Northern Dynasty applies for water rights

In its application for water rights for the Pebble project, Vancouver-based Northern Dynasty reveals details of its environmental baseline studies and proposed mine facilities. Northern Dynasty filed the application with the state of Alaska's Department of Natural Resources in mid-July, providing three hefty folders of information regarding the North Fork Koktuli, the South Fork Koktuli and the Upper Talarik Creek watersheds in the Bristol Bay area.

The state will likely request additional material from Northern Dynasty before taking a decision on whether to grant water rights, according to DNR. Alaska statutes require that the proposed use of water be beneficial and in the public interest. In determining the public interest, the DNR commissioner must consider factors such as the benefit to the applicant, the effect of the proposed economic activity, the effect on fish and game resources and public recreational opportunities, the effect on public health and the effect on access to navigable or public water.

Northern Dynasty's application states that the expected date for water use to begin is approximately June 2010, and the expected date for water use to be fully developed is approximately November 2012.

Applying for water rights at this early stage of the mine development process - permit applications are not expected to be filed until January 2008 - is a standard practice for mining companies, according to Northern Dynasty.

"Applying for water rights in advance of developing a final mine plan will provide Northern Dynasty engineers and environmental scientists with the greatest flexibility to mitigate potential impacts on fish and fish habitat," the company said in a briefing note July 17.

Some groundwater flow will be cut off

Development of the mine site will modify catchment hydrology, the water rights application says. Construction of the tailings dam will cut off groundwater flow from some areas, and development of the site will reduce interception and transpiration by vegetation, increasing runoff. Existing vegetation at the site is predominantly low shrubs, grasses and mosses. Northern Dynasty's goal is to continuously recycle water so that no process water is released to the downstream environment.

The tailings storage facility will cause increases to evaporation in the summer and wind-blown snow transport and sublimation in winter, resulting in a net increase to water loss from the catchment, the application says. Global warming over the next few decades will also increase evapotranspiration and sublimation rates in the area, and less precipitation will fall as snow. These effects suggest that water quantity at the site will reduce over the mine life, Northern Dynasty says.

If the Pebble project proceeds, development will require capture of surface and groundwater flows at the site. This water will be used for "beneficial mining uses," Northern Dynasty says, including mill operations and tailings slurry transport, providing potable water, ensuring that fluctuations in the tailings pond do not impact the mining process, and protecting downstream aquatic resources - for example by submerging potentially reactive waste materials, and controlling sediment.

Tailings storage for 500 million tons

The tailings storage facility has been designed to store approximately 500 million tons of tailings and potentially reactive waste rock, as well as mill process water and site runoff, the application says.

The flotation process will create two separate tailings streams: a bulk tailings stream, accounting for around 97 percent of the total, and a pyritic tailings stream, accounting for the remaining 3 percent.

The bulk tailings, which test work has shown to be non-reactive, will be discharged from delivery pipelines located along the embankment crests and adjacent high ground.

The pyritic tailings, which will be potentially acid generating if allowed to oxidize, will be deposited below ponded water to prevent oxidation.

If DNR grants the water rights to Northern Dynasty, the company will have legal standing to assert the rights against conflicting water users who do not have water rights. The company will also have priority to use water over anyone who later files for water rights from the same source. The Pebble project is already facing strong opposition from local residents who engage in commercial, sport or subsistence fishing, as well as from environmental organizations.