Moffat Pipe, Inc. (MPI), based in Wake Forest, North Carolina, installed 320 linear feet of 5×10 foot cast-in-place concrete culvert pipe through the neighborhoods of Raleigh, North Carolina.
The storm-sewer installation was part of the Carolina Pines Dam Rehabilitation Project for the City of Raleigh Storm-Water Division.
Cast-in-place pipes and culverts present several challenges for contractors performing the installation work. Not the least of which is keeping workers safe in the pipeline trench that generally needs to be kept open and exposed longer than traditional precast pipe.
Compounding that challenge for MPI was that the new pipeline ran directly through a portion of Raleigh’s residential neighborhoods where active shoring with low vibration adjacent to existing structures was needed. And, “North Carolina DOT has some very strict requirements for shoring,” said Keith Moffat, one of the officer’s of MPI. “That usually leaves only tight sheeting or Slide Rail—systems the state considers ‘active shoring’—as viable options for shoring excavation projects within NCDOT right-of-ways encroachment agreements.”
Slide Rail is a component shoring system comprised of steel panels (similar to trench shield sidewalls) and vertical steel posts. Efficiency’s versatile system can be used in a variety of configurations, such as small four-sided pits; large unobstructed working pits as big as 50 x 50 ft. with Efficiency’s ClearSpan™ System; or in a four-sided or linear Multi-Bay™ configuration to install length of pipe over 40 feet.
Efficiency’s team of Slide Rail experts recommended a five-bay, Linear Multi-Bay™ Configuration which provided a long and wide working area to cast-in-place the large culvert, but still met the engineer’s requirement for “active-shoring” on the excavation.
Each of the five bays utilized 16- to 20-fot long panels, which when put together created a 96 feet long, 22 feet wide space to cast-in-place 84 feet of culvert at one time. Another advantage of Slide Rail? After the trench is backfilled around the culvert, the system components can be removed, leapfrogged forward along the pipeline, and reinstalled. MPI put the system—with all the same Slide Rail pieces—in the ground only four times to complete the 320 feet of new culvert pipe.
MPI also built two structures to go along the pipeline: a dissipater pad and a concrete inlet structure.
“Slide Rail really isn’t new around here, but I still meet engineers and contractors who’ve never seen it used before,” added Moffat. The Slide Rail I’ve worked with in the past has been the German-designed system with the big rigid cross members. The Efficiency Slide Rail is so much easier to work with compared to that,” Moffat concluded.
MPI anticipated that they would be using Slide Rail extensively in the future, so they purchased the entire system from an Indianapolis-based trench safety equipment distributor and requested that Efficiency Production paint the Slide Rail panels red, MPI’s corporate colors.
Excavators used by MPI were a John Deere 350D and a Deere 200C Excavator, plus a Deere TC62 Loader.
Moffat Pipe, Inc. specializes in water main, sanitary sewer and storm sewer installation and repair. Moffat has experience serving a variety of customers from schools, businesses and municipalities to commercial developers and heavy highway contractors.
By James McRay, Director of Marketing & Media for Efficiency Production, Inc.; contact James at [email protected].
A look back at MPI’s $1.25 million Dam Rehabilitation project
Cast-in-place pipes and culverts present a greater safety challenge as the pipeline trench generally needs to be kept open and exposed longer than traditional precast pipe.
The new pipeline is running directly through a portion of Raleigh’s residential neighborhoods where active shoring with low vibration adjacent to existing structures is required.
Efficiency recommended a five-bay, Linear Multi-Bay™ Configuration which provided a long and wide working area to cast-in-place the large culverts.