At the invitation of Affinity Water’s project team, Nick Rogers and Nick Balmer visited the site on
Tuesday 14th of March.
Melissa Ahmet, Affinity Water Project Manager for the augmentation scheme, and other members
her team, explained that the borehole was currently 20 metres deep. It is intended to sink the well
40 metres below ground level. As the ground surface is about 54m AoD (above sea level) where the
borehole is being installed, it had been expected that there would be made ground, i.e. non-natural
deposits from human activity. This proved to be the case with bricks & old tip material. At about 4m
down the lower layers of the Melbourne Rock were penetrated.
The borehole rig is a Shell and Auger Rig which, while ideal for the purposes of installing the well, is
not ideal for recording Chalk, as the action of the cutting head and drilling fluid destroys the Chalk
Samples are being taken at 1 metre intervals, which we were shown, but the Chalk arisings were
pulverised into mush by the head, so it’s difficult to interpret the geology from them.
Image courtesy of : Samples from the borehole, courtesy of Affinity Water. A sample is taken at 1 metre intervals as the borehole
progresses. The shallowest sample is at the top left, with each sample from left to right getting deeper. The shell & auger
rig unfortunately pulverises the chalk, adding water to the chalk, which destroys the all important structure of the Chalk.
The borehole had passed through the Zig Zag Chalk, and was through the Tottenhoe Stone (the
aquifer, that outcrops at Radwell). Affinity hope to tap into this lowest aquifer. We expressed our
concern that the Tottenhoe Stone was their preferred source of water for the augmentation system.
With the Melbourn Rock Aquifer has been empty since April 2022, and the Tottenhoe Stone Aquifer
almost dry last Autumn, RevIvel do not believe that it will be sustainable to take augmentation water
from the Tottenhoe Stone during drought years. Drought years, are exactly those when the
augmentation scheme is most needed, and are precisely the same years when the aquifer will be at
its most over extracted.
We were pleased to see that Affinity Water will taking the borehole down a further 20 metres, to
approximately 16 m AoD. This will increase the chances of tapping into the West Melbury Marl, that is situated under the Tottenhoe Stone, and above the Upper Greensand.
There are very few existing boreholes that go deeper than the Tottenhoe Stone, because until very
recently there was always groundwater present in the aquifers above this level. It was not possible
to justify the expense of drilling any deeper.
There has only been one previous other drought of the intensity of 2022, in recent times, when the
water supplies from the chalk came very close to failing. This was in 1963-4, when three wells were
sunk at Radwell and Bygrave down to the Gault Clay. These wells did provide water, but were very
expensive to run, so the water authorities responsible at that time abandoned them as soon as the
Chalk aquifers refilled during 1965 and the following years.
With the huge expansion of demand in North Herts linked to population growth, the existing water
situation is currently at least, if not more serious than in the 1960’s.
Years of under investment in water infrastructure is coming home to bite the entire community.
RevIvel are pleased that Affinity Water have recognised that their over extraction, has destroyed the
upper reaches of the Ivel, and are taking steps to try to remedy the damage. We have been in
discussions with Affinity Water, the Environment Agency, NHDC, our MP and many elected members
of local government since February 2022, and have repeatedly pointed out the inadequacy of
Affinity Water’s proposals.
In September 2022, RevIvel laid on a demonstration, that reproduced the level of recharge
augumentation flows that Affinity Water intend this new project to deliver. The flows are throughly
inadequate, and as the demonstration showed the water delivered by the scheme will be soaked
away within 10 to 20m of the outlet.
Affinity Water had promised to deliver enhancement works to the Ivel Springs Nature Reserve
during the Winter of 2022. We had been informed that the tree work by Affinity Water would be
completed by 1 st March 2023, ahead of the earthworks. Regulations do not allow the felling of trees
within the bird nesting season. We asked Affinity Water’s Project Manager when they intend to
carry out the channel enhancements, and were told that they hope to start in the autumn of
Volunteers from Baldock Greenspaces have been working very hard to coppice or pollard many of
the existing trees in the Ivel Springs Nature Reserve in recent weeks. We welcome this effort, as the
regrowth from pollarded and coppiced trees will greatly increase the potential for nesting birds etc.
in the coming year.
While at the Anglian Water Sewage pumping station, we witnessed part of the final commissioning
of the new section of the pumped foul sewer which, the site supervisor told us, they hoped would be
completed by Friday 17 th March.The new main replaces the old section of pipe that has burst four
times in less than 2 years, sending thousands of gallons of raw sewage cascading into the riding
school and Ivel Springs reserve.RevIvel has been working behind the scenes to bring pressure to bear
on Anglian Water for the last two years, and are very pleased that Anglian Water have finally
competed the work.