volume 1 - Halifax Regional Municipality

Halifax Water Integrated Resource Plan
Recommended IRP and Analysis
6.3.4 Growth Rate Sensitivity
The water and wastewater system planning activities were based on the baseline or
medium growth projections. A high level analysis of potential impacts and risks
associated with changes in growth rates was carried out. This analysis was used to
assess the variations in the Recommended IRP components.
The growth rates used in the analysis corresponded to rates developed for HRM 32 and
are as follows:
• High – 1.14%.
• Baseline – 0.81%.
• Low – 0.47%.
Based on these growth rates as presented above, there is about a 53% increase in
residential population to the growth horizon of 2046 under the high growth scenario
relative to the baseline and a 27% decrease under the low growth scenario relative to
the baseline. Assuming that the growth in future flows was proportionate to these
population estimates, an analysis was carried out on the requirements for the WSP and
WWTFs under these alternative growth scenarios. The smaller community facilities were
not included since significant growth in these areas was not expected. Bennery Lake
WSP and Aerotech WWTF serve the Airport and Aerotech Park and are subject to their
own growth requirements associated with employment growth, and are not included in
this analysis.
Table 6.3 presents the results of this high level analysis. The table shows that under the
high growth scenario, the WSPs will not require expansion but towards the end of the
30-year planning period will require additional water supply because the supply safe
yields will be exceeded. Continuing climate change, which may reduce supply, could
exacerbate this. A new program has been proposed to assess impacts of climate change
on all systems, update design standards, update operational practices, and integrate
findings into Water and Wastewater Master Plans and Wet Weather System Plan. At the
same time, these estimates do not account for the continuing reduction in water
demand. Considering the reduction in demand is 1.5% after taking into account growth,
this may well negate any impacts of an accelerated growth scenario. The low growth
scenario would be comfortably within plant capacities and safe yields.
The WWTF expansion requirements are based on the combined impact of WWTF
consolidation as well as growth as developed under the RWWFP. The impact of
accelerated growth would be two-fold. It would move forward the expansion
requirements at the Dartmouth and Herring Cove WWTFs and would increase the size of
the required expansion. Again this analysis does not consider the impact of water
32 Employment Population and Housing Projections Halifax Regional Municipality: and
Update, Altus Group, July 2009
Revision: 2012-10-29 Integrated Resource Plan 87
October 31 2012 Page 120 of 272