According to test results, weathered sand gravel layer spreads at the surface in 10 m depth. Below this layer, pyroclastics 2 spreads until 40 m depth. In the deeper layer lower than 40 m depth, pyroclastics 1 (tuff breccia) spreads. In this borrow area, sand and gravel at the surface and pyroclastics 2 in deeper elevation can be used as mixture of core material.