Halifax Harbour Cleanup Inc. - Halifax Regional Municipality

6 Project And Review Perspective
2.2.3 Sewage Treatment Plant and
Oil-from-Sludge Facility
The STP/OFS facility will be located on a Qd-hectare artificial
island, “Ives Island,” to be constructed at Ives Cove, 30 metres
off the north end of McNabs Island. About 1.1 million
cubic metres of fill will be used to create the island, which will
be drumlin-shaped to simulate the contours of surrounding
landforms. The STP/OFS facility will be completely enclosed.
The artificial island will be large enough to accommodate ultimate
design capacity for primary treatment. Upgrading to secondary
treatment will require island expansion.
Sewage will be brought to the site by an under-Harbour tunnel
and lifted 60 metres into the plant by the main pumping station.
The sewage will undergo preliminary treatment at the
headworks, which consists of screening, and removal of grit,
scum and grease. After processing, solid wastes (screenings
and grit) will be disposed of, and the grease and scum will be
pumped to the OFS facility. The sewage itself will flow to the
primary clarifiers.
Primary clarifiers will remove about 50% of the suspended
solids at peak flow and about 65% at average dry weather
flow. The sludge that accumulates at the bottom of the clarifiers
will be moved to the OFS facility for processing. The
wastewater will undergo disinfection by chlorination, and the
effluent will be carried through a tunnel under the Harbour
floor; it will then be discharged from a diffuser in 30 metres of
water to the west of McNabs Island. This will result in a 66:j
seawater-to-effluent dilution at the Harbour surface.
The OFS process consists of dewatering and drying the
sludge, then heafing it to 450°C without oxygen. This yields an
oil product, a coal-like product called char, non-condensable
gases and ash. The oil product has several potential applications,
including use in the asphalt industry. Char and
non-condensable gases are burned in a fluidized bed furnace
to produce the heated air used in the sludge-drying process.
Ash will be disposed of in an approved manner.
2.3 THE ENVIRONMENTAL ASSESSMENT
REVIEW PANEL
The governments of Nova Scotia and Canada agreed that a
full environmental assessment review of the proposed regional
sewage treatment system was necessary. They realized
that two separate reviews would result in a great deal of.
duplication. Therefore, a joint review process was developed
to satisfy requirements of both the Nova Scotia Environmental
Assessment Act and Regulations, and the federal Environmental
Assessment and Review Process.
In November 1990, the Ministers of the Environment for Nova
Scotia and Canada announced the appointment of an independent
Environmental Assessment Review Panel, consisting
of Dr. Shirley Conover (Chair), Ms. Lesley Griffiths, Mr. Robert
Parker and Dr. Dan Thirumurthi. Biographies of the Panel
members are included as Appendix A.
The Panel’s mandate was, to conduct a public review process
to examine the potential environmental, social and economic
impacts of the design, construction, operation and maintenance
of the Halifax-Dartmouth Metropolitan Wastewater
Management System. The scope of the review was to include
the collection system, sewage treatment and sludge-handling
facilities, diffuser, and associated activities. In July of 1991 the
Panel received confirmation from the Ministers of the Environment
for Nova Scotia and Canada that controls at source of
wastewater quality and quantity, stormwater runoff, compliance
and effects monitoring, and cultural and heritage consid-
,/ erations were included in the Panel’s mandate. A complete
description of the Panel’s mandate and supplementary clarification
are included as Appendix B.
Two technical specialists were hired to advise the Panel. Dr.
Donald Hodgins advised in the area of physical oceanography,
including containment-dispersion and sediment transport,
and Dr. lsobel Heathcote advised in the areas of controls
at source, wastewater characterization and wastewater management.
Biographies of these consultants are included as
Appendix C.
2.4 THE REVIEW PROCESS
Figure 3 is a summary of the review process. As shown, input
from the public and interested parties was invited and incorporated
into the process at several stages, including preparation
of the Guidelines, review of the adequacy of the Environmental
Assessment Report and supplements, and public hearings.
Funding was made available to assist interest groups wishing
to participate in the review process. An independent funding
committee, administered by the Federal Environmental Assessment
Review Office (FEARO), assessed the applications
and in July 1992 a total of $128,500 was awarded to three
groups: Metro Coalition for Harbour Cleanup, Eastern Passage
& Cow Bay Ratepayers and Residents Association, and
the Williams Lake Conservation Company.
Guidelines for the preparation of the Terms of Reference for
an Environmental Assessment Report were prepared by the
Nova Scotia Environmental Assessment Administrator in consultation
with the Panel, interested federal and provincial government
agencies, and the public. These were finalized,
submitted to HHCI and made public at the end of March 1991.
HHCI prepared Terms of Reference to demonstrate the corporation’s
understanding of the instructions contained in the
Guidelines and to specify how it intended to meet the Guidelines’
information requirements. The Terms of Reference were
approved by the Nova Scotia Minister of the Environment in
June 1991.
HHCl’s Environmental Assessment Report was made available
to the Panel and the public on August 7, 1992. At this
stage of the process, two separate activities commenced simultaneously:
a review of the adequacy of the Environmental
Assessment Report by the Panel, and a technical review by
the Nova Scotia Environmental Assessment Administrator.