In January 1990, contractors working on the construction of new warehousing on the site of the old Tunnel Cement Works at West Thurrock, Essex, broke into chalk caverns adjacent to the site (NGR TQ 575 780).
The caverns were excavated into the side of the huge chalk pit which served the cement works and ran under a band of chalk which was left to support some of the works buildings. Subsequent to the closure of the works, the buildings were demolished and the bottom of the old quarry filled in to a depth of 2m or more. Excavations for the footings for new development in the pit reopened the caves.
The caverns are entered by a narrow walking height passage which leads to two large caverns 3m square connected by cross passages. All the passages are in unlined chalk and some roof collapse has occurred in the large caverns. The exact purpose of the caverns is unclear but old plans of the cement works describe them as an "air bottle store". They were probably excavated some time between the wars, along with a number of other drainage tunnels below the quarry floor which are not now accessible.
The caverns are to be grouted up since they lie below the road widening of the A282 which is being undertaken in connection with the new Dartford Bridge.