The Upper South-East Dryland Salinity and Flood Management Plan proposals aim to address the worsening salinisation problems now clearly visible in the area. This report provides feasibility and preliminary project design data to the EWS engineers who are preparing cost estimates for the project. It refers specifically to the excavation properties and side wall designs of both the proposed groundwater interception drains on the interdunal flats, where these may be of up to 5 metres depth, and the exit drain crossing points through the ridges, where excavation depths may be up to 30 metres. Investigative field work comprised excavation of 13 pits up to 5 metres deep, and drilling of seven cored holes to between 9 and 30 metres depth. Stratigraphic units intersected in the pits, the sites of which were confined to the interdunal flats, include fine-grained aeolian quartz sands of the Molineaux Sand, and the extremely variable ephemeral lacustrine sediments of the Padthaway Formation. Core drilling, sited on the dune ridges, intersected variably cemented bioclastic sands and sandstones of the Bridgewater Formation. The pits showed that the textures of the Padthaway Formation sands, sandy clays and clays have been altered by calcrete formation within the top 2 to 3 metres. The resulting substance strengths which would be encountered during construction of the groundwater drains would vary from soil to strong rock. In the northern section of the interdunal flats the predominant lithology is sand, while in the central and southern sections the sediments are more cohesive. While steep side walls to the proposed drains are considered feasible in the south and central areas, the sands in the north if cut steeply will require construction of much wider drain profiles, since there the walls are likely to collapse to form stable long term slopes of low angles. Where the drains pass through the high dunes of the Bridgewater Formation deeper channelways will be needed. Their walls will need to be benched, but the observed dune slope stability would appear to permit the use of steeper than expected overall wall slope angles. This design factor may aid in reducing the exposure of the bench walls to wind and water erosion, a problem recognised locally in newly excavated road cuttings.