SAFETY FOR THE INFRASTRUCTURE GEOLOGIST
Figure 1. Natural Gas pipeline incidents in the US for the period 1995-2004. Source: American Gas Institute. “All Other incidents” includes corrosion, vehicles striking above-ground facilities, and surface fire.
Calling the one-call service starts the wheels in motion towards a safer work environment. You should mark in the field the location of any planned excavation with WHITE paint, and any survey points or drill location with PINK paint, as mandated by the American Public Works Association (APWA). The utility locator takes that information, compares it with his utility map, and identifies whether there is any conflict with your planned excavation. He or she will mark the area with paint or flags to identify the location of subsurface utilities. The colors used will depend upon the utility present, using the code established by consensus with the APWA. The entire list of colors used is shown in Figure 2.
high tension line is present, the safe distance from that line is 10 feet + (345 times 0.4”) = 21.5 feet away. (South Carolina Overhead Powerline Safety Initiative, 2006) Careful adher- ence to such standards may be misleading, but it’s safest to take the most conservative figure and abide by that figure. Another organization, the American National Standards Institute, or ANSI, recommends that you stay a minimum of 25 feet or more away from ALL powerlines, more in the case of high tension lines. Ten feet may be the law, but 25 feet prevents incidental contact in the eyes of ANSI. If you are using a dump truck, always lower the bed BEFORE going under the power line. Never erect a drill mast within the approved distance, and be extra careful if using a backhoe or crane around a power line.
Once overhead power lines are identified at a job site, it’s absolutely necessary to minimize their impact on what you’re doing. Call the power company and request a meeting. Seek training. Get them to reroute the power, shield the lines, or de- energize the lines. Once protective services have been sched- uled, get confirmation of what’s been done BEFORE beginning work, and no matter what ‘look up and live.’ Confirmation from the local power authority adds to your safety.
Vehicular Traffic
One of the most hazardous experiences possible for a pro- fessional geologist is working close to busy traffic. Specialized training is a must-have for every person at the job site. Furthermore, coordination and communication between all parties concerned is not only recommended, it’s essential to avoid tragedy. Principles and procedures of sound traffic con- trol are found in the Federally-sponsored Manual on Uniform Traffic Control Devices, or MUTCD. The MUTCD is considered the legal standard by which work zones operate. (OSHA, 2009.) Continuing and refresher training is also highly recommended.
Figure 2. Color coding used as mandated by the American Public Works Association
Overhead Powerlines
Often simultaneously with the underground hazard an overhead hazard is also present, so looking up and being aware of ALL potential utilities is absolutely necessary. The vast majority of electrical power delivered to homes and businesses in the United States is carried by overhead power lines. When power lines are charged, inadvertent contact with those pow- erlines may be deadly. The Occupational Safety and Health Administration of the US Department of Labor recommends a 10-foot safety margin around power lines, unless those lines have been de-energized or shielded from contact. In addition, add to the initial ten feet an additional 0.4” for every 1 kilovolt (kV) of charge over 50 kV. As an example, if a 395kV electrical
The overall goal is to avoid inhibiting the flow of traffic where possible, so when a work zone is set up, the ‘footprint’ of the operation should be minimized, thus minimizing its subsequent effect on traffic. Where possible, work should be done off the main lanes of the road and on the shoulder, but when necessary, a lane (sometimes multiple lanes) may be shut down. Lanes should only be closed during non-peak traffic hours, usually during the middle of the day or after dark. If a work zone is set up after dark, all workers should be wearing retroreflective apparel that accentuates their visibility on or near the roadway at all times. Portable light plants may be used; these should point away from oncoming traffic if pos- sible. Safety of vehicular traffic and workers in the work zone is paramount.
State Departments of Transportation (DOTs) use the MUTCD either ‘as-is’ or adapt the manual to their needs. Each state DOT is different in their preference for traffic control devices (for example Illinois DOT uses a narrow high-top traffic cone when delineating lanes while Missouri’s DOT uses a lower profile wide base cone); some states have lower or higher speed limits to respect the wishes of their residents. Nonetheless, the intent is still the same: the protection of the private and commercial vehicles as well as the workers in the vicinity of traffic control devices is an integral and high-priority element in the design of work zones.
Work zones should be checked periodically to insure that all traffic control devices are functioning as intended AND that traffic is relatively unimpeded. Adequate warning should be provided to motorists of changes in traffic patterns sufficiently
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