Roof control plans

The elimination of black powder The adoption of systematic roof-control plans The installation of main ventilation fans... 

Roof control plan implementation begins by instructing aU persons who are affected by its provisions. The approved plan and any revisions must be available to the miners and their representatives and must be posted on a mine bulletin board. 

Subsection 75.221 lists the information that must be included in the roof control plan. Some of the most important issues include ... 

The roof control plan sets forth minimum requirements, specifically in areas such as bolt length... 

By definition, roof support activities take place very close to unsupported roof. Therefore it is not surprising that most of the fatal accidents involved roof bolt operators or other miners engaged in roof support. Based on the accident record, single-head roof bolt machines appear to be a risk factor. Roof control plans carefully specify the sequence of bolt installation with single-head machines to avoid placing the operator inby support. If these guidelines are not followed, the roof bolt operator can be at risk. 

The roof bolt machine, with its ATRS and canopy, is the critical piece of safety equipment. It should always be in proper operating condition before it is used. The proper bolting sequence, as defined in the roof control plan, must always be followed. Several fatalities have resulted when operators of singleboom machines installed bolts out of sequence and placed themselves under unsupported roof. 

Traditional roof control plans require that numerous timber posts be set during each stage of pillar recovery (Figure 23.6). Recently, mobile roof supports (MRS) have become available that replace many of the timbers (Figure 23.7). MRS resemble longwaU shields mounted on bulldozer tracks. They can have many safety advantages over timbers. In particular, they are more effective as roof supports, they do not require workers to approach the mined-out gob area to set them, and they reduce the potential for materials handling injuries (Chase et al. 1997). 

Following the roof control plan is absolutely critical to safe pUlar recovery operations. Fatality investigations have frequently found that lifts were too wide, too deep, or out of sequence. The plan may also specify the minimum dimensions of the remnant coal left in place called stumps and fenders. However, the roof control plan is a minimum plan, and additional supports should be used at any indication of bad roof. 

Many roof control plans specify the maximum spans that are allowed. Mining sequences can also be designed to Umit the number, location, and size of turnouts, and to restrict turnouts to specific entries. Extra primary support, such as longer roof bolts, installed within intersections can also be very effective in reducing the likehhood of roof falls. On the other hand, replacing four-way intersections with three-ways may be not be an effective control technique. Three-way intersections are more stable, but since it normally takes two three-ways to replace one four-way, the total number of falls is hkely to increase (MoHnda et al. 1998). 

Becau.se agencies do not always specify how standards must be implemented, safety officials must transform regulations into practices and procedures (Document E) that can be applied across many different sites and conditions. At the local level, writers must develop ventilation plans, roof control plans, and general safety instructions that take into account differences in local conditions. In the mining industry, these plans must be approved at the District level before operators can proceed with their work. 

Training and instruction (Document F) returns us to local sites where specific details of operation must be communicated to workers and management in new-miner training sessions, daily work orders, and annual refresher training. Workers need specific instruction in how to follow a roof control plan, how to install roof support, and how to maintain and monitor ventilation. Much of this instruction takes place on the job where novices learn as they work alongside experienced miners. 

Always comply with the roof control plan. 

Examination of this list reveals that it is not simply a list of six hazards for which plans must be developed. It refers to both specific hazards (e.g. spontaneous combustion) and general control systems (e.g. ventilation management), which may be applicable to more than one hazard. The principle hazards are to some extent implicit in this list. They include methane gas explosions (which may or may not trigger coal dust explosions), carbon monoxide poisoning, roof or wall collapse, and the long latency period dust disease, pneumoconiosis, which has probably killed more miners in the long run than anything else. 

Despite this dynamic uncertainty, engineers must construct plans to control risk and predict hazard in the everyday working operations of the mines. Roof-support engineers, for example, must map underground faults, determine stress and load levels, and construct plans that outline the minimum support methods and requirements for each section of the mine. These support requirements include a broad plan for overall roof support as well as site-specific rules for pillar width and additional support. But engineers must also be prepared to respond to change. 

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