This can be further confirm that sandy silt is located at 10-15 m depth and water level is full at the end of each borehole measured by DBH 2 , DBH 5 and DBH 7. By direct observation of electrical resistivity method obtained in L5, it could be possible weathered sandstone at depth > 10 m due to the high resistivity value (> 1000 ohm-m) as shown in Fig. 2, which is confirmed by the results of geotechnical investigation, DBH 1 that at depth 10 m is fractured and highly weathered sandstone.