Environmental Impact Assessment(EIA) Registration for the ...

REVISED PROJECT DESCRIPTION AND ENVIRONMENTAL IMPACT ASSESSMENT (EIA) REGISTRATION
FOR THE NEPISIGUIT FALLS GENERATING STATION MODIFICATION AND REHABILITATION PROJECT
1.2 PURPOSE/RATIONALE/NEED FOR THE PROJECT
A study commissioned in 1998 by Smurfit–Stone to characterize the integrity of the NFGS
recommended refurbishment and maintenance to bring the NFGS up to modern day standards
and address known deficiencies. The refurbishment of the NFGS is being undertaken in a
phased approach. The first phase was undertaken in 2000, and consisted of replacing the main
dam and sluiceway with a rubber dam and a new submerged gate.
The purpose of the Project is to undertake the second phase of the refurbishment and
maintenance, which has been planned for the NFGS since 1998. This phase includes the
refurbishment of the forebay spillway dam and the installation of a new 1.2 m (3.9 ft) diameter,
85.3 m (280 ft) long rubber dam and various associated and other refurbishment works.
Prior to NB Power’s purchase of the NFGS in 2007, the forebay spillway dam had an additional
1.2 m of hold back capacity from the use of wooden flashboards (Photo 1, Appendix B, which
shows the forebay dewatered for construction of phase I). These flashboards did not allow for
the required response to flood levels and ice jams in the winter months, and were therefore
removed for 5 to 6 months of the year. This practice reduced the water capacity of the forebay,
and thus lowered the service level and generating potential of the NFGS. The flashboards had
to be removed manually during flooding and ice jams, which presented health and safety
concerns. NB Power permanently removed the flashboards due to safety concerns.
Undertaking modification and rehabilitation activities on the forebay spillway dam structure,
which is in poor repair (Photo 2, Appendix B), will increase its lifespan. Replacing the
flashboard system with a rubber dam will reinstate the full operating potential of the NFGS by
holding back water and restoring the generating capacity of the station to what it was prior to
removal of the flashboards. This will increase efficiency in operation, and improve flood control.
The Project includes the replacement of the existing coarse trash rack system, which was
damaged in December 2010 by high water levels and ice (further discussed in Section 2.2.7),
although the primary cause was the cumulative effect of deterioration and corrosion, resulting in
failure of the coarse trash rack system. The coarse trash racks protect the power house
components by entraining debris that would otherwise run through the systems and cause
damage to various mechanical components. The coarse trash racks also provide structural
support to the intake deck on the forebay side of the power house.
The NFGS is an important part of NB Power’s generation portfolio, as it represents dependable,
renewable energy on a continuous basis that offsets the use of fossil fuels.
Page 2 June 15, 2011