Jen and I wrote a follow-up story today about the sinking neighborhood in San Antonio called the Hills of Rivermist:

The retaining wall that collapsed last week and jeopardized a neighborhood built by Centex Homes was built with less mortar than what engineering plans called for, according to city officials who inspected the wall Friday.

“Staff determined that the retaining wall was not built in accordance with the design provided by (the) design engineer,” Assistant City Manager T.C. Broadnax wrote in an e-mail to his boss, Sheryl Sculley, Mayor Julián Castro and the City Council.

“For example, the building plans for the wall show limestone mortared throughout the wall. Based on field observations of the failed portion of the wall, mortar was not installed according to the building plans.”

There are many different types of retaining walls. The one at Rivermist is called a gravity wall, which relies on a heavy mass of mortar and stones to remain stable. So if a contractor skimps on the mortar in the core of the wall, the wall becomes lighter and it can become unstable.

Here’s the city e-mail describing the lack of mortar inside the wall. The city also set up a new Web page that provides updates about Rivermist. Residents can also report concerns about retaining walls near their homes.