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The following subsections set forth minimum acceptable practices to be followed in surface mining and reclamation operations.

(a) Soil Erosion Control.

(1) The removal of upland vegetation and overburden in advance of mining shall be kept to the minimum. All riparian woody vegetation and wetlands must be avoided to the maximum extent possible. Prior to disturbance, riparian vegetation or wetlands must be clearly identified by mapping. Riparian vegetation comprising a contiguous one-eighth acre complex or at least two inches diameter at breast height must be mitigated for adverse impacts. Impacts to other vegetation must be described and submitted to the Committee within the mining and reclamation plan. These impacts may require mitigation at the discretion of the Committee. Impacted areas, which must be mapped, consist of woody vegetation which have drip lines within 25 feet of excavation activities (excavation, stockpiling, parking, etc.), or wetlands that are filled, excavated, or drained. Impacts to woody vegetation shall not include existing haul roads, stockpiles, etc.

(2) Stockpiles of overburden and minerals shall be managed to minimize water and wind erosion. This may include but is not limited to covering stockpiles with netting, canvas, or other materials to prevent detachment and transport of loose material by water or wind.

(3) Erosion control facilities such as retarding basins, settling ponds, ditches, stream bank stabilization, and diking shall be constructed and maintained where necessary to control erosion.

(4) Grading and revegetation shall be designed both to prevent excessive erosion and to convey surface runoff to natural drainage devices or interior basins designed for water storage. Basins that will store water during periods of surface runoff shall be designed to prevent downward erosion of spillways when these basins have an outlet to lower ground.

(b) Water Quality and Watershed Control.

(1) A method of compliance with the U.S. Environmental Protection Agency, Tribal, and other applicable regulations and requirements is hereby incorporated into the review process under this chapter.

(2) Settling ponds or basins shall be constructed downslope from areas of potential erosion at operations where they are necessary to protect water quality and comply with Tribal water quality regulations, or where they will provide significant benefit to water quality. Settling ponds and basins shall not be constructed in such a manner as to impound a natural watercourse. Settling ponds or basins shall be located and constructed in such a manner that they will not be a hazard to downstream resources in the event of natural or anthropogenic events, such as an earthquake, flood, landslide, or fire.

(3) Temporary stream or watershed diversion shall be restored in final reclamation in a manner which will prevent undue erosion and water quality degradation.

(4) At sites where ground-water recharge is a significant consideration, operations shall be conducted to substantially prevent siltation of recharge areas.

(5) Infiltration of toxic substances into ground water basins shall be prevented where such basin may contribute to domestic or agricultural water supplies.

(c) Flood Control. Compliance with the applicable requirements of other agencies in addition to the Committee, including the Tribal Fisheries Department and federal flood control agencies, is required when operations occur in or near tributaries and other drainage channels.

(d) Protection of Fish and Wildlife Habitat. All reasonable measures shall be taken to protect the habitat of fish and wildlife, and to prevent alteration of tributary and river beds and tributary and river flows. The Committee and Fisheries Departments shall prescribe measures as deemed necessary to better protect such resources.

(e) Disposal of Mine Waste Rock and Overburden.

(1) Waste piles and piles of overburden shall not be allowed unless provisions for such were submitted and approved as part of the original proposal for mitigation. In any case, any such mitigation plans which allow for piling of overburden or waste rock shall be in strict conformance with the Yurok Tribe water quality control plan (Chapter 21.25 YTC) and all other provisions of this chapter, as well as any conditions imposed by the Committee. Any piles not properly provided for and approved in the original mitigation plan will be considered a violation of this chapter.

(2) Stable slopes at the angle of repose shall be permitted as a final slope, when a qualified professional has determined that subsequent slope failures will not deliver earth materials to a watercourse, would deliver less than 10 cubic yards to the receiving slope, and will not threaten life or property. Where seismic and/or water saturation can adversely alter slope stability a qualified professional shall determine final slope requirements.

(3) Old equipment and other similar inert mining wastes shall be removed. These types of materials shall not be buried.

(4) Toxic material shall be removed and shall be protected to prevent leaching until it is removed.

(f) Soil Salvage.

(1) The salvage of existing topsoil is an important factor in revegetation and thus is a crucial part of the reclamation process.

(2) A detailed soil survey may be necessary to determine soil type and soil chemistry. The complexity of such a survey will depend upon site geology, vegetation, areal extent, and post-mining uses.

(3) In areas of good soil development, topsoil is a valuable asset and should be segregated for future use in revegetation. In some areas, because of poor or very limited soil conditions, it may be impractical or impossible to salvage soil.

(4) When the reclamation plan calls for resoiling, coarse hard mine waste shall be leveled and covered with a layer of finer material and weathered waste. A soil layer shall then be placed on this prepared surface.

(5) Mining operations that did not salvage soil during their initial operations shall attempt, where feasible, to upgrade remaining native materials. The use of soil conditioners, mulches, or imported topsoil shall be considered where revegetation is part of the reclamation plan and where such measures appear necessary. It is not justified, however, to denude adjacent areas of their soil, for any such denuded areas must in turn be reclaimed.

(g) Final Slope Gradient.

(1) The designed steepness and proposed treatment of the final slopes of the mined lands shall take into consideration the physical properties of the slope material, its probable maximum water content, seismic loading, landscaping requirements, and other pertinent factors.

(2) The maximum stable slope angle might range from 90 degrees in a sound limestone, igneous rock, or similar hardrock to less than 20 degrees in highly expansive clay. In all cases, reclamation plans shall specify slope angles flatter than the critical gradient for the type of material involved. The Committee will require a geotechnical analysis of the slope stability for any cut or fill slopes steeper than 2:1. Special emphasis on slope stability and design will be necessary when public safety or adjacent property may be affected.

(h) Backfilling and Grading.

(1) Most backfilling and grading is undertaken to store mine waste rock and overburden, to produce designed slopes, to establish drainage, or to raise the ground surface above the local water table. Any area mined to produce additional materials for backfilling and grading must also be included in the reclamation plan.

(2) Settlement of filled areas must be considered in all reclamation plans. Where probable ultimate site uses include roads, building sites, or other improvements sensitive to settlement, the reclamation plans shall include compaction of the fill materials in conformance with good engineering practice to avoid excessive settlement. Fill placement shall conform to local grading ordinances or, in their absence, the California Building Code.

(i) Revegetation. Before final revegetation is undertaken, the Operator shall make use of the available research addressing revegetation methods and the selection of species having good survival characteristics for the topography, resoiling characteristics, and climate of the area. Native species are required wherever possible. Reclamation plans may also include development of screens and roadside plantings at mines currently in operation, where such screens and plantings are practicable and desirable. [Ord. 27 § 6019, adopted, 6/27/2012.]