of proof in demonstrating that the above criteria are met.

(Ord. 19C-05 § 1 (Exh. A))

If the application of this chapter would prohibit a development proposal by a public agency, the agency may apply for an exception pursuant to this section:

A.

The public agency shall provide project documents such information as needed for the code official to issue a decision, including, but not limited to, permit applications to other agencies, critical area studies, SEPA documents, and other materials.

B.

The code official may approve alterations to critical areas, buffers and critical area setbacks by an agency or utility when those alterations are not otherwise able to meet all of the standards in this chapter, and when the criteria in subsections (B)(1) through (B)(5) of this section are demonstrated to be met.

1.

The activity or proposed development is described in an adopted city plan or project list, or has otherwise received city council approval;

2.

There is no other reasonable alternative to the activity or proposed development with less impact on the critical area. In determining what is a reasonable alternative to a proposed development, alteration or activity, the code official may consider the purpose, effectiveness, engineering feasibility, commercial availability of technology, best management practices, safety and cost of the alternative action or proposal. Reasonable alternatives are those that are capable of being carried out, taking into consideration the overall project purposes, needs, and objectives;

3.

The activity or development proposal is designed to avoid or minimize and mitigate the impact on critical areas and associated buffers consistent with the avoidance and mitigation sequencing requirements in section 19.07.100, mitigation sequencing;

4.

The proposal does not pose an unreasonable threat to the public health, safety, or welfare on or off the development proposal site; and

5.

The proposal is consistent with other applicable regulations and standards.

(Ord. 19C-05 § 1 (Exh. A))

A.

Designation and typing. Geologically hazardous areas are lands that are susceptible to erosion, landslides, seismic events, or other factors as identified by WAC 365-190-120. These areas may not be suited for development activities because they may pose a threat to public health and safety. Areas susceptible to one or more of the following types of hazards shall be designated as geologically hazardous areas: landslide hazard areas, seismic hazard areas, and erosion hazard areas.

B.

General review requirements. Alteration within geologically hazardous areas or associated buffers is required to meet the standards in this section, unless the scope of work is exempt pursuant to section 19.07.120, exemptions, or a critical area review 1 approval has been obtained pursuant to section 19.07.090(A).

1.

When an alteration within a landslide hazard area, seismic hazard area or buffer associated with those hazards is proposed, the applicant must submit a critical area study concluding that the proposal can effectively mitigate risks of the hazard. The study shall recommend appropriate design and development measures to mitigate such hazards. The code official may waive the requirement for a critical area study and the requirements of subsections (B)(2) and (B)(3) of this section when he or she determines that the proposed development is minor in nature and will not increase the risk of landslide, erosion, or harm from seismic activity, or that the development site does not meet the definition of a geologically hazardous area.

2.

Alteration of landslide hazard areas and seismic hazard areas and associated buffers may occur if the critical area study documents find that the proposed alteration:

a.

Will not adversely impact other critical areas;

b.

Will not adversely impact the subject property or adjacent properties;

c.

Will mitigate impacts to the geologically hazardous area consistent with best available science to the maximum extent reasonably possible such that the site is determined to be safe; and

d.

Includes the landscaping of all disturbed areas outside of building footprints and installation of hardscape prior to final inspection.

3.

Alteration of landslide hazard areas, seismic hazard areas and associated buffers may occur if the conditions listed in subsection (B)(2) of this section are satisfied and the geotechnical professional provides a statement of risk matching one of the following:

a.

An evaluation of site-specific subsurface conditions demonstrates that the proposed development is not located in a landslide hazard area or seismic hazard area;

b.

The landslide hazard area or seismic hazard area will be modified or the development has been designed so that the risk to the site and adjacent property is eliminated or mitigated such that the site is determined to be safe;

c.

Construction practices are proposed for the alteration that would render the development as safe as if it were not located in a geologically hazardous area and do not adversely impact adjacent properties; or

d.

The development is so minor as not to pose a threat to the public health, safety and welfare.

C.

Development standards—Landslide hazard areas. Development is allowed within landslide hazard areas and associated buffers, when the following standards are met:

1.

A critical area study shall be required for any alteration of a landslide hazard area or associated buffer;

2.

Buffers shall be applied as follows. When more than one condition applies to a site, the largest buffer shall be applied:

a.

Steep slopes. Buffer widths shall be equal to the height of a steep slope, but not more than 75 feet, and applied to the top and toe of slopes;

b.

Shallow landslide hazard areas shall have minimum 25-foot buffers applied in all directions; and

c.

Deep-seated landslide hazard areas shall have 75-foot buffers applied in all directions.

D.

Development standards—Seismic hazard areas. When development is proposed within a seismic hazard area:

1.

A critical area study shall be required and shall include an evaluation by a qualified professional for seismic engineering and design, a determination of the magnitude of seismic settling that could occur during a seismic event, and a demonstration that the risk associated with the proposed alteration is within acceptable limits or that appropriate construction methods are provided to mitigate the risk of seismic settlement such that there will be no significant impact to life, health, safety, and property.

2.

Identification of seismic hazard areas. Seismic hazard areas shall be identified by a qualified professional who references and interprets information in the U.S. Geological Survey Active Faults Database, performs on-site evaluations, or applies other techniques according to best available science.

3.

When development is proposed on a site with an active fault, the follow provisions shall apply:

a.

A 50-foot minimum buffer shall be applied from latest Quaternary, Holocene, or historical fault rupture traces as identified by the United States Geological Survey or Washington Geological Survey map databases or by site investigations by licensed geologic professionals with specialized knowledge of fault trenching studies; or

b.

Mitigation sequencing shall be incorporated into the development proposal as recommended based on geotechnical analysis by a qualified professional to prevent increased risk of harm to life and/or property.

E.

Development standards—Erosion hazard areas.

1.

All development proposals shall demonstrate compliance with chapter 15.09, storm water management program.

2.

No development or activity within an erosion hazard area may create a net increase in geological instability on or off site.

F.

Development standards—Additional criteria for specific activities.

1.

Trail building within geologically hazardous areas shall be subject to the following:

a.

Trail surfaces shall be constructed of pervious materials and may not be wider than five feet; and

b.

Trails shall be located to minimize the need for tree removal.

2.

Land clearing, grading, filling, and foundation work within: (a) an erosion hazard area, when 2,000 square feet or more of site disturbance is proposed, and/or (b) a landslide hazard area are not permitted between October 1 and April 1.

a.

The code official may grant a waiver to this seasonal development limitation if the applicant provides a critical area study for the site concluding that:

i.

Geotechnical slope stability concerns, erosion and sedimentation impacts can be effectively controlled on site consistent with adopted storm water standards; and

ii.

The proposed construction work will not subject people or property, including areas off site, to an increased risk of associated impacts.

b.

As a condition of the waiver, the code official may require erosion control measures, restoration plans, an indemnification, a release agreement and/or performance bond.

c.

If site activities result in erosion impacts or threaten water quality standards, the city may suspend further work on the site and/or require remedial action.

d.

Failure to comply with the conditions of an approved waiver shall subject the applicant to code compliance pursuant to chapter 6.10, code compliance, including but not limited to civil penalties and permit suspension.

(Ord. 19C-05 § 1 (Exh. A))

A.

Designation and typing. Fish and wildlife habitat conservation areas include the following:

1.

Areas where state or federally listed endangered, threatened, sensitive, or candidate species, or species of local importance, have primary association;

2.

Priority habitats and areas associated with priority species identified by the Washington State Department of Fish and Wildlife;

3.

Areas used by bald eagles for foraging, nesting, and roosting, or within 660 feet of a bald eagle nest;

4.

Watercourses and wetlands and their buffers; and

5.

Biodiversity areas.

B.

General review requirements.

1.

When development is proposed in the areas described in subsection A of this section, the applicant shall, unless the proposal is specifically exempt pursuant to section 19.07.120, submit a wildlife habitat assessment in the form of a critical area study prepared by a qualified professional including the following information:

a.

Identification of the species referenced in subsection A of this section that has a primary association with habitat on or in the vicinity of the site;

b.

Extent of wildlife habitat areas, including acreage, and required buffers based on the species;

c.

Vegetative, faunal, and hydrologic characteristics;

d.

Evaluation of direct and indirect potential impacts on habitat by the project, including potential impacts to water quality;

e.

A discussion of any federal, state, or local special management recommendations, including Washington State Department of Fish and Wildlife habitat management recommendations that have been developed for the species or habitats; and

f.

A discussion of avoidance, minimization, and mitigation of impacts pursuant to section 19.07.100.

C.

Development standards.

1.

Development proposals shall implement wildlife and habitat protection measures identified in the wildlife habitat assessment.

2.

Development proposals within areas used by bald eagles for foraging, nesting, or roosting, or within 660 feet of a bald eagle nest as identified by a critical area study, shall follow the requirements of the U.S. Fish and Wildlife's National Bald Eagle Management Guidelines (2007).

(Ord. 19C-05 § 1 (Exh. A))

A.

Designation and typing. Watercourses shall be classified by the following types:

1.

Type S (there are no known Type S watercourses on Mercer Island);

2.

Type F;

3.

Type Np;

4.

Type Ns; and

5.

Piped.

B.

General review requirements.

1.

Development within watercourses and/or associated buffers is prohibited unless one of the following conditions applies:

a.

The proposed activity is specifically exempt pursuant to section 19.07.120;

b.

A critical area review 1 application is reviewed and approved for one of the modifications in section 19.07.130; or

c.

The proposed activity is permitted under subsection D of this section, development standards—additional criteria for specific activities.

C.

Development standards—Buffers.

1.

The following minimum buffers shall be established from the ordinary high water mark or from the top of the bank if the ordinary high water mark cannot be identified:

2.

Neither lot coverage nor hardscape shall be permitted within a watercourse or watercourse buffer except as specifically provided in this chapter.

3.

Any watercourse adjoined by a riparian wetland or other contiguous critical area shall have the buffer required for the stream type involved or the buffer that applies to the wetland or other critical area, whichever is greater.

4.

Buffer averaging. Buffer width averaging shall be allowed provided the following requirements are met:

a.

The applicant has demonstrated how impacts will be minimized and that avoidance has been addressed consistent with section 19.07.100, mitigation sequencing;

b.

The applicant has demonstrated how all proposed impacts have been mitigated consistent with subsection E of this section, mitigation requirements, and will not result in a loss of ecological function;

c.

The proposed buffer width is not less than 75 percent of the standard buffer width at any point; and

d.

The total area of the buffer is equal to the area required without averaging.

Figure 1: Example of Buffer Averaging

5.

Buffer reduction. Buffer width reduction shall be allowed provided the following requirements are met:

a.

The applicant has demonstrated that buffer averaging would not feasibly allow development;

b.

The applicant has demonstrated how impacts will be minimized and that avoidance has been addressed consistent with section 19.07.100, mitigation sequencing;

c.

The applicant has demonstrated how all proposed impacts have been mitigated consistent with subsection E of this section and will not result in a loss of ecological function;

d.

The proposed buffer width is not less than 75 percent of the standard buffer width at any point; and

e.

The proposed buffer reduction is not proposed in conjunction with buffer averaging.

6.

Piped watercourse setbacks.

a.

The intent of applying setbacks to piped watercourses is to preserve the opportunity to daylight watercourses that were previously piped, to provide incentives to property owners to daylight and enhance previously piped watercourses, and to allow flexibility for development where daylighting piped watercourses is demonstrated to be infeasible.

b.

Setbacks shall be established 45 feet from the centerline of piped watercourses.

c.

Piped watercourses setback widths shall be reduced to a 15-foot buffer when the portion of the piped watercourse on the applicant's property is daylighted and where the watercourse has been restored to an open channel, provided a restoration plan demonstrates:

i.

The watercourse channel will be stable and is not expected to cause safety risks or environmental damage; and

ii.

No additional impact nor encumbrance by watercourse buffer or critical area setback is added to properties neighboring the applicant(s) property.

d.

Piped watercourse setback widths shall be reduced to: (i) ten feet on lots with a lot width of 50 feet or more, and (ii) five feet on lots with a width of less than 50 feet, when daylighting is determined by qualified professional(s) to result in one or more of the following outcomes:

i.

Increased risk of landslide or other potential hazard that cannot be mitigated;

ii.

Increased risk of environmental damage (e.g., erosion, diminished water quality) that cannot be mitigated;

iii.

The inability of a legally established existing lot to meet the vehicular access requirements of this title; or

iv.

The inability of a legally established existing lot to meet the building pad standards in section 19.09.090.

7.

Buildings and other structures shall be set back a minimum of ten feet from the edges of a watercourse buffer. The distance may be reduced to five feet if:

a.

The watercourse is Type Ns;

b.

The buffer does not contain habitat for WDFW priority species;

c.

A split-rail fence is installed along the perimeter of the buffer; and

d.

Survey markers are installed along the perimeter of the buffer to establish its field location.

Figure 2: Example of Critical Area Setback

8.

The following may be allowed in the critical area setback, provided no structures nor building overhangs may be closer than five feet from the edge of a watercourse buffer:

a.

Landscaping;

b.

Uncovered decks less than 30 inches above existing or finished grade, whichever is lower;

c.

Building overhangs if such overhangs do not extend more than 18 inches into the setback area;

d.

Hardscape and driveways; provided, that such improvements may be subject to requirements in chapter 15.09, storm water master program;

e.

Split-rail fences;

f.

Trails, consistent with the requirements of this chapter; and

g.

Subgrade components of foundations; provided, that any temporary impacts to building setbacks shall be restored to their previous condition or better.

D.

Development standards—Additional criteria for specific activities.

1.

New watercourse crossings, such as bridges and culverts, may be permitted provided the standards in WAC 220-660-190 have been demonstrated to be met.

2.

The construction of trails within watercourse buffers is allowed, subject to the following:

a.

Trail surfaces shall be constructed of pervious materials and may not be wider than five feet;

b.

Trails shall be located to minimize the need for tree removal; and

c.

Trails shall be located only in the outer 25 percent of the buffer area.

3.

The trail width shall be added to the buffer width applied to the watercourse (e.g., if a trail is three feet wide, the watercourse buffer for the portion of the watercourse where the trail is located shall be expanded by three feet); except that the trail width shall not be added to the buffer width when trails are being created for public access and contained within a public access easement or right-of-way.

E.

Mitigation requirements. Mitigation measures shall achieve equivalent or greater ecological function including, but not limited to:

1.

Habitat complexity, connectivity, and other biological functions;

2.

Seasonal hydrological dynamics, water storage capacity and water quality; and

3.

Geomorphic and habitat processes and functions.

(Ord. 19C-05 § 1 (Exh. A))

A.

Designation and typing. Wetlands shall be identified and their boundaries delineated in accordance with the approved federal delineation manual and applicable regional supplements described in WAC 173-22-035. Wetlands shall be rated according to the Washington State Rating System for Western Washington: 2014 Update (Hruby, 2014), or most current update.

B.

General review requirements.

1.

In addition to the critical area study requirements listed in section 19.07.110, critical area study, critical area studies on wetlands shall also include:

a.

Wetland rating forms and datasheets;

b.

Discussion of landscape setting;

c.

A functional analysis of the project demonstrating that there will be no loss of ecological function; and

d.

A mitigation plan.

2.

Wetland delineations are valid for five years.

3.

Wetlands must be delineated and rated by a qualified professional.

C.

Development standards—Buffers.

1.

The following minimum buffers shall be established from the wetland boundary:

2.

Where a legally established and constructed street transects a wetland buffer, the department may approve a modification of the standard buffer width to the edge of the street if the isolated part of the buffer does not provide additional protection of the wetland and provides insignificant biological, geological or hydrological buffer functions relating to the wetland.

3.

Prohibited activities. The following uses are prohibited within any wetland or associated buffer: removal, excavation, grading, or dredging of material; draining flooding or disturbing the wetland, water level or water table; construction, reconstruction, demolition, or expansion of any structure.

4.

Neither lot coverage nor hardscape shall be permitted within a wetland or wetland buffer except as specifically provided in this chapter.

5.

Buffer averaging. Buffer width averaging shall be allowed provided the following requirements are met:

a.

The applicant has demonstrated how impacts have been avoided consistent with section 19.07.100, mitigation sequencing;

b.

The applicant has demonstrated how all proposed impacts have been mitigated consistent with subsection E of this section and will not result in a loss of ecological function;

c.

The proposed buffer width is not less than 75 percent of the standard buffer width at any point; and

d.

The total area of the buffer is equal to the area required without averaging.

6.

Buffer reduction. Buffer width reduction shall be allowed provided the following requirements are met:

a.

The applicant has demonstrated that buffer averaging would not feasibly allow development;

b.

The applicant has demonstrated how impacts will be minimized and that avoidance has been addressed consistent with section 19.07.100, mitigation sequencing;

c.

The applicant has demonstrated how all proposed impacts have been mitigated consistent with subsection E of this section and will not result in a loss of ecological function;

d.

The proposed buffer width is not less than 75 percent of the standard buffer width at any point; and

e.

The proposed buffer reduction is not proposed in conjunction with buffer averaging.

7.

Buildings and other structures shall be set back a minimum of ten feet from the edges of a wetland buffer. The distance may be reduced to five feet if:

a.

The wetland is:

i.

Hydrologically isolated;

ii.

Category III or IV;

iii.

Less than 1,000 square feet;

iv.

In an area that is not associated with riparian areas or buffers;

v.

Not part of a wetland mosaic; and

vi.

Does not contain habitat for WDFW priority species;

b.

A split-rail fence is installed along the perimeter of the buffer; and

c.

Survey markers are installed along the perimeter of the buffer to establish its field location.

8.

The following may be allowed in the critical area setback, provided no structures nor building overhangs may be closer than five feet from the edge of a wetland buffer:

a.

Landscaping;

b.

Uncovered decks less than 30 inches above existing or finished grade, whichever is lower;

c.

Building overhangs if such overhangs do not extend more than 18 inches into the setback area;

d.

Hardscape and driveways; provided, that such improvements may be subject to requirements in chapter 15.09, storm water management program;

e.

Split-rail fences;

f.

Trails, consistent with the requirements of this chapter; and

g.

Subgrade components of foundations; provided, that any temporary impacts to building setbacks shall be restored to their previous condition or better.

D.

Development standards—additional criteria for specific activities.

1.

Alterations to wetlands are allowed when the applicant has demonstrated how mitigation sequencing has been applied pursuant to section 19.07.100, mitigation sequencing, and when the applicant has demonstrated that the wetland is:

a.

All isolated Category IV wetlands less than 4,000 square feet that:

i.

Are not associated with riparian areas or their buffers;

ii.

Are not associated with shorelines of the state or their associated buffers;

iii.

Are not part of a wetland mosaic;

iv.

Do not score five or more points for habitat function based on the 2014 update to the Washington State Wetland Rating System for Western Washington: 2014 Update (Ecology Publication No. 14-06-029, or as revised and approved by Ecology);

v.

Do not contain a priority habitat or a priority area for a priority species identified by the Washington Department of Fish and Wildlife, do not contain federally listed species or their critical habitat, or species of local importance identified in section 19.07.170.

b.

Wetlands less than 1,000 square feet that meet the above criteria and do not contain federally listed species or their critical habitat are exempt from the buffer provisions contained in this chapter.

2.

The construction of trails within wetland buffers is allowed subject to the following requirements:

a.

Trail surfaces shall be constructed of pervious materials and may not be wider than five feet;

b.

Trails shall be located to minimize the need for tree removal; and

c.

Trails shall be located only in the outer 25 percent of the buffer area.

d.

The trail width shall be added to the buffer width applied to the wetland (e.g., if a trail is three feet wide, the wetland buffer for the portion of the wetland where the trail is located shall be expanded by three feet); except that the trail width shall not be added to the buffer width when trails are being created for public access and contained within a public access easement or right-of-way.

3.

Development proposals shall incorporate the following measures unless the applicant can demonstrate that they would result in no net environmental benefit or that they are not applicable:

E.

Mitigation requirements. When mitigation for wetland and/or wetland buffer impacts is required, mitigation shall meet the requirements listed below:

1.

Compensatory mitigation for alterations to wetlands shall be used only for impacts that cannot be avoided or minimized and shall achieve equivalent or greater biologic functions compared to predevelopment conditions. Compensatory mitigation plans shall be consistent with Wetland Mitigation in Washington State — Part 2: Developing Mitigation Plans — Version 1, (Ecology Publication No. 06-06-011b, Olympia, WA, March 2006, as revised), and Selecting Wetland Mitigation Sites Using a Watershed Approach (Western Washington) (Publication No. 09-06-32, Olympia, WA, December 2009, as revised).

2.

Mitigation for alterations to wetland(s) and/or wetland buffer(s) shall achieve equivalent or greater ecological function.

3.

No net loss. Wetland mitigation actions shall not result in a net loss of wetland area.

4.

Mitigation actions shall be in-kind and conducted within the same sub-basin and on the same site as the alteration except when the following apply:

a.

There are no reasonable on-site opportunities for mitigation or on-site opportunities do not have a high likelihood of success due to adjacent land uses;

b.

On-site buffers or connectivity is inadequate;

c.

Off-site mitigation has a greater likelihood of providing equal or improved wetland functions than the impacted wetland; and

d.

Off-site locations have been identified and evaluated in the following order of preference:

i.

Within the same drainage sub-basin;

ii.

Within the city limits;

iii.

Within the Mercer Island service area for an approved mitigation bank program site within the WRIA 8 in accordance with the requirements in subsection (E)(6) of this section.

e.

Where feasible, off-site mitigation projects shall be completed prior to activities that will disturb wetlands. In all other cases, mitigation shall be completed immediately following site disturbance and prior to use or occupancy of the activity or development. Construction of mitigation projects shall be timed to reduce impacts to existing wildlife and flora.

5.

Mitigation ratios.

a.

The following ratios shall apply to required wetland mitigation. The first number specifies the acreage of replacement wetlands and the second specifies the acreage of wetlands altered.

b.

Permanent wetland mitigation. The following ratios of area of mitigation to area of alteration apply to mitigation measures for permanent alterations:

c.

Temporary wetland mitigation. The following ratios of area of mitigation to area of alteration apply to mitigation measures for temporary alterations where wetlands will not be impacted by permanent fill material:

d.

Wetland buffer replacement ratio. Altered wetland buffer area shall be replaced at a minimum ratio of one-to-one; provided, that the replacement ratio may be increased if needed to replace lost functions and values.

e.

Increased mitigation ratio. The code official may increase the ratios under the following circumstances:

i.

Uncertainty exists as to the probable success of the proposed restoration or creation; or

ii.

A significant period of time will elapse between impact and replication of wetland functions; or

iii.

Proposed mitigation will result in a lower category wetland or reduced functions relative to the wetland being impacted; or

iv.

The impact was an unauthorized impact.

f.

Decreased mitigation ratio. The code official may decrease these ratios under the following circumstances:

i.

Documentation by a qualified professional demonstrates that the proposed mitigation actions have a very high likelihood of success. This documentation should specifically identify how the proposed mitigation actions are similar to other known mitigation projects with similar site-specific conditions and circumstances that have been shown to be successful; or

ii.

Documentation by a qualified professional demonstrates that the proposed mitigation actions will provide functions and values that are significantly greater than the wetland being impacted; or

iii.

The proposed mitigation actions are conducted in advance of the impact and have been shown to be successful over the course of at least one full year.

6.

Wetland banking.

a.

Credits from a wetland mitigation bank may be approved for use as compensation for unavoidable impacts to wetlands when:

i.

The criteria in subsection (E)(4) of this section are demonstrated to have been met;

ii.

The bank is certified under WAC Chapter 173-700;

iii.

A qualified professional has demonstrated that the wetland mitigation bank provides appropriate compensation for the authorized impacts;

iv.

The proposed use of credits is consistent with the terms and conditions of the bank's certification; and

v.

The compensatory mitigation agreement occurs in advance of authorized impacts.

b.

Replacement ratios for projects using bank credits shall be consistent with replacement ratios specified in the bank's certification.

c.

Credits from a certified wetland mitigation bank may be used to compensate for impacts located within the service area specified in the bank's certification. In some cases, bank service areas may include portions of more than one adjacent drainage basin for specific wetland functions.

7.

Preference of mitigation actions. Compensatory wetland mitigation shall occur in the following order of preference:

a.

Restoration;

b.

Creation;

c.

Enhancement;

d.

Preservation.

8.

Site protection. As a condition of any permit or land use approval, the code official may require permanent fencing and signage to be installed around the wetland or buffer. Fencing installed as part of a proposed activity or as required in this subsection shall be designed to not interfere with species migration, including fish runs, and shall be constructed in a manner that minimizes impacts to the wetland and associated habitat.

(Ord. 19C-05 § 1 (Exh. A))