23
d
&
ri
MARCH-APRIL 2014
EXPLOSIVE
DEMOLITION
DEMOLISHING THE CHIMNEYS OF
THE RICHEMONT POWER PLANT
INCLUDED:
■
30 000 work hours
■
Asbestos removal
■
Mechanical demolition
■
10,000 tonnes of concrete
■
1,200 tons of scrap metal
■
1,000-bar ultra-high pressure cleaning
and depollution
■
Debris netting - Strength: 1.5 tonnes
■
Refilling before demolishing
■
Concrete sawing
■
Core drilling
■
Weakening of the structure
■
Test firing
■
Vibration analysis
■
Guidance and load recovery system
■
Source protection measures
■
Vibration management:
■
Terrain loosening
■
Anti-vibration trenches
■
Dust management
■
Site clean-up
The end
of power
French contractor Cardem was shortlisted for the work it
carried out during the removal of three redundant chimneys
at the Richemont Thermal Power Plant
The chimney of
generating unit 4 was
made of brick between
the heights of 12 and 72 m (40 and 236 ft).
Finally, the chimney of unit 5 had a metal tube
interior between the heights of 12 and 115 m
(40 and 377 ft).
Given the safety and technical context,
C
ardem was selected to demolish the
three chimneys of the Richemont
Thermal Power Plant, a project that
represented six months of work, carried out
with EDF as the contracting authority and
Cardem as the prime contractor. Cardem’s
role consisted of the demolition of three
chimneys, standing 75, 111 and 115 m (246,
365 and 377 ft) high respectively with the
smallest chimney having
a brick-lined interior and
a concrete exterior.
The chimneys
belonging to generating
units 4 and 5 comprised
two tapered cylinders in
reinforced concrete, the
first one dating back to
the start-up of the plant,
with a variable thickness
from 19 to 8 cm (7.6 to
3.2 inches) from bottom
to top, and the second one with a constant
thickness of 15 cm (6 inches). The latter
was added for reinforcement after several
years of operation, thereby creating a double
thickness.
The Richemont Thermal Power
plant with the three chimneys
still standing
Diagnosis of concrete strength and properties
was determinated by core boring and sclerometer
measurements
Because of varying concrete qualities, holes for the
explosive charges were drilled in staggered rows
