managing expenses

How are sewer pipes inspected? 

How are sewer pipes inspected?

What is involved in a pipe inspection?

Most of the time required to undertake the inspection is dedicated to finding the access point and securing access. This means finding the right maintenance hole on either the upstream side of the pipe and the downstream side of the pipe. The surrounding areas near the access point must also be made safe and secure, as sometimes they are in roadway, foot paths or private property. Establishing the site is an important part of the inspection process so that there is no risk to the public and the workers involved in the inspection. Once the access point is located and the secured,then an inspection can begin.

An operator will lower the camera crawler into the pipe and remotely drive the camera along the length of the pipe, stopping to make notes of any faults or defects that they might find inside the pipe. They will continue this until they get to the end of the pipe. Once they get to the end, they will pull the camera back (the inspection cameras are usually tethered by a power and data cable) and return to the access point for retrieval.

Another aspect of a pipe inspection that takes time is the actual coding of the defects in the pipe. When the camera is inside the pipe, the trained operator must watch the video feed and identify and classify the type and location of the defect along the pipe.  

Sewer pipe inspection

What information does an inspection record?

Operators are trained to undertake this classification and quantification in alignment with their regional coding guidelines. These guidelines are used widely, and help to ensure consistency in understanding across organisations, stakeholders, and professionals. 

How can we increase the speed of inspections?

Some ways to increase the speed of an inspection is by implementing new hardware, new software, more effective training methods and materials, or by applying an improved process to inspections. Given that most of the inspection is concerned with locating the right asset and establishing the site, methods that make those processes more efficient would also have an impact on the turnaround of sewer pipe inspections. 

About the Author

Amanda Siqueira is an Australian civil and environmental engineer who has worked in design, construction and remediation of drainage and sewer pipes in Australia, New Zealand and the UK. She has passion for all things pipes and is also one of the Co-founders of VAPAR.

Amanda Siqueira, CEO & Co-Founder VAPAR
Experience the future of pipe condition assessments.

managing expenses

Why am I being charged for sewer? 

Why am I being charged for sewer?

Why am I being charged for sewer?

If your water authority is charging you for the capture, treatment and delivery of potable drinking water, then there is a high chance they are also charging you for the capture, treatment and discharge of wastewater. There are a number of processes that take place for water authorities to deliver these essential services to rate payers. If this service is not delivered well, there is an increase in risk to public health and the environment. 

managing expenses

What does the money go towards?

The primary functions of wastewater services is to collect, treat and discharge wastewater. The objective of any wastewater system is to do this in the most efficient manner that meets the public health and environmental goals of the community. This can be really challenging, as there are several technical and non-technical outcomes that need to be achieved. But at the heart of it, the system can be broken down into: 

  1. Collection systems- these are generally the pipes, manholes, trunk sewers, pumping stations etc.
  2. Storage systems- these are generally septic tanks, temporary storage tanks, etc. 
  3. Treatment/discharge systems- these are generally wastewater treatment/recycling facilities and discharge structures. 

Each of the above sub-systems needs to perform well in order to meet the public health and environmental goals of the community. There is an expense to keep these systems performing 24/7, and that is what the sewer charges go towards. 

wastewater management

How do the charges get applied?

Each water authority charges differently depending on the regulation and legislation in the region. For most water authorities, the charges are split up into fixed charges and variable charges, and the way they charge their customers often differs by customer type. Fixed charges are charges that customer pay on a regular basis (e.g. quarterly) for the fact that there is a connection into the public sewer system. Variable charges are charges based on a usage metric (e.g. per kilolitre or per hundred cubic feet). From what I have seen, most variable usage charges are applied to commercial and industrial customers, and less likely to apply to residential customers. The usage of residential customers is usually covered in the fixed charge. Because commercial and industrial wastewater discharge has a higher load of contaminants, there is a greater level of treatment complexity required that the water authorities have to account for, therefore levying an additional usage charge to cover the associated costs. 

About the Author

Amanda Siqueira is an Australian civil and environmental engineer who has worked in design, construction and remediation of drainage and sewer pipes in Australia, New Zealand and the UK. She has passion for all things pipes and is also one of the Co-founders of VAPAR.

Amanda Siqueira, CEO & Co-Founder VAPAR
Experience the future of pipe condition assessments.

Sewer inspection using CCTV

How frequently are sewer pipes inspected? 

How frequently are sewer pipes inspected?

How frequently are sewer pipes inspected?

There are over 11 billion meters (36 billion feet) of wastewater pipes that have been installed underground around the world, and this number continues to grow as the number of dwellings increases to support a growing population. A lot of these wastewater pipes have been installed in the last 40-70 years, and the pipes themselves come in a variety of materials and diameters.  

large sewer

The design life of a wastewater pipe?

Engineers design pipes for a certain design life, meaning the duration of time that the asset is expected to be in use before it deteriorates to the point of failure. In the case of underground wastewater pipes the design life is generally between 100 years and 150 years. During the pipes design life, it is prudent to check the pipes regularly to make sure that they are not blocked or broken.

Sewer inspection using CCTV

How frequently are these wastewater pipe inspections carried out?

This process is called an inspection and is usually carried out by trained professional using a small CCTV camera that is remotely driven through the pipe, capturing video footage of the internal condition of the pipe as it goes. The best practice is to undertake these inspections at a frequency of around once every 10 years, equivalent to inspecting 10% of the network every year. This frequency means that it would take the relevant water authority 10 years to get around to the same pipe if it were to continuously inspect their pipe network. Water authorities are inspecting their network continuously, but not at the ‘best practice’ frequency of once every 10 years. The frequency at which pipes are inspected differs based on the water authorities’ budgets and the risk of that asset’s failure to the community and environment. In some areas and countries, it is common for pipes to be assessed at a much lower frequency i.e. Inspected at less than 10% of the network every year. In the United States, almost 7% (source: https://www3.epa.gov/npdes/pubs/sewcl.pdf) of the network is inspected each year, but other countries like the United Kingdom and Australia (based on anecdotal industry experience) is less than 5%.  

How frequently are these wastewater pipe inspections carried out?

One way to increase the frequency of wastewater pipe inspections is to decrease the cost of the inspection itself. To decrease the cost of an inspection there must be an associated increase in productivity. This can come from new hardware, software, more effective training methods and materials, or by applying an improved process to inspections. Another way to increase the frequency of inspections is to increase the budget associated with carrying out inspections, however, this is a very challenging method since most water authorities are budget constrained and therefore have a limited ability to apply this method. 

About the Author

Amanda Siqueira is an Australian civil and environmental engineer who has worked in design, construction and remediation of drainage and sewer pipes in Australia, New Zealand and the UK. She has passion for all things pipes and is also one of the Co-founders of VAPAR.

Amanda Siqueira, CEO & Co-Founder VAPAR
Experience the future of pipe condition assessments.

Underground sewer

What material types are used for sewer pipes?

What material types are used for sewer pipes?

What are sewer pipes and where do they go?

Wastewater pipes are pipes that carry wastewater from a property to the source of disposal. The source of disposal may be different depending on where the property is located relative to major urban centres, but for most people the source of disposal is a bigger ‘trunk main’ pipe that eventually leads to a sewage treatment plant or ocean outfall. Because these pipes manage wastewater from every property, they are under the ground almost everywhere people live. There is an estimated 11 billion metres (36 billion feet) of wastewater pipes in the world. That’s a lot of pipe! 

Underground sewer

What are sewer pipes made of?

With so much pipe being put in the ground, what are they actually made of? Well, it depends. Depending on the use of the pipe, and the design of the installation, different materials can be considered. For example, pipes that are used for collecting wastewater from residential dwellings can be small diameter and the pipe can be made from a variety of flexible plastics. However, pipes that are large diameter trunk mains are more likely made of stronger materials such as concrete or HDPE. 

PVC pipes

What are the other different sewer pipe materials?

If you’re looking for some great information and data to answer this question, the US EPA has a useful fact sheet on the common pipe construction and materials here. There is also a data breakdown of pipe materials in sewer pipes in a previous post that we did here. From the dataset that we analysed, the most common pipe material for sewer pipes was vitrified clay, followed by concrete, then by flexible plastics. Vitrified clay was popular because it was a cost-effective solution. More recently, flexible plastics are more common in new installations, so over time we will likely see the percentage of sewers in the ground that are plastic increase. 

About the Author

Amanda Siqueira is an Australian civil and environmental engineer who has worked in design, construction and remediation of drainage and sewer pipes in Australia, New Zealand and the UK. She has passion for all things pipes and is also one of the Co-founders of VAPAR.

Amanda Siqueira, CEO & Co-Founder VAPAR
Experience the future of pipe condition assessments.

Trunk sewer

Trunk sewers – changes in inspection methods

Trunk sewers – changes in inspection methods

What is a trunk sewer?

A trunk sewer is usually a large diameter pipe that wastewater from smaller diameter sewer pipes connect to downstream. These carry the wastewater from upstream catchments and carry the flow downstream to a discharge point. Depending on the size of the catchment and population upstream, the trunk sewers can be quite large in diameter, most of them are large enough for people to walk through. 

Trunk sewer

Why are sewer trunk mains needed?

A trunk sewer is the most cost-effective way to transport large amounts of wastewater from upstream populations to a downstream discharge point. If we didn’t have trunk sewers we would need to take wastewater from every property all the way from the most upstream point in the network through to the discharge point, which is cost prohibitive. Due to the importance of these large pipes to urban centres, it is imperative that they are in good condition and maintained and inspected regularly.

Due to their sizer and flow capacity, trunk sewers often have a higher consequence of failure compared to the smaller upstream collection network. If a trunk sewer was to fail due to a blockage or a collapse the results can be extremely expensive to repair, damaging to the local environment, and disrupt the use and access to surrounding public and private infrastructure.  

How are trunk sewers inspected?

Traditionally, because of large diameter nature of trunk sewers, trained and certified professionals should be used to carry out inspections, and they do these inspections by walking through the trunk sewer. These highly skilled and trained professionals not only carry out the condition inspection of the pipe, but also complete this in a safe manner. It is normal for these inspections to be carried out while the sewage is still flowing in the pipe which means the inspection should only be carried out in low flow times of the day (i.e., not during peak usage or after recent rainfall) and when the section of pipe to be inspected is well ventilated and monitored.

The airspace in the truck mains is considered to be a hazardous environment due to the H2S gas generated from raw sewage. Additionally, the pipes are ‘confined’ in nature (i.e., There is no free flow movement of air). For that reason, forced ventilation equipment is sometimes used and people inspecting the pipes wear gas masks and gas monitors for the duration of the inspection.  

What are the changes in the trunk sewer inspection technology?

There is new technology available on the market that means that people don’t need to enter these hazardous and confined environments. This new technology improves the safety outcomes for the inspection process dramatically as they can reduce or eliminate the physical entry of personnel. The devices used can be tethered or untethered, meaning that the inspection device may or may not be connected to a particular location. An example of this technology is floatable cameras that undertake 3D imaging of the pipe as they flow through. There are also vendors that provide wheeled robotic inspections, whilst others provide drone hardware that fly through the pipe. 

About the Author

Amanda Siqueira is an Australian civil and environmental engineer who has worked in design, construction and remediation of drainage and sewer pipes in Australia, New Zealand and the UK. She has passion for all things pipes and is also one of the Co-founders of VAPAR.

Amanda Siqueira, CEO & Co-Founder VAPAR
Experience the future of pipe condition assessments.

sewer blowback

Sewer Blowbacks –Releasing the pressure!

Sewer Blowbacks – Releasing the pressure!

What is a Sewer Blowback?

A sewer blowback is when a combination of air/water/wastewater is ejected from a household wastewater fixture, such as a basin, floor drain, gully trap, and, most commonly a toilet.

This can occur when routine or reactive maintenance is being carried out on the utility’s sewer network with high-pressure water jetting equipment. Water jetters are used to clear roots, debris and blockages in the sewer system and ensure flow occurs uninhibited. 

Blowbacks occur due to difference in pressure in both the main sewer line and the attached house plumbing. When jetting equipment is in use, water is forced into the sewer main under high pressure, this requires the displacement of a similar volume of air. The space behind the jetter is an area of high pressure, while there can be a negative pressure zone in front of the jetter nozzle. In most cases this air is forced along the sewer main or out private property vents. However, if there is insufficient ventilation, or a blockage in a house vent, this pressure will move to take the path of least resistance. This can result in pipe odors rising through floor drains, and if there is enough positive pressure the water seal in the toilet bed can be blown with force out of the fixture. 

The inverse of a ‘blowback’ can occur where negative pressure occurs in property plumbing, and the water seal in fitting bends can be sucked out, resulting in an atmospheric opening to the sewer causing the odour from the sewer to flow through the fixture into the room that it is located. In these cases, it can be rectified by adding additional water to the water seal 

sewer blowback process

Why do sewer blowbacks occur?

There are two factors that can be attributed to a sewer blowback within the property drain itself. 

A drainage vent can become blocked or restricted over time which can increase the likelihood of a sewer blowback. 

Blockages within the sewer main can also cause water to build up on the upstream side of them; when the jetter nozzle goes past the property connection the water can be forced up the connection pressurizing the property drain unless it has somewhere to go. 

sewer blowback

How can we prevent or minimise sewer blowbacks happening?

 There are several factors that contribute to sewer blowbacks that happen during the cleaning of the sewer main, some can be minimised/mitigated, and others cannot. 

  1.  Communicating to property owners that sewer main cleaning is scheduled, and it is recommended that they keep toilet lids closed. 
  2. Opening the upstream manhole to allow additional flow into the main being cleaned. 
  3. Using lower pressure and/or flow from the jetting truck.

    Most blowbacks consist of only the contents of the water volume within the trap/water seal and is usually clean water that is replaced on a regular basis by flushing the toilet and running a tap. Some utilities will keep a blowback register of historical occurrences. It is recommended to contact them if this happens to help inform future maintenance programs and minimise the potential of it happening again.  

     

About the author Anthony Woodhouse
lateral sewer pipes

Thinking laterally – Can lateral inspections supplement your inspection program?

Thinking laterally – Can lateral inspections supplement your inspection program?

The majority of any pipe network is made up of the smaller diameter lateral connecting pipe lengths (relative to mainline lengths), so it’s no surprise that lateral inspections are becoming more and more popular.

Let’s take a look at what you need to know about lateral inspections.

lateral sewer pipes

What are lateral inspections?

Lateral inspections are inspections that survey the connecting pipe to the main line. The inspection can either be done from an access point upstream of the connection back down to the mainline or from the mainline up through the lateral connection to a connection point or boundary point upstream.

Depending on where in the world you are, these connecting pipes to the main line are sometimes called house branch connections, junctions or taps. Similarly, there are also varying ways to undertake a lateral inspection or coding defects associated with the lateral. Some countries include lateral condition coding with mainline condition coding, whilst others treat the lateral condition coding separately.

Why are lateral inspections required?

Water authorities will do lateral inspections for several reasons. Most organisations undertake lateral inspections in their network because they own the lateral and are therefore required to maintain all or part of the lateral length. There are some organisations that proactively undertake lateral inspections to investigate unknown connectivity of the network.

When should I do a lateral inspection?

Funding an inspection program can be challenging sometimes. So, adding lateral inspections to your inspection program might sound like an extra burden. Let’s look at some of the reasons water authorities choose lateral inspections for their inspection program that make the investment worth it:

  1. Investigating reported customer issues – if a customer reports an issue and no problem can be identified with the mainline pipe.
  2. Investigating network connectivity – if there are suspected illegal connections in the lateral network, or if th
  3. As a workaround for upstream access restrictions

All of the above challenges cost the water authority’s money if left unresolved, which makes the business case for lateral inspections much easier. The magnitude to which this impacts your organisation will drive a cost-benefit ratio that makes sense for your organisation’s circumstances.

lateral inspection launch

Minicam lateral launch

How can I get a lateral inspections done?

Depending on the reason for the inspection, and that site access conditions, lateral inspections are usually undertaken in one of two ways.

  1. Starting from the mainline – The first, is from the mainline using specialist inspection camera technology. This involves a type of camera that has ‘lateral launch’ functionality, which basically means a camera can be ‘launched’ up the lateral up to a length of 150 ft or 45.72 meters.  There are restrictions on the use of these types of cameras, such as lateral and camera angles. This type of inspection can help with access issues, and investigations of network connectivity.
  2. Starting from an upstream point in the lateral – The second way to do an inspection of the lateral starting from an upstream point in the lateral down towards the mainline. Its possible to do this type of inspection with a standard CCTV inspection camera (either crawler or pushrod). This type of inspection can help with investigations of customer issues.

Conclusion

The increased demand for lateral inspections can be attributed to a number of things, not least of which the availability of the technology, and increased customer reporting capability and more. Either way, these inspection methods are a great way to supplement your upcoming inspection programs where the needs arise.

About the author