Multilevel Environmental Impact Analysis - Environmental Impact Analysis: Process and Methods - page 243

that the planning and environmental analysis process for the other aspects of
the cleanup would take a long time and that inadequately treated wastewater
and sewage sludge would be discharged to Boston Harbor every day while
the evaluation of alternatives was completed. They also learned from the eval-
uations, as part of the initial EIS conducted for the site selection, that much
needed to be accomplished to ready the site for the new 3.8 million cubic meters
(1 billion gallons) a day wastewater treatment plant because the site had:
a prison; Fort Drummond, a World War II coastal fortification; an existing
wastewater treatment facility that had to maintain operation during con-
struction; and a drumlin (geologic formation). All of these had to be removed
in order to construct the new wastewater treatment facility that would be
in full compliance with the Clean Water Act. In addition, the site selection
process identified the traffic impacts to the adjacent town associated with
transporting workers and materials as unacceptable and committed to miti-
gation by constructing a marine terminal on Deer Island to reduce truck
traffic through the adjacent town. Thus, a decision was made to conclude
the initial EIS, tier the remaining decisions, and implement aspects of the
proposed action that had been fully evaluated in compliance with NEPA.
The site selection evaluation had fully considered impacts that would
be associated with construction on Deer Island, as this was a major issue
identified during scoping. Thus, initial site preparation could begin with-
out additional NEPA evaluation. The initial work consisted of demolition of
the prison, fort, drumlin, and portions of the existing wastewater treatment
works on the site and construction of the marine terminal. However, con-
struction of the new treatment facilities could not commence until there was
additional NEPA review of other aspects of the comprehensive plan such as
the level of treatment and discharge location.
The level of wastewater treatment, discharge location, and several other
aspects of the cleanup required some level of NEPA review as summarized
below (U.S. EPA 1988a and U.S. EPA 1988b). The decision was made to conduct
follow-up supplemental EISs or EAs, but based on current practice, terminol-
ogy, and interpretation, these follow-up documents would now be considered
tiered EISs. They did add additional information, so they had some charac-
teristics of a supplemental EIS; however, each one was a cascading purpose
and need based on the ROD from the initial EIS. The environmental impact
analyses tiered from the initial Boston Harbor Cleanup EIS were:
r Interim residuals management: Sufficient evaluation was conducted
during the initial EIS to identify an interim solution to the discharge
of sludge to the harbor and there was strong pressure to implement
the interim plan to stop daily discharge to Boston Harbor. Detailed
implementation of the interim plan was included in the ROD for the
initial EIS with the caveat that if a detailed design indicated environ-
mental implications not anticipated in the initial EIS, an EA or other
environmental analysis document might be required.