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7/29/2019 Swamp Embankment Widening - Method Statement
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SUMMARY OF CONTENTS
1. Scope of Method Statement.3
2. Scope of Works3
3. Reference Documents ..3
4. Materials .3
5. Plant and Labour ..3
6. Sequence of Works4
7. Hazards and Risks..7
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1. Scope of Method Statement
This Method Statement describes the works operation to undertake mass
earthworks and Sub Grade Construction that comply with the specified
requirements for widening of existing road under swamp conditions.
2. Scope of Works
The works covers all work in connection with the construction of fillsincluding, clearing and grubbing, the removal to spoil of material unsuitable
for use, the construction of a construction platform, and the construction
and compaction of fills with cut material from the road prism or borrow
material from approved sources and the finishing off of cuts and fills, up to
the stage where fills are ready for the placing of the pavement layers.
3. Reference Documents
General Specification for Road and Bridge Works, Republic of UgandaVolume 3A Sections 3200.
Special Conditions of Contract Tender Dossier Volume 4 Section 3200 Quality Control Plan: Swamp Embankment Widening.
4. Materials
Borrow materials complying with specification, and approved by the Engineer,
Rock fill material (max size 200 mm). Graded Crushed Stone. Biaxial geogrid
reinforcement, and Polypropylene Filter Fabric.
5. Plant and Labour
1 x 140 H Grader 1 x Self propelled single drum vibrating roller 1 x Cat 320 Excavator 1 x D4 Dozer 1 x 18000 Litre Water Carts 2 x 4 Water Pump Labour and Flagmen
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6.Sequence of Works Drain water away from the fill areas by pumping, installing
drains, deviating streams or constructing cofferdams and
pumping out.
Establish toe pegs for the widening within the swamp area. Cut down vegetation within the toe peg are level with thesurface. (Do not remove roots) Accommodate traffic maximum 1km half width under traffic
lights or stop/go conditions.
Ensure survey poles/batter boards and levels have been placed. Cut the first bench as shown on the drawings, and place a layer
of polypropylene filter fabric on top, folding at least 1 metre
width up against the bench, and securing if firmly in place.
Place a layer of biaxial geo grid reinforcement on top of thefilter fabric up to the vertical face of bench and secure inplace.
Next, by end tipping over the side and placing with a small D4Dozer a 100mm layer of crushed stone base is placed and
compacted; this is followed by a 200mm layer of rock fill placed
in the same manner.
Following this, a second layer of biaxial geo grid reinforcementis secured on top of the rock fill and tied into the existing
benched embankment. The construction platform is then
completed by placing and compacting rock fill until a total layer
thickness of 600mm is achieved. Blinding layer will be placed on
top of the rockfill as per specification. The whole platform is
then encased in polypropylene filter fabric by pulling the folded
1 metre width left at the bench across and down the outside of
the platform layer.
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Further layers of approved fill material shall then be placed andcompacted in 200mm layers, each layer being subject to the
Engineers approval before the placement of subsequent layers.
A maximum of 1 metre fill will be allowed per week. When the fill has been completed and approved to selected subgrade level, the sub base material shall be tipped, spread and
lightly compacted, before being opened to traffic for a period
of up to six months to allow for settlement of the fill, prior to
stabilizing the layer.
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Survey /Setting out of Works
Obtain approval for borrow/excavated material for the use in fill
Clearing and Grubbing by Hand
Cut first bench
Place layer of filter fabric
Place layer bi axial geogrid
Place 100mm, layer of Graded crushed stone and proof roll
Place 200 mm layer of 200mm rockfill
Place 2nd
layer of bi axial geogrid
Place 300mm layer of -200mm rockfill
Place blinding layer on top of rockfill as per specification
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Encase whole platform in Polypropylene Filter Fabric
Complete fill in 200 mm layers < I metre per week
Construct Selected Subgrade
Tip and Spread Sub Base Material
Open to traffic for 6 months to allow for settlement
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7. Hazards and Risks
Risk assessmentsRefer to: - Health and Safety Plan 110.199/PRM/QSE/HSP/001
- BASIL READ Hazard Identification and Risk Assessment
Forms
On going risk assessments and training of personnel is seen as paramountimportance to site management with the view to maintain a high priority on
safety risks issues.
Environmental risksRefer to: - Environmental Management Plan: 110.199/PRM/QSE/EMP/001
The following environmental risks have been identified:
Preservation of topsoil Limiting the clearing of trees and indigenous flora Contamination of wetlands/swamps Contamination of watercourse with pollutions Contamination of streams, gullies and irrigation cannels with slit Dust Fuel and oil spillage Smoke and vapor emissions Portable toilets and site amenities
Measures to control and minimize risks are in place and the monitoring of
these controls remains the responsibility of all site personnel.