Drainage and dewatering calculations
Hydrogeological calculations of drainage and groundwater lowering for excavations, basements and sites, including inflow and pumping capacity.
Licensed service · EL-845/2026
Where groundwater is shallow, the water level must be lowered temporarily or permanently to dig an excavation or keep a basement dry. It is important to calculate in advance how much water will flow in, how many wells or wellpoints are needed, the pump capacity and the effect of the system on nearby buildings. Without such calculations dewatering is either insufficient or needlessly expensive.
The calculations are based on the results of geotechnical and hydrogeological surveys, especially pumping tests. Taking into account the size of the excavation, foundation depth, aquifer thickness and permeability, we determine inflow, the drawdown curve and the required lowering. Alongside analytical methods, numerical modelling can be applied in complex conditions.
Permanent drainage systems, such as perimeter, blanket or ring drains, are designed to protect basements and foundations from groundwater over the long term. The report gives recommendations on drain pipe layout, depth, gradient and water discharge.
Lowering the water table can cause additional soil settlement and deformation of neighbouring buildings. The calculation therefore assesses the zone of influence and, where needed, recommends geodetic monitoring of nearby structures during the works. Calculations are carried out in close cooperation with the designer according to the applicable codes (AzDTN/SNiP).
When you need it
- Excavating below the groundwater table
- Permanent drainage of basements and underground car parks
- When an existing basement is flooded
- Designing flood protection for a site
- Trenching for utilities below the water table
What's included
- Analysis of input data
- Calculation of inflow into the excavation
- Drawdown curve and radius of influence
- Number and layout of wells or wellpoints
- Pump capacity calculation
- Parameters of permanent drainage
- Assessment of impact on neighbouring buildings
How we work
- Obtaining design and survey materials
- Additional pumping tests if needed
- Choosing the calculation scheme
- Calculations and comparison of options
- Report and advice for the designer
Deliverables
- Hydrogeological calculation report
- Dewatering system layout
- Inflow and pump capacity figures
- Drainage and monitoring recommendations
