The great escape of the spring comes from Albert Reitz and his lawnmower, which barely outran the Great Black Hawk Sinkhole:
Albert Reitz was mowing his lawn after work on Monday when he felt it.
“I felt suction behind me and a little bit of movement under my feet. I looked behind me and I was only a foot away from” a sinkhole, he said Friday as movers were packing his home in Blackhawk.
“I didn’t even hear it go down, it just went down,” said the 56-year-old. I was “scared as hell.”
The sinkhole collapse at 5:30 p.m. that day broke water and sewer lines that further ate away at the earth, widening the hole in the Hideaway Hills subdivision to 40 by 50 feet [Arielle Zionts, “12 Blackhawk Families Displaced After Sinkhole Exposes Abandoned Gypsum Mine,” Rapid City Journal, 2020.05.02].
Perhaps sinkholes in this neighborhood are to be expected, since this housing development was built over an abandoned gypsum mine:
Meade County Emergency Manager Doug Huntrods… said there are indications of gypsum and substantial evidence of a former gypsum mining operation there in the early 1900s.
“We know that there has been mining in the Black Hawk area back in the 1920s, but it’s hard to know where the tunnels went. I’ve heard anecdotal information that there were tunnels in this area,” he said.
A search of current mining claims shows the Dakota Plaster Company Pit – U.S. Gypsum Company Blackhawk Operation – in Meade County near Interstate 90 at Black Hawk [Deb Holland, “Black Hawk Residents Evacuated Because of Sinkholes,” Black Hills Pioneer, 2020.04.30].
Gypsum is highly water soluble; having big manmade tunnels underground facilitating the flow and erosive power of water only deepens the sinkhole danger.
Spelunkers have found the caves below the sinkholes are big enough to have already swallowed up past junk from Black Hawk:
Christopher Pelczarski is a caver, and he’s seen a lot of underground passageways. But he’s never seen anything like the abandoned gypsum mine that was exposed by sinkholes this week in Black Hawk.
For one thing, he never expected to find a car down there.
“There was one place where there is actually literally a car coming out of a hole from the surface, an old car. It’s like a 1951 Ford,” Pelczarski said. “Yeah, it’s half sticking out of the ceiling, basically.”
He figures there used to be a scrapyard or garbage dump on the surface, and the car somehow sank down from there.
…The cavers mapped 2,300 linear feet of passages, Pelczarski said. There were additional tunnels they couldn’t access because they were flooded or collapsed. Some of the tunnels were big – 12 feet high and 40 feet wide.
The ceiling at one place in the mine was 30 feet above their heads, indicating a potentially thin surface above [Seth Tupper, “Caver Describes Exploration of Black Hawk Sinkholes and Mine,” SDPB, 2020.05.01].
Zionts has remarkable photos of the mine tunnels and the junk therein, which houses above may soon be joining:
Photos
6/x pic.twitter.com/AF2ThtNYoI
— Arielle Zionts (@Ajzionts) May 2, 2020
Zionts is also tracking down the developer, who is apparently harder to find than information about the old mine itself:
Meade County departments are collectively looking into the history of the subdivision to determine if the mine was ever disclosed to the county in the original proposal in 2002. After moving buildings since then, they have not been able to find those papers. According to the Meade County Equalization and Planning Office there are no answers as to who knew of the mine [staff, “Two Sinkholes in Black Hawk Led to Discovery of a Potential Gypsum Mine,” KNBN-TV, 2020.04.30].
The gypsum mine, built in 1911, is well-documented. Dakota Plaster Company supplied gypsum to the State Cement Plant just down the road in Rapid City:
At Black Hawk, the Dakota Plaster Company continued the output of plaster and building tile and an increased production was made over the previous year. This company has the contract for supplying the gypsum used at the State Cement Plant and the mine was in continuous operation. An average of 13 men is employed [Otto Ellerman, Thirty-Fifth Report of the State Mine Inspector of the State of South Dakota, 1926.04.03, p. 9].
The Dakota Plaster Company was owned by the United States Gypsum Company, held now by USG Corporation.
Black Hawk residents have taken pride in rejecting incorporation and taxation of their settlement and resisting government interference in where they build their houses. We’ll see how much government assistance Black Hawk residents now seek for the houses they built and bought on top of a cave-in-prone gypsum mine.
Yep, we know the first place these libertarian government haters will turn is to every government assistance, relief, and justice system they can. That, of course, will be closely followed by suits against those same entities when they are less to satisfied. Self sufficiency and “rugged individualism” will be as abandoned as that mine and is a political philosophy just as lacking in self-sustainable support of anyone relying upon it.
Great headline. Like Black Hawk, Meade County also resisted most forms of zoning and civil property rules.
This link from an area homeowner shows some effects from the mine. Apparently someone failed due diligence, and perhaps disclosure. This web link has maps and documents from the US Geological Survey, and general informative comments.
https://www.reddit.com/r/legaladvice/comments/gbhs9t/buyers_back_out_of_a_home_sale_due_to_possible/
Great link, John! That homeowner raises a huge point: these sinkholes will sink property values for everyone in the neighborhood.
That 2005 South Dakota Geological Survey map is great (see first comment in the Reddit post). It shows the gypsum mine exactly where mindat.org does, right under where Daisy Drive loops southwest of the I-90 exit. The mine was not forgotten; it was recorded on publicly available maps.
No strong zoning from the county either, John? Would there have been any kind of public geological inspection before the housing development was platted and permitted?
I moved to Black Hawk in 1984. Black Hawk is unincorporated. The area in question was the site of sewage lagoons for the Northdale subdivision. Northdale became a sanitary district and tied into Rapid City for wastewater treatment. A sanitary district has no authority over development or building codes. They are generally limited to wastewater and may be consolidated with a road district. The land was left vacant for several years.
The mine shown on the map was a relatively short term quarry for the cement plant and was strictly a surface/trench operation. The land was reclaimed and sat vacant for several years until it was developed as Hideaway Hills. It is part of the Northdale Sanitary District.
The “old timers” in Black Hawk would talk about the underground mine and gypsum mill that was located in the area of Daisy Drive. The mine was used for a community dump including old vehicles. The SDNG supposedly blew the entrance closed in the 1960s when I-90 was constructed. The cement plant is currently quarrying gypsum east of I-90 in the Black Hawk area. One of the early pits for this operation was adjacent to I-90 at westbound exit 52 and has moved east from there. Anecdotal comments from crews doing the exploration for the current mining and having access to some of the underground mine and reported the use as a garbage dump in the old underground mine. There appeared to be a second entrance to the underground mine on the hillside north of Box Elder Creek east of I-90. I believe this entrance has been closed as part of the current mining operation.
The development was approved by Meade County IAW the county ordinances and state law.
Freedom First!!! They say. Lawyer up!! They say. I say find a house mover and buy a new lot, that has ground under it, and move on. Buyer beware of the low tax and no regulations.
A couple of years ago, Tilford, South Dakota ( Freedom First) village, had a fire that killed the Sturgis fire chief. When the fire was going, before the propane tank exploded, the residents wanted the fire teams to just leave.
“Additionally, a Meade County sheriff’s deputy, Daniel Morgan, was airlifted to Regional Health Rapid City Hospital for treatment of smoke inhalation, Sheriff Ron Merwin said. Morgan was released and is recovering at home.
Merwin said deputies met strong initial resistance asking other nearby residents to evacuate their homes.
“It’s like everything else, nobody wanted to leave. We got called lots of things, expletives, until the fuel tank blew, then everyone wanted to leave,” Merwin said.”
Rapid City Journal 9/18/2018
These sinkhole residents thought they were getting a great deal with low taxes and no hassle living. Just chip in to the community pot and all will be well. Now everyone who lives in Black Hawk and the Piedmont Valley had better suck it up and understand that there is a price for not paying the price. Good luck to the sinkhole folks in trying to get money from the county. As Cory points out, that mine was in the public records and if you put a 30 year mortgage on something, you should do due diligence on your own.
Just wonderin’ Dept: is anyone at the state level worried about the integrity of I-90 ??
Maybe 25-30 years will need to pass before consequences materialize, but this disaster never should have been allowed to happen. We tend to get the govt we pay for.
Great background, WR! Do you know when the development was approved? The only approval it would have needed would have been from the Meade County Commission, right?
WR, the reclamation you refer to—what did that consist of? Simply filling the open trench with clay and topsoil? How would that address the giant caves underneath? Did that reclamation have to meet any standards for future development?
Exactly, Buckobear–makes a person think twice about that drive from RC to Sturgis/Deadwood/Spearfish/Wyoming.
Cory,
I cannot say for sure but the reclamation probably consisted of filling the trench in compacted layers. They should be stable. I doubt that the surface mining was anywhere near the caverns as the team that went into the mine found bore holes that had been plugged. You don’t want to take a chance of dropping men and equipment into the caverns. Somewhere there is probably a map of the underground mine. I suspect the surface mines picked areas that had not been previously mined and possibly seams too small to be considered feasible for the underground mine.
I-90 should be safe. The engineers were aware of the mine, probably collapsed any caverns and filled the finish grade.
Wow! This could get interestinger. Do keep us appraised please.
I know folks on West Elm. I used to drive up there all the time to work on environmental issues. The gypsum mine was pretty well known by the locals back then. What I remember goes along with what WR Old Guy is saying. As far as reclamation, I’m not sure it was necessarily done very well. I would like to see the as constructed drawings on that.
The underground mine probably did not have any reclamation done as it closed long before the EPA and other government agencies came into being. The Black Hills have a lot of abandoned mines that were never properly shut down and were open to anyone foolish enough to venture in. The USFS has closed many but there are still some out there.
I don’t think the reclaimed area of the surface mining will be a big problem. I don’t remember who the contractor was that did the work. The state and the cement plant should have the information on the reclamation process.
In addition to its history of gypsum pit mining, Black Hawk is in an area known to have naturally occurring sinkholes. From a 2001 USGS report by Jack Epstein: “Karstic collapse due to dissolution of gypsum and anhydrite is an active process in the northern Black Hills. Dissolution of gypsum in the Spearfish and Gypsum Spring has resulted in collapse and formation of many sinkholes in several areas that are presently undergoing development between Rapid City and Spearfish, SD (Rahn and Davis, 1996; Davis and Rahn, 1997).”
(https://water.usgs.gov/ogw/karst/kigconference/jbe_hydrologyhazards.htm)
Too bad…..54 Ford convertible….very collectible….
Gypsum is the correct/appropriate name for any dealer attempting to sell that Ford.
Wow! Has there been an Update to this story?
Yes: 120+ plaintiffs are suing 50+ defendants for $75+M.