• Journal of Environmental Science International
• /
• v.28 no.10
• /
• pp.887-898
• /
• 2019

Rehabilitation work is required to increase well productivity, which decreases with the elapsed time of pumping owing to the clogging of the water well. Clogging causes not only a reduction in the well productivity but also a deterioration of the water quality. For unclogging and rehabilitating wells, several techniques are used such as brushing, air surging, surge blocks, and gas impulse. In this study, the high-pressure air impulse technique, which effectively and economically rehabilitates wells, was applied to a riverbank filtration site in Korea for the same objective. At most of the wells, the hydraulic parameters (transmissivity, storage coefficient, and specific capacity) were increased by the application of the high-pressure air impulse technique. The well loss change values also indicate an increase in the hydraulic parameters by the air impulse implementation. Thus, the high-pressure air impulse technique can be efficiently and economically applied to water and riverbank filtration wells for rehabilitating the decreased productivity.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.729-736
• /
• 2009

Several well resistance effects induced by bending, confining stress, temperature, bubbles, and apparent opening size have been considered and researched for the reasonable PBD design. The effect of apparent opening size(AOS), however, was not extensively studied and the clogging effect by AOS was not clearly researched. In this paper, the slurry consolidation test which 4 types of PBD are installed in large slurry consolidometer($H{\times}D$, $2.0m{\times}1.2m$) is performed to investigate the clogging effect by filter's AOS. The results show that the internal clogging is observed all types of PBD, and a quantity of inflowed soil particles are increased at the lower part of PBD and the kink zone. In addition, the internal clogging phenomenon does not relate with the shape and size of PBD. In filter's AOS test, it was easily observed that soil particles bigger than AOS of tested filter passed PBD filter by SEM. This paper demonstrates that the reduction of discharge capability may be accelerated by internal clogging at the kink zone.

• Journal of Soil and Groundwater Environment
• /
• v.15 no.1
• /
• pp.39-49
• /
• 2010

Drilling at unconsolidated layer can make the aquifer disturbed and reduce a productivity of groundwater well. Surge block and air surging were applied to a pumping well located in Jeungsan-ri, Changnyung-gun, to improve a well efficiency by removing clogging and fine-grained slime. Two experimental log-linear equations, $y_1=-0.1769\;ln(x_1)+0.4960$ and $y_2=-84.3358\;ln(x_2)+512.8162$, were proposed in this site, in which $x_1$ and $x_2$ are the number of surging event, $y_1$ is the amount of slime, and $y_2$ is a recovery time of groundwater level after air surging. Well loss exponent (P) decreased after surging, from 3.422 to 1.439, and the groundwater inflow from aquifer happened in all directions around a well with gradually increasing the homogeneity in a local aquifer's hydraulic property. It was revealed that long-term well development should be done in the pumping well which is located in unconsolidated sediments to increase a well productivity.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2001.03a
• /
• pp.563-570
• /
• 2001

In this study, the charactersistics of horizontal drains used to stabilize the dredged fill are investigated experimentally by doing tensile strength test, discharge capacity test, and filter clogging test. The types of the drains selected for the study are filament type (Tyre-E), embossed type(Type-P) and heat bonded cubic type with the thickness 10mm(Type-010) and 5mm(Type-05). The results of tensile strength and discharge capacity test show that the performance of drain Type-O10 was better than the other drains. This is caused by the fact that the lattice shape core of drain Type-O10 has strong rigidity and minimizes the loss of the sectional area of discharge with increased confining pressure. Analyzing the compatibility of filters by the results of the strength characteristics test and clogging test, the filter of filament type drain produced with polyester clothed polyamide performed well.

• Journal of Korean Society on Water Environment
• /
• v.32 no.1
• /
• pp.36-45
• /
• 2016

Sand filters are widely used in infiltration systems to manage polluted urban runoff. Clogging, which is mainly caused by the deposition of sediments on the filter media, reduces the filter system's infiltration capacity, which further limits its lifespan and function. The physical, chemical and biological clogging characteristics of sand filter, therefore, need to be known for effective design and maintenance. Physical clogging behavior and variations in the characteristics of sand filters according to different media depths are examined in this paper. The variations were observed from laboratory column infiltration tests conducted in a vertical flow and fluctuating head condition. It can be seen that an increase in filter media depth results in a high sediment removal performance; however, it leads to a shorter lifespan due to clogging. In the choice of filter media depth to be used in field applications, therefore, the purpose of facilities as well as maintenance costs need to be considered. At all filter media depth configurations, premature clogging occurred because sediments of 100~250 μm clogged the top 15% of filter media depth. Thus, scrapping the top 15% of filter media may be suggested as the first operational maintenance process for the infiltration system.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.03a
• /
• pp.267-278
• /
• 2010

To improve the grout penetration characteristics, vibration method was adopted in this study. The grout material perturbed by cyclic vibration is injected into the ground. By applying the vibrating flow system, cement particles will become less adhesive and the clogging tendency will be decreased. A series of pilot-scale chamber tests were performed to verify the enhancement of the groutability by applying the vibratory grout injection; assessment on change of the lumped parameter $\theta$ which represents a barometer of clogging phenomenon was made. Moreover, the effect of vibratory grout injection through the joint was also investigated using artificially made rock joints. Experimental results as well as analytical results show that the grout penetration depth can be substantially improved by vibration grouting. Moreover, it was found that enhancement of the permeation grouting due to vibratory injection is more dominant at low grouting pressure of less than 400kPa.

• Journal of Korean Society on Water Environment
• /
• v.33 no.5
• /
• pp.572-579
• /
• 2017

Increased impervious surface caused by rapid urbanization serves to produce the discharge of non-point source pollutants such as total suspended solid (TSS). There exist various methods of removing TSS, including a filtration process using granular media (a well-known method to be practically used after the consideration of removal efficiency, clogging, and backwashing efficiency). To determine the TSS removal capability of the filter, we initially performed lab-scale experiments which assessed flow rates, influent concentrations, permeability co-efficients, the particular shapes of suspended solids and potential clogging, and also evaluated TSS removal efficiency when applied to filtration facility in a pilot-scale. In low filtration flux condition, the removal efficiency of suspended solids was more than 95 %, while decreased to 83% in high filtration flux. Regarding the clogging aspect of the experiment, total cumulative solids were loaded up to $19.15kg/m^2$, and TSS removal efficiency was noted to commence to decrease when the loaded solids exceeded $9.0kg/m^2$. It was also noted, however, that superior efficiency was maintained for six hours. In addition, for pilot-scale experiment, the removal efficiency was still high enough (83.4 %) for the solid concentration of 140 ~ 343 mg SS/L and after backwashing, head loss was recovered to 92 ~ 95 % during two hour filtration. With these results, It was confirmed that lifetime of the filter applied to the test was prolonged due to the high treatment efficiency and good backwashing efficiency for the cumulative solids load.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2002.04a
• /
• pp.263-266
• /
• 2002

The purpose of this study is to clarify the reasons of pipe corrosion and well clogging which are taken place in long term bank filtering and to establish countermeasure of them in the alluvium of Goryeong Gun, Dasan Myeon, Nakdong River It is believed that the scale inside the pipe is not caused by only iron hydroxides but compounds consisted with some carbonate and silicate minerals. For the removal of the scales, it is desirable to loosen the bonds of the scale itself by dissolving the carbonate and silicate minerals after detailed study of the scale compounds.

• The Journal of Engineering Geology
• /
• v.22 no.1
• /
• pp.67-81
• /
• 2012

The physical, chemical, and biological properties of clogging materials formed within groundwater wells in the Mt. Geumjeong area, Busan, Korea, were characterized. The particle size distribution (PSD) of clogging materials was measured by a laser analyzer. XRD, SEM, and TEM analyses were performed to obtain mineralogical information on the clogging materials, with an emphasis on identifying and characterizing the mineral species. In most cases, PSD data exhibited an near log-normal distribution; however, variations in frequency distribution were found in some intervals (bi-or trimodal distributions), raising the possibility that particles originated from several sources or were formed at different times. XRD data revealed that the clogging materials were mainly amorphous ironhydroxides such as goethite, ferrihydrite, and lapidocrocite, with lesser amounts of Fe, Mn, and Zn metals and silicates such as quartz, feldspar, micas, and smectite. Reddish brown material was amorphous hydrous ferriciron (HFO), and dark red and dark black materials were Fe, Mn-hydroxides. Greyish white and pale brown materials consisted of silicates. SEM observations indicated that the clogging materials were mainly HFO associated with iron bacteria such as Gallionella and Leptothrix, with small amounts of rock fragments. In TEM analysis, disseminated iron particles were commonly observed in the cell and sheath of iron bacteria, indicating that iron was precipitated in close association with the metabolism of bacterial activity. Rock-forming minerals such as quartz, feldspar, and micas were primarily derived from soils or granite aquifers, which are widely distributed in the study area. The results indicate the importance of elucidating the formation mechanisms of clogging materials to ensure sustainable well capacity.

• The Journal of Engineering Geology
• /
• v.26 no.3
• /
• pp.331-337
• /
• 2016

Radial collector wells (RCWs) have been managed by Korea Rural Community Corporation (KRC) since 1983, installing 98 wells for agriculture in rural area over the country. Among them, 20 wells were installed upstream of 5 subsurface dams and the remaining were installed regardless of the subsurface dam. Most of RCWs have been developed in 1980s and 1990s, and 83 wells have been passed more than 20 years after construction. The number of horizontal arms for RCWs varies from 9 to 28, with length and diameter being 10~30 m and 65 mm, respectively. The central caisson with an inner diameter of 3.5 m was commonly constructed to a depth of 10 m. The maximum pumping rates in RCWs, which are located at distances of 10 to 1,200 m from the river, are 2,000~10,000 m³/day. RCW has a fundamental problem that reduced pumping capacity and degraded well efficiency, due to the physical and chemical clogging. From the feasibility test for improving RCW performance, specific capacity increased to 67% after rehabilitation. TV logging for RCW horizontal arm shows that near the caisson is more severe clogging. From the results of this study, KRC has established the guidebook for monitoring and improving well efficiency through physical/chemical treatment, well logging, and hydraulic tests and managed RCWs periodically with its rehabilitation methods.