Spatial positioning of sidewall stations in a narrow tunnel environment: a safe alternative to traditional mine survey practice

. A proposed guideline for the establishment of a Sidewall Station Survey network

1. Introduction

Today Mine Surveyors find themselves in a rapidly evolving environment characterized by continuous technological innovation. In this environment the South African Mine Surveyor remains responsible for the accurate determination of all underground workings relative to surface infrastructure, excavations and mine boundaries. An unplanned breakthrough may result in a loss of life or severe injury to mining crews as a result of falls of ground, injury by explosion or the inrush of water, mud or gas into a working end. The financial implications of mining a tunnel off-direction or off-gradient can have severe repercussions to the profitability of a mine and could potentially sterilize ore reserves. The ever increasing depth of mining, coupled with increased mechanization to address the demand for natural resources is placing a greater demand on Mining Engineers and Mine Surveyors. [88] Such mechanization of mining layouts has led to increased tunnel dimensions and coupled with the focus on health and safety has made the task of installing survey stations in the roof of an excavation a difficult and often dangerous activity.

Modern survey instrument technology is continuously offering improvements in the accuracy obtained coupled with calculation and storage ability. These instruments are robust, reliable and able to perform complicated calculations while still underground. The surveyor can be guided through the observation procedures and check for errors as observations, in some cases preventing further observations until predetermined limits of accuracy are met.
The lack of suitably qualified mine surveyors and mining supervising personnel in South Africa requires a change in survey methodology in order to ensure that the installation of survey control is completed to the highest standard of accuracy, while at the same time causing the minimum disruption to the production process. The use of modern surveying equipment coupled with resection techniques provides an alternative method of surveying that has the ability to improve the safety and accuracy of survey networks in narrow tunnel environments.
The method of using a cluster of four conveniently positioned sidewall survey stations, preferably in a grade-peg configuration, has been tested under both controlled conditions and under the realistic production conditions of a working mine. The results of these evaluations have indicated that the method of a random setup orientated from a cluster of four survey stations is a safe and accurate alternative to the conventional hangingwall survey method currently employed by most South African surveyors. The sidewall survey station method has been proven to meet the minimum standards of accuracy prescribed by the MHSA during the testing and evaluation phases of this research.
In order to present the new knowledge obtained through this research in an organized manner, the procedures investigated and ultimately used during the research phase will be combined with the findings in the format of a survey guideline.
The contribution to new knowledge is not the proposed method of surveying, nor the calculation of the co-ordinates using this method. It is in the proof that there is a safe and accurate alternative method to traversing, even in a narrow tunnel environment. When considering the risks of installing survey control and setting up under a hangingwall station, the contribution of the sidewall method of surveying to the mining industry and government’s goal of “zero-harm” to workers is considerable. The exposure to the risks posed by the three major contributors to injuries and fatalities namely, fall of ground, mobile equipment and falling from heights are significantly reduced.

8.1.1. Scope of this guideline

These guidelines will cover the establishment, propagation and check survey procedures for a sidewall survey station network. The guidelines will also include the procedures to be followed in the establishment of a sidewall station survey network from an existing hangingwall survey network. All the aspects of a sidewall survey network establishment including installation, calculation and check surveying will be covered. A standard operating procedure outlining the detailed technical aspects of this guideline is attached as an Appendix and should be read together with this guideline.

Risks assessments of every aspect of mining activities are required on most South African mines. These guidelines will attempt to list the most common hazards during each phase of the surveying process in the form of a risk analysis. The hazards and risks identified are generic in nature and are not intended to be an all-inclusive risk identification process. It is intended that each mining operation will identify their site specific unique hazards and address these as required by site and corporate safety protocols. The standard operating procedure in Appendix 7 has been planned to address practical issues that may be encountered during normal operations by a surveyor with an elementary knowledge of surveying.

8.2. Change management

The adoption of new or alternative survey methods to mainstream mine surveying practice is difficult when surveyors are under constant production pressure. These pressures make the testing, training and implementation of alternative methods practically impossible on established mines, unless tangible proof can be provided of the immediate advantages of any such system can provide. Resistance to change amongst Mine Surveyors [158] has been identified as posing a potential risk to the successful implementation of the sidewall station surveying method on mines where more traditional methods of surveying are still used. The hope that “the numbers will speak for themselves” will not be realistic. South African Mine Surveyors have been using hangingwall survey networks for nearly 100 years. The methodology of establishing and ensuring the quality of a hangingwall survey network is well understood and trusted. Pretorius and Crous observed that South African Mine Surveyors are reluctant to adopt new technology or surveying methods [158] unless they have been tested and the successes obtained by using this method have been published and discussed. This characteristic of a good Mine Surveyor is to be encouraged and nurtured by providing sufficient information regarding all aspects of the establishment and quality control of a sidewall survey station network. It is proposed that the method be used in areas where specific constraints may require a new approach to reducing the risk exposure of Mine Surveyors or where design or ground conditions may require an alternative approach to surveying.