A New Concept for Placing Coupons and Sensors for Decontamination Verification

Sentinel coupon devices may be installed in water distribution systems for decontamination surveillance. They give the possibility to extract samples and perform off-line laboratory analysis. The objective of this research work is to develop a concept for positioning sentinel coupons and sensors at representative and indicative locations in the water distribution system. A new integer linear programming formulation is proposed that is a weighted maximum coverage problem with weights that favor places where contaminant concentration is higher and the shear stress is lower. Extended period simulation models as contamination events are used inside a Monte Carlo simulation to calculate the averaged weights and the coverage matrix. The method was validated in a case study from the literature and applied to larger complex and detailed networks. The solution looks to favor sink nodes with long water paths. Finally, this new optimal placement problem was found to yield solutions that are significantly different from early-warning designs.