The shallow groundwater table was intercepted at depth ranging from 0.9 to 3.6 metres below the surface.
In a regional context, the shallow groundwater is likely to flow towards the south (i.e., the bay), based on the results of the part 1 study.
A key determinant of what groundwater can be used for is how salty it is, which is measured by the amount of total dissolved solids (TDS). The reported concentrations of TDS varied across the area. Based on the lowest reported TDS concentration, the shallow groundwater has the potential to be a potable supply in some areas and should be protected to that extent.
Despite this, part 1 of the study concluded that the groundwater is not suitable for drinking, as concentrations of metals and other contaminants in groundwater are at levels above the relevant guideline criteria for potable drinking water supply (Australian Drinking Water Guidelines).
The study indicates the contaminants are likely to be either from diffuse sources or naturally occurring. It found elevated levels of:
- nutrients, such as ammonia and nitrate
- salts, such as chloride and sulfate
- metals, such as arsenic, iron, manganese and nickel.
The elevated contaminant levels described above potentially pose a risk to the surface water receptors that may be in connection with groundwater, such as the Yarra River and Hobsons Bay.