Leander sits on the eastern margin of the Edwards Plateau, west of I-35, and the ground varies more across this city than almost anywhere else we work.
In the western communities, Travisso, Crystal Falls and Bar W Ranch, the terrain is clearly Hill Country: dissected, rocky, thin soil over limestone. On the eastern side toward US-183 and Ronald Reagan Boulevard it flattens out and the soils get deeper. A quote based on a Leander average would be wrong for both.
Because so much of the city is new, the more common problem is not the native ground at all. It is engineered fill and utility trenches. The house pad in a new subdivision is placed under inspection with density testing. The driveway, sidewalk and patio very often are not, and they sit over trench backfill and lot grading spoil.
That structural discontinuity is exactly why we get calls about a five-year-old house where the slab is fine and the driveway has dropped. Sand-bedded sewer lines act as underground water conduits, and documented Texas cases show one to two inches of differential movement inside three years.