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

Appendix 1.

Barometric pressure observations

Appendix 2.

Barometric pressure data

Appendix 3.

Instrument Manufacturer Specifications


Instrument Service Certificate

Appendix 4.

Gyroscope Baseline checks

Appendix 5.

Hangingwall station network adjustment

Appendix 6.

Sidewall station co-ordinates using four points

Appendix 7.

Sidewall station co-ordinates using two points

Appendix 8.

STANDARD OPERATING PROCEDURE

Establishment, Propagation and Quality control of Sidewall Survey Station Networks.

PURPOSE AND SCOPE

This Standard Operating Procedure has been written as a practical guide for the installation propagation and check survey of a sidewall survey station network, in a format that will be easy to use and interpreted by surveyors with an elementary knowledge of surveying theory. The Procedure will cover both the routine tasks associated with installing sidewall survey stations as well as more unusual tasks such as the transferring of one type of survey network to another and check surveying methods. It should be read in conjunction with the guidelines and risk assessments detailed in Chapter 8. Careful preparation and adherence to observation protocol are essential to the successful establishment of a survey network within the prescribed minimum standards of accuracy. These Standard Operating Procedures are based on the minimum standards of accuracy prescribed by the MHSA.

The flow sheet, shown in

Error: Reference source not found, illustrates the process of establishing a sidewall station network and the observation protocol to be followed for a sidewall survey station network.


Figure . Flowsheet for sidewall stations. [180]

SPECIAL CONSIDERATIONS
Safety Considerations	Refer to Chapter 8 for detailed risk assessments for each of the steps of the procedure.
	All on-site procedures for working-at-heights, performing lock-outs and the inspection of hangingwall and sidewall conditions must be complied with.
Environmental Considerations	All disposable material such as paint tins and packaging must be disposed of or recycled in the on-site specified manner. Use the principle of carrying out everything that is brought in.
	Disposal or recycling of electronic equipment, batteries and power-packs must be in accordance with the manufacturer and on-site specifications.
Health Considerations	Modern total stations have the ability to direct a visible laser beam at a target. Although the laser is considered “eye-safe” it is recommended that special precautions be taken to prevent damage to the survey- and production crew’s eyes.
Quality Considerations	All surveys must comply with the prescribed MHSA minimum standard of accuracy required for the specific task.
	All observations and calculations must be stored for quality control and auditing purposes.

Phase 1. Preparation

The careful planning of a survey is critical to the success of the installation of survey control. In order to ensure a successful installation it is necessary for the surveyor to clearly understand the requirements of the work to be executed for the day. These should include discussing the requirements of the work with the supervisor, the person who requested the work (normally a production official) and most importantly the survey crew who will be assisting during that day. Preparations to be considered include:

PHASE 1. PREPARATION Check list
Sufficient crew members available to effectively execute the task.
All crew members trained in the work that needs to be done.
All crew members outfitted with the correct PPE.
All crew members familiar with the route to and from the working place.
Equipment calibrated and in good order.
Sufficient charged batteries for all equipment available.
Consumable equipment such as paint, drill bits and survey markers in available sufficient quantities for the job requirement.
Required minimum standards of accuracy for the required job profile.
Correct co-ordinate and design files downloaded on the instrument.
Permission to enter, welding permit – or similar type of permit (if needed to operate intrinsically unsafe equipment) and on site mini-risk assessments as dictated by on-site regulations obtained.
Agreed signals to be used between crew members and if possible two-way radios to provide communication over longer distances.
Communication with production crews regarding equipment lock-out requirements.
Communication regarding the “making safe” and barring of the area where survey control must be installed.

Should the preparation phase be neglected it is probable that the survey task will not be completed as effectively as required. Poor preparation lead to short-cuts in safety in order to complete the work. It should be noted that this sidewall survey station method of surveying can be a performed as a “one-man” operation, with the only constraint being the movement of equipment to and from the site. In such cases additional communication with the mining crews will be essential to arrange transport and logistical requirements.

Safety considerations
The first step in any underground survey is to obtain permission to enter the area where the work is to be performed and any relevant permission to work at height or operating a non-flameproof instrument in a production section. In an ideal environment such permission to enter would be accompanied by arranging transport to and from site and a safety inspection of the area where the surveyor plans to work. In most cases a risk assessment will be required to be performed by the survey crew either as part of the production team or independently from them. Risks to the survey crew and the survey equipment are discussed in detail in Chapter 8. Risk assessments will have to meet industry specific specifications and may vary from operation to operation.
Personnel requirements
In order to operate as an effective unit the survey crew must ensure that every member understands what the job requirement for the day is and their responsibilities in achieving the successful completion of the task for the day. Communication is the most crucial aspect to ensure the safe and efficient execution of the task. In order to ensure efficient communication, the use of radios as well as hand- and light signals must be discussed and agreed upon prior to the start of any job. It is adviseable that this should form part of the on-site risk assessment done before starting any job.
Effective communication with the production crew in whose area the work must be executed is essential. Any miscommunication between the survey- and production crew can lead to potential injury.
Recommended equipment

The equipment required for the installation of sidewall survey stations is the same as the equipment used for conventional hangingwall survey stations. The instrument used must be an electronic total station with on-board or external resection or freestation software.

Total Stations
The type of equipment used will be dictated by corporate and site-specific specifications. These specifications may place restrictions on using non-intrinsically safe battery operated equipment in areas where gas may be accumulated or where the area is defined as a “fiery mine”. Survey instruments must at least meet the following minimum requirements:

• 
  5 second absolute accuracy. Care must be taken that the accuracy specifications defined by the manufacturer are clearly understood in terms of the accuracy guaranteed and the standard deviation of readings to be expected.
  
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  Accuracy in electronic distance measuring of at least 2.5mm ± 2 ppm
  
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  On-board resection or freestation calculation software
  
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  PPM, scale factor and EDM adjustments pre-set and adjustable by the user
  
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  The ability to change batteries on the instrument without losing orientation or data
  
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  Download and upload capability that can be edited to a defined user format
  
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  Tolerances should be able to be pre-set on the instrument for positional fix on angles and distance required for the survey network.
  
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  Instruments should have sufficient battery power and at least one spare battery.
  
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  A procedure should be in place to ensure that batteries are charged and verified prior to going underground.
  

Instruments must be checked to be programmed with the correct adjustments for the site and specific level where the work is to be performed, including:

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  EDM calibration
  
• 
  Scale setting
  
• 
  Parts per Million (PPM)settings
  

In the case of a “one-man” operation it is necessary to use a robotic total station that has the ability to perform automatic target recognition and will be able to use a visible red-laser to indicate positions for the drilling of sidewall stations, the installation and painting of gradelines and design parameters that may require “marking-up” underground.
Prisms
The surveyor must ensure that similar types of prisms are used that have the same prism constants and has been checked against the manufacturer’s specifications. It is recommended that mini-prisms be used rather than the larger standard prisms commonly used for surface work. Specialized large round prisms such as the Leica GPH1 prism has a better alignment accuracy and is used in a number of operations. Some mini-prisms are encased in a solid frame that may obscure the target when observed from obtuse angles. It has been found that cutting the top part of the frame from the prisms allows the prism to be rotated and observed through a larger angle of view. Care should be taken to inspect all prisms for damage due to abrasion and paint damage in the underground environment. Chapter 6 lists the recommended equipment to be used in a survey station installation. It is recommended that individual prisms are numbered for reference and calibration purposes. In some cases it has been found that the external alignment marks painted on the sides of prisms do not always align with the true optical centre of the prism, specifically in steep sights and it is therefore recommended that the alignment and optical centre of each prism be checked prior to deployment into the underground workings.
Drills
A battery operated drill with sufficient battery power to drill approximately 25 holes per shift, which would mean 5 sets of survey stations with some allowance for additional holes to be drilled. The drill should be able to accept 8, 10 and 12mm drill bits designed for hard rock and concrete in order to ensure that all scenarios are covered for the installation of survey stations. If the on-site requirements prohibit the use of non-intrinsically safe equipment, alternative arrangements must be made. Compressed air drills have been tested but found to be unduly difficult to deploy underground.
Two-way radios
In order to overcome difficulty in communication over distances further than 10 metres the use of two-way radios is recommended. The use of radios in the underground environment is gaining wider acceptance. Prohibitions in using radios near areas that are due to be blasted must be complied with. A standard set of hand and light signals be devised should also be used by survey crews in the case where radio communication is not possible due to excessive noise or safety prohibitions.

Other equipment

Other equipment that may be required for the installation of sidewall stations will include:

• 
  Ladder. Depending on the on-site specification the ladder may have to be inspected and declared safe by an engineer. Ladders manufactured from aluminium may be banned from fiery mines as a result of MHSA regulations on light metals.
  
• 
  Tripods. The best quality tripods should be used. Aluminium tripods may be banned from fiery mines for the same reason as aluminium ladders. In addition some tripods do not have a suitable size to fit the instrument tribrach, which will lead to the instrument being unstable when setup.
  
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  Consumable equipment including paint, string, rawl bolts, grouting material, glue gun, claw-hammer, survey station sleeves and numbered disks.