Environmental Engineering Reference
In-Depth Information
potentially affecting the species or their habitat had occurred since publica-
tion of the first document.
Similarly, for comparable proposed actions that have been the subject of
environmental impact evaluation, the non-site-specific impacts can often be
referenced and not repeated. The U.S. Air Force (USAF) Over-the-Horizon
(OTH) NEPA program represents an example of this approach. This program
was a continent-wide radar detection effort addressing security threats from
airplanes, ships, and missiles at a range of up to 5000 km from the continental
borders of the United States. In order to transmit the radar beam over such
a range and have the returning signal be strong enough to detect, tremen-
dous transmission energy was required. The exposure of humans and wild-
life to such high levels of energy was a significant environmental and public
health concern to the USAF. To address this concern they conducted extensive
research into the environmental impacts and health effects of the radar beam
as a part of the Maine OTH system, which was the first of four planned sys-
tems (the others were in Minnesota/North Dakota, California/Oregon, and
Alaska). The research and EIS for the Maine system established the allow-
able threshold exposure levels for the non-ionizing electromagnetic radiation
from the radar beam and developed mitigating measures to address impacts
on public health and wildlife from the radar's non-ionizing radiation. The
mitigation measures included fencing to exclude wildlife within the zone of
highest radiation and land use controls at greater distances within the radar
beam to avoid public health impacts. The research, impact prediction, and
mitigation measures developed for the radar in Maine were only summarized
and referenced in the EISs for the other systems. This allowed the other EISs
to focus on more site-specific impacts such as cultural resources and wild-
life migration as discussed elsewhere in the topic (Section 5.2.5). Addressing
common impacts in the first EIS permitted streamlining the entire NEPA
process for subsequent environmental impact analyses, allowing them to be
completed in approximately one year for each system as opposed to the more
common two- to three-year duration of the typical EIS.
6.2.2
Supplemental Environmental Impact Analysis Documents
Supplemental EISs, EAs, and other environmental impact analysis docu-
ments are a convenient and efficient way to address something that was
neglected in the original document, changed conditions, or new informa-
tion. It is an efficient approach because the entire process does not need to
be reinitiated, and the supplemental document can focus on one or very few
issues that necessitated the supplementation. The most common applications
of supplemental documents are:
r There is a relatively minor change in the details of the proposed
action.
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