Estelle was a bachelor's degree student in water egineering working in the modelEAU as a trainee. Her work was divided in two categories, both related to data quality evaluation for on-line sensors. The first part of her work was to assist Mathieu Beaupré in the data gathering of on-line nitrate sensors. The second part of her work was oriented on sensor's response time. Estelle was gathering data on the response time behavior of different sensors. These data were then integrated to sensor characteristics simulations in order to set up models on the impact of sensor faults and their response time on the process performance.