A numerical finite volume method in a two-dimensional domain is used to determine the temperatures in the ground surrounding multiple borefields, each consisting of 16 boreholes. Such information can help examine potential negative impacts of installing geothermal heat pump systems on the surrounding environment. The effect of implementing ground heat exchangers is considered as is the temperature rise in the soil over a period of five years, while accounting for the seasonal variation of heat input to/removal from the ground. Bin data for a building in Belleville, IL are used to calculate the building heating/cooling loads and to analyze the ground heat flows with regards to varying heat pump performance.