An archaeological watching brief was undertaken during the deep excavation of a sizeable area at the Mansfield Bath Lane Sewage Works for new storage tanks. The south-east corner of the area, about 100m x 200m in size, was thought to cross the postulated line of a tail-race from the nearby 18th century Bath Mill, a building now in derelict condition. The brief suggested that the underground stone-built channel recorded in a watching brief undertaken in 1999 might be aligned further to the north and that the proposed deep excavation could overlap with it. There remained the possibility that the channel might show within the section of the new deep-excavation. After an intial visit to record site progress, a second visit in October was able to observe the excavated hole. The hole is about 5m deep and its eastern side is not as close to the river as the original plan showed. The remaining building and shallow tanks alongside it had been left but were to be removed eventually, but requiring an excavation of only 2m in depth. The 1999 watching brief recorded that the ground in this area, adjacent to the river, has been raised by up to 3m since the sweage plant was opened in 1912. The channel did not show in the deep excavation and it was also unlikely to be revealed in the intended shallower excavation. Because of this, and the greater likelihood of its course being outside the area of interest, it was decided that the watching brief be terminated.