volume 1 - Halifax Regional Municipality

Halifax Water Integrated Resource Plan
Integrated Resource Plan Development and Evaluation
The asset renewal program evaluation in the IRP was conducted in two steps. Initially,
three levels of asset renewal were considered for all point and linear assets. The levels
of asset renewal for point assets were:
• A – 0.8 x asset service life
• B – 1.0 x asset service life
• C – 1.2 x asset service life
The levels of asset renewal for linear assets were:
• A – Decreasing average asset life at end-of-period
• B – No change in average asset life at end-of-period
• C – Increasing average asset life at end-of-period
These levels (A to B to C) notionally corresponded to an increasing risk of not meeting
LOS and IRP objectives. The first stage of the IRP analysis explored the above monolithic
risk level for all asset systems (i.e. water, wastewater and stormwater) and all asset
classes within each system (e.g. water – distribution mains).
Asset renewal requirements were generated using a proprietary asset renewal model.
The asset renewal model evaluated the age of every asset at every model time step and
then compared this age with service life of the asset. If the age in the time step
exceeded the service life of the asset, the asset was replaced. Ideally, replacement
decisions should be based on asset condition information not just on service life alone.
In actuality, an asset management program would employ a range of interventions from
repair through rehabilitation to extend asset service life rather than always replacing
assets at their service life limits. However, given the limitations of available asset data
(see Section 4), service life was used as a reasonable surrogate.
This analysis was carried out for each year of the 30-year planning period from 2013 to
2043. This provided a year-by-year asset renewal program cost, which was incorporated
into the overall financial model.
The details of the asset renewal modeling procedures used to estimate the asset
renewal costs are presented in Volume 3 Appendix E.
As is explained later in this Section, the initial and intermediate alternative resource
plans used the A, B, C analysis described above. Later in the formulation and evaluation
of alternative resource plans it was decided to use asset specific risk based renewal
rules for each asset type. The resulting overall asset renewal strategy was designated as
“composite” since it was formed from the individual asset strategies.
Revision: 2012-10-29 Integrated Resource Plan 51
October 31 2012 Page 84 of 272