Publication Details

GROUNDWATER OPTIMISATION IN JENDERAM HILIR, DENGKIL, SELANGOR

It is known that most surface water sources in Malaysia are polluted to a certain extent by various pollutants coming from point sources such as landfills and industrial waste and non-point sources of agricultural related activities. The water operator incurred higher cost of water treatment particularly when using conventional sedimentation treatment in which the high concentration of pollutants requires higher volumes of chemicals. At the same time, the disinfection by-product (DBP) is also increasing. Hence, the R&D work is being carried out on Bank Infiltration (BI) or also known as Riverbank Filtration (RBF) method as a form of natural treatment in increasing the quality of water sourced for public water supply system. BI refers to the process of surface water seeping from the bank or bed of a river or lake to the 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. The BI study in Jenderam Hilir, Selangor is a pilot project which the objective to develop a better and sustainable source of water, and provide a good platform to introduce this method in Malaysia which 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 sources with very high potential to be developed as supplementary to meet need. 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 indicated that DW1 and DW2 were able to produced more than 15.9 m3 /hr (0.3816 MLD) and 128 m3 /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 surface water sources and the test well is more than 18 m and the shortest travel time is 10 days. The study was carried out to determine the effectiveness of BI in reducing selected water quality parameters and improving the quality of river ix water which is 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 Sungai Langat. The pumping tests were undertaken to determine the effective rate of water extraction between two different lithologies of the study area. Water quality analyses were carried out for water from the Sungai Langat and groundwater from the study site and the results showed decrease 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 count were significantly reduced during the passage in BI and capable to achieve more than 99.9% removal of E. coli, total coliform and Giardia. The construction of BI method is a proactive effort of NAHRIM to improve the surface water quality as a source for domestic water of a modern urbanised area.