For our member event this month, we were pleased to visit the substantial Ho 4 tunnel complex above Grands Vaux Reservoir. Constructed by the Deutsche Asphalt Company using French, North African, and later Russian forced labourers during WW2, it sits nearly empty and unused today. The northern entrance is blocked by rockfall and vegetation however the southern entrance is open and leads to a Jersey Water storage yard.
Massive thanks are due to Jersey Water for not only granting access, but for opening up on a Saturday morning and spending several hours assisting us whilst our tour was underway.
A total of 70 Society members showed up for the visit, fifteen of which were new members signed up on the day. The sheer number of visitors walking around with torches made for some interesting photos! Handouts were provided with excerpts from Society publications and historic maps, and members were allowed to explore the entire site in self-guided groups.
Several of the connecting tunnels in the centre of the complex are blocked off by rock falls, described here in an excerpt from Jersey's German Tunnels:
On 28th April 1943, Sinel recorded that a premature explosion in a tunnel in Grands Vaux resulted in several casualties being taken to hospital, but this did not necessarily occur in Ho 4 as two other tunnels (Ho 10 and Ho 12) were being excavated simultaneously in Grands Vaux. However, a severe roof-fall occurred in Ho 4 and this penetrated right through to the surface with consequent interruption to agriculture in a field belonging to Augrès Farm, where a large pit suddenly appeared. This roof-fall is doubtless the reason for the blocked off gallery in the centre of the complex.
After being cleared of ammunition by the British Army in 1946, the tunnels were used for many years by Jersey Potato Canners. More interestingly, under the emergency planning provisions for dealing with the anticipated swine flu pandemic in 2010, Ho 4 would have been pressed into service as a mortuary.