Arsenal Sewer Diversions.
Clients: Thames Water and Enterprise (for Sir Robert McAlpine)
Duration: 26 weeks
Location: New Arsenal Stadium, Ashburton Grove, London N7
Description of works:
The new Arsenal Stadium is being constructed over the existing Holloway
Storm Relief Sewer and a local brick egg combined sewer. The area is a
brown field site, previously utilised as a waste transfer station.
M&A Roarty Construction, on behalf Enterprise carried out the relocation
of the existing local sewer by construction of 100m of 1800mm diameter
sewer and 180m of 1200mm diameter sewer. All manholes were constructed
in situ RC to suit the requirements of the developer.
Additionally an existing overflow arrangement from the local sewers to the low
level storm sewer was repositioned within the site. This work consisted of the
construction of a 5.0m internal diameter caisson shaft. The shaft was sunk
within 8m of an adjacent railway embankment. All Contractor Method Statements
and Risk Assessments were subject to approval by London Underground Limited.
The shaft, sunk to a total depth of 18m below existing ground level, includes
3 no. galvanised half landings and associated safety railing. The shaft broke
through the existing 2.1m diameter storm relief sewer, the crown of which lies
approximately 14m below ground level.
The caisson had 2 no. supported openings broken through prior to passing
down through the existing sewer, these eyes ensured that the flow through
the storm sewer was maintained at all times. The sinking of the caisson
through the sewer was carried out using continuous 24 hour working over a
4 day period.
A 600mm ID GRP backdrop was constructed within the shaft. The backdrop
will collect flows from an insitu RC weir box constructed immediately adjacent
to the shaft, dimensions approx 8.0m x 6 x 4.5m deep.
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