Assessment of the impact of open waste dumpsite on groundwater quality: A case study of the Payatas dumpsite in Quezon City, Philippines

Abstract

Open dumpsites such as Payatas dumpsite situated in Quezon City, Philippines could pose environmental and health risk. This is in addition to the fact that Payatas dumpsite is located at the edge of the hydrologic divide between the Novaliches Reservoir and Marikina River System. A series of groundwater samplings were conducted in eighteen water well sites peripheral to both the old and new dumpsites of Payatas. Physico-chemical analyses were performed and results were compared to Philippines’ National Standards for Drinking Water and to Environmental Water Quality Guidelines. The levels of heavy metals with the exception of lead (Pb) from residential wells were found to be generally below the Philippines’ Department of Environment and Natural Resources (DENR) Department Administrative Order (DAO) No. 2016-08 threshold guideline levels and below tolerable values for drinking water standard set by the Philippines’ Department of Health (DOH). The low heavy metal contents on adjacent residential wells maybe attributed to probable nondispersionl in a halo-like pattern of the leachate from its source. Characterization of leachate samples indicated unusually high metals content and transport of the leachate through groundwater flow have been detected on nearby springs and well. Further, an unusually high Pb background (> 0.01 mg/L) relative to groundwater quality standard was inferred from the series of samples collected from residential wells around Payatas dumpsite. The very linear correlation between Zn and Pb contents in these water samples imply its inherent presence in groundwater. Experimentally calculated groundwater quality indices showed the groundwater samples collected from residential wells around Payatas dumpsite were unsuitable for human consumption. Based on the assessment findings, implications for policy and decision-making suggestions for sustainable management of Philippines’ groundwater resources are put forward.