26 DECEMBER 2021 WorldWide Drilling Resource ® RENEW - SUBSCRIBE NOW! Drilling to Explore Hideaway Hills Sinkhole Adapted from Information by Fox Rothschild and Paha Sapa Grotto In April 2020, a large sinkhole caused the ground to collapse in a neighborhood called Hideaway Hills in South Dakota. Due to this event, several households had to evacuate the area. Many homeowners remain unable to return to their homes, while property owners throughout the neighborhood have been unable to sell due to a sharp decrease in property values. South Dakota historically operated gypsum mines throughout the region and still owns the subsurface and mineral rights. The state removed approximately 8619 tons of gypsum from the old mine under Hideaway Hills. According to records, over 275,000 tons of soil were disturbed or removed in Hideaway Hills before it was sold to land developers. Based on tonnage removed from underground, geologists estimate the old mine extends substantially beyond the sinkhole evacuation zone and is at least twice the size of the area that can be accessed from the sinkhole. Recent geophysical studies indicate a potential risk for sinkholes in a broad region surrounding Hideaway Hills, possibly including a stretch of Interstate 90. Data from soil-resistivity studies suggest unstable mines extend to the north, east, and south of the affected neighborhood. Work performed by the company Western Engineers & Geologists along with others concluded that flooded voids exist under a portion of Interstate 90. A separate analysis by Montana Technological University using electrical resistivity tomography provided more data about the voids. Separate soil-resistivity studies reached similar conclusions about the extent of gypsum mining that took place in this region of South Dakota, dating back to the early 1900s. Drilling operations recently began at dozens of sites in and around the Hideaway Hills neighborhood in the most extensive and definitive subsurface testing to date to determine the extent of danger caused by improper reclamation and maintenance of underground mines. A series of sites will be drilled in two phases to a depth of up to 150 feet. Core samples will provide definitive proof of the extent of underground voids, as well as the integrity of underground mines, pit mines, and strip mines. Editor’s Note: In between our print issues, the WWDR Team prepares an electronic newsletter called E-News Flash by WorldWide Drilling Resource ® . This newsletter is filled with articles not included in our print issue. Based on readership, this was the most popular article of the month. Get in on the action and subscribe today at: www.worldwidedrillingresource.com C&G The cave investigation below Hideaway Hills made national headlines when cavers discovered a classic car wedged in a tight spot near the roof of the mine. Photos courtesy of Paha Sapa Grotto. Working with emergency management officials, cavers initially entered the sinkhole to access the void at the bottom. Expecting to find a gypsum cave, they soon realized the sinkhole was a collapse into an abandoned mine. Over the course of one evening, six cavers mapped the extent of the mine creating imagery, overlay, and map data for county officials. (No Winner) n r Time for a Little Fun! October Puzzle Solution: Win a prize! Send completed puzzle to: WWDR PO Box 660 Bonifay, FL 32425 fax: 850-547-0329 or e-mail: michele@ worldwidedrillingresource.com PIPE RIPE RICE RACE RACK SHOW SHOT SOOT BOOT BOAT KILT HILT HINT HUNT HUNG MAGENTA ________ ________ WATCHERS ________ ________ PRODUCTS ________ ________ MINUTES ________ ________ INSERTED ________ ________ Rearrange the letters in each word to form two new words.