R&M Utility and Civil Engineering Services are committed to finding high-quality and economical solutions for their clients. As a sewerage contractor in the South West, R&M are continually researching repair and rehabilitation techniques; repeatedly demonstrating the advantages of trenchless technology over traditional excavation dependent repairs.
There are 4 main categories of sewer repair utilising “no dig” technology: Patch Lining, Cali Patching, Hot Cure Lining and Ambient Cure Lining. The horizons of trenchless technology continue to expand, with contemporary developments such as the Lateral Inflow Repair Robot. Whilst not suitable to all repair scenarios, trenchless techniques offer significant budgetary, scheduling, health & safety, structural and environmental benefits, to local ecosystems and human surroundings.
The Principles of Pipe Lining
The material used for a patch lining repair is impregnated with an epoxy resin and then wrapped around a pipe packer for insertion into the sewer, via a manhole or similar access point, up to the point of the defect. It typically takes an hour for the resin to cure, depending on conditions, after which the packer is removed, and the pipe is defect free. R&M have the capability to deliver all of the following Lining techniques:
• Patch Liners can cover any defect within 100mm up to 750mm diameter sewer lines but are limited from lengths of 1 metre up to 3.7 metres.
• Cali Patches are used to repair larger scale, major defects and can be applied to pipe diameters of 100mm and upwards.
• Hot Cure Liners are used for large diameter sewers (150mm-900mm) and can line continuously for over 300 metres.
• Ambient Cure Liners apply to smaller sewers (100mm to 150mm) and are limited to 50 metres in length.
Case Study 1
– Hot Cure & Cali Patch Lining
To circumvent a 4.2 metre deep excavation to repair 3 sections of 225mm VC sewer pipework, totalling 41 metres running beneath residential gardens, R&M used a mixture of Cali Patches and Hot Cure Lining. Before liner installation the crew meticulously extracted broken pieces of pipework from the sewer, a painstaking 8-hour operation using a CCTV camera and push rods. A full-length liner using a Hot Cure was installed in one section to increase structural strength whilst remedying multiple defects. This was particularly important because the pipework ran under an electrical substation; and if a dig was carried out, the rear of the customer’s house would have needed removing. The use of trenchless technology enabled repairs to be carried out cost-effectively in optimal safety conditions while safeguarding customer property and minimising disruption by avoiding digging in gardens – which can often be a cause for a customer complaint.
Case Study 2
– Lateral Inflow Repair Robot
R&M demonstrated their innovative streak when recognising an opportunity to bring the Hermes Lateral Inflow Repair Robot from Germany to the UK. A series of degraded lateral connections discharged into a sewer main which spanned the 1km length of a narrow one-way residential street. In this environment the deep excavations needed to replace pipework would have produced an unacceptable level of disruption caused by road closures, with potential to generate community complaints. The robot made it possible to carry out trenchless repairs to the laterals without disturbing the soil. For each lateral, the robot was lowered into the sewer main from the back of a van via a manhole and winched into place on wheels. On reaching the point of repair the robot inflated an appendage up to 50cm high to create a temporary seal inside the lateral. Non-toxic liquid concrete mortar pumped from the van was then injected inside the lateral to fill-up a honeycomb lattice of holes constituting the void surrounding the lateral, preventing further infiltration of sea water from a nearby estuary. With a 30 to 45-minute curing time, a saddle was created to envelop the defective lateral and create a completely watertight seal, much superior to the original integrity of the lateral connections. By using advanced trenchless technology R&M mitigated the negative environmental and community impact that a series of digs would have had. Spend on the client’s budget was reduced and stakeholder interests protected. Importantly R&M showed skill in matching the technology with an appropriate environment – they capitalised on an opportunity to the mutual benefit of the company, the client and their stakeholders.