RUSSELL COUNTY, Kan. (KSNW) – Everyday more than 11,000 vehicles drive over a section of Interstate 70 in Russell County that is actually sinking into the earth. It is a product of years of oil drilling some eight decades ago, but it’s turned into a big cost for Kansas taxpayers who keep pouring money into the sinkholes.
For people driving over them, it doesn’t look much different from any other stretch of the highway. But, a view from above makes it clear, they are speeding over sinkholes.
KDOT Regional Geologist Neil Croxton explains why the area has sinkholes.
“The whole area, for hundreds of feet is slowly settling and our highway just happens to be close to there.”
To understand the cause you’ve got to go back to the 1920’s, a time of abundant oil and few state regulations, which led to robust oil production. By the 40’s many of those oil well sites were abandoned and Croxton says that’s when the problem was created.
“Whatever plugging was done, if anything was done, was not successful,” said Croxton.
Geologists explain that those oil wells punched through hundreds of feet of sandstone beds, through fresh water, shale and then hit thick salt deposits to get to the oil. Normally, the water never gets anywhere near the salt, but, these oil wells punched through that. Croxton explains what happened next.
“This is just like table salt, it dissolves just as easily as the salt you use around the house,” said Croxton.
When the salt dissolved, it created voids underground. Fast forward a couple of decades to 1966, when the Kansas Highway Commission was preparing to open Interstate 70, crews discovered that what it thought was a pond by the road, was a significant sinkhole created from one of those abandoned oil well sites. It was known as the Crawford. Then, the state discovered two more sinkholes, the Witt and the Roubach.
“When this was discovered, there was serious talk of realigning the highway, it was a big problem and a big embarrassment quite frankly,” said Croxton.
But, the state didn’t move the highway, instead crews filled the hole and hoped for the best.
“This was just written off as a peculiarity and it was forgotten about. It was filled in during construction but, it reformed again shortly after the highway opened,” said Croxton.
Today, more than 50 years after it was discovered, it’s still sinking.
“It’s still a concern we keep an eye on,” said Croxton.
The state has spent millions over the years, to build the area back up. In 1971, the state put five feet of fill into the Crawford and Witt sinkholes at a cost of $220,000. In 1984, another eight feet had to be filled in at the Witt site for a cost of $500,000. Just a few years later in 1986 and 1988, cement was pumped into the Witt site, for $88,400 dollars.
But, Kevin Zimmer, KDOT Area Engineer says the ground continued to sink creating a very low point on the interstate.
“When a car let’s say was driving eastbound or even a semi-truck, vehicles behind them, if you were in the right spot you would actually lose sight of the vehicle in front of you. So, there could have been someone stalled down at the bottom of this curve, nighttime, fog, whatever, if you didn’t see them it was definitely an issue,” said Zimmer.
In the late 80’s a county bridge over the interstate at the Crawford site was found to have sunk six feet into the ground since it was built. But, in 2004 it had sunk too much and KDOT finally tore it down. Crews also filled in 12 more feet at the Crawford site and five at Witt for a total cost of $2.3 million.
Of the three sinkholes along Interstate 70, the Crawford site is by far the most noticeable. Engineers tell KSN ever since they took out the old bridge over the interstate this hole is actually starting to stabilize.
“Eastbound lanes have gone done to only about two inches a year,” said Croxton.
MAP – Crawford Sinkhole west of Russell
But, for some who drive over the area, like Dale Chrisler, who is a former oilman, is worried about the stability of the road.
“Very definitely, I have a granddaughter that crosses it twice a day,” said Chrisler.
His big concern is a sudden collapse of the interstate. It’s a concern that’s been brought up before, even Russell County Administrator John Fletcher has heard it.
“It’s always been talk of the county, talk of the residents around here, that someday a car may drive off down there and never come back up but it’s kind of a running joke,” said Fletcher.
But, KDOT Geologist Neil Croxton says these type of sinkholes don’t cave in, they slowly sink.
“We’re confident there’s not a threat of collapse. All of the times we have drilled and done seismic reflection, we have never found any large voids beneath the highway and we’ve never found any voids close to the surface,” said Croxton.
Croxton says they know this, because of their constant monitoring.
“Our survey people go out twice a year, every six months,” said Croxton.
“The whole area, for hundreds of feet is slowly settling and our highway just happens to be close to there,” said KDOT Regional Geologist Neil Croxton.
So, why keep fixing a problem roadway, when you could just build a new one around the sinkholes? KDOT officials say it’s not that easy.
“It would be very expensive. This is the smartest way to use our money. If we thought there was any danger to the traveling public, we would consider it, but we don’t think there is,” said Croxton.
So, when will the sinking stop you might ask? Probably never which means a costly mistake from more than 50 years ago will keep the state plugging the holes with tax payer dollars.
Geologists also point out, since there are so many abandoned oil wells in the area, finding a way to reroute I-70 around all of them would be very difficult.
- KGS: Gorham Oil Field Environmental Effects (includes details of sinkholes)
- KGS: Land Subsidence, Salt Dissolution (Oil & Gas operations)
- KDHE: I-70 Sinkhold Report (1985)