Calvert Trust Culvert Clearance - Updated 3rd July

This news report was updated on July 3rd. For more photos taken at the work site Click HERE.

Clearance work at Wistlandpound carried out during September 2019 revealed that the cause of the wet area in the adjacent field occupied by the Calvert Trust was the inlet to the 18inch culvert under the railway embankment was buried and thus blocked. This was resulting in flooding of the field with the water percolating through the embankment over a 50m length.

Fig 1. Taken in Sept 2019 during the Working Weekend.

Covid obviously precluded any work last year to clear the culvert, but arrangements were made with South West Water and the Calvert Trust for access the field to clear the culvert and at the same time erect the permanent fence to what will be the new railway boundary there.

Aerial image of planned work.

The work was carried out over 3 days last week by various volunteers including those from the regular Thursday Gang with Martyn Budd driving the railway's excavator. John Rice one of Construction & Design's team of civil engineers oversaw the excavation of the culvert and new ditches.

Fig 2. Clearing the holes for the new posts with the Auger.

The existing concrete fence posts which only had 3 holes and were not suitable for the railway’s wire and netting fence, had to be extracted and replaced with 8 hole Southern Railway Concrete Posts. Once the old posts were extracted and the holes cleaned out with the auger attached to the excavator, the new posts were soon installed.

Figs. 3-5. The gang then followed up with the wire and attached the netting. On this length our normal Sheep netting was replaced at the request of the Calvert Trust with special Pony netting which has a smaller mesh to prevent the horses getting their feet caught.

Fig 6. The Culvert was expected to be buried about 1-2m below the current ground level. As the stream through the culvert emptied into the reservoir, straw bales were placed over the downstream outlet to catch any silt that would be disturbed excavating the inlet.

Figs 7-10. The culvert inlet was located around 1.5m below ground level and the entrance to the pipe was partially blocked. The long-handed Devon shovel soon had that cleared though. Ditches parallel to the railway fence were dug to direct the water draining of the field trough the culvert once more.

Fig 11. The view over the tracked to the reservoir.

Figs 12-14. A new fence has been erected by the Thursday Gang on the field side of the ditch with a gateway and sufficient clearance to allow access for future maintenance and to prevent damage by horses.

Further work will be needed to construct a new headwall and inlet sump. A CCTV survey of the pipe will also be required but at least now the culvert is flowing freely and the Calvert Trust field will drain properly, with the water flowing through the culvert and not through the railway embankment, this will enable that to dry out too. 

Text: Chris Duffell
Photos: Chris Duffell and Keith Lamprey

3rd July update. Yet more photos of the work undertaken are appended below, but without captions.

Our thanks to all involved in undertaking this work.