Smart Stormwater Management: Why Infiltration Testing is Key to a Successful Project
As a consequence of global climate change, extreme rainfall events are becoming increasingly frequent each year. To prevent the adverse effects of heavy rainfall on existing and planned structures, it is essential to construct a well-dimensioned stormwater infiltration system. When designing such a system, the main input parameter (alongside rainfall duration and intensity) is the hydraulic conductivity of the foundation soil. Additionally, careful attention must be paid to the position of the system to ensure it does not potentially endanger neighboring properties.
During the design phase, it is crucial to conduct water infiltration testing to dimension the system properly. These tests can be performed on the surface within test pits or, in the case of poor surface permeability, through boreholes. If the soil at a shallow, reachable depth (up to approximately 4 meters) does not meet the requirements, deep boreholes are drilled to enable deep stormwater infiltration.
The locations for deep infiltration boreholes are determined based on available space and geophysical survey results, which provide precise data on the depths and positions of permeable soil layers. Based on the drilling results and the in-borehole permeability tests, the exact number and diameter of the deep infiltration boreholes are calculated. These investigations of infiltration systems are conducted by hydrogeologists, who also design deep infiltration boreholes.
Why Precise Dimensioning Matters?
A system built based on guesswork or generic templates carries immense risks. If under-dimensioned, the system will fail to absorb sudden torrents of water, leading to yard flooding, waterlogged parking lots, or water entering basements. On the other hand, an over-dimensioned system unnecessarily inflates project costs.
A particularly critical aspect is the exact discharge location. Improper management and discharge of stormwater runoff can lead to sudden soil saturation, which can directly trigger landslides in areas prone to slope instability. This puts not only the investor’s facility at risk, but also endangers the surrounding community infrastructure and neighboring properties.
A properly engineered system brings key benefits:
- Long-term structural and slope stability: It prevents water from undermining foundations, washing away fine soil particles, and triggering landslides or slope failures.
- Preserving the natural water cycle: Water is returned directly to the underground water table where it fell, rather than overloading the public sewage and drainage network.
- Financial optimization: By optimizing the number and depth of boreholes through rigorous hydrogeological calculations, you invest exactly what is needed for maximum efficiency.
Conclusion
A successful stormwater infiltration system does not begin with construction work, but with high-quality field data. By engaging experts and conducting geophysical and hydrogeological testing, you ensure that your investment is safe, geotechnically stable, and resilient to increasingly severe climate challenges.
