What is Salinity?
While salinity has long been recognised as a problem in agricultural areas, the impacts of salinity within urban areas are now being more widely acknowledged. In the urban environment, the impacts of salinity can have the added affect of degrading footings, retaining walls, utilities and other structures.
Salinity occurs when salt naturally found in soil or groundwater mobilises, allowing capillary rise and evaporation to concentrate the salt at the ground surface. Such movements are caused by changes in the natural water cycle.
Salinity in the Built Environment
In urban areas the processes which cause salinity are intensified by additional volumes of water added to the natural system. Additional water comes from irrigation of gardens, lawns and parks, from leaking underground pipes and pools, and from concentrated infiltration of storm water. Urban salinity can also be related to sub-surface water flows being impeded by structures such as roads, and by poor drainage conditions on a site (WSROC, 2004).
Urban salinity can impact upon vegetation, watercourses and of course built infrastructure via chemical and physical stresses on concrete, bricks and metal. Salt moves with water into pores of bricks and concrete exposed to damp, salt laden soils. As water evaporates from the material, salt concentrates, and over-time this can be substantial enough to cause corrosion and damage the materials structure (WSROC, 2004). This is typically seen as crumbling, eroded or powdering mortar or bricks or the cracking or corrosion of concrete. Salt may also result in the corrosion of steel reinforcing and long term structural damage.
Additionally, water-logging and salts associated with urban salinity can have a considerable impact on roads, pavements and underground infrastructure. Roads can be physically and chemically degraded, becoming more susceptible to cracking, pot-holing and eventual failure (WSROC, 2004).
Contact Broadcrest to speak with an Environmental Scientist about the salinity testing and reporting option for your site.
Salinity in NSW
In NSW the leading investigation guidelines are the Western Sydney Salinity Code of Practice (WSROC, 2004), and Local Government Salinity Initiative: Site Investigations for Urban Salinity (DLWC, 2002) in addition to AS 2870-2011 Residential Slabs and Footings. This standard specifies performance criteria and specific designs for footing systems for foundation conditions commonly found in Australia.
A Broadcrest salinity investigation will include:
- A description of the development proposed
- A description of the site
- A review of salinity risk, soil landscape and geology mapping
- A site inspection
- Excavation of test pits and acquisition of soil samples
- Laboratory analysis of soil samples (pH, Electrical Conductivity, Texture, Permeability, Soluble Anion Analysis and Resistivity)
- Interpretation of the results
- Written recommendations as necessary.
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