The Greenway Flood Alleviation Scheme


Clients: Total Pipeline Solutions and Thames Water 

Duration: 26 weeks 

Location: Edgware, London HA8



             



Description of works: 


M&A Roarty Construction, on behalf of Total Pipeline Solutions
constructed a 15m Ø x 20m deep steel reinforced concrete shaft. 

The project also included: 
2 No 2.59m I.d. segmental shafts
1 No 3.66 I.d. segmental shaft
60m 450mm dia. Off-line p.c.c. pipework, 3 - 4.5m deep

The use of the Shotcrete construction technique on the main shaft,
whereby a 750mm excavation was achieved by miners in the first half
of the shift, followed by fixing of steel reinforcement and build up of 
the spray concrete shaft wall during second half of shift.
The sprayed concrete had accelerators added to enable a build up of
a typically 400mm thick shaft wall.
The cover slab was precast in sections and was placed in one day, 
using a 300 tonne mobile crane.
The use of sprayed concrete to construct a shaft was a first for a
Thames Water project.
The shaft, with a capacity of over 3M litres, will hold the surcharge 
from an adjacent 800mm foul sewer during storm conditions.
The design and construction of the shaft base in 450mm thick sprayed
concrete produced an enormous saving in the volume of concrete required 
compared to the conventional plugs for segmental shafts.

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