"The Legacy Mines Program (LMP) within the Department of Regional NSW has engaged the Soil Conservation Service (SCS) as lead contractor to undertake remediation works at the Lake George Mine. The mine is located immediately West of the township of Captains Flat, New South Wales (NSW).

Mining operations (for silver, gold, copper, lead, and zinc) in the area commenced in the early 1880s with several small operations amalgamating to form the Lake George Mine. Mining continued until 1962, when the Lake George Mine officially closed. The site is heavily contaminated with metals and metalloids (including lead, arsenic, copper, and zinc) and sulphur & has undergone a succession of remediation works since 1972.

The proposed remediation works are required to prevent serious environmental and human health risks to people accessing the site, to residents on-site and in the town of Captains Flat. All works will be conducted in accordance with a suite of Management Plans, environmental controls and strict occupational hygiene and workplace health and safety controls. The project is expected to take up to twenty-four (24) months approximately, with extension options of three (2) x six (6) months with environmental monitoring to commence on award.

Soil Conservation Service requires the expertise of a subject matter expert in dewatering, water transportation and contaminated water treatment, storage, and re-use onsite within the Captains Flat project. The site is classified as a ‘zero discharge’ site due to the contaminated level of the water (refer attachments 3 and 4) and therefore requires all water onsite to be captured in permanent basins (see conceptual Attachment 1) to be treated insitu to:

A level that could meet or exceed the 80% level of protection trigger values for freshwater species according to Australian New Zealand Water Quality Guidelines (ANZG, 2018).

SCS will be sizing these basins, however it can be assumed these permanent basins will be at minimum 2ML-3ML in capacity.

The water once treated within permanent basins is to be stored in onsite water tanks where water carts are to utilise as their water source. All other temporary basins onsite are to be appropriately connected to the permanent basins using hydraulic lines and pumps that can be triggered either manually or via AHD level trigger point systems.

SCS is seeking for the successful contractor to manage the water levels onsite and treat the water accordingly on a wet hire rates basis.

SCS is seeking for subject matter experts to seek to treat the water preferably with chemicals proposed in Attachment 4 however you can provide an alternative treatment proposal to reach design criteria if there is proven efficiency.

Proposed CDU Concept (Attachment 1) is conceptual only and exact methodology will need to be in collaboration with the successful tenderer which will tie-in into the site-specific Surface Water Management plan which is subject to review by the EPA.

SCS is also seeking for subject matter experts to have a provisional line-item price to conduct a review of their proposed potential water treatment process to assess the potential ecotoxicological impacts of the treated construction water for both on-site beneficial re-use and should an off-site discharge occur. For further detail for scope for provisional item 1, please refer to attachment 7."