Sewer construction covers planning, new construction, rehabilitation and deconstruction of wastewater and stormwater pipelines including shafts, syphons and special structures. It combines geotechnical engineering, civil engineering (underground works), pipeline installation and demolition works. In dense urban environments, low-vibration methods, emission-reduced work practices and precise equipment are crucial—particularly for works on existing sewers, shaft structures and foundations. Where concrete and reinforced-concrete components must be opened or deconstructed in a controlled manner, sewer construction frequently uses concrete pulverizers as well as hydraulic rock and concrete splitters, often in combination with compact hydraulic power units.
Definition: What is meant by sewer construction
Sewer construction denotes the entirety of measures for the creation, upkeep and renewal of municipal and industrial drainage systems: sanitary, stormwater and combined sewers, connections, shafts, special structures (e.g., stormwater retention or storage tunnels), pressure pipelines as well as associated excavation pits, shoring systems and soil stabilization. This also includes trenchless methods such as pipe jacking and rehabilitation techniques (relining, liner, short liner) as well as the controlled demolition of damaged or obsolete sections. Sewer construction follows hydraulic, structural and operational requirements: watertightness, load-bearing capacity, self-cleaning capability, durable bedding and safe integration into the subsoil.
Construction methods in sewer construction: open-cut, trenchless and rehabilitation
The choice of method depends on subsoil, groundwater, traffic conditions, route conflicts and protected assets (buildings, utilities, water bodies). In practice, methods are combined to minimize impacts and ensure quality.
Open-cut method
Construction in an open trench is common where space is available and impacts are acceptable. Typical are engineered excavation pits with shoring, groundwater lowering, layered bedding and backfilling. When deconstructing old pipelines, foundations or shafts in the trench, pinpoint interventions are required: selective concrete crushers enable biting off and fragmenting reinforced components, while hydraulic splitters separate components and rock with minimal vibration—without impact or blasting. This protects neighboring buildings and existing utilities.
Trenchless pipeline construction
Pipe jacking, microtunneling, horizontal drilling and pipe bursting reduce surface impacts. Entry and reception shafts are still required. In rock or highly cohesive soils, local openings are created, obstacles are resolved and components are adapted during driving or shaft construction. Here, hydraulic wedge splitters and hydraulic shear are useful to remove obstacles in a controlled manner and to create cutouts in steel or concrete components.
Rehabilitation and renewal of existing assets
Rehabilitation follows the principle “as little intervention as possible.” Methods such as liners, short liners, inliners, pipe-in-pipe or partial renewal are combined with sewer shaft rehabilitation. For preparation, openings must be created, defective concrete areas removed or connections adjusted. concrete pulverizer assist in the gentle removal of damaged shaft walls, while hydraulic splitters selectively widen cracks to remove loose zones with reduced stress.
Materials and components in sewer construction
Material selection follows hydraulic, structural and chemical requirements as well as the installation situation.
- Pipe materials: concrete/reinforced concrete, vitrified clay, plastics (PE, PP, PVC-U), GFRP; pressure pipelines partly of ductile iron pipes or PE-HD.
- Shaft components: concrete and reinforced-concrete shafts, GFRP shafts, frames and cones, channel inverts, rungs and inspection openings.
- Sealing systems: sockets, sleeves, injections, shaft sealing; corrosion-protection linings in biogenically corrosive environments.
- Bedding and backfilling: frost-resistant, compactable, low-settlement; matched to pipe stiffness and traffic loads.
Excavation pits, shoring and groundwater
Excavation pits and shafts secure access to the route. Shoring systems (e.g., soldier pile walls, sheet pile wall, shoring box) stabilize the excavation boundary. With high groundwater, lowering or sealing measures are required. Local adaptations to shoring elements, temporary foundations or shaft components are often carried out with hydraulic cutting and splitting tools to limit vibration and noise.
Demolition and deconstruction of existing assets: controlled and low-vibration
Near existing utilities, gas and power routes as well as sensitive structures, low-impact methods are important. concrete pulverizer allow precise removal of shaft heads, foundation beams and upstands. hydraulic splitters work with high spreading forces and create crack corridors through which massive components are subdivided into transportable pieces—useful in narrow shafts and for special demolition. For reinforced structures, steel shear are additionally used to cut reinforcement in an orderly manner. For mixed materials and adjustment cuts in rehabilitation openings, cutting tool are suitable. Hydraulically driven tools are supplied by compact hydraulic power packs that can be positioned in shafts or at the edges of work areas.
Tools and hydraulic equipment in sewer construction
The choice of equipment depends on material, component thickness, installation position and environmental constraints (vibration, noise, emissions).
- hydraulic splitters: Crack formation in concrete and rock, ideal for pinpoint openings, shaft adaptations and controlled removal without impact energy.
- concrete pulverizer: Selective demolition of concrete shafts, foundations, inverts; combination with steel shear for cutting reinforcement.
- hydraulic shear and cutting tool: Variable cutting tasks on metal, concrete edges and plastics during gutting and cutting.
- steel shear: Deconstruction of sheet pile walls, beam sections or reinforcement in the sewer environment.
- cutting torch: special demolition when segmenting steel tanks in treatment plants or steel-pipe syphons where spark formation must be minimized.
- hydraulic power packs: Power supply for the tools mentioned; in sewer construction, compact, reliable operation in confined workspaces is essential.
Geotechnics, rock and pipe jacking
In rock or heterogeneous strata, the transition between trench excavation, shaft construction and driving is demanding. Local rock outcrops, boulders or concrete layers from earlier construction phases can be removed with rock wedge splitters and hydraulic splitters with reduced stress. This supports rock excavation and tunnel construction for entry shafts and short drives and reduces risks to surrounding buildings.
Planning: hydraulics, gradient and operation
Hydraulic design covers design flows, gradients, degrees of filling, air management and self-cleaning. Route selection considers utility crossings, safety distances, accessibility for inspection and maintenance. Construction phasing and traffic concepts minimize closures. For interventions in existing sewers, diversion measures (bypasses) and provisional operating conditions must be ensured.
Quality assurance, testing and documentation
Quality results from coordinated execution and robust evidence:
- Preparatory checks: subsoil, utility records, locating, damage classification, conveyed media.
- Execution control: bedding layers, compaction, component dimensions, correct integration of sealing systems.
- Acceptance: leakage tests and pressure tests, CCTV inspection, evenness and gradient, settlement control, as-built documentation.
For rehabilitations, material certificates and installation logs are added; for deconstruction, a complete disposal documentation chain must be observed.
Safety and environmental protection
Occupational safety, emission control and water protection have high priority in sewer construction. This includes secured access, fall protection, controlled ventilation in shafts, ATEX zone requirements in hazardous areas, dust suppression and noise reduction measures, as well as soil and groundwater protection. Hydraulic splitting and cutting methods contribute to a safe, environmentally compatible workflow through low vibration levels and metered force transmission. Legal and normative requirements must be checked project-specifically and implemented appropriately.
Special applications and special operations
In the environment of sewage treatment plants, stormwater tanks and syphon installations, tailored solutions are required. For the deconstruction of steel components, tanks or fittings, steel shear and cutting torch are suitable. In confined shafts with limited load capacity of the work platforms, compact, hydraulically powered tools offer advantages. For gutting works and cut of openings in existing sewers, concrete pulverizer and hydraulic splitters ensure controlled cuts and stress-relief strategies—important for safeguarding adjacent structures.
Best practices in sewer construction
- Early coordination with other network owners to minimize conflicts.
- Align subsoil and groundwater strategy with construction method, shoring and bedding.
- Prioritize low-vibration methods for work on existing assets and in sensitive locations.
- Open components only as far as required for installation or rehabilitation; use controlled demolition instead of area-wide demolition.
- Size hydraulic tools to suit the task and operate them with suitable hydraulic power packs.
- Maintain a complete testing and documentation chain: from preparation through acceptance.