• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.420-424
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• 2005

K시 강변여과수 개발 지역에서 적정 채수량 산정 및 지표수 연계 특성을 파악하기 위한 적절한 현장 시험 세부계획 수립과 그 근거를 마련하였다. 일반적으로 단계양수시험을 통하여 적정 채수량 산정 후, 산정된 적정 채수량으로 장기양수 시험을 통하여 주변 수리권에 미치는 지하수위 변화와 강변여과수의 수질변화를 관찰하여 지표수와 연계한 변동특성을 파악하는 일련의 과정을 생각할 수 있다. 그러나 K시 강변여과수 개발 지역과 같은 연약 지반에서는 단계 양수시험시의 높은 양수량에 인한 지반 침하의 우려로 인해 이에 대한 공정의 변화가 불가피하였다. 따라서 현장 시험 공정 순서를 바꾸어서 장기 양수 시험 후 단계양수시험을 수행하는 새로운 대안을 모색하였고 이를 뒷받침 해주는 근거를 제시하고자 한다. 뿐만 아니라 단계양수시험의 단계별 적절한 양수시간을 합리적, 효율적으로 결정하여 경제적이면서 가급적 빠른 시간 내에 단계양수시험을 완료 가능하게 만들고, 가능한 한 더 오랜 기간동안 장기 양수 시험을 가능하게 함으로써 제한된 시간내에 많은 수리지질학 및 화학적인 정보를 얻을 수 있도록 하였다.

• Journal of Soil and Groundwater Environment
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• v.10 no.2
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• pp.59-65
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• 2005

Step-drawdown test has been generally conducted to evaluate productivity or efficiency of both aquifer and well. In general step-drawdown test, pumping with a low constant discharge rate is conducted in the first stage until the drawdown within the well stabilizes. And then the groundwater is pumped with a higher rate in the next step until the drawdown stabilizes once more. This process is repeated at least three times (steps), with the equal duration. In this paper we tried to review some critical problems related to the step-drawdown test, which were revealed in the process of field practices and analyses. The problems, referred in this paper are mainly associated with the incorrect conceptual approach for analysis and incomplete data collection in the field test.

• Journal of the Korean GEO-environmental Society
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• v.14 no.8
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• pp.11-21
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• 2013

In-situ test to find the change of $Fe^{2+}$ and $Mn^{2+}$ concentrations and ion contents in groundwater was conducted during two pumping tests at the riverbank filtration site, where is the riverine area of the Nakdong River in Changnyeong-Gun. Groundwater was sampled at one pumping well and 10 monitoring wells during a 5 steps drawdown pumping test with the rates from $500m^3/day$ to $900m^3/day$ and a constant pumping test with $800m^3/day$. The change in ion concentration of groundwater was more remarkable during a step drawdown pumping test than a constant pumping test. Especially, the decrease in $Fe^{2+}$ and $Mn^{2+}$ concentrations was distinct in a step drawdown pumping test and it happens predominantly along the direction that the radius of pumping influence was small due to a good aquifer connectivity to a pumping position. The precipitation and the oxidation of iron and manganese were caused by an air inflow and a disturbance in groundwater flow due to an abrupt change in pumping rate. The pumping rate and spatial distribution of an aquifer around a pumping well need to be considered as an important factor for the development of in-situ iron and manganese treatment technology.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.105-109
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• 2005

폐기물매립장에서 발생하는 침출수의 확산정도를 정량적으로 추정하기 위해 매립장 주변에 설치되어 있는 2개 지하수공(BWM-1, BWM-2)에서 단공주입양수 추적자시험이 실시되었다. 브롬(Br-) 이온이 추적자로 이용되었으며, 추적자시험은 주입단계, 체이서단계 및 양수단계의 과정으로 실시되었다. 시험대상 구간은 지표면하 $20{\sim}24m$에 해당하는 파쇄암반층이며, 주입율과 양수율은 추적자시험 이전에 실시되어진 양수시험 자료에 의해 산정되었다. BWM-1 지하수공의 단공주입양수 추적자시험에 의해 추정된 종분산지수는 공극율이 0.01, 0.05, 0.1 및 0.5인 경우에 각각 9.50, 4.25, 3.00, 1.34cm 이다. 시험대수층의 공극율은 대략 $0.05{\sim}0.20$의 범위이며, 따라서 종분산지수는 $2{\sim}4cm$인 것으로 추정된다. BWM-2 지하수공의 단공주입양수 추적자시험에 의해 추정된 종분산지수는 공극율 0.01, 0.05, 0.1 및 0.5인 경우에 각각 3.32, 1.49, 1.05, 0.47cm 이다. 시험대수층의 공극율은 대략 $0.05{\sim}0.20$의 범위이며, 따라서 종분산지수는 $1{\sim}2cm$인 것으로 추정된다. 폐기물매립장에서 침출수가 유출할 경우, BWM-2 지하수공 주변의 파쇄암반층이 BWM-1 지하수공 주변의 파쇄암반층보다 침출수 확산이 2배 정도 빠르게 발생할 것으로 추정되었다.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.17-23
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• 2002

Pumping tests were carried out from seven wells in fractured rocks. The time-drawdown data were obtained from pumping wells and corrected for the elapsed time of step drawdown test using Cooper-Jacob's method. A statistical method. the least square of error, was used to yield the coefficient of aquifer losses, the coefficient of well losses, and the power which indicates the severity of the turbulence. The values of the power range from 1.65 to 6.48. The well losses result mainly from turbulent flow caused by radial flow nearby pumping wells. The turbulent flow depends on Reynolds number. Since the hydraulic characteristics of fractured rocks control the fluid velocity, the value of the power is an important factor to understand the aquifer system of fractured rocks.

• The Journal of Engineering Geology
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• v.20 no.2
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• pp.127-136
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• 2010

Optimal pumping rate, well efficiency and radius of influence were estimated using field step-drawdown tests. According to the analysis results, optimal pumping rates were estimated as 9.37, 16.20 $m^3/day$ for KDPW 1 and 8.11, 14.10 $m^3/day$ for KDPW 2. The well efficiency was calculated as 72.02~90.73% for KDPW 1 while it was 70.62~88.52% for KDPW 2. In the meanwhile, the steady-state analysis yielded the radius of influence (ROI) of 3.50~31.92 m in case of pumping at KDPW 1 and the ROI of 0.14~37.43 m in case of pumping at KDPW 2. In addition, the transient analysis produced the ROI of 0.02~8.34 m for KDPW 1 pumping and the ROI of 0.24~9.68 m for KDPW 2 pumping. The methodology used in this study can be usefully applied in the pump and treat remediation design for contaminated groundwater.

• Journal of Soil and Groundwater Environment
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• v.12 no.3
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• pp.36-43
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• 2007

In the case of single well pumping tests the storativities are generally overestimated. To compensate these errors, the effective wellbore radius should be introduced as a distance to an imaginary observation well in the time-drawdown analysis. Effective wellbore radius can be calculated through step drawdown tests or using skin factor equation. But both are of trial-and-error methods guessing real storativity values and, therefor, are difficult to apply to the field conditions. An equation was developed to estimate effective wellbore radius from storativity values obtained from pumping well data. For this study, a total of 136 time-drawdown data set were used to derive the equation. The effective wellbore radius were estimated first by changing them till the storativity values obtained from the pumping-well data match the ones based on the observation-well data. Then the equation was regressed from the relation between effective wellbore radius and the storativity values obtained from the pumping-well data. It is believed that the equation would be useful in estimating effective wellbore radius from the single well tests.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.255-265
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• 2017

We have determined the optimal pumping rate of the PW-2 water well (depth=100 m) at Imgokri, Sangju City. Cutting analysis and geophysical logging data reveal water-producing horizons at 26.1-26.5, 28.0-30.0, 33, 58, and 71 m. For pumping rates of 40, 55, 70, 90, and $132m^3/d$ over 70 days, the estimated drawdown from the PW-2 well was 6.48, 11.56, 18.07, 28.99 and 60.26 m, respectively. During a constant-rate pumping test at a rate of $117m^3/d$, the cone of depression intersected an impermeable boundary after 120-150 min of pumping. Therefore, we consider the critical pumping rate for well PW-2 to be $90m^3/d$. After pumping at $90m^3/d$ for 70 days, the calculated drawdown was 28.82-31.27 m. We suggest an optimal pumping rate for well PW-2 of $70-90m^3/d$, as the optimal pumping rate should be similar to the critical pumping rate. Sharp increases in the slope of the time-drawdown relationship, dissolved oxygen concentrations, and oxidation-reduction potential during the constant-rate pumping test indicate the limited development of bedrock aquifers around PW-2.

• The Journal of Engineering Geology
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• v.20 no.2
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• pp.203-212
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• 2010

The aim in this study is used to develop the remediation technologies for contaminated ground water. Slug, single well pumping and step-drawdown tests have been used to obtain hydraulic parameter estimates in the field. Slug tests yield hydraulic conductivity values using the Bouwer and Rice and C-B-P analysis methods. The mean and median hydraulic conductivity values of Bouwer and Rice method are $4.48{\times}10^{-3}$ and $1.16{\times}10^{-3}cm/sec$, respectively. On the other hand, C-B-P method gave mean and median hydraulic conductivity values of $2.37{\times}10^{-3}$ and $7.09{\times}10^{-4}cm/sec$, respectively. These analyses show a trend for the Bouwer and Rice method to yield lower hydraulic conductivity values in low permeability zones of granite in the study area. Sing well pumping test data were calculated through type curve in GW7, GW12 and MW9 wells. It could be interpreted that the differences of hydraulic conductivity and transmissivity values between GW7 and GW12, MW9 is related with fault clays and fractures in the bedrock among the wells. Step-drawdown tests were carried out in the KDPW1 and KDPW2 wells. The hydraulic parameter of KDPW1 and KDPW2 showed very litter difference between the values. The study of hydraulic parameter estimates can be used to purify in contaminated groundwater.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.250-254
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• 2005

국내의 상수원수 확보는 대부분을 표류수에 의존하고 있으나, 표류수의 경우 수질오염의 증가와 돌발 수질 오염 사고에 대한 대응 등의 취약점을 가지고 있다. 이러한 문제점을 해결하기 위해 근본적으로 깨끗한 상수원수를 확보하기 다양한 방법이 모색되어지고 있다. 수량적으로 안정적이고, 수질적으로 안전한 상수원수 취득 방법으로 강변여과수, 지하댐, 인공함양기법 등이 실질적으로 계획되어 시행되어지고 있다. 특히 강변 충적층의 자연정화 기능을 이용한 강변여과수 개발은 지하수 개발과 달리 수량적으로 안정적이고, 수질적으로 안전한 강변여과수 개발 방안이 적극적으로 진행되고 있다. 낙동강 하류 지역인 함안군, 창원시, 김해시 등은 대부분 하천 표류수에 의존하였으나, 유역내 충적층 발달 지역이 분포해 있고, 하상경사, 하상계수 등의 하천공학적 측면에서 강변여과수 개발에 유리한 입지조건을 가지고 있어 강변여과수 개발이 진행되고 있다. 현재 창원시 대산면 일대에서 국내최초로 방사형집수정을 이용한 강변여과수 개발이 진행되고 있으며, 현재 방사형 취수정 1기가 시공 완료되어 시험 가동 중에 있다. 본 연구에서는 창원시 대산면 일대에서 진행되고 있는 방사형 집수정 설치에 따른 양수시험을 실시하여 양수량에 따른 수위하강 겋항 등을 분석하여 적정 산출량을 결정하였고, 계획단계에서 적정 산출량 예상시 사용한 경험식(Petrovic, Milojevic 경험식)의 적합성 여부에 중점을 두어 진행 되었다. 연구대상 지역인 창원시 대산면 일대는 지하수위가 하천수위보다 높은 이득하천의 형태로 건기시 하천특성을 뚜렷하며, 양수실험을 위한 대용량 양수펌프 설치, 유량검증을 위한 대형 웨어 설치, 수위변화 측정을 위한 디지털 수위계 등을 설치하여 실험을 수행하였다. 단계/장기양수시험을 통하여 양수량-수위하강 경향을 분석하여 방사형 집수정 1기의 적정 양수량은 약 $16,000m^3/day$로 예상하였으며, 계획 시 사용한 경험식(Milojevic)으로 산정된 산출예상량과 유사한 특성을 나타내었다.