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Scope
Reference documents Definitions
Responsibilities Safety
Method Equipment Attachment
Scope
This statement is aimed to propose the procedures to be adopted to precast the manholes, catch basins and fire water main valve box (wherever so required to be used precast) chambers and install in specified prepared locations.
Reference Documents
Drg Man Holes Drg Man Holes Drg Man Holes Drg Man Holes Drg Catch Basins Drg Catch Basins Drg Catch Basins Drg Typical Details Specifications Definitions
PSM Project Site Manager CM Construction Manager.
CS Construction Superintendent FM Foreman
QC Quality Control
Responsibilities
PSM shall control the overall operations
CM shall arrange the resources required accordingly
CS shall control, monitor and direct the FM and workforce for the operations FM shall execute the operations deploying the workforce
QC shall inspect all the operations according to the specifications EPC Contractor shall conduct surveillance
Statements were written by Professional Eng Suraj Singh Project Manager as well as Senior Project Engineer. Most of these were approved by EPC Contractor & Company (no sketches
Safety
Every day prior to the commencement of any activity, the work personnel shall receive a Tool Box talk relevant to the operation according to the project safety requirements.
A safety inspector shall inspect the operation daily and direct the Foreman and superintendent address the snags if any
Method
The following activities shall be involved:
To prepare a precasting yard on site
To fabricate the form works according to design details To fabricate the box outs to be used in forms
To fabricate the reinforcement
To place the rebars and the non critical cathodic protection
To cast bases with a kicker and shear key as shown in the first stage and cure To scabble the kicker to roughen the construction joint surface
To cast walls with pipes inlet and outlet boxes formed in the second stage with the lifting hooks To cure the cast units
To cast the cover slabs in the third stage and cure Excavation of the relevant area / s
Blinding and membrane
Transportation of the completed open units to the locations Installation of the units on the correct alignment and levels
Inspections by Civil Contractor QC and EPC Contractor approval To prepare the cover slab bearing mortar bed as specified
To provide the box out sleeves for steps insertion Pipe laying by others
To install the seals around the pipes and the box out concrete To cast the surrounding concrete 150 mm thick as specified
To apply 1 mm thick coal tar epoxy on the external surfaces as specified To bench the invert levels between the pipe flows where specified
Inspections by Civil Contractor QC and EPC Contractor approval To plug the pipe spigot ends
To place the covers Details
A precast yard having a capacity of about 20 units as shown on the attached sketch shall be used for the precasting operations
The yard shall have convenience for the vehicles to freely move for various activities Strong platforms of 100 mm thick concrete shall be used as the casting bases / floors In one go about 10 units shall be made ready for the bottom slab pouring
The overlap shall be provided from the top of the kicker as specified and if so convenient the rebars shall be fabricated continuously
The formwork for the base slabs with kickers to be cast monolithically shall be prepared according to the typical sketch attached
Required rebars shall be placed in the correct locations with 75 mm covers / spacers
Shear key forms shall be erected according to the details and well clamped in
Civil Contractor QC inspection shall be conducted followed by EPC Contractor approval The concrete shall be poured through a chute
The curing shall be carried out by spraying compound and later by saturated hessian and polythene cover
The wall formwork shall be fabricated on site using marine ply The internal forms shall be fixed first to the correct dimensions
The box outs shall be fixed to the required locations on the fixed forms
The rebars for the walls as well as the trimming around box outs shall be placed in position The external forms shall be fixed around well supported, in plumb and correct dimensions The lifting lugs shall be placed in the required locations in the walls using 16 mm dia rebar according to the detailed sketch attached
A binding wire length shall be tied to the horizontal rebars in continuity connected to the boss fixed near wall top for the cathodic non critical arrangement / connection
Civil Contractor QC inspection followed by EPC Contractor approval
Pouring concrete into wall forms with wood float top surface finish and curing by compound and later by hessian and polythene cover for the specified period
Forming cover slab shutters according to the specified details Forming the cover box out shutters into the required position Placing the rebars into the correct positions
Fixing the cover lifting hooks according to details attached
Civil Contractor QC inspection followed by EPC Contractor approval Pouring concrete and curing as aforesaid
Inserting the steps shall be carried out by fixing the pieces into the preformed holes in the concrete walls as created by box sleeves with approved grout at a stage when the concrete has gained sufficient strength
The excavation shall be carried out to the specified level and alignment followed by blinding and water proofing
The open precast chambers shall be crane lifted and transported by a trailor to the relevant locations followed by offloading into the correct alignment
The pipes shall be laid by others
After the pipes are laid, specified seals shall be placed in with the surrounding concrete as well as the box out void forms erected followed by concrete pouring into the box out voids and the plug(concrete surround)
The benching wherever specified shall be formed according to the channel flows and the details
The bedding of the joint 20 mm thick shall be carried out on site as specified
After the levels and the alignment are ensured, the cover slab shall be correctly placed in followed by the formation of the concrete block work pad to suit the cover elevation
The cover shall be set in on the block work pad using cement sand mortar The mass concrete shall be laid around the cover as specified
The external surfaces shall be applied with 1 mm dry film thickness non solvented coal tar epoxy in accordance with project specifications
Civil Contractor QC inspection followed by EPC Contractor approval
Statements were written by Professional Eng Suraj Singh Project Manager as well as Senior Project Engineer. Most of these were approved by EPC Contractor & Company (no sketches
The whole levels and the alignment details shall be documented according to requirement
Equipment
Crane
Concrete Transit mixer Trailer
Vibrator
Attachment
Yard layout Kicker details
Sketch showing lifting hooks for unit walls and base Sketch showing lifting hooks for cover slab
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