Michigan UP Excavation Challenges

November 2010, Vol. 65 No. 11
The biggest challenge wasn't Sault Ste. Marie’s historic buildings or Indian Burial Park, but the price of backfill.

Efficiency’s Universal Slide Rail is a component shoring system comprised of steel panels (similar to trench shield sidewalls) and vertical steel posts. The versatile system can be used in a variety of configurations, such as small four-sided pits; large unobstructed working pits as big as 50 by 50 feet with Efficiency’s ClearSpan System; or in a linear Multi-Bay configuration to install pipe lengths of more than 40 feet.

After returning from Utah, Bacco rented a slide rail ystem configured in a 6-bay, Linear Multi-Bay application.

A slide rail systems 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 – then pushing the panels and posts incrementally down to grade as the pit is dug; a process commonly referred to as a “dig and push” system.

Cost savings
After an initial learning curve, Wentland said that they were typically getting in 80 to 100 linear feet of eight-foot long, 18-inch diameter reinforced concrete pipe per day at an average depth of 22 feet. “This (slide rail) really is the perfect shoring system for this type of soil,” explained Wentland. “The heavy clay we were encountering is always moving, flowing. With this system, the panels seal off the trench from the dirt that’s constantly shearing in. It can withstand a lot of soil pressure,” he said.

Bacco is moving east to west, along E. Water Street and East Park Place, across from the opening to the Lake Huron or “downriver” locks. Parts of the new sanitary sewer line was installed just below the old line which runs down the center of the two concurrent roads. Here again, slide rail shows its advantages and versatility. “Just consider, if we used double stacked trench shields, we would still need to cut outside the box. This slide rail systems allows us to keep the trench as narrow as possible -- not even eight-feet wide -- and that means less expensive backfill and more profit for us,” Wentland concluded.

Bacco is using a CAT 385 Excavator on the front end of the trench to excavate and install the slide rail components. They are using a CAT 345 Excavator on the back end to backfill and remove the system, plus a CAT 966 Front Loader.