Downtown Orange sits on older alluvial fans with stiff clays and sands, while newer developments near the Santa Ana River encounter loose, saturated deposits. That difference in soil behavior is exactly where the Flat Dilatometer Test (DMT) provides critical data. Unlike routine boreholes, DMT measures the horizontal stress index and dilatometer modulus directly. These values tell us how the ground will respond under load. For projects in Orange, especially near the river corridor, relying only on SPT blow counts can miss important lateral stress changes. Before designing foundations or retaining walls, we pair DMT with a SPT to cross-check soil strength, or use a CPT where continuous profiles are needed.
The dilatometer measures in-situ lateral stress directly — data that SPT and lab tests cannot provide reliably in stiff clays or sands.
