What do you do with 110,000 tons of salt a year?
That’s a question Bureau of Reclamation officials are pondering as they mull the future of critical salinity-treatment efforts on the Lower Dolores River near the Utah state line.
For the past decade and a half, the bureau has been putting the salt into a very deep well. But the well is nearing the end of its useful life, and officials are now considering whether to drill a new one or try another approach.
“The well is starting to fill up,” said Terry Stroh, a biologist and NEPA compliance officer with the bureau’s Grand Junction office. “We’re not going to be able to inject there any longer. We’ll either have to drill another well or do something else.”
The facility that treats brine on the Dolores sits in the Paradox Valley, which was formed from the collapse of a salt dome, or anticline. Historically, as the Dolores meandered through the valley, it picked up more than 200,000 tons of salt.
The Colorado River Basin Salinity Control Act of 1974 authorized the Secretary of the Interior to establish programs both upstream and downstream from the Imperial Dam on the California-Arizona border to protect and improve the quality of the Colorado River.
One such program was the Paradox Valley Unit, which is designed to intercept briny groundwater before it enters the river, remove the salts, and deposit them in an injection well.
The unit is near Bedrock, Colo., about halfway between Cortez and Grand Junction.
The facility includes nine production wells 40 to 70 feet deep that pump 30 to 120 gallons per minute; four injection pumps working at 115 gallons per minute; and a 16,000- foot well, the deepest injection well in the world.
“I know this is the only facility of its kind where we’re pumping the brine into the earth, so it’s a unique facility,” said Justyn Hock, public-affairs specialist for the Western Colorado office of the Bureau of Reclamation.
It’s unique, too, in that the deep injection of salts has caused some low-scale seismic activity over the years, though not many of those mini-earthquakes could actually be felt.
“I haven’t been down there when one happened, but what I understand is that most of them you can’t even feel,” said Hock. “We’ve had a couple bigger ones where maybe a cup falls off somebody’s table, but nothing damage-causing.
“It’s just the [tectonic] plates shifting as we’re pumping the brine in there.”
The annual disposal rate of the entire unit is 110,000 tons of (dry-weight) salt every year – about seven railroad cars’ worth a day, Stroh said. Since 1996, the unit has removed a total of more than 1.6 million tons of salt from the river. It makes up 10 percent of the salt-control measures now in place on the Colorado River system, according to the bureau.
The Paradox Valley Unit has an annual operations budget of about $2.8 million per year, according to the Bureau of Reclamation’s web site.
But the injection well is expected to fill some time in the next decade, Stroh said, so officials need to decide whether to drill another one or do something else with the salts.
The bureau is currently doing public scoping to evaluate potential issues and concerns with a proposed pilot study to see whether evaporative ponds might be a viable disposal method. In December, public meetings were held in Paradox and in Montrose to gather comments, and the bureau is taking written comments until Jan. 30.
The pilot study, if it gets the go-ahead, would involve constructing and operating one or more evaporation ponds of 1 to 15 acres in size (the total area involved won’t exceed 40 acres) to which the brine would be piped. The study would continue for three to five years to evaluate evaporation rates, operational costs and potential adverse impacts to birds, Stroh said.
The Colorado River Basin Salinity Control Forum, which is made up of representatives from the seven states in the river basin, requested the pilot study.
“The salinity forum has asked us to look at evaporative ponds again,” Stroh said.
After scoping, a draft environmental assessment will be developed for the pilot study, and if it ultimately gets the goahead, the study will be conducted.
An advantage of the ponds is that they might be cheaper than drilling another well. That will depend on a number of factors, however.
One of the biggest concerns is potential impacts on migratory birds, which are strictly protected under the Migratory Bird Treaty Act of 1918. During the pilot study, it will be ascertained whether birds can be kept away from the ponds through methods such as coloring the brine and employing noise cannons and flashing lights to deter birds from landing.
Netting can be installed if other techniques fail, but it would likely mean that the evaporative ponds would not be a viable alternative, because netting would reduce evaporation rates and isn’t feasible on a large scale.
“If there are effects we want to find other methods than netting because of the size of the netting and the scale,” Stroh said.
Another issue the bureau must considered is where the ponds would be located. Stroh said officials will be looking at places fairly close to the brine-treatment facilities.
However, it’s more difficult than one might imagine, even in the remote Paradox Valley, to find an appropriate site.
The state regards the salt evaporate as a non-hazardous solid waste. If it is to be stored long-term on Bureau of Reclamation or BLM land, that land would have to be withdrawn from the public domain because it is illegal to have landfills on public land. Withdrawal from public domain is “a long process with no guaranteed outcome,” Stroh said.
And hauling the evaporate somewhere else would likely be very expensive.
“We have looked at hauling the salt out and storing it within a permitted landfill, but there is nothing closer than Nucla, and I don’t think that one meets the state’s requirements for the salt,” Stroh said.
Different storage sites on federal land are being considered, he said. However, there are potential concerns with all of them, including possible contamination of underlying aquifers, proximity to the river and floodplain, and conflicts with ranching, wildlife (including the rare Gunnison sage grouse), and uranium exploration.
Yet another issue to evaluate is what will be done with the salt once the water has been evaporated out of it.
One might imagine that the salt could be useful – for de-icing roads, if nothing else. But as it turns out, this salt isn’t particularly good for anything.
It doesn’t contain enough potassium carbonate to make it good for fertilizer, Stroh said, and there it doesn’t have enough calcium carbonate to make it ideal for road use. And it certainly isn’t table-salt caliber.
“It’s mostly sodium chloride with trace elements that would have to be removed. The cost of removing it would be pretty high,” Stroh said.
“Most table salt comes from mines where it’s pure. The only potential for this would be road salt, and the market’s pretty saturated, but we will look at that in the alternatives.”
“It’s a low-cost product that costs a lot to produce.”
In the past, the bureau has tried to explore commercial potentials for the salt, but with little luck.
“In the ’70s we could put it on a railroad car and still couldn’t get anybody to take it,” Stroh said.
If the pilot study of evaporative ponds is approved and is concluded, the next step for the bureau will be preparing a full-blown environmental impact statement to evaluate all possible alternatives for disposal of the salt.
So far there haven’t been many comments pouring in, according to Hock.
“We’re trying to keep everybody involved from the beginning,” she said.
Salinity control is enormously important in the Colorado River Basin.
According to information from the Natural Resources Conservation Service, more than 33 million people in the United States and another 3 million in Mexico depend on Colorado River water for municipal, agricultural and industrial use. Salts carried in the Colorado River cause more than $300 million in damage each year.
Bureau of Reclamation and U.S. Department of Agriculture salinity-control efforts take more than 1 million tons of salt out of the river and its tributaries annually.