{"id":19343,"date":"2025-08-27T09:02:53","date_gmt":"2025-08-27T07:02:53","guid":{"rendered":"https:\/\/www.darda.de\/sewage-treatment-plant-refurbishment"},"modified":"2026-09-12T19:53:17","modified_gmt":"2026-09-12T17:53:17","slug":"sewage-treatment-plant-refurbishment","status":"publish","type":"page","link":"https:\/\/www.darda.de\/en\/knowledge\/sewage-treatment-plant-refurbishment","title":{"rendered":"Sewage treatment plant refurbishment"},"content":{"rendered":"
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The refurbishment of sewage treatment plants is a complex interplay of structural repair, selective deconstruction<\/em>, plant engineering, and occupational safety<\/em>. The aim is to ensure the long-term operational safety<\/em>, hygiene<\/em>, and cost-effectiveness<\/em> 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<\/strong> and hydraulic rock and concrete splitters<\/a><\/strong> as well as the power unit<\/strong> play an important role in this environment because they enable controlled concrete demolition<\/strong> and selective deconstruction during ongoing or partially reduced operations. In addition, compact hydraulic systems and low-spark cutting techniques help maintain process integrity in confined spaces while complying with strict emission and hygiene constraints across wastewater treatment facilities.<\/p>\n

Definition: What is meant by sewage treatment plant refurbishment?<\/h2>\n

Sewage treatment plant refurbishment encompasses all measures for restoring, upgrading, or adapting structures and components of a wastewater treatment facility. This includes concrete repair<\/strong> 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<\/strong>, as well as measures for operational safety<\/strong>. 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<\/strong> is paramount, tailored to the wastewater treatment process. In the context of sewage treatment plant refurbishment, this combination must align with tight operational windows. Interfaces to process engineering, electrical and automation systems, and temporary works must be coordinated so that treatment performance, SCADA functions, and compliance remain unaffected during each construction phase.<\/p>\n

Refurbishment goals and special framework conditions<\/h2>\n

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<\/strong>, sulfate attack, freeze-thaw de-icing cycles, biocorrosion (H\u2082S), and abrasion from sand and sludges lead to cracks, spalling, and exposed reinforcing steel<\/strong>. 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<\/strong> and disposal<\/strong>. Additional targets increasingly include energy and resource efficiency, reduction of operating risks, and regulatory compliance with water protection and occupational safety requirements throughout construction and re-commissioning.<\/p>\n

Structures and components in sewage treatment plant refurbishment<\/h2>\n

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<\/strong>; 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\u2014among them the concrete pulverizer<\/strong> and the hydraulic splitter<\/strong>\u2014allow targeted removal of damaged zones without disproportionately weakening the load-bearing structure. Access logistics, lifting points, and the routing of temporary pipelines must be planned in advance for each component to avoid process interruptions and unintended load transfers.<\/p>\n

Typical damage patterns and causes<\/h2>\n

Damage patterns range from crack formation, spalling, edge breakouts, and voids to reinforcement corrosion induced by chloride contamination<\/strong> or due to concrete carbonation<\/strong>. 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. Where damage is process-induced, remedial design should also address operational triggers, for example aeration regimes, flow velocities, or chemical dosing that accelerate wear.<\/p>\n

Planning: survey, concept, and sequence<\/h2>\n

Refurbishment begins with an investigation: visual inspections, hammer sounding, rebound hammer, carbonation depth, chloride profiles, potential measurements, rebar location, core drilling<\/strong>, 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<\/strong>, selective deconstruction of damaged zones, surface preparation, reprofiling, waterproofing\/coating, installation of new built-in component<\/strong>s, and commissioning with leakage and functional tests (including a leakage test<\/strong>). Robust planning also defines method statements, interface management with operations, and contingency measures for weather events or unexpected findings.<\/p>\n

Methods of selective deconstruction and concrete demolition<\/h2>\n

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<\/a>, selected according to component thickness, degree of reinforcement, and ambient conditions. Selection criteria include access, permissible loads on slabs and walkways, expected crack paths, and the need for low-vibration or low-spark execution in ATEX-classified areas.<\/p>\n

Concrete pulverizers in water infrastructure structures<\/h3>\n

A concrete pulverizer<\/strong> 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<\/strong>, which protects nearby waterproofing and built-in parts. Where surfaces are saturated or water-bearing, pre-breaking with a pulverizer reduces hydro-abrasive effects and minimizes secondary damage to coatings and waterstops.<\/p>\n

Hydraulic splitters for massive components<\/h3>\n

Hydraulic splitter<\/strong>s apply hydraulic splitting forces in pre-drilled holes to open up thick reinforced concrete from the inside. This method is particularly suitable for foundation<\/strong>s, thick-walled tank rings, partitions, or the floor slab<\/strong> when noise emission<\/strong> 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<\/strong>, recycling<\/strong>, and disposal<\/strong>. Optimized drilling patterns and wedge selection improve advance rates and help steer cracks away from sensitive embeds and penetrations.<\/p>\n

Hydraulic power packs and combination tools<\/h3>\n

Hydraulic power pack<\/strong>s supply mobile tools with the necessary power. In narrow shafts or around tank perimeters, compact hydraulic power units<\/a> have proven effective. Combination shears, multi cutters, and a steel shear<\/strong> 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. Electric drives produce no direct combustion-exhaust emissions at the point of use; exhaust and heat loads must be evaluated for the selected drive and ventilation concept in confined spaces, while quick-change systems shorten tool changeover times at the workface.<\/p>\n

Strip-out and cutting in plant engineering<\/h2>\n

Before concrete work, installations often need to be removed: pipelines, stainless steel<\/strong> 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<\/strong> 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\u2014compact hydraulic systems with quick coupling<\/strong> are advantageous here. Where ignition sources must be avoided, cold cutting and shearing offer advantages over abrasive cutting, provided work permits and isolation of media are verified.<\/p>\n

Surface preparation, reprofiling, and protection systems<\/h2>\n

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<\/strong> enables material-friendly exposure down to sound concrete. Exposed reinforcement is to be derusted and\u2014if necessary\u2014supplemented. Reprofiling is carried out with suitable mortar<\/strong>s, followed by application of the waterproofing layer<\/strong> or chemical-resistant coatings. Waterstops, joint profiles, and transitions to built-in parts must be detailed carefully to avoid future leaks. Quality-relevant parameters include substrate moisture, surface profile, dew point, curing conditions, and pull-off strengths, which are to be verified and documented prior to coating and before handover.<\/p>\n

Occupational safety, explosion protection, and hygiene<\/h2>\n

Strict requirements for safety and hygiene apply in sewage treatment plants. Before demolition works, areas must be cleared for gases (oxygen, H\u2082S, CH\u2084), ventilated, and secured against falls with fall protection<\/strong>. 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 enclosure<\/strong>s must be planned. Legal requirements are always to be interpreted plant-specifically; binding assessments are made by those responsible on site. Confined space entry procedures, continuous gas monitoring, hygiene and decontamination concepts, and clear permit-to-work processes are integral to safe execution during ongoing treatment operations.<\/p>\n

Environmental and resource aspects<\/h2>\n

Refurbishment should define project-specific targets for material recovery, dust, noise, vibration, water protection and energy use. Selective deconstruction facilitates clean separation of concrete, reinforcing steel, and metals. A hydraulic splitter<\/strong> can work with low vibration levels<\/strong>; effects on structures, plant components and environmental receptors must be assessed separately. Reduced dust and noise emission<\/strong> can shorten shutdown times. Processed concrete slabs can\u2014depending on regional regulations\u2014be routed to recycling<\/strong>. Additional measures include water protection at drainage points, dust suppression with minimal water usage, appropriate waste codes and chain-of-custody documentation, and the consideration of life cycle impacts when choosing repair materials.<\/p>\n

Logistics and construction sequence during ongoing operations<\/h2>\n

Sewage treatment plants often remain partially in operation during refurbishment. Temporary diversions, bypass lines, and tank changeovers must be coordinated. Compact hydraulic power pack<\/strong>s and modular tools simplify site setup on narrow tank perimeters. A reliable sequence\u2014emptying, dismantling, selective deconstruction, reprofiling, protection systems, functional testing\u2014minimizes downtime. Staging areas, crane paths, emergency access, and time-of-day work windows should be defined early to avoid conflicts with operating routes and to maintain treatment performance.<\/p>\n

Application areas and tool selection at a glance<\/h2>\n

Tool selection depends on component type, thickness, reinforcement, accessibility, and the required emission level:<\/p>\n