§ 24.35.380. Wetlands—Special reports—Wetland mitigation plan.

Wetland impacts shall be mitigated consistent with an approved mitigation plan. The applicant shall submit a conceptual wetland mitigation plan generally containing the information listed below, as applicable. The county may require use of a standardized wetland mitigation report format.

If the approval authority approves the conceptual mitigation plan, the applicant shall submit a detailed mitigation plan to the approval authority for review and approval, consistent with the provisions of this section. Prior to submitting detailed wetland mitigation plan, the applicant shall meet with the approval authority to discuss the submittal requirements.

A.

Demonstrate Qualifications. A professional wetland scientist shall prepare the mitigation plan. This scientist shall be knowledgeable of wetland conditions within Thurston County and have experience designing wetland mitigation projects, at least some of which have been installed and monitored for a minimum of two years. The design team may include other participants as needed.

Applicants proposing a wetland mitigation project shall demonstrate that the individuals designing, constructing, and monitoring the project have sufficient expertise, supervisory capability, and financial resources to carry out the proposed project. A project manager shall be named, and the qualifications of each team member involved in preparing the mitigation plan and implementing and supervising the project shall be provided, including educational background, areas of expertise, training, and experience with comparable projects. The approval authority, in consultation with Ecology, shall verify the success of the mitigation

B.

Report. Wetland mitigation plans shall include a written report and a site plan, commensurate with the scope of the development proposal, including the relevant components listed below (also see the Draft Guidance on Wetlands Mitigation in Washington State, Washington State Department of Ecology publication number 04-06-013B Part 2, 2004):

1.

The applicant's name and contact information;

2.

The name, qualifications, and contact information for the primary report author(s);

3.

The location and parcel number of proposed mitigation area;

4.

Identification of all the local, state, and federal wetland related permits required for the project;

5.

A description of the impacted wetland including, at a minimum:

a.

The wetland's landscape position and the geomorphology of the impacted site;

b.

The wetland's category, consistent with TCC 24.30.030;

c.

The wetland's hydrogeomorphic class;

d.

A characterization of existing wetland and buffer functions;

e.

Existing wetland acreage;

f.

Vegetative communities, affected Cowardin classes;

g.

Hydrologic characteristics;

h.

Soil and substrate conditions; and

i.

Topography.

6.

A description of the compensation site, if different from the impacted wetland site, including at a minimum:

a.

Site size;

b.

Plant communities/Cowardin classes present on site, including any invasive plants or noxious weeds;

c.

Existing wetland and buffer functions;

d.

Soil and substrate conditions; and soils (e.g., soil pit data - hand dug or mechanically trenched, soil boring data; not soil survey data);

e.

Topography;

f.

General hydrologic patterns on the site including identification of groundwater availability; frequency, depth, duration, and timing of flooding; the field data collected to document existing conditions on which future condition assumptions will be based for the hydroperiod; the site's relationship to the watershed/water bodies and demonstration that the site will have an hydrogeomorphic class appropriate for its position in the landscape. Hydrologic monitoring and analysis may be required to document that the proposed source of water and predicted hydroperiod are attainable and suitable for the site and will not adversely impact an existing wetland. If the proposed project could affect Category I wetlands, the approval authority may require computer modeling in determining the hydroperiod;

g.

For those sites that have been recently altered or degraded, a description of historic conditions;

h.

The adjacent site conditions and any known proposed use;

7.

An estimate of future conditions at the proposed compensation site if the compensation actions are not undertaken (i.e., how would this site progress through natural succession);

8.

A summary of the proposed wetland and buffer impacts and the proposed compensation concept, including:

a.

Site selection criteria;

b.

Demonstration that the proposed mitigation replaces all lost and diminished wetland and buffer functions;

c.

A complete description of the structure and functional relationships sought in the new wetland and buffer;

d.

For years 1, 3, 5, 10 and 25, and post-installation, conditions expected from the proposed actions on the compensation site including future hydrogeomorphic types, vegetation community types by dominant species (wetland and upland), and including the succession of vegetation community types and dominants expected;

e.

An assessment of the potential changes in wetland hydroperiod due to the proposed project and how the design has been modified to avoid, minimize or reduce adverse impacts to the wetland hydroperiod;

f.

The successional sequence of expected changes in hydroperiod for the compensation site(s) for years 1, 3, 5, 10, 25 and post installation;

g.

The change in habitat characteristics expected over the same twenty-five-year time period;

h.

An analysis of the likelihood of persistence of the created or restored wetland based on such factors as surface and groundwater supply and flow patterns, dynamics of the wetland ecosystem, sediment or pollutant influx and/or erosion, periodic flooding and drought, presence of invasive flora or fauna, and potential human or animal disturbance.

9.

Identification of the mitigation goals, objectives, and the performance standards that will be used to evaluate whether the mitigation is achieving the project goals and objectives.

Identification of the reference wetland used to develop the project goals, objectives and performance standards.

The performance standards shall provide a measurable benchmark for determining whether the project is meeting the mitigation goals and objectives at various stages in the project and establish thresholds for triggering remedial action or contingency measures. At a minimum, performance standards shall address the following:

a.

Wetland size;

b.

The water regime, (e.g., establishment of wetland hydrology, permanently ponded, seasonally inundated); designed hydroperiods; and water quality. Including identification of the proposed method by which the hydroperiod will be evaluated;

c.

Vegetative structure and establishment of viable plant communities (e.g., percent cover with wetland species, area of various Cowardin classes, multi-species, mixed canopy community comprised of emergent, scrub-shrub, and tree species); and survival rates of planted vegetation and coverage for each vegetative stratum;

d.

Hydric soil formation;

e.

If relevant, wildlife habitat (species abundance and diversity targets, habitat diversity indices), or other ecological, geological or hydrological factors;

10.

The dates for beginning and completing the project;

11.

For wetland restoration and creation projects, a review of the available literature and/or experience to date in restoring or creating the type of wetland proposed;

12.

Maintenance plan. A maintenance plan shall be submitted that describes proposed management practices that will protect the wetland and buffer after the project site has been developed. Maintenance includes, but is not limited to, the removal and control of invasive vegetation and noxious weeds, replacement of dead or dying planted vegetation and trash and debris removal;

13.

Monitoring and contingency plans. Monitoring and contingency plans shall be submitted consistent with TCC 24.35.017.

C.

Construction Plans. If the detailed mitigation plan is approved, the applicant shall submit construction plans consistent with the approved mitigation plan, and a sequence of construction activities. Wetland mitigation shall occur consistent with a schedule approved by the approval authority.

Written specifications and descriptions of compensation techniques shall be provided including, but not limited to, the proposed construction sequence, grading and excavation details, erosion and sediment control features needed for wetland construction and long-term survival, a planting plan specifying plant species, quantities, locations, size, spacing, and density; source of plant materials, propagules, or seeds; water and nutrient requirements for planting; where appropriate, measures to protect plants from predation; irrigation requirements; specification of substrate stockpiling techniques and planting instructions; descriptions of water control structures and water-level maintenance practices needed to achieve the necessary hydrocycle/hydroperiod characteristics;

These written specifications shall be accompanied by detailed site diagrams, scaled cross-sectional drawings, and topographic maps showing slope percentage and final grade elevations, and any other drawings appropriate to show construction techniques or the anticipated final outcome. The plan shall provide for elevations which are appropriate for the desired habitat type(s) and which provide sufficient tidal prism and circulation data. The scaled plan sheets for the compensatory mitigation must contain, at a minimum:

1.

Existing wetland and buffer boundaries, proposed areas of wetland and/or buffer impacts, location of proposed wetland and/or buffer compensation actions;

2.

Approximated site topography before and after alteration at one-foot contour intervals in the zone of the proposed compensation actions if any grading activity is proposed to create the compensation area(s).

3.

A planting plan prepared by a wetland specialist including plant selection, planting densities, placement, planting instructions, water and nutrient requirements, and provision for an irrigation system, if necessary, until plants are established.

D.

Construction Monitoring. The wetland scientist who designed the mitigation project shall be on-site to provide construction oversight as warranted to ensure that the project is constructed as designed.

E.

As-built. Upon completion of construction for the wetland mitigation project, the applicant shall submit an as-built report to the county for review and approval.

F.

Budget. A detailed budget for implementing the mitigation plans, including construction, monitoring, maintenance, and contingency phases shall be submitted.

G.

Surety. A surety estimate for the entire compensatory mitigation including the following elements: site preparation, plant materials, construction materials, installation oversight, maintenance twice/year for up to five years, annual monitoring field work and reporting, and contingency actions for a maximum of the total required number of years for monitoring. Separate estimates shall be prepared for the installation phase and monitoring and maintenance phase of the project; a surety consistent with Chapter 24.70 TCC is required for the duration of the monitoring period.

(Ord. No. 14773, § 3(Att. B), 7-24-2012)