The Honeymoon and East Kalkaroo sedimentary uranium deposits, located approximately 400 km north-east of Adelaide and 75 km north-west of Broken Hill, are natural concentrations of uranium minerals occurring in the Tertiary age Yarramba Palaeochannel, one of several similar palaeochannels developed between the Olary Ranges and Lake Frome in far eastern SA. Current resources at Honeymoon and East Kalkaroo total nearly 7900 t U3O8 equivalent, and there is potential to significantly increase this figure with further resource delineation. Goulds Dam deposit, which lies 80 km north-west of Honeymoon, has formed in the Billeroo Palaeochannel, and a resource potential of 17 600 t U3O8 equivalent has been delineated. At Honeymoon and East Kalkaroo, uranium mineralisation occurs at a depth of 100-120 m, predominantly within 'basal sand' of the Tertiary Eyre Formation on the outside margin of a major bend in the Yarramba Palaeochannel. The 'basal sand' is the lowest of three sand members in this formation, all of which are separated by clay layers. The mineralisation occurs within a coarse-grained pyritic sand bed, located within the palaeochannel fill where the 'basal sand' member pinches out between overlying clay interbeds and the Yarramba palaeovalley slope. The 'basal sand' mineralisation extends for 4000 m along the palaeochannel margin, is up to 400 m wide, and averages 4.3 m in thickness. The characteristics displayed by the Honeymoon orebody are typical of the well-developed, planar lower limb of a roll-front uranium deposit, as typically formed within an extensive aquifer sand at a reduction-oxidation boundary. Uranium is present primarily as coffinite, with quartz and kaolinite as the major gangue minerals. Mining lease titleholder Southern Cross Resources Australia Pty Ltd presently proposes to establish a commercial in situ leach mining operation based only on the Honeymoon and East Kalkaroo deposits. This will be capable of producing 1000 t/year of U3O8 equivalent as uranium peroxide (UO4.2H2O) for export and use in the electricity generation industry. This article discusses the technical aspects and results from field trials at Honeymoon of the in situ leach process, and describes the hydrogeological setting and predicted safe groundwater relationships between the target Tertiary aquifer and the adjacent Great Artesian Basin aquifers. Numerous investigations, surveys and studies have been undertaken since the discovery of ore-grade uranium at Honeymoon, which have confirmed the feasibility of the present development proposal, and contributed to the preparation of an Environmental Impact Statement (EIS). These include the field leach trial and demonstration plant, and geological and geophysical, environmental impact, hydrological, anthropological, radon and radiometric, socio-economic, flora, fauna, landform and soil studies. An EIS for commercial development of the Honeymoon Uranium Project was submitted to the SA Government on 7 June 2000. This initiated an eight-week public consultation period which ended on 2 August. Southern Cross Resources is now assessing the EIS submissions, and a response document will be prepared for State and Commonwealth assessment. Development of the project will result in significant economic benefits at regional, State and national levels. The annual contribution to Real GDP is estimated to be $20 million at State level, with a further $10 million in the rest of Australia. Direct and indirect employment generated by the project is estimated at 200 jobs. The project will benefit regional areas such as Broken Hill through the location of a permanent workforce, opportunities for employment and provision of contract services, upgrade of facilities such as the Mulyungarie Road, maintenance of the airstrip, and improved communications for first aid and emergency assistance.