Attenuation of River Contaminant using River Bank Infiltration in Jenderam Hilir, Dengkil, Selangor

Bank infiltration (BI) refers to the process of surface water seeping from the bank or bed of a river to the groundwater production wells. During the water’s passage through the ground, its quality changes due to microbial, chemical and physical processes, and due to mixing with groundwater in the aquifer. The BI study in Jenderam Hilir, Selangor is a pilot project to develop a better and sustainable source of water, and will provide a good platform to introduce this method in Malaysia. BI has been successfully implemented in many Asian and European countries. This site was chosen due to the high water demand in the area and groundwater is seen as one of the source with very high potential to be developed as supplementary source to meet the high public water supply demand. The objective of this study is to determine the effectiveness of BI and improving the quality of river water, and to determine the effective rate of water extraction from the alluvium in the study area. Twenty five (25) monitoring wells and 2 test wells were constructed at the study site and pumping tests have been carried on these two test wells. The pumping tests at the 2 test wells indicated that DW1 and DW2 were able to produce more than 15.9 m3/hr (0.3816 MLD) and 128m3/hr (3.072 MLD) respectively during the duration of 72 hours pumping tests with drawdown for DW1 was 4.17 m and DW2 was 2.63 m. The distance between the river and the test well is more than 18 m and the shortest travel time is 10 days. The river water was filtered through a 16 m thick silty sand for DW1 and 13 m thick gravelly sand for DW2. Both wells are located in confined aquifer adjacent to the Sungai Langat. Water quality analyses carried out for water from the Sungai Langat and groundwater from the wells showed decreased in turbidity, nitrate, aluminium and sulphate in groundwater which were very high in the Sungai Langat. Microorganism counting (E. coli, total coliform, Cryptosporidium and Giardia) was also carried out. Results of sampling from the 2 test wells confirmed that the microorganism counts were significantly reduced during the passage in BI which is capable to achieve more than 99.9 % removal of E. coli, total coliform and Giardia. The study on the effectiveness of BI method is a proactive effort of NAHRIM to improve surface water quality as a source for domestic water of the modern urbanised area

Modelling the effect of hydraulic conductivity on one dimensional contaminant transport in RBF system

Riverbank filtration (RBF) system is a surface water technology that is based on the natural treatment of filtration instead of the use of chemicals, to pretreat surface water and provides public water supplies. Hydraulic conductivity value is one of the significant factors affecting the water quality in RBF systems. In this article, an analytical modelling is developed to investigate the effect of this parameter on one dimensional contaminant transport in RBF system. The model is solved by using Green’s function approach. The model is applied for the first RBF system conducted in Malaysia. Generally, the results show that increasing the hydraulic conductivity value lead to an increase in contaminant concentration in pumping well area

Groundwater and surface-water utilisation using a bank infiltration technique in Malaysia

Bank infiltration (BI) is one of the solutions to providing raw water for public supply in tropical countries. This study in Malaysia explores the use of BI to supplement a polluted surface-water resource with groundwater. Three major factors were investigated: (1) contribution of surface water through BI to the resulting abstraction, (2) input of local groundwater, and (3) water-quality characteristics of the resulting water supply. A geophysical method was employed to define the subsurface geology and hydrogeology, and isotope techniques were performed to identify the source of groundwater recharge and the interaction between surface water and groundwater. The physicochemical and microbiological parameters of the local surface-water bodies and groundwater were analyzed before and during water abstraction. Extracted water revealed a 5–98 % decrease in turbidity, as well as reductions in HCO3 −, Cl−, SO4 2−, NO3 −, Ca2+, Al3+ and As concentrations compared with those of Langat River water. In addition, amounts of E. coli, total coliform and Giardia were significantly reduced (99.9 %). However, water samples from test wells during pumping showed high concentrations of Fe2+ and Mn2+. Pumping test results indicate that the two wells used in the study were able to sustain yields

Particle tracking analysis of river-aquifer interaction via bank infiltration techniques

Induced bank infiltration (BI) is commonly implemented in other countries, but remains new and unexplored in Malaysia. Increasing river pollution could affect drinking water resources. Given the threat of pollution to raw water sources, applying induced BI to sustain water management is essential. This paper presents a case study of the BI method, which evaluates the effects of groundwater pumping and BI operation on the installation of wells as well as determines the effect of pumping rate on flow paths, travel time, the size of the pumping and capture zone delineation, and groundwater mixing in a pumping well in Jenderam Hilir, Malaysia. The proposed method performs infiltration safely and achieves the ideal pumping rate. Numerical modeling packages, MODFLOW and MODPATH (particle tracking) were used. Results indicate that the migration of river water into the aquifer is generally slow and depends on the pumping rate and distance from well to the river. Most water arrives at the well by the end of a pumping period of 1–5 days at 3,072 m3/day for test wells DW1 and DW2, and during simultaneous pumping for DW2 and PW1 for a well located 36 and 18 m, respectively, from the river. During the 9.7-day pumping period, 33 % of the water pumped from the DW1 well was river water, and 38 % from DW2 throughout 4.6 days was river water. The models provide necessary information for water operators in the design and construction of pumping and sampling schedules of BI practices

Conjunctive use of surface water and groundwater via the bank infiltration method

The bank infiltration (BI) technique may be a viable option if the local climate, hydrological, and geological conditions are conducive. This study was specifically conducted to explore the possibility of using BI to source the polluted surface water in conjunction with groundwater. Three major factors were considered for evaluation: (1) investigation on the contribution of surface water through BI, (2) input of local groundwater, and (3) water quality characteristics of water supply. Initially, the geophysical method was employed to define the subsurface geology and hydrogeology, and isotope techniques were performed to identify the source of groundwater recharge and interaction between surface water and groundwater. The physicochemical and microbiological parameters of the local surface water bodies and groundwater were analyzed before and during water abstraction. Extracted water revealed a 5 %–98 % decrease in turbidity, as well as HCO3 +, SO4 −, NO3 −, Al, As, and Ca concentration reduction compared with those of Langat river water. However, water samples from test wells during pumping show high concentrations of Fe2+ and Mn2+. In addition, amounts of Escherichia coli, total coliform, and Giardia were significantly reduced (99.9 %). Pumping test results indicate that the two wells (DW1 and DW2) were able to sustain yields

Using particle tracking as a tool sustainable bank infiltration techniques: a case study in an alluvial area

This study was inspired by the Klang Valley water crisis, for which bank infiltration (BI) is considered a potential solution. This paper presents a case study of the BI techniques, which evaluates the effects of groundwater pumping and BI operation on the installation of wells. This study also determines the effect of pumping rate on flow paths, travel time, the size of the pumping and capture zone delineation, and groundwater mixing in a pumping well in Jenderam Hilir, Malaysia. The proposed method performs infiltration safely and achieves the ideal pumping rate. Numerical modeling packages, MODFLOW and MODPATH (particle tracking) were used. Results indicate that the migration of river water into the aquifer is generally slow and depends on the pumping rate and distance from well to the river. Most water arrives at the well by the end of a pumping period of 1 to 5 days at 3,072 m3/day for test wells DW1 and DW2, and during simultaneous pumping for DW2 and PW1 for a well located 36 and 18 m, respectively, from the river. During the 9.7-day pumping period, 33 % of the water pumped from the DW1 well was river water, and 38 % of the water pumped from DW2 throughout 4.6 days was river water

Hydrogeochemistry and groundwater quality assessment of the multilayered aquifer in Lower Kelantan Basin, Kelantan, Malaysia

Continual expansion of population density, urbanization, agriculture, and industry in most parts of the world has increased the generation of pollution, which contributes to the deterioration of surface water quality. This causes the dependence on groundwater sources for their daily needs to accumulate day by day, which raises concerns about their quality and hydrogeochemistry. This study was carried out to increase understanding of the geological setup and assess the groundwater hydrogeochemical characteristics of the multilayered aquifers in Lower Kelantan Basin. Based on lithological data correlation of exploration wells, the study area can be divided into three main aquifers: shallow, intermediate and deep aquifers. From these three aquifers, 101 groundwater samples were collected and analyzed for various parameters. The results showed that pH values in the shallow, intermediate and deep aquifers were generally acidic to slightly alkaline. The sequences of major cations and anions were Na+ > Ca2+ > Mg2+ > K+ and HCO3− > Cl− > SO42− > CO32−, respectively. In the intermediate aquifer, the influence of ancient seawater was the primary factor that contributed to the elevated values of electrical conductivity (EC), Cl− and total dissolved solids (TDS). The main facies in the shallow aquifer were Ca–HCO3 and Na–HCO3 water types. The water types were dominated by Na–Cl and Na–HCO3 in the intermediate aquifer and by Na–HCO3 in the deep aquifer. The Gibbs diagram reveals that the majority of groundwater samples belonged to the deep aquifer and fell in the rock dominance zone. Shallow aquifer samples mostly fell in the rainfall zone, suggesting that this aquifer is affected by anthropogenic activities. In contrast, the results suggest that the deep aquifer is heavily influenced by natural processes

Evaluating the potential of bank infiltration as a source of water supply in Jenderam Hilir, Selangor, Malaysia

This study was inspired by the Klang Valley water crisis, for which Bank Infiltration (BI) was considered as a potential solution. Higher incidences of pollution to the rivers in Malaysia has lead to the decrease in resources for drinking water. Many developing countries like Malaysia, are faced with a big challenge to provide safe drinking water to the ever-increasing population. Currently, the treatment of river water uses chemicals to reduce several contaminants due to pollution. The chemical contents could give long term effects to the health of the consumers. However, there is hope in a more effective, but low-cost technology, known as Bank Infiltration (BI) or Riverbank Filtration (RBF). BI is a natural process using natural soil (aquifer) to treat river water and at the same time utilizes groundwater. Moreover, due to its ability to remove even the most persistent contaminants and microbes, BI can enhance treatment steps in a water treatment facilities, especially in a conventional water treatment. BI is a method that has long been known but it is still new and has not been practiced in Malaysia. Nevertheless, BI is site specific and requires thorough site investigations to assess its feasibility based on the local site characteristics. The study area was located in the southwest state of Selangor within the Langat Basin which covered an area of 10 km2. Besides, this study was specifically conducted to explore the possibility of using the BI systems to source the polluted surface water with groundwater. Three major factors were considered for evaluation: (i) an investigation on the contribution of surface water through BI, (ii) the input of local groundwater, and (iii) the water quality characteristics of water supply. In the earlier part of the investigations, the geophysical method was employed to define the subsurface geology and hydrogeology of the area. Isotope techniques were performed to identify the source of groundwater recharge and interaction between the surface water and the groundwater. A total of 25 monitoring wells and 2 test wells (DW1 and DW2) were constructed to circumscribe the BI system. The physicochemical and microbiological parameters of the local surface water bodies and groundwater were analysed before and during the water abstraction. The abstraction of water revealed a 5–98% decrease in turbidity, as well as HCO3-, SO4-, NO3-, Al, As and Ca concentrations reduction compared to the Langat River water. However, the water samples from test wells during pumping showed high concentrations of Fe2+ and Mn2+. In addition, the amounts of E. coli, total coliform, and Giardia were significantly reduced (99.9%).The pumping test results indicated that the two test wells (DW1 and DW2) were able to sustain yields of 15.9 and 128 m3/hr, respectively. The BI method looks closely at surface water and groundwater interaction. The water quality interaction was assessed through multivariate statistical analyses based on analytical quantitative data. Multivariate statistical analyses were used, including discriminant analysis (DA) and principal component analysis (PCA), based on 36 water quality parameters from the rivers, lakes, and groundwater sites at Jenderam Hilir, which were collected from 2009 to 2011 (56 observations). The DA identified six significant parameters (pH, NO2, NO3, F, Fe, and Mn) from 36 variables to distinguish between the river, lake, and groundwater groups (classification accuracy = 98%). The PCA confirmed and identified 10 possible causes of variation in the groundwater quality with an eigenvalue greater than 1, which explained 82.931% of the total variance in the water quality data set: hydrochemistry; redox conditions; groundwater flow; surface runoff; groundwater contact with rock or weathered rock (Kenny Hills Formation); river water and groundwater interaction, discharge of untreated sewage and industrial wastes into the river; interaction between the river, lake, and groundwater; heavy metal pollution from past mining activities; and industrial pollution, such as dye or paint operations. Hence, in order to evaluate the effects of groundwater pumping and BI operation on the operations of wells, as well as to determine the effects of pumping rate on flow paths, travel time, size of pumping, and to capture zone delineation and groundwater mixing in a pumping well, numerical modelling simulation using MODFLOW and MODPATH were used. The simulation involved trying different scenarios by changing the variables to perform infiltration safely and to achieve the ideal pumping rate. The results indicated that the migration of river water into the aquifer has been generally slow and depended on the pumping rate and the distance from the pumping well to the river. Most water arrived at the well by the end of the pumping period of 1 to 5 days at 3072 m3/day for test wells of DW1 and DW2, and during the simultaneous pumping for DW2 and PW1 for a well located 40 m and 20 m, respectively, from the river. During the 9.7-day pumping period, 33% of the water pumped from the DW1 well was river water, and 38% percent of the water pumped from DW2 throughout 4.6 days was river water. The models provided necessary information to water operators in the design, and the construction of pumping and sampling schedules of the BI practices. The detailed field investigation programmes obtained from this study can be used for preliminary BI system design and pilot construction by stakeholders, water operator or related agencies in Malaysia, as the study provided good methods and investigation (geophysical, isotope, grain size analysis, colloidal borescope systems and water quality analysis). The statistical and numerical methods to study the BI may also be used in other areas of similar hydrological characteristics and climate conditions

Riverbank filtration as a conjunctive use between surfacewater and groundwater for water security

Climate change has caused limited water resources in many parts of the world. In fact, high occurrences of river pollution in Malaysia have led to the decrease in drinking water resources. This causes the closure of water intakes and water treatment plants which have impacted water supply, and thus, affected economic activities in the manufacturing industry and other sectors. Riverbank filtration (RBF) is one of the solutions to providing raw water for public supply in tropical countries. RBF is natural process using natural soil (aquifer) to treat surface water and seeping from the bank or bed of a river or lake to the pumping wells where, surface water and groundwater were used conjunctively for water supply. In this study, a pilot site consisting of three areas located at Langat river basin, Linggi river basin and Muda river basin based on hydrogeology and land use were monitored. Nevertheless, RBF needed to be assessed on its feasibility based on the local site geological characteristics. Therefore, this research was carried out to fill in the knowledge gap in evaluating the capability of combined use groundwater and surface water using RBF system by using a number of research methods. For that reason, measuring the efficiency of RBF involved geophysical data, sieve (particle size) analysis, pumping test data, isotope analysis, statistical tools, numerical modelling, and water quality data technique. The physicochemical and microbiological parameters of the local surface water and groundwater were analysed before and during water abstraction. Abstraction of water revealed a 5– 98 % decrease in turbidity, as well as reductions in HCO3 −, Cl−, SO4 2−, NO3 −, Ca2+, Al3+ and As concentrations compared with those of surface water. In addition, amounts of E. coli, total coliform and Giardia were significantly reduced (99.9 %). However, water samples from test wells during pumping showed high concentrations of Fe2+ and Mn2+. From the numerical modelling, the proposed method performs filtration safely and achieves the ideal pumping rate. Results indicate that the migration of river water into the aquifer is generally slow and depends on the pumping rate and distance from well to the river. Most river water arrives at the well by the end of a pumping period of 1 to 5 days. During the 9.7- day pumping period, 33 % of the water pumped from the well was river water based on the distance at 36 m from river, and 38 % of the water pumped from 18 m distance form river throughout 4.6 day was river water. In examining the interaction between the surface water and the groundwater, environmental isotopes like δ2H and δ18O were studied primarily. The environmental isotope and hydro-chemical sampling results had emphasised that the area near river basin had a connection with the river and groundwater was actively recharging the nearriver shallow alluvial aquifer, via RBF method. The approximate hydraulic conductivity (K) values of samples taken from riverbanks and streambeds, respectively, were then calculated by employing empirical equation methods, pumping test and permeability tests indicated that the value of K was important in clogging processes and the velocities and residence times in the subsoil. Furthermore, samples of groundwater and surface water of standard drinking water quality for both wet and dry seasons have been collected and analysed for various parameters and water indices. Result was indicated that all groundwater and surface water samples can be categorised as excellent and good categories respectively. In conclusion, Malaysia riverbank were suitability of RBF systems had a higher potential area and were able to generate potable drinking water but various method such as geophysical, hydro-chemical, geochemical, stable isotope approaches pumping test, statistical tools and numerical modelling must be priority to applied during the RBF studies. RBF is acceptable as a conjunctive use of surface water and groundwater for national water security applicable during climate change

Vertical hydraulic conductivity of riverbank and hyporheic zone sediment at Muda River riverbank filtration site, Malaysia

In analysing the stream–aquifer interactions and riverbank filtration (RBF) systems, it is very crucial to determine the vertical riverbank and streambed hydraulic conductivity. The riverbank and streambed focused in this investigation are a riverbank of six layers with depths of 38 m and streambed with depths of 9 m connected layers of sediments at 22 test locations and 4 test wells in the Muda River, Malaysia. In the analysis, there were a few tests involved to determine riverbank and hydraulic conductivity of vertical streambed, such as analysis of grain size, pumping test and in situ falling head standpipe permeability tests. The approximate K values of 114 samples and 15 samples taken from riverbanks and streambeds, respectively, were then calculated by employing empirical equation methods [Hazen, Hazen K (cm/s) = d10 (mm), Terzaghi, Beyer, Slichter, Sauerbrei, Kruger, Kozeny–Carman, Zunker, USBR, Zamarin, Barr, Alyamani and Sen, Chapuis, and Krumbein and Monk]. The geometric mean of K for six layers, namely the sandy silt (8.30 m/day), silty sand (47.66 m/day), gravelly sand (150.24 m/day), sandy gravel layer (418.48 m/day), gravelly sand (151.09 m/day) and silty clay (9.36 m/day) as identified characteristics by using grain-size analyses, was greater than the K of pumping test (geometric mean) (31.10 m/day) and the mean obtained from K of permeability tests (7.03 m/day). In general, the K values of upper layer of sediments of streambed were recorded to be larger in comparison with their respective lower layer of sediments. The K value for the upper layer of sediments from all tests located at the left, right and middle parts of the river ranged from 7.56 to 54.77 m/day for upper layer, from 39.80 to 128.40 m/day for middle layer and from 9.11 to 49.92 m/day for lower layer, as described by the grain-size analysis. The value of K ranges based on permeability test indicated that the value of K was from 0.036 to 1.09 m/day for the upper layer and 0.16 to 0.68 m/day for the lower layer of hyporheic sediments zone. Based on the acquired results, the conclusion that the aquifer of the focused area shows possibility for RBF and has the potential to improve the water quality and quantity is referable