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Exfiltrating sewers in water catchment areas (Abschnitt 6.1) cause damage to a higher level of interests protected by standards or law as in regions without water catchments. The care of groundwater must be set unmistakably higher than malfunctions of the sewage operation caused by defects that must be repaired by means of technical measures of the sewer operation. The following regions are kept apart from each other: Catchment area IIIa: The drain … |
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Taking the protection aims into account, the priorities can be changed for good reasons. Examples of this can be:
The up- and downgrading … |
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The priorities list is made up of the downgraded evaluation numbers. Its provides a sequence for the measures to be undertaken in the sequence of the condition classes of the type of sewer, the interests protected by standards or law as well as the evaluation or condition points. |
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In order to be able to check and interpret the evaluation numbers given in the priorities list, the values in the condition evaluation and the up-and downgrading carried out in the reclassification can be read off from the evaluation number (Tabelle 4.7.2.1.6) (Tabelle 4.7.2.1.6). (Table: Structure of the evaluation number in accordance with ATV-M 149 [ATVM149a]) (Table: Allocating the numbers in accordance with ATV-M 149 [ATVM149a]) In Bild 4.7.2.1.6 |
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Nov 22, 2004 With the ATV-M 149 "Zustandsklassifizierung und -bewertung von Entwässerungssystemen außerhalb von Gebäuden" published in April 1999, the Abwassertechnische Vereinigung presents a possible procedure for condition evaluation and classification that contains the execution of the methods presented in Abschnitt 4.7.1 [ATVM149a]. For the damage acquired according to ATV-M 143E Part 2 [ATVM143-2] (Abschnitt 4.6.1), this condition evaluation model makes … |
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Feb 16, 2011 The evaluation of the structural condition is based on the damage description in accordance with ATV-M 143E Part 2 [ATVM143-2] (Abschnitt 4.6.1). The evaluation of the structural condition with reference to the existing condition as well as the actual extent of the damage, is carried out in the KAPRI model by means of a rigid base evaluation and a dynamic factorising. First, a quantitative base point number is allocated to the general type of the … |
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Feb 16, 2011 Besides the evaluation of the structural condition, the actual potential for danger is estimated and quantified for the defined point of damage on the basis of the specific damage to its environment. Hereby, in the evaluation in accordance with the tasks of a sewer, the aspects of:
are taken into account. This is carried out in the form of a query of the master data shown in Tabelle … |
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Feb 16, 2011 The complete condition evaluation is found from the linking of the two separately found results, the evaluation of the structural condition as well as the limiting conditions, in the form of a multiplication. It is shown that damage of the same type and the same extent but with different section-specific limiting conditions with a view to their actual potential for danger are judged and evaluated differently from statistical, ecological and functional … |
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Nov 22, 2004 (Image: Diagram of sewer condition evaluation with KAPRI with reference to [Mölleb] [Image: S&P GmbH]) A classification system that has long been used in practice and that has proven itself is the KAPRI system (abbreviation for KAnalsanierungs-PRIoritäten), a development of the Ingenieurbüro für Kanal-instandhaltung (IfK) in Bochum. It takes the requirements of EN 752-5 [DINEN752-5:1997] mentioned in Abschnitt 4.7.1 fully into account. The basic idea … |
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Nov 22, 2004 At present, the parties who carry the responsibility are in need of a generally valid measure of evaluation for the required condition classification and evaluation, especially when it comes to determining the sequence of rehabilitation with reference to the damage that has occurred and the potentials for danger resulting from them. Besides the Abwassertechnischen Vereinigung (ATV), various other engineering consultancies, sewer inspection companies … |
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The causes of the defects must be based on the results of the hydraulic and environmentally relevant and structural investigations (Abschnitt 4.3) (Abschnitt 4.4) (Abschnitt 4.5). The effects of each cause should be evaluated in order to work out suitable solutions and to determine the priorities of the measures to be undertaken. For this purpose, condition classifications and condition evaluations must be gone through within the scope of the evaluation … |
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According to EN 752-5 [DINEN752-5:1997], after rehabilitation, the nominal condition of a structure, a sewer sector, a section of the sewer, a network region or drain and sewer system must conform at least to the same standards that apply to a new sewer. Naturally, this also applies to the materials and components used [Rothe83]. The loading that is possible and the corresponding characteristics required are given in very general form in Tabelle 5.1 |
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Feb 16, 2011 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].
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Feb 16, 2011
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 … |
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Feb 16, 2011 An important point in the repair of manholes is the replacement of corroded or broken climbing rungs (climbing irons, safety steps or ladders) (Abschnitt 1.8). When installing, the installation instructions must be adhered to. It must be ensured that material, shape and step heights per manhole are the same (see ATV-A 137 [ATVA137]) and that the condition of the manhole wall is such that the exchange is permissible from a statics point of view. The … |
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Feb 16, 2011 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:
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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 … |
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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].
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Nov 22, 2004 Rehabilitation and Maintenance of Drains and Sewers Restoration of Concrete, Reinforced Concrete and Pre-stressed Concrete Sewers 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 … |
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Feb 16, 2011 Rehabilitation and Maintenance of Drains and Sewers Restoration of Concrete, Reinforced Concrete and Pre-stressed Concrete Sewers (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 … |
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Nov 22, 2004 Rehabilitation and Maintenance of Drains and Sewers Restoration of Concrete, Reinforced Concrete and Pre-stressed Concrete Sewers For a durable bond between old concrete and repair grout, and with reference to the repair process, the concrete foundation must possess the following properties [Grube90] :
For most of the measures, a certain degree … |
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Feb 16, 2011 Rehabilitation and Maintenance of Drains and Sewers Restoration of Concrete, Reinforced Concrete and Pre-stressed Concrete Sewers (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 … |
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Measures for the restoration of defective regions in the inside of sewers of concrete, reinforced concrete and pre-stressed concrete have the aim, depending on the selected repair grout, among others of [DAfStBb] :
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Although sewer clinkers in masonry sewers are generally resistant to acids (for exceptions (Abschnitt 2.6.4), the cement-bound grout joints are destroyed with corresponding loading (Abschnitt 2.6.4). If these masonry joints are not filled in with an appropriate grout again (pointing), then the result can be leaks, the falling out of one or more sewer bricks from the walls up to collapse of the arching. In this type of damage in the wetted cross section, … |
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