With better equipment and engineering there's no excuse for these delays.
Think about the Thompson-Boling Arena delayed for years as they were stunned to find caverns in Knoxville next to the river.
Government is far too lenient with contractor and engineers not meeting completion goals. It's almost as if there's some sort of relationship between government and private contractors. If the contractor does not have the men and equipment to complete the job, then don't bid on it.!!!!
If a designer and/or engineer doesn't know that Knoxville's economy was almost entirely limestone based at one time, then is stunned to discover limestone caves under their $50 million (80s money) arena project, then they should be held accountable.
First, its actually up to the owner to provide the information for anything below grade, and any existing conditions. 95 times out of 100 the geo-tech engineer is hired directly by the owner, not the design professional or contractor. if there is a failure here, its on UT.
Secondly. even if they did the right things there is no way to catch all the problems. the way that type of geotech work happens is by drilling holes. those holes are about one foot in diameter. chances are pretty high you will miss some of those caverns. you aren't going to drill 1000 holes all over the place, its maybe 30.
third, the standards change as well. so even if the school and the geotech did everything correctly, the codes update every 3 years. and what may have been buildable 10 years ago, may no longer be allowed. especially as the design is getting heavier, so even if the codes didn't change, the stadium is getting bigger and heavier, that will have different impact on the process. so it may have been safe to put 5000lbs on a cavern, but not safe to put 10,000 lbs on the same cavern.
fourth, beyond the structural challenges, the under ground utilities have to navigate more and more things under ground. stadium is getting bigger, that requires more drainage, larger pipes may have to go lower than the existing areas where there were no issues before. most of those caverns are upside down bowl shaped, narrower at the top, wider at the bottom. maybe before at the shallower depths and smaller pipes the caverns weren't an issue, but with deeper bigger pipes they could have uncovered new problems that didn't exist before.
fifth, the contractor and design professional should have built in some agreed upon amount of "extra" into the design. but if the site conditions go beyond that extra, they can't cover it. the school shouldn't have an open ended contract, that is just an opening for highway robbery.
sixth, it could be totally on the city causing delays with inspections, or some bs permit process. you would assume the city and UT would have a great relationship, but they usually don't. and the city is very cautious to allow risks for its flagship college, young students, and important highly visible projects.
just food for thought. it could still be 100% a screw up, but it doesn't have to be. If the school wants promises on delivery they are going to have to provide 100% accurate info, and they are going to have to pay more than they typically would to get the quality that can/will guarantee delivery. you are talking probably 25% mark ups, at the least.