Page 38 - Gi flipbook September 2018

IGEM NEWS | Young Persons Paper Competition 2018

geotextiles to hold it back, the dam
will be strategically broken and water FIGURE 3 Current state drawing of the River Mersey and erosion problems
will flow down this new route. All the
new channel material will be
stockpiled in order to be utilised on
the new 300m stretch of the TLHB.
The reconstruction of the TRHB will
start from the upstream section and
use large reach 20 tonne machinery
and large quarry rock. The direction of
the water's flow will start to be
pushed away from the TLHB.
The new banks will be built up with
locally sourced quarry defect rock,
individually chosen to fit the bank,
then the reclaimed material from the
inside bend will be utilised to backfill
on either side.
This will all be tied in by the use of
chestnut wood stakes, geotextiles
and willow shoots and other plants
replanted from the inside bend. By
doing this, we are ensuring that the
river will be populated by local,
natural plants. It will also stabilise
the banks and trap natural sediment
during floods. The designs FIGURE 4 Future state of the River Mersey works
consciously avoid hard engineering
techniques, such as concrete
revetments or permanent steel pins
for stability, and also encourages the
habitats that have been disrupted to
repopulate. We also want to leave
the site looking as natural as
possible, with no sign of us having
been there.
As seen in Figure 5, the top and tail
of the TLHB are being tied into the
existing banks to ensure that the river
does not simply get behind the
reinstatement and continue to erode.
The new, straighter channel means
that the water can flow much faster
and with more energy, therefore the
decision was made to add an
attenuation riffle in the middle of
the river course (Figure 6). This acts
as a speed bump for the water,
forcing the water up and over the
riffle and plunging it into a pool. A MY INVOLVEMENT to do this, I needed to raise the funds
proof of concept study was The River Mersey remediation project within Cadent. This involved financial
undertaken to prove that the is one that I have managed from the sanctioning documents and risk
migrating salmon in the river can very beginning. It was handed to me balancing with budgets.
still swim upstream. to run back in February 2017, when From that point on, I have been the
Unfortunately, over the winter of the inspector first noticed there was Project Manager and sole point of
2017/18 the river undermined and an issue. This is the first project of this contact for all stakeholders. This
destroyed a sand martin colony on type and size that I have managed, involves regular consolidation and
the TLHB. Sand martins are small, and it has been a steep learning curve agreements with the Environmental
ash-grey swallows that colonise for me. However, it has also been a Agency, hotel owners, councils, farm
sandy river banks near bodies of fantastic opportunity to manage a tenant, contractors, National Grid and
water. As part of the negotiations for multidisciplinary gas, civil and even local and corporate public
the Environmental Permitting environmental engineering scheme. relations teams.
Regulations (EPR) and access to the My first action was to involve the I have had to make decisions on
TLHB, we have decided to create a contractors, Northern Divers, to come behalf of Cadent (with guidance)
new nest for the sand martins. out and do an initial survey. In order concerning designs, costs and

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