Young Opus engineer Jules Scott-Hansen says one of the biggest challenges for her generation may not lie in building new assets but in looking after what we already have. Christchurch’s Land Drainage Recovery Programme marks a significant step in that direction.
Asset management puts me to sleep” was the blunt response I got from one of my more senior colleagues when I asked him to review my first ever conference paper for the Water New Zealand conference back in 2015. There I was, a civil engineering graduate of not even an entire year, experiencing my first case of what I like to call ‘prengidice’ – a term that describes an engineer who conceives their work to be superior to other engineers.
Let’s be honest, asset management isn’t exactly what young engineering graduates dream of when they picture themselves making their first steps along the path of their new careers.
Building windmills, designing bridges, harnessing natural powers? Yes. Trawling through spreadsheets and developing algorithms to estimate the remaining useful life of existing infrastructure? Maybe not so much.
Albeit, my first two years of working as a three waters engineer were largely spent collecting, QA-ing and analysing data on stormwater assets. Dreams of saving the world aside, throughout this work I began to develop an appreciation for what may be one of the biggest challenges for my generation of engineers: not building new, but looking after what we already have. And hence, the sleep-inducing term ‘asset management’ looks like it’s here to stay, regardless of its eng-appeal.
Now if ‘asset management’ strikes a dull chord amongst the self-proclaimed professionally superior, then adding ‘stormwater’ to the title is not increasing your chances of capturing the interest of the three waters sector. Historically, in New Zealand making the case for continuous stormwater management has been harder than for other asset classes.
Issues are compounded by a lack of national consistency and unclear guidelines for appropriate levels of service (LoS). Stormwater management inherently does not promote long-term and continuous investment from politicians due to the somewhat unpredictable and intermittent nature of events.
Christchurch land drainage
The Christchurch story makes a good case for the importance of continuous stormwater management. Following the Canterbury earthquakes throughout 2010 and 2011, the city’s land drainage network was significantly affected. This was primarily in three ways:
- Ground movements caused widespread differential settlement to the land throughout most of the city;
- Violent shaking caused the ground to liquefy, bringing large amounts of silt to the surface which deposited and built up throughout the channel beds; and
- Damage to infrastructure was extensive which limited flow and created hydraulic restrictions.
The initial response following disastrous events such as those experienced in Christchurch usually focuses on the immediate necessities of communities such as access to safe and clean water, electricity and shelter. Investigation and repair of the stormwater network is, understandably, lower down the priority list until the subsequent results of neglect present themselves in the form of water throughout streets and properties, as occurred in the rain events of March / April 2014 which drew significant media attention.
So with stormwater finally on the agenda, it was time to put together a repair and remediation strategy. However, with Christchurch’s more than 700 kilometres of extensive land drainage network, knowing where to prioritise the first efforts was no simple question, and it was apparent that extensive data collection and condition assessment was required.
The asset management journey for any asset class begins with understanding what you have, and preferably also what condition it is in. Data is fundamental to asset management and evidence-based decision-making; data that is collected and managed appropriately allows us to make powerful arguments and optimise our investment decisions. In the case of stormwater assets, this not only leads to reduced spending but can also have positive effects on social, cultural and environmental values.
In Christchurch an extensive data collection process was initiated by the Land Drainage Recovery Programme (LDRP). The in-field data collection took place over a period of roughly two years throughout which around 27,000 data points were collected. The data collection focused on four main attributes:
- Attribute and condition data of open channels – 425 kilometres assessed;
- Five values assessments (culture, ecology, heritage, landscape and recreation) – 380 kilometres assessed;
- Attribute and condition data of structures associated with the network – 8200 structures identified; and
- Faults and damage assessment – 9500 faults identified.
Life after data collection
Once the data collection was completed and the data pool was rich and plentiful, the next challenge lay ahead: using the data for understanding the level of damage on a city-wide scale and developing repair programmes and prioritisation.
One of the biggest challenges lay in differentiating between damage that was caused directly by the earthquakes and that which was caused by business-as-usual (BAU). Faults were categorised as one or the other in the field surveys but many cases were subject to uncertainty around the primary cause of damage.
It is particularly difficult to make sound judgements on the effect of pre-existing damage when there is limited pre-earthquake data with which to make comparisons. Having a comprehensive asset database will also help asset managers understand deterioration of assets under ‘normal’ circumstances, in particular if data collection is carried out regularly, eg every five years.
As mentioned, the LDRP data collection focused on differentiating between reduced performance levels and damage caused directly by the earthquakes or through BAU. On a city-wide scale, around 15 percent of faults were identified as being directly caused by earthquake damage. This number was significantly lower than expected and again highlighted the importance of continuous assessments as well as thorough maintenance regimes and accessible feedback systems for the maintenance contractors.
One insight that arose from analysis of the data was that earthquake-related damage was significantly more prevalent on the high severity faults; overall the Severity 5 (catastrophic) faults were caused by earthquakes in 50 percent of cases, whereas the lower severity faults were only caused by earthquakes in around 15 percent of cases (see figure 2).
In addition to the primary purpose of assisting the LDRP team with earthquake recovery efforts, there have been several other benefits. These include:
- Using the data to support operational purposes;
- Identifying a number of compliance issues;
- Identifying critical asset failures that may otherwise have gone unnoticed for a long time;
- Making the case for continued condition assessments and understanding more about what is involved in undertaking this type of work; and
- Improving the quality of the data that goes into valuation and criticality activities to create hard-evidence-based outputs.
One of the hopes is that the LDRP dataset will continue to create wider benefits and be used to support further activities within the Christchurch City Council. The applicability of the dataset is inherently limited as it was instigated as a ‘rapid fire assessment’ to enable works to progress within the LDRP team.
Subsequently, as the dataset was specifically targeted towards a specific purpose, it is perhaps not comprehensive enough to support other causes for example within the three waters and waste asset management team. But the dataset provides us with a good starting point for doing gap analyses and determining what further data collection is required.
The data can also be used to help develop deterioration curves for different construction styles and materials. This activity will also be significantly improved if a rolling programme of assessments is set up.
The hope is also that the LDRP dataset can tie in with ‘future’ technologies such as real-time data and instant user feedback both from the public and maintenance contractors. This type of direct input can create immense benefits for the operations team in terms of highlighting issues before they become an actual problem.
The LDRP dataset is significant in terms of its scale and comprehensiveness from a local perspective in Christchurch. It is probably the first time that the Christchurch City Council has had access to such an in-depth view of an asset portfolio that was in need of some attention.
So data collection is important, but proper analysis and implementation of the data is even more important, and the LDRP dataset provides a good example of what is hopefully an initial step for an exciting future of improved stormwater management at the council.
On a national scale, the New Zealand Metadata standards will provide national standards for how data is captured, described and stored. The standards, which cover three waters assets, roads and buildings, will enable data consistency which will ultimately support decision-making and increase collaboration across sectors.
The standards are also key to achieving the 2015 Thirty Year Infrastructure Plan which aims to create infrastructure that is resilient, coordinated and contributes to a strong economy and high living standards for New Zealanders.
The full data summary report from the data collection is available on Christchurch City Council’s website: bit.ly/JulesScottHansen. Jules Scott-Hansen is an environmental engineer at Opus International Consultants. email@example.com
This article was first published in the November 2017 issue of NZ Local Government Magazine.