It may not have been hauled in -- they could have just used a bulldozer to sculpt out house sites without doing a thorough geological study. I'm sensing big-time lawsuits a'comin'
Bad construction and engineering.
Spot on.
Looking a couple of photos and this description it appears the slope of the hill is moving downward. Sounds like poor planning/etc in the developmental stages.
http://www.mysanantonio.com/news/local_news/Sinkhole_prompts_evacuation_on_Northwest_Side.html
Authorities evacuated about 80 homes in a Northwest Side neighborhood Sunday when ground caved in behind several houses, pushing earth down a 30-foot hill and into two retaining walls that cracked and threatened residences below.
No one was injured, and agencies acted quickly to address the endangered homes near West Hausman Road and Loop 1604.
Describing the collapse as a “slope failure,” authorities at a Sunday night meeting told residents from The Hills at Rivermist subdivision that in some areas the crevices grew to 12 to 15 feet deep and 6 to 8 feet wide. But they didn’t know the cause.
end snip
a home vid but very shaky shows the slope;
http://www.ustream.tv/recorded/4200736
A better view showing the area and homes: Note Oak Water that is where some of them were supposedly: Note retaining walls.