Project of the Year 2017 Rehabilitation Winner: West Palm Beach Force Main Rehabilitation
West Palm Beach, Florida, provided the perfect setting to demonstrate just how important trenchless methods are to a community looking to upgrade its underground infrastructure with minimal disturbance and impact to its residents.
West Palm Beach officials turned to fiber-reinforced cured-in-place pipe (CIPP) to rehabilitate its 5,700-ft, 48-in. prestressed concrete cylinder pipe (PCCP) — its only artery to the facility that treats the raw sewage. West Palm Beach area is home to high-end properties and condos (upward of $10 to $20 million homes), a private country club with a Jack Nicklaus-designed golf course, as well as the longtime getaway for President Donald Trump.
This six-month project demonstrates how CIPP reduced the impact on operations for the municipality and golf course, while also maximizing flow capacity of the pipeline with minimal diameter loss. The project also necessitated the testing and reformulating of products to successfully withstand the pressure rating of the 48-in. diameter line.
And it also set a record.
“This is the first rehabilitation project to use fiber-reinforced CIPP at this pressure, diameter and length,” says Andrew Costa, area manager of business development at Insituform Technologies, which installed the liner.
This was also the largest pressure force main CIPP project that Jacobs Engineering has ever done.
This project also required meticulous planning with regard to jobsite access, equipment footprint and impeccable restoration to the properties involved, specifically the golf course’s fairways and putting greens.
“I was extremely proud of this project,” says Steve Lindsey, senior pipe rehabilitation specialist at Jacobs Engineering. “Everyone involved worked very diligently together and cooperatively. I wish they could all go this way.”
For all of these challenges, West Palm Beach Force Main Rehabilitation is our 2017 Trenchless Technology Project of the Year for Rehabilitation.
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Project Background
The East Central Regional Water Reclamation Facility handles 100 percent of the raw wastewater flow for the City of West Palm Beach and the Town of Palm Beach, treating up to 70 million gallons of sewage per day for approximately 100,000 residents. A single 48-in. PCCP that was built in the 1970s is the conduit to that treatment facility. Though there were no obvious issues with the pressure main, West Palm Beach officials wanted to have a thorough condition assessment of the main. Pure Technologies was brought in with its Pipe Diver system to perform the condition assessment.
Pure Technologies’ assessment concluded that enough pipe segments had broken wire wraps, with five to 100 broken wires per 20-ft segment — increasing the risk of future failure. Given how critical this line is to the City, officials chose a proactive solution: trenchlessly rehabilitate the line using fiber-reinforced cured-in-place pipe (CIPP).
For a project of this size, open-cut or sliplining are normally used; however, open-cut is too costly and disruptive and sliplining would have resulted in too great of a diameter reduction for the flow capacity of the line.
So, starting in spring 2016, work began on what would become one of the largest rehabilitation projects of its kind, considered Phase I (Phase II of the project is currently under way and involves nearly 6,000 ft of pressure main). The team at Jacobs Engineering was tasked with designing this important project, which involved several challenges, including the fact that the 48-in. pressure main could not be shut down at any point during the work. An immense temporary bypass system would need to be set up to keep flow going while crews relined the pressure main.
Sunbelt Rentals designed and constructed the bypass, which sounds simple enough but, in reality, was a massive undertaking by all involved. The end result was an elaborate bypass of four 24-in. HDPE lines strung out over 24,000 lf and over some highly sensitive properties — which in actuality was the most visible aspect of the project to the impacted residents. For a great deal of the project time, the bypass lines and insertions pits abutted private property along the project route.
The temporary bypass proved to be a critical piece of the project, as disturbance to the residents and club members and golfers had to be kept to a minimum and flow had to be kept active.
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“How do you string more than 24,000 feet of temporary 24-inch HDPE piping and valves across a golf course, crosswalks, canals, underneath a moderate-to-heavily traveled roadway, and across a high voltage transmission property? Very carefully, and with a significant amount of teamwork from the prime contractor, Insituform,” says Sunbelt Rentals national strategic account manager Ladd Gould.
Gould explains the bypass this way: Essentially, Sunbelt’s scope was to design and install a complex aboveground 30 MGD bypass to allow for uninterrupted service of the existing force main while Insituform installed the CIPP. This was accomplished by utilizing the existing pumps in the multiple pump stations feeding the 48-in. PCCP pipe, which allowed for a temporary pipe-only system to convey the flow around the rehabbed pipe segment.”
The force main was hot tapped by Rangeline Tapping Services without taking the primary line out of service. Once the valves were attached, Sunbelt Pump & Power Services set up the four 24-in. HDPE lines, each running about 5,700 ft. Three lines would have been sufficient but the fourth was added for redundancy and safety.
The project site is home to high-end properties and condos and a private country club with a Jack Nicklaus-designed golf course.
Structural Solution
With a MAOP of 25 psi and surge pressure of 35 psi, the pressure main required a structural solution. Together with Jacobs Engineering and West Palm Beach, the project was designed with materials to withstand the pressure rating of the 48-in. diameter line. Jacobs Engineering determined that an epoxy resin was the best choice to stand up to the structural and pressure requirements.
The project was divided into six separate lining shots — using liner that was 18 mm thick — with the largest length being 1,160 ft. “That is a pretty long length for fiber-reinforced pressure pipe,” says Costa. “These were all trucked-in shots and not an over-the-hole project.”
The CIPP liner was impregnated with epoxy resin in Indianapolis and then shipped to Florida for installation. The first tube shipment presented a challenge for the installation crew. A premature exotherm occurred during shipment and the liner had to be shipped back to Indiana for proper disposal and to determine the cause. Work resumed and installation was able to occur at a rate of shot per week, using water inversion and hot water cure.
The entire lining portion of the project took seven weeks.
Pressure Tests
A critical aspect of the project involved the pressure testing of the line once installation was completed. The pressure main was reconnected back to the rest of the system and pressure testing commenced to verify it could withstand the normal 25 psi operating pressure and 35 psi surge pressure. Each individual segment was pressure tested to withstand 55 psi. Afterward, the entire 5,700-ft length was pressure tested. All seven tests were successful and the line was put back in service in October 2016.
“With the diameter and the volume of water and the pressure, there was more than 100,000 lbs of force at the end cap,” Costa says. “We had to set up concrete thrust blocks and additional bracing pits to overcome that amount of force. There was so much force [during the testing] that it started moving the shoring in our pit.”
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Even before the project started, this aspect of the project went through considerable design and testing. “This type of lining system has historically been used for sewer lines under low pressure conditions,” Jacobs Engineering senior project manager Ray Thompson says, adding in recent years it’s been used for higher pressure conditions. Given that, product testing precipitated improvements to the fiber-reinforced CIPP system used, including the use of long-oriented chop fiberglass fabric and thermoplastic polyurethane coating. Testing of these new products in the lab and in the field showed better expansion capabilities and adhesion, longer shot lengths, increased diameter ranges, improved liner flexibility, reduced layer construction, decreased resin usage, higher pipe burst strength, greater composite strength and improved long-term corrosion resistance.
“It’s because of all of that that this project was able to be pressure tested at 55 psi, which at this diameter equates to more than 100,000 lbs of force,” Thompson says.
Final Thoughts
Projects of the scope and jobsites of this sensitivity and size require much more than just a community liaison to keep everyone on the same page and answer residents’ questions — and there were many of them during the six months of work, including handling their concerns when Hurricane Matthew blew through. Per the bid, Insituform hired a private public relations firm to handle the Public Outreach Program. Veronica Cooper with Cooper Construction & Management was responsible for this ancillary part of the project, which involved keeping the high-end residents happy and informed throughout the project.
“We had strong success through a team approach for mitigating community impact, preparing and responding a potential hurricane threat and focused on timely completion,” Thompson says.
Sharon M. Bueno is managing editor of Trenchless Technology.
