Blenheim sits on the deep alluvial gravels of the Wairau Plain, where groundwater often appears less than two metres below the surface. The Wairau Aquifer feeds these coarse, permeable deposits, making dewatering a central challenge for any cut deeper than a single basement level. Our design work begins with a clear picture of the soil profile, and we frequently run CPT tests to map the gravel-to-silt transitions before selecting a shoring strategy, and in-situ permeability testing to size the dewatering system accurately.
On the Wairau Plain, controlling groundwater is the single biggest factor in keeping a deep excavation stable and on programme.
