When the problem is so big, where do you start? Renewals to meet your budget

Nicola Whelan-Henderson & Rico Parkinson - Stantec

Many engineers would consider pipe renewal boring and simple; it is hard to get people
excited about a typical 150mm wastewater or watermain that is to be buried under the
ground for 100-years and hopefully never seen again. It is no wonder that we have such
a massive infrastructure deficit when there are so many other, more exciting projects that
are crying out for money from local councils.
There is a consensus that a change in how we approach renewals is needed. However, with
such a massive deficit of asset renewals to date, limited funding, and no significant change
of approach in the last 10 years, it is hard to see a way forward. Two things come to mind
when I think of renewals, the first is a Bart Simpson quote, “Let me get this straight: we're
behind the rest of our class and we're going to catch up to them by going slower than they
are? Coo Coo!” and the second is a simple proposition from a work colleague who said to
me “at the current investment level in renewals we will complete the current replacement
of all assets that last 100 years in approximately 1000 years”. These might be an
exaggeration but have truth at the heart of them.
At Stantec we help clients around the world with the “bread and butter” work of pipe
renewals. In many cases, we come on board when trying to determine where best to spend
the money when the list of pipes requiring renewal (pipes recorded as in poor condition or
simply pipes known to require constant repair) significantly exceeds the budgets available.
Clients come to us asking “when the problem is so big, where do we start, how do I get
the most bang for my buck?”.
This paper will outline some recent approaches Stantec has carried out to help scope
renewals to meet the available budget. The first is an example from Wainuiomata,
Wellington, where the condition has been predicted but performance a little less known.
The second is from the United Kingdom, where pipe performance history is known but the
condition is not. In both cases, we identified and designed a renewal programme of selected
pipelines that could be carried out efficiently to achieve an immediate reduction of pipe
breakages and customer outages while matching the available limited budgets.
For the work in Wellington, we trialled a selection process that has been automated using
open-source data to enable repeated application for future use in other areas to create a
“Long List” ready for review and refinement with client and contractor to help maximise
renewal impact to meet the available budgets. These approaches allow clients to have an
‘on-the-shelf’ ready design they can refine to suit their budgets while maximising renewal
length to achieve the best bang for their buck