volume 1 - Halifax Regional Municipality

Halifax Water Integrated Resource Plan
Integrated Resource Plan Development and Evaluation
the current overflow control program at the B Level corresponding to 10 years was
felt to be reasonable.
• The difference in 30-year NPV based on the Baseline and Enhanced Overflow
Control Programs (e.g. Plan 15-3 versus Plan 22-3) was $71 million. The Enhanced
Overflow Control Program does further reduce environmental impacts for the
additional cost.
At this stage in the alternative resource plan development and analysis, the 30-year NPV
is similar for all plans. The differences largely lie in the level of environmental and public
health impact.
Based on the analysis presented above, it was decided to short-list four of the refined
plans. The analysis of the refined plans is discussed in the next section.
5.11 SHORT-LIST PLAN ANALYSIS
The four short-listed alternative resource plans are presented in Table 5.11. The NPV of
cost difference between the most and least is $121 million over the 30-year period. This
difference is comprised of approximately $71 million difference due to the Enhanced
Overflow Control Program and a $50 million difference due to the compliance timing for
the Enhanced Nutrient Removal Program.
Table 5.11
Short-Listed Alternative Resource Plans
Plan No.
30 Yr. NPV
$million
Current WWTF
Current
Overflow
Future WWTF
Nutrient
Future Overflow
21-4 $2,458 B B B
38-4 $2,507 B B A
28-4 $2,529 B B B
40-4 $2,579 B B A
Baseline
Enhanced
The timing of the current WWTF compliance program and the current overflow control
program has already been discussed under the refined plan analysis. The remaining
decisions in connection with the short-listed plans are associated with the timing of
nutrient control implementation and the level of future overflow control.
As far as nutrient control timing is concerned, there is a $50 million cost increase for a
program with a 10-year timetable compared to a program with a 20-year timetable.
The expected benefits of the Enhanced Nutrient Removal Program by way of reductions
in N and P loadings are shown in Figures 5.7 and 5.8. For illustrative purposes, the BLT
and Mill Cove plants were not included in this analysis but would also have substantially
reduced loadings with the Enhanced Nutrient Control Program. It should also be noted
that operating permits for the WWTFs currently do not have total N limits.
Revision: 2012-10-29 Integrated Resource Plan 73
October 31 2012 Page 106 of 272