DPI’S GEOTECHNICAL GUIDELINE

BRUCE MCCLURE, CMPA General Manager provides an update on the Geotechnical Guideline being worked on by DPI.

THE Department of Primary Industries (DPI) is working on a Geotechnical Guideline which will be available to assist the extractive and mining industries in Victoria.

DPI is responsible for licensing quarries and mines in Victoria with a focus on public safety, the environment, and infrastructure. Victorian legislation requires that quarries and mines are operated, rehabilitated and closed in such a manner that they are safe, stable and in accordance with community expectations. DPI states that the intent of the guideline is to provide applicants seeking an extractive industry work authority or a mining licence with requirements of Victorian legislation applicable to slope stability.

It is proposed that the document will be supplemented by the National Mine Safety Framework (NMSF) Codes of Practice on Ground Control in Open Pit and Underground Mines for sound geotechnical engineering practices for ground stability management. These Codes of Practice on Ground Control in Open Pit and Underground Mines (still in draft form) aim to provide practical guidance on how to ensure safety by taking adequate consideration of all ground control aspects relevant to the design, construction, operation and abandonment of quarries or mines.

It is proposed that this guideline will be specific to DPI’s legislative requirements and therefore would not include any obligations which may be set out in other legislation.

The CMPA made a submission to DPI on the draft Geotechnical Guideline that was sent out to all stakeholders for comment. General comment was sort from a number of CMPA members on the draft guideline and this information formed the basis of our submission to DPI.

Shown below are a number of comments on the draft guideline provided by members that were sent to the DPI. These comments have been shown as they indicate the questions that members who run quarries have regarding the draft documentation. The CMPA also sent in comments marked up on a copy of the actual document itself. These comments indicated clarity concerns and gave advice on some areas of content in the document itself where the CMPA members thought some content was not correct.

The comments from all stakeholders and the Technical Review Board (TRB) have been considered. DPI is planning a rewrite of the document partly in response to industry comments but also due to the TRB comments and some major concerns they appear to have with the current draft.

As part of this rewrite DPI are planning to introduce a new concept for all quarries and mines called the “Zone of Influence”. No other details are available at present apart from the mention of the concept.

DPI intends to release the revised draft document around Christmas this year but the CMPA did remind DPI that the industry closes down for a number of weeks over the Christmas period so it will be virtually impossible for associations to obtain comments from members during this period. The DPI aims to have the Geotechnical Guideline finalised by the end of February 2012.

In summary with documents like this Geotechnical Guideline all extractive industry members will have a valuable guide, a tool to enable them to plan for future activities on their sites with some confidence. There will always remain the need to consult with specialists on specific issues but information that this guideline will provide will be of significant assistance.

CMPA COMMENTS:

• The guideline covers a number of areas already addressed in the Work Authority and/or Work Plan. It is important that such duplication’s are removed whenever possible to avoid disputes between proponent and the DPI inspectors.
• The guideline will become an unofficial requirement when reviewing applications and variations, and may result in the further sterilisation of available resources making some sites unviable to no value to the state.
• Applying the guideline to its letter will result in highly complicated pit designs once the applicant takes into account conditions being placed upon them by referral authorities including but not limited to DSE, CMAs, AAV, local council or VCAT. There is no clarification provided as to how to prioritise the guidelines if Work Authority or Work Plan conditions contradict the guidelines.
• The guidelines do not cover a sufficiently broad range of issues which impact upon slope stability and pit design. At present only geological and hydrogeological conditions are discussed in detail, however matters such as the method of extraction, climate, blasting or not blasting (very important consideration), type of equipment used and any outside influences all impact upon slope stability.
• Although reasonable in principle, the Ground Control Management Plans (GCMP’S) need to be tested by the DPI at a number of operations to ensure that implementation is straightforward and there is not unreasonable duplication between it and the Work Authority. Testing would also provide the DPI’s inspectors an appreciation of the time it would take a site to develop and implement such a plan.
• The GCMP requires considerable data collection and analysis which is a new obligation for many smaller operations, and direction to assistance on this area needs to be provided.
• The guideline implies the Work Authority holder or their quarry manager will need to consult with an external expert at considerable cost concerning the ever changing geological conditions on the site, and questions how this will tie in with explosives obligations especially if there were an incident as a result.
• The ongoing assessment and review of the site’s compliance hasn’t been discussed in suitable depth, which is of concern as resources very seldom remain consistent throughout their life. For instance, what consultation obligations would exist once the site is in operation and how frequently should the GCMP be revisited?
• The guideline documents acceptable designs for risk category 2 sites, but does not identify if this also applies to other categories. Furthermore, there are differences between this table and other similar tables published by the DPI in relation to rehabilitation bonds. It is essential that such contradictions are eliminated, and that such changes do not result in additional rehabilitation liabilities upon existing sites.
• The guideline shows a figure outlining the DPI’s minimum crest and bench detail requirements for rehabilitation and site closure. In it, it specifies a chain mesh security fence with 3 barbs as being the requirement for boundary fencing. Has this removed the option of an agricultural stock proof fence?
• Throughout the guideline, there are several terms and concepts (i.e. GCMP, stability management procedures) which are new particularly to the extractive industry and as such should have more clarification either by way of a glossary or examples.

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