A Hole in One: Bypassing Without Pumps in West Palm Beach
In February 2016, the West Palm Beach, Fla., office of Jacobs Engineering in conjunction with the City of West Palm Beach released a 48-in. force main sewer rehabilitation project for bid, a project that involved crossing a golf course owned by famed golfer Jack Nicklaus.
Formally referred to as “48-in. Force Main Cured-In-Place Lining Phase I” (project #91869198), the project’s scope included the installation of glass fiber reinforced cured-in-place pipe (CIPP) lining, disconnection and reconnection of feeder force mains, maintenance of flow bypassing, replacement of air release valves and vaults, and the installation of 48-in. plug valves for 5,700 ft of 48-in. pre-stressed concrete cylinder force main.
Bids were received in March 2016, and the project was awarded to Insituform Technologies LLC later that same month.
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To meet both the engineer and City’s specifications and requirements, many challenges had to be overcome in regard to the maintenance of flow bypassing. Because this was a force main bypass, there was a possibility that the existing pumps in the pump station could be used to push the flow to a downstream location provided that the existing pumps could overcome any additional pressure created by the temporary piping. With these considerations in mind, Sunbelt Rentals’ engineered bypass solutions team, national account manager and local sales personnel engineered a system that would meet the requirements set forth by the engineer and City, submitting their plan to the contractors prior to their bid submissions. Insituform then awarded the bypass portion of the project to Sunbelt Rentals Pump & Power Services.
Maintenance of Flow Bypassing
Jacobs Engineering determined that the maximum sustained flow the pump station could supply was roughly 30 mgd (20,833 gpm), and that the added pressure the pumps could absorb from the bypass piping could not exceed 12 psi (27.72’ TDH). In addition, the City of West Palm Beach also required a redundant pipe equal to the largest diameter of any pipe used for the maintenance of flow bypassing.
Insituform provided a line stop both upstream and downstream of the area of force main to be rehabilitated, giving Sunbelt a 36-in. flange to tie its piping system into to isolate the area. The Sunbelt system used both 36-in. ductile iron and 24-in. HDPE fittings at each line stop location, distributing the 30 mgd into three 24-in., HDPE temporary primary pipes and one HDPE temporary redundant pipe, all of which were fused together using T630 fusion machines. Sunbelt also installed 24-in. SST knife valves at either end of each 24-in. HDPE pipe as a precaution in case one of the pipes needed to be isolated and taken out of service.
Although the downstream location provided ample room for the footprint of the manifold system, access issues presented minor issues to work through. The upstream location, however, presented its own unique set of challenges. Limited to an area within parking spaces for a condominium complex, the upstream location necessitated a plan for local traffic, as well as how best to secure a safe work environment for employees and curious residents. Once these obstacles were overcome, a plan was put in place for the pipe route to allow the pipes to safely run approximately 5,900 ft (23,600 ft total with all four pipes) through the complex, across a Jack Nicklaus golf course, underneath a moderate-to-heavily traveled roadway, across a high voltage transmission property, and across and adjacent to a 45-ft wide retention canal.
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The four pipes also had to cross a moderately traversed roadway and across a high voltage transmission property, as well as across and adjacent to a 45-ft wide retention canal.
Following the Path of the Bypass
To maneuver the four HDPE pipes through the condominium complex, Insituform had another subcontractor grade approximately 400 ft and remove two sidewalks to provide a flat work space. To keep the area’s ever-present rain from creating an unstable work environment and causing project delays, Sunbelt also tapped into the expertise of its ground protection team to create a temporary roadway using MegaDeck industrial mats. This system paired two 7-ft x 14-ft mats to create a 14-ft wide roadway. All told, this area not only provided a place for the temporary pipe to rest, but also served as the main access point for all construction activities for the first 1,400 ft of the eastern portion of the project.
Once through the condo complex, the four pipes then had to cross three fairways and a lagoon before paralleling another fairway on the course. To span the fairways and minimize damage to the golf course, the Sunbelt team extended its MegaDeck system another 1,000 ft, allowing all construction equipment for this portion of the project access to both the bypass and CIPP activities.
To minimize disruption to employees and players on the course, the country club mandated that access to two golf cart paths and one maintenance road remain unaffected during construction. However, due to the number of irrigation utilities, the club would not allow any trenching for temporary pipes. To accommodate these requirements, Insituform tasked another subcontractor with building a temporary rock bridge over the four 24-in. HDPE pipes. To help protect the pipes and effectively provide access for heavyweight maintenance vehicles for the course, the pipes were encased in 30-in. steel pipes provided by Sunbelt. For the golf cart paths, Sunbelt also provided two heavy duty ADA ramps so that carts could maneuver safely over the pipes.
Following the golf cart paths, the four pipes then crossed a lagoon, traversing under a golf cart bridge. Once on the west side of the lagoon, the pipes ran parallel to another fairway, and the MegaDeck ground protection system was again used to provide access for construction-related activities with minimal damage to the course.
After crossing the golf course, the Sunbelt team then had to transition the four discharge pipes through a trench measuring 10 ft wide x 28 in. deep across Saratoga Road, a thoroughfare with moderate to heavy traffic.
Once in place, the trench was filled with “flowable fill” to encase the pipes, and temporary asphalt was installed to minimize impact on vehicular traffic. The four pipes then transitioned back above ground and through the high voltage property. In addition to the dangers associated with high voltage lines, it was essential that we maintain a stable and secure work space in this section, as it served as the team’s main construction area. Once again, ground protection was used to create a 70 ft x 42 ft work pad to maintain a stable work surface and prevent potential weather delays.
The final portion of the bypass’ path was the retention canal located at the westernmost portion of the project, and pipe placement posed some minor challenges to work through. Not all four pipes could be placed on the south side of the canal because it would not leave enough room for Insituform to perform its construction activities for the CIPP process. Conversely, the Sunbelt team could not situate all four pipes on the north side of the canal, as there wasn’t ample room to place the pipes and safely perform the fusion process. Working with the site’s restrictions, the Sunbelt team split the four discharge pipes, placing two to the south of the canal and two to the north.
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Although the two pipes to the south didn’t create much of an issue, the team had to design a temporary bridge that could safely and securely carry the weight of the two northern pipes across the canal. To accomplish this, four 12-in. x 50-ft steel I-beams were installed across the canal, laying MegaDeck mats on top. Then, 2-in. ratchet straps were then used to secure the mats to the I-beams and the pipes to the entire structure. After the system was erected, the two pipes on the north side of the canal traveled parallel to those on the south side until they reached the downstream stop where all four pipes conveyed into one 36-in. connection.
Conclusion
This project required careful attention to safety practices to ensure minimal disruption to the surrounding environment. During the construction phase of the bypass, the golf course remained open, requiring a keen focus on safety to diminish the potential for increased risk to our personnel and the general public. In addition, extra care was taken to ensure that the impacted waterway and its inhabitants would be protected from any dangers the temporary sewer system might expose.
Despite these additional considerations, the Sunbelt team finished the build a week ahead of schedule with zero recordable safety incidents. Since the project launched, it has been successfully running for three months with an anticipated completion goal of mid-October.
