Water Management / Air Quality

Water Management

The company maintains water-management systems, including water-management ponds and a water-treatment plant, so any stormwater and groundwater intercepted by the TDF control structures and liner system will be treated so that it complies with discharge standards set by the company’s Alaska Pollutant Discharge Elimination System (APDES) permit for the site prior to release.

Goal: Minimize impacts to surface and groundwater quality and the hydrology of the area

Actions:

  • Stormwater will be managed through the construction and maintenance of diversion channels to route precipitation runoff away from the TDF. Contact water will be captured and treated before discharge into Hawk Inlet, in compliance with the company’s APDES permit.
  • Water bars, culverts, wattles, diversion ditches, diversion tubes, stormwater-detention basins, stormwater ponds, re-vegetation, rock armoring, hydro-seeding, weed-free jute matting, silt fencing, swales and other erosion-control techniques will be utilized to reduce erosion and soil loss.
  • Culverts and ditches along roads will be inspected and maintained.
  • Direct runoff from the TDF will be routed and managed at appropriate collection sites to prevent contact-water runoff into surface water bodies.
  • Vehicles will have their wheels cleaned at the designated wheel-wash facility prior to leaving the tailings disposal area (TDA).
  • Erosion-control measures (e.g., silt fences, swales, and weed-free jute matting) will continue to be used to slow water and reduce erosion while vegetation becomes established.
  • Hydroseeding will be used on channel banks to aid in stabilization; channels will be stabilized using techniques such as degradable fiber mats to establish vegetation and riprap to stabilize constructed channels.
  • Slopes and road cuts will be monitored for exposed soil and appropriate measures (e.g., hydroseeding) will be applied as appropriate to minimize erosion.
  • Covers, liners and surface-water diversions will be installed in the TDA to minimize tailings contact with surface water and groundwater.
  • Water-management infrastructure will be maintained as needed to treat contact water.

Air Quality

The project is located in an isolated, remote area but is subject to windblown dust generated from exposed tailings, especially during the winter months from the northerly winds.

Goal: Manage air emissions to protect human health and the environment during construction, operation, closure and reclamation.

Actions:

  • Hecla Greens Creek will design, construct and operate project facilities in compliance with appropriate air-pollution controls to comply with applicable regulations and any air-quality permits issued by the Alaska Department of Environmental Conservation (ADEC).
  • Applicable state and federal air-quality standards will be met through the use of best available control technology to control emissions, as required by ADEC.
  • Dust abatement and monitoring will be implemented to investigate the source and extent of fugitive dust to minimize dispersion and mobilization of tailings from the TDF.
  • Dust control will be implemented on roads during dry periods involving periodic watering, or the use of surfactants or other methods to control fugitive-dust generation.
  • Internal and external roads to the TDF will be maintained by motor grader. Smooth and clean road surfaces are essential for not only minimizing dust but to allow for efficient, safe and economical use of roads. The B-Road will be periodically re-surfaced with crushed rock/gravel imported from off-island sources.
  • Dust control will be implemented on the tailings pile through operational sequencing, interim re-vegetation, temporary storage of reclamation material (soil/peat), placement of snow fences, watering systems, and chemical agent as approved.
  • Haul trucks will be inspected to ensure covers are in place and tailgate latches are secured to avoid spillage of material.