 Although Bateman does not appear to have been involved during the actual construction, his specification for building the dam has been preserved by James Cropper of Burneside Paper Mill.It specifies that the clay core was to be built up in layers, each thick, and that complete layers should be finished before work started on the next layer.The clay was to be soaked for 12 hours, and then cut into blocks, which were to be worked into the layer below by treading it.