In recent years, there has been a growth in the development of methods for No-Dig renewal, flushing and CCTV inspection of laterals – all carried out from the main pipe. These methods mean minimum inconvenience to residents, business owners and traffic.

No-Dig methods are also cost effective compared to conventional excavation. The following cured-in-place pipe (CIPP) lining methods cause only a minor reduction of the pipe’s cross section, whereas other methods, such as sliplining of small dimension pipes, can cause an unacceptable reduction of the pipe’s cross section.

One thing it has in common to other methods is that it is not necessary to have access to the pipe system on private property as all the methods can be carried out from existing manholes on public thoroughfare.

Lateral connection collar – hat profiles

Hat profiles are lateral connection collars sealing the connection between the lateral and main pipe. In general, hat profiles are only installed in relined pipes. They can be installed in pipes made of concrete, clay or plastic, but adhesion to the surface of the existing pipe cannot be guaranteed.

Short hat profile from main pipe

The short Aarsleff Hat Profile is a tight lateral connection collar made of acid proof polyester fibre. The length of the short hat profiles used for Copenhagen Energy resulted in the passing of the first connection on the lateral.

A short hat profile consists of a rim of collar and an endless extension of the collar. The product is tailor-made for specific projects on the site, where it is also impregnated with resin.

For installation, a short hat profile is fitted to a tool and pulled forward to the lateral in question while monitored by a CCTV camera. When the tool is in position, the rim of collar is pressed into place and the extension of collar is pushed into the lateral. Subsequently, the hat profile is cured and the tool is retracted.

As the lateral is not renewed, this method is used for providing a tight transition between the main pipe and the lateral. The length of a short hat profile is at least 30 cm and past the first joint of the lateral.

Long hat profile from main pipe into lateral

The hat profile is installed the same way as the short hat profile, the only difference is that the lateral is relined all the way to the property boundary, the manhole or the water trap of a road shaft.

Long hat profiles can be made in lengths of up to 17 m.

CIPP lining of lateral

CIPP lining of laterals can be made both from the main pipe and from manholes. The pipe is made with a liner of acid-proof polyester fibre impregnated with resin.

CIPP lining of lateral from main pipe into lateral

In principle, CIPP lining of a lateral from the main pipe into the lateral consists of a long hat profile without a rim of collar installed in the main pipe. If this solution is chosen, no tight transition between the main pipe and the lateral is provided. CIPP lining can be made all the way to the property boundary or water trap of the road shaft. It can be made in lengths of up to 20 m.

CIPP lining of lateral from boundary manhole towards main pipe

CIPP lining of laterals from the boundary manhole towards the main pipe is also made with a liner of acid-proof polyester fibre impregnated with resin.

From the manhole, the soft liner is inverted into the defect pipe by means of air and the end of the liner is open.

Then a calibration tube is inserted and the tube’s end is sealed, the material does not combine chemically with the resin-impregnated CIPP lining. Therefore, the lining is cured and the calibration tube is retracted.

If too long, the protruding end should be cut off in the main pipe. Endless CIPP lining from manholes can be made in lengths of up to 25 m.

CIPP lining of lateral from roadway inlet with water trap towards main pipe

This type of CIPP lining is carried out in the same way as CIPP lining from a manhole.

Spot repair or plugging of lateral

Laterals no longer in use may be closed by means of spot repair or plugging depending on the condition of the lateral or the main pipe.

Spot repair

Spot repair consists of a short relining, customised for the actual job on the work site. It is made of acid-proof polyester fibre impregnated with resin.

The impregnated CIPP lining is mounted on a tailor-made tool which is pulled forward to the place in question while being monitored by a CCTV camera. When the tool is in position, the pressure in the tool is increased and the spot repairs are pushed into place. The spot repair is then cured, and the tool is retracted.

Plugging of lateral at main pipe with Lock Pipe Grout

Lock Pipe Grout is the only product for plugging of laterals approved for use in the water and sewerage system by Danish authorities.

Installation of Lock Pipe Grout from the main pipe provides an advantage against conventional installation methods, where installation takes place by means of an excavation pit, a duckfoot bend or similar.

An advantage of Lock Pipe Grout over spot repair is it does not affect the hydraulics of the main pipe. Through the manhole and the main pipe, the Lock Pipe Grout is pulled forward to the lateral in question.

The Lock Pipe Grout is inserted in the lateral and filled with rapid-hardening concrete. After hardening, the equipment is retracted.

Development of equipment and technological innovations

The industry is forced to develop new methods and be innovative within a multiannual framework agreement where the client continuously makes new demands .

For example, the development of CIPP lining from road shaft and the installation of Lock Pipe Grout are a result of the client’s demands.

The challenge that remains is the measuring up of laterals and opening of laterals through laterals.