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The space available for work will affect both machines and workers. By Paul Hull |
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Confined spaces mean different situations to different people. Some Europeans are amazed if we say there are any United States projects where space is limited, and there are many in the US who have never had to maneuver their excavators or loaders in narrow streets where the passing of two vehicles is a work of art. Ask a contractor who repairs house foundations or basements, and he will tell you what a confined space really is. Ask a contractor who has had to work close to a property with the proud owner standing by, and he also will tell you what a confined space really is. Our government says confined spaces are sites where the configurations hinder the activities of any employees who must enter, work in, and exit them. Among the more obvious examples are trenches, pits for any underground construction, and parts of buildings that are accessible only to crawling and stooping workers. Road repairs and construction with those temporary barriers (sometimes ill-defined and with vehicles speeding by) must seem to be confined spaces to many workers. "I think being in prison must be a bit like this," comments Mike Wooten, who has worked interstate and state highway rehabilitation in Minnesota, North Dakota, Montana, and Wyoming. "You feel you are trapped by the barriers, equipment, and traffic. You never look forward so much to lunch break or escaping to the grassy median."
To everybody, working in a confined space means you cannot move yourself or your equipment around as freely as you would like. It's uncomfortable. The site can be above the ground or below, and just how confined it seems will depend on what you and your crews are used to. We asked contractors about two basic confined spaces: sites big equipment cannot access and places workers had to crawl, bend, stoop, and wriggle to reach. One aspect mentioned frequently enough to bear repetition here was that all confined spaces seem to make noises louder. Make sure your equipment meets local noise regulations when it is working in an unusually restricted area, and make sure workers can hear instructions, especially if they are wearing protective ear wear. A good percentage of contractors we spoke to have turned down jobs where special equipment and protection (which equals additional costs for just one project) were required. Most of them seldom face the problems of confined spaces; these problems are not part of their everyday routine. "We do a lot of residential work," comments Brent Gentry, whose G&G Construction & Excavation is in Cookeville, TN. "We don't meet many confined spaces in our work, not places that need special methods or equipment. We do trenches sometimes and obviously have the right shoring for those jobs if the conditions warrant it. But confined spaces where you have problems moving around are not everyday problems for us."
The Rise of Compact
Equipment
An excavator operator who is used to swinging the boom freely because there is seldom any other equipment or person nearby, will need special instructions and cautions if he has to work in a narrow space between buildings or in a work envelope where his movements are restricted by passing (and not always slow) traffic. There are machines built for such conditions, and if your work is mostly in confined spaces, you should consider owning them rather than the larger equipment you grew up with. A phrase you might see frequently is zero tail swing. Simply, it means the operator can work his boom without fear that the rear end of the machine will demolish the building, equipment, or foreman behind him; the concept became popular for work in narrow streets and alleys. It reminds me of a scene in Kelly's Heroes where a tank cannot move its gun barrel in a big enough angle to line up with the targets (Clint Eastwood and Donald Sutherland) because there's a solid tree on one side and another obstruction on the other.
An Abundance of Models
"Obstacles are everywhere for today's contractors," John Deere reminds us. "Whether you're working in an urban setting doing close-quarter street work, digging underground utilities near delicate landscaping, or working within the confines of a single lane on a busy highway, you need an excavator that not only swings but swings tight." That was the philosophy behind the development of Deere's RTC excavators: reduced tail swing. They are configured without the traditional counterweight. Bobcat, which started the trend toward compact construction equipment with the first skid-steer loader many years ago, today offers compact excavators, skid-steers, and tracked loaders. The T300 compact track loader has found great success at new-home sites for digging crawlspaces and foundations, backfilling, final grading, and cleanup work. "I can do just about every site preparation job you can imagine with my T300 loader," says Mike Hauser, a contractor from Fairview Heights, IL. "It enables me to do all the work by myself. I average about 1,200 hours a year on my loader. The flotation of this machine is especially important when digging basement foundations." In Burlington, NC, Troy Starnes uses a compact Bobcat B100 loader backhoe in his water- and sewer-line installation projects. "It's the right size for working efficiently in limited-access areas," observes Starnes. "We used to rely on others for our digging work, but sometimes we had to wait a day or two for them to show up. Now we can do the work on our schedule."
An interesting aspect of compact equipment is that it has started to get bigger. It still is compact, compared with yesteryear's standard big excavators, loaders, and backhoes, but it is gaining size, power, and versatility. An example is Komatsu's latest skid-steer, the SK1020-5. It's this manufacturer's largest model, a 7,525-lb. unit with the only standard two-speed transmission in the industry. It has the Komatsu HydrauMind hydraulic system, which allows for simultaneous machine functions without sacrificing engine power or speed, and can use 40 different attachments. This is not a "mini" type of machine, but it can claim to be compact. At the other end of the scale, Volvo has introduced its very small EC13 compact excavator with the rental market and individual user in mind. "We found that new entrants into the 1.5t [ton] class were actually getting heavier and heavier—some as high as 1.7t and 1.8t," notes Didier Lavigne, product manager for compact excavators at Volvo. "This situation was running contrary to one of the original purposes of this size machine, namely, the ability to transport it easily. Larger machines actually cause transport overload problems, and customers said they needed a dedicated truck and trailer to handle them." Remote control is another technique developed because of dangers in confined spaces. Trench rollers and reversible-plate compactors from Bomag are examples of this way of managing normal work made more difficult by the dimensions of a site. The risk of cave-ins harming trench workers is eliminated by the remote-control option for the machinery. There are similar approaches to handling equipment for work inside buildings, where restricted space can turn a simple, everyday task into a dangerous challenge. Some demolition projects work inside old buildings and proceed from the top down. The equipment that does interior demolition is usually small—for example, a skid-steer. There is unavoidable dust and noise; workers should wear the appropriate protective gear. Some interior demolition involves destroying concrete slabs with hydraulic breakers or hydrodemolition machines. Again, there are remotely controlled machines to do that, from such manufacturers as Brokk, Aquajet, and Conjet. For those who go in, make sure their power hand tools have ground-circuit interrupters and their air-operated or electrical equipment is nonsparking. There is sometimes no proven reason why an accident happens. "We had to assume that a spark from the welder met some undetected gas," explains Terry Ringen, whose work takes him into several western states. He was doing repairs inside a small storage building in Wyoming when an accident occurred. "We have rules for monitoring gas, but it's possible the guys went for coffee and did not check again when they came back. There was an explosion, and the roof of the building blew right off. Luckily nobody was injured." Many contractors rarely, if ever, have their workers in confined spaces because their everyday business is aboveground and offers adequate room to move machines, tools, and workers. Even some of those you would expect to face confined space problems seldom do. Thedford Construction Company in Tyler, TX, specializes in electrical underground construction. That can mean trenches up to 3 ft. deep and wide. They are big enough for workers to operate in, but they are not considered dangerous enough for special equipment (other than the specialized equipment and tools the company always uses). "We rarely have a confined-space problem and have no requirement for special respirators or anything like that," notes Kelly Thedford. Far north of that company, in Okemos, MI, Ellis & Son Construction Company builds homes and seldom sees problems related to confined space. In Spanish Fork, UT, H.E. Davis Construction Inc. works with sewer lines and drainage. "We encounter confined spaces infrequently," comments Cameron Holman, whose roles at the company include safety coordinator. "We give training internally to our employees before they work in any confined spaces. It seems to happen most often when we put in drainage boxes and have to grout around the piping."
Safety All Around The Occupational Safety & Health Administration (www.osha.gov) has standards relevant to confined spaces. In the Unified Agenda they are in Part 26, which deals with construction and confined space and excavations. Although examples given tend to be for work done in "process vessels"—things like storage tanks—you should be aware that sewers, vaults, manholes, and many trenches provide similar levels of danger for workers. Your everyday jobs might involve such sites only rarely, but most contractors come across confined spaces and enclosed (often underground) areas when they are doing repairs on existing structures—office buildings, hospitals, houses, apartment complexes, schools, and banks. Manholes and ventilation ducts are among the most common. Sometimes the problems are caused by natural events. Groundwater can react with chalk and limestone to produce carbon dioxide that displaces the normal air in a confined space. Many of the dangers involve your head. There is danger to your nose in bad air, to your ears in noise, to your eyes in flying particles disturbed by your unexpected presence, and to your head itself under low ceilings and falling debris. The fact that you are confined and your movements are limited also makes accidentally touching live wires and sharp protrusions more likely.
Bystanders and noninvolved workers should be kept at a distance from confined, potentially dangerous sites by barriers. One of the saddest statistics about accidents in confined spaces is that about 70% of the victims are people who tried to rescue trapped workers. Sometimes they are Good Samaritans who have no idea of what they are getting into and have never been trained to rescue trapped colleagues. It is good practice for contractors to notify local, trained emergency crews of the conditions of potentially dangerous sites. Those crews have the right rescue equipment too. It's not just a length of rope somewhere in the back of the pickup. There are others in danger from your site. At the end of the day, make sure the public is kept away; that public could contain nosy adults or curious children. Are the entrances secured? Is the fencing around the site strong enough? If you have made excavations, are they covered or fenced off? Have all of the machines and power sources been immobilized? Have all of the flammable items been taken away and securely housed? Supplying acceptable air to a confined space is not difficult. General Equipment Company's EP8 portable electric air-ventilation blower, for example, will supply air at construction sites. It can remove toxic and noxious gases from sewers and clean the air of vaults and tanks. An added advantage is that a blower like this also can keep workers cool in trenches, and there is evidence that their productivity will be as much as 25% higher because of that. This blower is powered by a single-phase electric motor rated for continuous service (0.33 hp) from either a grounded 110 AC outlet or an AC electric generator of suitable size. "We recommend that, whenever possible, blowers should run on a continuous basis," suggests Dennis Von Ruden, president of General Equipment. Obviously workers will not enter a confined space until the oxygen level is within acceptable limits, and with continuous ventilation, that oxygen level and the atmospheric conditions will be maintained safely, with only minor fluctuations." For safety equipment related to your ears, be advised that the product that eliminates the most noise is not necessarily what you want. The discomfort of noise must be reduced, but the ability to hear instructions or warnings from other workers should remain. Concerning hearing protectors, Elizabeth Antry, director of marketing for Dalloz Safety, asserts, "The use of hearing protectors is like using goggles for welding. If a welder is working near dangerous flashes, the welder's goggles are needed to reduce the intensity of the light to a safe level, but they maintain as much vision as possible to allow the work to proceed. The worker does not put on a blindfold!" Similarly the employee working near high noise levels does not need to wear an ultrahigh-attenuation hearing protector that is just like a blindfold for the ears. Your favorite distributor should have all the information necessary for selecting the correct eye, ear, and nose protection for your workers.
"Protection is our first priority," explains Margie Wolfe, product manager for head and eye protection at North Safety Products in Cranston, RI. "If a protector is not comfortable, people will not wear it." Making sure that protective wear is comfortable is generally up to the manufacturer. "We design around the head form, for example, and after meeting government standards, we redesign to fit people," continues Wolfe. "We make prototypes with the basic design and do fit testing of males and females, people from different ethnic groups, people with varying head sizes and facial features. The three most important fitting zones for a human face are the bridge of the nose, the temples, and the apex of the ears. If you can design to fit all of those, you are successful in the end product." Two safety products that have been well accepted are hardhats and safety goggles, about which this must be said: Continue to wear them when necessary and select types that are adequate for your work. There is no reason today why they should not be both effective and comfortable. "One reason why hardhats receive little attention is that they are frequently treated as items purchased mainly with price in mind rather than as a head protection system that could save somebody's life," cautions Bill Newcomb, also a product manager at North Safety Products. "Check the safety of your hardhats. Suspensions can age and begin to crack, tear, or fray. Hair oil and materials in the environment can begin to affect the elasticity and strength. Baseball caps, skullcaps, and similar items should not be worn under the helmet because they reduce the space between the head and the skull, limiting the protection. Also, some caps have buttons, eyelets, and other features that could harm a worker if an impact occurs." Frequent contributor Paul Hull writes on construction and environmental topics for several international magazines. GEC - January/February 2004 |
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