The site is located within the Tucson Basin, a northwest trending structural basin filled with alluvial sediments. The sediments at the site consist predominantly of sand and sandy gravel and are relatively unconsolidated down to approximately 500 feet below ground surface (bgs). At approximately 500 feet bgs, marked consolidation is seen with a corresponding significant decrease in aquifer transmissivity.  Depth to groundwater at the site ranges from approximately 290 feet bgs to 350 feet bgs, and the groundwater generally flows to the west/northwest.