American Backhoe, Army Corps of Engineers, and United Rentals-Trench Safety Go to the Heartland for Native American Hospital Project  

 by Mike Fernandez  

Winnebago, NE. 5/2004 – The Army Corps of Engineers are managing the construction of a new health care facility for the Native American Tribes of Northeast Nebraska, Northwest Iowa, and Southeast South Dakota. Part of the project involved excavating adjacent to the new hospital building where many existing utilities, structures, and other limitations made a large diesel tank installation very challenging.  

American Backhoe Co., of Omaha, NE, an Environmental Contractor specializing in hazardous waste removal and containment, tank installation and removal, and utility installations, was contracted to excavate then install the 15,000-gallon fiberglass fuel tank measuring 36 ft. long x 8 ft. diameter. The tank will be used to fuel the health care facility’s backup generators.  

The south side of the 16-foot deep tank pit was specified to be within 8 feet of a concrete slab where all of the HVAC equipment was stationed. Just to the west of the HVAC equipment was a utility building that was also within 8 feet of the excavation. Inside of this 8 foot opening, between the pit and the aforementioned structures, was a water main that ran 6 feet down from the excavation. A concrete block retaining wall ran along the east side of the excavation and wrapped around partially on the south side as well. This wall was also about 8 feet from the excavation. To add to the challenge of the limited access on the site were nearby railroad tracks, traffic, and other existing utilities. Soil conditions were C-60 weak clay down to 8 feet with a high water table at 9 feet. 

The first obstacle to deal with was the size of the tank. A specific trench shielding system was necessary to insure that a clear unobstructed opening could be maintained that was at least 16 feet wide and 46 feet long. The second obstacle was the high water table. The clay was very dense and it caused the soil to rise up from under the shoring system. The material was coming from outside of the shielding system, which could have eventually caused adjacent structures to shift. 

“We overcame the first obstacle by working with Todd Hayes of United Rentals-Trench Safety in Council Bluffs, Iowa,” stated American Backhoe Superintendent, Wally Kanne. “We have worked with Todd in the past on selecting shoring systems for typical trenches and pits and for the unusual as well,” he added. American Backhoe had used beam & plate in the past and had overdriven sheet piling but Hayes informed them on the advantages of Efficiency Production’s Slide Rail System in this type of application. “Todd sold us on the system and the advantage of working with a distributor such as United Rentals-Trench Safety who have experience installing slide rails on a vast number of projects with various applications, and who have this type of equipment available within 1 to 3 hours of the project,” declared Kanne. The job held a tight schedule and if a problem or change would occur on a project of this nature American Backhoe could not wait for equipment to come in from another dealer or manufacturer hundreds of miles away. The liquidated damages would cut into any of the expected profits on the job.  

In overcoming the second problem, American Backhoe dug one of the slide rail bays down to grade and installed a pump in the corner. They were successful in diverting the water to this end of the system throughout the rest of the project. 

Choosing the System

A three bay Linear Slide Rail system with 16’ long panels on the sides, linear posts and open-face corner posts, and more 16-foot panels on the ends to complete the rectangular configuration was used to shield the 52-foot long pit. Efficiency’s open-face corner posts are unique in that they allow for a margin of error; they are forgiving when inserting panels when the system is not truly square. This minimizes post and panel binding and facilitates the process of getting the system down to finished grade! Efficiency’s ClearSpan tie-back waler system was used so the parallel beam spreaders could be pulled out for a continuous unobstructed opening once the entire system was set! “Efficiency’s ClearSpan Slide Rail System is by far the best tie-back system used in slide rail applications that we have seen,” declared Kanne. “The other systems require us to have a welder on site and there is a tremendous amount of time spent in welding the linear posts to the beams used to prevent the system from cantilevering.” He added, “The tie-back design with a C-Clamp would allow multiple slide rail bays in both directions without working outside of OSHA’s regulations.”  

A safety officer and a representative from the Army Corps of Engineers were on site overseeing the installation. Every step of this installation had to be compliant with all OSHA’s regulations. “This system allowed us to work in that capacity!” said Kanne.

 Alternative to Sheet Piling

 If the owner would have allowed sheet piling American Backhoe would have had to pay a sheeting contractor to mobilize a crane to install the sheeting. They would have to get sight specific engineering from a Registered Professional Engineer with a Nebraska stamp. “We also would have had a tremendous amount of labor invested in welding a waler system to eliminate the cantilever at the top of the sheeting,” said Kanne. Fortunately, sheeting was not allowed on the project since the existing hospital building was located just to the west of the excavation site and heavy vibration associated with installing sheet piling would cause structural damage. “The Slide Rail is more cost effective…and the system is much faster and smoother than the other options out there,” said Kanne.

American Backhoe was able to install and remove the system with the standard equipment used on excavation sites; a Komatsu 400 excavator and a John Deere Front end loader. Dan Veskerna of American Crane secured the subcontract to lift and place the tank into the pit. “We finished the schedule on time,” said Kanne, “and I attribute this to having good people to work with, and the right equipment on site!”  

The United Rentals-Trench Safety Division has rented Efficiency’s Slide Rail System to contractors for many other successful projects and continues to invest heavily in stocking the system in dealerships for maximum availability throughout the U.S.