The refurbishment of sewage treatment plants is a complex interplay of structural repair, selective deconstruction, plant engineering, and occupational safety. The aim is to ensure the long-term operational safety, hygiene, and cost-effectiveness of wastewater treatment. Water-exposed concrete structures, steel and pipe constructions, and sensitive process sequences meet construction interventions that must be as low in vibration, low in dust, and precise as possible. Tools such as a concrete pulverizer and hydraulic rock and concrete splitters as well as the power unit play an important role in this environment because they enable controlled concrete demolition and selective deconstruction during ongoing or partially reduced operations.
Definition: What is meant by sewage treatment plant refurbishment
Sewage treatment plant refurbishment encompasses all measures for restoring, upgrading, or adapting structures and components of a wastewater treatment facility. This includes concrete repair in aeration and secondary clarifier tanks, the deconstruction of damaged components, the replacement or adaptation of steel and pipe constructions, the renewal of coatings and the waterproofing layer, as well as measures for operational safety. Depending on the damage pattern, the spectrum ranges from targeted local interventions to comprehensive upgrades including selective deconstruction and rebuilding. In practice, a targeted combination of demolition, building gutting, cutting, and structural repair is paramount, tailored to the wastewater treatment process. In the context of sewage treatment plant refurbishment, this combination must align with tight operational windows.
Refurbishment goals and special framework conditions
Typical goals include extending service life, increasing operational safety, adapting to new treatment stages (e.g., micropollutant removal), and reducing leaks and infiltration. Sewage treatment plants are strongly exposed to water and chemicals; concrete carbonation, sulfate attack, freeze–thaw de-icing cycles, biocorrosion (H₂S), and abrasion from sand and sludges lead to cracks, spalling, and exposed reinforcing steel. Refurbishment often occurs during ongoing operations with tightly scheduled shutdown and switchover windows. This creates a need for precise, low-emission methods—such as controlled splitting or crushing of concrete with hydraulic tools—as well as cleanly separated material streams for recycling and disposal.
Structures and components in sewage treatment plant refurbishment
Sewage treatment plants comprise a wide variety of structure types with specific requirements: rectangular aeration tanks, circular secondary clarifiers, digesters, inlets and pumping stations, channel systems, shaft structures, screens and grit chambers, sludge storage or thickening systems, as well as pipe bridges and steel walkways. Construction interventions must take these differences into account: circular tanks demand segmented work along the wall coping; tanks with coatings require material-friendly removal methods; digesters require strict gas and explosion protection concepts (e.g., ATEX zone considerations). Tools for selective deconstruction—among them the concrete pulverizer and the hydraulic splitter—allow targeted removal of damaged zones without disproportionately weakening the load-bearing structure.
Typical damage patterns and causes
Damage patterns range from crack formation, spalling, edge breakouts, and voids to reinforcement corrosion induced by chloride contamination or due to concrete carbonation. Abrasion occurs in channels and inlets; chemical and microbiologically induced corrosion appears in splash zones. Joint leakage and local leaks caused by faulty built-in parts are also common. Causes lie in decades of exposure, load changes, material fatigue, settlements, or formerly insufficient details (drainage, edges, waterstops). A systematic condition assessment forms the basis of every refurbishment plan.
Planning: survey, concept, and sequence
Refurbishment begins with an investigation: visual inspections, hammer sounding, rebound hammer, carbonation depth, chloride profiles, potential measurements, rebar location, core drilling, and, if necessary, sampling for laboratory tests. This is followed by damage classification, prioritization, and a refurbishment concept with construction phases, closure times, and diversion concepts. The sequence of typical measures: emptying/desludging, temporary wastewater bypassing, protection and protective enclosure, selective deconstruction of damaged zones, surface preparation, reprofiling, waterproofing/coating, installation of new built-in components, and commissioning with leakage and functional tests (including a leakage test).
Methods of selective deconstruction and concrete demolition
In environments with sensitive processes and limited shutdown windows, low-emission methods are advantageous. For controlled concrete removal, various hydraulic tools and separation methods are available, as used in concrete demolition and deconstruction, selected according to component thickness, degree of reinforcement, and ambient conditions.
Concrete pulverizers in water infrastructure structures
A concrete pulverizer enables targeted biting and crushing of concrete, including controlled exposure of the reinforcement. In clarifier tanks, this allows removal and rehabilitation of spalled sections along damaged edge areas, upstands, or local defects without large-scale intrusion into sound areas. The advantage lies in precise material separation and reduced low vibration levels, which protects nearby waterproofing and built-in parts.
Hydraulic splitters for massive components
Hydraulic splitters apply hydraulic splitting forces in pre-drilled holes to open up thick reinforced concrete from the inside. This method is particularly suitable for foundations, thick-walled tank rings, partitions, or the floor slab when noise emission and dust need to be limited. Thanks to the controlled crack path, adjacent structural parts are better protected; the fragmented geometry also facilitates construction waste separation, recycling, and disposal.
Hydraulic power packs and combination tools
Hydraulic power packs supply mobile tools with the necessary power. In narrow shafts or around tank perimeters, compact hydraulic power units have proven effective. Combination shears, multi cutters, and a steel shear cut reinforcement, guardrails, gratings, profiles, and pipelines. In special cases, tank cutters can be used for metallic vessels or thick-walled steel components, provided gas clearance measurements and ATEX zone requirements are fulfilled.
Strip-out and cutting in plant engineering
Before concrete work, installations often need to be removed: pipelines, stainless steel components, mixers, scraper bridges, guardrails, rungs, cable tray systems. The selective cut-out is preferably low-spark and with controllable cutting speed. Tools such as a steel shear or multi cutters enable clean cuts on profiles and sheets, simplifying subsequent surface preparation and installation. During building gutting in shafts and channels, spatial constraints must be considered—compact hydraulic systems with quick coupling are advantageous here.
Surface preparation, reprofiling, and protection systems
Following deconstruction comes the creation of bondable, cleanable surfaces. Depending on the system, water jetting, milling, or chiseling are used; in sensitive areas, pre-breaking with a concrete pulverizer enables material-friendly exposure down to sound concrete. Exposed reinforcement is to be derusted and—if necessary—supplemented. Reprofiling is carried out with suitable mortars, followed by application of the waterproofing layer or chemical-resistant coatings. Waterstops, joint profiles, and transitions to built-in parts must be detailed carefully to avoid future leaks.
Occupational safety, explosion protection, and hygiene
Strict requirements for safety and hygiene apply in sewage treatment plants. Before demolition works, areas must be cleared for gases (oxygen, H₂S, CH₄), ventilated, and secured against falls with fall protection. In digester and sludge environments, explosion protection (ATEX zone) must be observed. Hydraulic tools reduce sparking and, when used correctly, are low-emission. Personal protective equipment, access concepts, rescue plans for shafts, and media-resistant protective enclosures must be planned. Legal requirements are always to be interpreted plant-specifically; binding assessments are made by those responsible on site.
Environmental and resource aspects
Refurbishment should conserve resources and minimize environmental impact. Selective deconstruction facilitates clean separation of concrete, reinforcing steel, and metals. A hydraulic splitter works with low vibration levels, protecting adjacent ecosystems, structures, and plant components. Reduced dust and noise emission can shorten shutdown times. Processed concrete slabs can—depending on regional regulations—be routed to recycling.
Logistics and construction sequence during ongoing operations
Sewage treatment plants often remain partially in operation during refurbishment. Temporary diversions, bypass lines, and tank changeovers must be coordinated. Compact hydraulic power packs and modular tools simplify site setup on narrow tank perimeters. A reliable sequence—emptying, dismantling, selective deconstruction, reprofiling, protection systems, functional testing—minimizes downtime.
Application areas and tool selection at a glance
Tool selection depends on component type, thickness, reinforcement, accessibility, and the required emission level:
- Concrete demolition and special demolition: a concrete pulverizer for precise component removal; a hydraulic splitter for thick, heavily reinforced zones.
- Strip-out and cutting: a steel shear and multi cutters for profiles, guardrails, beams, and pipelines; combination shears for mixed materials.
- Special use: tank cutters for metallic vessels or thick-walled components after gas clearance and safety release (ATEX zone).
- Rock breakout and tunnel construction: rock hydraulic splitters for geological obstacles in inlet or outlet structures.
- Natural stone extraction: relevant for extensions when excavation pits must be created in rock.
Quality assurance and documentation
Ensuring refurbishment quality includes approvals after defined removal limits, pull-off adhesion tests and leakage tests, visual inspections of reprofiling, and documentation via photo records. For load-bearing components, stability verification is required; adjustments are made in coordination with planning and site management. Digital as-built data support future maintenance planning.
Practical guide: step by step
- Record the existing condition: review, measurements, material samples, rebar location.
- Define the refurbishment goal: functional requirements, closure times, bypasses.
- Determine methods: concrete pulverizer for targeted removal, hydraulic splitter for massive areas, supplementary steel cutting for metal.
- Plan safety: gas clearance measurements, ventilation, ATEX zone measures, traffic routes, PPE.
- Execute selective deconstruction: construction waste separation, recycling, dust suppression, and noise reduction measures.
- Prepare surfaces and reprofile: bondable substrates, corrosion protection, waterproofing layer systems.
- Completion: functional and leakage tests, documentation, monitoring.
The role of Darda GmbH in the context of sewage treatment plant refurbishment
Darda GmbH stands for hydraulic tools that enable selective concrete demolition, splitting, and cutting in the context of sewage treatment plant refurbishment. The focus is on technical suitability for sensitive water infrastructure structures: controlled splitting forces, precise work with a concrete pulverizer on concrete, and efficient separation of metal components with a steel shear. In this way, damage zones can be treated appropriately to the material and construction phases can be safely integrated into plant operations—without promotional exaggeration, but as a factual response to the requirements of wastewater infrastructure.