A common mistake we see in Orange California is assuming a single percolation rate applies across the whole site. The alluvial fan deposits here vary from sandy loam near the Santa Ana River to clayey layers closer to the Santiago Hills. Without a proper infiltration test using a double-ring infiltrometer, you risk designing a basin that either ponds water or never drains. We have seen projects where the client skipped field testing and ended up with a drywell that failed within six months. Before you finalize your stormwater plan, combine this test with a classification of soils to confirm the soil type matches the measured rate.
A single percolation hole is not enough. Orange California's alluvial soils demand multiple test locations to capture lateral variability in infiltration rate.
