Development of a Decision Making Support System for Efficient Rehabilitation of Sewer Systems

Abstract

The main objective of sewer rehabilitation is to improve its function while eliminating inflow/infiltration (I/I). If we can identify the amount of I/I for an individual pipe, it is possible to find the distribution of the total I/I over the entire sewer system. With this information we identify which sub-area is more critical than others. However, in real, the amount of I/I for an individual pipe is almost impossible to be obtained due to the limitation of cost and time. For this reason, we suggested the rehabilitation weighting model (RWM) to determine it objectively or systematically. Based on the determined amount of I/I for an individual pipe, we also suggested the rehabilitation priority model (RPM), which is equipped with genetic algorithm, to determine the optimal rehabilitation priority (ORP) for sub-areas in term of minimizing the amount of I/I occurring while the rehabilitation process is performed. The benefit obtained by implementing the ORP for rehabilitation of subareas is estimated by the only waste water treatment cost (WWTC) of I/I which 1726 J.H. Lee et al.occurs during the sewer rehabilitation period. A decision making support system which is consisted of the RWM and the RPM was applied to an urban drainage area. The results of the ORP were compared with those of a numerical weighting method (NWM) and the worst order which are other methods to determine the rehabilitation order of sub-areas in field. The ORP reduced the WWTC by 22% compared to the NWM and by 40% compared to the worst order.

Framework for Risk-Based Decision Support on Infiltration and Inflow to Wastewater Systems

“…Lee et al [34] presented a model aiming to facilitate decisions on which order the wastewater system in subareas should be rehabilitated to minimize I/I-water to the WWTP during the rehabilitation process. Based on detected defects on each pipe in the system, the volume of I/I-water in the subareas was estimated.…”

“…Evaluation of models based on framework. A: Sola et al [29], B: Davalos et al [30], C: Diogo et al [31], D: Moskwa et al [32], E: Vallin [33], F: Lee et al [34], G: King County [35], H: DeMonsabert and Thornton [36]. Among the models, only Model E uses a risk-based approach.…”

An Innovative Approach for Drainage Network Sizing

“…In other cases, the optimization procedures were oriented to solve more general problems. For instance, Lee et al [24] proposed a methodology for efficient rehabilitation of sewer systems; Chill and Mays [25] and Zhang et al [26] proposed different procedures to determine the optimal locations to place various types of developments in a watershed to reduce the negative impacts of urbanization on watershed stormwater systems, and then changes in flow rates and volume from natural to developed conditions; Oxley and Mays [27] proposed an optimization model, based upon the simulated annealing method, to optimize the size and location of detention basin systems including the outlet structures subject to design constraints. An interesting review of the optimal design procedures available for sewer networks has been made by Guo et al [28].…”

Downscale Methodology for Determining Priority Orders of the Sewer Rehabilitation

“…Based on defects (Chae and Abraham, 2001;Moselhi and Shehab-Eldeen, 2000;Wirahadikusumah et al, 1998) and I/I inspection results (Belhadj et al, 1995), many studies have focused on sewer rehabilitation (Berardi et al, 2009;Chung et al, 2001;Chughtai and Zayed, 2008;deMonsabert and Thornton, 1997;deMonsabert et al, 1999;Fenner and Sweeting, 1999;Georgiou and Tittlebaum, 2004;Hager, 2010;Korving and Noortwijk, 2008;Korving et al, 2009;Prigiobbe and Giulianelli, 2009;Reyna et al, 1994;Yang and Su, 2009). The integrated models that combine I/ I estimation and sewer rehabilitation were also developed (Alvisi and Franchini, 2009;Becker et al, 2009;Chung et al, 2008;Halfawy et al, 2008;Lee et al, 2009;Zhang, 2008) based on sewer defects and I/I inspection results. Several sewer overflow studies have been focused on evaluating the bottom elevation of baffle walls for combined sewer overflow detention (Write et al, 2010), and for treating wet weather sanitary sewer overflows' (SSOs) wastewater (Jing et al, 2011).…”