Idaho Admin. Code r. 20.03.01.040

Current through September 2, 2024

Section 20.03.01.040 - BEST MANAGEMENT PRACTICES AND RECLAMATION FOR PLACER AND DREDGE MINING OPERATION

01.Pollution Control.

a. Appropriate best management practices for nonpoint source sediment or other pollution controls must be designed, constructed, and maintained with respect to site-specific placer or dredge mining operations.

b. State water quality standards, including protection of existing beneficial uses, are the standard that must be achieved by best management practices. In addition to proper mining techniques and reclamation measures, the Permittee will take necessary steps at the close of each operating season to assure that sediment movement or other pollution associated with surface runoff over the area is minimized in order to achieve water quality standards.

c. Sediment or pollution control measures refer to best management practices that are carried out within and, if necessary, adjacent to the disturbed land and consist of utilization of proper mining and reclamation measures, as well as specific necessary pollution control methods, separately or in combination. Specific pollution control methods may include, but are not limited to:

i. Keeping the disturbed land to a minimum at any given time through concurrent reclamation;

ii. Shaping waste to help reduce the rate and volume of water runoff by increasing infiltration;

iii. Retaining sediment within the disturbed land;

iv. Diverting surface runoff to limit water coming into the disturbed land and settling ponds;

v. Routing runoff through the disturbed land using protected channels or pipes so as not to increase sediment load;

vi. Use of riprap, straw dikes, check dams, mulches, temporary vegetation, or other measures to reduce overland flow velocities, reduce runoff volume, or retain sediment; and

vii. Use of adequate sediment ponds, with or without chemical treatment.

02.Modification of Best Management Practices. If best management practices utilized by the Permittee do not result in compliance with Subsection 040.01, the Director will require the Permittee to modify or improve such best management practices to meet state water quality standards.

03.Clearing and Grubbing. Clearing and grubbing of land in preparation for mining exposes mineral soil to the erosive effects of moving water. Permittees are cautioned to keep such areas as small as possible (preferably no more than one (1) year's mining activity) as the Permittee is required to meet state water quality standards. Trees and slash should be stockpiled for use in seedbed protection and erosion control and such stockpiling may be a requirement of the approved permit.

04.Overburden/Topsoil. To aid in the revegetation of disturbed land, where placer or dredge mining operations result in the removal of substantial amounts of overburden, including any topsoil, the Permittee must remove, where practicable, the available topsoil or other growth medium as a separate operation for such area. Unless there are previously disturbed lands which are graded and immediately available for placement of the newly removed topsoil or other growth medium, the topsoil or other growth medium must be stockpiled and protected from erosion and contamination until such areas become available.

a. Overburden/topsoil removal:

i. Any overburden/topsoil to be removed will be removed prior to any other mining activity to prevent loss or contamination;

ii. Where overburden/topsoil removal exposes land area to potential erosion, the Director may, as a condition of a permit, limit the size of any one (1) area having topsoil removed at any one (1) time; and

iii. Where the Permittee can show that an overburden material other than topsoil is more conducive to plant growth, or where overburden other than topsoil is the only material reasonably available, such overburden may be allowed as a substitute for or a supplement to the available topsoil.

b. Topsoil storage. Topsoil stockpiles must be placed to minimize rehandling and exposure and to avoid excessive wind and water erosion. Topsoil stockpiles must be protected, as necessary, from erosion by use of temporary vegetation or by other methods which will control erosion including, but not limited to, silt fences, chemical binders, seeding, and mulching.

c. Overburden storage. Stockpiled ridges of overburden must be leveled to a minimum width of ten (10) feet at the top. Peaks of overburden must be leveled to a minimum width of fifteen (15) feet at the top. The overburden piles must be reasonably prepared to control erosion using best management practices such as terracing, silt fences, chemical binders, seeding, and mulching.

05.Roads.

a. Roads must be constructed to minimize soil erosion. Such construction may require, but is not limited to, restrictions on length and grade of roadbed, surfacing of roads with durable non-toxic material, stabilization of cut and fill slopes, and other techniques designed to control erosion.

b. All access and haul roads must be adequately drained. Drainage structures may include, but are not limited to, properly installed ditches, water-bars, cross drains, culverts, and sediment traps.

c. Culverts that are to be maintained for more than one (1) year must be designed to pass peak flows from not less than a twenty (20) year, twenty-four (24) hour precipitation event and have a minimum diameter of eighteen (18) inches.

d. Roads and water control structures must be maintained at periodic intervals as needed. Water control structures serving to drain roads may not be blocked or restricted in any manner to impede drainage or significantly alter the intended purpose of the structure.

e. Roads that are to be abandoned must be cross-ditched, ripped, and revegetated or otherwise obliterated to control erosion.

f. Roads that will be used under the jurisdiction of a governmental or private landowner after reclamation is completed are the Permittee's responsibility under Subsection 040.01 until the successor assumes control.

06.Settling Ponds -- Minimum Criteria.

a. Settling ponds must provide adequate sediment storage capacity to achieve compliance with applicable water quality standards and protect existing beneficial uses, and may require periodic cleaning and proper disposal of sediment.

b. No settling pond, used for process water clarification may be constructed to block a surface water drainage.

c. All settling ponds will be constructed and designed to prevent surface water runoff from entering the pond.

d. All settling ponds will be constructed and maintained to contain direct precipitation to the pond surface from a fifty (50) year twenty-four (24) hour storm event.

e. No chemicals may be used for water clarification or on site gold recovery without prior notification to, and approval from, the DEQ.

07.Dewatering Settling Ponds. Upon reclamation, settling ponds must be dewatered, detoxified, and stabilized. Stabilization includes regrading to the approximate original contour, and may require removal and disposal of settling pond contents.

08.Backfilling and Grading.

a. Every operator who conducts placer mining exploration operations that disturb less than one-half (1/2) acre must contour the disturbed land to its approximate previous contour. These lands must be revegetated in accordance with Subsection 040.15. For showing discovery on federal mining claims, unless otherwise required by a federal agency, one (1) pit may be left open on each claim pending verification by federal mining examiners, but must not create a hazard to humans or animals. Such pits and trenches must be reclaimed within one (1) year of verification.

b. Every Permittee who disturbs more than one-half (1/2) acre must shape and smooth the disturbed ground to a grade reasonably comparable with the natural contour of the ground prior to mining, and to a condition that promotes the growth of vegetation except as provided in Paragraph 040.15.m. or minimize erosion through other means. Any disturbed natural watercourse must be restored to a configuration and structure conducive to good fish and wildlife habitat and recreational use.

c. Backfill materials must be compacted in a manner to ensure stability of the fill.

d. After the disturbed land has been graded, slopes will be measured by the Department for compliance with the requirements of the Act, these rules, and the permit.

09.Waste Disposal -- Disposal of Waste in Areas Other Than Mine Excavations. Waste materials not used in backfilling mined areas must be placed, stabilized, and revegetated to ensure that drainage is compatible with the surrounding drainage and to ensure long-term stability.

a. The Permittee may, if appropriate, use terraces to stabilize the face of any fill. Slopes of the fill material may not exceed the angle of repose.

b. Unless adequate drainage is provided through a fill area, all surface water above a fill must be diverted away from a fill area into protected channels, and drainage may not be directed over the unprotected face of a fill.

10.Topsoil Redistribution. Topsoil must be spread to achieve a thickness over the regraded area, adequate to support plant life. Excessive compaction of overburden and topsoil is to be avoided. Topsoil redistribution must be timed so that seeding or other protective measures can be readily applied to prevent compaction and erosion. Final grading must be along the contour unless such grading will expose equipment operators to hazardous operating conditions, in which case the best alternative method must be used in grading.

11.Soil Amendments. Nutrients and soil amendments will be applied as needed to the graded areas to successfully achieve the revegetation requirements of the permit.

12.Revegetating Waste Piles. The Permittee must conduct revegetation activities with respect to such waste piles in accordance with Subsection 040.15.

13.Mulching. Mulch should be used on severe sites and may be required by the permit. Nurse crops such as rye, oats, and wheat may be used as a substitute for mulch where they will provide adequate protection and will be replaced by permanent species within a reasonable length of time.

14.Permanent Cessation and Time Limits for Planting.

a. Wherever possible, but not later than one (1) year after grading, seeding and planting of disturbed lands will be completed during the first favorable growth period after seedbed preparation. If permanent vegetation is delayed or slow in establishment, temporary cover of small annual grains, grasses, or legumes may be used to control erosion until adequate permanent cover is established.

b. Reclamation activities should be concurrent with the mining operation and may be included in the approved permit. Final reclamation of the permit area or any part of the permit area must begin within one (1) year after the placer or dredge mining operations have permanently ceased on those parts of the permit area.

c. A Permittee will be presumed to have permanently ceased placer or dredge mining operations on a given portion of disturbed land where no substantial amount of mineral or overburden material has been removed or overburden placed on an overburden dump, or no significant use has been made of a road during the previous one (1) year.

d. If a Permittee does not plan to use disturbed land for one (1) or more years, but intends thereafter to use the disturbed land for placer or dredge mining operations, and desires to defer final reclamation until after its subsequent use, the Permittee must submit written a notice of intent and request for deferral of reclamation to the Department. If the Department determines that the Permittee plans to continue the operation within a reasonable period of time, the Department will notify the Permittee and may require actions to be taken to stabilize stockpiles and maintain water quality until operations resume. If the Department determines that the use of the disturbed land for placer or dredge mining operations will not be continued within a reasonable period of time, the Department will proceed as though the placer or dredge mining operation has been abandoned, but the Department will notify the Permittee of such decision at least thirty (30) days before taking any formal administrative action.

15.Revegetation Activities.

a. The Permittee must select and establish plant species that can be expected to result in vegetation comparable to that growing on the disturbed lands prior to placer or dredge mining operations or other species that will be conducive to the post-mining use of the disturbed lands. The Permittee may use available technical data and results of field tests for selecting seeding practices and soil amendments that will result in viable revegetation.

b. Standards for success of revegetation. Revegetative success, unless otherwise specified in the approved placer mining permit, is measured against the existing vegetation at the site prior to mining, or an adjacent reference area supporting similar vegetation.

c. The ground cover of living plants on the revegetated area must be comparable to the ground cover of living plants on the adjacent reference area for two (2) full growing seasons after cessation of soil amendment or irrigation.

d. For purposes of this rule, ground cover is considered comparable if it has, on the area actually planted, at least seventy percent (70%) of the premining ground cover for the mined land or adjacent reference area.

e. For locations with an average annual precipitation of more than twenty-six (26) inches, the Director, in approving a placer mining permit, may set a minimum standard for success of revegetation as follows:

i. Vegetative cover of seventy percent (70%) for two (2) full growing seasons in areas planted to herbaceous species only; or

ii. Fifty percent (50%) vegetative cover for two (2) full growing seasons and six hundred (600) woody plants per acre in areas planted to a mixture of herbaceous and woody species.

f. As used in this section, "herbaceous species" means grasses, legumes, and other forbs; "woody plants" means woody shrubs, trees, and vines; and "ground cover" means the area of the ground surface covered by the combined aerial parts of vegetation and the litter that is produced naturally on-site, expressed as a percentage of the total area measurement. Rock surface areas, composed of rock three plus (3+) inches in diameter will be excluded from this calculation. For purposes of measuring ground cover, rock greater than three (3) inches in diameter is considered as ground cover.

g. Previously mined areas that lack sufficient topsoil and are re-disturbed by a placer or dredge mining operation are not required to meet the revegetation standards in Section 040, but vegetation must be established to the extent necessary to control erosion and may not be less than that which existed before re-disturbance.

h. Introduced species may be planted if they are comparable to previous vegetation, or if known to be of equal or superior use for the approved post-mining use of the disturbed land, or, if necessary, to achieve a quick, temporary cover for soil stabilization purposes. Species classified as poisonous, noxious weeds, or invasive may not be used in revegetation.

i. By mutual agreement of the Department, the landowner, and the Permittee, a site may be converted to a different, more desirable, or more economically suitable habitat.

j. Planting of grasses and forbs should be done in a manner which promotes rapid stabilization of the soil surface. Wherever terrain permits, grasses and forbs should be drilled or compacted into the ground using agricultural grass planting equipment or other seeders specifically designed for mine revegetation applications. Broadcast and hydroseeding may be used on areas where other methods are impractical or unavailable.

k. The Permittee should plant shrubs or shrub seed, as required, where shrub communities existed prior to mining. Shrub seed may be planted as a portion of a grass seed mix or planted as bare-root transplants after grass seeding. Where the landowner desires a specific land use such as grazing or cropland, shrubs will not be required in the revegetation species mix. Shrub lands undergoing revegetation with shrubs must be protected from erosion by vegetation, chemical, or other acceptable means during establishment of the shrubs.

l. Reforestation -- Tree stocking of forestlands should meet the following criteria:

i. Trees that are adapted to the site should be planted on the land to be revegetated, in a density which can be expected over time to yield a timber stand comparable to premining timber stands. This in no way is to exclude the conversion of sites to a different, more desirable, or more economically suited species;

ii. Trees must be established for two (2) full growing seasons after cessation of any soil amendments and irrigation before they are considered to be established; and

iii. Forest lands undergoing revegetation with trees should be protected from erosion by vegetation, chemical binders, or other acceptable means during seedling establishment.

m. Revegetation is not required on the following areas:

i. Disturbed lands, or portions thereof, where planting is not practicable or reasonable because the soil is composed of excessive amounts of sand, gravel, shale, stone, or other material to such an extent to prohibit plant growth;

ii. Any mined land or overburden piles proposed to be used in the mining operations;

iii. Any mined land or overburden pile, where lakes are formed by rainfall or drainage run-off from adjoining lands;

iv. Any mineral stockpile;

v. Any exploration trench which will become a part of any pit or overburden disposal area; and

vi. Any road which is to be used in mining operations, so long as the road is not abandoned.

Idaho Admin. Code r. 20.03.01.040

Effective July 1, 2024