An approximate model on three-dimensional groundwater infiltration in sewer systems.

Area of Science:

• Environmental Engineering
• Hydrology
• Civil Engineering

Background:

• Groundwater infiltration into sewer systems is a significant issue, leading to economic losses.
• Existing models often lack the complexity to accurately represent infiltration through defects like cracks.

Purpose of the Study:

• To develop a three-dimensional analytical expression for calculating steady-state groundwater infiltration rates into sewer systems.
• To extend a previous two-dimensional model to simulate infiltration through orifice defects.

Main Methods:

• Developed a 3D analytical model incorporating soil head loss (using Ergun equation with viscous and inertial terms) and orifice loss.
• Validated the derived analytical expression with experimental results.
• Introduced and analyzed a new OS number (ratio of orifice loss to soil loss).

Main Results:

• The 3D model accurately calculates steady-state groundwater infiltration rates.
• The Ergun equation integration extends the model's applicability by including inertial soil loss.
• Analysis of the OS number indicates soil head loss is the dominant factor in most real-world scenarios.

Conclusions:

• The new 3D analytical model provides a more comprehensive approach to understanding groundwater infiltration into sewers.
• The model's ability to incorporate both soil and orifice resistances enhances its practical utility.
• Findings emphasize the critical role of soil properties in controlling infiltration rates.