A Deep Dive Into Trenchless Technology for the Maintenance of Utility Networks
Regular inspection for maintenance and repairs of underground utility networks, especially water and gas pipes and sewage systems, is a necessary and safe practice. However, this frequently causes disruptions for both drivers and pedestrians.
We’ve all been unfortunate enough to get stuck in traffic jams or waiting at temporary traffic lights for a long while. These disruptions often come about because of those underground works that require roads to be shut down.
Trenchless technology is the ideal solution for this, creating a much more non-disruptive and time-efficient method for these necessary works to take place.
Let’s take a deep dive into this no-dig method for maintaining underground utility networks, which techniques and tools can be used, and how Hy-Ram supports this procedure.
What is trenchless technology?
Trenchless technology is a series of underground construction techniques that are also referred to as no-dig, as they involve minimal open excavation and surface disruption. These techniques are used for maintaining, rehabilitating, and repairing underground utilities, such as gas and water pipes.
Benefits of trenchless pipe repair
This method of pipeline repair and maintenance boasts many great advantages, making it a widely used process.
Perhaps its most important and widely recognised benefit is its minimal disruption to the surrounding environment. Trenchless technology is an extremely quick and efficient method of repairing and maintaining pipelines which results in reduced downtime, leading to improved cost efficiency on the entire project.
This is particularly useful in urban and busy areas, like large cities, where road disruptions caused by underground works would have many negative impacts on traffic and communities.
As this procedure requires minimal excavation, it also means there is little impact on the surface, helping to preserve landscapes and minimise soil displacement. This further results in fewer emissions.
With such minimal excavation, this greatly enhances crew safety from not being exposed to open trenches.
Trenchless technology, with its many benefits, is used for critical utility networks, serving both service pipes and mains pipelines. Both of these applications utilise different techniques and equipment.
Techniques for service pipes
The no-dig method is used when replacing or initially installing smaller service pipes. The maintenance and replacement of these pipes is an essential task as these service lines connect main water or gas supplies to a building.
Two trenchless techniques and tools can be used to carry out this important work for service pipes.
1. Impact moling
Impact moling is the most commonly used trenchless method for service pipes work.
First, two small entry and exit pits are required for where the service pipe should run through. Pneumatically driven soil displacement moles are then used to create a bore in the ground and displace the soil rather than excavating it. The borehole can then be used for pipes to be pulled through.
This simple technique is quick to both set up and operate, and can be completed in a single day. The speed helps to minimise disruption and lower total project costs, as fewer crew members are required and less time is spent compared to traditional excavation.
At Hy-Ram, we supply a complete range of mole sizes to accommodate many service line projects within utility networks.
2. Towing heads
While impact moling creates the critical pathway for pipes to be pulled through, towing heads are required to pull the new pipe through safely, and ensure that debris and contamination doesn’t enter the pipeline.
Pipelines used for potable water are still treated and chlorinated fully, prior to being put into service. Chlorus tablets can be used for this treatment, with correct procedures, in line with the asset owners regulations.
This method involves inserting the towing heads onto the end of the new pipeline where an eyebolt is then turned to expand the internal grip, securing the tool onto the pipe end. Once this grip is adequately tightened, the pipe can be safely and efficiently pulled through the borehole. Depending on the application, pipes can be pulled by hand, or by a winch. An alternative option is using an excavator mounted pipe pusher, which is believed to have some advantages.
Using towing heads is a reliable ancillary product in the installation of utility pipes as it offers efficiency without risking damage to the pipes. These tools are also reusable and versatile, making them suitable for many utility network projects and pipe diameters.
Techniques for mains pipelines
Mains pipelines are a critical part of utility networks, distributing resources underground over long distances to supply water and gas to neighbourhoods. These pipes are often larger in diameter and length than service pipes as they carry large quantities of utilities to be filtered through to service pipes.
As such a crucial aspect of the utility system, it’s essential for these pipelines to be frequently inspected and maintained, and require different trenchless techniques.
1. Slip lining
One of the oldest and most common trenchless technologies, slip lining is a simple technique used to replace or rehabilitate old or damaged water and gas mains pipes.
The process involves pulling or pushing a new, slightly smaller diameter pipe (often polyethylene) into the full length of the existing pipe. Towing heads may be used for this technique, too.
The host pipe should ideally be relatively straight to allow the new pipe to easily sit inside without needing to accommodate for any tight bends. Segmental or continuous slip lining can be used depending on the utility’s requirements.
Slip lining restores structural integrity and flow capacity for the pipeline, as well as being a cost-effective, quick, and simple installation method. Typically the carrier/host pipeline is then cut/cracked out in areas or sections, where services need to be installed using an electrofusion top tee fitting, normally. Pipe crackers and bosher bars are popular tools for completing this aspect of the job.
Other pipe cleaning products are commonly used in this type of operation, including Christmas tree drag scrapers, wire brush pigs and plungers.
2. Pipe jointing
For thermoplastic PE pipes that need to be permanently joined together to form part of the mains pipeline, butt fusion and electrofusion welding techniques are commonly used. 
They are robust, reliable trenchless methods that use heat to fuse pipes together.
Our WeldMaster butt fusion machines are used to align the pipes, and heat the two pipe ends until they are malleable and can be pressed together to create a new pipe joint that is secure and precise. All carefully controlled by our software and hardware, to meet the strict standards of the water and gas sector of the UK and many other countries globally. The UK relevant standards are: GIS-PL2-3 and WIS-4-32-08.
Electrofusion is alternatively used out of preference in certain scenarios including smaller/service pipelines, schemes with lots of take-offs or bends/tees, or where it is deemed to be more cost effective. Our range of electrofusion equipment is used to support the correct installation process, in line with UK and globally recognized standards. The UK relevant standards are: GIS-PL2-5 and WIS-4-32-08.
Trenchless technique preparation
For any trenchless method, it’s important to adequately prepare to ensure a smooth, no-dig process without any error or setback.
• Site survey: before any underground work is completed, a thorough survey is needed to draw up a suitable plan of all other existing utilities to ensure the works doesn’t cause any unnecessary downtime, disruption or safety issues. Typical products used in surveying include Cable Avoidance Tools or gCAT4+ and Genny 4.
• Pits excavation: for impact moling, slip lining, and pipe jointing, small access pits at the entrance and exit points are required. These pits are used to deploy equipment and complete the final joints.
• Cleaning the pipe surface: for pipe jointing, it’s important to make sure the pipe surface is free of dirt or contamination to ensure a secure weld. Pipe scraping is a vital procedure for electrofusion welding.
Traditional vs trenchless methods
Choosing between traditional or trenchless methods for pipeline repair depends on the scale and complexity of the pipeline and project.
Traditional pipe repair methods involve digging an open trench for full excavation of the entire pipeline. This technique is a stark contrast to trenchless technology in many ways.
Open trench excavation requires intense labour costs, heavy machinery, and significant time costs as it requires much more soil displacement, or even removal of roads and pavements in urban areas to access the pipeline. This also increases project costs due to the complex reinstatement fees to repair the landscape. Public disruption with higher traffic congestion and road closures are also a given for this method.
In comparison, we know that trenchless methods combat all of these aspects, offering a much more efficient solution to these issues. Trenchless techniques are used to preserve infrastructures, minimise environmental and public impacts, and save on spending.
While trenchless methods are becoming the preferred approach for pipeline maintenance and rehabilitation because of these advantages, traditional open excavation may sometimes be the only viable option. This is typically the case when:
• The existing pipeline is extremely damaged or even collapsed
• The pipe is too deep or large for trenchless techniques
• There are too many other utilities in place
Ultimately, the choice of which approach to go for depends on the full site conditions and the required project outcomes. For the replacement or rehabilitation in utility networks, the speed and efficiency of trenchless technology typically offers the best value.
Driver for change: trenchless technology in action
Trenchless methods are becoming more commonly used in many utility network projects thanks to their wealth of benefits. Due to their speed, ease of use, cost efficiency, and perceived safety advantages, trenchless tools and techniques were used in a large-scale scheme set up by Severn Trent to replace service pipes in Coventry.
In July 2020, the UK government, and the UK water industry regulator OFWAT set out new regulations for water companies 
to help with the country’s green economic recovery. In response, Severn Trent invested £566 million into their Green Recovery programme, with one of its schemes being set up to upgrade service pipes from lead to industry-standard polyethylene.
Installing lead pipes, especially water service pipes, has been illegal since 1970, due to their extensive health risks over long-term consumption. Homes built before this time are likely to still have lead pipes.
The Supply Pipe Replacement Scheme’s mission was to upgrade 25,000 lead pipes across Coventry to the new industry-standard pipelines for free. This saved the customer between £1000 and £3000 and protected them for years to come. The scheme ran from May 2022 to March 2025.
At Hy-Ram, we specialise in the manufacture and hire of industry-leading equipment for the utilities sector. Some of our long-standing customers – Brays Pipelines, OnSite, and Sapphire Utility Solutions – have been using our equipment in their everyday operations for years. For example, their involvement in the Severn Trent Supply Pipe Replacement project saw them utilising our trenchless equipment.
Our impact mole tools, used by Brays Pipelines especially, would have served a huge role in this scheme, with the very nature of this trenchless technique saving a significant amount of time and costs throughout the project.
For such a large-scale, essential project taking place over just less than three years, time efficiency, reduced downtime, and enhanced crew safety would have been vital. Thankfully, with the help of our trenchless equipment to support these methods, these goals were achieved.