Dene Hole at Sheldwich Lees
By Mike Clinch
Members of Kent Underground Research Group, one of the societies affiliated to the KAS, went to the Sheldwich Lees estate to reopen and survey a denehole. This particular denehole was first exposed some years ago whilst the field was being ploughed. The first problem was to find it. We had a digger and the man who originally discovered it. As you can see from the photo, there are few distinguishing marks on the field (Fig 1).
However, by excavating a trench and checking the soil discolouration we were able to locate the top of the shaft. A little digging exposed the steel crash barriers that had been used to cover the shaft (Fig 2). These were removed and an air test was carried out. A caving ladder was lowered so that two members of the team could go down to carry out the necessary safety checks. Following their report an aluminium ladder was fixed in position. The denehole was some 37 feet deep with a large spoil heap at the bottom (Fig 3). Those on the ladder were attached to a lifeline both on the way down and on the way up. The shaft intersected a passage, the north leg of which was fairly short, but the southern end had two side passages (Fig 4).
Air testing is usually carried out by lowering a candle lantern or a miner’s lamp. If the flame is extinguished it indicates that oxygen levels are low and carbon dioxide levels will be high. If the air quality is poor then we would normally pump air down the shaft and retest. Commercial oxygen meters are available but their calibration needs to be rechecked on a regular basis. The use of a flame is accurate, safe and cheap. There were very pronounced markings in the chambers indicating flooding at some time in the past. In view of the elevation of the site above the water table this is surprising and could be the result of heavy storms.
Back up to the surface and daylight. The denehole was then capped and covered with earth.
Exploration of underground sites and features can be both hazardous and dangerous if proper precautions are not observed. Kent Underground Research Group is well practiced in working underground and has the necessary experience, expertise and equipment to work safely. The group numbers amongst its members archaeologists, engineers, miners and rope access workers. We have in the past excavated mines, World War II bunkers, wells, icehouses, cathedral drains, secret passages and many other features. All these have been surveyed and written up. If you feel we can be of help on a dig, or to investigate that mysterious depression in the back garden, we can be contacted through our website www.kurg.org.uk or mike@mikeclinch.co.uk.