The Quezon City Controlled Dumping Facility (QCCDF) has been the ‘main disposal site of
Quezon City, the largest city within Metro Manila since the 1970s. With the huge volume of
wastes received every day and with no protective liner on the old mound and creeks directly
connecting the facility to Marikina River, the main river system in eastern Metro Manila, surface
and groundwater contaminations have been a critical concern. The main objective of the study is to
determine the effect of the disposal site on the surface water and groundwater quality by evaluating
the water quality at different points in and around the landfill. Secondarily, it aims to investigate
correlations between the water quality parameters as well as determine any seasonal effects on the
water quality. Sampling points from wells on and around the facility were collected for six months
covering dry and wet season using Horiba water quality monitoring equipment and CHEMetrics V-
2000 Photometer. Leachate quality parameters pH, turbidity, DO, and chloride are not affected by
the change in seasons as evidenced by statistical t-tests. Temperature is higher during the wet
season, while TDS is lower at this time which may be attributed to dilution due to rainfall. DO and
turbidity in leachate is strongly negatively correlated, while temperature and C1‘ in leachate are
positively correlated. In groundwater, the change in season affects temperature, TDS and chloride
concentrations. This trend is not evidenced in pH and turbidity. TDS and chloride are correlated
with each other. Based on the surface water quality measurements, temperature, pH, DO, and TDS
are affected by the change in season while turbidity and chloride are not, based on the comparison
of samples taken from different locations. Aside from strong correlation of Cl’ and TDS, as seen in
groundwater, very strong correlations are also observed between Cl’ and DO, and TDS and DO.
Using chloride ion as indicator of leachate, the study reveals that the leachate tends to spread
downward towards Marikina River. Based on the comparison of chloride concentrations near the
outfall of the leachate creek at Marikina River, it can be seen that the release of leachate at the river
impacts the river as evidenced by an increase in chloride concentration downstream of the outfall.
