Excavations & Confined Spaces

Under WAHR 2005, what is an 'excavation'?

• AOnly trenches dug for drainage or service runs that are deeper than the height of the person working inside them at the time
• BA hole or depression in the ground made by removing material, including trenches, pits, shafts, and underground chambers✓
• COnly permanent structures
• DOnly large holes

Answer: Excavations include trenches, pits, shafts, chambers, and other holes made by removing material. The safe management of excavations is critical to prevent collapse.

What are the main hazards associated with excavations?

• ACollapse of sides, falls of persons/objects, water ingress, and atmospheric hazards✓
• BOnly noise
• CDust and noise from the excavator, which are the only hazards once the sides have been battered back
• DExcavations are inherently safe

Answer: Excavation hazards include: collapse of excavation sides, falls of people or objects into excavations, water ingress, gases (atmospheric hazards), and struck-by hazards.

What is 'trench support' and when is it required?

• AWaived for shallow trenches
• BTemporary structures (shoring, sheet piling, supports) preventing collapse; required based on soil type and depth✓
• COnly for trenches deeper than three metres, since shallower ground will stand unsupported for the length of a shift
• DOnly if workers complain

Answer: Trench support is required to prevent collapse of trench sides. The type and depth of support depends on soil type, depth, and weather. Competent persons must design support.

What is 'benching' in excavation work?

• AA rest area cut into the side of an excavation where operatives can shelter from the weather during their rest breaks
• BA method of compacting the base of an excavation before concrete is poured, unrelated to the stability of the sides
• COnly used in mines
• DA stepped or sloped formation of excavation sides to prevent collapse (used as alternative to full support)✓

Answer: Benching involves creating steps or slopes in excavation sides instead of vertical walls. This reduces collapse risk and can be an alternative to support systems if designed correctly.

What must be done regarding 'water management' in excavations?

• APlacing sandbags around the top of the excavation, which is enough to keep surface water out of the trench during rain
• BAssess water risk, implement controls (pumping, dewatering, drains), prevent flooding of adjacent properties✓
• CPumping water out only once it reaches waist height on the operative, discharging it to the nearest surface drain
• DIgnore water ingress

Answer: Water management in excavations includes: risk assessment, pumping systems, dewatering arrangements, checking for water damage to adjacent structures, and preventing flooding.

What is a 'confined space' under health and safety law?

• AA space with limited entry/exit, not designed for continuous occupancy, and potential for hazardous atmosphere✓
• BOnly sealed rooms
• COnly underground spaces
• DAny enclosed area

Answer: A confined space has: limited means of entry/exit, inadequate ventilation, risk of hazardous atmosphere (oxygen deficiency, toxic gas, flammable atmosphere), or other risks.

What are the main hazards in confined spaces?

• AOnly darkness
• BHazardous atmospheres (gases, oxygen deficiency), flooding, physical hazards, isolation, loss of consciousness✓
• COnly temperature
• DOnly noise

Answer: Confined space hazards include: hazardous atmospheres (toxic gases, oxygen deficiency, flammable gases), flooding, drowning, engulfment, heat stress, physical hazards, and isolation.

What is a 'confined space permit' and what should it contain?

• ASet aside where entrants have been trained in confined space working and hold a current certificate for the type of space involved
• BA single document issued once for the whole project, listing the confined spaces on site and the operatives who are trained to enter them
• CFormal authorization system specifying hazards, controls, gas test results, rescue procedures, and competent persons involved✓
• DA permit needed only where a space has previously been found to contain gas, as recorded in the site's confined space register

Answer: A confined space permit formalizes authorization for entry, specifying: identified hazards, test results (atmospheric monitoring), control measures, rescue arrangements, and authorized personnel.

What is 'atmospheric monitoring' in confined spaces?

• ATesting the air before and during entry for oxygen level, toxic gases, and flammable atmosphere✓
• BUnnecessary provided that the space is left open and ventilated for an hour before anyone enters it
• COnly visual inspection
• DTesting required only in spaces below ground level, since spaces at or above ground level ventilate naturally

Answer: Atmospheric monitoring in confined spaces requires testing for: oxygen content (typically 19.5-23.5%), toxic gases (H₂S, CO), and flammable atmosphere. Continuous monitoring is often needed.

What is the 'entry supervisor' role in confined space work?

• AA competent person managing the confined space entry, coordinating rescue, monitoring conditions, and ensuring procedures are followed✓
• BA nominal role
• COnly required for excavation
• DOnly the entry person's role

Answer: An entry supervisor remains outside the confined space, monitors conditions, maintains communication with entrants, manages rescue readiness, and can order evacuation if needed.

What is a 'rescue team' and what must they be trained in?

• APointless, because the site's emergency plan already names the fire and rescue service as the responders for any confined space incident on the project
• BCompetent personnel trained in rescue techniques, equipment use, first aid, and emergency procedures for safely extracting people from confined spaces✓
• CThe site's appointed first aiders, who may enter the space to retrieve a casualty as soon as the alarm is raised, provided that they are wearing a dust mask
• DOnly security guards

Answer: A rescue team must be trained and equipped to safely rescue a person from the confined space using proper equipment and techniques without risking the rescuers.

What is 'engulfment' in confined spaces?

• ABeing surrounded or buried by material (e.g., grain, sand, liquid) causing asphyxiation or injury✓
• BFlooding of a space by rainwater entering through the access hatch during a period of heavy weather
• CBeing locked inside a space when the access hatch is closed by another worker who is unaware of the entry
• DLoss of lighting inside the space, leaving the entrant unable to see the route back to the access point

Answer: Engulfment occurs when a person is surrounded or buried by material (solids or liquids) in a confined space, often causing rapid asphyxiation. Examples include grain silos and tanks.

What emergency response measures are needed for confined spaces?

• AA telephone kept in the site office so that the emergency services can be called if the entrant fails to reappear within the expected time
• BA mobile phone is sufficient; entrants are expected to make their own way out and call for help if the conditions change inside
• COnly a first aid kit
• DEmergency procedures, rescue equipment, communication systems, trained rescue team, and prompt access to emergency services✓

Answer: Confined space work requires: emergency response plan, rescue equipment, communication systems (radio, rope systems), trained rescue team on standby, and access to emergency services.

What is 'ventilation' in confined space management?

• ARedundant
• BOnly opening doors
• COnly natural air flow
• DSupplying fresh air to remove hazardous atmospheres or maintain safe conditions during work✓

Answer: Ventilation involves supplying fresh air via fans or blowers to displace hazardous gases and maintain safe atmospheric conditions. Both natural and mechanical ventilation may be used.

What is a 'competent person' for excavation and confined space work?

• AOnly a chartered civil engineer, who must personally supervise every entry and every excavation carried out on the site each day
• BAnyone with a hammer
• CPerson with knowledge, experience, and training to manage excavations/confined spaces, assess safety, and supervise work✓
• DOnly inspectors

Answer: Competent persons for excavations and confined spaces need: understanding of soil types and support systems, ability to assess hazards, knowledge of regulations, and practical experience.

What must be done to control 'dust' in excavation work?

• AMeasures needed only in windy conditions, when dust is carried beyond the boundary hoarding into neighbouring property
• BIssuing disposable masks to the gang, which removes the need to control the dust at the point where it is created
• CIgnored in the open air, because dust generated outdoors disperses before it can reach a harmful concentration
• DUse water spraying, local extraction, respiratory protection, and work planning to minimize dust inhalation✓

Answer: Dust control measures include: water spraying, extraction systems, personal respiratory protection (as last resort), and work methods that minimize dust generation.

What is a 'competent support system' for an excavation?

• AOnly concrete blocks
• BAny propping arrangement the gang considers adequate, provided the operatives have several years of experience in excavation work
• CEngineering-designed support system (shoring, sheet piling, or braces) appropriate for soil conditions, depth, and workload✓
• DAny wooden props

Answer: Competent support systems are engineered specifically for the excavation considering: soil type and stability, depth, water table, ambient temperature, and work activities.

What must be done regarding 'utility strike prevention' in excavations?

• AOf little concern
• BIdentify underground utilities, mark locations, use safe digging practices, contact utility companies before excavation✓
• COnly call before digging
• DOnly relevant for large projects

Answer: Utility strike prevention requires: locating utilities (electrical, gas, water, telecommunications), marking their position, using safe digging techniques, and contacting utility companies.

What is 'sloping' versus 'shoring' in excavation design?

• AOnly shoring is acceptable, because sloping the sides of an excavation is prohibited in the UK where it uses more ground than necessary
• BThe same thing
• CSloping angles the sides; shoring supports vertical sides using engineered systems. Choice depends on soil type and space available✓
• DOnly sloping is safe

Answer: Sloping reduces the excavation angle to prevent collapse (typically 45-60 degrees depending on soil). Shoring uses support systems for vertical or near-vertical sides when sloping is not feasible.

What is a 'rescue plan' for confined space entry?

• AA plan required only for spaces deeper than three metres, on the basis that any shallower space can be reached by hand from the surface above ground
• BA short written note kept with the permit which states that the emergency services will be called if any of the entrants gets into difficulty inside the space
• CAn optional document, produced only where none of the entrants named on the permit has previously worked in a confined space of that type on this site
• DA detailed plan specifying rescue equipment, trained rescue team, communication methods, and procedure for safely removing a person in distress✓

Answer: A rescue plan must specify: available rescue equipment, trained rescue team contact/location, communication systems, extraction procedures, medical support, and testing protocols.