Encyclopedia of Environmental Science and Engineering, Volume I and II

330 ENVIRONMENTAL ASSESSMENTS AND RELATED IMPACTS

the site. This often leads to time consuming and costly litiga-

tion between applicants and their design professionals.

The analysis of traffic-induced noise and air quality

impacts in environmental assessment reporting has been

conducted in most reports since the passage of NEPA.

Normally, many attendees at public hearings are confused

about the logarithmic nature of decibel levels (the stan-

dard noise descriptor) and how multiple sources of sound

are added in terms of decibels. In addition, they generally

do not have the technical background to assess results gen-

erated from noise and air pollution mathematical models

often employed by professionals preparing assessments.

However, the public, over the last thirty years, have dem-

onstrated an increasing tendency to voice more concerns at

hearings related to noise and air quality issues, and quality

of life issues as a whole.

In addition, because traffic noise generation by vehicles

on public highways, and rail and aviation noise generation

are not normally regulated by municipalities, and further,

because the agencies which regulate rail and aircraft noise

have less stringent or no standards of compliance at resi-

dential property lines (or properties in the case of aircraft)

compared to typical municipal noise ordinances, noise gen-

eration from these sources is being challenged more often

by the public.

In populated and well developed communities, the

remaining parcels to be developed are often situated in close

proximity to rail lines, airports and heavily traveled high-

ways. Lastly, society is trending toward greater longevity,

and noise and air pollution more adversely affect senior citi-

zens than the rest of the general population. As such, credible

assessment reporting in the disciplines of noise and air qual-

ity, as well as providing meaningful mitigation techniques in

site design and orientation for residential applications pro-

posed in proximity to major potential noise and air quality

generators are critical for one to be successful in convincing

an often cynical public.

Lastly, the air quality standards promulgated for mobile

source (i.e., traffic) pollutants in the Clean Air Act of 1970,

with the exception of ozone (which is generated about

equally by mobile and stationary air pollution sources) have

remained unchanged, yet most urban areas, where air pol-

lution generation is normally at the highest levels, have

remained in compliance over the period in question. This has

occurred despite a major increase in driver registration and

vehicular miles traveled on US highways since 1970, due in

major parts to technological advances (e.g., catalytic muf-

flers since the mid 70s, which have reduced vehicular emis-

sions to offset population growth. However, in the United

States in the near future, we will be challenged with the need

to find alternative fuel sources for vehicles which generate

less air pollutants if we are to remain in compliance with

the Ambient Air Quality Standards promulgated in 1970 for

mobile source pollutants.

In summary, issues such as wetlands delineation, air pol-

lution and traffic-induced noise must be given serious atten-

tion in assessment reporting for applications to be approved

by reviewing bodies. Increased public awareness on how

effectively to critique decision-making methodologies and

basic assumptions associated with mathematical models

employed in conjunction with assessment preparation is

placing an increased burden to defend properly their appli-

cation in the reporting process.

RISK ASSESSMENT REPORTING AND ASSOCIATED

STRATEGIES

If an application involves a project which can (or may) be

deemed as a potential threat to life, limb or property result-

ing from its construction and/or operation, reviewing agen-

cies will normally require a risk assessment to be prepared

in addition to an environmental assessment. The function of

a risk assessment is to quantify (where possible) the risk of

death, injury and potential loss of personal property asso-

ciated with the worst-case scenarios that can be perceived

occurring on the subject site. Typically, risk assessors are to

prepare their assessment utilizing the principle of Murphy’s

Law that “all that can go wrong, will!” All aspects of the

operation on the site, including transportation, handling,

storing, processing of the product involved and related

by-product generation and disposal must be considered, and

probabilities of risk quantified (based upon industry practice

and history) for each phase of the operation on an annual

basis.

For all aspects of risk considered, one assesses the

so-called “safe separation distance” (SSD) from the site

should a particular failure mode occur either on the site or

by transmission from the site (e.g., vapor dispersion of a

product or by-product). If potential sensitive receptors are

located within the SSD, then those cumulative risks from all

potential modes associated with the site in question must be

quantified. For parcels located beyond the SSD, the risks are

considered negligible.

Once a potential risk is quantified for a particular site,

mitigations to the risk can be investigated, based on the pro-

posed implementation of mitigating factors for the subject

site and the historical value based on industrial experience

related to their effectiveness in reducing risk. Examples of

mitigating factors may include the following: availability

of fire-fighting capability on the site or within a short dis-

tance of the site, accident history of the particular company

involved, training of personnel on site, etc. Generally, a

value between 0 and 1 is assessed for each mitigating factor,

which is then multiplied by the cumulative risk probability

for the proposal. This, in essence, produces a reduced prob-

ability of risk.

The risks associated with the proposal are typically

compared to the “normal risk” to which individuals are

subjected in conducting their daily lives. To develop such

a perspective, published annual fatality statistics due to

accidents (vehicular, aircraft, drowning, lightning, elec-

trocution, falls, etc.) are available from all industrialized

nations which, based on total population statistics, can be

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