METHOD STATEMENT AND RISK North Jeddah Pump Station
ASSESSMENT FOR ELECTRICAL CABLE TRENCH EXCAVATION
METHOD STATEMENT AND RISK ASSESSMENT FOR ELECTRICAL CABLE TRENCH EXCAVATION
CONTENTS
1 SCOPE OF WORK: 2 RESPONSIBILITIES: 3 SAFETY CONSIDERATIONS: 1Hazards 2Risk Assessment and Safety Precautions 3Personal Protective Equipment 4 METHODOLOGY: 1Prior to commencing work 2De-Watering 3For slewing and lowering BT duct 4Breaking the surface and excavating 5Size and depth of excavation 6Clearance to other services 7Preparing the trench 8Housekeeping
1. SCOPE OF WORK: Method for conducting excavation works for the electrical cable assessment and safety precautions.
trench together with its risk
2. RESPONSIBILITIES: 2.1 The site engineer and safety officer shall ensure staff involved in the excavation works adhere to this method and are qualified on the disciplines they are going to conduct. 2.2 The site supervisor and safety officer shall periodically monitor the compliance to this method statement. 2.3 The management representative will ensure that the process is monitored periodically. 2.4 If this method cannot be adhered to, the engineer in-charge must be contacted for advice before proceeding.
3. SAFETY CONSIDERATIONS: 3.1 HAZARDS Mobile Plant & Vehicles Noise & Vibration
Lifting Operations
Manual Handling Working near Lighting Levels Falls on Level Water Falls from Height Infected Materials Adverse Weather
Traffic
Fumes/Gas
Falls of material
Buried Services Overhead Services Fire/Explosions Flying Particles/Objects Heat
Dust Demolition Deep Collapse of Excavations Structure Confined Spaces Soft Ground
3.2 RISK ASSESSMENT AND SAFETY PRECAUTIONS
Risk assessment - Ensure that prior to starting work a site specific risk assessment is conducted and recorded to identify specific risks that may be present.
Risk Assessment Record : Trench Excavations Hazard Identified Impact with plant and underground services.
Persons at Risk
Controls in Place (Safety Precautions)
Workers
At all stages of the excavation, a safety officer must supervise the work and the workers given clear instructions on working safely in the excavation. If plant is being used above the trench then no operatives should be in the trench when the machine is in use. Area must be scanned for underground services & permit to excavate issued before work commences. Hand digging only in the vicinity of underground services. Electric cables adjacent to excavation should be isolated by electrician foreman issuing permit to isolate. Area of digging shall be secured.
R
Crushing
Workers
Security of excavation
Public
Lone Working
Workers
Contractor Competence
Cutting/severing
RISK RATING
Workers & Public
Workers
EQUIVALENT
1-4 5-9 10 – 16
C C B
17 - 25
A
Shoring should be in place if depth of trench warrants it along with extended poling boards & ladders for safe access/egress. Workers should ensure that shoring etc has been done to his satisfaction before descending into trench & gain access only by suitable access equipment. Excavations must not be adjacent to buildings and heavy plant kept away from edges. Stop blocks should be placed behind wheels of vehicles tipping into excavation. Do not store materials, waste materials or plant adjacent to excavation. Area must have HERAS fencing erected at a safe distance away from the excavation, ring fencing works. Fence panels should be double bolted at all joints, restricting access to authorized staff and contractors staff only. Plant and access equipment must also be secured when not in use. Excavation work is a minimum two man operation. Out of hours working is still a two man operation by competent workers. Supervising Officer will check the competence of contractor or subcontractor before engaging them. Contractor’s employees will have to complete street works course successfully as a minimum. Supervising Officer should request copies of excavation inspection report. If the workers are using a motorized saw they should ensure that they are wearing the correct PPE. Workers should be wearing ear defenders, goggles, gloves & hard hat. Ensure first aid kit and competent first aiders are available. Ensure workers wash hands before eating.
EQUIVALENT
No further immediate action Review periodically. Re-assess during next review. Within 3 months. (Improvement Notice). Reduce risk to acceptable levels and re-assess fo to ensure additional risks have not been introduced. Immediate (Prohibition Notice) Do not proceed until action has been taken to reduce the ri
Road works guarding
Plant, vehicles & work tools
Signs and barriers to be secured with sand bags if necessary. Maintain a safe route for pedestrians to by pass by the works. Guard pedestrians from vehicles when directed into carriageway. Where required lights to be attached to signing and guarding. To be kept inside the work area. To be in good working order and properly maintained. To have mufflers and silencers fitted where practicable. Vehicles to be fitted with, and use amber rotating beacon/s. Plant operators to be trained and competent in the use of the plant they are using. Switch plant off when not in use. Ensure that all guards are properly secured and unauthorised persons do not use the plant/vehicle. Rotate operators to reduce individual exposure. Keep plant & vehicles away from the edge of the excavation. Air hoses to be maintained in good order with joints correctly coupled. Hose check arrestors to be fitted and used on all compressed air lines. Dust suppression is to be used when saw cutting or using equipment that can cause airborne dust, i.e. water. Fuel oil to be stored and handled safely to prevent spillage or contact with skin or clothing. Ensure the correct PPE is used for the type of equipment. Ensure fumes do not enter confined space.
Safe digging Utility safe dig prints to be available on site at all times. Visual surveys to take place. All identified services to be marked on the surface. Pilot Holes will be excavated by hand to confirm positions of services. Ensure where necessary that correct trench wall supports are available and are used. Excavated material shall be stored a safe distance away from the excavation to stop possible collapse into the excavation, but kept within the guarded area. Mechanical excavation equipment shall not be used in the vicinity of other utility services. Adequate access/ingress to be maintained at all times.
Confined space working Ensure that gas-testing equipment is available, and is used when entering joint boxes or manholes. Where man entry is required ensure that all involved are trained and competent in confined space working and that there is an approved safe system of work and the confined space is continually gas monitored. Ensure that in confined spaces where there is no free flow of clean air, ensure there is adequate ventilation and where practicable used forced ventilation.
Safe lifting techniques
When lifting materials and tools from/to the excavation or onto/off the truck ensure that items are not too heavy. Either reduce them into lighter pieces or/and seek assistance to spread the load or use suitable lift equipment. If in doubt seek advice. When lifting manhole or box covers ensure that the proper lifting keys are used and that safe lifting techniques are employed. For carriageway covers lifting aids shall be used for lifting the covers wherever practicable, i.e. a suitable manhole lifter.
3.3 PERSONAL PROTECTIVE EQUIPMENT
Ensure the following is worn at all times during the works: Hard Hat Safety boots or wellingtons High visibility jacket or jerkin Coveralls
Ensure the following is worn as required during the works: Eye protection – grinding, sawing and cutting Ear protection – grinding, sawing, cutting, using jackhammers. Dust masks – grinding, sawing, cutting or conducting activities that involve airborne dust. Gloves – when using power equipment or manual handling.
4. METHODOLOGY: 4.1 PRIOR TO COMMENCING WORK
Survey the works to be done, picking the best position/route to excavate, taking note the required size of your excavation, the vicinity of previous excavations and the position of the other utility services. Read the service prints and conduct a survey as far as practicable mark all services in the vicinity of the excavation. Mark the surface to be excavated. Erect road works guarding and signs. Conduct trail holes to locate existing services and to see what effect they might have on the works. Gas test on any Jointing Chambers directly prior to entering and periodically during the works.
4.2 DE-WATERING
If de-watering is required during any stage of the work, then pumps and hoses should be positioned as to avoid any inconvenience to pedestrians, road traffic or other 3 rd parties. Before de-watering, ensure that Supervising Officer has agreed all discharge points. Samples of water should be taken prior to setting up the de-watering equipment. If the water shows any sign of contamination then the water should not be discharged and the Supervising Officer must be contacted. Ensure silt is not drawn from the excavation and where necessary use a settlement tank.
4.3 FOR SLEWING AND LOWERING BT DUCT
The Site Engineer shall calculate the amount of ground that requires excavating to obtain the movement, and clearly mark the area to be excavated. The Site Engineer shall check the Jointing Chambers ensuring that there is enough slack in the cables to provide the movement required. After conducting the calculations and marking the area, the Site Engineer must check that the planner has allowed for sufficient measure for the movement of the ducts.
4.4 BREAKING THE SURFACE & EXCAVATING
Identify the area marked for excavation by the Site Engineer. Where practicable, for large excavations in blacktop the surface shall be cut with a suitable road saw, however for small excavations a steel saw can be used. All excavation equipment used should be suitable for the work undertaken. Mechanical excavating equipment should not be used neat other services. Any service damages caused by previous contractor should be reported to the site engineer immediately. Excavated materials must be strictly controlled during all stages of the works, ensuring that it is stored at a practical and safe distance from the excavation, within the road works guarding. Material being collected by a grab wagon should be done in such a way to ensure that minimum disruption is caused to pedestrians, road traffic or any other 3 rd parties. Materials for re-use e.g. topsoil and granular materials, etc. should be kept free from contamination and where necessary protected from weather conditions. Control measures to prevent excavation collapse will be identified by a site specific risk assessment. Ensure that all apparatus is protected from damage prior to and during the works. All excavated services shall be adequately supported to prevent damage occurring to them.
4.5 SIZE AND DEPTH OF EXCAVATION New track work: Track width - The width of the excavation should be the width of the duct formation, plus 150mm (75mm + duct formation + 75mm). Gardens & Cultivated Ground – 450mm ( 45mm) depth of cover over the installed duct. Domestic Driveway, Footway & Soft Surface - the depth of excavation should be: Single way & 2 ways - 350mm ( 35mm) of cover over the installed duct. 3-way up to & inc. 20 ways - 450mm ( 45mm) of cover over the installed duct. Multi-way - over 20 ways and building lead in - 600mm ( 60mm) of cover over the installed duct Carriageway - the depth of excavation should be: Up to & inc. 20 ways - 600mm ( 60mm) of cover over the installed duct. Multi-way - over 20 ways and building lead in - 900mm ( 90mm) of cover over the installed duct Footway/Carriageway Interface – where the footway moves into the road 600mm of cover shall be provided as it enters the carriageway. 4.6 CLEARANCE TO OTHER SERVICES
Electricity High Voltage (>1000 volts), single cored cable – standard minimum clearance of 450mm. High Voltage (>1000 volts), multi-cored cable – standard minimum clearance of 300mm. Where this is impractical a clearance of >150mm will be allowed. If this cannot be achieved a concrete block or/and concrete of no less than 50mm thickness shall be placed between the BT duct and the electricity cable. The concrete block shall have an overlap on each side of the whole length of the reduced clearance, such that at every point the shortest path between the two services is no less than 75mm.
Other Services
Where possible 150mm clearance shall be given from other services such as gas, water, sewers, etc. Where plant crosses the minimum vertical clearance shall be 150mm for gas and 50mm for other services. Where the minimum clearance cannot be achieved, a BT approved separator shall be used, but under no circumstances can the clearance be < 25mm. 4.7 PREPARING THE TRENCH
The trench bottom shall be free from rock and stones. If this is not possible the trench shall be excavated slightly deeper and a layer of sharp sand or earth free from stones shall be laid and tamped on the trench base.
4.8 HOUSEKEEPING
The roadwork’s guarding and signs should be regularly checked. All spoil, materials, vehicles and plant should be properly guarded. The site should be kept as clean and tidy practicable during the works. Always be polite to the general public within the vicinity of the works and where necessary liaise with the local residents and other contractors present.
