PROJ/2017/0004 - Remedial and Upgrade Works to Spencer Jetty at Haulbowline Naval Base
Repairs to concrete structure, strengthening works to steel piles, protective coatings to concrete structure and steel piles, fendering system and wharf fixtures ( Further details contained in the Works Requirements).
Works Requirements for Remedial and Upgrade Works to Spencer Jetty
MALONE O’REGAN Consulting Engineers 17
SECTION 1 - GENERAL
1.1 General
Spencer Jetty at Haulbowline Naval Base comprises a 132m length of berthing
and mooring facilities to the north west of the entrance to the Dockyard Basin.
The jetty has fallen into disrepair and is currently not in use.
The Jetty was constructed in two phases:
Original Jetty, comprising reinforced concrete beams and slabs spanning to
primary beams and supported on piles. It is probable that strengthening works
were undertaken to this section of the jetty at approximately the same time as the
jetty was extended.
Jetty Extension, comprising reinforced concrete slabs and flat slabs spanning to
beams and concrete filled steel piles.
The existing structures are in a poor condition. Concrete discolouration, cracking
and spalling has occurred on beam soffits, beam ends, and in places on slab
soffits.
Reinforcing bars have been exposed by spalling concrete and signs of corrosion
are visible.
The supporting steel piles are also corroded and in places quite severely
corroded in particular in the low water and splash zones
An investigation carried out by BHP Laboratories in April/May 2018 demonstrated
that 3 out of 36 individual tests carried out on samples taken from 15 locations
record chloride content in excess of the maximum allowable percentage of 0.4%.
The investigation also found that the steel piles had suffered from corrosion and
that remaining pile wall thicknesses measured varied considerably. Average wall
thicknesses recorded at low water showed an estimated 52% reduction in pile
wall thickness.
1.2 Description of the Works
The Department of Defence intends to carry out remedial works to prevent further
deterioration of Spencer Jetty and also basic upgrading works to allow the Jetty to
be used as a lay-off and short-term berth for navy vessels.
The scope of works will include:
- Repairs to the reinforced concrete structures
- Repairs to the steel piles
- Application of protective coatings
- Installation of piling for the new fender system
- Provision of bollards, ladders, rails and temporary services
- Provision of cathodic protection
...etc
Repairs to concrete structure, strengthening works to steel piles, protective coatings to concrete structure and steel piles, fendering system and wharf fixtures ( Further details contained in the Works Requirements).
Works Requirements for Remedial and Upgrade Works to Spencer Jetty
MALONE O’REGAN Consulting Engineers 17
SECTION 1 - GENERAL
1.1 General
Spencer Jetty at Haulbowline Naval Base comprises a 132m length of berthing
and mooring facilities to the north west of the entrance to the Dockyard Basin.
The jetty has fallen into disrepair and is currently not in use.
The Jetty was constructed in two phases:
Original Jetty, comprising reinforced concrete beams and slabs spanning to
primary beams and supported on piles. It is probable that strengthening works
were undertaken to this section of the jetty at approximately the same time as the
jetty was extended.
Jetty Extension, comprising reinforced concrete slabs and flat slabs spanning to
beams and concrete filled steel piles.
The existing structures are in a poor condition. Concrete discolouration, cracking
and spalling has occurred on beam soffits, beam ends, and in places on slab
soffits.
Reinforcing bars have been exposed by spalling concrete and signs of corrosion
are visible.
The supporting steel piles are also corroded and in places quite severely
corroded in particular in the low water and splash zones
An investigation carried out by BHP Laboratories in April/May 2018 demonstrated
that 3 out of 36 individual tests carried out on samples taken from 15 locations
record chloride content in excess of the maximum allowable percentage of 0.4%.
The investigation also found that the steel piles had suffered from corrosion and
that remaining pile wall thicknesses measured varied considerably. Average wall
thicknesses recorded at low water showed an estimated 52% reduction in pile
wall thickness.
1.2 Description of the Works
The Department of Defence intends to carry out remedial works to prevent further
deterioration of Spencer Jetty and also basic upgrading works to allow the Jetty to
be used as a lay-off and short-term berth for navy vessels.
The scope of works will include:
- Repairs to the reinforced concrete structures
- Repairs to the steel piles
- Application of protective coatings
- Installation of piling for the new fender system
- Provision of bollards, ladders, rails and temporary services
- Provision of cathodic protection
...etc
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