volume 1 - Halifax Regional Municipality

Halifax Water Integrated Resource Plan
IRP Planning Context and Levels of Service
leader flows. This program relies on reaching a cost sharing solution with HRM and
the benefitting ratepayers.
• The update and expansion of the wastewater system model as well as additional
sewer system data collection with incorporation into GIS that will provide improved
decision support tools to update the evaluation of alternatives in the RWWFP.
• The revised planning projections that are being developed in the Regional Plan.
• Updated wastewater system design standards and allowances including a realistic
incorporation of future climate change impacts.
It is for these reasons that the IRP recommendations address a revamped approach to
system master planning. This would involve key component activities such as an I/I pilot
program upon which the business case for wet weather flow reduction program could be
developed. The wet weather flow reduction program would then form one of the key
components of a Wet Weather System Plan integrating all the aspects of wet weather
flow and overflow management along with climate change. These in turn would be
brought together with other collection system needs such as asset renewal and the
WWTF expansion/compliance requirements into a Wastewater System Master Plan. The
water system would adopt a similar approach with key components such as the WQMP
and transmission main program integrated into a Water System Master Plan. The
proposed planning approach is presented in Section 7 under the IRP Implementation Plan.
Collection System
As noted in the introduction to the wastewater system, the present collection systems
include areas of combined and separated sewers as well as separated areas that are
strongly influenced by wet weather due to historical household connection practices.
The topography and geography of the HRM has necessitated extensive use of pumping
resulting in 172 wastewater pumping stations. Many of these stations as well as the
WWTFs are subject to substantial wet weather influence with wide swings in flow rates
resulting from rainfall or snowmelt. This has resulted in numerous designed and some
unintentional locations that allow excess wastewater to overflow during wet weather.
Based on data collected by Halifax Water there are presently a total of 216 known
potential overflow locations within the wastewater system approximately 105 of which
are known to have been active at any time. Twenty-nine (29) of the 105 active overflows
locations are associated with the combined sewer system.
The RWWFP modelled a total of 96 of the potential overflow locations and determined
based on the modeled results, 59 overflows are active during a year with average
rainfall. The RWWFP modeling further determined that 28 of the 59 overflows active
during an average rainfall year would be impacted by future growth. The RWWFP
includes measures to control only those 28 overflow locations that are expected to
Revision: 2012-10-29 Integrated Resource Plan 25
October 31 2012 Page 58 of 272