Stuart Haywood says: Maurice Cass is quite right, the lagoons were cooling ponds. When I started working at Clay Mills in 1966 all 4 beam engines were still operating and pumping sewage up to the Etwall Farm, where the men we called water runners would dig small channels in the ploughed fields to distribute the sewage.
The white roofed building (A) in the top left of the picture is the lime sheds where lime came in from a spur off the main line railway prior to being transferred into narrow gauge trucks in the lime shed before being added to the raw sewage. This was because the sewage was so acidic that lime had to be added to reduce the generation of hydrogen sulphide prior to pumping.
The building immediately in front of the lime shed housed the screening plant (B) and the storm overflow pump.
The double roof building directly opposite the chimney is the workshop building (C) where all the lathes and drilling machines etc were belt driven served off a main drive shaft driven by an auxiliary steam machine in the corner of the fist workshop.
Adjacent to the workshops was the electricity generating room (D) were a steam driven turbine produce all the electricity for the plant.