Groundwater problems are a frequent obstacle for researchers and civil engineers in planning the handling of groundwater protection or handling a construction project carefully and thoroughly. Therefore it is necessary to conduct a study that can provide clear information about the condition of local groundwater in order to produce a more precise and
accurate handling and planning action. The purpose of this study is to determine the direction and velocity of shallow
groundwater using three-dimensional (3D) numerical modeling. The location which is the object of this research is the
Tamangapa disposal site (TPA) in Antang, Makassar City. Information regarding the condition of groundwater in this
location is very important due to the type of landfill that is open dumping which has the potential to contaminate groundwater resources due to the spread of leachate in that location. Data processing here is the process of converting primary data and secondary data into data used in numerical modeling. The results showed that the groundwater level at the TPA Tamangapa was quite varied, with the lowest groundwater level being 10.5 m and the highest being 18.9 m above sea level. The greatest groundwater velocity occurs in the west on the north side of the TPA with a speed of around 3 cm per day and generally the water flow from the TPA flows to the east which is generally occupied by people in their activities. The availability of secondary data in the study area is still considered very minimal, especially hydrogelogical data concerning soil heterogeneity. Further research is needed regarding the potential for leachate from the landfill to contaminate groundwater in the vicinity environment.