Like many other communities across the country, Springfield, Ore., is upgrading its aging sewer infrastructure to keep pace with growth and new development. This means replacing miles of sewer lines and manholes, and installing new lift stations. One recent lift station installation project was unusual due to the sheer enormity of the structure: a pour-in-place behemoth measuring 35 by 29 by 37 ft. (10 by 8.8 by 11.2 m).
Two bores and pipe runs were needed for the new lift station to handle the increase on the sewer system from a new hospital. Safely installing the structure posed several unique challenges as the 41- by 35-sq.-ft. (3.8 by 3.2 sq m) pedestal for the structure needed to be set at a final grade of 41 ft. (12.4 m) deep.
for Shoring Specs
Emery and Sons of Stayton, Ore., won the job as low bidder by working closely with Nigel Guisinger of D.P. Nicoli Inc. — a shoring and piling supplier in the area — to design a shoring system that used Efficiency Production’s Universal Slide Rail System in the ClearSpan configuration.
“We were competing with three other contractors for the job, and I’m sure we would not have been low if we didn’t bid with slide rail,” said Tim Janesofsky, Emery and Sons’ estimator and project manager.
Slide Rail System’s
Up to Challenge
Guisinger met with Emery and Sons and concrete subcontractor Marion Construction, and settled on a final ClearSpan system that was 46 by 50 sq. ft. (4.2 by 4.6 sq m) with a depth of 41 ft. (12 m); the largest 4-sided slide rail system ever designed, according to Efficiency Production Vice President of Engineering Mike West.
“We’ve always said that in theory, ClearSpan can have unlimited size, and this excavation proves that a 50-foot wide pit is not just theory,” said West. “Other manufacturer’s clear span configurations need to be installed with cumbersome cross-members. Only Efficiency’s ClearSpan system is never encumbered by cross-members at any time.”
’Dig and Push’ System Reduces Over-Excavation
Efficiency’s Universal Slide Rail is a component shoring system comprised of steel panels (similar to trench shield sidewalls) and vertical steel posts. The system can be used in a variety of configurations, in addition to ClearSpan such as small four-sided pits; or in a linear multi-bay configuration to install lengths of pipe more than 40 ft. (12 m).
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 — 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.
Custom Engineering, Design Standard
D.P. Nicoli Inc. worked closely with Hans Vermeulen, owner of J.M. Turner Engineering to come up with a final, stamped, site-specific shoring plan for the large pit. Two internal and one external waler were required to get the calculations to work out for the submittals. Guisinger then consulted with Efficiency’s West to design the custom walers.
There was a bore pit located on the south end of the large pit that also was shored with Efficiency Slide Rail.
Wayne Toney was Emery and Sons’ on-site foreman. His crew had installed Efficiency Slide Rail from D.P. Nicoli on numerous Emery and Sons projects and he has a very good working relationship with Bruce Ellis, D.P. Nicoli’s senior slide rail specialist.
“The nice thing about working with Wayne is that he has a lot of common sense as well as experience,” said Ellis. “He also really knows slide rail, so any problems that creep up when installing or removing the system are quickly dealt with.”
System Solves Limited Access Problems
The excavation site had very limited space to stage product, so deliveries were coordinated to keep excess product to a minimum. The pit was located just 30 ft. (9.1 m) off Harlow Road, a major five-lane arterial in Springfield. A senior center was only 75 ft. (22 m) from the pit on one side, and a driveway into an apartment complex was less than 10 ft. (3 m) from the other side of the excavation. The tight quarters of the excavation site eliminated the option of sheet piling. The disturbance created by the vibration or piling machine would have been very disruptive to the residents living next to the project.
Before starting to dig, Kirk St. Claire Welding was brought on-site to fabricate the custom ClearSpan walers. Two-in.-thick steel plates were welded to 24-in. (60 cm) by 162-lb. (73 kg) grade 50 wide flange beams. All welding and fabrication on the walers was inspected.
These beams were bolted to the Efficiency waler corners, which were used on the external and internal walers. St. Claire Welding also was called on to weld corner supports on the inside walers to help get the proper depth rating for the system.
Dewatering wells were installed around the parameter prior to digging. The top 12 ft. (3.6 m) were sandy clay, which turned to a very dense hard-packed cobble. The water table was around 10 ft. (3 m). An internal pump also was used to control the water in the work area.
Before actually digging the pit, the excavation was benched down the first 8 to 10 ft. (2.4 to 3 m). The pit was dug out with a Link Belt 290 excavating the inside, while a Komatsu 600 trackhoe loaded trucks and drove the slide rail posts and panels. After setting slide rail panels into the outside slotted rails of the posts down to 12 ft., the 290 was tracked out and a John Deere 80C was lowered into the pit to complete the excavation.
The remaining panels were installed into the two inside “open face” rails of the 32-ft. triple-rail posts to obtain the final grade needed for the lift station.
Efficiency Production’s Slide Rail 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.
D.P. Nicoli Inc. is a full service piling and shoring company founded 25 years ago by Dave Nicoli. Headquartered in Tualatin, Ore., D.P. Nicoli has branches in Seattle, Wash.; San Francisco; and Bay Point, Calif. The shoring and piling company services the western United States. D.P. Nicoli has been an Efficiency trench shoring distributor for seven years.
Efficiency Production Inc., provides a wide selection of standard and custom trench shielding and shoring systems. Efficiency’s products are designed specifically for safe and cost effective installation of utility systems and infrastructure improvements. All products are P.E. certified to meet OSHA and MIOSHA standards.
D.P. Nicoli Inc. is a member of the local NUCA chapter. Emery and Sons also is a member and Bill Martinak, Emery’s owner, is the current president.