To step or not to step – that is the question: Sewer manhole step iron debate
Regardless of where you are in the world, there is likely a healthy debateon the need for manhole step irons. There are many opinions from design engineers, construction teams and maintenance teams about the usefulness of manhole step irons.
What are manhole step irons?
Step irons are installed in manholes to facilitate access to maintenance workers and/or aid self-rescue in the case of accidental entry into the sewer network. They are usually made of metal or plastic and are installed in manholes in a vertical alignment (think of a ladder) to allow people to move from the bottom of the manhole to the top of the manhole.
Manhole step irons
What is the debate about?
Originally, step irons were installed in manholes almost without exception. But with the ever-increasing focus on safety in the civil infrastructure industry, there are questions being posed about the need for manhole steps irons. The anti-step iron argument comes from the drive to use confined spaces equipment for entry into the sewer network, primarily a harness and tripod set up over the manhole that negates the use of step irons, in fact, they can sometimes get in the way of ease of entry/egress.
In regions that enforce confine space entry practices, entry to the sewer network is prohibited without the necessary training or equipment. So removing the need for manhole step irons has a case, especially when you consider the likelihood of associated ragging, corrosion and maintenance. To this extent, some authorities have gone to the lengths of cutting out manhole step irons form existing infrastructure.
Confined space entry manhole
The argument for keeping manhole step irons can be strongest in regions where manhole step irons don’t pose a significant maintenance burden, confined spaces practice is not as enforced, and/or illegal access to the sewer network is possible. The argument of self-rescue is a common reason for continuing to install the step irons. Similar to the ladders that you see installed on the edges of non-swimming water bodies, asset owners are obliged (sometimes legally) to provide a way for people to self-rescue in the event of an accident.
Summary
In summary, there is no set way to do things. The decision on whether to step iron or not should take into consideration a number of factors, not least of which a rigorous risk assessment to understand your options.
Have I missed anything? Leave your comment below
Has your organisation taken a position on new manhole designs, or feel free to share your personal thoughts – Iwould love to hear your feedback.
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“Data is not information, information is not knowledge, knowledge is not understanding, understanding is not wisdom”
– Clifford Stoll –
One of the significant changes for utility providers in the 21st century is the massive increase in data that is now available and streaming into organisations. It wasn’t so long ago that engineers were hand drawing pipe long sections and calculating maximum flows without the aid of hydraulic models, or even a computer. Those days are gone, long gone; the new breed of engineer now has access to a wide array of software programs, intelligent devices, and predictive tools that are all generating gigabytes of data for consumption:
Hydraulic models
Digital twins
Artificial intelligence processors
3D LiDAR mapping
Telemetry and remote SCADA Systems
Digital flow meters
Leak detection loggers
Overflow and pressure transient sensors
Multi-camera inspection robots
The result is the availability of more data than organisations have ever had in their history, and it continues to accumulate at a faster and faster pace each year. What hasn’t changed so quickly is the traditional skills that engineers are taught during studies and the types of roles that organisations create to look after their assets.
Turning data into information, and then using that information to make smart decisions and gain improved understanding of assets requires a different skill set than traditional engineers may be used to. Not only is more data coming in, but it needs storage, user access, and interaction among different software programs. Organisations that can successfully accept the substantial amounts of data and efficiently cleanse, analyse, and integrate it throughout their processes have a distinct advantage in providing services that return value for money and meet the objectives for their community or customers.
Taking advantage of Application Programming Interfaces (APIs) and integration options that are often market supplied and understanding the methods of detecting trends, risks and insights is a smoother process when organisations have data analysts on board who can be the key player to ensure engineers are working with information and knowledge and not just data.
Has there been enough discussion in the industry about the creation of these targeted positions and then attracting and keeping data analysts? Opening a dialogue with sector leaders and obtaining human resources buy-in that positions like this are essential, may be a different challenge, but one that is going to be worth taking on.
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Each year the Australian Bureau of Meteorology releases the National Performance Report for urban water utilities, the 2020-21 report is available for public download here: http://www.bom.gov.au/water/npr/
This annual report aims to provide benchmarking of pricing and service quality for urban water utilities. The report is helpful for utilities to monitor annual trends within their own organisations, as well as look at whether their key metrics sit within the typical range in a broader national context. Utilities are grouped within four size categories (small, medium, large, major). This reflects that revenue base and population density can be a factor in both the cost required to provide water and sewer to customers as well as the level of service that is appropriate or sustainable.
Running to 128 pages, this is a comprehensive report that lists metrics across 166 categories from 86 utilities. Dependent on your area of expertise or interest, there is interesting information for everyone.
Figure 1 – Australian utilities that submitted data for the 2020-21 report.
This article summary focuses on some of the key metrics that relate to gravity sewer mains and wastewater expenditure.
Sewer Main Breaks and Chokes
To enable comparative analysis, many of the metrics are reported as ‘per 100km of asset’, this is the case for ‘sewer mains breaks and chokes’.1 This last year has seen improvements for many locations with 57% of utilities reporting a decrease in breaks and chokes compared to the previous reporting year with Clarence Valley Council, Gippsland Water, and Gladstone Regional Council all seeing reductions of > 75%.
Utilities reporting the lowest instance of breaks and chokes in each utility group size is listed in the table below.
Table 1: Number of sewer mains breaks and chokes per 100 km (Indicator A14)
Utility Group
Utility
Value
Small (10,000 – 20,000 properties)
Water Corporation – Geraldton (WA)
3.4
Medium (20,000 – 50,000 properties)
Tweed Shire Council (NSW)
1
Large (50,000 – 100,000 properties)
Gippsland Water (VIC)
1.5
Major (100,000+ properties)
City of Gold Coast (QLD)
3.8
Major utilities saw the largest improvement for this metric. However, reductions were not the norm for small-sized utilities with the median increasing from 13.7/year to 15.6/year, and the average increasing from 25.3/year to 35.5/year.
Capital Expenditure per Property (Wastewater)
The report notes that the national median per property capital expenditure on wastewater services decreased by 11% from 2019-20 to 2020-21.
Utilities reporting the lowest wastewater expenditure per property in each utility group size is listed in the table below.
Table 2: Capital expenditure per property – wastewater (Indicator F29)
Utility Group
Utility
Value
Small (10,000 – 20,000 properties)
Gympie Regional Council (QLD)
$88.90
Medium (20,000 – 50,000 properties)
Dubbo Regional Council (NSW)
$3.65
Large (50,000 – 100,000 properties)
Power and Water Corporation – Darwin (NT)
$146.72
Major (100,000+ properties)
City West Water Corporation (VIC)
$143.57
Looking more closely at the data split by utility size, the average annual capital expenditure on wastewater is surprisingly similar across all utility sizes; in the region of $275 to $300 per property. The reported figures over the last decade do indicate that small and medium sized utilities may be investing less, on average, on wastewater infrastructure.
While there may be a variety of reasons for this, it will be of some concern if a trend of reduced investment is reflected in a similar reduction in wastewater service level KPIs (including sewer main breaks and chokes).
Figure 2 – Capital Wastewater Expenditure per Property
Despite the significant reported drop in per property wastewater expenditure over the last year (11%); the overall reported capital expenditure on wastewater has remained reasonably stable since 2017 at around $2.7 billion dollars per year – with a drop of 2.9% from 2019-20 to 2020-21 based on reported figures.
Figure 3 – Capital Wastewater Expenditure
Wastewater Operating Cost per Property
The report saw 66 of 86 utilities submit data on operating cost per property to supply wastewater services. The following utilities in each category reported operating their networks at the lowest cost:
Table 3: Wastewater operating cost per property (Indicator F14)
Utility Group
Utility
Value
Small (10,000 – 20,000 properties)
City of Kalgoorlie-Boulder (NT)
$168.96
Medium (20,000 – 50,000 properties)
Rockhampton Regional Council (QLD)
$294.59
Large (50,000 – 100,000 properties)
Toowoomba Regional Council (QLD)
$243.35
Major (100,000+ properties)
South Australian Water Corporation (SA)
$231.92
Residential Wastewater Bill
The cost to provide services is impacted by a wide range of factors, including but not limited to: age of assets, condition of assets, density of population, climate and topography. The table below lists the lowest residential wastewater bill in each category for the 20/21 period.
Table 4: Typical residential wastewater bill (Indicator P14)
Utility Group
Utility
Value
Small (10,000 – 20,000 properties)
Armidale Regional Council (NSW)
$465
Medium (20,000 – 50,000 properties)
Lower Murray Water (VIC)
$491.84
Large (50,000 – 100,000 properties)
North East Region Water Corporation (VIC)
$239.16
Major (100,000+ properties)
City West Water Corporation (VIC)
$347.92
The report indicates 57% of utilities had a reduction in the typical residential wastewater bill with Central Coast Council seeing the largest change (-24%). However nationally, the overall trend was only marginal (<1% decrease).
1 Wastewater mains breaks and chokes is intended to include:
Gravity sewer mains
Rising (pumped) mains
Low pressure mains
Vacuum system mains
It excludes:
Property connections
Treated effluent mains
Recycled water mains
It can be questioned whether failures on pumped rising mains and chokes within gravity sewer networks should fall under the same metric. While these asset types are intrinsically connected to form the majority of a sewer network, they operate under very different conditions and the mode and cause of failure are often quite distinct.
The information and data for this snapshot is sourced from Part A and Part B of the National performance report 2020–21: urban water utilities. It has been used under the Creative Commons Attribution 3.0 Australian License.
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The importance of the pipe network beneath out feet
Our cities and suburbs are supported by a vast underground network of water, wastewater and storm water infrastructure. This network of gravity pipes, pumps and filtration systems play a very important role in the quality of our life, eliminating disease, safeguarding the environment, and protecting communities.
However, parts of this aging infrastructure are nearing the end of its useful life and now (more than ever) requires closer attention. Without attention, this situation is not sustainable.
Most of our water and wastewater infrastructure were installed during the 19th century and municipalities are facing the challenge of broad-scale infrastructure replacements or repairs costing hundreds of millions of dollars.
Adding to all this is the changing climate factor, meaning systems that were designed 30 or so years ago may not be sufficient to support everchanging environment around it.
To extend the life of infrastructure, reliance on smart city technology capabilities is critical. By creating visibility into buried assets to understand the conditions of underground infrastructure, utilities can compare current performance with expectations, and predict when and where problems may arise. This also leads the way to prioritisation of maintenance work, decreasing downtime of the assets, resulting in reduced interruptions.
Today’s technology
With sensors and actuators becoming more cost effective, an array of technologies is becoming available for the pipe industry. For pressure pipes or pipes transporting materials under high pressure, static sensors are being used to help monitor the health of the asset. In sewer and stormwater applications, inspection by video still is widely adopted with assessment being carried out visually by an expert.
With operational technology (OT) and information technology (IT) coming together, data that were once only available in isolated networks is now available via the world wide web. What this means is CCTV operators are no longer needing to download inspection videos to a hard-drive in order to assess the condition of the pipe in the office, instead they can upload the video file over the cloud.
AI at your service
With more data being available and accessible, a path has been paved for advanced technology such as artificial intelligence or AI. These smart algorithms feed on data, in-fact, the more data that is available, the quicker and more accurate an AI system can become.
Like other technologies, AI is tool to better understand a problem so to make data driven decisions. One of the areas where AI is helping the pipe industry is in the field of video processing. The traditional means of CCTV condition assessment presents several challenges including time taken to review the videos and identify defects, the operator subjectivity and field conditions making visual inspections difficult.
The AI models are pre-trained to detect certain anomalies, in this case pipe features and defects. The inspection video is then ingested and inferenced against the trained model. The result is the identification of the type and importance of anomalies.
VAPAR’s AI
Integrating the above-mentioned technologies, the VAPAR.Solutions platform leverages cloud computing and its AI engine to automatically assess inspection videos that users upload. The platform is accessed via any web browser where videos can be uploaded, analysed, manually audited by an expert (if required), with a report generated and stored, eliminating the need for hard drives to back up the video data and corresponding reports.
With this approach, both asset owners and CCTV contractors are reducing the time taken for assessments, standardising the process to remove any subjectivity and utilising AI to deep dive into the data to get better outcomes.
In 2020, VAPAR worked with asset owners in Victoria, Australia, where the results showed that the solution outperformed the same inspection carried out manually. The AI algorithm missed fewer defects and was more accurate in grading the pipes. To date, VAPAR has processed over 3 million images, which means the AI has only become quicker and more accurate.
Industry impact
With the need for the pipe network needing special attention, technology is adding another lens to take a closer look. It’s empowering engineers, operators, and decision-makers to make data driven decisions more cost effectively and proficiently.
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