Published on Tuesday, 3 March 2026 at 11:03:23 AM
Re: Notice of Environmental Remedial Works for Darkan Tannery
I am writing on behalf of VTA Australia (VTA) who owns the former Darkan Tannery located on Lot 1 Shield Road, Darkan, Western Australia. The purpose of this letter is to provide an update on the current status of work for progression of the site towards reuse.
The Darkan Tannery operated from 1992 to 2004 by Deras Australia Pty Ltd. Following closure due to odour complaints and prior to the sale to VTA, the site was assessed by the Department of Environment (DoE) in April 2006. A groundwater and wastewater assessment was completed by Cardno (now Stantec) in 2007 for the purpose of restart in operations (using a different process). This report found no short term risk of seepage/impacts leaving the site.
Since 2007, restart of operations under a works approval was deemed unviable and the site has been subject to some looting of wiring and general degradation of the structures. VTA engaged Martinick Bosch Sell (MBS) in April 2023 to initially conduct a groundwater assessment and subsequently a preliminary and detailed site investigations which were provided to Department of Water and Environmental Regulation (DWER). Following review of these investigations, a notice of classification letter (dated 4 June 2025 – Ref: DMO 1171) was issued from DWER stating the site has been reclassified as Contaminated – Remediation Required under the Contaminated Sites Act 2003 (CS Act) as of 3 June 2025.
Following the above, MBS prepared a remediation action plan (RAP) for the Darkan Tannery which aligns with the DWER Guidelines for Assessment and Management of Contaminated Sites. The RAP includes a validation sampling and analysis plan and proposed timeline for works. The RAP was submitted to DWER and VTA in October 2025 and approved by DWER.
It should be noted from the investigations and RAP that while there is understood to be concern regards hexavalent chromium at the site from use in the tanning process, hexavalent chromium (chromium(VI)) is not present in the disposal ponds for potential seepage to groundwater. The disposal ponds instead contain alkaline trivalent chromium (chromium(III)) which is highly insoluble and immobile towards potential for leaching to groundwater. Hexavalent chromium is also highly reactive and would (base on the site groundwater) react immediately with groundwater to produce trivalent chromium and again be prevented from further migration. Overall, the nature of the contamination at the site is limited to:
- Presence of trivalent chromium in what may potentially be plant available surface soils across areas of the site and within the disposal ponds themselves which lowers soil fertility (not a human health risk).
- Very limited presence of hexavalent chromium (and some zinc from rusting galvanised metal) in the area immediately surrounding the chrome pit and chemical storage shed. This amount is estimated to be less than 50 m3 of the uppermost soil in this area. Concentrations of hexavalent chromium here and for all metals on the site in all areas never exceeded human health risk guidelines in soils.
- The lower/northern most pond (Pond 3, used for hide "fleshing's" wastewater treatment and the original source of odour complaints), does not contain any significant metals/metalloid contamination (trivalent chromium).
The scope of remediation and validation works for the site as per the approved SAP from October 2025 is currently in the process of being costed with tenders from relevant contractors. The works, which are subject to approval by VTA (or future prospective landowner), are proposed to be conducted as soon as practicable upon the conclusion of that tender process and end of summer such that it minimises water in the ponds to be capped. Operations would be intended to be undertaken across 1 week, between approximately 6 am and 6 pm Monday to Friday. Works will entail using heavy equipment to remove and move contaminated soil from the operation and quarantine areas for capping within the disposal ponds which has a very low permeability base. MBS would oversee works to ensure completion and validation of the remediation. The chemical storage shed will be raised and site cleanup for loose metal around the process plant conducted.
Following remediation works, final soils and groundwater validation sampling will be completed to ensure remediation targets are met, as outlined in the RAP. Remediation work and validation results will be detailed in a report as per DWERs contaminated site guidelines. The report will provide details of remediation actions, methods for validation samples, soil sample locations, field observations, and assessment of results as compared to adopted assessment criteria in the RAP.
The objective as discussed with VTA and DWER is to return the majority of the site to pastoral use (grazing) with potential for beneficial reuse of the main shed and hardstand areas.
If you would like any further information or to discuss this letter's contents, I invite you to email me at lcrawley@mbsenvironmental.com.au or mnorth@mbsenvironmental.com.au and we can discuss any concerns you may have.
Yours sincerely
MBS Environmental
Louise Crawley
Senior Environmental Geochemist
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