Preliminary geological report on two off-creek pumped storage damsites for the Coffs Harbour water supply

Abstract

Geological assessments of two possible sites, one near Karangi the other near Red Hill, were carried out to evaluate their potential for the construction of a 25 metre high off-creek pumped storage dam. Assessment of the foundation rocks was largely made from regional considerations. The bedrock consists of argillaceous sediments, with some coarser grained material, which exhibit a regional foliation. These rocks belong to the Carboniferous Brookiana Formation and the Permo-Carboniferous Coramba Beds. Thick to moderately thick soil cover is devel oped from these rocks, a lot of which is suitable for use as fill material. Sources of hard rock have been noted. Minor leakage problems which could occur may be readily overcome0 A third site which may warrant consideration has been noted.