• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1133-1143
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• 2016

The purpose of this study is to improve project performance analysis indicators for BTL sewer rehabilitation projects. Among the assessment indicators for BTL sewer rehabilitation projects, an infiltration assessment indicator is given a high score of 17.5 points as a single assessment item. This infiltration assessment indicator is assessed focusing on the amount of infiltration, and presently calculated according to 'Nighttime Domestic Flow Evaluation' method. However, this assessment indicator's failure to reflect the geological features of Jeju region is emerging as a problem in the operational stage. Thus, this study intended to compare and analyze the calculation result depending on the assessment indicators and the actual amount of infiltration, centering on Jeju region. To this end, this study analyzed the amount of infiltration in five areas of Jeju Province calculated according to 'Nighttime Domestic Flow Evaluation' method. Also, a complete enumeration survey was carried out about the conditions for actual infiltration occurrence. According to the results of this survey, ground water level is distributed lower than the level of sewer pipes. The results of a sewer pipe function test show there was no infiltration occurrence caused by sewer pipe defect. So, it is concluded that 'Nighttime Domestic Flow Evaluation' method, which is utilized for the current assessment indicator, is not appropriate to apply to Jeju region, and it is thought that there is a need to establish infiltration criteria specialized for Jeju region.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1295-1299
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• 2004

노후된 하수도 관망에서 발생하는 불명수(Inflow/Infiltration)량을 측정하기 위하여 수문학적 타당성을 비롯한 다양한 인자를 고려하여 많은 방법들이 개발되었다. 현행 실무에서는 물사용평가방법, 일 최대-최소 유량평가법, 일최대 유량평가법, 야간생활하수 평가법 등으로 산정하고 있으나 각 산정값들간의 차이가 매우 크면, 각 방법별 산정된 불명수의 평균값을 채택하는 현행 기준은 그 근거가 명확하지 않고 오차값이 신뢰할 수 있는 범위를 벗어난다. 본 연구에서 제안한 방법은 도시유출 해석 프로그램인 SWMM(Storm Water Management model)을 이용하여 모의유출량을 산정한 다음, 이를 관측유량과 비교하여 그 차이를 불명수량으로 산정하는 방법이다.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.3
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• pp.191-200
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• 2020

This study is to improve the efficiency of BTL (Build Transfer Lease) project operation by comparing the infiltration rate based on the data of 5 years of infiltration of the separate sewer system and combined sewer system. In the survey site, the separate sewer system area consists of eight flowmeters in seven treatment basins, and the combined sewer system area consists of eight flowmeters in five treatment basins. The infillration rate was analyzed by night-time domestic flow evaluation method, and the average infiltration rates of the separate sewer system and combined sewer system were 13% and 16%, respectively. Combined sewer system was about 1.3 times higher than the separate sewer system. The average BOD of separate sewer system was 233 mg/L, which was about 2.4 times higher than the combined sewer system was 107 mg/L. In the comparison of the average pipe diameter-length infiltration of separate sewer system and combined sewer system, the separate sewer system and the combined sewer system were about 0.150 ㎥/d/mm/km and about 0.109 ㎥/d/mm/km, respectively. The floating population in mixed residential and commercial areas has been identified as the cause. Therefore, we propose a method to calculate the infiltration rate in consideration of the margin ratio in the area where the night active population is concentrated.