• 상하수도학회지
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• 제28권1호
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• pp.33-45
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• 2014

In this study, current sewer infiltration/Inflow(I/I) computation and application method was examined about improvement and adequacy relating to the main issues raised by the field for practitioners. The results of review about infiltration calculation method were considered to be in need of improvement at 'standards of minimum sewage calculation'. Furthermore, the results of review about I/I application method were considered to be in need of improvement at 'standards of seasonal infiltration application' and 'the relative decrease in the Annual evaluation standards'. In addition, annual I/I analysis at JC County for the four years(2009~2012) in respect of operation flow and rainfall data was conducted. The result of annual infiltration analysis, compared average daily sewage generated average infiltration rate was found in 21.95 %, infiltration by unit was found in $0.31m^3/day/cm/km$ and $0.12m^3/day/day$, respectively. The result of annual inflow analysis, average rainfall - Inflow equations was found $y=5.499{\times}$($R^2$ 0.793), and the average Inflow quantity by sewer extension was predicted to $0.66m^3/mm-km$.

• 상하수도학회지
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• 제34권3호
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• pp.211-220
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• 2020

When domestic sewage and rainwater runoff are discharged into a single sewer pipe, it is called a "combined sewer system." The sewage design standards in Korea specify the flow velocity based only on the volume of rainfall; therefore, sedimentation occurs on non-rainy days owing to the reduced flow rate and velocity. This sedimentation reduces the discharge capacity, causes unpleasant odors, and exacerbates the problem of combined sewer overflow concentration. To address this problem, the amount of sewage on non-rainy days, not just the volume of rainfall, should also be considered. There are various theories on sedimentation in sewer movement. This study introduces a self-cleansing velocity based on tractive force theory. By applying a self-cleansing velocity equivalent to the critical shear stress of a sand particle, sedimentation can be reduced on non-rainy days. The amount of sewage changes according to the water use pattern of citizens. The design hourly maximum wastewater flow was considered as a representative value, and the velocity of this flow should be more than the self-cleansing velocity. This design method requires a steeper gradient than existing design criteria. Therefore, the existing sewer pipelines need to be improved and repaired accordingly. In this study, five types of improvement and repair methods that can maximize the use of existing pipelines and minimize the depth of excavation are proposed. The key technologies utilized are trenchless sewer rehabilitation and complex cross-section pipes. Trenchless sewer rehabilitation is a popular sewage repair method. However, it is complex because the cross-section pipes do not have a universal design and require continuous research and development. In an old metropolis with a combined sewer system, it is difficult to carry out excavation work; hence, the methods presented in this study may be useful in the future.

• 상하수도학회지
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• 제25권2호
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• pp.185-192
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• 2011

Pearson's correlation was used to determine relations between infiltration and affecting factors using flow monitoring data measured in 24 areas with different characteristics. Factors showed relatively high correlations than others were indexed to determine infiltration rates of the study area. Among 8 factors(service area, sewer length, sewer diameter, multiplier of sewer length and diameter, number of manholes, population, number of properties, number of households) tested, the multiplier of sewer length and diameter, the number of population and the number of household in each service area indicated higher correlation coefficient(>0.8) than others. The goodness of fitness of linear regressions between infiltration and the factors followed the order: sewer length and diameter(0.68)> population(0.65)> number of household(0.60). Infiltration rates calculated by the multiplier of sewer length and diameter, the number of population and the number of household in each service area were 0.046~1.0396 $m^{3}/d{\cdot}mm-km$, 0.0917~1.7355 $m^{3}/capita{\cdot}d$, 0.196~4.529 $m^{3}/household {\cdot}d$ respectively. After sewerage rehabilitation work of the area, the infiltration rates calculated by above factors with high correlations are expected to be used for comparing effectiveness of the work once they are estimated under the same flow measuring conditions.

• 상하수도학회지
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• 제34권4호
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• pp.251-258
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• 2020

Sewer deterioration models are needed to forecast the remaining life expectancy of sewer networks by assessing their conditions. In this study, the serious defect (or condition state 3) occurrence probability, at which sewer rehabilitation program should be implemented, was evaluated using four probability distribution functions such as normal, lognormal, exponential, and Weibull distribution. A sample of 252 km of CCTV-inspected sewer pipe data in city Z was collected in the first place. Then the effective data (284 sewer sections of 8.15 km) with reliable information were extracted and classified into 3 groups considering the sub-catchment area, sewer material, and sewer pipe size. Anderson-Darling test was conducted to select the most fitted probability distribution of sewer defect occurrence as Weibull distribution. The shape parameters (β) and scale parameters (η) of Weibull distribution were estimated from the data set of 3 classified groups, including standard errors, 95% confidence intervals, and log-likelihood values. The plot of probability density function and cumulative distribution function were obtained using the estimated parameter values, which could be used to indicate the quantitative level of risk on occurrence of CS3. It was estimated that sewer data group 1, group 2, and group 3 has CS3 occurrence probability exceeding 50% at 13th-year, 11th-year, and 16th-year after the installation, respectively. For every data groups, the time exceeding the CS3 occurrence probability of 90% was also predicted to be 27th- to 30th-year after the installation.

• 물과 미래
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• 제42권12호
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• pp.65-69
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• 2009

• 한국상하수도협회지
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• 통권4호
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• pp.28-37
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• 2003

• 상하수도학회지
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• 제25권2호
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• pp.213-221
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• 2011

The purpose of sewer system is to separate rain water from sewage water. Through this, it is possible to prevent the flood and preserve public water territory. For the past few years, many problems of the sewer system have been solved by the execution of sewer rehabilitation project. However, they still exist in sewer system caused by I/I, which are divided into infiltration and inflow. Infiltration means the rain water and underground water that infiltrate through breakage point on pipes, inflow means the water that flows in through misconnection on pipes. This study shows how the I/I calculation has changed according to the new standardized manual and identifies the I/I difference between the new calculation and the existing one. Through the analysis on the two calculation methods we examined the appropriacy of the new method by comparing it to the old one. The result points out that the new standardized manual is more appropriate than the old in aspect of objectivity and reproducibility(establish standardization), rationality(alteration of inflow unit).

• 대한토목학회논문집
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• 제35권1호
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• pp.217-227
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• 2015

본 연구는 건설투자 GDP (Gross Domestic Product) 디플레이터 방식의 물가조정이 이루어진 제주특별자치도 내 하수관거정비 BTL(Build-Transfer-Lease)사업에 대하여 물가변동률 적용에 문제점을 파악하기 위하여 실시되었다. 분석 결과, GDP 디플레이터 방식의 기준지수는 고정값을 사용하며 매분기별 물가변동률이 반영되기 때문에 지수조정률 방식보다 물가변동률이 높게 나타나는 것으로 조사되었다. 그러나 GDP 디플레이터 지수가 총사업비에 일괄적으로 적용되기 때문에 현실적인 물가를 반영하지 못함으로써 정확도가 떨어지는 단점이 있는 것으로 조사되었다. 또한 GDP 디플레이터 방식의 기준지수가 고정값을 사용하기 때문에 기준이 되는 시점(정부고시일)이 물가조정에 매우 크게 영향을 미치는 것으로 조사되었다.

• 한국콘텐츠학회논문지
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• 제12권8호
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• pp.388-398
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• 2012

본 연구에서는 도시 하수관거시스템의 침수위험순위 평가를 위하여 엔트로피(Entropy) 기법 및 다기준 의사결정기법의 하나인 프로메티(Preference Ranking Organization METHod for Enrichment Evaluations, PROMETHEE)를 적용하였다. 엔트로피와 프로메티를 이용한 침수위험순위 산정에 있어서 평가 대상이 되는 항목들은 두 가지의 접근방식으로 선정되었다. 먼저 침수발생 및 피해 규모에 영향을 미치는 인자로 지형 환경적 요인으로써 유역의 평균고도, 평균경사, 유역폭, 인구수 및 관밀도를 선정하였다. 또한 각 시스템별 침수가 가장 크게 발생하는 초과강우사상을 선정 및 적용하여 시스템내 월류발생량 및 발생지점 두 가지를 이용한 치수안전성 지수를 추가적으로 고려하였다. 본 논문에서 적용된 엔트로피기법과 프로메티에 의한 도시 하수관거시스템 침수위험순위 평가는 추후 하수관거 정비사업의 계획 및 추진에 있어서 각 시스템별 위험도에 따른 개량우선순위 결정 및 평가지표로서 활용될 수 있을 것이다.

• 한국습지학회지
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• 제15권4호
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• pp.461-469
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• 2013

하수관거정비 임대형민자사업(BTL)은 많은 예산이 투입되어 전국적으로 시행되었으나 사업시행 후 나타난 사업효과에 대한 종합적인 검토는 미흡한 실정이다. 또한, 일부 사업의 경우 준공 후 측정된 유량 Data의 신뢰성 문제 및 과다한 I/I(침입수/유입수) 발생량 등으로 인해 사업의 성과에 대한 문제제기와 I/I지표의 운영평가 적용과 관련한 논란이 지속적으로 제기되고 있는 실정이다. 따라서 본 연구에서는 '05년 JC군 하수관거정비 임대형민자사업(BTL) 등 시설물 준공 후 운영성과평가가 진행 중인 연구대상 사업 15개 사업에 대하여 사업효과분석, 유량계 설치 실태 분석 및 개선방안 등을 검토하였다. 검토결과 하수관거정비 임대형민자사업(BTL) 시행 후 하수처리장 운영효율 개선, 하수관거 침입수 발생비율 저하, 주변하천 수질개선 등의 효과가 나타난 것으로 분석되었으며, 유량계 설치 및 운영 현황 조사결과 나타난 주요 문제점에 대해서는 본 연구의 개선방안 적용시 보다 신뢰성 있는 유량 데이터가 확보될 수 있는 것으로 검토되었다.