Swimming Pool

Waterproofing

Designing swimming pool walls requires carefully accounting for hydrostatic pressure exerted by water inside the pool and lateral earth pressure (potentially coupled with negative hydrostatic pressure from groundwater) from the surrounding soil. Here's how these pressures interact and the design considerations

1. Positive Hydrostatic Pressure

• Source: Water inside the pool exerts pressure on the walls.
• Implication: The wall must have sufficient structural strength (usually concrete reinforced with steel) to resist the outward force from the water.

2. Negative Hydrostatic Pressure (From Soil/Groundwater)

• Source: Water in the surrounding soil can create pressure against the outer surface of the pool walls.
• Factors:
  • If the groundwater level is high, this pressure can become significant.
  • Poor drainage can exacerbate this condition.
• Solution:
  • Waterproofing: Add a waterproof membrane on the exterior to prevent water ingress.
  • Drainage System: Incorporate a French drain or similar system to reduce hydrostatic pressure.
  • Counterweights: Use the pool's own water as a counterbalance to the external pressure.

3. Lateral Earth Pressure

• Source: Soil exerts pressure depending on its type, density, and moisture content.
• Pressure Distribution:
  • Active Pressure: When the wall moves away from the soil.
  • Passive Pressure: When the wall resists soil movement.
  • At-Rest Pressure: When the wall is stationary.
• Solution:
  • Walls must be thick enough to resist these loads.
  • Retaining wall design principles (e.g., stability against overturning, sliding, and bearing capacity) should apply.

4. Combined Effects

• The total load on the walls includes both water pressure from inside and external pressures (soil and water).
• Structural design must consider worst-case scenarios:
  • Pool is full, and soil/groundwater pressure is high.
  • Pool is empty, and soil/groundwater pressure dominates.

5. Design Considerations

• Material Selection:
  • Use reinforced concrete (RC) with appropriate grades.
  • Ensure steel reinforcement is adequate for tensile stresses.
• Waterproofing:
  • Internal (positive side) and external (negative side) waterproofing layers are crucial.
• Drainage:
  • Install sub-drainage systems to manage groundwater.
• Foundation:
  • Ensure the base slab can counteract uplift forces from groundwater.
• Testing:
  • Conduct hydrostatic testing to verify performance before commissioning.