As part of the biomass conversion works, four storage domes were constructed at the power station, each being around 50m tall. Two stairs were required to provide alternative means of escape from the tops of the domes in the event that the main routes were not usable. Roscoe were responsible for the structural design of the escape stairs and the horizontal gantries that linked the heads of the stairs and the tops of the domes.

Detailed analysis of the differential movements between the domes, access gantries and stair towers was essential so that suitable allowances could be made in the design of various pinned and sliding connections between the elements. This task was complicated by the fact that the domes and their foundations would settle by up to 100mm when fully filled with biomass. A steel-framed solution was developed, with braces back to the concrete dome and a reinforced raft foundation.