Hydraulic Containment 

The Notice of Clean Up Action requires Orica to pump contaminated groundwater to prevent further migration of the identified contaminant plumes to other parts of the Botany Sands Aquifer. 

Orica has created three different containment areas or lines. Each containment line is equipped with a number of extraction wells with individual pumps (like that shown on the right) to extract the contaminated groundwater so it can be piped to the Groundwater Treatment Plant (GTP) for treatment.   As contaminant plumes have been identified in both shallow and deep layers of the Botany Sands Aquifer, three levels of extractions wells have been installed to ensure that the groundwater flow is fully intercepted and the contamination is contained. Typically, shallow wells run to depths up to 9 m below the ground level (bgl), intermediate wells run to depths between 10 and 15 m bgl, and deep wells run to depths up to 40 m bgl.

An extraction well at the Primary Containment Area

Orica implements a comprehensive monitoring program to ensure that hydraulic control within the containment areas is successfully achieved. Orica currently extracts about 6-7 ML/day or less of groundwater in order to achieve hydraulic containment of the contaminated groundwater. Hydraulic containment monitoring reports are produced and published as an attachment to the quarterly Progress Report.

The Hydraulic Containment Network

Aerial view of Botany Industrial Park and the Three Containment Areas

Primary Containment Area

The Primary Containment Area (PCA) (blue lines in the image above) is located on the Orica Southlands property at McPherson Street, Banksmeadow. It is equipped with 12 deep extraction wells. The containment of dissolved-phase contamination from inferred DNAPL source areas on Southlands (the Southern Plumes) is achieved in this containment area.

Secondary Containment Area

The Secondary Containment Area (SCA) (yellow lines in the image above) is located on the central median strip along a 600 m length of Foreshore Road. It is hydraulically located approximately 500 m downgradient (the groundwater flows in a south-westerly direction) from the PCA. It is equipped with a total of 41 extraction wells, consisting of 27 shallow and 14 deep wells.

BIP Containment Line

The BIP Containment Line includes two lines located on and parallel to the western boundary of Botany Industrial Park (BIP). It is hydraulically located upgradient from the PCA. It is equipped with a total of 60 extraction wells, consisting of 23 shallow and 20 intermediate and 12 deep wells. The two parallel containment lines are designed to contain a number of identified DNAPL source areas on the BIP (the Northern and Central Plumes).