Efficiency Production’s Slide Rail System from United Rentals
shores deep trench along Des Moines I-235 reconstruction

The Iowa Department of Transportation is giving I-235 in Des Moines a complete $429 million multi-year makeover including: utility relocation, bridge replacement and rehabilitation, interchange reconstruction, and mainline paving.  The project began in 2002, and will not be completed until 2007.

2005 Keo Way Interchange Project

The six year project is phased to allow the maximum amount of work per construction season, with minimal delays and inconvenience.  There are nine projects ongoing in 2005, including the Keo Way Interchange.

Herberger and United Contractors, Inc.—a joint venture–are the primary contractors working on building a new westbound ramp and bridge over Keo (Keosauqua) Way in 2005.  Part of the Keo Way Interchange project is the $1.8 million installation of a new storm sewer pipe which the joint venture has subcontracted to Peterson Contractors, Inc. (PCI), Heavy and Highway Contractors headquartered in Reinbeck, Iowa.

New Storm Sewer Installed 30 ft. Deep in Right-of-Way

PCI is tapping into an existing 54 in. storm sewer line and diverting flow to another storm sewer with excess capacity.  They are installing 600 ft. of new 48 in. concrete pipe at a grade of 30 ft. deep; plus they are installing two RA49 Modified Junction Boxes for utility access.  The new pipeline is running west along I-235, about 21 ft. from the highway’s shoulder.

Deep Grade Poses Challenges for Shoring Trench

The deep grade and limited space in the highway’s right-of-way posed some challenges for shoring the trench.  “Normally, we would use double-stacked trench boxes, but after evaluating the soil conditions and determining that it is very wet C-60 type soil, we quickly realized that trench boxes would not be the best option,” says Doug DeSchamp, PCI’s Supervisor on the project.  “We also considered open cut, but again, the soil conditions wouldn’t allow that either.  We actually tried a test bench, but it quickly collapsed, and we lost part of the road’s shoulder.”

Efficiency Production Slide Rail from United Rentals Offers Solution

Doug Clark, Project Engineer for PCI, then contacted Eric Juhl at United Rentals-Trench Safety in Grimes, Iowa, for shoring options.  “We talked about the possibility of driving sheeting with tie-backs, but the very wet soil condition and pipe depth made that option very expensive,” explains Juhl.  “I then suggested an Efficiency Production Slide Rail System, which would be much more cost effective, and could easily handle the depth and soil-conditions with a triple-rail post system,” Juhl added

Slide Rail with Triple-Rail Post Perfectly Suited for Deep Excavations

Efficiency Slide Rail is a component system comprised of steel panels and posts.  The universal system can be used in a variety of configurations such as a four-sided pit or linear-bay application.  Slide Rail is installed simultaneously as the trench or pit is excavated by sliding the panels into rails on the posts, and 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.  Slide Rail posts have either a double or triple rail which telescope panels to required depth.

In a linear multi-bay configuration which PCI is utilizing, Efficiency-specified spreader pipes are pinned-in-place to a set of parallel beams with rollers that slid down slotted rails on the inside of two linear posts, providing the cross-trench support. 

Efficiency Production Inc. Director of Engineering Mike West noted that, “Efficiency’s Slide Rail System is well-suited for a dig 30 ft. or more because the triple-rail post system keeps side panels to a manageable weight.  Contractor’s can still install and remove the system with trackhoes and equipment they typically have in their fleet.”

Contractor Progressing Well with Linear-Bay Configuration

PCI rented a four-bay linear application slide rail system from United Rentals.  Three bays are 16 ft. long, and the fourth 14 ft. long.  They are using 6 ft. spreader pipes on the 1 ft. wide x 11 ft. tall parallel beam spreader assembly for a total trench width of 8 ft.

The linear-bay configuration allows PCI to install an 16 ft. length of 48 in. pipe in the front bay of the four-bay system while simultaneously backfilling and removing previously installed bays at the back of the trench.  The slide rail then can be leap-frogged for repeated use.

Efficiency Production’s Slide Rail is unique in that it is installed and removed incrementally, which allows the trench to be properly shored throughout the entire installation or removal process, always protecting workers from a trench wall collapse.

Because DeSchamp and his crew had never used Slide Rail before, Efficiency Production, Inc.’s Slide Rail Installer, Greg Ross, assisted with the initial installation and trained PCI’s crew on how to properly install the Slide Rail System.  “Our first couple days we went a little slower as we learned how to use the system, but now we are going much quicker,” commented DeSchamp. “We’re still on a learning curve, but we are meeting our schedule and have doubled our production since the beginning of the project.”

PCI anticipates connected to the west storm sewer by mid-October 2005. Bart Petersen is PCI’s project manager.  The pipe layers are using the following equipment to install the new pipe:

• 235D Long-Reach Caterpillar Excavator

• 330C Caterpillar Trackhoe

• Linkbuilt 110 ton Crane

• IT62A Caterpillar Front-loader

• Two - 740 Off-road Caterpillar Dump Trucks

Peterson Contractors, Inc. has been in the heavy and highway construction business since 1964.  They are proud members of Associated General Contractors (AGC) and AGC of Iowa.  Construction services performed by PCI include heavy earthwork and specialty construction. In addition to office personnel and engineers, PCI employs 50 to 350 construction craft-persons, depending on the season.

	Efficiency Production, Inc. Linear Slide Rail from United Rentals Trench Safety allowed Peterson Construction, Inc. (PCI) to install a new storm sewer pipe only 21 ft. from the shoulder of I-235!
Reaching a final grade of 30 ft. is no problem–even in very wet soil–with the help of Efficiency’s Slide Rail System with triple-rail posts.	The four-bay linear application slide rail system rented from United Rentals Trench Safety allows PCI to install pipe in the front bay of the four-bay system while simultaneously backfilling and removing previously installed bays at the back of the trench. The slide rail then can be leap-frogged for repeated use.