SHELLY & SANDS Installs Deep Sewer as Part of Major Highway Project in Ohio
Construction, construction, construction. Road construction as far as the eye can see. This is what residents in Columbus, Ohio, think when they travel practically anywhere. And due to the multi-year Interstates 70/71 Columbus Crossroads project, many freeways downtown will be under construction into the next decade.
With a civil project as large as the 70/71, a lot of the construction is not just road paving and bridge reconstruction; it is the installation or rehabilitation of underground utilities such as the miles of pipes for gas, water and sewers. Though perhaps a little less high-profile, these out-of-sight infrastructure projects are just as important.
Taking on one of these behind-the-scenes — though no less extraordinary — infrastructure projects was SHELLY & SANDS Inc. (SSI), based in Zanesville, Ohio. Founded in 1944, SSI serves eight major markets in three states and paves more roads in Ohio than any other company. Additionally, SSI has nine aggregate operations with extensive reserves numbering in the thousands of acres. SSI was low-bidder on an ODOT project to install a sewer system that diverts water from a large existing sewer line through four hydrodynamic separators that clean storm-water runoff before it is discharged into the Scioto River.
This was not an easy excavation project. It was in fact, four different excavation projects; each a different depth; some with different soil conditions; some with existing crossing utilities to navigate; and each having different sized pipes, structures, and/or manholes to install within. Complicating matters further was that the Best Management Practices (BMP) sewer project needed to be installed over a length of one block that was bordered narrowly between a western section of the I-70/71 corridor and an apartment building.
No Easy Solution
All four excavation points were deeper than 5 ft and required a trench protection system per OSHA regulations. “The first thing we considered were trench boxes; possibly using the equipment that we had in our fleet or we could easily rent,” said Brian Snode, SHELLY & SANDS’ Project Superintendent. “But we realized with the soil conditions and the existing utilities that were in the ground, plus the surrounding buildings; dropping in a box just wasn’t going to work,” he said.
“Also, with the highway and the apartment on each side, we realized we couldn’t vibrate in any sheeting or drive-in a lag wall,” Snode continued. “So, when we got down to it, really the only thing that would facilitate our need was a dig-and-push shoring system,” he said.
“Dig and Push” is a process most commonly associated with installing a Slide Rail System. Slide Rail is installed by sliding steel panels (similar to trench shield sidewalls) into integrated rails on vertical steel posts – an outside slotted rail first, then an open-face rail on the inside – then pushing the panels and posts incrementally down to grade as the pit is dug.
Calling for Reinforcements
Snode, however, had little experience with Slide Rail Systems. Needing help, he contacted his friend Jeff Riddle at Baker Corp. for some ideas. With over 20 years of shoring experience, Baker Corp. carries a full line of shoring equipment, including: Slide Rail shoring, steel and aluminum trench shields, hydraulic shoring, and road plate.
“We’ve worked with SSI many times before, and have a good relationship with the company and with their personnel,” said Riddle, Baker Corp.’s Branch Operations Manager. “So after looking at Brian’s project parameters, I knew that an Efficiency Production (manufactured) Slide Rail System would work; maybe the only thing that was going to work.”
Efficiency Production, a Trinity Shoring Products company, offers versatile trench shielding and shoring systems that are designed for safe and cost-effective installation of utility systems and infrastructure improvements.
Added Snode, “When Jeff started showing us how Efficiency’s Slide Rail System works, and the versatility of the system to change depending on ground conditions, well it was refreshing to see that they had a different shoring option for us,” he said.
However, it wasn’t just the contractor that had to be convinced on the effectiveness of the Slide Rail System. Snode and Riddle also needed to convince ODOT that it would work in the difficult site conditions, and meet their safety requirements. “We went over the entire installation and removal process with ODOT; how Slide Rail actually works and how it meets their safety guidelines for underground construction,” said Riddle.
Slide Rail is considered a positive shoring system. It maintains constant pressure against the sides of the excavation and requires no over-digging. This prevents possibly undermining or disturbing the surrounding foundations of buildings, roads, or other structures. A positive shoring system is a critical requirement for approval from most states’ Department of Transportation — including Ohio’s — for any underground construction.
Sufficiently assured that Slide Rail met all safety requirements, ODOT gave SSI the green light to begin work on the new gravity-flow sewer. They started from bottom to top; or downstream to upstream; or literally from the bottom of the hill at Short Street to the top of the hill at 2nd Street.
Pit 1 reached down 32 ft to uncover and reroute an existing sewer line. Utilizing the same Slide Rail components from the first excavation, Pit 2 was dug and shored for the installation of the four deep precast sump manholes which contain the hydrodynamic separators.
Pit 3 widened and lengthened the shored space just by adding a few more Slide Rail components, which allowed SSI to install inflow and outflow vaults and four 18-in. intake/outtake lines. “That’s where the manifold separates the water through the four deep sump manholes and through the screening process to clean it before it reenters the new piping that we built into Short Street,” Snode explained.
Lastly, Pit 4 was excavated for an 18 x 11 x 28 ft tall precast chamber which intersects a 96-in. existing storm sewer and diverts the flow through a more conventional 42-in. line down to the treatment structures. The fourth pit — the largest of the four excavations — was shored with a 29 x 38 x 32 ft deep ClearSpan configured Slide Rail System.
“Jeff and I looked at the ClearSpan pit at least eight times and actually had to redesign it on the fly,” said Snode. “Because the big 96-in. line was not in the exact location indicated in the plan, plus everything was right in the middle of the street. It was a challenge,” Snode conceded. “But we were able to overcome all of that because of the flexibility of Efficiency’s Slide Rail System.”
James McRay is the Director of Marketing & Media for Efficiency Production – A Trinity Shoring Products company.
Site-Specific Engineering for Unique Pipe Casing Installation
A Northwest Florida contractor was tasked to install 180 lf of a 60-in. pipe casing via boring. The storm water project required a linear run of 60-ft with a width of 20-ft and a depth of 16-ft in a sandy clay mixture that the competent person classified as Type-C-60.
The project site presented several challenges that could negatively impact the integrity of the adjacent structures. The excavation was located in line to a highway overpass involving a high traffic roadway and several highway overpass columns. The project would require a protective system that could properly accommodate a bore pit with a desired 41-ft open span work area for a 60-inch bore casing pipe running between the overpass support columns. Additionally, the protective system would need to address the possibility of dewatering the open trench and dealing with a deflection of the internal bracing.
The contractor called NTS to discuss a few protective options and after carefully reviewing some of the challenges, the contractor selected a site-specific slide rail and a hydraulic excavation brace combination system. Site specific engineered systems are designed for those unique and large-scale projects where poor soil conditions and adjacent structures are present. Site specific engineered systems offer a high degree of customization that allows for certain protective devices to be customized for unique applications. For the boring pit, it was determined that a slide rail system would be the most optimal solution that could provide a large open span work area if supported by an excavation brace. A slide rail system is a versatile protective underground system that can be used for a wide range of applications and paired with several modular components. A hydraulic excavation brace can be used as a four-sided application composed of adjustable hydraulic brace legs designed to support rectangular and square underground excavations. For those complex jobs, braces can be used in additional polygons such as 5 sided or 6 sided excavations. The contractor was extremely satisfied with the safety provided by the site specific engineered system, as it provided a practical solution during the pipe casing installation.