SGME T-02 Memorandum
Given the uniqueness of this area whereby the site has been maintained by the state since mining operations ceased in 1990, Heritage Minerals have not been accountable for stockpiling material to support rehabilitation. Results of geochemical modelling indicate that the final tailings solution analytes do no exceed any of the health investigation levels (HILs) and it is concluded that leaching from the tailings material is benign to human health. When tailings are appropriately stored in a well maintained TSF subject to regular inspections and monitoring, the tailings materials are generally considered benign to the environment inclusive of ecological receptors. As the project progresses and deposition into the relevant TSFs occur, ongoing monitoring of the tailings quality will be undertaken to better inform rehabilitation and closure strategies. It is only following cessation of tailings deposition that more detailed soil studies can be conducted to obtain both physical and chemical soil parameters to confirm the rehabilitation and closure strategies. Based on the lack of available cover material and considering that only at cessation of deposition can soil investigations be undertaken to determine the chemical and physical properties of the tailings, committing to a specific cover design at this stage is immature. The depth of the cover and where the material is to be borrowed to construct the cover can not be ascertained at this stage. It is likely that construction of a cover system will require the importation of suitable material from off-tenure locations. An assessment of the growth media characteristics will be completed by an appropriately qualified person to determine the amelioration requirements to suit the revegetation plan. Due to the lack of topsoil resources, growth media may also consist of ameliorated mine waste materials to be determined by an appropriately qualified person. Methods to ameliorate growth media include (but are not limited to): Integrated organic materials (compost, biosolids, straw, cane tops, biochar, fertilisers); Surface mulching (straw, canetops); and Blending suitable benign materials noting the limitations of material availability at the Mount Morgan Mine site. 1.3.6 Revegetation When developing an appropriate revegetation strategy for the TSFs consideration is given to historical research and requirements to engage with the DNRMMRRD as the underlying landowner to understand their preferred species mix. It is premature to specify the seed mix to inform this TMP as site operations have not commenced. Most of the available information regarding revegetation strategies was reported in Unger 2003. It is reported Recommendations included key species, germination requirements and soil types, with more specific recommendations relating to species most suited for providing high transpiration rates, high-quality runoff, and erosion control (Kasel et al., 2001). A summary of pertinent information is provided below: Native species such as eucalypts and acacias are the recommended species to use in revegetation, as they are drought-resistant, fire-resilient and are common in dry landscapes in Central Queensland. Several species are noted for their ability to colonise disturbed areas: Corymbia tessellaris , Acacia spp , Pogonolobus reticulatus , and the introduced species Pennisetum setaceum ; Species that are naturally resistant to fire and drought should be included in revegetation activities, with a focus on seed stocks resilient to fire and drought. Eucalypts and acacias are the most suitable species, along with species of Myrtaeceae and Proteaceae. Seed sown should be propagated without fertiliser and be sown around the time of seasonal rains; Native grasses should be used as a ground cover; however, grass seed should not be used until woody species have been established to limit competition. In areas where controlling ARD maybe difficult, a mix of native grass and pea seeds should be sown, with eucalypt and acacia tube stock introduced after the desired level of cover is achieved; and When planning revegetation on exposed areas, thought should be given to the soil type and soil cover thickness: For thin cover, short-rooted species such as grasses, peas and acacias should be considered
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