• Journal of Korea Water Resources Association
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• v.41 no.2
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• pp.127-135
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• 2008

The objective of sewer rehabilitation is to improve its function while eliminating inflow/infiltration (I/I) and insufficient carrying capacity (ICC). Such rehabilitation efforts, however, have not been particularly successful due to a lack of sewer data and unsystematic field practices. The present study aimed to solve these problems by developing a decision making model consisting of two models: the rehabilitation weighting model (RWM) and the rehabilitation priority model (RPM). In RWM, the I/I of each pipe in a drainage district is estimated according to various defects, with each defect given an individual weighting factor using an analytic hierarchy process (AHP). RPM determines the optimal rehabilitation priority (ORP) using a genetic algorithm (GA). The developed models can be used to overcome the problems associated with unsystematic practices and, in practice, as a decision making tool for urban sewer system rehabilitation.

• Journal of Wetlands Research
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• v.20 no.3
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• pp.219-226
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• 2018

Interceptor sewer is installed underground near to the river side mostly ofstate-owned land and the management efficiency of public sewage disposal facilities is decreasing as too much infiltration/inflow(I/I) and river flow to interceptor sewer are caused by broken or deteriorated sewer. This also affects the sewer pipeline project and decreases its efficiency. Therefore, the aim of this study is to investigate interceptor sewer which has influence on the reduction of the project effect. The investigation were performed for three study areas. The study includes the investigation of current condition of interceptor sewer(sewer extension, pipe diameter, pipe type, installed year, installed locations, etc), investigation of inside of sewer by CCTV accompanied by pumping and dredging works where required, investigation of inside of manholes by eyes, calculation of pollutant load using the results of investigation of flow quantity and quality. Multipoint investigations were simultaneously performed for flow quantity at confluence area and other investigations were also performed for flow quantity and BOD for interceptor sewer and comparison of pollutant load, investigation of infiltration/inflow(I/I) caused by deterioration of interceptor sewer. As the result of the study, a main reason for reduced effect of sewer pipe improvement project was analyzed as the low-density sewage and I/I in public seweage treatment Facility due to deteriorated and unmanaged interceptor sewers.

• Economic and Environmental Geology
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• v.49 no.5
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• pp.361-370
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• 2016

It is well known that the inflow of rainwater and the infiltration of groundwater to sewerage (I/I) increase the sewage and burden sewage treatment plants and lower their treatment efficiency. Therefore, it is important to estimate the amount of I/I. In this study, well groundwaters, public water supplies (PWSs), and sewage and rainwater channels were investigated to check whether oxygen and deuterium isotopes could be used as a tool for I/I estimation. This study shows that the isotopic composition of PWS in Jeonju area is very consistent over time and distinctly lighter than the circulating local rainwater (CLR) because it is supplied from Yongdam Dam, which is located about 40 km inland to the east in the mountainous area. Considering the fact that sewage mostly originates from the PWS, we could calculate the amounts of CLR in the sewerage from a monitoring station using unaffected rainwater and tap water as mixing end members. The calculation revealed that the CLR fraction ranged from 50% to 90% depending on observation time. This is well supported by the dilute natures of the sewages at the station. The fraction of PWS in investigated well waters were about 46%, indicating that leaking of PWS is very serious and is an important groundwater source in the study area. Since the infiltration of such groundwater may not alter the isotopic composition of sewage significantly, the actual I/I would be much greater than the calculated ones.

• Journal of Environmental Science International
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• v.19 no.6
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• pp.747-753
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• 2010

It follows in quality and sewage exclusion method of the investigation objective sector and the Combined Sewer Overflows which is suitable in regional characteristics and the confluence area against the rainfall initially a flow and the medulla and measurement - it analyzes the initial rainfall outflow possibility control plan which is suitable in the domestic actual condition and it proposes the monitor ring plan for the long-term flow and pollution load data accumulation. From the research which it sees the Infiltration water/Influent water and CSOs investigation it passes by the phase of hazard chain and Namwon right time 4 it does not hold reverse under selecting, Measurement it used the hazard automatic flow joint seal Sigma 910 machine and in case 15 minute interval of the I/I, it measured a flow at case 5, 15 minute standing of the CSOs. The water quality investigation for the water leakage investigation of the I/I and the sewage from the point which is identical with flow measurement during on-the-spot inspection duration against 6 items which include the BOD sampling and an analysis, when the rainfall analysis for CSOs fundamental investigation analyzed against 18 items which include the BOD sampling. Consequently, for the optimum interpretation invasion water / inflow water of the this investigation area day average the lowest flow - water quality assessment veterinarian optimum interpretation hazard average per day - lowest flow - it averages a medulla evaluation law department one lowest flow evaluation technique and it selects, it presentation collectively from here it gets, position result with base flow analysis of invasion water / inflow water.

• Journal of Korea Water Resources Association
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• v.37 no.3
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• pp.195-206
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• 2004

One of the main factors which reduces the efficiency of a sewage treatment plant is the Inflow/Infiltration(Ⅰ/Ⅰ) in the sewer First we must calculate the quantity of Ⅰ/Ⅰ via the investigation of each sewer to establish the reduction plan of Ⅰ/Ⅰ. However, in Korea, we apply the results of a surveyed sample to the entire study area to establish the reduction plan of Ⅰ/Ⅰ. This methodology just considers the total Ⅰ/Ⅰ for the entire study area but it does not consider the quantity of Ⅰ/Ⅰ for the individual sewer systems. Therefore, we may need the model to consider the Ⅰ/Ⅰ in the individual sewer systems and we develop the model to calculate the Ⅰ/Ⅰ that happen in urban sewer systems. We estimate the Ⅰ/Ⅰ of individual systems by the developed model and the estimated Ⅰ/Ⅰ are utilized as the basic data for the establishment of Ⅰ/Ⅰ reduction plan. The observed Ⅰ/Ⅰ for the entire study area is distributed into the individual sewer systems according to their defect states. Here, the weights of defect elements are calculated using AHP(Analytic Hierarchy Process) and we perform the uncertainty analysis for considering the errors using MCS(Monte Carlo Simulation).

• Journal of Korean Society of Water and Wastewater
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• v.23 no.3
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• pp.287-293
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• 2009

The study involved the measurement of flowrate and BOD in the Yeoju area and analyzed annual sewerage data by the I/I analysis technique which is common in Korea. The results of this study are as follows. The I/I for the Y-1 site before maintenance and after the completion of the whole process was reduced from 62% to 16.1% respectively with respect to maximum sewage flow per day. The average quality of water increased. The study measured the Y-2 site from a point of time corresponding to an 80% process rate and its I/I rate went up a little from 8.5% to 11.5%. At the Y-3 site, the I/I rate went up a little from 11% to 13.8%, while little change was noted in the average water quality. At the Y-4 site, the I/I rate was reduced from 43% to 16.9% and its average water quality went up. At the Y-5 site, the I/I quantity went up a little however its average water quality also went up largely. Therefore, it was concluded that the Y-5 site showed great improvement due to the sewer pipe maintenance.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.2
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• pp.179-185
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• 2016

In this study, the RDII predictions were compared using two methodologies, i.e., the RTK-based and regression methods. Long-term (1/1/2011~12/31/2011) monitoring data, which consists of 10-min interval streamflow and the amount of precipitation, were collected at the domestic study area (1.36 km2 located in H county), and used for the construction of the RDII prediction models. The RTK method employs super position of tri-triangles, and each triangle (called, unit hydrograph) is defined by three parameters (i.e., R, T and K) determined/optimized using Genetic Algorithm (GA). In regression method, the MovingAverage (MA) filtering was used for data processing. Accuracies of RDII predictions from these two approaches were evaluated by comparing the root mean square error (RMSE) values from each model, in which the values were calculated to 320.613 (RTK method) and 420.653 (regression method), respectively. As a results, the RTK method was found to be more suitable for RDII prediction during extreme rainfall event, than the regression method.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.5
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• pp.119-128
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• 2008

Sewer rehabilitation is performed to improve the problem for urban drainage sewer system recently. However the data for the sewer system is not stored enough so that the sewer system is difficult to be managed systematically. In this study, a maintenance management system for urban drainage system is developed to store the data efficiently and manage the system systematically. In the developed system, a hydraulic and hydrologic analysis module is included to test the carrying capacity of a sewer pipe and estimate the amount of combined sewer overflows. The I/I and superannuation evaluation module is included in this system. The module distribute the total inflow/infiltration observed at the several sampling points in a drainage area to the individual pipes of the entire sewer system. Then the superannuation of a sewer pipe is evaluated according to the amount of I/I of the pipe. And in the developed system, the optimal rehabilitation priority module is included to determine the optimal priority and support the decision making for the sewer rehabilitation. The maintenance management system which is developed in this study is constructed by the association with the developed modules and the system is formed as graphical user interface system.

• Journal of Korean Society on Water Environment
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• v.32 no.4
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• pp.367-374
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• 2016

In this study, the RDII impact on sewer designing in the upstream monitoring area (A site) was considered. Based on the long-term (1/1/2011~12/31/2011) rainfall and flow data consisting of 10-min interval sampling in the nearby design area (B site), the maximum RDII/DWF ratio was selected. The sewer network system at B site was evaluated by the Manning equation. Scenario 1 considering the hourly maximum flow with respect to the flow velocity showed that none of the sewer pipes satisfied the minimum flow velocity condition (0.6 m/s), and 40 pipes did not achieve half of the velocity condition. In scenario 2 considering I/I, 1 the pipes satisfied 0.6 m/s, and 35 pipes showed 0.3 m/s. Scenario 3 reflected the effect of RDII. Velocities in 26 pipes were less than 0.3 m/s, and 4 pipes satisfied the velocity condition. With respect to the allowance rate, 17 pipes were shown to have more than 99%, and none of the pipes satisfied less than 95% of the allowance rate in scenario 1. In scenario 2, 17 Ed: Per the Table pipes showed more than 99% and one pipe showed less than 95%. In scenario 3, 16 pipes showed more than 99% of the allowance rate, and 19 pipes showed less than 95%. Based on these results, it is predicted that deposition would occur due to the slow flow velocity; however, capacity would not be a problem.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.229-235
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• 2011

In order to manage a sewer system effectively, flow conditions such as flux, water quality, Infiltration and Inflow (I/I), Combined Sewer Overflows (CSOs), etc need to be monitored on a regular base. Therefore, in sewer networks, a monitoring is so important to prevent the river disaster. Monitoring all nodes of an entire sewer system is not necessary and cost-prohibitive. Water quality monitoring points that can represent a sewer system should be selected in a economical manner. There is no a standard for the selection of monitoring points and the quantitative analysis of the observed data has not been applied in sewer system. In this study, the entropy method was applied for a sewer network to evaluate and determine the optimal water quality monitoring points using genetic algorithm. The entropy method allows to analyze the observed data for the pattern and magnitude of temporal water quality change. Since water quality measurement usually accompanies with flow measurement, a set of installation locations of flowmeters was chosen as decision variables in this study.