Remediation of NSW Regional Gasworks Site

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GHD was engaged by a confidential client to provide contaminated land and environmental planning services for the remediation of a former gasworks in regional NSW. The gasworks operated from 1879 until the 1970s, and historical coal gasification and waste disposal activities had resulted in contamination of the soil and groundwater.

GHD’s challenge was to investigate the extent of the contamination and design an innovative and effective remediation solution that would treat the key contaminants of concern including total petroleum hydrocarbon (TPH); polycyclic aromatic hydrocarbons (PAHs); benzene, toluene, ethylbenzene, xylenes (BTEX); cyanide, ammonia, and heavy metals.

GHD was able to develop a cost effective and sustainable remediation strategy for the site based on the principal of clean up to the extent practicable (CUTEP) and using a combination of in-situ and ex-situ stablisation, excavation and offsite disposal of contaminated soils.

In order to develop a robust strategy for the site, GHD completed the following activities:

  • Soil investigation using sonic drilling methods and ground penetrating radar
  • Aquifer testing to understand the flow conditions of groundwater migrating from the site
  • Permeability testing of soil samples at GHD’s in-house geotechnical laboratory
  • Development of a 3D interactive computer model of the contamination and site geology to use as a communications / conceptualisation tool
  • Contaminant flux and aquifer flow modelling by GHD Hydrogeologists
  • Detailed site investigation reporting
  • Screening of various remediation technologies to select cost effective and sustainable options
  • Preparation of a Remediation Action Plan
  • Preparation of a Development Application for the remediation including a Statement of Environmental Effects
  • Odour and contaminant vapour modelling to assess the potential dispersion of odours and vapours from excavations during remediation to protect nearby residential properties