Garland’s geology shifts fast between the Blackland Prairie clays near Duck Creek and the sandier Eastern Cross Timbers soils around Rowlett Creek. A project off Broadway Boulevard deals with fat clay that swells on wetting. Meanwhile, a site three miles east hits loose silty sand that barely holds a trench wall. That contrast is exactly why an exploratory test pit saves money before excavation begins. We log the strata directly from the pit face, pull block samples for lab testing, and measure in-place density with the sand cone density method. It is a visual method. No extrapolation from a boring log. The test pit answers questions that SPT alone cannot resolve, especially when fill layers, old utilities, or buried organics are suspected within the top 10 feet.
A test pit shows what a drill rig misses: the real layering, the cracks, the roots, the old fill that never appeared on any map.
