c09_construction_hazards_and_controls_COMPLETE

Question 1

Range of construction activities

Answer 1

Site clearanceDemolition and dismantlingExcavationLoading, unloading and storage of materials Vehicle movements FabricationDecorationCleaningSite servicesLandscaping

Question 2

Particular construction issues

Answer 2

Transitory nature of workers Temporary nature of construction activities and the constantly changing workplaceTime pressure Weather conditions Literacy, numeracy and language

Question 3

Processes for risk management, provision of information and the cooperation and coordination of duty holders are managed through clearly defined roles and responsibilities, and the use of two key documents –

Answer 3

the health and safety plan and the health and safety file

Question 4

Five parties have specific duties under the CDM Regulations and each are allocated specific duties. The duty holders may be organisations rather than individuals, and may also be within the same organisation. The duty holders are:

Answer 4

(1) Client (2) Designer(s) (3) CDM Co-ordinator (CDMC) (4) Principal contractor (5) Contractors (and self-employed persons).

Question 5

A project is notifiable if the construction phase is:

Answer 5

(a) longer than 30 days (b) involves more than 500 person days of construction work.

Question 6

Health and safety plan contents

Answer 6

Project description Management of works Arrangements for controlling significant site risks The health and safety file

Question 7

The health and safety file should include the following information, where this may be relevant to the health and safety of any future construction work.

Answer 7

(a) A brief description of the work carried out. (b) Residual hazards and how they have been dealt with, for example: surveys or other information concerning asbestos, contaminated land, or buried services. (c) Key structural principles incorporated in the design of the structure, for example: bracing, and safe working loads for floors and roofs, particularly where these may preclude placing scaffolding or heavy machinery there. (d) Any hazards associated with the materials used, for example: hazardous substances, lead paint, special coatings which should not be burned off. (e) Information regarding the removal or dismantling of installed plant and equipment, such as lifting arrangements. (f) Health and safety information about equipment provided for cleaning or maintaining the structure. (g) The nature, location and markings of significant services, including fire fighting services. (h) Information and as-built drawings of the structure, its plant and equipment, for example: the means of safe access to and from service voids fire doors and compartmentation.

Question 8

CDM overview

Answer 8

Part 2: General management duties applying to construction projects Part 3: Additional duties where project is notifiable Part 4: Duties relating to health and safety on construction sites

Question 9

Part 2: General management duties applying to construction projects

Answer 9

Regulation 4: CompetenceRegulation 5: Co-operation Regulation 6: Co-ordinationRegulation 7: General principles of prevention Regulation 8: Election by clients Regulation 9: Client’s duty in relation to arrangements for managing projects Regulation 10: Client’s duty in relation to information Regulation 11: Duties of designers Regulation 12: Designs prepared or modified outside Great Britain Regulation 13: Duties of contractors

Question 10

Part 3: Additional duties where project is notifiable

Answer 10

Regulation 14: Appointments by the client where a project is notifiableRegulation 15: Client’s duty in relation to information where a project is notifiable Regulation 16: The client’s duty in relation to the start of the construction phase where a project is notifiable Regulation 17: The client’s duty in relation to the health and safety file Regulation 18: Additional duties of designers Regulation 19: Additional duties of contractors Regulation 20: General duties of CDM co-ordinators (CDMC) Regulation 21: Notification of project by the CDM co-ordinator Regulation 22: Duties of the principal contractor Regulation 23: The principal contractor’s duty in relation to the construction phase plan Regulation 24: The principal contractor’s duty in relation to co-operation and consultation with workers

Question 11

Part 4: Duties relating to health and safety on construction sites

Answer 11

Regulation 26: Safe places of work Regulation 27: Good order and site security Regulation 28: Stability of structures Regulation 29: Demolition or dismantling Regulation 30: Explosives Regulation 31: Excavations Regulation 32: Cofferdams and caissons Regulation 33: Reports of inspections Regulation 34: Energy distribution installations Regulation 35: Prevention of drowning Regulation 36: Traffic routes Regulation 37: Vehicles Regulation 38: Prevention of risk from fire, etc. Regulation 39: Emergency proceduresRegulation 40: Emergency routes and exits Regulation 41: Fire detection and fire-fighting Regulation 42: Fresh air Regulation 43: Temperature and weather protection Regulation 44: Lighting

Question 12

A property development company has acquired a former Victorian grain warehouse, abandoned for the past twenty years, to convert into luxury apartments. A Principal Contractor has been appointed for the entire project which involves total removal of the building internals followed by construction of the apartments within the building shell. The demolition work is sub-contracted to a specialist company. (a) Under the Construction (Design and Management) Regulations 2007 (CDM): (i) outline the specific duties of the Principal Contractor with regard to the demolition phase of the project. Your answer should exclude requirements to check on client’s duties. 7 marks (ii) identify additional duties specific to demolition under CDM. 3 marks (b) Outline the content of the Pre-Construction Information that will be of specific interest to the demolition contractor. 10 marks

Answer 12

(a) (i) CDM Regulations 22 to 24 refer specifically to the duties placed upon the Principal Contractor and include:  the development of a construction phase plan, providing the demolition contractor with a copy of the plan relating to demolition, informing them of the minimum time for planning and preparation before beginning work and ensuring that he/she is competent to manage a demolition sub contract  planning, managing and monitoring the demolition phase to ensure it is carried out without risks to health and safety  ensuring that information relating to their activities is provided to the demolition contractor and ensuring safe working and co-ordination between them and other subcontractors  ensuring that welfare facilities suitable for demolition work, such as decontamination units and showers, are provided  taking steps to prevent access to the construction site by unauthorised persons  identifying the information relating to the demolition activity required by the CDM coordinator for inclusion in the health and safety file  ensuring that all contract and sub-contract employees are given site induction and any further information and training they might need in relation to health and safety  consulting with employees or their representatives on health and safety issues. (a) (ii) The additional duties in the Regulations specific to demolition are found in Regulation 29. They require that the demolition of a structure should be planned and carried out in such a manner as to prevent danger or where it is not practical to prevent it, to reduce the danger to as low a level as is reasonably practicable. The arrangements for carrying out the demolition work should be recorded in writing before the work begins. (b) Information of interest would include:  location of site and buried services  details of hazardous and flammable substances stored on the site  possible contamination of the ground or drains  the location of other hazards such as asbestos  the possible presence of anthrax contaminated plaster  the presence of any hazardous machinery or equipment that has been left in the building  details of weaknesses in the structure, such as fragile roofs or the presence of rot  ground conditions such as possible instability and the existence of culverts  information on the previous use of the land  means of access to the site and traffic routes particularly those for the removal of waste  the proximity of neighbours  copies of the original building plans if available  details of any restrictions on the hours of work.

Question 13

(a) Outline the duties of designers under the Construction (Design and Management) Regulations 2007 (CDM 2007). 6 marks (b) Outline examples of the ways in which designers can affect the health and safety performance of a construction project. 4 marks (c) A contractor is to be engaged to demolish a disused factory. Outline examples of the information that the client should provide to the tendering contractors to fulfil their duty under CDM 2007. 10 marks

Answer 13

(a) Under the Construction (Design and Management) Regulations 2007, a designer has a duty:  to avoid in his designs foreseeable risks to the health and safety of any person carrying out the construction work, involved in future maintenance or cleaning of the structure or using the structure as a workplace the Workplace Regulations contain provisions relating to the design of materials used in the construction of a workplace  to provide with his design sufficient information to assist the client, other designers and contractors to comply with their duties under the CDM Regulations  to provide information as required for the Health and Safety file and to check that the client is aware of his duties under the Regulations. In the case of a notifiable project, the designer also has a duty to ensure that the required notification has been made. Designers also have a duty to ensure they have the necessary competence for the duties that they undertake. (b) Examples of designers effects include:  specifying safer materials from a COSHH perspective  reducing manual handling risks by minimising block size  promoting safer construction methods, for example, by arranging for windows to be fitted from inside the building  ensuring that risks from working at height are reduced to a minimum. (c) Examples of information the client should provide include:  the location of buried services and underground tanks  details of hazardous and flammable substances stored on the site, and the presence of any remaining hazardous machinery or equipment  possible contamination of the ground or drains  the location of other hazards such as asbestos  details of weaknesses in the structure, such as fragile roofs or the presence of rot  ground conditions, such as possible instability and the existence of culverts  previous use of the land  means of access to the site and traffic routes  the proximity of neighbours  details of the project coordinator, if the project is notifiable  the Health and Safety file, if there is one in existence.

Question 14

Under the Work at Height Regulations, duty holders (employers, the self-employed, and any person that controls the work of others, such as facilities managers or building owners who may contract others to work at height), must ensure: 5

Answer 14

 all work at height is properly planned and organised  those involved in work at height are competent  the risks from work at height are assessed and appropriate work equipment is selected and used  the risks from fragile surfaces are properly controlled  equipment for work at height is properly inspected and maintained.

Question 15

Duty holders must also adhere to the following hierarchy for managing and selecting equipment for work at height:

Answer 15

 Avoid work at height where possible.  Use work equipment or other measures to prevent falls (where working at height cannot be avoided).  Use work equipment or other measures to minimise the distance and consequences of a fall, should one occur (where the risk of a fall cannot be eliminated).

Question 16

The first step in the risk management hierarchy in the Work at Height Regulations is to consider whether or not the need to work at height could be avoided. Examples of solutions, across a range of industrial sectors include: 6

Answer 16

 Building structures at ground level and lifting them into position on completion, (or in the case of road bridges tunnelling beneath them).  Tilt and turn windows, which can be cleaned from a safe position inside the building.  Use of water fed poles that allow windows to be cleaned from ground level.  Use of long handled tools that can be utilised from ground level, for example, long handled vacuum cleaners to clean dusty surfaces from ground level.  Vacuum filling raised hoppers from ground level.  Shrink-wrapping pallets at ground level can remove the need to sheet vehicles, which requires working at height.

Question 17

Principles of preventing falls and minimising the consequences of falls 3

Answer 17

 prevention takes priority over consequence minimisation (arrest)  collective measures take priority over personal protective measures  passive measures are preferred to active measures.

Question 18

Schedule 6 of the Work at Height Regulations states that a ladder should only be used for work at height if a risk assessment has demonstrated that the use of more suitable work equipment is not justified because of: 4

Answer 18

 The low risk - ‘light work’ (loads

Question 19

Hazards and Precautions When working on a ladder or stepladder care should be taken to avoid:

Answer 19

 Overloading - the maximum load stated on the ladder should not be exceeded.  Overreaching – the workers body should remain between the stiles, and both feet should be planted on the same rung throughout the task.

Question 20

Users should be trained and instructed to use the equipment safely, in accordance with the following rules: 7

Answer 20

(1) Ensure the ladder or stepladder is long enough (2) Ensure the ladder or stepladder rungs or steps are level for use(3) Ensure the weather is suitable(4) Wear robust, sensible footwear(5) Know how to prevent members of the public and unauthorised workers from using them(6) Know that certain medical conditions or medication, alcohol or drug abuse could stop them from using ladders(7) Know how to tie a ladder or stepladder properly

Question 21

Standard

Answer 21

Vertical (upright) tube.

Question 22

Ledger

Answer 22

Horizontal tube - in the direction of the larger dimension of the working scaffold.

Question 23

Transom

Answer 23

Horizontal tube - in the direction of the smaller dimensions of the working scaffold.

Question 24

Raker

Answer 24

Load-bearing tube inclined at 75o and coupled to the second lift. Used where normal ties are inappropriate.

Question 25

Façade (Face) bracing

Answer 25

Diagonal tube parallel to the façade of the building.

Question 26

Ledger bracing

Answer 26

Diagonal tube perpendicular to the face of the building.

Question 27

Base plate

Answer 27

Metal plate used to spread the load from a standard (base plates with vertical adjustment are called base jacks).

Question 28

Sole board

Answer 28

Timber plank positioned beneath two or more base plates to evenly distribute the scaffold load over the ground.

Question 29

Coupler

Answer 29

Device used to connect two tubes.

Question 30

Tie

Answer 30

Means of securing the scaffold to the building

Question 31

Bay

Answer 31

Distance between pairs of standards (parallel to face of building).

Question 32

The main hazards associated with scaffolds are:

Answer 32

 Collapse of the scaffold  People falling from the scaffold  Objects (including components) falling, or being dropped from the scaffold  People walking into the scaffold.

Question 33

Statutory inspection of scaffolds Scaffolding must be regularly inspected by a competent person:

Answer 33

(a) Immediately after it has been constructed (the scaffold contractor should provide a hand-over certificate within 24 hours of completing the scaffold). (b) Before anybody goes on to it (this may be some time after it has been built). (c) After any incident that may have damaged it. For example: after a storm or vehicle impact. (d) Every 7 days (a formal report must be completed and entered into the site register).

Question 34

An independent tied scaffold to a new ten-storey office block has collapsed into a busy street. (a) Outline the factors that may have affected the stability of the scaffold. 8 marks (b) Outline the main principles of scaffold design, erection and use to ensure the stability of such a scaffold. 12 marks

Answer 34

(a) Factors affecting the stability of the scaffold include:  the original erection of the scaffold not following the intended design or the design itself being inadequate  the unsatisfactory bearing capacity of the ground on which the scaffold was sited  the scaffold foundation being undermined either by surface water or by site works such as excavation  the use of incorrect or damaged fittings such as non-load bearing couplers or those affected by corrosion  standards which were out of plumb or bent  a lack of ties  unauthorised alteration of the scaffold  overloading either with materials or because waste chutes became blocked  impact by a load suspended from a crane or by a road vehicle  severe weather conditions including high winds or snow. (b) The main principle to be followed in achieving the stability of the type of scaffold described in the question is to ensure that it is designed to carry all loads, is suitable for its use in accordance with BS EN 12811-1 and is constructed of sound materials and fittings. In practical terms this would involve setting standards on base plates on suitable sole plates taking care to ensure joints are staggered; fitting longitudinal and diagonal bracing and ledger braces at every other pair of standards and fitting vertical and horizontal ties which should be replaced by temporary ties in the event that any have to be removed. If the scaffold is erected in a position where there is likely to be movement of vehicles, protection should be provided to prevent damage from any collision that might occur. The scaffold should be erected only by competent persons and after erection should be used only at the designed and correct level of duty and not overloaded. Inspection by a competent person is necessary at intervals not exceeding seven days and additionally after alterations, damage or after a period of inclement weather.

Question 35

A three-storey building is situated with one side fronting on to a pedestrian walkway. The building is to undergo extensive maintenance to the external fabric which includes a sloping roof. (a) Outline the health and safety issues of the work that will need to be considered before work starts. 11 marks (b) Outline the features of a scaffold designed to provide a safe place of work for working at height during the maintenance activity. 9 marks

Answer 35

(a) Note: The issues relate to the safe management of construction work in an area where the public has access and are concerned with public safety such as the provision of barriers and screening to ensure protection from plant and falling materials, working at height requiring precautions to be taken to prevent falls and to ensure safe access for materials, and the introduction of safe systems of work for operations such as sand blasting and water jetting. Therefore, an outline of issues to consider before work starts would include:  the requirements for suitable plant and equipment including roof ladders bearing in mind the requirements of the Working at Height Regulations  the provision of access for vehicles and the arrangements for the movement and storage of materials on site  the security of the site and the need to ensure the safety of the building’s occupants if they are to remain whilst the work is completed  the likely presence of any hazardous materials such as lead and/or asbestos and those likely to be flammable  the need to consult any existing health and safety files or structural surveys which have been completed  the proximity of any utility supplies and the effect that the proposed work may have on neighbouring buildings  possible health issues arising from exposure to the sun or inclement weather, or to dust from bird or animal droppings  the provision of personal protective equipment such as hard hats, eye protection and fall arrest equipment, such as harnesses and the provision of adequate welfare facilities. (b) An outline of features of a suitably designed scaffold would include:  The correct erection of the scaffold, for example, ensuring the use of upright standards positioned on base plates on stable level ground, horizontal ledgers and tight couplers with adequate bracing and guard rails, and the need to tie it into the structure.  Ensuring the working platforms were wide enough, fully boarded and provided with safe access minimising or plugging the gap between the scaffold and the wall of the building.  The provision of a special working platform below the eaves.  Protecting the scaffold at its base from impact by vehicles.  Using a chute for the disposal of waste materials.

Question 36

A company has been contacted to undertake maintenance work on the roof of a building that is partly constructed of fragile material. (a) Identify the characteristics of the fragile material that may contribute to the risk of falls through the roof. 6 marks (b) Outline the measures to be taken to minimise the risk to persons involved with the work. 14 marks

Answer 36

(a) Characteristics that may contribute include:  the type of material (for example fibre board, asbestos or polycarbonate) and its thickness  the age and condition of the material which might be corroded, rotten, water sodden or weathered  the sheet profile and the design of the supporting structure such as the purlins together with the span between the roof supports  the fact that the fragile material might well be camouflaged by deposits of dirt and other material. (b) An initial reference should have been made to the importance of completing a full risk assessment of the operation to be carried out, and the consequent production of a method statement detailing the safe system of work to be followed. This would describe the proposed means of access to the area of work, such as the provision of scaffolds and crawling boards, and the erection of edge protection comprising guard rails and toe boards to prevent the falls, both of persons and materials from the roof. It would also be necessary to identify areas of the roof containing fragile materials, to mark them with barriers or signs and to prevent falls through them by the use of covers. An additional safeguard would be to provide safety nets and/or air bags under the areas of the roof which contained fragile materials. For certain tasks, the use of safety harnesses with adequate fixing points might also be necessary. Arrangements, such as a hoist, might be needed to transport tools, equipment and materials to the roof, while the use of chutes should be considered for the removal of rubbish. An important factor in carrying out this type of work is to ensure the use of competent personnel fully briefed and aware of the risks involved and the precautions to be observed and to draw up procedures to deal with any emergency that might occur. Finally, measures would have to be taken, such as the erection of barriers and signs, to prevent occupants of the building from passing beneath areas of the roof where work was being carried out, and also members of the public from passing in close proximity to the building.

Question 37

Pre-demolition surveys A range of pre-demolition surveys may be necessary to pull together pre-construction information for the principal contractor, including: 3

Answer 37

 Structural surveys to determine structural hazards.  Hazardous substance surveys to determine site specific hazards. For example: the presence of asbestos, the storage of hazardous materials on site, and contaminated land.  Site / environmental surveys to determine all other site specific issues such as access, ground conditions, overhead obstructions, neighbours, etc.

Question 38

Pre-demolition processes Before demolition proper can begin the following will need to be addressed:

Answer 38

 Gas, electricity, water, telecommunications and other site services need to be isolated or disconnected before demolition work begins. If this is not possible, pipes and cables should be labelled clearly, to make sure they are not disturbed.  Hazardous substances, such as asbestos, will need to be removed in a controlled manner.  Soft-stripping (the removal of non-structural components) and hard-stripping activities (the salvaging of structural components such as architectural ironwork, dressed stone, hardwood timbers, etc.) should be completed before structural demolition begins.

Question 39

Demolition - principles and techniques Structural demolition may be undertaken in accordance with the following principles: 3

Answer 39

 Piecemeal (progressive) demolition  Controlled (deliberate) collapse  Pre weakening through deliberate removal of structural components.

Question 40

There are a number of demolition techniques available which may be used in combinations or at different parts of the demolition site. The techniques broadly fit into one of four categories:

Answer 40

(1) By hand, using powered tools and often involving working at height. (2) By machine, comprising: a base machine (compact machine, high reach machine, tower crane), equipment (boom and dipper arm, for example), and attachments (hydraulic such as pusher arms, impact hammers or shears and non-hydraulic, such as demolition balls, wire ropes, drills and saws). (3) By explosive. (4) By other means, including gas expansion bursters, hydraulic bursters, expanding chemicals, hot cutting and high pressure water jetting.

Question 41

Demolition machinery and attachments As shown in Figure 9.26, demolition machinery comprises:

Answer 41

 a base machine (compact machine, high reach machine or tower crane)  equipment (for example: boom and dipper arm)  attachments (hydraulic and non-hydraulic – as shown in Table 9.8).

Question 42

The hazards presented by demolition activities will vary depending upon the techniques used. The main safety hazards include: 7

Answer 42

 Premature or unexpected collapse  Falling materials  Falling from height  Impact from site vehicle movements  Mechanical hazards associated with moving parts of heavy plant and hand tools  Fire and explosion from site services, hot work, or use of explosives  Confined spaces – cellars and voids.

Question 43

The hazards presented by demolition activities will vary depending upon the techniques used. The main health hazards include: 11

Answer 43

Chemical  Lead dust and fumes from paint removal, hot cutting, etc.  Silica dust from stone crushing or shot blasting.  Asbestos fibres from insulation materials, etc.  Gases vapours and fumes from hot cutting, chemical residues, soil contamination, organic decomposition, bonfires, etc. Physical  Ionising radiations from smoke detectors or lightning conductors or from historical uses of premises.  Noise from plant, explosive shot firing, etc.  Vibration – WBVS from driving plant / HAVS from use of pneumatic drills and breakers. Biological  Leptospirosis from contaminated surface water.  Ornithosis / psittacosis from bird droppings.  Tetanus from contaminated soil.  Food poisoning organisms from sewage.

Question 44

Precautions Irrespective of the demolition technique(s) used on a particular project, safeguards are designed around the following key principles: 3

Answer 44

 Effective work planning through site surveys and effective risk assessment.  The establishment and maintenance of safe working spaces and exclusion zones.  The development of safe systems of work, detailing appropriate precautions for the method of demolition used.

Question 45

An exclusion zone is a designated three-dimensional space from which all persons, including the public, are excluded during demolition activities. It should be designed to be adequate for the particular demolition activities. The exclusion zone is made up of four areas:

Answer 45

(1) Building/structure footprint (plan area) (2) Designed drop area (3) Predicted debris area (4) Buffer zone.

Question 46

An effective method statement will typically address: 9

Answer 46

 The sequence and method(s) of demolition detailing means for access, provision of safe working platforms and machinery requirements.  Details of pre-weakening of structures prior to demolition by explosion or pulling down.  Arrangements for protection of personnel and others through the establishment of exclusion zones.  Details for the making safe of electricity, gas and water supplies and site drainage.  Specification of temporary services required during the operation.  Detail methods for dealing with hazardous materials retained on site in machinery, pipework or tanks.  Methods for identifying the presence of hazardous substances such as asbestos on site and the methods to be used during its removal and disposal.  Requirements for personal protective equipment.  Arrangements for controlling site transport.

Question 47

The main hazards associated with excavations are: 12

Answer 47

 Ground movement / collapse of excavation sides  Surcharging  Ground and surface water  Stability of adjacent structures and services  Underground services  Overhead lines  People falling into excavations  Plant falling into excavations  Materials falling into excavation  Toxic gas and oxygen deficiency  Biological and chemical health hazards  Noise and vibration.

Question 48

Ground movement / collapse of excavation sides controls

Answer 48

Ground conditions should be regularly inspected by a competent person. The excavation should be battered or stepped, or supported.

Question 49

Surcharging occurs when

Answer 49

a load applied to the ground by plant, stored materials, spoil or structures increases the horizontal load on the excavation sides, causing them to collapse.

Question 50

SurchargingControls

Answer 50

 Barriers and signs to keep vehicles away.  Use of stop blocks for tipping vehicles.  Materials stored away from excavation (min 1.5m or > depth of excavation).

Question 51

Ground and surface water Controls

Answer 51

Water is channelled into sumps and removed using hydraulic pumps.

Question 52

Stability of adjacent structures and services Controls

Answer 52

 Shoring of structures.  Supporting of services.

Question 53

Underground services Controls

Answer 53

 Checking of existing plans.  Use of cable avoidance tools (CAT).  Appropriate digging techniques (not directly over services, hand tools in immediate vicinity – see below).

Question 54

Overhead lines Controls

Answer 54

Control plant movement beneath and near to overhead power lines (see Element C8).

Question 55

People falling into excavations Controls

Answer 55

 Provision of a substantial barrier, including guard rail, intermediate rail and toe boards.  Provision of safe access.

Question 56

Plant falling into excavations Controls

Answer 56

 Barriers and signs to keep vehicles away.  Use of stop blocks for tipping vehicles.

Question 57

Materials falling into excavations Controls

Answer 57

Materials stored away from excavation (min 1.5m or > depth of excavation).

Question 58

Toxic gas and oxygen deficiency Hazards

Answer 58

 Combustion gases from petrol or diesel engine equipment can collect within trenches.  Ground such as chalk or limestone in contact with acidic groundwater can liberate carbon dioxide.  Glauconitic sand (such as Thanet sand) can oxidise, causing oxygen deficiency.  Gases such as methane or hydrogen sulphide can seep into excavations from contaminated ground or damaged services.

Question 59

Toxic gas and oxygen deficiency Controls

Answer 59

 Keep generators clear of excavations.  Ground condition surveys.  Oxygen and gas monitoring.  Respiratory protective equipment (RPE).  Emergency arrangements.

Question 60

Biological and chemical health hazards

Answer 60

 Leptospirosis (Weil’s disease) from working near contaminated water.  Sewage from damaged sewers or sewer connections poses a risk of gastroenteritis.  Tetanus from a dirty penetrating wound.  Contaminated ground could contain asbestos, coal-tar residues, lead alkyls or mercurial compounds.

Question 61

Biological and chemical health hazardsControls

Answer 61

 Check site history.  Soil sampling.  Suitable PPE – overalls, gloves, shoes.  Welfare facilities – washing.  First aid arrangements.

Question 62

Noise and vibrationControls

Answer 62

 Specify low noise / vibration equipment and maintaining it in good order.  Limit time spent using equipment.  Suitable PPE (see Element B6).

Question 63

Use of 360o excavators After ensuring that the right excavator has been selected for the job there are five main precautions to be implemented:

Answer 63

(1) Exclusion: Most excavator related deaths involve a person working in the vicinity of the excavator rather than the driver. Fencing, bunting or other suitable barriers should be used to create and maintain a pedestrian exclusion area. (2) Clearance: Plant with minimal tail swing should be used if slewing in a confined area. Clearance of over 0.5m needs to be maintained between any part of the machine, particularly the ballast weight, and the nearest obstruction. (3) Visibility: The driver should have a good all round view and the excavator should be equipped with adequate visibility aids to ensure drivers can see areas where people may be at risk from the operation of the machine. (4) Signaller: To direct excavator operation and any pedestrian movements from a safe position. (5) Bucket attachment: Quick hitches can be used to secure buckets to the excavator arm. Check that you are able to implement and manage any quick hitch used. A number of deaths have occurred in recent years when the bucket has fallen from the machine. (See notes on ‘quick hitches’ later)

Question 64

There are three categories of worker who must be trained and competent regarding the excavator hazards and precautions:

Answer 64

(1) Drivers: should be trained, competent and authorised to operate the specific excavator. Training certificates from recognised schemes help demonstrate competence and certificates should be checked for validity. (2) Signallers: should be trained, competent and authorised to direct excavator movements and, where possible, provided with a protected position from which they can work in safety. (3) Pedestrians: should be instructed in safe pedestrian routes on site and the procedure for making drivers aware of their presence.

Question 65

The need for excavation can be avoided at the design stage by using trenchless technology for pipe laying, or pipe repair and rehabilitation.

Answer 65

Horizontal directional drilling uses a curved trajectory to enable a pipeline to pass under an obstacle, such as river or road, without the need for excavations at either end, as with horizontal boring techniques Impact moling uses a pneumatic piercing tool to create a bore hole. The approach compacts and displaces soil rather than excavating and removing it, therefore minimising disruption and ground reinstatement. Pipe bursting techniques can be used to replace an existing, damaged pipeline with a new pipeline of the same (or slightly larger) diameter. The old pipeline can be burst in-situ, or removed piece by piece and broken up as it is pushed out of the tunnel.

Question 66

Part 4 of the Construction (Design and Management) Regulations 2007 require that certain places of construction work are to be inspected by a competent person. (a) Identify: (i) when statutory inspections of supports excavations must be carried out; 3 marks (ii) the information that should be recorded in a statutory excavation report. 5 marks (b) Outline the particular features of an excavation that could result in it being considered unsafe. 12 marks

Answer 66

(a) (i) Under the Regulations, an inspection of an excavation must be carried out at the start of every shift before work commences, after an event that may have affected the stability of the excavation and following an unintentional fall of material. (ii) Information that should be recorded in the inspection report includes:  the name and position of the person making the report  the name and address of the person on whose behalf the work was carried out  a description of the place of work inspected including the plant and equipment in use  the date and time of the inspection  the details of any matter identified that could lead to risk, the action to be taken to prevent the risk and the details of any further action necessary. (b) Reasons that could lead to an excavation being considered unsafe such as:  its proximity to adjoining structures  the inadequacy or incomplete nature of the means of support for the type of soil where the excavation was sited  damage to or the dislodgement of the supports provided such as metal sheets or walings  the presence of excess water either from damaged pipes or land drains  damaged services and the presence of fallen rock, earth or other materials in the excavation  a failure to provide adequate means of access and egress  the presence of spoil or materials placed too close to the edge of the excavation  a failure to provide stop blocks despite the use of vehicles in close proximity to the excavation  the presence of gas or fumes, or biological or chemical hazards  a failure to provide adequate barriers and warning signs to prevent persons from approaching and falling into the excavation.