J5 and Bungalbin East Iron Ore Proposal Response to Submissions – Appendix I Carina/J4 Rehabilitation Presentation
Carina Rehabilitation Progress Report December 2016
Background • MRL has commitments to conduct rehabilitation at the Carina and J4 mines • MRL recognises the benefits of progressive rehabilitation • Rehabilitation is undertaken utilising MRL staff and equipment, reducing costs and enabling the development of a skilled rehabilitation team. • Progressive clearing and rehabilitation has allowed for direct rehabilitation at the J4 mine, removing the need for clearing for topsoil stockpiles to reduce operating costs and closure liabilities. 2
Carina Rehabilitation Waste Landform: All batters have reprofiled to between 15-18 degrees. Approximately 80% of the waste landform batters have been topsoiled, ripped and seeded. Ancillary Areas: Removal of windrows within former operational areas has been completed in preparation of rehabilitation. Non-essential roadways have been topsoiled and ripped. Exhausted borrow pits have been progressively rehabilitated over the life of mine. 3
Rehabilitation Trials – Objectives 1. Demonstrate a range of probable rehabilitation approaches 2. Trial approaches which are most likely to provide acceptable levels of rehabilitation success 3. Prepare trials that are representative of the materials which will generally be available for use 4. Prepare trials that are constructed with techniques and machinery achievable by site personnel and equipment Rehabilitation trials were completed in August 2015. 4
Rehabilitation Trials – Methods Four methodologies were selected based on the trial objectives: 1. Topsoil and contour rip 2. Topsoil, shredded timber and contour rip 3. Deep Rip, Topsoil and shredded timber cover 4. Topsoil and deep rip Two 200m length panels were established on the waste landform on the eastern and western sides, for a combined area of 3 ha. The batters were prepared to 18 degrees, sheeted with 150mm of topsoil and hand seeded with 6kg/ha seed mix. Contour ripping was achieved through the use of a custom built plough (see previous slide). Deep ripping was undertaken by use of a single tine to a depth of 1m. 5
Rehabilitation Trial Outcomes Trials undertaken on the Carina Waste Landform have identified the following outcomes: Use of shredded timber has shown higher rate of vegetation growth over short term (18 months). Ripping through shredded timber poses significant difficulties for machinery and is not considered a viable method in large scale. Contour rips are considered to be vital for long term erosion stability. Rehabilitating with a berm width of 10m reduces accessibility of site machinery to batters. Use of onsite personnel and equipment is a viable and cost effective method for rehabilitation. 6
Selected Rehabilitation Methodology Based on the outcomes of the Carina rehabilitation trials the following methodology has been selected for Carina: 1. Prepare batters to 16-18 degrees 2. Sheet with 150 mm topsoil to a good level of depth control and trim 3. Rip on contour with a large winged tine 4. Seed with 6kg/ha standard seed mix 5. Place large logs at base to intercept sediment 7
J4 Rehabilitation Analysis of the rehabilitation of the Carina landform has allowed the following improvements to rehabilitation design for the Jackson 4 project: 1. Undertake progressive clearing and rehabilitation, allowing direct placement of topsoil onto completed landform areas (eliminating the need for stockpile clearing and increased viability of topsoil). 2. Undertake clearing to comingle understory vegetation with topsoil to increase viability of topsoil. 3. Increase berm width to 20m to allow better access for machinery (and increase long term erosion stability). Preparation of the southern and eastern batters at J4 has been undertaken. Topsoil has been placed directly onto batters ready to be utilised on the slope once at final angle. 8
Contour Survey & Pegging
Contour Ripping
Carina Rehabilitation Trial
Carina Aerial October 2016
Carina Aerial October 2016
Carina Aerial October 2016
J4 comingled topsoil & vegetation
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