Assessing Environmental Impacts – Noise Quality

So, your local newspaper just announced that a major developer wants to put in a new mixed-use project. They want to tear down existing buildings, create new roads, add public areas, and put in several new buildings with underground parking, retail at street level, and high density housing above.

Whether you are part of the design team or one of the neighbors, there are many aspects to assessing the environmental impact of future projects that must be considered. While many of us are familiar with the more common aspects of environmental impacts such as adverse impacts on local wildlife, not everyone realizes that the initial planning process should also assess the noise, air, and water quality as well as provide recommendations as to the best way to minimize the impact on the neighbors and the environment.

In a previous blog post, we provided a summary of the various terms used when discussing environmental noise. In this post, we provide a further discussion of noise quality. Future blog postings will discuss air and water quality.

Federal, state, and local government agencies have enacted laws, ordinances, and regulations to control environmental noise. The Environmental Impact Statement (EIS) then becomes an important document for environmental noise control in urban planning. The noise impact assessment portion of the EIS may take many forms, including potential damage to hearing, potential physiological responses, annoyance, and general community responses. Typical noise impact assessments in the EIS take the form of comparisons between existing and future noise levels with the noise criteria of federal, state and local governments.

The first step of noise impact assessment is to understand the existing noise environment. It can be achieved by taking noise measurements at the project site, obtaining current noise regulations through government agencies, and determining existing and future noise sensitive receptors (i.e. the neighbors). The purpose of the noise impact assessment is to reduce the noise impact to the required statutory requirements at the existing and future noise sensitive receptors. Therefore, determining the future noise sensitive receptors is a very important part of the assessment.

The second step is to understand the noise impact during the construction stage. This can be achieved by obtaining the anticipated construction activities, construction periods, and construction equipment to be used during a typical day. From this information, we can calculate the noise levels to the nearest sensitive receptors. If the construction noise levels exceed the statutory requirements, then appropriate noise mitigation measures should be recommended, such as selecting quiet equipment and working methods, avoiding simultaneous “noisy” activities, reducing the number of equipment operating in critical areas, installing temporary noise barriers, etc.

The third step is to understand the noise impact after the project is completed. This can be achieved by using noise-modeling methods to predict the noise levels (Leq and Ldn) at existing and future noise sensitive receptors. If the computed noise levels exceed the statutory requirements, different mitigation measures should be recommended, such as installing noise barriers, acoustic enclosures, etc.

The forth step is to evaluate the economic benefits of all the recommended noise mitigation measures, and choose the most cost-effective noise mitigation measures.

The final step is to submit the EIS to the appropriate government agency for approval so the project can move forward.

In another blog post we’ll discuss air quality issues.