| Background: | ||||
|
The Myrke Ditch is a 400-metre section of the Jubilee River Flood Alleviation Channel close to Eton. The entire section had eroded at the outer bend below a bridge structure. Salix were invited to tender for the specialist installation of the reinforced wildflower turf installation and the contract growing of the pre-planted coir pallets. |
|
|||
| Design: |
Myrke Ditch during works (16/11/2004) above and below |
|||
|
The
wildflower turf was reinforced with a three dimensional erosion control
geotextile to enable the turf to be installed in large rolls (2m by
20m). Access to the top of the bund was limited to a small mini digger,
which could only install off cuts of the wildflower turf but not the
full rolls. Additionally, a contaminated stream lay between the access
road and the bund. |
|
|||
|
Salix utilised a 25 tonne long reach excavator, with an extended reach
of 22 metres) to reach over the stream and allow the turf to be pulled
out by hand install the 1 tonne rolls of wildflower turf directly onto
the bund. The entire 5000 m2 of reinforced wildflower turf was
installed in just 4 days. |
||||
|
Laying reinforced wildflower turf at Myrke Ditch, Maidenhead. |
The reinforced wildflower turf was laid directly onto a woven geotextile. Previous trials demonstrated that a wildflower mix was capable of growing through this geotextile. The
grass and wildflower mix would not have been able to withstand the
regular inundations around the marginal fringe of the river. Salix were
asked to contract grow a specific mix of native wetland plants into 1m
by 2m coir pallets.
|
|||
|
Coir Pallets:
Phalaris arundinacea; Reed Canary Grass Juncus effusus; Soft Rush Lythrum salicaria: Purple Loosestrife Phragmites australis: Common Reed Iris pseudacorus: Yellow Flag Iris Carex acutiformis: Lesser Pond Sedge |
 |
|||
|
Pre-established coir pallets.
|
||||
|
In
order to withstand immediate winter flooding and intense grazing
pressure by waterfowl, “well-established” coir pallets were used. These
are extremely well rooted and are grown into the coir for 3-4 months
prior to installation. The use of well established coir stock also
meant that they could be installed out of season in October 2004.
|
||||
| Results: | ||||
|
The
project was an instant success with the bank appearing green from day
one. By June 2005 the wildflower and wetland plants had firmly rooted
and had begun to flower. The project had met all the engineering and
ecological objectives with the entire installation completed in just
one week.
|
||||
 |
 |
|||
| Myrke Ditch during works (left) and after works with well established wildflower turf (right). | ||||
|