Look Inside That Big Pit By The Sioux Empire Fair Grounds I've driven by that big pit between I-29 and the W. H. Lyon Fairgrounds in Sioux Falls more times than I could count. But I've never seen what's inside. That “big hole” is the quarry operated by Concrete Materials. The quarry just off Madison Street has been in operation since the 1940s. From the top of the quarry at street level to the bottom of the North Hole is 240 feet. There is also a portion referred to as the 'South Hole' which has been mined since 1980. Parts of the south quarry are at a depth over 325 feet.