18.08.170 Wetlands – Replacement criteria

18.08.170 Wetlands – Replacement criteria.

A. Where wetlands are altered, the applicant shall meet the minimum requirements of this section.

B. When it is proposed to alter or eliminate a wetland and the department is considering the alteration or elimination, the applicant shall be required to replace or enhance the functions and values of the affected wetland. The wetland values will be based on an approved evaluation procedure. The recommended ratios for replacement/compensation are as established in the following table:

Wetland Type	Replacement Ratio
Category I	6 to 1 (for unauthorized wetland impact only)
Category II	3 to 1
Category III	2 to 1
Category IV	1.5 to 1

C. Ratios provided are for proposed projects with on-site, in-kind replacement which occurs prior to development of the site. Replacement ratio for unauthorized wetland impact requires replacement at a ratio two times that listed for the wetland categorical type. The increased ratio is based on the uncertainty of probable success of proposed replacement, projected losses of wetland functions and values, or significant period of time between elimination and replacement of wetland. Such required increases in replacement ratios will be made by the department after review of all pertinent data relating to the proposed or committed alteration.

D. The department will allow the ratios to be decreased if the applicant provides findings of special studies coordinated with agencies with expertise which demonstrate to the satisfaction of the department that no net loss of wetland function or value is attained under the decreased ratio.

E. The replacement ratio may be decreased to a ratio of 1:1, if the following criteria are met:

1. The applicant shows to the satisfaction of the department that a replacement ratio of greater than 1:1 is either not feasible on-site, would be likely to result in substantial degradation of other natural features or results in an increase of wetland function and values; and

2. The applicant submits to the department a wetland mitigation plan according to the requirements of GHMC 18.08.150 and 18.08.160 which shows to the satisfaction of the department that a net increase in wetland functions and values will result from the mitigation; and

3. The mitigation is completed and monitored by the department for one year after completion of the mitigation. After one year the department shall make a determination of whether or not the mitigation has been successful.

a. If the department is satisfied that the mitigation will successfully meet the anticipated final outcome of the wetland mitigation plan, development permits may be issued and development activity on the site may begin.

b. If the department is not satisfied that the mitigation will successfully meet the anticipated final outcome of the wetland mitigation plan, development permits shall not be issued and development activity on the site shall not begin. Modifications to the wetland mitigation plan and further monitoring may be required until the department is satisfied that the mitigation will be successful.

F. In-kind compensation shall be provided except where the applicant can demonstrate to the satisfaction of the department that:

1. The wetland system is already significantly degraded and out-of-kind replacement will result in a wetland with greater functional value; or

2. Scientific problems such as exotic vegetation and changes in watershed hydrology make implementation of in-kind compensation impossible; or

3. Out-of-kind replacement will best meet identified regional goals (e.g., replacement of historically diminished wetland types); or

4. Where out-of-kind replacement is accepted, greater acreage replacement ratios may be required to compensate for lost functions and values.

G. Site-specific quantifiable criteria shall be provided for evaluating whether or not the goals and objectives for the proposed compensation are being met. Such criteria include but are not limited to water quality standards, survival rates for planted vegetation, habitat diversity indices, species abundance or use patterns, hydrological standards including depths and durations of water patterns. Detailed performance standards for mitigation planning shall include the following criteria:

1. Use only plants indigenous to Pierce County (not introduced or foreign species);

2. Use plants appropriate to the depth of water at which they will be planted;

3. Use plants available from local sources;

4. Use plant species high in food and cover value for fish and wildlife;

5. Plant mostly perennial species;

6. Avoid committing significant areas of site to species that have questionable potential for successful establishment;

7. Plant selection must be approved by a qualified wetland specialist;

8. Water depth is not to exceed six and one-half feet (two meters);

9. The grade or slope that water flows through the wetland is not to exceed six percent;

10. Slopes within the wetland basin and the buffer zone should not be steeper than 3:1 (horizontal to vertical);

11. The substrate should consist of a minimum of one foot, in depth, of clean (uncontaminated with chemicals, or solid/hazardous wastes) inorganic/organic materials;

12. Planting densities and placement of plants shall be determined by a qualified wetland specialist and shown on the design plans;

13. The wetland (excluding the buffer area) should not contain more than 60 percent open water as measured at the seasonal high water mark;

14. The planting plan must be approved by a qualified wetland specialist;

15. Stockpiling shall be confined to upland areas and contract specifications should limit stockpile durations to less than four weeks;

16. Planting instructions shall describe proper placement, diversity, and spacing of seeds, tubers, bulbs, rhizomes, sprigs, plugs, and transplanted stock;

17. Apply controlled release fertilizer at the time of planting and afterward only as plant conditions warrant (determined during the monitoring process), and only to the extent that the release would be conducted in an environmentally sound manner;

18. Install an irrigation system, if necessary, for initial establishment period;

19. Construction specifications and methods shall be approved by a qualified wetland specialist and the department;

20. All mitigation shall be consistent with requirements of Chapter 15.04 GHMC and city storm drainage comprehensive plan;

21. As appropriate, and if impacts to natural wetland functions and values can be fully mitigated, capacity of the wetland to store surface water should be equal to or greater than surface water storage capacity prior to the proposed activity;

22. As appropriate, and if impacts to natural wetland functions and values can be fully mitigated, ability of the wetland to intercept surface water runoff on the site should be equal to or greater than such ability prior to the proposed activity;

23. As appropriate, and if impacts to natural wetland functions and values can be fully mitigated, the ability of the wetland to perform stormwater detention functions should be equal to or greater than such functions prior to the proposed activity.

H. Wetland mitigation shall occur according to the approved wetland mitigation plan, and shall be consistent with all provisions of this regulation.

I. On completion of construction required to mitigate for impacts to wetlands, the wetland mitigation project shall be signed off by an approved qualified wetland specialist and the city’s environmental official. Signature will indicate that the construction has been completed as planned. (Ord. 1036 § 24, 2006; Ord. 726 § 6, 1996; Ord. 611 § 1, 1991).