One of the earliest phases of the archaeological work at T5 was the recording and interpretation of the disused sludge works at Perry Oaks. Built in the 1930’s the development of the plant is testament to the unprecedented population growth seen in the late 20th century.
When the plant was constructed in 1934 it was the equal of any of the most advanced plants found in Germany and the USA. By the time of its demolition in 2002 the plant had undergone a series of changes reflecting the development of waste treatment techniques.
The early circular concrete tanks were supplemented in 1952 with large rectangular tanks and later by a series of lagoons. The introduction of centrifuges in the late 1990’s eventually made such features redundant.
In 1965 the manual process of emptying the 72 acre drying beds was mechanised by the installation of mobile shovels and a traveling elevator.
The site also saw changes in the way that sludge was transported. In 1937 a portable 2ft gauge railway was in use on the beds. Dried sewage “cake” was, until 1940, dumped on site but the shortages during WWII created a demand for the material as an agricultural fertilizer. By the 1960s a special dried sludge storage area had been constructed. This was augmented by the installation of a conveyor system in 1965 but again both were made obsolete by the introduction of centrifuges able to discharge directly into parked trailer units.