Gloucester Docks &
the Sharpness Canal

Still Ditch Culvert

Contractors preparing to install a storm water outfall from the Sainsbury’s construction site on 5 Dec 2008 were surprised to open up a 9ft diameter brick shaft close to the canal bank. Urgent research in the archives revealed that this was associated with a culvert that had once carried a stream and later a sewer under the canal. This page reports the findings of that research and what the contractors did to the shaft. (Photo D Viner)

Culvert
     The original culvert under the canal, about 110 yards south of the new High Orchard Bridge, was built in the 1790s for the southern branch of the Sudbrook known as the Still Ditch (or Tweenbrook) which drains what became the Linden Road area of Gloucester. There was another culvert for the northern branch of the Sudbrook on the line of High Orchard Bridge. The two branches joined on the west side of the canal and entered the River Severn just above the later Llanthony Weir. A report in 1801 records that the southern branch was carried under the canal by two 16 inch diameter cast-iron pipes and the northern branch by one such pipe. (OS maps; TNA RAIL 829/4 p255) 

Sewer
     During the second half of the nineteenth century, Gloucester expanded rapidly to the south, and there was growing concern about providing proper drains for the area. Thus in 1884-85, the existing culvert was incorporated into a new sewer to serve the South End Drainage District. The sewer followed the line of the stream from the one-mile milestone on the Bristol Road through what were then timber yards to the culvert under the canal, and then it took a new line direct to an outfall on the River Severn just below the recently constructed Llanthony Weir. The plans for the sewer show the two existing 16 inch pipes under the canal and new access shafts on each side. (Glos Arch GBR L10/1/3)

Redundant
     In the 1950s and 1960s, a major new sewerage system for Gloucester was constructed, including a pumping station and treatment works at Netheridge, and the sewer through the culvert became redundant. The vertical shafts were capped with concrete and forgotten - until contractors preparing to install a storm water outfall broke up the western cap and exposed the shaft again.

New Work
     The contractors found that the shaft had been filled with concrete up to the invert of the outlet pipe - which had also been plugged with concrete. They poured in some reclaimed hardcore and some more concrete to form a foundation for the chamber of the new storm water outfall that they had originally set out to build. In due course, the chamber itself was constructed on top of the foundation, and the picture shows the shuttering in place ready for pouring the concrete. The outfall was eventually completed in March 2008.