An investigation has been carried out at a possible site for the proposed Northern Power Station. Its purpose has been to provide data for an Environmental Impact Statement. The work has involved geological mapping with drilling and sampling, seismic refraction traverses and a vegetation survey. It is concluded that: • The site has liquefaction potential under seismic shock according to internationally accepted criteria. However records indicate that the area is subject to seismic activity of a relatively low level. • Suitable foundations exist over all of the site for support of a large structure. However special design considerations will be necessary through areas underlain by weak materials potentially subject to liquefaction. • Groundwater beneath the site is saline (range 19000 mg/l to 166,000 mg/l Total Dissolved Solids) and prospects for fresher water supplies near the site are poor. Geological formations beneath the site are generally of low permeability, and possible contamination of groundwater by saline waste water is considered to be unimportant. Natural discharge of extremely saline groundwater into Spencer Gulf may be increased, with possibly harmful effects to vegetation, but the current method of ash disposal as a slurry. • Apart from adequate supplies of fill, no quantities of suitable construction material occur naturally on the site. Supplies of coarse and fine aggregates and rail ballast could be obtained from local suppliers. Some furnace ash on the site may be suitable for concrete aggregate and road base material. Dune sands on the site are sensitive to wind erosion, and any interference with them would require careful rehabilitation afterwards. • The vegetation is in no way unique, but as much as possible of the mangrove, samphire swamp and coastal dune vegetation should be preserved. Any further filling should be taken from the existing burrow pit area, not from the coastal dunes for this reason. The coastal dune should be protected by a stock proof fence along its whole length to help dune stabilisation and reduce erosion by deflation. Acquisition of the land by an appropriate authority is recommended to ensure its preservation.