5 Safety on investigation sites
COMMENTARY ON CLAUSE 5
A summary of relevant health and safety regulations is given in Annex A.
After this introductory clause, safety is only mentioned where a special reminder has been considered necessary, e.g. work in contaminated ground. However, it is emphasized that safety is of paramount importance for all persons involved in any and every activity in ground investigation and this includes the protection of the general public and the environment.
This British Standard describes procedures for ground investigations which inevitably involve some risk to site personnel, the public and the environment. Risk assessments should be carried out and an appropriate construction phase plan should be prepared beforehand and implemented at all stages of the work.
A construction phase plan should be prepared before any physical work is carried out, including field reconnaissance; robust safety starts with the identification of risks and appropriate mitigation measures. This plan should be maintained throughout the investigation and reviewed as and when any unexpected conditions are encountered.
The following procedures should be carried out:
- a) any potential hazards that might exist when carrying out ground investigations should be identified;
- b) a framework for safe working should be established following the principles of hazard removal, replacement or reduction in that order (this framework should be communicated to all workers before the start of works, and refreshed as appropriate through regular toolbox talks);
- c) working procedures to minimize risks from contaminants and physical hazards associated with the collection, transport, testing and disposal of samples and the use of machinery should be adopted;
- d) personal protection equipment and cleaning facilities to minimize any risks should be available; and
- e) procedures for response in the case of an accident should be available.
Safety documentation and procedures should take into account that even risks which people are familiar with on an everyday basis can increase in a working environment that is unfamiliar.
Where the use of hand tools could cause vibration-induced occupational health issues, e.g. in sampling or installation of instrumentation, appropriate control of risks should be implemented.
These steps cannot remove all risk from the site works and, therefore, the need for all personnel to exercise all due care and caution at all times should be emphasized.
NOTE This British Standard does not seek to address everyday hazards that might arise from the use of such items as sharp instruments, digging equipment, or the hazards of driving to and from a site. It is assumed that such hazards are satisfactorily dealt with by the personnel carrying out the investigation.
Investigation sites should be kept secure at all times so that members of the public cannot be injured; this includes ensuring that areas of the works such as excavations, boreholes and spoil materials are fenced off until restoration is complete. Instrument head works or reading cabinets should be secure, fenced off and highlighted.
5.2 Contaminated land and gas
Guidance on site safety issues to be addressed in any investigation involving contaminated land or gas affected sites should be obtained from BS 10175 (in particular Annex C of that standard), BS ISO 10381-3 and industry guidance.
Training should be given to ensure that personnel understand the necessary safety precautions.
Personnel should be provided with suitable protective equipment, taking into account the potential toxicity and other hazards anticipated (assumed or measured).
NOTE 2 Carbon dioxide and some organic pollutants in the gas phase in soil and sub-soil can present toxicological risks of varying severity. Methane, hydrogen sulfide and some volatile organic compounds (VOCs) can form explosive mixtures with air.4) Large concentrations of carbon dioxide (in addition to being toxic) and methane can cause asphyxiation due to the associated reduction in oxygen concentrations. Oxygen concentrations in the ground can also be dangerously low in the absence of elevated carbon dioxide or methane concentrations.
NOTE 3 Injudicious choice of drilling method can cause risks to drillers due to gas coming out of boreholes. It could also cause risks to the public (e.g. the occupants and users of neighbouring buildings due to displacement of gas from the location where drilling is taking place and the creation of explosive atmospheres in the local drilling area).
NOTE 4 A number of serious incidents have occurred as a result of surface emissions of toxic gases into occupied properties during the investigation and treatment of nearby former coal mine workings. Of particular concern are incidents where carbon monoxide has been measured or inferred as entering occupied properties from the mine workings below. Mine workings can also contain methane, hydrogen sulfide, carbon dioxide and oxygen-deficient-air, all of which can be hazardous to health if emitted at the surface. Coal Authority et al., 2012  gives guidance on the general procedures to be adopted when drilling or piling into former coal mine workings (including mine entries) and unworked coal. Prior to carrying out works that have the potential to intersect or disturb Coal Authority property, the Coal Authority request that their permission for the proposed works is obtained in accordance with their permitting procedure.5)
The location and route of all current and historical underground utilities should be ascertained in accordance with PAS 128; a similar search should also be made for above ground services.