The main application of the mobile geo-electrical measurement is the detection of the presence and determining the location of leakage in sewer systems. To do so, this method relies on the increase in the measured electrical current between an electrode inside and an electrode outside the sewer system. To use this technique for the quantification of leakages further assumptions on the measured current are required. In this study, a model to simulate the geo-electrical measurement system is developed. Laboratory experiments are conducted to investigate the influence and contribution of the model components on the measured current and the validity of the assumptions. The experimental results demonstrate that multiple components significantly contribute to the measured current apart from the leakage in the pipe. As a consequence, the properties of the leakage in the pipe are likely to be significantly under- or overestimated in most measuring systems currently applied in practice.

Due to the ageing of our underground wastewater infrastructure, leakage of sewers and pressure mains and subsequent infiltration or exfiltration are becoming an increasingly important issue. Herein, we present a novel method to detect and potentially quantify exfiltration from sewer systems under variable flow conditions; the DEST method. The DEST method is based on the principle of setting up a mass balance of a tracer substance. At an upstream point a tracer is injected in a sewer with a constant rate for a certain period, subsequently downstream high frequent time discrete grab samples are combined with discharge measurements to complete the mass balance. The method is applied on a sewer section in Loenen (NL) to investigate its feasibility. Two different tracers are used; Lithium chloride and Deuterium. Preliminary results indicate that both tracers show similar behaviour at the downstream measurement point. Final lab results are expected at the end of March, allowing in depth analysis of the experimental results with a focus on the measurement uncertainty.