This lecture is part of the series "Trenchless 101" and serves to provide an overview of trenchless repair methods for gas, water and wastewater pipelines.

(Image: Top hat sleeve for the recreation of the branch connection)

The restoration of the branch connections is carried out analogously to Abschnitt 5.3.2.2.1 and Abschnitt 5.3.2.4.1 by the open cut or trenchless methods.

In the case under consideration, the trenchless method is available for sewers from DN 200 and laterals ≥ DN 100 with the utilisation, for instance, of a special top hat sleeve developed for the TROLINING^® system (Abschnitt 5.2.3.2.3). …

(Image: Creation of the core bore by means of a core drilling machine rectangular and central to the axis of the sewer [FI-DS])

When connecting a lateral which has been laid in a line trench or by the trenchless method of construction by employing the open-cut method the section concerned of the sewer has to be excavated and secured by observing EN 1610 [DINEN1610:1997] [DINEN1610-1:1997], ATV-DVWKA 139E [ATVA139a] and DIN 4124 [DIN4124:2002].

Since …

In this rehabilitation measure, neither the manhole tops, nor the surrounding covering and carrier layers, are removed. There follows only the lifting or lowering of the frame that has previously been loosened with the aid of special mechanical or hydraulic machines (Bild 5.2.1.1.1) (Bild 5.2.1.1.1) (Bild 5.2.1.1.1) (Bild 5.2.1.1.1) [WPCFFD6] [NASSCO85a] [WPCF85].

The height levelling of manhole tops with removal is always carried out when the surrounding cover layer is also damaged by the formation of cracks, deformation, etc. (Bild 5.2.1.1).

As a rule, the repair is carried out by the removal of the surrounding covering and carrier layers as well as the damaged manhole top including possibly the supporting ring, if there is one, then the installing it again at the desired level.

Subsequently, the surrounding …

Because the structures of drain and sewer systems, and especially the manholes, are mostly constructed of concrete, reinforced concrete or brickwork, the following will deal exclusively with the local restoration of missing portions of these materials.

Such defective areas that can occur in the manhole walls, joints, connection regions, as well as in the benching and the channels, are, for instance:

• Partial surface corrosion;
• Ejection of the cover …

An important share of the repairs to manholes is the regulating and exchange of manhole tops because today, as compared to earlier, much greater demands are made on the evenness of the traffic lane and these are subject to higher loads due to the heavier traffic …

Repair measures to sewers from the outside involve especially the replacement of single or several damaged pipes.

In this case, after placing the section of the sewer out of action, the defective pipe region is exposed using the open cut method (Bild 5.2.1.2), a closer pipe piece with smooth ends is inserted and the new pipe joint is remade with the aid of sleeve joints (Bild 5.2.1.2) (Bild 5.2.1.2) [FI-Naylo] [FI-Stein93].

Concrete surfaces that are to be the foundation for a repair measure must always consist of undamaged concrete, i.e. they must be free from dirt, old paints that cannot carry loads, floury fine grout layers and all other substances that can reduce a bonding effects (e.g. damaging salts such as sulphates, nitrates).

The concrete foundation must be prepared such that a tight and durable bond can be achieved between the repair grout to be applied and …

(Image: Corrosion protection sealing of the de-rusted reinforcement [BDZ89])

The required preparation of reinforcement rods depends on their condition, on the extent of the corrosion and the type of repair measures. For limited repairs of concrete spalling due to corroding reinforcement, the recommended method is conservation by means of anti-corrosion paints (Bild 5.2.1.3.2) in accordance with the rules for steel construction. An anti-corrosion paint …

(Image: Applying the repair grout by hand [BDZ89])

The application of the repair grout (Bild 5.2.1.3.4) must be carried out before the bonding bridge is fully hardened (working "fresh on fresh"), otherwise there is the danger that the bonding bridge becomes a separating layer.

When preparing and applying, as well as during the finishing process of the repair grout, the preparation instructions of the manufacturer must be carried out. Detailed information …