pipeinspection

Targeting the Correct Pipe Slope

Why is pipe slope important?

Most wastewater networks rely on gravity to function. The term ‘💩 runs downhill’, wasn’t coined by accident. Interconnected gravity sewer pipes collect flow from customers and transport the wastewater downstream to a treatment plant through a series of gravity pipes, pump stations and pumped mains.

When designing new gravity sewer mains, the ground topography and required grade of the sewer is the driving factor in determining where it will be constructed and how deep it will need to be. A sewer that is too steep will result in fast flow and increased turbulence. A sewer that is flat or has a sag (belly) is problematic and likely to result in ponding water and a build-up of sediments and solids. This gradual build-up of deposits can create blockages and overflows.

Figure 1 – Problematic flat spots in a pipe

Different ways to measure pipe slope and straightness?

Following the construction of a new sewer, a range of tests and checks are carried out to ensure it has been constructed as per design and is fit for purpose. These checks can include an air pressure test, hydrostatic test, ovality test, and pipe grade check.

Utility organisations, who are the owners of the pipes, may use a variety of methods to be satisfied the new pipe has been constructed to design by housing developers or contractors. These tests check to see if the pipes are straight, free from obstruction and will achieve self-cleansing velocity. Tests can include:

Ball Test
A smooth ball is placed at the upstream end of the sewer pipe and should run unobstructed to the downstream end.
Light & Mirror Test
A light and mirror are sometimes used to ensure a new sewer main is straight with no unintended horizontal or vertical bends. The projection of a strong light through a straight sewer can be confirmed with a full circle of light visible at the end.
Dynamic Inclination
Many CCTV camera crawler systems come with inclinometers that will display the grade of the pipe directly onto the inspection video. Sections of the pipe that are too flat or have a sag/belly can be identified from this displayed value.

Figure 2 – Digital inclination recorded by a CCTV crawler

An out of the box solution!

On a recent trip to the USA, the VAPAR team discovered an out of the box solution from a pilot project in Oregon. The City of Salem have been using an alternate inclination testing approach for decades. It has worked so well for them; they continue to use this unique method to check new pipe meets their requirements. Just prior to the CCTV pipe acceptance inspection, tracing dye is released into the pipe to be tested. If the pipe has a consistent negative slope the dye will not collect and pool in a sag. If there is a pool of dye, then there is a sag present, but the dye will not be able to quantify the magnitude of sagging.

The method employed by City of Salem is novel in its ability to identify and quantify a sag in a pipe. A target is installed in front of the CCTV camera that clearly identifies if a sag is present. The magnitude of the sag can be observed using a target where the rings correspond to their internal acceptance levels. Any significant sag in the pipe is immediately obvious as the dye level will reach the 4th target ring.

Figure 3 – Crawler camera with dye target mounted out front

When the pipe doesn’t meet the required slope

If there are a number of these instances of this occurring, it may trigger a complete pipe relay. A single instance where the dye reaches the 5th target ring will generally require a dig-up to address the sag and remove the risk of settling deposits and blockages. In-service pipes with sags/ponding often require regular jetting to minimise this risk.

Figure 4 – The City of Salem target

Evolution of ideas

The team at the City of Salem are an excellent example of not limiting the approach to a problem or task with a narrow and set method, but rather to think about the job at hand and include innovative ideas to achieve a desired outcome. Testing alternate equipment, technology, and methodologies is an important part in process evolution throughout the world.

We would love to hear from others who have a unique solution to complete a part of their job!

About the Author

Mark Lee is the Business Development Manager (Aus/Nz) at VAPAR and a former Senior Asset Engineer who has spent more than a decade managing the asset lifecycle of infrastructure. He has extensive experience managing pipeline networks, including design, construction, condition assessment and decommissioning.

Learn more about Sewer Network

VAPAR automates sewer and stormwater pipe condition assessment for councils, utilities and CCTV contractors. Learn how we help improve the monitoring and maintenance of the underground pipes using AI.

Click Here

Increasing the value of wastewater network monitoring

Innovation is the key to delivering ever-increasing performance

Asset owners around the world are looking for innovative ways to deliver on the challenge of increasing wastewater network performance targets. With improved technology and the ability to handle large amounts of data, it’s become significantly easier to monitor flow and depth patterns, and highlight issues within a network that trigger a maintenance response prior to a flooding or pollution incident occuring.

Radar level and IoT telemetry device from Metasphere (Sense Level, ART Sewer)
Wastewater monitoring can generate a return on investment when they prevent flooding and pollution incidents.

Of course, there is no point in installing monitors for the sake of it, they should be positioned so that they have the greatest value. Having monitors in areas that don’t generate a return on investment is not prudent, therefore knowledge of current system performance and planning is required to determine the optimal locations that will provide a positive return when installed in locations that are most likely to prevent flooding or pollution incidents.

The most important part of the puzzle in locating monitors is to understand the characteristics of the most common failures within the network; blockages. A previous UKWIR project identified the following:

20% of blockages reported over a year are repeats at property level and this increases to between 40% and 60% when analysed at the postcode level.
The proportion of repeats increases to 30% and 70% at a property and postcode resolution respectively when there are 5 years of data available.
Approximately 50% of postcodes and 4% of properties have suffered 1 or more blockages over a 9-year period, this reduces to 23% of postcodes and 1.2% of properties suffering repeat blockages over the same period.

Analysis of historic blockage data indicates blockages repeat at the same location over time.

This analysis shows repeat blockages happen at the same location and that if monitors are located correctly, they can be effective in preventing major incidents.

The report also identified the most common causes of blockages: high density of interceptors, high densities of FOG (fats. oils & grease) generating properties, older properties, terraced / high rise properties, small diameter sewers and lower affluence.

This suggests that taking remedial action such as removing interceptors, root cutting, repairing structural defects and educating customers about the use of FOGs and wet wipes would mitigate the probability of repeat blockages. Fixing the root cause will prevent having to constantly reattend to carry out blockage clearance maintenance, which causes inconvenience for the customers and increases operational costs.

In a perfect world asset owners would repair and replace all the defects in a wastewater network. The reality of course is there is no bottomless pit of money for this activity and funding will continue to be challenged given the current focus on the affordability of utility bills.

The affordability challenge associated with utility bills means there will never be sufficient funding to repair all defects on the network.

Repairs are not always practical or cost effective

This is where asset management comes in and provides us with the capability to effectively balance the cost, risk and performance triangle depending on the objectives of the asset owner. For example, In the case of complicated wastewater networks that may run beneath buildings with a flat gradient that increases the blockage probability, then the implementation of a proactive cleansing programme is likely the best approach to balance cost, risk and performance. The use of monitoring in these situations allows the proactive maintenance costs to be optimised and ensure cleansing is only completed when it is required.

Asset Management provides the capability to balance the cost, risk and performance triangle to deliver the asset owner’s objectives.

Alternatively, the installation of a monitor where roots have been identified or where a partial collapse has occurred is unlikely to balance the triangle correctly. It will likely be more efficient to mitigate the root cause (e.g. cut out the roots or repair the collapse) compared to monitoring the location.

Data is key to making informed decisions

The ability to adapt the correct balance of cost, risk and performance for each scenario is based on having the right data available to understand the root cause of a flooding or pollution location. Using CCTV pipe inspection data provides the ability to understand the root cause and enables monitors to be installed at locations where they can generate the greatest Return on Investment (ROI). The historic challenges with CCTV pipe inspection data have been its cost (e.g. it is not cost-effective to survey the entire network) and the ability to provide the outputs in a format that allows good investment decisions.

VAPAR uniquely combines Artificial Intelligence, the latest software capability and human input, reducing the cost of CCTV pipe inspections and making the outputs more accessible to decision-makers. Reducing the cost of CCTV pipe inspections makes it more economical to either complete CCTV pipe inspections prior to installing a monitor or use existing inspection data as part of the monitoring decision-making process. A great example of making the CCTV pipe inspection data more accessible is the visualisation of the survey results via a GIS, where the defect locations can be understood relative to the proposed monitor location on the pipe network.

VAPAR’s capability to visualise CCTV pipe inspection data allows monitoring locations to be identified that will deliver the greatest ROI.

Conclusion

It is fundamental for Asset Managers to look at alternate and innovative ways of managing pipe networks if they are to deliver the increasingly challenging financial and performance targets. The use of network monitoring provides one of these innovative ways, however, it will not provide a ‘Silver Bullet’ in isolation. The use of VAPAR alongside monitoring will allow CCTV pipe inspection data to inform the decision-making process on where to install monitors. Ultimately this will balance cost, risk and performance and ensure the return on investment from monitoring is realised.

Local Sewer History Finds

Keeping an eye out for local sewer history finds

Most major cities had their first sewer infrastructure constructed centuries ago. While much of the original networks are either long gone or buried deep underground, if you do a little research and keep your eyes open you’ll likely find some interesting structures that formed part of the original systems. In some cases, these will be decommissioned, others are still in services hundreds of years after they were built.

Sewer aqueduct spanning Johnstone's Creek (Annandale, Sydney)

Finding a piece of Sydney’s sewer history

Out on a recent morning jog in Annandale, I came across a sewer aqueduct that was partially enveloped by the canopy of a large fig tree. Reading the faded plaque on one of the concrete arch supports and reading up on its history, it was interesting to learn about the important role this structure played in the early Sydney sewer network.

The Johnstone's Creek Aqueduct

Designed by Prussian engineer William Baltzer and constructed by Carter, Gummow and Forest in 1896, the aqueduct contains 8 primary arches and has a total length of 281m. It was the first use of reinforced concrete for a large structure in Australia. This very new construction technique of the time was under patent and known as the Monier system. The historical significance of the Johnstone’s Creek aqueduct has led to it being listed on the NSW State Heritage Register.

Early example of reinforced concrete in Australia

Transporting sewage to Bondi

The separation of the Sydney’s combined stormwater and sewer pipework began in 1887, and by 1889 the Sydney sewer network had reached 140km of pipe and was servicing close to 25,000 properties across the inner city. With this flow discharging into the harbour, construction of more sustainable options had been underway for some time. Construction of the Bondi Ocean Outfall and Botany Sewage Farm was completed in 1889 and allowed for further expansion of Sydney’s sewer network.

This included the Northern Main Sewer which would service the growing population in Annandale and Balmain and transport flow to a main line junction at the corner of Parramatta Rd and City Rd, then all the way through to Bondi. This extension required crossing both Johnstone’s Creek and White’s Creek with the construction of aqueducts the most suitable design option of the time.

Could reinforced concrete be trusted?

In the late 19th century, the idea of using concrete for such a large structure was not without detractors. The original Public Works Department design called for a brick arch construction and the submission for this new design and material had initially been rejected due to its experimental nature and unproven history. However, support from Robert Hickson (Under-Secretary for Public Works) was interested in trialling the use of reinforced concrete and what was an innovative idea at the time. The Monier design delivered spans that could be 50% larger than brick, and the total cost of the project was quoted as 20% cheaper – it received the go-ahead for construction after test arches were loaded to failure at Burwood with positive results.

Looking west from Glebe to Annandale showing construction of Johnstons Creek Sewer Aqueduct. (City of Sydney Archives)

The rest is history

It didn’t take long before the advantages of reinforced concrete led to a rapid increase in use for a wide range of structures. The first reinforced concrete water reservoir was built in Kiama just a few years later in 1899. The Annandale Aqueduct has certainly stood the test of time, it required only minor maintenance in its first 90 years of service – far exceeding the 3-year guarantee period. The flume was eventually plastic lined in the 1980s and the arches underwent repair and protection works in 1996.

Still interested in more of the aqueduct’s history?
Well, there was some controversy!

Like any good historical story, the construction was not without controversy. A Royal Commission was held in 1896 and ran for over a year. It was based around accusations of favouritism, contract violations, and defective work. This was not assisted by the fact that at the time William Baltzer suggested the alternate design he was working as a draughtsman in Sewerage Construction Branch of the Public Works Department while also on retainer as an engineer for Carter, Gummow and Forest who were awarded the contract. Despite the large furore and public investigation, the final report fully exonerated Hickson, Baltzer and others involved. It even went as far as finding that some of the allegations appeared frivolous and not founded in truth. As difficult as this must have been for the engineers and others involved in the commission so soon after construction, it is the detailed record of the commission that has provided such informative history and detail about the project from inspection to completion. It was the commission proceedings themselves that meant this significant construction achievement become one of the best documented contracts of the era.

Extract from the Public Works Inquiry Commission

VAPAR.Solutions is designed to process and score video footage from a wide variety of camera systems, providing a single cloud-hosted location for all your inspection videos, images, reports and decisions.

Opportunities to improve the UK pipe inspection standard (MSCC5)

Introduction

If you work within the UK water industry, you will be very aware of the MSCC5 (Manual of Sewer Condition Classification Fifth Edition). The first edition dates back nearly 40 years now, and in that time, many hundreds of thousands of miles of sewers and pipes by thousands of different contractors of all shapes and sizes have used the code to create a standardised output.

Is history holding back the future?

The Water Research Centre (WRC) first published MSCC back in 1980, and since then, other countries have adopted the idea behind a standard. This led to the creation of the European Standard BS EN 13508-2:2003+A1:2011, which has allowed the different codes to use a common language.

This alignment now presents a challenge with updating MSCC so it can keep pace with the technological changes. The need to align with the European Standard means many stakeholders will need to agree to any changes. However, there is a real need to update the standard, given that the current manual is still referring Cathode-Ray Tube (CRT) screens and their calibration. Is there anyone out there using these screens now?

MSCC5 references the calibration of Cathode-Ray Tube screens. Does anyone else still use these screens?

The first opportunity to improve the standard is to consider what the future of pipe inspecting coding might look like and how MSCC can support the future. We feel that using AI and modern software techniques is the first step in modernising a sector that has not changed significantly in the last 40 years.

Can the pipe inspection industry be modernised to deliver the benefits generated by the latest manufacturing plants?

How could we look at things differently?

So, what could a new coding standard look like in 2022 if we were designing it from scratch? If you look at computer software these days, it is a lot simpler than it used to be. Less is more now, and even the most complicated programmes have simple user interfaces to help speed up workflow and productivity. Gone are the days of needing to install desktop software and then updating it physically.

So how can this be applied to sewer surveying and classification, given that there are different types of users, from Water companies to small drainage contractors?

We need to think about why we are doing the survey and what is the result we want. The purpose of the standard is all about making an informed decision about investment in repair, maintenance, or renewal in line with its condition, serviceability, and budget available. Does the current coding standard meet the requirements? If yes, does it do it with simplicity in mind? This factor is essential when training people on how to code and survey? With so many codes and conditions to learn, this can extend training requirements and take years for operatives to gain all the experience needed to code the surveys to the exacting standards. Are contractors doing this, and is it possible to audit it accurately – probably not!

By simplifying and determining the key elements that make up the investment decision, we could remove a lot of unnecessary work and time and use enhanced technology to fill in the gaps speeding up workflow and productivity and saving money. The delivery of this outcome could start with a single document containing the coding and scoring requirements. Currently, MSCC5 includes the codes, and the Sewer Risk Manual holds the scores to determine the condition grades that typically drive the investment need.

Coding observations

Do the current set of codes consider all likely defects on the network? Is coding of infiltration, H2S attack and Hydraulic overload accurate and in a way that informs decisions on the action necessary. We don’t currently have a condition grade that reflects the degree of infiltration associated with an asset.

Abandoned surveys require a comment in the remarks section to explain the root cause for the survey being abandoned. This approach is not helpful when you own a survey company and are looking to minimise the number of abandoned surveys and increase your productivity. How do you determine the value of providing the crews with longer cable lengths to minimise the number of ‘out of cable’ abandonments? In other countries, they have specific abandoned codes related to the defect before. For example, the Australian manual has ‘Survey Abandoned Collapsed Pipe’.

How many abandoned surveys occur due to insufficient cable length?

Open and displaced joints always cause much debate and can be confusing 5-10% of diameter gets a score of 40, but 1.5 pipe wall thickness receives a score of 2. Typically, a pipe wall thickness equals 10% of the internal pipe diameter, so how can this be made more consistent?

Condition Assessments

We have a situation where we have two different types of condition assessment criteria in the UK. There are two scoring systems; the DRB Drain Repair book grades A, B & C (for domestic properties) and the SRM (Sewer Risk Management grades 1-5) on some software systems. Whilst they map against each other, it seems questionable to have two different approaches. It is essential to have accurate data to make informed decisions, and having one standard will make that accuracy more consistent. This further help simplify the training and reduces the costs for survey company owners.

Furthermore, is it also possible to be more scientific about the likelihood of further deterioration or collapse? Given that we have years of data, is it possible to develop a more accurate way of assessing risk on specific pipe lengths? Could this allow us to plan repair and maintenance more productively and head off issues at an earlier stage with a more cost-effective repair? We suspect the disparate data storage capability of the incumbent software applications for pipe inspection coding means this will be difficult. However, VAPAR’s central database of pipe condition assessments allows this type of data to be easily accessed and could be the key to unlocking a faster and more cost-effective solution to surveying and condition assessment.

Final thoughts

Technology plays a massive part in all our lives; whilst CCTV camera technology has advanced exponentially over the past ten years reporting systems have remained static. The traditional processes are still heavily manual and require extensive training and experience to keep the data collected consistently. But are we now at crossroads in terms of the old and the new?

VAPAR‘s AI platform is now able to generate MSCC5 compliant outputs. The development work to comply with MSCC5, plus the standards used in Australia, the United States and New Zealand, has provided us with a unique perspective.

VAPAR’s modern and unique capability to combine AI and human inputs to produce a fast and accurate output provides an opportunity to match the latest CCTV camera technology. Updating the MSCC standard is one part of the puzzle that will significantly improve how we do things for the customers using piped networks.

Vapar provides the capability to combine AI and human inputs to produce a fast and accurate output and provides an opportunity to match the capability of the latest CCTV camera technology.

Different Types of Pipe Inspection Cameras

The inspection of sewer and stormwater networks is commonly completed using a camera that records video footage from the inside of underground pipes also called the pipe inspection camera. The photos and videos collected during a pipe inspection can be used to assign a condition grade to pipes through the identification of structural and service defects. Councils, municipalities, and water authorities use these condition grades to prioritise pipe maintenance (e.g., clearing roots and debris) and repair (e.g., patches and lining).

Access to pipes is usually obtained through maintenance holes or pits which can be located within roads, kerbs, public space, and private property.

A variety of different camera equipment is available to record video footage for defect analysis and scoring. Common pipe inspection camera types include:

Crawler Cameras

Crawler cameras are robust remotely controlled inspection robots that traverse through a pipe on wheels. They typically have a strong light source to illuminate the inside of the pipe and are connected via a cable to a vehicle on the surface that supplies power and transmits the video back to a vehicle computer for recording. The robot is controlled by an operator on the surface who directs the crawler’s progress through live vision fed back to their computer monitor. They can adjust for speed and direction, and often have the ability to pan, tilt and zoom the camera lens; leading to the term PTZ camera (they are also called tractor cameras in some regions). Crawler cameras are the most common type used for pipe network inspections throughout the world.

Fixed Zoom Cameras

Fixed zoom, or pole cameras, do not need to travel along the pipe to collect video footage. They consist of a fixed high-definition camera head attached to a pole that is lowered from the surface to the base of the pipe at surface entry locations. Using a combination of strong zoom, focus adjustment, and lighting; a video is recorded as the camera zooms in and the field of vision extends through the pipe from chainage zero to the end of pipe or bend. With a combination of optical (20-40x) and digital zoom (10-15x) they provide a fast and robust way to collect a condition overview of a network.

Push Rod Cameras

House connection branches or sewer laterals present unique challenges when collecting condition footage or diagnosing a problem. Their small diameter and frequent bends mean the larger camera hardware is unable to enter and travel through these smaller lines (typically < 150mm diameter). Push rod cameras are designed for tough and tight conditions. Appearing as a coiled cable on a real with a slim camera head, they can be inserted and controlled manually with imagery fed back to a control unit. The use of skids is sometimes employed to keep the camera head and vision steady and centred.

Inspection Rafts

For large pipes that cover long distances, an inspection raft may be the only choice to collect imagery from within a pipe. These are often used for outfall tunnels where they can be sent downstream and caught with a hook or net at location that could be many kilometres further down the pipe. They are usually designed to stay upright and balanced.

Drone Cameras

With rapid advancement in UAV technology, the industry has seen an increase in the use of drones for pipe inspection over the last few years. Drones have some distinct advantages in certain situations, including; large pipes with high flow where a crawler may not be able to enter and raft would traverse along the pipe too quickly, and longer pipe inspections where equipment weight or cable length is prohibitive. It will be interesting to see how this technology develops and if it becomes a more mainstream option for pipe networks.

Manhole / Maintenance Hole Cameras

There are now a variety of dedicated cameras available for collecting photos, videos, and 3D scans of the vertical shaft that leads down to the benching and pipe channel. In the past this has been completed by visual surface or confined space entry inspection, using a regular camera, or with a crawler as it is lowered down to complete the main pipe inspection. Newer camera technology has been specifically designed to collect more detailed information with much higher resolution than ever before.

Jetter Nozzle Cameras

Jetters can be used by operators to clear sediment, obstructions, fats, oils, grease, and roots from pipes. Some hydro jetters on the market include a nozzle camera that can be used to help guide the camera through the pipe, locate specific issues and even steer into lateral pipes. The camera is also able to collect video footage following its cleaning run through the pipe to collect information on the effectiveness of the clean and provide an indication of the condition of the cleaned pipe.

Targeting the Correct Pipe Slope

Why is pipe slope important?

Different ways to measure pipe slope and straightness?

An out of the box solution!

When the pipe doesn’t meet the required slope

Evolution of ideas

About the Author

Learn more about Sewer Network

Increasing the value of wastewater network monitoring

Innovation is the key to delivering ever-increasing performance

Repairs are not always practical or cost effective

Data is key to making informed decisions

Conclusion

Local Sewer History Finds

Keeping an eye out for local sewer history finds

Finding a piece of Sydney’s sewer history

Transporting sewage to Bondi

Could reinforced concrete be trusted?

The rest is history

Still interested in more of the aqueduct’s history? Well, there was some controversy!

Opportunities to improve the UK pipe inspection standard (MSCC5)

Introduction

Is history holding back the future?

How could we look at things differently?

Coding observations

Condition Assessments

Final thoughts

Different Types of Pipe Inspection Cameras

Crawler Cameras

Fixed Zoom Cameras

Push Rod Cameras

Inspection Rafts

Drone Cameras

Manhole / Maintenance Hole Cameras

Jetter Nozzle Cameras

About the Author

Quick Links

CONTACT US

Still interested in more of the aqueduct’s history?
Well, there was some controversy!