§ 418-13. Mitigation plan; requirements.

A. 

Mitigation measures.

(1) 

After it has been determined by the Planning Board pursuant to § 418-12D that losses of wetlands/watercourses or buffers are necessary and unavoidable and have been minimized to the maximum extent practicable, the applicant shall develop a mitigation plan which shall specify mitigation measures that provide for mitigation as follows:

(a) 

For losses to wetlands: replacement wetlands or enhancement or restoration of existing wetlands that re-create as nearly as possible the original wetlands in terms of type, functions and geographic location and setting and that are larger than, by a ratio of two to one (2:1), the original wetlands, provided that the ecological impacts associated with the mitigation are not greater than those associated with the proposed activity.

(b) 

For losses to watercourses: replacement, enhancement or restoration of the watercourse that re-creates as nearly as possible the disturbed or lost portion of the original watercourse in terms of type, function and geographic location and setting, by a ratio of one to one (1:1), for the disturbed or lost portion of the watercourse, or the preparation of other mitigation plans acceptable to the approving authority that serve to replace or enhance the functions of the watercourse affected by the proposed activity.

(c) 

For losses to wetland buffers: enhancement of existing wetland buffers or enhancement or restoration of existing wetlands, by a ratio of two to one (2:1), for the area disturbed by the proposed activity that replaces or enhances the functions of the wetland or wetland buffer.

(2) 

For the purposes of mitigation, losses of wetland/watercourse buffers will be viewed as losses of wetlands. On-site mitigation shall be the preferred approach; off-site mitigation shall be permitted only in cases where an on-site alternative is not possible.

B. 

Mitigation plans developed to compensate for the loss of wetlands or wetland buffers shall include the following baseline data:

(1) 

Hydrologic data.

(a) 

Small projects (losses of two acres): land use history, macrotopography, general surficial geology and stream-flow measurements, groundwater levels and groundwater quality.

(b) 

Moderate projects (losses of two to 10 acres): data required for small projects, plus microtopography, bedrock geology, surficial geology, stream-flow velocity measurements, if appropriate, soil pore water storage (organic soils) and direct precipitation measurements.

(c) 

Large projects (losses of 10 acres): data required for small and moderate projects, plus water balance analysis (one-year study), groundwater storage, groundwater flow rates and soil pore water level and flow (organic soils).

(2) 

Soils.

(a) 

Small projects: soil profile descriptions, general soil survey data, bulk density, porosity, hydraulic conductivity, pH, conductivity, cation exchange capacity, redox potential, total phosphorus, total nitrogen, nitrate nitrogen and organic carbon.

(b) 

Moderate projects: data required for small projects, plus fiber content (organic soils), phosphorous retention, pore water analysis (seasonally), alkalinity, exchangeable acidity, seedbank capacity and soil organisms.

(c) 

Large projects: data required for small and moderate projects, plus clay mineralogy, microbial assessment (seasonally), heavy metals content, pesticides residues, gas/toxin analysis (seasonally), peat features and soil temperature regime.

(3) 

Vegetation.

(a) 

Small projects: areal wetland extent and qualitative measurement of percent plant cover, plant species list, vegetation cover type, relative stem density, animal species list, slope, microtopography, plant vigor, surface water connections, habitat structure, vegetation/open water ratio and surrounding terrestrial cover type.

(b) 

Moderate projects: data for small projects, plus comprehensive animal species list, potential phosphorous uptake and potential nitrogen uptake.

(c) 

Large projects: data for small and moderate projects, plus quantitative measurement of stem density, evapotranspiration data and net primary productivity.

(4) 

A monitoring schedule for a specified period of time as agreed to by the Environmental Conservation Commission.

C. 

The Planning Board shall monitor or shall cause to have monitored projects according to the specifications set forth in the permit to determine whether the elements of the mitigation plan and permit conditions have been met and whether the wetland acreage created replaces the wetland acreage lost. To this end, the Planning Board may contract with an academic institution, an independent research group or other qualified professionals at the expense of the applicant or may use its own staff expertise. The requirements for monitoring shall be specified in the mitigation plan and shall include but not be limited to:

(1) 

The time period over which compliance monitoring shall occur.

(2) 

Field measurements to verify the size and location of the impacted wetland area and the restored/replacement wetland area.

(3) 

The date of completion of the restoration/replacement.

(4) 

Field verification of the vegetative, hydrologic and soils criteria as specified in the mitigation plan and permit.

D. 

Any mitigation plan prepared pursuant to this section and accepted by the Planning Board shall become part of the permit for the application.

Amended 8-20-1991 by L.L. No. 7-1991