Monument record 0058301000 - Filter Beds Spinney, Ascott

Archaeological survey of National Trust land in 1989 at Ascott records the surviving remains of the late 19th century estate sewage treatment works which was in use until the early 1980s. The small treatment house survives along with threee filter or settling tanks, a pump and winding gear connected to two circular tanks. The surviving fittings include installations by Thomas Crapper and by Farmer & Sons of Salford. See report for further information, sketch plan and photos (B6).

A very late 19th century and 20th century sewage works is visible on historic aerial photographs, documentary evidence and remote sensing data and was mapped as part of the Aylesbury Vale Aerial Investigation and Mapping project (EBC18604). Contained entirely within an unnamed spinney about 530 metres SE of Ascott House and centred at SP 89636 22426, the main mapped feature is an irregularly shaped earthwork ditch up to 29 metres W-E and 60 metres N-S, which is accessed by a 46 metres long curving track from the N. The area of the sewage works is shown as agricultural fields on the 1st edition OS map dated 1880. However, by the 1899 dated OS 2nd Edition map, a kidney-shaped unnamed spinney has been established that remains extant in 2022 and the sewage works are marked as an area of within it. The OS map shows an area of earthworks in which are the rectangular sewage works tanks. These features remain marked on the 1925 dated 3rd Edition OS map. On aerial photographs taken in 1944, the woodland is visible but none of the marked features are visible under the tree canopy. Not recorded on the OS mapping, but visible on remote sensing data, is a circular structure, possibly a settling tank, some 55 metres to the W of the recorded sewage works and centred at SP 89586 22445. With a 1.8 metres wide ‘wall’, it encloses an internal area about 11 metres in diameter. As it does not feature on recorded OS maps, it is likely that this is a 20th century addition to the sewage works that remain marked within the woodland on modern OS maps (7-11).