OVERCOMING SALINE INTRUSION IN WATER SUPPLY AT MUAR, JOHOR

Abstract

Muar River Basin is the major source of raw water supply for three states in the South of Peninsular Malaysia namely Johor, Negeri Sembilan and Melaka. For Johor, Muar River is the main source for almost all water treatment plants in Muar and Segamat districts. El Nino 2014 phenomenon has affected almost entire states of Johor where the situation has never happened before, and its impact amongst others is the intrusion of salt water into Gersik water treatment plant located at 85km from the river estuary. Water Safety Plan (WSP) team of Ranhill SAJ SDN BHD (SAJ) has acted promptly on consumer complaints following the salty water supply in Muar district on March 11, 2014. SAJ WSP team has conducted Total Dissolved Solution (TDS), Salinity and Conductivity tests at all water intakes. From the observation, pH reading of 6.7 to 6.8 at normal trend but TDS reading reads over 2000ppm from the safe standard level of 1500ppm and Chloride readings at above 900ppm levels from a safe level of 250ppm. The reading showed the increasing trends during high tides that push the salt water flow further upstream of the river. The issue of saline intrusion was reported to the relevant agencies, namely Badan Kawalselia Air Johor (BAKAJ), Ministry of Health Malaysia (MOH) and Suruhanjaya Perkhidmatan Air Negara (SPAN) for immediate control because high chloride contamination in water supply could risk the health of consumers and may caused damage as well to the safety of hospital and factory equipments. This paper is prepared to share the experience of the mitigation measures taken by SAJ in facing dry weather impact of El Nino's phenomenon that struck in March 2014 that had affected treated water supply to nearly 118,000 user accounts.