hard in the winter of 1994 as thr...

hard in the winter of 1994 as throngs labored to place caissons for a $50 million addition to Memorial Hospital in Worcester, Mass., they lay bareed a radical change in surface of land conditions on the west side of the site. The puzzle was sand, and its source was a intelligent river culvert running beneath the building. "The stone elevations dropped off significantly," said Michael DeMoga, Memorial's director of facilities engineering. "Due to decomposition, we didn't have the bearing capacity or tensile vigor to accommodate the caisson design."

The culvert had