While the Limecrest Quarry site was one of the top development prospects, Riverbank is pursuing other locations – especially at Wiscasset, Maine, which showed good geological results in early investigations.
The US company said poor geology below Limecrest Quarry was discovered at depth following initial drill tests. Its “Aquabank” standardised pumped storage system requires a grid of tunnels and caverns to be excavated at a depth of approximately 610m.
The underground complex would hold both the powerhouse and the lower reservoir of the closed loop circulation system. At Sparta, the upper reservoir was to be formed by the flooded quarry. Riverbank announced the project at the start of the year.
The standardised hydro concept would call for US$2B of private investment and take four years to build. Riverbank is supported by venture capital firm Blackrock.
The Wiscasset facility is planned to come into service in 2014, should further site investigation of the schist rock, known as the Cape Elizabeth Formation, also prove satisfactory.
