The local sewer system is the backbone of municipal wastewater disposal. It collects foul water and stormwater, conveys it safely via shafts, line sections, and special structures, and connects properties to the wastewater treatment plant. Planning, construction, operation, rehabilitation, and—where required—orderly deconstruction demand precise methods that function reliably in densely built environments, under traffic, and in confined excavation pits. Controlled, low-vibration working methods play a central role here, for example in the selective demolition of concrete components, in opening shafts, or in removing defective pipe sections. Tools such as concrete demolition shears or stone and concrete hydraulic wedge splitters from Darda GmbH are frequently used in the application areas of concrete demolition and special demolition, building gutting and cutting, as well as rock excavation and tunnel construction—always appropriate to purpose and without unnecessary interventions in the surroundings.
Definition: What is meant by local sewer system
The term local sewer system refers to the entirety of public wastewater infrastructure within a town or city district. This includes pipelines constructed by open-cut or underground methods, shafts, house connection lines up to the property boundary, stormwater and combined sewers, special structures such as storage sewers, storm overflows, throttling and measuring structures, pumping stations, and the associated operating technology. The local sewer system serves the safe conveyance of foul water, stormwater, or combined sewage and links the catchment area with downstream conveyance and the wastewater treatment plant. It is subject to hydraulic, structural, and operational requirements that depend on topography, geological subsoil, building patterns, traffic areas, and the interconnected drainage system.
Configuration, systems, and components
Local sewer systems are operated as combined systems (joint conveyance of foul water and stormwater) or as separate systems (separate pipelines). Central components are shafts, line sections, connections, inlets, transfer points, and special structures for flow control. Materials range from reinforced concrete and polymer concrete to vitrified clay and plastic pipes. Slopes, pipe diameters, invert levels, and the location of house connections are hydraulically sized to prevent backwater and ensure self-cleansing.
- Shafts: access for inspection, cleaning, connections, and changes in direction or gradient
- Line sections: straight pipeline runs between two shafts
- House connections: transfer point from private property to the public network
- Special structures: stormwater detention, throttles, overflows, pumping stations, measuring points
- Materials: concrete/reinforced concrete for load-bearing capacity, vitrified clay and plastics for chemical resistance
Construction, new build, and expansion
Pipeline construction is carried out by open-cut methods, trenchless methods, or a combination of both. In inner-city situations, occupational safety, emission reduction, and the protection of adjacent infrastructure are the priorities. Where rock is present or massive concrete components must be adapted, precise, controlled methods are required. Stone and concrete hydraulic wedge splitters enable low-vibration opening of trenches and excavation pits in rock excavation and tunnel construction. When fitting shafts or creating openings in existing structures, concrete demolition shears are used for selective removal of reinforced concrete; reinforcement can be cut with steel shears or combination shears. compact hydraulic power units (power packs) supply the attachments with the required drive power, even in confined spaces.
- Surveying and staking, identification of existing lines and third-party utilities
- Pit shoring, groundwater lowering, and construction logistics
- Rock or concrete processing as needed using hydraulic wedge splitters, concrete demolition shears, and multi cutters
- Pipe laying, connection works, compaction, and surface reinstatement
- Testing, flushing, documentation, and commissioning
Confined excavation pits and inner-city constraints
In densely built street corridors, limits on noise, dust, and vibration restrict the choice of methods. Hydraulic splitting technology reduces vibration and protects adjacent utilities. Selective dismantling with concrete demolition shears minimizes uncontrolled breakage and facilitates separation of concrete and reinforcement. This approach is particularly helpful in special deployment situations, such as emergencies, when work must be performed under live traffic or in the immediate vicinity of sensitive buildings.
Rehabilitation, maintenance, and deconstruction
Regular cleaning, CCTV inspection, leakage testing, and condition assessment ensure functionality. Many defects can be rehabilitated trenchlessly (for example with lining or short liners). If replacement is unavoidable, controlled concrete demolition supports pinpoint exposure or removal. In concrete demolition and special demolition, concrete demolition shears are used to remove defective manhole walls, frames, or foundation remnants in sections. Stone and concrete hydraulic wedge splitters facilitate splitting of thick concrete slabs or opening grouted connection bodies without harmful vibrations. Combination shears, multi cutters, and steel shears separate inserts made of steel or ductile iron, such as pipe brackets, railings, sections, or beams in pumping-station structures. Cutting torches are used for work on storage or basin facilities of the local sewer system when metallic tanks or built-in parts must be dismantled.
- Manhole renewal: selective removal of frames, cones, and segment rings
- Pipe replacement: controlled opening of the excavation, trimming and removal of the old pipe
- Emergency remediation: quick, safe exposure of defective sections without collateral damage
- Decommissioning/rerouting: orderly deconstruction of old pipelines and structures
Spot repair versus full replacement
Spot repairs keep traffic and environmental impacts low when the structural analysis permits it. If the fabric is extensively damaged, replacement is advisable. In both cases, low-vibration, precise methods improve the quality of connection zones and reduce consequential damage, for example to paving, utility corridors, or adjacent foundations.
Materials, processing, and cutting techniques
Concrete and reinforced concrete characterize shafts, base slabs, supports, and special structures. Vitrified clay and plastic pipes are common in line sections and house connections. Processing is material-appropriate: splitting (stone and concrete hydraulic wedge splitters) for massive, brittle components; crushing/pressing (concrete demolition shears) for selective removal of reinforced concrete; cutting (multi cutters, steel shears) for reinforcement, sections, and metal pipes. Hydraulic power packs provide the energy supply and enable a compact, mobile way of working—especially in confined shafts. In the application area of building gutting and cutting, installations are removed before liners are inserted or new components are mounted.
Hydraulics, operation, and performance
Hydraulic performance, backwater behavior, and storage volume determine the sizing and mode of operation of the local sewer system. Flow control, sediment management, and heavy-rain preparedness influence where and how modifications are carried out. Construction interventions such as raising manhole covers, creating additional overflows, or rerouting line sections require careful work planning to maintain operations.
Testing, measuring, documenting
Cleaning, CCTV surveys, leakage tests, and gradient checks serve quality assurance. Test steps are defined on a project-specific basis and documented. Requirements from generally accepted engineering rules and municipal regulations must be observed; the notes in this text are general and not legally binding.
Occupational safety, environmental, and water protection
Work in and on the local sewer system is performed under special safety requirements: confined spaces, gas hazards, water ingress, traffic loads, and high underground utility density. Low-risk methods and appropriate tool selection protect personnel, neighbors, and the environment. Low-emission, precise working methods—especially hydraulic splitting and shear technology—reduce noise, dust, and vibration. Waste must be collected separately; concrete debris and excavated soil are properly disposed of or recycled, and contaminated materials are handled by a certified disposal company.
- Securing access points, ventilation, and gas monitoring
- Separation and blocking measures, diversion of flow (bypass)
- Protection against backwater and groundwater, emergency and special-deployment planning
- Dust and noise reduction, water protection through containment and filtration measures
Interfaces with road construction and building construction
Manhole covers are often located in carriageways or sidewalks. Construction sequences are coordinated with road construction to avoid settlements and edge formation at covers. When replacing manhole frames, concrete demolition shears facilitate precise removal without damaging the surrounding base course. Steel shears and multi cutters accelerate the separation of reinforcement and metallic inserts, for example in pumping stations, small stormwater tanks, or building penetrations.
Deep dive: Selecting suitable tools for work on local sewer systems
Tool selection depends on component, material, space constraints, and environmental risks. Concrete demolition shears are advantageous when reinforced concrete is to be removed selectively and in a controlled manner—such as on manhole cones, segment rings, base slabs, or foundation upstands. Targeted material removal facilitates exposure of reinforcement and clean creation of connections. Stone and concrete hydraulic wedge splitters are suitable when massive, brittle components or rock must be opened without disturbing vibrations, for example when widening excavation pits, opening thick concrete covers, or breaking through foundation ribs. In wet or flooded areas, the absence of spark formation and minimized vibration is a safety gain. Combination shears and steel shears complement the work by cutting reinforcing steel, sections, and built-ins; multi cutters cover pipe materials and mixed tasks. Cutting torches are needed selectively when, in the course of conversion works, metallic tanks or built-in parts in storage and basin facilities of the local sewer system must be dismantled. For rock excavation and tunnel construction—such as in underground drainage adits—hydraulic splitting methods offer a controlled alternative to percussive methods. Decision criteria include wall thickness, reinforcement ratio, brittle-fracture behavior, vibration limits, accessibility, underwater portions, protection of sensitive utilities, and the required edge quality for connecting to new components.
Typical defects and engineering treatment
Cracks, longitudinal and transverse offsets, leaking joints, root intrusion, biogenic sulfuric acid corrosion, deposits, and inflow/infiltration are common findings. Trenchless methods rehabilitate many defects; where removal is required, concrete demolition shears help precisely remove damaged concrete zones without impairing sound areas. Stone and concrete hydraulic wedge splitters open dense, rigid components when, for example, corroded supports or thick cover slabs must be replaced. Clean cut and fracture edges facilitate a load-bearing, watertight connection of new elements and improve the durability of the repair.