July 2010: Feature Story

Shore Is Safe
Trench Boxing and Shielding Safety Begets Productivity
By Jason Morgan

Few and far between jobs and increased bid competition can make cutting corners easy, but seasoned contractors know that a utility construction jobsite works best when all the gears are properly maintained and greased. Perhaps the greatest gear is safety. When your crews are working with safety as the No. 1 priority, your most valuable asset — your employees — are protected and you’ll stay productive. One of the best tools for jobsite safety is trench shoring.

By definition, the trench box or shield is designed with safety in mind. But with safety comes efficiency and productivity. Not only do you comply with OSHA safety standards when using shoring, but it gives your crews a sense of security that lets them do their job safely.

“Choosing improper equipment is a shortcut that can’t be taken,” says Robert Kundel Sr., President of Kundel Industries, a 30-year construction veteran, a 20-year equipment designer and a sponsor of the “Everybody Deserves to Go Home at Night” Web site www.ditchdigging.com. “Most people believe that shoring is only for protection, but they’re wrong. Shoring allows rhythm and boundaries and this enhances productivity and increases profits.”

“Contractors simply do not have to excavate as much earth when it is possible to cut trenches entirely vertical because they are using trench shields, slide rail or shoring,” adds James McRay, Director of Marketing and Media for Efficiency Production Inc. “It’s not the fanciest technology, but it’s certainly more productive than having to slope a trench to the correct angle of repose, which could require removing as much as three times as much soil. Remember, the less dirt you take out, the less expense in backfill material that you have to put in.”

The most dangerous shortcut one can take on the jobsite is not using a trench box or shield at all. Even worse are the contractors who have a shield onsite to ward off OSHA officials, but never put it in the ground. Regardless of how safe the trench looks, a deadly collapse can happen in an instant.

While you’re only required to use a trench box or shield when the trench is deeper than 5 ft (4 ft in some states) according to OSHA, good common sense says that jobsite conditions dictate when to use a trench box.

“Soil conditions of the excavation will always dictate whether a protective system is necessary,” says McRay. “When digging a trench in heavy clay, for example, if the banks collapsed — even at 3 or 4 ft — it could impose serious injury to any worker caught under the falling dirt. That is why it is critical that every contractor has a Competent Person [CP] present on the jobsite who can assess dangerous ground and soil conditions and that the CP has the authority to mandate a protective system to be used even in an excavation less than the OSHA mandated depth.”

OSHA Knows Best

In 1999, a four-year-old girl named Jackie Moore fell into a trench that had just been dug in her backyard and died when the trench collapsed. Last year, the Massachusetts Department of Public Safety passed a new law that requires trenches to be covered when not worked on. Under the Massachusetts guidelines for excavation and trench safety, section 14.04: Protections for the General Public, provision 2 states, “Access to unattended trenches opened during construction on a public way shall be restricted by covers or barriers.” It’s a law that you’re likely going to see in more states, according to Al Mackenzie, Shoring Representative for American Shoring Inc.

While there are specific regulations from individual states that every contractor should know by checking their local laws, you can avoid OSHA fines by watching out for several common misuses or shortcuts. Not only does that affect your bottom line, but it also puts your crews’ well-being at risk.

One of the more complicated gray areas is the use of road plates to extend shoring or shielding.

“A lot of contractors will take an 8-ft tall trench box and put it in the ground, but they have to go 12 ft in the ground; so they’ll take a road plate and shove it alongside the trench and trench box to try to extend the trench box,” explains Mackenzie. “The problem is that the trench box side panel was designed to secure the earth of an 8-ft trench, but with the road plate alongside of it and an additional 4 ft of earth above it. That’s additional pressure on the trench box and its spreaders, which they weren’t designed for.”

Why is this practice more common on jobsites than it should be? Money. It’s cheaper to rent a road plate at $100 a week than another trench box at $500. It’s hard to spend money when profit margins are razor thin, but safety equipment is not the place to cut costs.

Drag boxes are a popular option for utility construction. You can use a drag box one of two ways: 1) You can dig in front of it and the pull it down to grade or 2) you lift up on the front of it and drag it forward then push the front back down again, if you’re on stable soil.

Another, perhaps more dangerous, situation in which a contractor might cut corners is when he is crossing under an existing utility.

“You’re typically working in a previously dug ditch and so the ground around it could be saturated,” says Kundel. “In that type of situation, some people might not want to put the investment into the equipment and they’d go outside the box into the most unstable areas. In reality, they need a box or shield on one side of the utility and one on the other side. The flexibility of a shorter utility box is good for that situation.”

In addition to the larger issue of improperly using trench shoring, there are smaller, yet no less important, trench shoring safety factors to keep in mind. First off, if you’re working in a long trench, say one that’s over 40 ft long, OSHA mandates that you have a tied-off ladder every 24 ft, says Mackenzie. Another common fine is for missing safety clips or pins that hold the spreaders to the trench box. This is a problem common with boxes that have horizontal pin holes. It’s not uncommon for them to fall out.

Contractors also need to watch out for misuses of trench boxes. Be mindful of voids outside of the box that a person can fall into or get pinched in between the box and the banks. And always make sure you have the right tool for the job.

“Maybe the trench shield is rated to go to 15 ft in Type-C soil [the worst] and it is put in a trench 20 ft deep,” says McRay. “Trench shields are generally manufactured to withstand pressures beyond the listed depth rating, but that excuse will not fly with OSHA. And, a contractor also needs to remember that trench shields and shoring do not last forever. If a trench box looks a little dodgy, then it should probably not be used.”

Many manufacturers offer services to help you use their products safely and efficiently. For Kundel, the key to a safe, productive jobsite is to have a trench safety system that is flexible (and manufacturer backed) enough to custom fit your equipment to your job. It is important for equipment to be used with accessories that can adapt to changing job conditions. Planning and communication between user/designer/manufacturer is crucial to increase profits.

Efficiency Production would agree that productivity is all about planning, as the company provides engineering consultation and pre-bid CAD drawings and illustrations. Beyond that, Efficiency can customize a design for any trench shoring system. It also has two travelling NUCA Master Instructors who provide CP Training. Similarly, Mackenzie from American Shoring was actually on the road to another jobsite when he took the time to talk to UC.

Purchasing Power

Where you can save some green is in figuring if it’s better for you to rent or buy your trench shoring solution. Typically, the choice depends on the duration of the job. These days, many contractors don’t know when the next job is going to come around, so rental is the more popular option, but there are instances when you’d need a custom shoring solution or just want a good investment.

“Lowering costs, like operation and fuel, is huge ROI when talking about trench safety equipment,” says Kundel. “The future will require better matching of the equipment to the job, even to the point of purchasing custom equipment that fits only a particular job. Over-sizing an excavator just to lift the equipment increases fuel cost and lowers the ROI. The contractor that learns how to manipulate trench safety equipment by utilizing trench lining as well as box dragging and is willing to focus on sizing down his or her investment will earn the jobs and still make a profit.”

Some manufacturers, like Efficiency and American Shoring, offer a repair program. Efficiency has contractors send in their damaged or old trench boxes and they make repairs and have a professional engineer recertify the shield and provide new tab data, which can save a trench full of money compared to buying a brand new shield.

Another popular option, according to Mackenzie, is rent-to-own or purchasing pre-owned trench boxes. It can help save you some money and keep you safety compliant. Regardless of where you get your trench shield, box or custom shoring solution, the key to a safe, productive jobsite is the correct implementation of your system.

Jason Morgan is Associate Editor of Utility Contractor.

The ClearSpan Slide Rail
Shoring System Solution
By James McRay

To excavate the massive pit and install the slide rail components, Johnston used an 866E Koering excavator with a 3-yd bucket, a 330 Terex crane, a 108 Linkbelt crane with Lead and Drop Hammer to install opposite side posts and panels and a 7.8 Komatsu mini excavator.

Safety, Safety, Safety. For the Dow Chemical Co. — the nation’s largest chemical company — safety is the first, last and in-between consideration. Everything that goes on at its many worldwide facilities is looked at through the prism of safety.

The Dow Chemical Co. is in the process of installing a new 25- by 55- by 30-ft lift station at its Midland facility, which will hold surface run-off water collected through an existing 54-in. storm sewer line and will pump the water through a new 36-in. line to a recently built, 10 million gal above-ground water storage tank for future treatment.

To tap into the existing storm sewer line, the new concrete structure is to be poured in place 35 ft into the ground. To accommodate the lift station, the working pit dimensions needed to be over 60 ft long and 35 ft wide and had to stay open and properly shored for more than three months.

The low bidder for the project was Johnston Contracting. Owner and operator Lee Johnston has many years of experience working with Dow, inside and outside of its main facility. The project’s biggest safety challenge was properly shoring the large and deep working pit that would be open for a long period of time. Enter Efficiency Productions Inc.

Efficiency’s universal slide rail is a component shoring system comprised of steel panels (similar to trench shield sidewalls) and vertical steel posts. The highly versatile system can be used in a variety of configurations. In addition to the obstruction-free ClearSpan configuration, Efficiency’s universal slide rail can be configured into small four-sided pits or in a multi-bay configuration to install large tanks and structures or lengths of pipe over 40 ft.

Slide rail is installed simultaneously as the trench or pit is excavated by sliding the panels into integrated rails on the posts — either double or triple rails depending on needed depth — and then pushing the panels and posts incrementally down to grade as the pit is dug. The process is commonly referred to as a “dig and push” system. This allows the Slide Rail System to be installed simultaneously as the pit or trench is excavated to grade.

Sheeting is, by nature, a loud, long and cumbersome way to secure a large excavation, and it requires extra specialized equipment in addition to just an excavator. Johnston installed the entire slide rail system in 13 days, rather than the 30 days it would have taken to install an alternate shoring system like tight sheeting.

“If we’d used sheeting, we would have had double walers and cross braces,” said Johnston. “That would leave us with 12 penetrations to pour the concrete through and would take an extra month to finish.”

As it was, Johnston had on-site installation assistance from Efficiency’s slide rail systems Manager Greg Ross.
“We really had no problems installing the system. A big advantage of using an Efficiency system is that not having used slide rail before, Greg Ross was here a couple days to help us get started. That was a big help,” Johnston concluded.

James McRay is the Director of Marketing and Media for Efficiency Production Inc., based in Mason, Mich.

Coble Trench Safety Adapts Slide Rail System to Encompass Jobsite Change
By Tom Coble

The Conundrum

A contractor was repairing an existing storm drain system that had failed. The failure had caused a large sinkhole in a grocery store parking lot that had become a safety hazard for the grocery store. The contractor had classified the soil as C-60.

The central challenge for this project was that the sinkhole was growing and needed to be contained before the next rain would further wash out the sinkhole. The soil was exceptionally poor and would not stand upon excavation. Additionally, the contractor was not sure how deep the excavation would be down to the pipe. The contractor had estimated a depth of 20 ft would provide the necessary depth. The contractor’s main concern was completing the project as quickly as possible to minimize further damage.

The Solution

After the series of discussions, Coble Trench Safety Representative Richard Overman presented a pit slide-rail system to the contractor. The system would help to accommodate the soil raveling by providing proactive soil support as the panels are pushed ahead of the excavator’s cut.

The system installed quickly. Despite digging the system to the 20 ft of depth, the contractor had still not unearthed the pipe and reached the full depth of the system as designed. Overman was on the scene to help address the next steps.

After a brief meeting, a conventional steel manhole shield was identified as the necessary extension to the slide rail system, allowing the contractor to dig down to the pipe. The manhole shield would be lowered into the excavation using the existing system, without any need to remove the slide rail system or increase the installation time period. The project had a site specific plan and it was altered to include the conclusion of the steel manhole shield, within a few hours, to support the production schedule.