SAN ANTONIO — Construction crews moved dirt to shore up a group of houses precariously perched on a crumbling hill in San Antonio on Monday as engineers tried to determine why the land below was shifting, causing dozens of homes to evacuate.
Gaping crevices, some 15 feet deep, cut across several yards as dirt cascaded into a towering stone retaining wall that nearly split in half. Fences crumpled like accordions as crews packed dirt under one home and around its exterior after part of its foundation was exposed.
One soil expert said the cause of the landslide appeared to be the result of poor retaining wall design, and a city official said the nearly 1,000-foot-long wall was built without a permit.
No one has been injured, but about 80 homes were evacuated on Sunday after a resident in the northwest side subdivision reported that his backyard was sliding downhill.
By Monday afternoon, residents in about 55 of those homes were allowed to return after inspections and soil monitoring found them to be safe, said Valerie Dolenga, a spokeswoman for Pulte Homes Inc., the parent company of the neighborhood's builder, Centex Homes.
One neighbor who was among the first homebuyers in the subdivision said he was initially told no homes would be built on the crumbling ridge because it was too steep.
Romeo Peart, 32, said one retaining wall failed several years ago before the current one was built and homes were constructed above it.
"They can keep the view now," Peart said, shaking his head as heavy equipment stuffed dirt beneath an exposed foundation. "And they paid an extra $10,000 for those lots."
The near-vertical retaining wall likely failed under the weight of the area's clay soil that readily expands when drenched with heavy rain as it was last week, said Sazzad Bin-Shafique, an assistant engineering professor and soil expert at the University of Texas-San Antonio who went out to the site on Monday. Steep, tall retaining walls can hold up if built correctly, he said.
Roderick Sanchez, the city's planning and development director, said the builder built the retaining wall without a permit. The city was still waiting for verification that the wall was designed by a certified engineer and built to specifications, Sanchez said.