§ 25.09.065. Mitigation standards

A.

Regulations set out in this Chapter 25.09 are minimum requirements that shall be supplemented by mitigation sequencing in this Section 25.09.065 when needed to protect the ecological functions of steep slope erosion hazard areas and their buffers, wetlands, wetland buffers, fish and wildlife habitat conservation areas, and flood prone areas.

B.

Mitigation sequencing

1.

Mitigation below shall be undertaken in the following priority:

a.

Avoiding the impact altogether by not taking a certain action or parts of an action;

b.

Minimizing impacts by limiting the degree or magnitude of the action and its implementation by using appropriate technology, best management practices, and/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;

e.

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

f.

Monitoring the impact and the compensation projects undertaken under subsection 25.09.065.B.1.e and taking appropriate corrective measures.

2.

Priority requirements. Lower priority measures shall be applied only if the higher priority measure is infeasible or inapplicable.

3.

Priority for the location of ecological mitigation in relation to compensation required under subsection 25.09.065.B.1.e shall be in the following order and the lower priority restoration location shall be allowed only if the higher priority location is infeasible or the applicant demonstrates that there will be a greater ecological benefit if a lower priority site is used:

a.

At the site;

b.

Within the same creek watershed;

c.

Within Seattle city limits;

d.

Within the same Watershed Resource Inventory Area.

4.

If the required mitigation undertaken under subsection 25.09.065.B.1.e is infeasible, the applicant shall apply for an exception pursuant to Section 25.09.300 to allow the development.

5.

As part of any application for approval of development that requires mitigation, the applicant shall submit a mitigation plan that meets the standards of subsection 25.09.065.C and a maintenance and monitoring plan that meets the standards of subsection 25.09.065.D unless the applicant demonstrates based on competent scientific evidence that no impact to the ecological functions of the environmentally critical area or areas will occur as the result of the development or its use, construction, or management. The mitigation plan and the maintenance and monitoring plan must be approved by the Director.

6.

Mitigation timing. Mitigation shall be completed prior to issuance of the certificate of occupancy. If that has not occurred or if no certificate of occupancy is needed, the applicant shall submit plans establishing a specific schedule for completing mitigation, which must be approved by the Director, and shall provide a bond of at least 150 percent of the cost of installation, in addition to the monitoring plan and bond required under subsection 25.09.065.D if the mitigation exceeds $5,000. No additional bond is required for public agencies.

C.

Mitigation plan

1.

Mitigation plans for tree and vegetation management, and impervious surface management shall include the information required in subsections 25.09.070.G, including and not limited to native plant species, planting location, demonstration of replacement of ecological function, and timing of vegetation removal.

2.

Mitigation for other impacts

a.

The Director shall determine the level of detail required in the mitigation plan after considering the location, size, and type of the proposed development and/or the use and type of mitigation proposed, unless a specific timeframe is stated.

b.

The mitigation plan shall include the following information:

1)

An inventory of the existing ecological functions where the impact will occur;

2)

An analysis of the project's impacts on the existing ecological functions necessary to support existing environmentally critical areas and buffers;

3)

Management recommendations or requirements received from federal, state, or local agencies that have been developed for to protect the ecological functions of environmentally critical areas including protection of avian, terrestrial, wetlands, or aquatic species and habitat on the site and their applicability to the proposal;

4)

Proposed management practices to protect the ecological functions of environmentally critical areas both during construction and during the management of the site;

5)

Measures to avoid and minimize impacts to preserve existing habitats and the ecological functions of environmentally critical areas and buffers;

6)

Proposed measures to compensate for the remaining project impacts after applying avoidance and minimization measures, to ensure protection of the ecological functions of environmentally critical areas; and

7)

Any additional information that the Director requires to determine the impacts of a proposal and required mitigation to offset the impacts.

D.

Maintenance and monitoring plan

1.

Maintenance and monitoring plans shall include:

a.

Criteria for determining the success of mitigation and for evaluating the effectiveness of mitigation to ensure protection of the ecological functions of the environmentally critical areas;

b.

Contingency actions to be taken if the mitigation fails to meet the established success criteria in subsection 25.09.065.D.1.a; contingency actions shall include additional monitoring if the mitigation fails;

c.

Performance bonds for wetlands, wetland buffers, fish and wildlife habitat conservation areas, and flood prone areas not to exceed a term of five years are required to ensure compliance with the conditions for mitigation if the cost of the mitigation is greater than $5,000, except for public agencies. The bond shall be in an amount of at least 150 percent of the cost to retain a qualified environmental professional in the appropriate field to assess the mitigation and submit a report to the City at least twice yearly, prior to and near the end of each growing season and shall also provide a bond in an amount sufficient to implement additional restoration measures if the mitigation does not meet the success criteria identified in subsection 25.09.065.D.1.a at the end of five growing seasons; and

d.

Any additional information that the Director requires to help ensure the success of the mitigation.

2.

Mitigation that includes planting trees and vegetation shall include:

a.

Tree and vegetation species, planting location, and soil amendment criteria meeting the standards in subsection 25.09.070.G.2;

b.

Not less than five years of maintenance that ensures 80 percent survival of new trees and vegetation planted at the end of five years;

c.

Annual inspections of the plants;

d.

Replacement of failed plants;

e.

Removal of exotic invasive species that have become established; and

f.

Photographic documentation of planting success retained for the five year period.

E.

Additional requirements for steep slope erosion hazard areas. The Director shall require mitigation of all impacts to the natural erosion capacity of the disturbed steep slope erosion hazard area in the following order of preference:

1.

Removing ivy on site in the remaining steep slope erosion hazard areas and their buffers.

2.

Removing other invasive vegetation and planting native trees and vegetation in the remaining steep slope erosion hazard areas and their buffers.

3.

Removing ivy on adjacent parcels.

4.

Removing other invasive vegetation and planting native trees and vegetation on site in areas outside the steep slope erosion hazard areas and their buffers.

F.

Additional requirements for wetland and wetland buffers

1.

Mitigation for grading, filling, or draining wetlands shall achieve the equivalent or better biologic functions of the existing wetland, except as provided in this subsection 25.09.065.F.1. Mitigation plans shall be consistent with Washington State Department of Ecology Publication #06-06-011b, Wetland Mitigation in Washington State - Part 2: Developing Mitigation Plans (Version 1), or the most current Department of Ecology publication addressing wetland mitigation.

2.

Mitigation actions that require compensation by replacing, enhancing, or substitution shall occur in the following order of preference:

a.

Restoring wetlands on sites that were formerly wetlands.

b.

Creating wetlands on disturbed sites, such as those with vegetative cover consisting primarily of exotic introduced species.

c.

Enhancing wetlands and/or wetland buffers with significantly degraded functions and values. The amount of required enhancement is dependent on the wetland classification in subsection 25.09.065.F.3.

3.

Wetland restoration, creation, and enhancement ratios

a.

The ratios set out in Table A for 25.09.065 are required for the restoration, creation, or enhancement of wetlands for authorized alterations, except as provided in subsections 25.09.065.F.3.b, 25.09.065.F.3.c, and 25.09.065.F.3.

Table A for 25.09.065 Wetland restoration, creation, rehabilitation and enhancement ratios Note: The first number specifies the area of replacement, creation rehabilitation or enhancement of wetlands, and the second number specifies the area of wetlands altered.
	Restoration or creation ratios	Rehabilitation	Enhancement ratios
Category I: Bog, Natural heritage site	Not considered possible	Case by case	Case by case
Category I: Mature Forested	6:1	12:1	24:1
Category I: Based on Function	4:1	8:1	16:1
Category II	3:1	6:1	12:1
Category III	2:1	4:1	8:1
Category IV	1.5:1	3:1	6:1

 

b.

Restoration, creation, and enhancement ratios may be increased under the following circumstances to achieve the equivalent wetland function of the wetland that is altered:

1)

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

2)

A significant period of time will elapse between impact and establishment of wetland functions at the mitigation site; or

3)

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

c.

Restoration, creation, and enhancement ratios may be decreased when the proposed mitigation actions are conducted in advance of the impact and result in no net loss in wetland functions.

4.

Except for wetlands where no net loss of wetlands is a federal requirement, if the applicant demonstrates by clear and convincing evidence that the avoidance and mitigation standards required in subsections 25.09.065.B and 25.09.065.F will deprive the applicant of reasonable use of the applicant's property, the Director may waive or modify the standards in subsection 25.09.065.F to the extent necessary to allow reasonable use as part of the exception under Section 25.09.300. Notwithstanding such demonstration, the Director may deny the waiver if the Director determines that not applying these standards would cause significant injury to occupiers of the land, to other properties, to public resources, or to the environment.

5.

Other agency regulations. Review of projects subject to the wetland provisions of this Chapter 25.09 shall be coordinated by the applicant with the appropriate state and federal agencies. The applicant should make early contact with these agencies to ensure compliance with local, state, and federal regulations.

(Ord. 125292 , § 1, 2017; Ord. 125248 , § 12, 2017.)