Drainage design

Dewatering of the area is performed to protect existing buildings as well as earthworks and building construction from the destructive action of water. To drain the incoming flow - water intakes must be made and if necessary the deep drainage of the subsoil.

Before proceeding to any construction works, all the reservoirs and watercourses located on the construction site shall be drained or regulated in order to protect against their later threat. These works are performed in accordance with the previously prepared design.

Lowering of the groundwater level may be necessary in some cases (when the groundwater makes it difficult to foundation of the designed structures and equipment or impedes execution of the excavation).

Dewatering should be carried out in a way that the structure of the subsoil under executed construction and the neighboring buildings will not be violated, and the excessive settlements of the adjacent objects as a result of generated drawdown will not occur.

Dewatering system should meet the following conditions:

- maintaining assumed in the design water levels and pore pressures without significant
  fluctuations
- ensuring continuous outflow of the given quantity of the water
- total drainage of the excavation beyond its area
- guarantee the reliability of the dewatering system

Basic regularities:

• Deep drainage of the subsoil, temporary or permanent, is made on the basis of a separate design.
• Devices for drainage of surface water (surrounding collector trenches, etc.) or drying of the area should be performed before starting the actual earthworks
• Selection of the dewatering system and its necessary efficiency must be determined on the basis of calculations.
• The effectiveness of the dewatering should be inspected by monitoring the groundwater level, pore pressures in the pores and displacements of the subsoil. Collected data should be analyzed and interpreted in order to determine the effect of dewatering on construction site conditions and the behavior of realized and nearby structures.
• Dewatering equipment should be monitored and maintained throughout the duration of their operation.
• Deep drainage determined as permanent should be equipped with devices for automatic signaling of the downtime, spare pumps and two independent power sources.