Flooding timeline

<b>14 August 1967</b><br />
The southern approach cutting was acquired by Halifax Corporation for landfill purposes. <b>Mid-1970s</b><br />
The south portal, photographed by a Cambridge University scientist who was part of the tunnel-based team undertaking research into earth strains (1970-79). At this time, the leading edge of the floodwater typically extended 400 metres into the tunnel, past No.2 Shaft.<br />
<i>(David Young)</i> <b>Mid-1980s</b><br />
The infill had reached northwards to the aqueduct which spans the approach cutting, 160 metres from the tunnel portal. At this time, the leading edge of the floodwater typically extended 550 metres into the tunnel, midway between Nos.2 & 3 Shafts.<br />
<i>(Stephen Prior)</i> <b>May 1991</b><br />
Little difference is apparent in this view, with the leading edge of the floodwater extending to a point between Nos.2 & 3 Shafts.<br />
<i>(John Simmons)</i> <b>April 2007</b><br />
In 2006, the cutting was infilled to its current extent. Thereafter, the depth of water at the portal has generally varied between 7.5 metres (dry periods) and 11.5 metres (wet periods). In April 2007, the leading edge of the floodwater extended 750 metres into the tunnel, to a point north of No.3 Shaft.<br />
<i>(Forgotten Relics)</i> <b>October 2012</b><br />
In 2012, the landowner dewatered the tunnel after British Railways Board (Residuary) took legal action against him, claiming £5.2 million in damages. The action proved unsuccessful; however the dewatering did allow BRB(R) to undertake their first full inspection of the tunnel for many years.<br />
<i>(Forgotten Relics)</i> <b>March 2013</b><br />
Once the inspection had been completed, the tunnel was allowed to flood again. In March 2013, the leading edge of the floodwater extended to a point midway between Nos.3 & 4 Shafts.<br />
<i>(Forgotten Relics)</i> <b>July 2015</b><br />
In 2015, with a lease of land agreed between the landowner and the Secretary of State for Transport, Highways England dewatered the tunnel to allow the construction of a pumping station.<br />
<i>(Forgotten Relics)</i> <b>18 January 2016</b><br />
The design and construction of the pumping station was protracted and the cutting refilled with floodwater through the latter part of 2015. This photograph was taken after the water level had risen by about 1 metre in 16 hours (at a rate of 81 litres/sec), requiring the landowner's representative to rescue the contractor’s tower light.<br />
<i>(Forgotten Relics)</i> <b>April 2017</b><br />
The pumping station was commissioned in 2016. During construction - based on his own dewatering experience - the landowner advised Highways England’s contractor to install a 6-inch pump/pipework, rather than the intended 3-inch pump/pipework. His advice was ignored. As a result, the system was sometimes unable to cope with the volume of water entering the tunnel. On one such occasion, the leading edge of the floodwater extended 360 metres to No.2 Shaft.<br />
<i>(Forgotten Relics)</i> <b>23 September 2018</b><br />
The Secretary of State’s lease was forfeited in December 2017 due to Highways England’s failure to ever pay the £50 annual rent. The landowner allowed the pump to remain operational for nine months whilst the DfT/Highways England entered into negotiations about new arrangements. However they failed to do so and the pump was switched off in September 2018.<br />
<i>(Forgotten Relics)</i> <b>Early December 2018</b><br />
By this time, the depth of floodwater was within 1.5 metres of its typical maximum winter level.<br />
<i>(Forgotten Relics)</i> <b>Early January 2019</b><br />
The cutting had completely refilled.<br />
<i>(Forgotten Relics)</i> <b>27 September 2019</b><br />
Using their temporary pump, AMCO-Giffen had removed the floodwater to a point close to No.2 Shaft.<br />
<i>(Forgotten Relics)</i> <b>4 October 2019</b><br />
Six days of persistent heavy rain coupled with the switching-off of AMCO-Giffen’s temporary pump due to the threat dewatering was posing to water levels in Hole Bottom Beck resulted in the floodwater returning to its typical maximum winter level. The average rate of inflow over the six days was 78 litres/sec.<br />
<i>(Forgotten Relics)</i>

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Wednesday 27 May 2020