Salt wells gave Hutch that sinking feeling

Sunday, September 27, 1987

On the morning of May 15, 1914, a circular area 150 feet across on the grounds of the Morton salt plant in South Hutchinson dropped 15 feet in three hours, demolishing two abandoned buildings and five of the plant's cold brine tanks.

Since the solution mining of salt - in which water is used to dissolve and extract the salt - pulls thousands of tons of sodium chloride from the ground and leaves only water behind, some people speculated at the time that perhaps all that missing salt had something to do with the mishap.

Did the salt miners of Hutchinson admit this possibility?

"There were wild rumors afloat yesterday and last night," wrote the trusting Hutchinson News, "that the settling was due to the crust of rock above the salt cavity breaking ..."

(It was.) "... But experienced salt men, Frank Vincent, Emerson Carey and others, laughed at the theory. They maintain that there has been no crumbling of the rock, but that the settlement was due to local conditions of washing out of quicksand under this particular limited area."

The experienced salt men were still blaming the Arkansas River when the salt well into which all the rock, sand and shale had been crumbling started gushing its brine 12 to 13 feet into the air from the pressure.

Morton men capped the gusher, plugged the old wells, and filled and leveled the sinkhole with sand. Then they tried to forget about it all.

But at one time or another, all the major extractors of Hutchinson salt have been visited by Mother Earth's revenge against the salt trade: the sinkhole.

Modern brine mining is carefully controlled to avoid this phenomenon. Salt wells are used for a set number of years, under controlled conditions, and are monitored from time to time with sonar to see whether any areas are being undermined that could cause the property values overhead - and everything else overhead, for that matter - to drop.

When a salt company finishes with a well today, it leaves it full of brine and plugs the well pipe with concrete - leaving the ground about as stable as before it started.

But a dozen salt companies begun in Hutchinson before the turn of the century had no such technology, and no idea that it was needed. Even 10 years after the subsidence at Morton, the Carey Salt Co. was still operating a solution mine in downtown Hutchinson _ until the old Reno County Courthouse on South Main began a slow drop of about 21/2 feet that eventually caused the building to be evacuated and torn down.

In June 1952, another old well _ one of the ones drilled by the old Gouinlock & Humphrey plant, the first salt company to open in Hutchinson _ began to bring down the open ground above it near the Barton Salt Co. plant. Barton workers re-opened the well and plugged it, but instead of quieting, the ground continued to subside for more than 20 years, occasionally requiring Barton Co. to use sand fill on its driveway area.

But the granddaddy of all Hutchinson sinkholes was a monster that eventually opened to 500 feet wide and 70 feet deep near the Barton plant, which had just been purchased by Cargill, in southeast Hutch.

The ground began to subside on the morning of Oct. 21, 1974, and by that afternoon, three sections of railroad tracks and part of a box car were hanging 30 feet in the air over a widening hole. As the hole expanded, Cargill had to hire 24-hour Pinkerton guards to keep back crowds of sightseers, and since it quickly filled with water there was speculation the cavity might extend hundreds of feet into the salt bed itself.

It didn't, as it turned out. The hole, Hutchinson's most recent major sink, was plugged in 1980 after geologists had determined that it had stabilized - and wasn't likely to eat the work crews.

The salt business, according to local Cargill chief Jerry Rohlfson, is not high-tech.

"We're not making computer chips here," he says.

Automation may have streamlined work forces, and the vacuum evaporators of today may out-perform the vacuum evaporators of the 1920s, but the essentials of the salt-extraction business have not changed particularly in 50 years. The principles used today to manufacture 99.8 percent pure table salt were understood in ancient China and medieval Europe.

Most of the salt produced in the United States each year is obtained not from salt mines, but from solution mining. in Hutchinson all three salt companies - Cargill, Carey and Morton - get salt this way.

In modern solution mining two wells are drilled into the salt bed from the surface, and hot water is forced down one of them. in the salt bed each gallon of water dissolves about 21/2 pounds of salt and a trace of other chemicals, but rocks and sand are left behind.

Once the well fills with water, new water forced down the pipe pushes brine up the second pipe to the surface.

Once the brine is above ground, pipes carry it into the plant and into a vacuum evaporator.

And the vacuum evaporator, which first appeared around 1900, is the only big leap in technology to grace salt production in this century.

In older techniques salt water was evaporated from open pans, called "grainers," by using a coal or wood fire built directly under the pans to boil the water away and leave the salt behind.

Vacuum evaporation uses the same principle, but takes advantage of the phenomenon (known to all natives of Denver) that water boils more easily where the air is thinner. By heating brine at lower pressure, manufacturers use less energy to produce their salt.

Even so, however, salt plants are still warm places to make a living.

"I'd guess this room is probably about 110," said Dick Wilson, manager at Morton, as he led visitors past bulky evaporators on the plant's second floor.

"In the wintertime this is a very pleasant place."

These days heat is supplied by gas furnaces instead of coal fires, but it still amounts to an enormous investment each year by the plants. Since long before the energy crisis, Wilson said, salt companies have been looking for ways to use heat more efficiently.

Steam and hot water from the boilers is reused in every plant.

What comes out of the evaporators is not dry salt, but a milky slurry of crystallized sodium chloride and brine. The slurry is channeled into a machine called a rotary filter wheel and rotated on a wire screen while air heated to between 300 and 600 degrees is blasted through it.

After that it's pretty dry. You would be too.

The salt is dried further, if necessary, then separated into different grades for further processing or packaging. The Morton plant manufactures its trademark round blue cans of table salt and packs them on the premises.

Some industries require salt in bulk; for them, the salt is poured directly into bulk or boxcars that hold 60 to 100 tons of salt. Trucks can hold up to 24 tons.

For feeding stock, salt is pressed into 50-pound blocks with a press that can exert up to 25,000 pounds of pressure. Blocks come in a variety of colors and may contain sulfur, iodine or iron oxide; some contain molasses to make them more appetizing to stock.

At the Morton plant there are over 100 formulations or screen grades of salt; Barton features XX, Carey XX. Different grades all have their assigned uses: some very fine ones are used primarily in snack foods.

One strange-seeming packaging method for salt is the "super-sack" a one-ton bag of salt made of woven polyester. Food processing companies who need a lot of salt _ but not quite a box-car full _ order the semi-bulk bags.

Maintenance is a big concern at all three salt companies. Salt, as most drivers know, is not always a preservative. A winter of wet, salty roads can wreak havok on a car; by the same token a year-round bath in wet, salty air corrodes everything metal it touches in the plants.

"Salt just really tears things up," said David Merriweather, a chemist in Cargill's quality department, gesturing to an iron railing that looks like it might have been installed in the 1940s. The section of the plant it stands in is no older than 1973.

"I don't know how old this is, but it's not as old as it looks."