Aquifers are central to planning, demolition, and underground construction projects. They control availability, flow paths, and the protection needs of groundwater—and thus the boundary conditions for processes such as concrete demolition, rock cutting/processing, tunnel excavation, or natural stone extraction. Anyone who separates, splits, or cuts materials must understand the hydrogeological properties of the subsurface in order to secure water pathways, prevent inputs, and manage construction site water properly. Especially with low-vibration methods such as hydraulic splitting or shear-based demolition—for example with concrete demolition shears or hydraulic rock and concrete splitters from Darda GmbH—risks to aquifers can be made technically manageable when they are incorporated early into work planning.
Definition: What is meant by aquifer
An aquifer is a geological body that stores and transmits water. It consists of porous or fractured rocks or unconsolidated sediments with sufficiently high hydraulic conductivity. A distinction is made between unconfined (free water table) and confined aquifers (artesian), which are bounded by low-permeability layers. Core properties are porosity, permeability, storage capacity, and anisotropy. Together they determine how quickly and in which direction groundwater flows—and how sensitively an area reacts to construction measures, vibrations, dewatering, or infiltration.
Hydrogeological fundamentals and types of aquifers
Hydrogeologically, aquifers are classified according to their pore space and structure. This categorization helps select suitable demolition and splitting methods as well as plan groundwater control and protection measures in concrete demolition and specialist deconstruction, in rock demolition and tunnel construction, and in natural stone extraction.
Porous-media aquifers
Unconsolidated rocks such as sands and gravels convey water through interconnected pore spaces. They respond sensitively to dewatering: cones of depression can develop over wide areas, fine sediments may be mobilized, and turbidity can occur. For demolition of massive concrete structures or foundation removal, a carefully tuned groundwater control and low-vibration material removal—such as stepwise shear demolition with concrete demolition shears—are recommended to minimize settlement and particle migration.
Fractured and karst aquifers
Hard rocks such as granite, gneiss, or limestone convey water through fractures, joints, or karst cavities. Preferential flow paths with sometimes high velocities dominate. For rock demolition and tunnel construction this means unforeseen inflows, pressurized water, and hydraulic short-circuits are possible. Mechanical methods such as stone and concrete splitters or stone splitting cylinders allow controlled opening along existing discontinuities, which can limit additional fracture formation and shock waves. In karst areas, sealing measures (e.g., grout curtains) and close-meshed monitoring are particularly important.
Confined and unconfined aquifers
Unconfined aquifers have a free water table; confined aquifers are under excess pressure and are overlain by weakly permeable horizons. Interventions in confined systems entail the risk of sudden inflows and hydraulic heave. Excavation pits then need to be secured with removable impermeable base slabs or cut-off walls. During strip-out and cutting in existing structures, pressurized water can emerge at openings; precise, low-vibration cuts—e.g., with concrete demolition shears or Darda GmbH Multi Cutters—reduce the risk of uncontrolled water pathways.
Hydraulic parameters
- Hydraulic conductivity (kf): determines flow velocity and drawdown extent.
- Porosity and effective porosity: define storage and transport volume.
- Storage capacity/storativity: important for pumping and dewatering concepts.
- Anisotropy/heterogeneity: govern directions of preferential flow paths.
Relevance for concrete demolition, rock demolition, and tunnel construction
On construction sites that intersect aquifers, method, sequence, and energy input influence safety and the protection of the water regime. Depending on rock fabric, groundwater conveyance, and the construction task, different solutions are appropriate.
Low-vibration methods and water pathways
Low-vibration methods—for example shear demolition with concrete demolition shears or controlled splitting with stone and concrete splitters—limit impact and vibrational energy. This reduces the likelihood of widening existing fractures or creating new crack networks that could act as short-circuits in the aquifer. Such methods are often advantageous in water protection zones and near sensitive infrastructure.
Excavation pits, groundwater control, and cones of depression
In porous-media aquifers, groundwater lowering can cause settlement and turbidity. Technical options include wellpoint systems, excavation pit enclosures, or impermeable base slabs. Demolition steps are synchronized with water management: material separation, temporary storage, and loading take place on sealed surfaces, drop heights are kept small to limit percolation water. Hydraulic power packs are positioned so lines are short and tight; drip losses must be prevented by containment systems.
Karst and fracture water in tunnel construction
In rock demolition and tunnel construction, openings created by advance excavation intersect pressurized fractures. Ahead-of-face exploratory drilling, piezometers, pre-injection, and segmented splitting reduce risk. Mechanical separation and splitting methods enable controlled exposure while inflows are captured and discharged in parallel. Adjusting the sequence—split, secure, discharge—stabilizes the system and protects the aquifer from turbidity inputs.
Planning and permitting in a water protection context
Measures in or near aquifers require coordinated planning and—depending on the region—regulatory permits. Requirements on water protection areas, groundwater control, discharge, and reintroduction must be observed. Legal frameworks vary regionally; project-specific coordination is essential.
- Pre-investigation: evaluation of maps, borehole logs, groundwater levels, and substance data.
- Field investigation: dynamic probing, investigation boreholes, pumping/slug tests, tracer tests where appropriate.
- Monitoring: installation of piezometers, online water levels, and turbidity control.
- Risk analysis: assessment of settlement, inputs, inflows, hydraulic short-circuits.
- Method selection: prioritize low-vibration methods (e.g., shear demolition, splitting techniques) in sensitive areas.
- Emergency plan: materials and workflow for immediate measures (sealing, diversion, grouting, retention).
Practical measures to protect groundwater on site
Protective measures combine technical, organizational, and operational precautions. The goal is to safeguard the aquifer from turbidity and contaminant inputs and to control water levels.
- Sealing: tight working surfaces, edge seals, containment trays for power units and couplings.
- Water management: separate collection of stormwater, percolation water, and process water; sediment separators and filtration stages prior to discharge.
- Sequencing: small-scale, sectional demolition; splitting and shear cycles in controlled intervals.
- Material management: rapid removal, covered temporary storage, do not introduce fines into open fracture zones.
- Technology choice: use mechanical methods such as concrete demolition shears, stone and concrete splitters, and stone splitting cylinders where explosives or highly percussive methods could increase water-management risks.
- Documentation: complete records of water levels, turbidity, flow rates, and methods used.
Measurements, tests, and monitoring
Robust monitoring makes changes visible at an early stage and enables control during ongoing operations.
- Piezometers and gauges: continuous recording of water levels and pressure conditions (including with data loggers).
- Hydraulic tests: step-drawdown and long-term pumping tests, slug tests; interpretation of kf, storativity, and radii of influence.
- Quality control: conductivity, pH, turbidity, and selected ions; if needed, particulate analytics.
- Flow measurement: recording of inflow and discharge volumes at dewatering and reintroduction points.
- Visual inspection: turbidity plumes, unexpected inflows, settlement cracks along structure edges.
Special application areas: strip-out and cutting, natural stone extraction, special operations
Depending on the task, hydrogeological priorities differ—from processing existing structures to raw material extraction.
Strip-out and cutting in existing structures
During selective deconstruction near groundwater, precise, low-vibration cuts are important. Tools such as concrete demolition shears, Multi Cutters, steel shears, and tank cutters from Darda GmbH enable material-appropriate separation without thermally induced emissions or explosive media. Water used for dust suppression must be collected separately and clarified before discharge.
Natural stone extraction
In quarries with open water flow, splitting with stone splitting cylinders and stone and concrete splitters can exploit natural fractures and reduce impact loads. This lowers the risk of introducing fines into water pathways. Runoff from the working area should be routed through settling stages to avoid turbidity in the aquifer.
Special operations
In contaminated zones or in the immediate vicinity of abstraction wells, even closer control is required: sealed working areas, closed shearing systems, redundant retention volumes, and sealing agents immediately available. Mechanical methods with controlled energy input facilitate compliance with strict thresholds.
Typical risks and how to avoid them
Risks can be significantly reduced through appropriate methods, sequencing, and water management.
- Cones of depression and settlement: minimal drawdown targets, temporary sealing systems, re-injection (infiltration) only after verification.
- Turbidity backflow: multi-stage sedimentation/filtration; do not introduce fines into open fractures.
- Hydraulic short-circuits: low-vibration demolition techniques, crack monitoring, grouting of disturbed zones.
- Unexpected inflows: probe drilling, pre-injection, readiness for immediate measures.
- Contaminant inputs: sealed equipment areas, leakage monitoring, safe material storage, and rapid cleanup of even minor drips.
Documentation, aftercare, and deconstruction of water-handling systems
After completion, temporary dewatering systems must be dismantled in an orderly manner and monitoring points properly sealed. Accompanying documentation—water level trends, turbidity, flow rates, and methods used—serves as evidence that the aquifer was protected. A short post-operation monitoring phase can help detect delayed effects and adjust measures if necessary.
Terminology distinctions in the water cycle
Aquifers are to be distinguished from aquitards and semiconfining layers; aquicludes are considered practically impermeable. In addition, local perched or hillside water horizons exist above the saturated zone. These classifications are important to align demolition and splitting sequences, groundwater control strategies, and the use of concrete demolition shears and stone and concrete splitters with the hydrogeological boundary conditions.