Escondido sits on a complex interface between granitic bedrock and alluvial deposits, with decomposed granite covering much of the northern valley floor. Depth to competent rock rarely exceeds 15 feet in hillside subdivisions, but groundwater can appear seasonally in the lower Escondido Creek drainage. An exploratory test pit lets you see these transitions directly. We open trenches up to 14 feet deep, log strata per ASTM D2487, and photograph every wall before backfilling starts. For projects near the Rincon del Diablo formation, we often pair the excavation with grain-size analysis to confirm the percentage of fines in weathered granite that standard borings might miss. The method is fast: most residential pits are completed, logged, and closed within a single working day.
A 10-foot test pit reveals more about soil structure than 30 feet of SPT split-spoon samples in the decomposed granite terrain of North County.
