Hydraulic modelling of sewage exfiltration
Christian Karpf1, Jens Traenckner, Peter Krebs
1Institute for Urban Water Management, Dresden University of Technology, D-01062 Dresden, Germany. christian.karpf@tu-dresden.de
Summary
Wastewater exfiltration from sewer networks can harm soil and aquifers. This study reveals that unsaturated soil conditions increase initial exfiltration rates, while matrix potential tightens the colmation layer, impacting leakage.
Area of Science:
- Environmental Engineering
- Hydrogeology
- Soil Science
Background:
- Sewer exfiltration poses risks to soil and groundwater resources.
- Existing models often simplify soil and colmation layer characteristics.
- Understanding exfiltration dynamics is crucial for environmental protection.
Purpose of the Study:
- To investigate the influence of soil water content on wastewater exfiltration rates.
- To develop a colmation model for predicting layer thickness and conductivity.
- To enhance the accuracy of sewer exfiltration modeling.
Main Methods:
- Utilized HYDRUS 1D modeling to simulate exfiltration under varying soil moisture conditions.
- Conducted experimental investigations to assess the impact of matrix potential on the colmation layer.
- Developed a new colmation model based on experimental findings.
Main Results:
- Initial exfiltration rates were higher under unsaturated soil conditions compared to saturated conditions.
- Experimental data showed that matrix potential enhances the sealing capacity of the colmation layer.
- The developed colmation model allows for the calculation of colmation layer thickness and conductivity.
Conclusions:
- Soil water content significantly affects sewer exfiltration rates, with unsaturated conditions leading to higher initial leakage.
- Matrix potential plays a key role in the colmation process, improving the impermeability of the sewer lining.
- The new colmation model provides a more refined tool for assessing and managing sewer exfiltration risks.
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