Groundwater is the general term used for water found under the ground. Groundwater runs at different depths under the ground and it has its own direction of flow just like any river, which is influenced by gravity, water pressure and ground permeability. Below Botany Industrial Park (BIP), the shallow groundwater runs at a depth of 3-7m in a south-westerly direction towards Botany Bay.
A body of underground water is known as an aquifer. The surface of an aquifer is known as the water table, which varies in depth. The aquifer beneath the BIP and the region around it is known as the Botany Sands Aquifer.
Groundwater Contamination at Botany
Contamination of groundwater at Botany Industrial Park (BIP) was first identified in a survey conducted for ICI Australia in 1990.
The environmental legacies at what is now known as BIP date back to the 1940s when manufacturing began at the site. The 1960s saw the introduction of larger manufacturing plants making a wide range of chemicals. This was an era when environmental awareness and standards were far lower than those of today, especially in understanding the potential impacts of chemical use and storage on local soil and groundwater.
During this time, chlorinated hydrocarbons (CHCs) were stored on site in tanks and drums. Some of these stored materials leaked into the ground and groundwater. It is likely that contamination was also caused by accidental spills. Even though these chemicals are no longer manufactured at BIP, their legacy continues to affect groundwater quality beneath and downgradient of the BIP.
Dense Non-Aqueous Phase Liquid
The principal source of groundwater contamination at BIP are CHCs which are present as Dense Non-Aqueous Phase Liquid (DNAPL). DNAPL can be found in the aquifer in the form of small droplets residing in the porespaces between soil particles, and as thin pools lying on top of layers of low permeability matter (e.g. peat, clay or rock).
Orica has been investigating DNAPL source areas on the Botany site since they were first identified in environmental investigations in 1993-1996. These source areas are locations where CHCs have entered the aquifer and, as they slowly dissolve, act as a source of contamination in the groundwater. These substances are often collectively referred to as DNAPL because they usually enter the aquifer as a separate-phase organic liquid that is heavier than the groundwater.
For more information on DNAPL and how it behaves, see the above video, prepared and presented by Dr Bernie Kueper. Dr Kueper is a key industry expert from Queen’s University in Canada, and participated in the Botany Groundwater Strategy Review Workshop in December 2007. The video is based on a presentation Dr Kueper made to the Community Liaison Committee at that time.
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After initial investigations identified the extent of groundwater contamination at the Botany site, Orica initiated further studies and conducted trials to help determine the most effective and safest ways to clean up the groundwater.
Remediation plans were developed as further studies continued through the 1990s. On 26 September 2003, the Department of Environment Climate Change and Water (DECCW) (now the NSW EPA), issued a Notice of Clean Up Action (NCUA) to Orica. The Notice was varied three times, on 17 February 2004, 7 December 2004, and 2 February 2006.
In accordance with condition 3B of the NCUA, Orica submitted a Groundwater Cleanup Plan (GCP) to the EPA in October 2003. The Plan provided a detailed approach for the containment and treatment of the contaminated groundwater. Challenges and issues were also highlighted in the Plan.
Once approved by the EPA, Orica immediately began work to implement the Plan. Orica provided quarterly progress reports on the implementation of the Plan, including details of monitoring of surface water and groundwater.
In 2010, DECCW reviewed the regulatory framework for the Project as initial requirements outlined in the NCUA were complete. The NCUA was revoked and replaced with a Voluntary Management Plan (VMP). The GCP is also now redundant. Most undertakings previously outlined in the GCP have been completed or amended, and key elements and ongoing activities have been incorporated into the VMP.
For more information about the current regulation of the Project, see Regulatory Approach.
Groundwater Extraction Exclusion Area
In response to the contamination issues in the region, the NSW Office of Water declared a Groundwater Extraction Exclusion Area (GEEA) in which the extraction of groundwater for domestic use is prohibited. The GEEA boundary includes groundwater that is known or suspected to be contaminated with CHCs. Suburbs included in the GEEA are Banksmeadow, Hillsdale, Eastgardens, Pagewood, and Botany.
On 22 August 2006 the NSW Government announced changes to the management of groundwater in areas situated above the Botany Sands Aquifer in response to a range of contamination sources not related to Orica. The management area has been divided into four zones (PDF 320.5KB). The GEEA is Zone 1. For further information visit the NSW Office of Water website.
Key milestones relating to the Botany Groundwater Cleanup project are listed in this project timeline. (PDF 448.9KB)
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