Cutting-edge methodologies and strict industry standards are being applied to all stages of drilling operations, but it remains a noisy business. Ambient noise generated on-site includes that from drilling rigs, air compressors, generators, vehicles, radios and warning signals. Whether work is being undertaken in relation to mineral resources exploration, piling, construction, quarrying, environmental testing, water well, ground consolidation or geothermal activity, steps must be taken to minimise noise.

High levels of noise are a problem in any industrial situation as they can inhibit worker communication; reducing productivity and increasing the chance of an accident.

Prolonged exposure to excessive noise can result in permanent hearing loss. Also, there is a myriad of other health problems linked to noise, including sleep disturbance, cardiovascular disease and psychological issues.

Along with the human costs, businesses need to be aware of the likelihood of litigation from workers whose health is affected if the correct steps have not been taken to protect them. In addition to the court costs and potential payouts, there is the management time involved when dealing with issues such as absences and staff cover.

In relation to projects in close proximity to housing, the safety of people within the surrounding neighbourhoods must also be considered.

Laws and regulations

Across the developed world, it is now accepted that exposure to noise should be kept below a level equivalent to 85 decibels (dB) to minimise occupational noise-induced hearing loss. That is less than the volume of a hand drill, which in comparison to the majority of commercial drilling equipment is not a lot. It is worth noting that on average people's pain threshold is around the 110dB level (16 times as loud as 70dB) so long-term damage can occur long before pain is felt.

As well as health and safety regulations, many countries have specific noise rules, such as the USA's Noise Control Act, Canada's Occupational Exposure Limits and the EU's Environmental Noise Directive (Directive 2002/49/EC). Employers should make sure they are aware of the relevant rules affecting their employees. The general principles include:

• taking action to reduce noise exposure
• providing employees with personal hearing protection
• making sure the legal limits on noise exposure are not exceeded
• maintaining and ensuring equipment provided to control noise risks is used
• providing employees with information, instruction and training
• carrying out health checks (for example monitor workers' hearing ability)

The risk of hearing loss increases with the magnitude and exposure time and the frequency of the noise; with higher frequencies doing more damage.

Identifying emissions

Technology can play its part in reducing noise within drilling operations. While noise cannot be eliminated, if it is accurately identified and mapped, it can be mitigated and workers' exposure reduced.

Noise emissions in drilling procedures come from a wide variety of sources. These sources vary widely in sound power, emitted frequency spectra, directivity and also in their timings. This makes evaluation and mitigation difficult.

The main problem in noisy locations is finding and documenting where the noise reaches 85dB, (the noise contour line). Workers must wear hearing protection in areas where noise levels exceed this. Hearing protection should also enable effective communication. Prominent signage should delineate areas where hearing protection is required. Failure to clearly define and mark the 85dB line can leave companies liable to fines. It is the role of the supervisor to ensure protection is always worn inside the line. It does not matter whether the high noise levels are inside or outside a building, the 85dB contour line is enforced.

Senior drillers and supervisors must ensure that personnel are competent for the assigned job, understand the hazards and job requirements and follow established health and safety procedures.

It is wise to develop a noise control plan, including procedures for noise surveys to define all areas where hearing protection is required. Set noise emission goals for the design of a new plant and equipment to maintain the lowest possible levels of noise exposure.

Workers can be supplied with noise dosimeters that keep track of their daily dosage of noise. Although there is an initial monetary outlay with this approach, it is better than paying for lawsuits from workers with hearing problems and paying for disability because of tinnitus and hearing loss. There can also be a benefit to being seen as an employer which cares about its workers - this helps recruitment, retention, morale and ultimately productivity.

Mapping levels

For many years, noise control engineers had to measure noise levels and then use their best judgment to control it. Today's technology means more realistic simulations are possible with distinct advantages over using measurements alone. A measurement yields only one noise level and it is impossible to find how much noise came from which source. Simulations using sound-mapping software can identify each level and source.

By using noise simulation software, it is possible to create a noise map of a drilling project and to show exactly what noise is coming from where. More importantly, it can show how mitigation measures can affect the flow of noise and protect workers. Noise mapping is mostly an exercise of tapping into existing data sources and compiling a simulation model from the data representing the drilling situation involved.

SoundPLAN's software is designed to be user-friendly. Noise can be displayed in coloured maps making it easy to understand the sources and propagation. They can also be produced in 3D and animated form so that the problem is truly understood. The most-advanced software is sophisticated enough to map a single project or an entire country depending on the situation.

Each noise map is unique according to project size, the geography, the objective, but most of all, on what data is available and can be readily acquired to be imported and used for the noise map.

Simulations allow the prediction of future levels of noise, whereas measurements cannot occur until the entity making the noise is physically there. When noise levels can be simulated, it opens up the possibility of introducing theoretical noise reduction measures and evaluating possible improvements. So, simulations allow you to work with ‘what-if scenarios' prior to setting up a new drilling operation. This could mean positioning equipment differently or setting up equipment in a different place, for example.

Once you have created a noise map for a drilling operation, you can introduce controls to start protecting workers against the problem noise. Using the maps, mitigation measures such as modifying or replacing equipment with quieter models can be taken. Noise suppression devices and techniques such as enclosures, screens and silencers can also be used. It takes a reduction of just a few decibels to significantly lessen the risk of hearing loss and the many other health issues excessive noise causes. Plant and equipment should also be checked regularly and maintained in good condition.