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

8.3. Proposed guidelines for the establishment and propagation of a sidewall station survey network

A high level flow diagram, shown in

Error: Reference source not found, illustrates the process of establishing a survey network that is be used to provide an outline for the preparation of the survey guidelines.



Figure . A high level flow diagram of the survey process. [180]

8.4. Phase 1. Preparation

The careful planning of a survey is critical to the success of a surveyor when installing survey control, in order to evaluate the factors that will have an impact on the physical safety of the survey crew as well as the integrity of the survey network. The main factor linked to the successful and accurate completion of a survey task is the efficient communication between surveyor, supervisor, crew and production crews. A lack of understanding and co-operation between any of these parties will impact negatively on the success and accuracy of a survey.

1. Safety considerations

On most South African mines it is standard practice to perform a risk assessment of the work to be performed during a shift. Such risk assessment is essential to ensure that the risk exposure is minimized or mitigated as far as possible. Aspects of risks recommended for evaluation are listed in the following risk assessment:

Table . Risk analysis for the preparation phase of installing sidewall stations.

Risk	Hazard	Contributing factors	Mitigating Actions
Potential injury to survey crew or survey instrument	Unfamiliarity with site and procedures Unfamiliarity with survey method	No or limited communication with supervisor, crew and production personnel Lack of training, “buy-in” in method	Proper , survey related induction Training Change management
Potential injury to survey crew or survey instrument	Moving Equipment	Rail bound equipment Trackless equipment Conveyor Belts Winch / Scraper Persons carrying drill steel, timber and rails or dragging cables and pipes	Wear correct PPE (reflective) Obtain permission to enter area Lock-out, Stop or Barricade working area Communicate needs with production supervisor
Potential injury to survey crew or survey instrument	Slip and Fall Tripping over material and equipment	Footwall conditions: Loose material, Mud or water accumulation Rails and sleepers Tripod instable as a result of footwall conditions	Wear correct PPE Take care when moving around site Ensure tripod is stable Lighting
Potential injury to survey crew or survey instrument	Ground Conditions	Hangingwall Sidewall Geological conditions	Obtain permission to enter area Request inspection and barring by appointed person
Potential injury to survey crew or survey instrument	Environment	Gas present / Fiery mine Noise Illumination Dust Water vapour Fumes (Blast / exhaust) Laser light emission Thermal (too hot or cold) Strong ventilation	Intrinsically safe equipment / welding permission (site specific) Wear correct PPE Additional lights must be used where required Ensure prism and instrument is acclimatized Use radios or pre-arranged hand or light signals Laser pointer of instrument to be aimed with care and non-survey personnel warned of the danger
Integrity of survey network compromised	Inadequate training and education	Not familiar with survey fundamentals Not familiar with instrument or software Not familiar with observation protocol	Ensure all surveyors have been adequately trained in all aspects of the survey required Establish minimum level of education
Integrity of survey network compromised	Communication	No communication between survey crew and production crew	Communicate job requirements to survey and production crew
Potential injury to survey crew or survey instrument Potential error in survey propagated	Production pressure	No communication between survey crew and production crew	Obtain permission to enter area Ensure the job is discussed and cleared with the production supervisor

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Each of these risks should be evaluated and discussed to understand how the risk can be avoided, mitigated or reduced. Such risk assessment will have to meet industry specific specifications which will vary from operation to operation.

2. Planning of the network

A factor often overlooked in the establishment and extension of a survey network on a mine is the planning and error analysis of a survey network. When a new mine is planned and developed, care should be taken to ensure the accuracy of the shaft sinking and transfer of the meridian into the underground workings. It is recommended that the survey network should be planned and evaluated with the same care prior to a network being established, and should include the process of estimating extent of error propagation, the required accuracy of the networks, the placement of baselines, control points and check surveys. The boundaries between primary, secondary and tertiary survey networks with their individual accuracy requirements should be clearly defined and planned. The parameters decided upon can be dictated by corporate standards established from the results of existing survey networks within the domain of the specific mining industry and the results of any check surveys. The results obtained from the final phase of the process of check surveying are to be used to fine tune the next iteration of survey planning.

The financial impact of the accuracy of the survey model surveying on an ore reserve is represented as a cause and effect diagram in Figure . The diagram should be read from the bottom of the diagram.


Figure . A cause and effect diagram of survey information. [181]

3. Equipment used

The equipment used to install sidewall survey stations is similar to the equipment used for conventional hangingwall station surveys. The equipment list described in Chapter 6 and attached as Appendix 10.. This list describes the recommended equipment to be used in a survey station installation. In general the type of equipment will be dictated by corporate and site-specific specifications. Such 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”. The use of ladders or equipment manufactured out of aluminium is restricted in mines classified as “fiery mines” due to the inherent risk of thermite reactions that may occur between oxidized metal and aluminium.

Specific equipment requirements will be discussed in the Standard Operating Procedures in Appendix 7. Regardless of the make of instrument selected on site the specifications of the instrument used must at least conform to the following minimum requirements of 5 second angular accuracy and measuring accuracy of at least 2.5mm ± 2 ppm. Instruments should have the ability to be “field serviced” by the user in the case where minor corrections or adjustments are required to be made to the instrument. These adjustments must include EDM calibration, scale and ppm settings. In the case of deep level mines with significant difference in pressure between surface and the underground levels a mine specific standard must be developed to address the setting of scale and PPM factors per level or to maintain the same setting for the entire site.
Prisms are in general not serviced or maintained to the same degree as a survey instrument, it is essential that the condition of all prisms be checked before commencing a survey task. It is recommended that the prism optical centres be checked to coincide with the reference centres of the prism housing before being used underground. Large round prisms are more likely to have a discrepancy between the observed optical centre and the true optical centre. Where possible then mini-prisms designed for accurate work should be used. Prism attachments must be checked against the manufacturer’s specified dimensions. It has been found that manufactured attachments do not always comply with the designed dimensions and specifications.

4. Personnel requirements

The level of training and education of the surveyor, survey crew and in the case of an operator (mining person) must also be taken into consideration. Although modern instruments are mostly intuitive in the guidance of an operator through a specific observation protocol, all operators must be trained in the theoretical aspect of making a resection observation. It has been found that in some cases days are spent in ensuring that a new employee is inducted into the safety aspects of operating underground, but that little time is spent on ensuring that the surveyor understands the observation protocol and instruments used on a specific site. In the case where sidewall survey stations are to be used as an alternative method of surveying it is advisable to introduce the method using proper change management procedures to ensure “buy-in” and compliance with the new method. The following generic hazards have been identified in the following risk assessment:

Table . Risk analysis of equipment use during the installation of sidewall stations.

Risk	Hazard	Contributing factors	Mitigating Actions
Survey results do not comply with minimum standards of accuracy	Off-line mining Mine layout must be changed Unplanned breakthrough Mis-holing of excavations Damage to structural design (pillars) Error Propagation	Instrument settings: Prism constant Scale factor EDM calibration Operator skill level	Regular calibration Check against baseline PPM setting per level or standard for mine Operator training
Damaged survey reference survey stations	Off-line mining Mine layout must be changed Unplanned breakthrough Mis-holing of excavations Damage to structural design (pillars)	Prism affected by dust or vapour Blast damage Theft or intentional vandalism Damage during installation Damage by mobile equipment Rock movement or scaling due to pressure or geological factors	Ensure prisms are clean Use non-metal survey stations Ensure stations are placed in area where probability of damage is minimized Protect station with rubber mat or similar cover
Damage to instrument	Loss of production Financial loss Loss of adjustment and calibration	Slip and Fall (floor conditions) Moving personnel and machinery Instrument not fastened to tripod Damaged tripod Incorrect tripod (head size)	Survey fundamental protocol Communication between crew and production personnel Barricade, lock-out procedures
Potential injury to survey crew	Hand tools	Drill can injure operator Hammer can injure survey crew member or survey station if improperly used.	Equipment in good condition Training in use of equipment Use expanding bolt type plug
Instrument not adjusted correctly	Incorrect scale or PPM setting Incorrect mask for capturing observations	Lack of standardized PPM settings User not allowed to make adjustments	Training in use of equipment Regular calibration Check against baseline PPM setting per level or standard for mine

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