Septic tank
A septic tank is an underground chamber made of concrete, fiberglass or plastic through which domestic wastewater (sewage) flows for basic treatment. Settling and anaerobic processes reduce solids and organics, but the treatment efficiency is only moderate (referred to as "primary treatment"). Septic tank systems are a type of simple onsite sewage facility (OSSF). They can be used in areas that are not connected to a sewerage system, such as rural areas. The treated liquid effluent is commonly disposed in a septic drain field which provides further treatment. However, groundwater pollution may occur and can be a problem.
Miami Circle
In attempting to refute this claim, Ricicek pointed to two things. Firstly there was clearly a terracotta outflow from the tank that would not tie with the need for a sink, and the plans for the apartment complex clearly show a sewage outflow to the south, into the river. Secondly, returning to the analysis of the calcite buildup on the holes by the Florida Geological Survey, the bedrock that had been cut out to lay the tank had little or no duricrust, showing the considerable age difference between the septic tank construction and the Circle.