In this paper, we present how the finite element method (FEM) can be utilized to analyze the influence of an additional substance in the trenches surrounding the grounding grid's conductors on the grounding grid's performance. For this purpose, we modified the preliminarily existent FIELD_GS program code in such a way that the additional substance in the immediate vicinity along the grounding grid's conductors can be simulated. Different soil structures and various volumes of the additional substance in the soil have been analyzed to prove the suitability of surrounding the grounding grid's conductors in trenches with the additional substance instead of strewing a whole grounding grid's surface with the additional substance