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[ Northwich_Vision ] [Stabilising_the_Northwich_Salt_Mines]
[Winnington/Wallerscote Urban
Village]
Potentially one of the
most far reaching changes to affect the area will be the regeneration project
known as Northwich Vision. This will see a dramatic rebuilding and development
programme lasting many years to revitalise the centre of the town, provide new
housing and increase business and leisure facilities.
Northwich Vision has
its own website that you can access from our Links page or by clicking their
logo below.
Anybody who has
bought a house in the Northwich area will be familiar with the legacy of the
salt industry that requires searches for subsidence risk resulting from
mining and brine extraction going back hundreds of years. The timber frame
with brick infill design of many Northwich buildings is due to a need for
them to withstand subsidence. They could be jacked up and levelled if the
ground dropped under them.
However, did
you know that Northwich stands over two very large and two smaller salt
mines, and that there is a high probability that they will collapse by the
year 2020 leading to subsidence of up to three metres in large parts of the
town?
The four 19th
century mines – Barons Quay, Witton Bank, Pennys Lane and Neumanns –
extracted salt from a layer 40 metres below ground. The salt was mined by
hand and 8 metre square pillars were left to support the roof. When the
mines closed it was realised that water seepage into the mines could
dissolve the pillars and so in 1920 the mines were flooded with brine. This
has served, to some extent, to protect the pillars and to provide
hydrostatic support. Modern understanding has established that 8 metres was
insufficient and the current working mine at Winsford has 25 metre pillars.
The problem
came to a head in 1988 when a developer drilled test boreholes before
committing to a project in the town. He discovered that the salt pillars
were being eroded and would eventually fail. Needless to say, he decided not
to go ahead!
This led to a
planning moratorium being imposed in 1994 and the start of a long process to
find a solution and the necessary funding to implement it. In 2002, after a
change to an Act of Parliament (previous legislation only allowed funding
for coal mines) the necessary finance became available from central
government and a project commenced.
The plan is to
fill the mines with a grout made from 97% Pulverised Fuel Ash (PFA), 2.5%
concrete and 0.5% salt – the exact mix will be fine tuned to achieve maximum
residual strength whilst at the same time minimising cost and allowing the
grout to flow through pipes into the mines. The grout will displace the
brine, which will be recovered.
The PFA will be
brought by rail from the Drax power station to a purpose built mixing plant
that has been constructed on the Brunner Mond site at Winnington. New
railway sidings have had to be laid in order to accommodate the trains. The
recovered brine will be pumped into a lagoon on the same site in order to
allow any solids to settle out and then sent by train to British Salt at
Middlewich for processing.
In September
the project began to make trial mixes in order to refine the mix quantities.
During October the mineshafts will be located, and work will commence to
plug these to prevent the grout escaping. When the mines closed the shafts
were filled, but there are no records of how this was done or of their exact
location. December will see the start of pumping trials.
In order to
connect the mixing plant and the mines five pipes have been laid – three
steel ones to deliver the grout and two plastic to return the brine (these
can be clearly seen running along the verges of Leicester Street). These
five pipes run through a larger 2 foot diameter pipe from near the Victoria
Hospital and under the Weaver; a distance of 500 metres. This pipe was
installed using an underground directional drill to avoid having to disrupt
the town with major excavations.
The
stabilisation work will start in January 2005 and continue until October
2007 during which time approximately one million tonnes of grout will have
been mixed and pumped. Pumping will take place for 12 hours a day.
The Council
have carried out a full building survey before work commenced so that any
changes can be properly assessed as the work continues. Once completed,
monitoring will continue for 10 years. The cost of the project at today’s
prices will be £32.5 million.
The Council
sees a redevelopment of Northwich as a leisure location following on from
the project - once developers feel they are on solid ground! This plan is termed
the 'Vision for Northwich' and currently
extends over a fifteen year period with better use of the riverside being
made together with 20,000 additional sq ft of retail space, 800 dwellings, a
hotel and cultural centre, multi-storey car parks, new road infrastructure
and even a new bridge over the river as an extension of Leicester Street. It
is hoped to generate an additional 500 jobs in the town.
Colin Perkins (October 2004)
The information for this article was derived from a
presentation given by David Billington (Project Manager for VRBC) at a
meeting of the Weaverham Trust on Wednesday 13th October 2004.
This
proposed development is for up to 1200 houses together with shops, a primary
school, health centre, employment uses, community facilities and open spaces on
a brownfield site comprising over 56 hectares at Winnington. The industrial land
is currently owned by Brunner Mond and has been disused for some years. The
proposal has been submitted by the Winnington Urban Village Consortium which
comprises Brunner Mond, Taylor Woodrow, Barratt Homes and Morris Homes.
The
original proposals to develop the site were put forward in 2001 but rejected by
VRBC due to a number of concerns. A subsequent resubmission, following
discussions with the Council, was rejected by the Planning Committee but that
decision was overruled by the Full Council in December 2003. The new proposals
are now said to be in accord with VRBC's 'Vision for Northwich' as discussed in
the article on the salt mines.
Due to
the scale of the proposed development the application was "called in" by the
First Secretary of State and a Public Inquiry was held in June 2004.
We
have been informed by Mike Hall, MP for Weaver Vale, that the public inquiry decision
was to reject the proposed development - the Inspector recommended rejection of
the application for two main reasons:-
-
The current housing supply in Vale Royal made a development of this size
"premature" until the Revised Local Plan (currently on deposit) is
agreed.
-
There was insufficient affordable housing included within the plans.
The
Inspector did not feel that traffic considerations warranted refusal.
The
Northwich Guardian has reported that the consortium plans to submit a revised
plan once the revised Local Plan is finalised.
Update
April 2006 - Following the Public Inquiry into the Revised Local Plan this
project will now go ahead.
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