They build on shifting soil, but to add to the stupidity, they put truckloads of dirt on top of that expansive soil. When the rains came, the slope failed. It's as simple as that. Centex didn't pay attention to the engineer nearly as much as they should have, and now, the only way to stop the hemorrhaging is to buy the homes back in The Hills of Rivermist. Check out the Express-News in San Antonio. Keyword RIVERMIST. It only gets worse the further you read. Like a crime novel, only TRUE.