Piñon Ridge Uranium Mill Sets Permit Precedent

Issue 3 and Volume 4.

By Kris Allen and Louis Bridges, Kleinfelder

On Jan. 5, 2011, the Radiation Management Program of the Colorado Department of Public Health and Environment (CDPHE) issued its License Decision, approving a conditional radioactive materials license for a 500-ton-per-day uranium and vanadium mill to Energy Fuels Resources Corp. (EFRC).

The Piñon Ridge Mill is the first uranium mill to navigate the regulatory landscape in more than 30 years, setting the standard for mill licensing in the coming years.

(1) View looking south from the north end of the site during geotechnical drilling in October/November 2007 with Davis Mesa in the background.

EFRC partnered with Kleinfelder, an environmental and engineering consulting firm, to navigate the applicable health, safety and environmental protection permits from local, state and federal agencies and the health department’s approval of construction plans before building the mill; and they did it 25 percent faster than expected.

Mining inroads

EFRC selected the Piñon Ridge site, located in the heart of Colorado’s uranium mining district in western Montrose County, based on regulatory requirements, site conditions, access and proximity to occupied properties.

From this location, uranium ore could be milled near where it is mined. The proposed mill site is located in the Paradox Valley between the communities of Bedrock and Naturita. The mine location will prevent the need to haul the ore to other mills, often on lengthy routes over mountainous roads. The Paradox Valley has been the site of extensive mining activity in past years and there are several existing uranium mines near the mill site.

(2) Geotechnical drilling conducted on the mill site from October through December 2007. View looking northeast with Long Park Mesa in background.

The Piñon Ridge Mill will occupy approximately 400 acres of the 880 acres that EFRC owns. The proposed facility includes an administration building, a 17-acre mill, tailing ponds totaling approximately 90 acres, a 40-acre evaporation pond (expansion capacity to 80 acres), a roughly six-acre ore storage pad and access roads.

To establish baseline conditions, groundwater monitoring on the Piñon Ridge Uranium Mill site began soon after property acquisition in the fall of 2007. Surface water sampling began in early 2008. Four surface water samplers, designed specifically for this project, are installed in selected drainages on the site. The surface water was sampled on a run-off event basis, rather than a fixed calendar schedule, due to the intermittent nature of run-off events in the area.

Meteorological and air monitoring stations were installed both on and offsite to collect climate and air quality baseline data. Seismic reflection and refraction surveys were used to locate faults under the site.

A site-wide radiological survey was performed to characterize the pre-construction levels of radionuclides in the site soils and biota. Ecological surveys determined the location and distribution of wildlife and vegetation.

Operational objectives

The Piñon Ridge Mill will initially be built with a capacity to process 500 tons of uranium ore per day, with a projected life of 40 years. The ultimate design will accommodate an expanded capacity to 1,000 tons per day, if market conditions warrant and if proper regulatory approval is obtained. The mill will produce uranium and vanadium oxides that will be packaged in sealed 55-gallon drums and shipped to other facilities for further refinement and manufacturing.

The ore pad will be around six acres. The mill operating areas will include ore handling and grinding; leaching, thickeners and tailings disposal; uranium solvent extraction and precipitation; vanadium oxidation, solvent extraction and precipitation; and utilities.

Once they leave the pad, all trucks entering the restricted area will be washed at the onsite truck wash facility and screened for radiation prior to leaving the site. Unloading and handling the ore will use dust suppression methods. A winterized dust mitigation system will be built into the unloading area to mitigate fugitive dust.

Ore will be dumped into a feed hopper and delivered by belt conveyor to a semi-autogenous grinding (SAG) mill located in the main mill building (the grinding and leaching building). In the SAG mill, the ore will be combined with water and tumbled with steel balls. The grinding and leaching building, along with the pulp storage and pre-leach pad, will have concrete floors and concrete stem walls or curbs around their perimeters to provide secondary containment.

Abrasion/corrosion-resistant HDPE pipe will be used for process lines, while steel pipe will be used for water and compressed air lines. The tanks and sumps will be equipped with high- and low-level gauges and alarms that alert the control room and mill operators in the event of upset conditions.

Modern advancements

The proposed SAG mill is an advancement over earlier mills that used cone crushers or other crushing methods that released significant amounts of dust. The SAG mill will be enclosed and will not emit dust from an outdoor stack. This will reduce the potential of releasing radioparticulates to the environment. A zero-discharge vacuum dryer will be used to dry the uranium oxide, or “yellow cake” as it is commonly called. This replaces old-style calciners that were a source of uranium dust emissions in the past.

(3) View of PM-10 particulate matter air monitor and 30-meter meteorological tower (in background) located at southeast corner of the mill site. (Taken in March 2008)

All ore trucks and other pieces of equipment will be cleaned at the truck wash facility before leaving the mill restricted area. The truck wash will be a partially enclosed and automated touchless system consisting of a platform constructed of heavy-duty angle iron with high-pressure water sprays mounted both below and on the sides. The high-pressure sprays will remove dirt or mud tracked off the ore pad area and will require between one and two minutes to wash a truck.

The decommissioning funding plan (DFP) contains the decommissioning cost estimate for assuring funds for decommissioning, including means of adjusting cost estimates and associated funding levels periodically over the life of the facility. A reclamation and long-term care bond of approximately $12 million will be posted with the state of Colorado.

After review, the Radiation Management Program of the CDPHE issued a conditional radioactive materials license. The license can be amended and a periodic license renewal (usually every five years) is necessary to update information; verify proposed activities; validate the ability of the operator to operate within license requirements; and to protect workers, the public and the environment. Changes to operation, key personnel and other aspects of the activity will require a license amendment. CDPHE will conduct routine oversight of the facility during critical construction and start-up activities and through onsite inspections and review of documents and reporting.

(4) View looking up 30-meter meteorological tower located at southeast corner of the mill site. (Taken in January 2010)

Air Quality

In addition to the operating license, the facility is required to obtain an air quality permit. Efforts to support both of these requirements involved significant air quality expertise. To complete this successfully, the air quality team addressed several elements, including:

  • Acquire one year of baseline meteorological data
  • Acquire one year of baseline ambient air quality monitoring data for total suspended particulates (TSP), particulate matter less than 10 microns in diameter (PM10), and radionuclides;
  • Develop and approve a monitoring protocol
  • Prepare quarterly monitoring reports
  • Perform equipment calibration, verification, validation and operation procedures
  • Develop a regional climatology report
  • Evaluate impacts to climate change
  • Assess operations and emission sources
  • Perform first-of-its-kind control technology assessment for reducing potential organic emissions (no established control requirements had been identified since the enactment of the Clean Air Act due to no uranium mills being permitted in over 30 years)
  • Process the baseline data following guidance and policy to achieve a minimum 90 percent data capture (final approved data capture was near 100 percent);
  • Conduct modeling for near field impact analysis to demonstrate standards would not be exceeded; and
  • Assess long-range deposition impacts due to influences on regional dust storms.

To develop these data, the Piñon Ridge air quality team established a monitoring network consisting of five TSP air monitors, two PM10 monitors, a 10-meter meteorology tower and a 30-meter met tower to comply with both Clean Air Act and Nuclear Regulatory Commission regulations.

The site is located in a remote valley, which presented numerous challenges such as harsh winter conditions, access difficulties and providing power for the air samplers and met towers.

However, the team dealt with these challenges and established the installation and operation of the monitoring equipment. The equipment obtained critical information, including wind speed and direction, humidity, temperature, solar radiation, precipitation, background ambient air concentration data and radioactive data, to name a few. These data met a data capture requirement and were used to establish a pre-project background level, conduct modeling and assess long-range deposition impacts.

The air dispersion model and permit applications are currently in review and must be approved before EFRC can begin constructing the Piñon Ridge mill. All technical issues have been addressed and it is anticipated the permit will be issued soon.

Authors: Kris Allen is a project manager and air quality specialty leader with Kleinfelder. Louis J. Bridges, PhD, is a principal professional for environmental planning and permitting with Kleinfelder.

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