Category

Construction Safe Work Method

Category

Concreting Operations

Operations followed in the making of concrete in compliance with the safety and quality requirements are known as concreting operations. Concreting operations include:

  • Storage of materials;
  • Batching and Mixing of various ingredients;
  • Concrete mix transportation;
  • Concrete placing;
  • Compaction of concrete;
  • Surface finishing; and
  • Curing of concrete.

PURPOSE

Concreting operations are vulnerable to safety and health hazards. This method statement describes the safety requirements and safe work procedure for concreting operations to:

  1. Prevent improper carrying out of concreting works;
  2. Carry works in a manner that’s safe at all times;
  3. Know the hazards involved in performing the activity;
  4. Ensure controls are in place to steer clear of hazard exposure.

Use any other resources and methods not referred to in this method statement to suit the project requirement. Execute the work safely complying with the required standard.

The sequence of activities is a repetitive process and many hazards are common to distinct sites. Include with detail, any crucial information specific to the project. Follow the approved checklists prior to the start of the activity.

PROCEDUREs in concreting operations

Storage of concrete materials

Storage of cement:

  • Store cement in a weatherproof shed to keep it dry,
  • Make proper arrangements to prevent rain penetration,
  • Store cement on a platform raised above ground level.

Storage of Aggregates

  • Keep aggregates in a clean condition. Take necessary measures to prevent contamination with undesirable substances,
  • Make floor of the storage bins with plain cement concrete,
  • Separate storage bins with partitions to prevent mixing of different aggregate sizes.

Batching and Mixing of materials

  • Inspect and check the batching equipment including equipment calibration before the operation begins.
  • Weigh the cementitious materials and aggregates independently in separate compartments.
  • Ensure that the weigh hopper charging and discharging gates close tightly when producing concrete.
  • Make sure that the equipment allows to control the material flow rate and stop the flow within the specified weighing tolerance.
  • Make sure that the measuring accuracy of batch materials weighing scales, and the water measuring equipment meets accuracy requirements before the work begins.  

Concrete mix transportation

The operation of moving concrete mix from the concrete batching plant to the concrete pour location is known as concrete mix transportation.

Ensure that the water-cement ratio and slump are maintained as per concrete design mix before placing of concrete. During transportation, the concrete mix shall maintain its cohesiveness and workability.  

Placing of concrete

Concrete placing
Concrete placing (image credit By Rasbak)
  • Check the formwork and reinforcement before placing the concrete to ensure that they are clean and free of any debris.
  • Deposit the concrete as close as possible to its final position. Make sure that reinforcement dislodging or overfilling of formwork doesn’t occur during concrete discharge.  
  • When filling columns and walls, take care that the concrete does not strike the formwork face, which might impact the surface finish.
  • For deep sections place the concrete in layers that are uniform, generally not exceeding 500 mm thick, each layer being fully compacted.

Compaction of concrete

After the concrete is placed, it contains entrapped air voids. Compaction is the process to expel entrapped air from concrete. Consequently, compaction increases the density of concrete.

Three types of vibrators are available to achieve the desired compaction:

  1. Immersion vibrators or needle vibrators: appropriate for all sorts of sections. As per IS: 3558 [Code of practice for use of immersion vibrators for consolidating concrete],  “the vibrating needle should preferably be inserted vertically. The insertion at an angle, in thick layers, may leave concrete unconsolidated without any indication at the surface.” 
  2. Surface vibrators:  They are appropriate for compacting slabs, industrial floors, road pavements, and similar flat surfaces. Furthermore, they also aid in surface leveling and finishing.
  3. Table vibrators: Vibrating tables are used for the consolidation of concrete in moulds for the manufacture of plain and reinforced concrete or prestressed concrete elements. IS 7246 [Recommendations for use of table vibrators for consolidating concrete.]
  4. Form vibrators: For complex members or members with higher reinforcement congestion, form vibrators are appropriate. They are fixed to the exterior of the formwork. Therefore,  these are also called external vibrators. The formwork needs to be designed to resist the forces imposed on it by form vibrators.

Concrete surface finishing

Concrete surface finish
Concrete surface finish

Finishing is the operation of attaining a concrete surface of desired texture and pattern. Functional and decorative requirements determine the finish of a concrete surface.

As per IS 2571 [Code of practice for laying of in-situ cement concrete flooring]:

The floor finishes shall be laid depending upon the expected load and wear on the floor and the fact whether the topping is to be laid monolithic with the base or separately on a set and hardened base. In either case, special precautions are necessary to ensure a good bond between the topping and the base.”

Finishing makes concrete more functional and aesthetic. Concrete that will be visible, such as driveways, highways, or patios, often needs finishing. Concrete’s end use usually determines the final surface texture and patterns.

Finishing of concrete surface requires one, or many of the following operations:

  1. Level the surface
  2. Edge the concrete
  3. Joint the concrete
  4. Float the concrete
  5. Trowel the concrete
  6. Texture the concrete surface
  7. Cure the concrete

Never add cement or sprinkle water on concrete while finishing it.

Curing of concrete

As per ACI 308R [Guide to Curing Concrete], curing is the process by which hydraulic-cement concrete matures and develops hardened properties over time as a result of the continued hydration of the cement in the presence of sufficient water and heat.

Curing is to maintain desired water content within the concrete for the required time. Start curing of concrete as quickly as possible after finishing of concrete.

HEALTH, Safety, AND ENVIRONMENT for concreting operations

Safety is essential and imperative part of the construction process. Provide personal protective equipment (PPE) to all personnel involved in the Diaphragm wall activity and provide the required safety equipment.

Below are the suggested PPE for concreting operations:

PPE for concreting operations
Safety PPE for concreting operations

Safety Measures for concreting operations:

  • Formwork shall support, without failure, the anticipated vertical and lateral loads. Make sure appropriate design, fabrication, erection, and supports for the formwork,
  • Before erection, inspect shoring equipment to determine that the equipment meets the specified requirements,
  • Inspect erected shoring equipment before, during, and immediately after concrete placement,
  • Make sure all base plates, shore heads, extension devices, and adjustment screws are firmly in contact, and adequately secured, with the foundation and the formwork,
  • Prohibit eccentric loads unless designed for such loading,
  • Provide adequate supports to reinforcing steel installed for vertical structures like columns, walls etc. The supports are needed to prevent overturning and collapse,
  • Vibrator crews should not work under concrete buckets suspended from cranes or cableways,
  • Wash off, as soon as possible,  any concrete splatters on the skin,
  • Provide scaffolds or work platforms for all vertical slip forms where employees need to work or pass,
  • Below are the most critical practices that are unsafe and need to be avoided:
  1. premature removal of formwork;
  2. failure to brace masonry walls;
  3. failure to adequately support precast panels;
  4. inappropriate operation of equipment;
  5. failure to guard the end of reinforcing steel; and
  6. inadequate shoring, which may lead to formwork collapse.
  • Don’t load the concrete with any construction loads till the structure is capable of taking such loads as per the structural design,
  • Guard all protruding reinforcing steel, onto which an individual could fall,
  • Don’t let any person work under concrete buckets while the buckets are in motion,
  • Don’t expose any person to the hazards associated with falling concrete buckets.

Safety questions

Keywords: Concreting operations; Safe Work Method; Construction work procedures.

Diaphragm wall

Diaphragm wall is a technique used to construct reinforced concrete walls in the ground after deep trench excavation. The walls act as cut off wall or serve as a structural member. Excavated trench creates a form for the wall. The trench is filled with bentonite slurry continuously circulated at all times. The slurry provides outward pressure to balance the inward hydraulic pressure. This prevents the trench from collapsing and prevents water flow into the trench. Mechanical excavation techniques like rotary or percussion or grabbing or a combination are utilized for trenching. The reinforcement cage is then lowered and the trench is filled with the concrete that displaces the slurry. Usually, the width of the wall varies from 450 to 1200 mm and depths anywhere between 20 to 50 meters. Inclined rock anchors are used to anchorage the diaphragm wall structure to withstand the lateral thrust on the wall. Continue reading to find out detailed Diaphragm wall construction procedure.

Diaphragm Wall Applications

  • Underground stations
  • Multi-level car parks
  • Open cut tunnels
  • Bays in the water for shipbuilding and ship repair
  • Quay Walls
  • Tunnel ventilation shafts
  • Support for open or top down excavations
  • Groundwater flow barrier
  • Retaining wall
  • Cut-off provision to support deep excavation
  • Final wall for basement or other underground structure (e.g. tunnel and shaft)
  • Separating structure between major underground facilities
  • As a form of foundation (barrette pile –rectangular pile)
  • Used in congested areas
  • Practically suited for deep basements.

Diaphragm Wall types

Diaphragm walls are of two types. T-Shape Panel and L-Shape Panel

Diaphragm wall types
Figure 1: Diaphragm wall types

Diaphragm Wall Advantages

  • Faster Execution. Considerable reduction in basement construction time.
  • Designable to take high horizontal and vertical loads and bending moments.
  • An economic and favorable solution for a large deep basement in saturated and unstable soil profiles.
  • Savings in construction costs as a single element can be used as a supporting wall, a cut-off wall, and a deep foundation element.
  • Construction is possible near existing buildings. A clearance of only 30 cm from the outer walls of buildings is adequate.
  • Low environmental impact throughout the works. Construction causes only moderate noise.
    No vibration during installation.
  • For inner-city areas, the top-down method will help to optimize the operation sequence.

Equipment

Equipment nameUsed for
D wall rig with Kelly grab with various dimensions.Trenching / excavation through soil / competent strata.
Service CraneReinforcement Lowering & Concreting
Excavator or JCB and dumperRemoval of soil, Spoils.
Stop ends.Forming joints between panels
Stop ends extractor/chisel.Removal of stop ends.
Polymer setup.Mixing Polymer / stabilizing fluid
Pumps.Suction pump; Submersible pump;
Slurry pump;
Water pump.
Tremie set and Accessories.Concreting works.
Welding Machines.Cage Fabrication.
Diesel Generator.Power Generation.
Sounding chain and tape.Depth checking
Office Container & Workshop.Site office and maintenance.
Diaphragm wall Equipment
Figure 2: Diaphragm wall Equipment

Diaphragm Wall Construction Procedure

 

Diaphragm wall construction procedure
Diaphragm wall construction procedure

Figure 3: Diaphragm wall construction stages

  • Stage 1: Construction of Guide Walls
  • Stage 2: Preparation of the Supporting Slurry
  • Stage 3: Excavation of Diaphragm-wall and Stop ends fixing
  • Stage 4: Lowering of Reinforcement Cage
  • Stage 5: Concreting  Operations & Stop Ends Removal

Guide wall construction

Diaphragm wall Guide wall
Diaphragm wall Guide wall

Figure 4: Diaphragm wall Guide wall construction

Guide walls are two parallel concrete walls along the face of the wall. Excavate and construct 250 mm thick and 2 meters deep RCC guide walls on each side of the diaphragm wall center line. The guide walls direct the clamshell or grabbing equipment to maintain the desired width, keeps vertical alignment and retains bentonite slurry. Typically, a vertical tolerance up to 1:200 is permissible for diaphragm wall construction.

Supporting slurry

Diaphragm wall supporting slurry
Diaphragm wall supporting slurry

Figure 5: Diaphragm wall supporting slurry arrangement

Make bentonite tank and circulation arrangements for desanding and centrifuge. Typical capacity required is 100 to 500 cum per hour. Circulate the bentonite fluid continuously with reverse mud circulation to prevent side collapse. Always keep bentonite slurry level at minimum 1 meter higher than the groundwater table. Clean the slurry fluid to achieve the desired limits of density, content, viscosity, and PH. Use flocculants if the demand to remove fine silty solids and clay solids from the slurry.

Typical parameters for slurry

Slurry parameters
Slurry parameters

Excavation

Diaphragm wall excavation
Figure 6: Diaphragm wall excavation

Excavation is done by digging technique using clamshell or grabs to the desired depth. For sand and soft rock strata, excavation by cutting technique using reverse circulation trench cutters can be used. Excavation is accomplished with the Hydrofraise or comparable drilling methods. A heavy metal frame, serving as a guide, is mounted at its base with two cutting drums carrying tungsten carbide tipped cutters. A pump is placed just over the drums and evacuates the loose soil, which is carried up to its surface by its drilling mud. The mud with cuttings is continuously filtered and then poured back into the trench.

Diaphragm wall Panels

Diaphragm wall panels
Figure 7: Diaphragm wall panels

Constructing long sections of wall continuously is not possible due to limitation and size of the plant. The wall is usually constructed in alternative section leaving an intermediate section in between. Two stop end tubes will be placed at the ends of the excavated trench before concreting. Withdraw the tubes at the same time of concreting in order that a semi-circular end section is shaped.
The in-between segments are built similarly subsequently, but without the end tube. By the end, a continual wall has been built with the panel sections closely joined by the semi-circular groove.

Stop Ends Fixing

Stop ends fixing with water stops

Diaphragm wall stop ends fixing
Figure 8: Diaphragm wall stop ends fixing
Diaphragm wall two water stop system
Figure 9: Diaphragm wall two water stop system
Diaphragm wall single water stop
Figure 10: Diaphragm wall single water stop
Diaphragm wall double water stops
Figure 11: Diaphragm wall double water stops

Reinforcement

Diaphragm wall reinforcement cage lowering
Figure 12: Diaphragm wall reinforcement cage lowering

Diaphragm wall reinforcement cage lowering
Figure13: Diaphragm wall reinforcement cage lowering

Diaphragm wall reinforcement cage installation

Figure 14: Diaphragm wall reinforcement cage installation

Lower the reinforcement cage in the excavated trench. Reinforcement cage must have a sufficient transverse and diagonal reinforcement. This is to withstand lifting and lowering handling forces. Good space must be available inside the reinforcement cage for tremie pipes to pour concrete.
Concreting: Concrete is placed with tremie pipes to prevent the segregation of concrete. The concrete progressively replaces the slurry. Lift the tremies progressively as the concrete level raises. Maintain a minimum depth of 0.6 meters of tremie pipe into the concrete.

Concreting and Stop ends removal

Diaphragm wall Concreting
Figure 15: Diaphragm wall Concreting

Diaphragm wall Stop ends removal
Figure 16: Diaphragm wall Stop ends removal

Concrete is placed with tremie pipes to prevent the segregation of concrete. The concrete progressively replaces the slurry. Lift the tremies progressively as the concrete level raises. Maintain a minimum depth of 0.6 meters of tremie pipe into the concrete.

Quality Assurance and Quality control

  • Submit a detailed inspection and test procedure
  • Maintain concrete pour cards and checklists during pre-pouring, pouring and after-pouring.
  • Cast the concrete cubes at the specified frequency.

Standards

IS 456 : 2000 – Code of Practice for Plain and Reinforced Concrete

IS 9556 : 1980 – Code for practice for design and construction of diaphragm wall

Health and Safety

Safety is essential and imperative part of the construction process. Provide personal protective equipment (PPE) to all personnel involved in the Diaphragm wall activity and provide the required safety equipment. Below are the suggested PPE:

Safety Helmet
Safety Helmet

Safety Footwear
Safety Footwear

Safety Glasses
Safety Glasses

Safety Ear Protection
Safety Ear Protection

Safety Vest
Safety Vest

Safety barrier
Safety barrier

Safety Procedure of Diaphragm wall Construction

  • Inspect the rig/service crane by the lifting supervisor and operator with the provision of the checklist.
  • Cordon off the working area with red-white safety tape when the boring rig/service crane is in operation.
  • Allow no person other than the crane operator, safety supervisor, and lifting supervisor to engage in the lifting works.
  • Keep unauthorized personnel out of the lifting works area.

Safety Procedure of night work

  • Provide sufficient lighting for the night shift at the working area.
  • All night shift employees shall wear reflective jackets.
  • All activities will be under close supervision.

Safety Supervisor activities during execution

  • Conduct toolbox meeting once or twice a week prior to the commencement of work.
  • Conduct safety inspection and safety meetings.
  • Arrange safety induction for new workers who enter first time into the site.
  • Issue PPE for all workers and maintain a record for the same.
  • Keep appropriate equipment and machinery certificates on site.
  • Record accidents in “Accident Report Form”.
  • Ensure good housekeeping on site

Risk Identifications

  • Risk of damage to “live utilities”.
  • Risk of public wandering into the work area.
  • Risk of site personnel falling into the excavated trench.
  • Risk of traffic accidents within the site.

Risk Management

  • Mark and display clearly the type of utilities.
  • Allow only authorized persons with permission.
  • Use appropriate PPE before entering into the work site.
  • Cordon off the area around the openings.

 

This article on Diaphragm wall construction procedure and all the images were contributed by Keller Ground Engineering India Pvt. Ltd.

About the Keller Group: Keller is a leading international ground engineering specialist with offices in over 30 countries on five continents. Whatever the size of the project, and wherever it is, Keller has the experience and technology to provide an innovative, robust and cost-effective solution.

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Excavation 

Excavation is the process of creating space by removing earth (soil or rock) to place a utility or structure. Several methods are available to achieve excavation. In all methods, excavation safety plays a crucial role. Some popular methods of excavation are:

Open excavation

Open excavation is a surface excavation suitable up to 6.0 meter deep. Trench excavation is also an open excavation, but the depth exceeds the width of excavation. Open excavation is mainly used for foundations, placing pipes and cables for utility services, test pits, borrow pits and road formations.

Open excavation is one of the most hazardous construction operations. Among excavation related dangers, cave-ins pose the greatest risk. Many constructions fatal accidents occurred during excavation. Therefore it’s vital to prepare a safe work method statement for carrying any excavation activity.

Purpose

Any open excavation deeper than 1.5 meter requires side protection by sloping, benching or shoring. This method statement describes the excavation safety requirements and safe work procedure for all open excavations. It summarizes suggested method of executing works safely within any constraints. This method statement offers advice and guidance to the personnel involved in this activity to:

a) Carry works in a manner that’s safe at all times;

b) Know the hazards involved in the activity;

c) Ensure controls to steer clear of hazard exposure are in place.

Use any other resources and methods not referred to in this method statement to suit the project requirement. Always execute the work safely complying with the required standard.

The sequence of activities is a repetitive process and many hazards are common to distinct sites. Include with detail, any crucial information specific to the project. Always follow the approved checklists prior to the start of the activity.

What this Method Statement covers

The scope of this document covers:

  • Safe work method and procedure for carrying open excavation works
  • Materials, equipment, and tools needed to carry out the excavation activity
  • Applicable standards throughout the execution of the project

Standards for excavation safety

  • OSHA 2226-10R 2015: Trenching and Excavation Safety (download PDF)
  • IS 3764: Indian Standard for Excavation work – Code of safety
  • IS/ISO 20474-1: Indian Standard for Earth moving machinery – Safety
  • IS 10386 (Part 8): Indian Standard for construction operation, operation, and maintenance of river valley projects (Part 8: Open excavation) – Safety code
  • IS 3696 (Part 2): Indian Standard for scaffolds and ladders – Code of safety
  • IS 4081: Indian Standard for blasting and related drilling operation – Code of safety

Personal Protective Equipment and Safety Gear

Below are the suggested PPE for excavation:

Safety Helmet
Safety Helmet

Safety Footwear
Safety Footwear

Safety Glasses
Safety Glasses

Safety Vest
Safety Vest

Safety ladder
Safety ladder

Safety barrier
Safety barrier

Safety Cone
Safety Cone

Safety Flags
Safety Flags

 

Refer standard operating procedure of PPE for further PPE details

Procedure for excavation

  • Get relevant data of subsurface soil and water table location
  • Design excavation sides and protective system based on the size of excavation and type of soil. Three popular methods to protect excavation sides are:

 

  1. Sloping the walls
Sloping walls for excavation safety
Sloping the walls for excavation safety

 

2) Bench Excavation

Bench excavation
Benching for excavation safety

3) Supported excavation by shoring up the walls with wood or metal supports

Supported excavation
Supported excavation
  • Finalize excavation and soil removal method namely mechanically or manual
  • Locate underground utilities like electric cables, Optical fiber cables (OFC), Pipeline etc. with cable detector and pipe detector.
  • Assess for a chance of chemical hazard or low oxygen levels
  • Intimate or take permission as needed from the underground utility operator
  • Get work permit for excavation work
  • Barricade the excavation area to keep vehicles, equipment, and personnel away from the excavation
  • Make proper lighting arrangements
  • Inspect the arrangements with a competent person before the start of excavation work
  • Carry manual excavation until exposure of underground utilities. Allow mechanical excavation only after exposure of underground utilities
  • Make safe access and egress arrangements for personnel and equipment at least from two sides
  • Excavation should be kept free from water. Water in an excavation can weaken the surfaces of the excavation. Dewater whenever water accumulates. If required, put essential shoring to protect persons working.
  • Carry the balance excavation with excavators

Precautions for safe excavation

  • Within 2.0 meters of excavation edge, permit only excavation equipment. Don’t allow any other equipment near excavation edge since the weight of the machines can fall trench walls.
  • Cranes should maintain a safe distance equal to the depth of excavation from the edge of the excavation
  • Deposit excavated soil along with other materials at least 0.61 meters from the edge. Place soft barricades for pedestrians at least 1.0 meter from the edge. Scaffold posts, loose materials along with any loads shall be at a distance of 1.5 times excavation depth away from the edge. Provide hard barricades for vehicles at least 2.0 meter from the edge.
  • Only authorized persons should enter the excavation
  • Keep flagman with a red flag in busy and risky locations to guide vehicular traffic
  • Keep signalman to guide equipment operation safely
  • Use blinking warning lights where the pedestrian or vehicular traffic is expected.
  • Provide additional bracing and shoring in the vicinity of the source of vibration such as Pile driving rigs to prevent slides, slips or cave-in where excavations.
  • Provide one ladder per 15 meters of length. Extend the ladder for one meter above the top of the cut
  • Prohibit persons in the path of an excavator turning bucket
  • Prohibit lone workers without a supervisor
  • Wherever presence of insects, leeches, and snakes is possible, make arrangements for repellents, fumigation and first aid as needed.
  • Carry earth work inspection daily

Common excavation safety hazards

  • Quicksand condition
  • Side walls become highly unstable following rainfall due to water content
  • Vibrations from nearby machinery, railroad, blasting, and other sources
  • The surcharge imposed by nearby buildings

Excavation safety checklist

  • Approved excavation drawing available
  • Presence of underground utilities located and marked
  • Barricades, safety signs, and lighting are in place
  • Excavation slope protection system finalized like sloping, shoring or benching
  • Entry and exit means for personnel and equipment
  • Dewatering arrangements made wherever water is expected.
  • Flagmen are positioned to guide vehicular traffic
  • Emergency rescue equipment is in place
  • Excavation permit available

Please follow the standard practice of daily checklist, weekly inspection and monthly audit for safe excavation.

Featured image source: By jasonwoodhead23 (KELLEY RAMSEY) [CC BY 2.0 ], via Wikimedia Commons

Rainwater harvesting is the activity of collecting rainwater and storing it for later use or recharge to the groundwater. The goal is to utilize the rainfall runoff going to sewer /drain /rivers. This ancient technique is increasingly recognized as a sensible way of providing potable water. For centuries the planet has relied upon rainwater harvesting to provide water for the family, landscape, and agriculture. Rainwater harvesting promotes self-sufficiency and water appreciation.

Rainwater harvesting advantages:

  • To raise the groundwater table
  • Storing water to future demands
  • Improve yield of an aquifer
  • Improve existing groundwater quality through dilution
  • Prevents saline water ingress in coast areas
  • Rain diversion into collection tanks prevents flooding and erosion.
  • Conserves energy by bypassing the energy input required to operate a centralized water system.

Three chief components of a rainwater harvesting

  1.  Collecting the rainwater
  2. Filtering collected water
  3. Recharging the filtered water through pits and bore wells

Purpose of this Method Statement

This method statement describes the procedure and resources required to do the work. Use any other resources and methods not referred to in this method statement to suit the project requirement. Always execute the work safely complying with the required standard.

This method statement summarizes suggested method of executing works safely within any constraints. This method statement offers advice and guidance to the personnel involved in this activity to:

a) Carry works in a manner that’s safe at all times;

b) Know the hazards involved in the activity;

c) Ensure controls to steer clear of hazard exposure are in place.

The sequence of activities is a repetitive process and many aspects are common to distinct sites. Include with detail, any crucial aspects specific to the project. Always follow the approved checklists prior to the start of the activity.

What this Method Statement covers

The scope of this document covers:

  • Safe work method for constructing rainwater harvesting system
  • Work procedure
  • Materials, equipment and tools needed to carry the work
  • Applicable standards throughout the execution of the project

Applicable Standards

  • IS : 15797 Indian Standard for Rooftop rainwater harvesting – Guidelines
  • Rainwater harvesting and conservation manual by CPWD, New Delhi

Materials

  • Cement
  • Bricks
  • Sand
  • Metal
  • Boulders and gravel
  • Coarse Mesh
  • Gutters
  • PVC pipes

Equipment & Tools

  • Borehole drilling equipment
  • Equipment and tools to earthwork
  • Tools for brickwork and P.C.C.

Health, Safety and Environment

Execute all activities with due regard to Health, Safety & Environment of all the workers and third parties.

  • Barricade the work area.
  • Restrict access to children from entering the borehole and recharge pit areas

Personal Protective Equipment (PPE)

Safety Helmet
Safety Helmet

Safety Footwear
Safety Footwear

Safety Glasses
Safety Glasses

Safety Gloves
Safety Gloves

Refer to the PPE Standard Operating Procedure for more details

Quality

  • Ensure that the components and materials provided are as per the necessary criteria
  • Refill materials for recharge bore and pit should be free from clay and lumps

Procedure

Rainwater harvesting system diagram
Rainwater harvesting system – Recharge pit with a bore

Delivery system

Fix gutters and drain pipes to collect roof water and transport it to recharge pit

Recharge bore

  • Drill 300 mm dia bore of 30 m deep with borewell drilling machine.
  • Fill the bore with 3 to 6 mm dia pea gravel.
  • Put a PVC casing pipe of 2.5 meter length with 3 mm perforations up to gravel layer of recharge pit. Keep 1.8 meters above ground level into the recharge pit.

Recharge pit

  • Excavate 4 m x 4 m x 2 m deep pit to construct the brickwork chamber. Keep borehole as the centre of recharge pit.
  • Construct a chamber of internal size 3 m x 3 m x 2.25 m height with 230 mm thick brick masonry. Apply waterproof plaster on the brick walls.
  • Refill bottom 750 mm thick layer with 50 to 200 mm stones. Middle 750 mm thick layer with 5 – 10 mm gravels. Top 750 mm thick layer with 1.5 to 2 mm coarse sand.
  • Fix PVC pipes above ground level to get inlet drain and overflow discharge.
  • Cover the pit with 100 mm thick R.C.C. cover slab.

Care

  • Clean the catchment area before the arrival of monsoon.
  • Cover the rooftop outlet with a coarse mesh to avoid leaves and other obstructions

References:

India water portal

Center for Science & Environment

Water4everyone

Keywords: rainwater harvesting, RWH, rainwater harvesting system, rainwater collection, collect rainwater, Safe work method statement, method statement.

Earthing or grounding purpose is to connect electrical conductors to the earth. Earthing system carries the current or electrical fields created around the structures or electrical devices to the ground.

Why do we need earthing?

  • Protect personnel against electrical hazards like electric shock and electrocution
  • Safeguards protect electrical devices, appliances, power tools, machinery etc. from current leakage
  • Damage from lightning to structures, installations and the entire electric system by using Lightning Arresters.
  • Prevents fire in the electrical systems
  • Avoids interference with communication circuits

What are earthing system types

Different types of earthing systems are available. Popular methods are:

  • Plate Earthing: A copper plate or galvanized plate is buried in an earth pit below ground level. The plate electrode connects the electrical conductors to the earth.
  • Pipe Earthing: A galvanized steel perforated pipe inside the ground connects the electrical conductors to the earth.
  • Rod Earthing: Similar to the Pipe earthing. A copper rod replaces the pipe electrode.
  • Chemical earthing: Similar to the pipe earthing. A chemical compound material replaces the charcoal and salt layers.

This article presents detailed work method statement and procedure of these earthing systems

The choice of earthing method primarily depends on:

  • Service continuity requirement at different voltages
  • Safety requirements for humans and equipment
  • Possibility of overvoltage
  • Maintenance requirements
  • Cost consideration

Purpose of this Method Statement

This method statement describes the procedure and resources required to do the work. Use any other resources and methods not referred to in this method statement to suit the project requirement. Always execute the work safely complying with the required standard.

This method statement summarizes suggested method of executing works safely within any constraints. This method statement offers advice and guidance to the personnel involved in this activity to:

a) Carry works in a manner that’s safe at all times;

b) Know the hazards involved in the activity;

c) Ensure controls to steer clear of hazard exposure are in place.

The sequence of activities is a repetitive process and many aspects are common to distinct sites. Include with detail, any crucial aspects specific to the project. Always follow the approved checklists prior to the start of the activity.

What this Method Statement covers

The scope of this document covers:

  • A safe work method for carrying out Earthing work
  • Work procedure for different types of earthing
  • Materials, equipment, and tools needed to carry out the earthing work
  • Applicable standards throughout the execution of the earthing system work

Applicable Standards

IS : 2309-1989 [Indian Standard for Protection of Buildings and Allied Structures against Lightning]

IS : 3043 Indian Standard Code of Practice for Earthing

Indian Electricity Rules 1956

Central Electricity Authority Regulations (CEAR)

Relevant regulations of the electric power supplying authority

Materials, Equipment, and Tools

  • Meggar for Earth resistivity testing
  • Welding toolkit
  • Excavator for earth pit excavation
  • Copper wire or strip
  • GI or Copperplate
  • Pipe/Rod
  • Coke/Charcoal and Salt
  • PVC Wires
  • Cement
  • Bricks
  • Funnel
  • Wire mesh

Health, Safety, and Environment

Execute all activities with due regard to Health, Safety & Environment of all the employees and third parties.

  • Assess for any underground and overhead electrical lines or some other obstructions
  • Carry the work under the strict guidance and supervision
  • Maintain adequate visibility at all times by providing appropriate lighting
  • Report immediately any anomaly found in the components

Personal Protective Equipment (PPE)

Safety Helmet
Safety Helmet

Safety Footwear
Safety Footwear

Safety Glasses
Safety Glasses

Safety Gloves
Safety Gloves

Refer to the Standard Operating Procedure (SOP) for Personal Protective Equipment (PPE) for more details.

Quality

  • Make all arrangements as per the approved shop drawing.
  • Check all materials and fittings for quality and standards compliance.
  • Store materials according to the manufacturer instructions.
  • Check all connections for cleanliness, continuity and an appropriate amount of tightness.
  • Make sure the specifications of components match with that specified in the approved shop drawing.
  • As per IS : 3043, all earth connections shall be visible for inspection.
  • Earthing system installation shall enable testing of each earth electrode.
  • Conducts all required tests and submit the results for approval.

Procedure for plate earthing

Plate earthing diagram
Plate electrode earthing system
  • Earth pit: Excavate and make an earth pit of size 900 mm x 900 mm x minimum 3.0 meter deep. Level the bottom surface.
  • Plate electrode: Use GI plate of minimum size 600 Mm x 600 Mm x 6.3 mm thickness. In case of a Copperplate, a minimum thickness of 3.15 mm can be used.
  • Earthing connection: Fix two numbers of 50 mm x 6 mm GI strips to GI plate firmly with GI nut, check nut, bolt, and washer with each strip fixed to GI plate at two locations. Weld the GI strips to GI plate. Join the two strips at the top with a GI strip of the same size. Any loose earthing connection with the earth plate will have an adverse effect on the electrode system resistivity.
  • Water connection: Fix a 25 mm diameter GI pipe attached at the top with a funnel covered with wire mesh. Water poured through this pipe will keep the area surrounding the earth plate moistened.
  • Backfill the excavated pit with soil free of stones and lumps.
  • Inspection chamber: Construct brick chamber of size 450 x 450 x 450 mm with 100 mm thick brick walls over a P.C.C. layer. Keep 100 mm of the chamber above ground level. Cover the top with a cast iron (CI) cover.
  • Follow the approved design and drawing for fixing and laying of earth wires or GI/copper strips between the earth electrode and the electrical room.

Suggested item description for G.I. Plate earthing:

Supply and erection of G.I. plate earthing with earth plate size 600X600X6.3 mm, at least 3.0 meter below ground with double G.I. strip 50 x 6 mm bolted to the plate, 25 mm dia GI pipe with wire mesh funnel for watering, 230 brick masonry inspection chamber of size 450 mm x 450 mm x 450 mm, C.I. cover 300mm x 300mm (10 Kg) complete with necessary length of double G.I. earth wire no. 6 SWG bolted with lug to the plate and covered in 12 mm dia G.I. pipe 3.0 meter long complete connected to the nearest switchgear with end socket and duly tested by earth tester and recording the results. Excavation work is included in the scope of the contractor. Job to be executed as per approved drawing and technical specifications and as directed by Engineer Incharge complete.

Procedure for pipe or rod electrode earthing

Pipe electrode earthing
Pipe earthing system
  • Make a borehole of 500 mm diameter and 3.5 meters deep or as per the approved design and drawing.
  • Lower the Pipe electrode made of a 65 mm diameter GI perforated pipe of 3.0-meter length attached at the top with a funnel covered with wire mesh. A G.I. strip is fixed to the electrode to act as an earthing connection. For rod earthing, a copper rod of required diameter is used in place of the pipe.
  • Fill the annular space between the electrode and borehole walls with alternating layers of coke or charcoal and common salt.
  • Inspection chamber: Construct brick chamber of size 450 x 450 x 450 mm with 100 mm thick brick walls over a P.C.C. layer. Keep 100 mm of the chamber above ground level. Cover the top with a cast iron (CI) cover.
  • Follow the approved design and drawing for fixing and laying of earth wires or GI/copper strips between the earth electrode and the electrical room.

Suggested item description for G.I. Pipe electrode earthing:

Supply and erection of G.I. earth pipe electrode 65 mm diameter, at least 3.0 meter below ground with 40 Kg alternate layers of charcoal and salt with and with wire mesh funnel for watering, 230 brick masonry chamber (450 mm x 450 mm x 450 mm), C.I. cover 300mm x 300mm (10 Kg) complete with necessary length of double G.I. earth wire no. 6 SWG bolted with lug to the plate and covered in 12 mm dia G.I. pipe 3.0 meter long complete connected to the nearest switchgear with end socket and duly tested by earth tester and recording the results. Excavation work and making borehole are included in the scope of the contractor. Job to be executed as per approved drawing and technical specifications and as directed by Engineer Incharge complete.

Procedure for chemical earthing

Chemical earthing procedure is similar to the pipe electrode system. A chemical compound is used in place of alternate charcoal or coke and salt backfill material. The chemical compound eliminates the necessity of moistening the backfill by water pouring as in the case of conventional pipe electrode system. Due to this reason, chemical earthing is free of maintenance.

Cuplock scaffolding is among the most well-known scaffolding systems. It’s modular, easy to set up and provides high safety working to workers. This method statement pertains to the cuplock scaffolding system.

A scaffold is a temporary stage used for working from on a construction site. It is required when the work that has to be done is at an elevated location. Several types of scaffolding systems are available for construction. A few of the scaffolding systems are:

  • Single scaffolding
  • Double scaffolding
  • Tubular steel scaffolding
  • Cuplock scaffolding

Purpose

This method statement describes the procedure and resources required to do the work. Use any other resources and methods not referred to in this method statement to suit the project requirement. Always execute the work safely complying with the required standard.

This method statement summarizes suggested method of executing works safely within any constraints. This method statement offers advice and guidance to the personnel involved in this activity to:

a) Carry works in a manner that’s safe at all times;

b) Know the hazards involved in the activity;

c) Ensure controls to steer clear of hazard exposure are in place.

The sequence of activities is a repetitive process and many aspects are common to distinct sites. Include with detail, any crucial aspects specific to the project. Always follow the approved checklists prior to the start of the activity.

What this Method Statement covers

The scope of this document covers:

  • A safe work method for carrying Cuplock Scaffolding system
  • Scaffolding work procedure
  • Materials, equipment, and tools needed to carry out the Scaffolding activity
  • Applicable standards throughout the execution of the project

Applicable Standards for Cuplock Scaffolding

  • OSHA 3150: Scaffolding
  • IS: 2750 : 1964 – Steel scaffolding
  • IS 4014 : 1967 Part 2 – Steel tubular scaffolding – safety regulations for scaffolding

Materials required for Cuplock Scaffolding

  • Standards (Verticals)
  • Ledgers (Horizontals)
  • Transoms
  • Bracings
  • Brackets
  • Tie bars
  • Universal Jack
  • Socket Base
  • Steel planks
  • Clamps and Adapters

Equipment and tools used for Cuplock Scaffolding

  • Tape measure
  • Spanner set
  • Hammer
  • Other equipment for material handling and shifting as required

Health, Safety, and Environment

Execute all activities with due regard to Health, Safety & Environment of all the employees and third parties.

  • Assess for any underground and overhead electrical lines or some other obstructions
  • Safety nets shall be present whenever there’s work to be done at or above a height of 2.5 meters.
  • Each of scaffolding things must be passed with caution and not thrown.
  • Assess site prior to scaffolding erection to ensure appropriate load support without a settlement.
  • Carry the work under the strict guidance and supervision
  • Maintain adequate visibility at all times by providing appropriate lighting

Personal Protective Equipment (PPE)

Safety Helmet
Safety Helmet
Safety Footwear
Safety Footwear
Safety Glasses
Safety Glasses

 

 

 

 

Safety harness
Safety harness
Safety Vest
Safety Vest
Safety Gloves
Safety Gloves

 

 

 

 

You may be interested in reading:  Standard Operating Procedure (SOP) for Personal Protective Equipment (PPE)

Quality

  • Inspect all scaffold components for any visible defects like cracks, corrosion etc.
  • Scaffolding components from various makers should not be combined.

Procedure

  • Place the standards (verticals) on base plates above level and firm strata that’s capable to support the load without a settlement
  • Erect the initial lift. Fasten all connections securely before erecting following lifts
  • All platforms must be planked entirely with a minimum width of 460 mm
  • Install guardrails on all open sides
  • Provide adequate accessibility for example ladders, stairway, ramps and walkways as required.
  • Install debris nets to defend persons from debris and some other falling objects

References:

https://www.osha.gov/Publications/OSHA3150/osha3150.html

https://www.osha.gov/pls/publications/publication.athruz?pType=Industry&pID=188

Roof Waterproofing methods

The wide variety of terrace waterproofing methods often makes it difficult to select a right waterproofing system. Some of the deciding factors are insulation requirements; availability of proper slope; available contractors preference; condition of a structure. Here are some popular waterproof methods and their procedures.

1. Integral waterproofing

Unlike methods that can be applied after concrete pour, Integral waterproofing makes the concrete impervious by adding chemical admixtures during the concrete making. There are three types of integral waterproofing systems based on the process by which the admixture achieves waterproofing.

  • Hydrophobic admixture based: Cement contains calcium ions. The water-repellent or Hydrophobic admixtures like Sika 1+ reacts with the calcium ions to form a water-repellent within the pores and blocks the pores. This process makes the concrete less absorbent of water and prevents water ingress.
  • Densifying admixture based: Concrete can be produced with a low water-cement ratio by using a densifying admixture making a less permeable and low absorption concrete. This process makes the concrete waterproof.
  • Crystalline admixture based: The crystalline admixtures forms crystalline composites and blocks the capillary pores. This process makes the concrete waterproof.

The decision to go with the integral waterproofing system and choosing the admixtures, procurement of the products etc. need to be finalized before actual pouring of concrete. Many a time this may indeed knock off few months from the project completion.

Procedure

  • Design the concrete mix with the proposed integral waterproofing admixture to determine optimum dosage.
  • Add the admixture with the water by means of a calibrated dispenser to the concrete ingredients.
  • Lay the concrete and cure well similar to any other concrete.

Advantages

  • Damage to the surface will not alter waterproofing properties. Whereas, in all other kinds of waterproof coatings, utmost care is required not to damage the protective coating.
  • Does not require a separate schedule for waterproofing activity resulting in savings to project completion time.

2.   Brickbat Coba waterproofing

The brickbat coba is used for waterproofing of RCC flat roofs. It consists of putting brickbats on roofs maintaining a proper slope and then grouting the same with mortar mixed with waterproofing compounds. This method is now out of favor and many choose superior alternative methods and better products from leading providers.

Procedure

  • Surface preparation:  Thoroughly clean the surface free of loose materials and dust
  • Slurry or mortar preparation:  Blend the cement with waterproofing compound (if in powder form) or water mixed with waterproofing compound (if in liquid form) and prepare the mortar. In the entire Brickbat Coba procedure, wherever slurry or mortar is used, it shall be used mixed with waterproofing compound only
  • First layer (sub-base):  Dampen the surface and apply slurry with brush including in all joints
  • Second layer (base):  Apply 25 mm thick cement mortar in 1 cement : 4 sand ratio while the first coat is still green.
  • Third layer (brickbat):  Place with hand 40 to 75 mm thick brickbats with 15 mm thick mortar packed below the brickbat over the second layer. Leave suitable gaps between brickbats. Cure the surface for 24 hours. After 24 hours curing, apply slurry and fill the gaps between brickbats with 1 cement : 4 mortar.
  • Fourth layer (Protective layer):  Apply 20 mm thick cement mortar in 1 cement : 4 sand ratio while the third layer is still green. Finish the surface smooth with cement slurry.
  • Test the treated surface by making bunds with cement mortar and flooding the water. Keep the water for a minimum of two weeks. Observe for any leaks.

Advantages

  • Maintaining slope is easy
  • Workforce easily available particularly in the interior areas
  • Provides heat insulation
  • High wear and tear resistance
  • Cracks will not occur easily because of temperature variations. This will, in turn, prevents leakages. Putting china chips on top can further prevent cracks formation due to thermal variation.

3.   Cementitious coating waterproofing

Cementitious waterproofing system is cement based modified with acrylic polymers. While the cementitious materials provide the tensile strength, polymers improve elastic and adhesion properties. This makes the coating elastic and prevents water ingress to make it suitable for a waterproofing system. Cementitious coatings are popular due to their ease of application and easy availability at any building product stores. In addition to waterproofing, these coatings can also enhance the durability of an existing surface.

Procedure

  • Clean the surface thoroughly free of loose particles, dirt, and oil traces.
  • Mix the materials well as per manufacturer specification. The product comes in two components and requires site mixing making it a thin liquid.
  • Wet the surface to a saturated surface dry condition.
  • Apply the mix over the surface with brush or roller maintaining uniform thickness as specified.

Check out this video of cementitious waterproofing by BASF

 

Advantages

  • Good bonding with the existing surface
  • Easy application
  • Availability of materials at most of the building material stores
  • High wear and tear resistance

4.  Polymer modified Bitumen membrane waterproofing

Modified bitumen membranes are made of bitumen blended with polymers and reinforced with polyester. These are also known as APP (Atactic-Polypropylene) modified bitumen membrane. The resultant membrane offers flexibility and heat resistance in addition to preventing water ingress. These properties of modified bitumen membrane make it suitable as a waterproof coating. They are available in a roll form and can be easily applied by the torch-on method.

Procedure

  • Surface Preparation: Clean the surface thoroughly free from loose materials, dust, and oil. Surface cleaning plays a vital role in all membrane based waterproofing coating systems to ensure proper adhesion of the membrane with the base surface receiving waterproofing coating.
  • Primary coat: Apply a primary coat to prime the surface as per manufacturer’s specification. Solvent-based or water-based primers are suitable for bitumen membranes.
  • Unroll the membrane sheets. Check for the correct alignment and adjust the sheets wherever required.
  • Heat with a torch the burn-off film present at the underside face of the membrane. Now the membrane is ready for bonding with the underlying concrete surface.
  • Press the membrane firmly ensuring proper bonding with the concrete surface. Additional care should be taken for overlaps, edges and at angles to ensure proper bonding.

Advantages

  • High resistance to heat and temperature changes.
  • Highly elastic. Prevents crack forming
  • Very low water absorption
  • Durable: Long lasting material

5. Polyurethane liquid membrane waterproofing

Polyurethane (popularly known as PU) coating is highly elastic with excellent heat resistance in addition to preventing water ingress. These properties of polyurethane make it suitable as a waterproof coating. The application of the coating is relatively easy. They are available as a single component and can be easily applied with brush or roller.

Procedure

  • Surface Preparation: Clean the surface thoroughly free from loose materials, dust, and oil. Sprinkle some water on the surface and observe for any presence of oil contamination. If require using suitable solvents to removed oil traces. Other materials can be removed by grinding and other by other mechanical means. Surface cleaning plays a vital role in all membrane based waterproofing coating systems to ensure proper adhesion of the membrane with the base surface receiving waterproofing coating.
  • Crack filling: Clean all cracks and joints. Fill the cracks with a sealant approved by the polyurethane system manufacturer to ensure compatibility.
  • Primary coat: Apply a primary coat to prime the surface as per manufacturer’s specification.
  • First coat (Basecoat): Stir the liquid polyurethane compound slowly and thoroughly for around 2 minutes. Apply evenly with a brush or roller.
  • Sand: Sprinkle quartz sand on top of base coat.
  • Topcoat: Apply one more coat of polyurethane similar to the base coat.

 

Check out this video of a liquid membrane by Sika

 

Advantages

  • High resistance to heat and temperature changes.
  • Highly elastic. Prevents crack forming
  • UV resistant

6.  PVC membrane waterproofing

PVC (polyvinyl chloride) membrane is a plasticized membrane reinforced with polyester mesh or glass fiber. The resultant membrane is highly flexible with good tear resistance and impermeable qualities.

Procedure

  • Surface Preparation: Clean the surface thoroughly free from loose materials, dust, and oil.
  • Crack filling: Clean all cracks and joints. Fill the cracks with a sealant approved by the PVC membrane manufacturer. Apply reinforcing tape to joints and cracks.
  • Primary coat: Apply a primary coat to prime the surface as per manufacturer’s specification.
  • Unroll the membrane sheets without stretch. Check for the correct alignment and adjust the sheets wherever required.
  • Heat with a torch the underside face of the membrane to softening point. Now the membrane is ready for bonding with the underlying concrete surface.
  • Press the membrane firmly ensuring proper bonding with the concrete surface. Additional care should be taken for overlaps, edges and at angles to ensure proper bonding.
  • Finish the surface with Aluminium paint (for non-foot traffic area) and with protective screed (for the foot-traffic area).

Check out this video of PVC waterproofing membrane laying by TexsaTV

 

 

Advantages

  • Insensitive to thermal variations
  • High durability and long life
  • Widely used and proven system

7. EPDM membrane or Synthetic rubber waterproofing

Ethylene, propylene, diene terpolymer (EPDM) is an elastomeric compound or synthetic rubber compound and is one of the most effective waterproofing systems. The membrane is highly durable. EPDM system is suitable for a wide variety of waterproofing applications like roofs, pond lining etc.

Procedure

  • Surface Preparation: Clean the surface smooth thoroughly free from loose materials, dust, and oil. Make the surface dry by removing any water present. Get rid of any rough surfaces and unevenness to avoid any damage to EPDM.
  • Crack filling: Clean all cracks and joints. Fill the cracks and any voids with an approved material by the EPDM membrane manufacturer.
  • Unroll the membrane sheets without stretch. Check for the correct alignment and adjust the sheets wherever required.
  • Fold back the membrane and apply adhesive to both EPDM underside and on the concrete surface with roller or sprayer.
  • Roll back the membrane onto the adhesive coated roof surface.
  • Press the membrane firmly ensuring proper bonding with the concrete surface. Additional care should be taken for overlaps, edges, flashings, and roof drains to ensure proper bonding.

 

Check out this video of EPDM laying by Firestone

 

Advantages

  • UV resistance
  • Can withstand thermal variations
  • Extremely flexible.
  • Durability
  • Impact and tear resistant
  • Widely used and proven system

Looking for waterproofing contractors? Find here

What is A Topographic Survey?

A topographic survey is an Engineering survey to understand and analyze the ground features along the proposed alignment. By applying mathematical principles to the Survey data, existing or future horizontal and vertical position will be determined. The main objective of topographic survey for a road is to create a digital terrain model (DTM) by acquiring terrain data. Survey activities include road alignment, fixing center line of road, providing permanent grid lines and benchmarks as per the applicable standards.

The topographic survey helps the engineers to:

  • prepare alignment drawings
  • prepare cross-sectional profiles
  • identify existing structures in the proposed road alignment
  • finalize requirement of bridges, culverts, diversions etc.
  • plan land acquisition requirements
  • establish control of locations
  • establish elevation difference between fixed points
  • identify the presence of underground utilities like pipelines, electrical cables etc.

Purpose of this Method Statement

This method statement describes the procedure and resources required to do the work. Use any other resources and methods not referred to in this method statement to suit the project requirement. Always execute the work safely complying with the required standard.

This method statement summarizes suggested method of executing works safely within any constraints. This method statement offers advice and guidance to the personnel involved in this activity to:

  • Carry works in a manner that’s safe at all times;
  • Know the hazards involved in the activity;
  • Ensure controls to steer clear of hazard exposure are in place.

The sequence of activities is a repetitive process and many aspects are common to distinct sites. Include with detail, any crucial aspects specific to the project. Always follow the approved checklists prior to the start of the activity.

What this Method Statement covers

The scope of this document covers

  • A safe work method for performing a topographic survey
  • Topographic survey for road work procedure
  • Materials, equipment, and tools needed to carry out the activity
  • Applicable standards to execute the work

Applicable Standards

  • Specifications for Road and Bridge Works published by Indian Roads Congress
  • IRC:SP : 19-2001 : Manual for Survey, Investigation, and Preparation of Road Projects

Equipment & Tools for topographic survey

  • Total station with appropriate software
  • Electronic distance measurement (EDM) reflectors
  • Differential Global Positioning System (DGPS)
  • Auto level and level staff
  • Measuring tape
  • Range poles
  • Level Rods
  • Digging Tools
  • Pegs and nails
  • Paint and paint application tools

Health, Safety, and Environment

Execute all activities with due regard to Health, Safety & Environment of all the employees and third parties.

  • All persons involved in the survey activity must wear reflective vests and identity cards
  • Provide adequate flaggers, warning taps and safety cones as required
  • Make the necessary arrangement to provide drinking water
  • Provide vehicle and cell phones as required
  • DO NOT expose telescope to the sun
  • DO NOT carry instrument along with stand
  • DO NOT keep battery inside the instrument when the instrument is inside the box

Personal Protective Equipment (PPE)

Safety Helmet
Safety Helmet

Safety Footwear
Safety Footwear

Safety Vest
Safety Vest

Safety Glasses
Safety Glasses

Safety Cone
Safety Cone

Safety Flags
Safety Flags

 

Find more details about Personal Protective Equipment (PPE) here.

Quality

  • Ensure valid calibration certificates for auto level and total stations through authorized agencies.
  • Follow approved survey checklist
  • Non-closures of own measurements and combined with the previous surveys shall meet the specified requirements.
  • The data should be in a form amenable to digital terrain model (DTM) commonly used by highway design software like MXROAD SuiteAutoCAD Civil 3D or equivalent).

Procedure for Topographic Survey

  • Collect Great Trigonometrical Survey (GTS) Bench Mark data along the road sections
  • All reference pillars shall be of M20 grade of size 20 cm x 20 cm x 45 cm height. Fix a 10 mm dia steel bar inside the concrete pillar. Fix the pillars on a firm ground embedded in M15 grade PCC up to a depth of 30 cm and 5 cm wide all around. Paint the rest 15 cm of pillar above the ground with yellow color paint.
  • All control point pillars namely horizontal control points and the benchmarks shall be of an M20 grade of size 20 cm x 20 cm x 60 cm height. Fix a 10 mm dia steel bar inside the concrete pillar. Fix the pillars on a firm ground embedded in M15 grade PCC up to a depth of 45 cm and 5 cm wide all around. Paint the rest 15 cm of pillar above the ground with yellow color paint.
  • Fix horizontal control points using DGPS instrument at every 5 km.
  • Establish Bench Mark (BM) stations at every 250 meters interval. Use double run leveling method with digital auto levels.
  • Fix all cardinal points like horizontal intersection points (HIP), center points and transit points etc. with a pair of reference pillars fixed on either side of the center line at safe places within the ROW.
  • Take spot levels at every 25 m interval for cross-sectional Topographic survey
  • Establish reference center line and mark the same by nails on the ground. Mark by paint for the existing road surface. Take the spot levels at every 25 m interval along the center line for longitudinal Topographic survey
  • Other physical features

Capture details of all existing structures like

  • major bridges, minor bridges, culverts
  • utilities present underground or overhead – electrical lines, gas pipelines, OFC  etc.
  • presence of water bodies
  • religious structures
  • Any other structure of significance

The details shall include location, chainage, invert level etc.

What is Shotcrete or Gunite or Spray concrete

Shotcrete and Gunite are one and the same. Indian and American standards term this concrete as shotcrete. European standards term the same as sprayed concrete. IS 9012 defines shotcrete as “mortar or concrete (conveyed through a hose) and pneumatically projected at high velocity onto a surface.

Purpose of this Method Statement

This method statement describes the procedure and resources required to do the work. Use any other resources and methods not referred to in this method statement to suit the project requirement. Always execute the work safely complying with the required standard.

This method statement summarizes suggested method of executing works safely within any constraints. This method statement offers advice and guidance to the personnel involved in this activity to:

a) Carry works in a manner that’s safe at all times;

b) Know the hazards involved in the activity;

c) Ensure controls to steer clear of hazard exposure are in place.

The sequence of activities is a repetitive process and many aspects are common to distinct sites. Include with detail, any crucial aspects specific to the project. Always follow the approved checklists prior to the start of the activity.

What this Method Statement covers

The scope of this document covers:

  • Safe work method for carrying the work
  • Work procedure
  • Materials, equipment, and tools needed to lay shotcrete or gunite
  • Applicable standards throughout the execution of the project

Applicable Standards

IS : 9012: Indian Standard Recommended Practice for Shotcreting

Materials for Shotcrete

  • Cement: Portland slag cement or Portland pozzolana cement
  • Fine aggregate: Zone II and Zone III grading of IS 383-1970
  • Coarse aggregate: 10 mm size
  • Water: A water cement ratio of 0.4 to 0.5
  • Reinforcement: Reinforcing bars or welded wire fabric

Equipment & Tools for shotcrete

  • Batching and mixing equipment
  • Delivery equipment like Shotcrete gun, nozzle, pump
  • Air supply arrangement
  • Hosepipe
  • Water supply arrangement

More details

Health, Safety, and Environment

Execute all activities with due regard to Health, Safety & Environment of all the employees and third parties.

  • Perform safety checks on all pressurized lines before usage
  • Shotcrete spray from the nozzle is potentially hazardous if not handled cautiously
  • Maintain adequate visibility at all times by providing appropriate lighting
  • Safety clamp all material hoses and airlines
  • The nozzle should not be casually put down until pressure is offline.
  • Review Material Safety Data Sheets (MSDS) for all materials in use.
  • Carry the work under the strict guidance and supervision

Personal Protective Equipment (PPE)

Below are the suggested PPE for shotcrete works:

Safety Helmet
Safety Helmet

Safety Footwear
Safety Footwear

Safety Glasses
Safety Glasses

Safety Ear Protection
Safety Ear Protection

Safety Gloves
Safety Gloves

Safety Vest
Safety Vest

 

Find more details about Personal Protective Equipment (PPE) here.

Quality

  • Compressive strength: cubes or cores shall be taken from the panel of size 75 x 75 cm. Maintain a thickness same as that of the structure but not less than 7.5cm. Alternatively, cores can be taken having a minimum diameter of 7.5 cm and a length-diameter ratio of at least 1.
  • Other materials: Same testing requirements as cast-in-situ concrete testing
  • Slump tests
  • Maintenance of Batch records with details of contents in each batch

Procedure for shotcrete or gunite

  • Thoroughly clean all surfaces to receive shotcrete by removing loose materials and dust and pressure washing. Dampen the surface to a saturated surface dry condition.
  • Fix wire mesh to the concrete surface. The steel wire mesh has to be placed in position keeping the mesh within 10-15 mm from the surface. Suitable fixing pins are to be inserted to keep the mesh in proper position and to ensure that the weld mesh is not disturbed during concrete spray.
  • Prepare a cement/water mix. Pour this mix into Pump hose for lubrication before starting to pump the production mixture.
  • When the pumped mixture reaches the nozzle, turn on the compressed air.
  • Apply shotcrete evenly to targeted surfaces. Built-up the desired thickness of shotcrete in layers of about 30 mm thick each. The presence of voids can be found by hollow hammering sound after the shotcrete has attained strength after around 3 days.
  • Clean all discharge lines with a through water flush

Shotcrete or gunite item description for repair work

Apply shotcrete including removal of defective concrete; cleaning the surface thoroughly; designing the mix with water cement ratio ranging from 0.35 to 0.50, density of gunite not less than 2000 kg/cum, strength not less than 25 Mpa; preparing the mix comprising of cement, sand, coarse aggregates, water and quick setting compound in the specified proportions; applying the shotcrete mixture mechanically with compressed air under pressure;

The equipment that essentially needs to be worn while performing a certain activity to ensure the safety of oneself and others around is known as Personal Protective Equipment (PPE).

Purpose of Personal Protective Equipment (PPE)

Wearing necessary Personal Protective Equipment (or PPE in short) is one of the most and basic safety practice applicable to all work methods in any project. This Standard Operating Procedure is to provide a favorable environment to protect each and every person against the health and safety risks at work.

Hard Hats

Safety Helmet
Safety Helmet

Safety helmets for head protection shall be used by all personnel at work area at all times. The safety helmets shall be of ISI approved only. It shall be the organization’s policy to follow ‘no helmet, no work’ rule. Applicable Indian Standard for safety helmet is IS 2925:1984 and only the approved makes shall be used. The safety helmets will appear in most of the method statements’ personal protective equipment (PPE) section.

Footwear

Safety Footwear
Safety Footwear

Protective footwear or safety shoes are nearly as crucial as protective headgear. Safety shoes prevent any potential hazards against sharp objects, live electric wires, slippery surfaces etc. Must be used by all persons at work at all times. Applicable Indian Standard for protective footwear is IS 6519:1971 and IS 5852:2004 [Steel toe safety shoes]. Only the approved makes of safety shoes shall be used.

Goggles

Safety Glasses
Safety Glasses

Safety goggles protect the eyes from particulates, dust, chemicals, water etc. Must be used in areas where dust is present in the work area; generation of dust occurs like in cutting & grinding works, carpentry etc.; the possibility of smoke or chemical fumes (example: Shotcrete or Gunite work). Applicable Indian Standard for protective eyewear is IS 5983:1980 and only the approved makes shall be used.

Reflective Vests

Safety Vest
Safety Vest

Reflective waists make the persons at work more visible from a distance. Helps in improving the visibility of a person’s presence at work.  Must be used by all persons at work at all times (example: topographic survey for a road). Applicable Indian Standard for the reflective vest is IS 15809:2008 and only the approved makes shall be used.

Gloves

Safety Gloves
Safety Gloves

Persons that need to handle objects that can be hazardous if not handled carefully must wear protective gloves. As a good practice, any person required to touch a material that forms part of a permanent structure must do so by wearing protective gloves. Applicable Indian Standard for protective gloves is IS 4770:1991 and only the approved makes shall be used.

Safety Harness

Safety Vest
Safety Vest

Fall protection arrangements must be provided for working at elevations of 6 feet and above. Persons working at 6 feet and above height must wear a safety harness (Example: Scaffolding work). Securely attach the harness to an anchor point. Applicable Indian Standard for safety harness is IS 3521:1999 and only the approved makes shall be used.

Hearing Protection

Safety Ear Protection
Safety Ear Protection

All persons with possibility of exposure to noise levels in excess of 85 decibels (A) 8-hour Leg must wear hearing protection equipment like earmuffs or earplugs. Workers involved in the usage of heavy equipment like Diaphragm wall construction or drilling require hearing protection. Avoiding such measures may cause hearing complications in short term or long term. Applicable Indian Standard for protective gloves is IS 9167:1979 and only the approved makes shall be used.

Respiratory Protection

Respiratory Protection
Respiratory Protection

Based on the requirement as per risk assessment, anyone working in areas that are dusty, consist of harmful gases, or are in a low or high air pressure area that is not abundant in oxygen shall be provided with suitable respiratory equipment to allow normal respiration of the person. Applicable Indian Standard for protective gloves is IS 9623:1980 and only the approved makes shall be used.

Life Buoyancy Aids

Life Jackets
Life Jackets

Each person must be wearing life jackets that are securely tied whenever they are working or traveling over water. Applicable Indian Standard for protective gloves is IS 6685:2009 and only the approved makes shall be used.

Safety Manager/Officer shall provide appropriate training to all persons in the proper usage of PPE.

Materials manager shall ensure sufficient Personal Protective Equipment (PPE) stock is available at all times.