Dewatering is the process of removing groundwater or surface water from a construction site, mine, or other work area. Proper dewatering ensures safe working conditions and structural integrity of excavations.
Key Applications
Construction sites, basement excavations, tunneling projects, mining operations, and emergency flood response all require effective dewatering solutions.
Why Dewatering Matters
Safety
Prevents trench collapses, soil instability, and equipment hazards
Productivity
Allows uninterrupted work in excavations and foundations
Quality
Reduces risk of concrete washout and soil erosion
Regulatory Compliance
Helps meet environmental discharge requirements
Types of Dewatering
Open Sump Pumping
Water is collected in sumps and pumped out using submersible or surface pumps. Simple and cost-effective for moderate water inflow.
Wellpoint Systems
Network of small wells connected to a header pipe and vacuum pump. Effective for shallow groundwater in sandy soils.
Deep Well Systems
Individual wells with submersible pumps for deep groundwater lowering. Used when wellpoints can’t reach required depth.
Eductor Systems
Uses high-pressure water to create vacuum in wells. Ideal for fine-grained soils with low permeability.
Pump Types for Construction Dewatering
Centrifugal Auto-Prime Pumps
Reliable for handling varying water levels and air entrainment. Ideal for most construction dewatering applications.
Diesel Trailer Pumps
Portable and powerful for large flows and remote sites. No mains power required.
Submersible Electric Pumps
Compact, safe, and effective in confined spaces. Low noise for urban sites.
High-Head Pumps
Needed when water must be lifted or discharged over long distances or significant elevation.
Key Selection Criteria
When selecting a pump for dewatering, consider these critical factors:
Flow Rate
Match pump capacity to expected inflow of groundwater. Allow 25% safety margin for peak conditions.
Total Dynamic Head (TDH)
Include suction lift, discharge head, and pipe friction losses in your calculations.
Solids Handling
Choose trash or slurry pumps if water contains debris, sand, or silt. Check solids passage size.
Power Source
Diesel for mobility and remote sites. Electric for quiet operation and low running cost.
Noise Levels
Acoustic enclosures may be required in urban areas or near residential properties. Check local noise regulations before selecting equipment.
Best Practices for Site Dewatering
Position suction intakes in sumps to collect water efficiently
Use strainers to prevent debris from damaging the pump
Install suction hoses with minimal bends to reduce friction losses
Monitor discharge water quality to comply with environmental requirements
Regularly check for air leaks in suction lines to prevent loss of prime
Maintain standby pumps for emergency backup in high-risk sites
Environmental & Regulatory Considerations
Dewatering operations must comply with environmental regulations. Discharge water often requires treatment before disposal.
Sediment Control
Sediment-laden discharge may require settlement tanks or silt bags before release
Contaminated Water
Contaminated groundwater may need treatment before disposal – test water quality early
Permits & Regulations
Local councils or environmental authorities often regulate discharge locations and flow rates
Settlement Risk
Lowering groundwater can cause soil settlement affecting nearby structures. Always assess settlement risk and monitor adjacent buildings during dewatering operations.
Summary
Construction dewatering is more than just removing water — it’s about ensuring site safety, protecting structures, and meeting environmental obligations.
Key Takeaways
- Choose the right dewatering method based on site conditions and soil type
- Select pumps considering flow rate, TDH, solids handling, and power source
- Follow best practices: sumps, strainers, minimal bends, standby equipment
- Comply with environmental regulations for discharge water quality