hile cement plants and their related quarries are typically located in rural areas, there are almost always noise-sensitive homes nearby. More recently, the encroachment of expanding communities has become an increasing challenge for existing plants and quarries. Accordingly, the cement industry faces a common challenge of greater environmental scrutiny from all levels of government and the communities with which they co-exist. In this regard, environmental noise is an important consideration, and can have wide-reaching impacts and serious implications for industrial facilities such as cement plants.
What is environmental noise, and why do I need to worry about it?
The simplest definition of noise is “unwanted sound”. In the context of environmental noise from industrial facilities, unwanted sound can adversely affect community members in a number of ways. It can interfere with people’s ability to enjoy their property. Unwanted sound can also interfere with restful sleep. If sufficiently disturbing, environmental noise can lead to complaints, either to the emitter of the noise, or to one or more levels of governing authority. It is this community response to noise that led to the development and enforcement of regulations/ordinances, etc., at various levels of government in most jurisdictions. It is important for operators of industrial facilities, particularly those that are as substantial as cement plants, to be aware of and ensure these legal obligations are being respected.
In some cases, there are federal regulations (or guidelines) on environmental noise; more common, however, are state/provincial or county/municipal level regulations, which apply under varying circumstances, and are enforced to varying degrees. For instance, in some jurisdictions such as Ontario, Canada, the provincial government must grant an environmental approval before a new plant can be constructed; applying for such approval includes demonstrating, through technical study, that the sound levels of the plant will comply with Provincial guidelines. Similarly, many jurisdictions require Environmental Assessments (also referred to as Environmental Impact Assessments, Environmental Impact Statements, among other terms) be completed prior to the granting of government approvals of major projects. In other cases, adherence to environmental noise standards can be a condition of funding from organizations such as the World Bank.
Beyond legal or funding obligations with regard to environmental noise, many leading industries maintain policies on corporate social responsibility, which promote accountability in several key areas, typically including environmental protection and the wellbeing of the community in which they operate or serve. Adherence to such policies can be the impetus for the proactive reduction of environmental noise emissions, rather than reactively addressing noise complaints as they occur.
What sorts of noise limits might apply to my plant?
The environmental noise limits that might apply to a cement plant vary widely from one jurisdiction to the next. In many cases, interpreting noise regulations/ordinances as well as determining whether the sound levels of a plant comply with any applicable limits warrants the assistance of an acoustical consultant. Nevertheless, the following are several aspects of noise regulations/ordinances that provide some insight into the sorts of limits that might apply to your plant:
- Where the evaluation is conducted
The noise limit can apply at any of several possible locations. Limits can be a “point of emission” criterion, governing the noise output of a source, regardless of where a listener may be. They can also apply at the property line of the industrial facility. In most cases, though, the limits are “point of reception” criteria, which apply at a neighbouring noise-sensitive property, such as a residence, hospital, school, or place of worship.
- Qualitative versus quantitative criteria for evaluation
Limits for environmental noise can be qualitative, quantitative, or sometimes both. A qualitative limit is based on a judgement or decision by an enforcement official (e.g. a noise control officer) usually regarding whether the sound is loud enough to be “likely to disturb”, without reference to any numeric sound levels. For instance, a “plainly audible” noise could be a violation of a subjective limit that prohibits such a condition. A quantitative approach assesses a measured sound level against a maximum permitted level stipulated in a regulation or ordinance. Quantitative limits have the advantage of removing bias (from an enforcement official), but are not without their complications, as discussed further below.
- Fixed versus relative limits
When it comes to objective criteria, they can be implemented in two ways (and sometimes both). One is a fixed limit that may not be exceeded (e.g. 50 dBA at a given location). The other is a relative limit that takes into consideration the presence of background sound from other sources (such as road traffic and/or natural sounds). Typically, the limit stipulates a maximum allowable increase over the existing background sound. A combination of the two involves a relative limit that is applicable in cases where appreciable and steady background sound is present, and a fixed “exclusionary limit” in cases where the background sound is low (the World Bank limits are of this form).
- Limits by type of activity, date or time
In some cases, certain activities are prohibited, either altogether, or by date and/or time. For example, prohibition of loading and unloading of materials during nighttime hours, and on Sundays.
While environmental noise limits, particularly quantitative ones, are generally based on sociological research studies of community response to noise, the differences in limits among different jurisdictions arise from the fact that interpretation of the research and experience-based judgement are needed in choosing a limit that best reflects the probability of noise impact or adverse community response. With that said, it is worth noting that complying with an applicable noise regulation/ordinance does not preclude the possibility of noise complaints, which may warrant the adoption of more stringent sound level targets, for risk-management reasons, as discussed in the following section.
I am designing a new plant (or expanding an existing one). What should I do?
Noise from a completely new plant could obviously result in a significant “wake up call” to the surrounding community, particularly a new cement plant in a relatively quiet rural area. For the expansion of an existing plant, such modifications can increase the overall sound levels in the community (or change the character of the sound that neighbours hear), which can also be of concern. In either case, the first step in addressing any potential concerns with regard to environmental noise is to identify and understand any legal obligations, as discussed in the previous section.
If there are no noise regulations/ordinances applicable in your jurisdiction, it may still be prudent to consider those of a nearby or similar locale. In the case of expanding an existing plant, it may be sensible to design the expansion such that plant-total sound levels do not increase in the surrounding community. The absence of a noise regulation/ordinance does not absolve an operator of its corporate/social responsibility to protect the wellbeing of their community.
Once targets for community noise levels have been identified and/or selected, the sound levels of a proposed new or expanded plant can be predicted using a computational acoustical model. Such 3-dimensional models can be populated with local topography, onsite and offsite structures (which afford acoustical shielding and reflections), and information regarding significant noise sources based on manufacturer’s data (where available), predictions using generic data from reference texts, or on measurements of similar equipment.
Note that, for important efforts such as this, leading suppliers of mechanical equipment to cement plants can expect acoustical data to be more frequently requested; to that end, having accurate acoustical data available can represent a competitive advantage. With a complete acoustical model of the site and surrounding area, the predicted sound levels of a proposed new or expanded plant can then be evaluated with respect to target levels; if noise control measures are found to be warranted, they can be efficiently designed to suit.
Case Study: Lafarge cement plant in Bath, Ontario
Click here to read the the brief case study on a comprehensive noise assessment, including the successful implementation of noise control, at the Lafarge cement plant in Bath, Ontario, Canada.
Cement Plants, Quarries & Environmental Noise Issues: Part 2
Part 2 of this blog article, discusses how to address noise complaints, the challenges and pitfalls of assessing noise emissions from a cement plant, the “big players” in terms of noise emissions at a cement plant, and typical noise control measures employed to address them.