This paper discusses a numerical model that can be used to optimize the installation in a zoned type and a homogeneous type fill dam. Before installation in a real dam to evaluate dam behavior, numerical model described in this paper is carried out on a prototype dam to check the optimum installation, using cross arm measurements. Three cross arm installations at the upstream, the core and downstream to measure displacements are considered. The installation options considered are three cross arm combinations for best installation to verify the safety of dams and to reduce cost. Finite element method is used for generating the displecement field in a linear elastic numerical model. The generated data is used as an input data in the back analysis to check the adequacy of each installation option.