Grading and Excavation Contractor

Contractors face a number of challenges on any given job site, especially when that contractor is working on the largest, most expensive job in company history. Trucco Construction Co. Inc., a contracting firm based in Powell, OH, found itself in this exact situation in September of 2004 after having a $16.2 million bid accepted for a sanitary sewer line project in its own back yard, Delaware County.

Founded in 1990, Trucco handles a variety of construction projects for both private and public entities, from site development to road building to utility installation. With few exceptions, the company has the internal resources to handle every aspect of the jobs on which it works. The complexities of the Delaware County project required the company to tap into several of those resources.

The company decided to explore the option of a hydraulic hammer to break out the rock.

Generally, the rock was broken out at a depth of 2 or 3 feet at a time.

The project called for the construction of a four-mile sanitary sewer line to serve a rapidly developing 21-square mile area in Delaware County. The specifications involved connecting the new sewer line to the existing sanitation system. Among other things, this new extension required the construction and installation of multiple tunnels going underneath the Olentangy River.

If boring holes for 500-foot-long underwater micro-tunnels and digging miles of pipe trenches weren’t going to be enough of a challenge for Trucco, there were environmental issues to contend with as well. That’s because this particular stretch of the Olentangy falls within a 22-mile tract of the river that is designated as scenic, one of 15 such waterways in the state of Ohio.

Trucco went into the job aware that they would be held to a high standard regarding erosion control and disturbance of the streambed along the project. Along with the potential effects to the quality of the river, which is continuously monitored by several organizations, Trucco also had to consider how varying construction methods might affect the structural integrity of several million-dollar homes in the area.

Two miles of the work area along the river were made up of sand and gravel. The other two miles consisted of solid rock. For the sand and gravel portions, Trucco used a large excavator to dig trenches where sewer pipe would then be laid. But in order to excavate the trenches in the other designated locations, Trucco first had to remove large quantities of rock.

“Our original intent was to blast out the rock with dynamite,” says Trucco project manager Nick Clarke, a four-year veteran of the company. Trucco spent almost $50,000 to complete an extensive preblast survey of the area before getting started. Although the idea of blasting around the Olentangy was marginally accepted at best, Trucco did have the necessary permits to go ahead with the blasting operation.

Once it came time to actually begin dynamiting, however, Trucco found it difficult to keep boreholes open in the overburden of the rock, and several attempts to blast were unsuccessful. Trucco briefly considered alternative methods to make blasting possible, but they were deemed too expensive and more importantly, these options would have held up the production schedule of the excavating crew.

The production rate on the job was certainly a concern, given the 18-month time frame for overall completion of the project. Trucco decided to explore the option of using a hydraulic hammer to break out the rock. “We did some calculations and a little bit of experimentation with the hammers we had on hand,” says Clarke. “We found that the rock was breakable. We just needed a larger hammer that could get our production in line with our schedule.”

Trucco began shopping for a hammer. And after comparing a few models from various manufacturers, Trucco decided on the Atlas Copco HB 7000 hydraulic breaker attachment. “Just looking at the weight and breaking force of the HB 7000 made it appealing,” says Trucco equipment manager Eric Berenstein. “And we thought that if we’re going to get a hammer for this project, we should get the biggest available.”

With a service weight of more than seven tons, the HB 7000 is the largest and hardest-hitting hydraulic breaker in the world—exactly what Trucco was looking for. In September of 2005, local Atlas Copco dealer Columbus Equipment sold Trucco the HB 7000, along with an 80-ton Komatsu excavator as the carrier for the breaker.

Trucco needed to dig trenches to an average depth of 20 feet throughout the project. For the areas of rock, the top 10 feet of the trench cut was overburden comprised of granular material. The overburden was removed by an excavator, which was closely followed by two or three trench boxes. Once the crew excavated a given section down to the bedrock, they would bring in the HB 7000.

In most cases rock was broken out to a depth of 2 or 3 feet at a time across the width of the trench. After the excavator removed the broken rock, the HB 7000 would go back in for more breaking. This process continued until the subgrade was reached. The crew then placed gravel on the bottom of the trench and laid pipe. Meanwhile, other members of the crew continuously backfilled the area where pipe was already installed. The entire procedure was repeated multiple times per day, depending on the chosen production rate.

According to Clarke, it wasn’t uncommon for the HB 7000 to break 100 lineal feet of rock in one day. Factoring in a 10-foot depth and an eight-foot trench width, the breaker’s production amounted to approximately 8,000 cubic feet of rock per day. “Given the opportunity, the hammer could probably break more than twice that by itself,” says Clarke. “But obviously with it being tied in with the pipe-laying operation, it’s not being used 100% of the time.”

While breaking wasn’t originally the intended method for the rock trenching operation, it did turn out to be an economical solution for Trucco. “There were several variables to consider,” says Clarke. “The pipe itself is very expensive. And we needed a large crew at a cost of about $1,500 an hour to do the job. But all things considered, it was just as affordable to break the rock than it would have been to blast. The hammer gained incredible production for the dollar value.”

“We’ve been impressed by zero downtime,” says Berenstein of the breaker’s durability. The HB 7000 features a special wear package, including an automatic lubrication system and components that self-adjust the breaker’s output power in changing conditions, thus preventing unnecessary strain on both the breaker and its carrier. “It’s been maintenance free,” adds Clarke.

Berenstein attributes much of Trucco’s success with the HB 7000 to the training the company received at the time of purchase. “We received both management training and hands on operator training from the Atlas Copco folks,” says Berenstein. “The support was the best I’ve ever seen.”

Personnel from Atlas Copco and Columbus Equipment assisted Trucco in making sure the breaker was set up properly. “The presentation and follow-up in the field was outstanding,” says Clarke. “The information they supplied was so thorough that it genuinely surprised me. It even caused us to re-evaluate how we maintain our other hammers.”

Keeping the project on schedule for its anticipated completion in June of 2006 was a necessity to the future residential and commercial development in Southern Delaware County, which includes proposed sites for a college and a hospital. For Trucco, it was also about upholding a reputation as a company that will get the job done on time and get it done right.

“We take a lot pride in our business and set high standards for ourselves,” says Berenstein. “A big part of that commitment is doing what’s necessary to deliver quality work on every job.” And by bringing in the world’s biggest breaker to take on the company’s biggest project to date, Trucco turned a big challenge into a resounding success.

GEC - May 2008

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