Proposal for Pilot Evaporation Pond

Home Browse Search

Paradox Valley Unit Proposal for Evaporation Pond and food sources at the nearby Dolores River and elsewhere to be more desirable and receive very little impact, if any, from the test evaporation pond. Review of Evaporation Ponds and Migratory Birds at Green River, Wyoming Several evaporation ponds,ranging in size between 225 and 1100 acres,are located about 20 miles west of the city of Green River in southwest Wyoming. These ponds hold tailings water from trona mining and refining processes for four mining companies. Trona is mined and processed with nahcolite and sodium carbonate-rich waters to form the commodity called"soda ash". The trona mines in this area produce 90 percent of the soda ash used in the United States and export it to countries around the world. Soda ash is used in a variety of manufacturing processes including glass products,paper products,detergents, solar panels, caustic soda,baking soda, sodium cyanide, and as a reagent for SO2 scrubber systems of power plants. Birds have been adversely affected by the sodium decahydrate and other chemical precipitates in the trona evaporation ponds. More than 2,000 bird deaths have been recorded at the ponds since 1975. A report by the USGS dated September 2004,titled"Investigation of Migratory Bird Mortality Associated with Exposure to Soda Ash Mine Tailings Water in Southwestern Wyoming,"lists three primary reasons for the bird deaths. First, sodium decahydrate crystals form on the feathers and allow water to penetrate the protective insulating function of the feathers, which leads to hypothermia and death. Second, significant accumulation of sodium decahydrate crystals on the feathers adds excessive weight to the bird, inhibiting movement and potentially causing drowning. Third, "physiologic toxicity"could potentially be caused by oral ingestion of the pond water. The tailings water at the trona ponds primarily contains sodium decahydrate and is highly alkaline(pH> 10.2). Other chemicals present in the water include sulfate,bicarbonate, chloride, calcium, aluminum, arsenic, boron, cadmium, and magnesium. Sodium decahydrate precipitates out of the water and crystallizes on birds and other solid objects in the ponds or on the water surface, generally at temperatures lower than 40 degrees F. Most of the trona ponds that attract large numbers of birds are in close proximity to the mine extraction/processing plants, and biologists hypothesized in the early 1970's that lights from the adjacent mine buildings were illuminating the ponds and attracting migratory birds traveling during the night to land on them. This hypothesis was raised again in the early 2000's by Dr. Joseph Jehl, biologist at Hubbs-Sea World Research Institute in San Diego, California, and is discussed in the September 2004 USGS report. The report states that the lighting of the ponds by adjacent buildings"may be the primary factor underlying the attraction of birds." Dr. Jehl pointed out that grebes fly at night during migratory seasons, and typically land on water in the early morning hours just prior to sunrise. (The 10