The depth, thickness and expanse of sandstones or sandy material in site candidate of the disposal demo in Serpong nuclear area (SNA) need to be identified. This is considered because sandstones as ground water aquifers will potentially serve as a medium for transporting radionuclides from waste to biosphere. For design optimization and safety assessment of radioactive waste disposal facility so as not to endanger the public and environment, it is necessary to identify the sandstone layer data. This study was conducted with primary data at SNA using the Wenner configuration of resistivity geoelectricity method on five lines. Data processing and modeling is done through RES2DINV software to obtain the resistivity value of rocks that represent sandstone beneath the surface. In the line 1, the sandstone is at a depth of 6 m and 10 m with a resistivity value of 2,13 – 9,40 Ωm. In the line 2, the sandstone is at a depth of 12,5 m and 17,5 m with a resistivity value of 0,51 – 1,43 Ωm. In the line 3, the sandstone is at a depth of 18 m with a resistivity value of 0,70 – 3,28 Ωm. In the line 4, the sandstone is at a depth of 30 m with a resistivity value of 3,97 – 8,48 Ωm and in the line 5, sandstone is at a depth of 16 m with a resistivity value of 1,12 Ωm. Based on the results of the assessment, all the lines meet the safety requirements of radioactive waste disposal because there is a sufficient barrier zone between the base of the repository and the sandstone as groundwater aquifer, line 1 has a thickness of 4 m and 8 m, line 2 has a thickness of 10,5 m and 15,5 m, line 3 has a thickness of 16 m, line 4 has a thickness of 28 m and line 5 has a thickness of 14 m.
