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.
Sediment basin
A sediment trap is a temporary settling basin installed on a construction site to capture eroded or disturbed soil that is washed off during rain storms, and protect the water quality of a nearby stream, river, lake, or bay. The trap is basically an embankment built along a waterway or low-lying area on the site. They are typically installed at the perimeter of a site and above storm drain inlets, to keep sediment from entering the drainage system. Sediment traps are commonly used on small construction sites, where a sediment basin is not practical. Sediment basins are typically used on construction sites of or more, where there is sufficient room.