REHAB WINNER: Sewer Rehabbed Using Design-Build & Sliplining

For one California sewer district, its inaugural use of design-build on a trenchless project led to a savings of more than $3 million in costs and one year from an expedited timeframe to get the project done and operational.

The project itself proved to have its own challenges, requiring its contractor Kiewit Infrastructure West to tap into its experience to complete the project, which involved sliplining 2,600 ft of a 78-in. pipe and 23,810 ft of a 48-in. pipeline along Magnolia Street in Orange County. Along the way, the contractor also rehabbed a double-barrel siphon into a self-cleaning siphon and relined 30 manholes.

The Magnolia Trunk Sewer Rehabilitation Project is the 2012 Trenchless Technology Project of the Year for Rehabilitation.

The Orange County Sanitation District (OCSD) is responsible for collecting, treating and disposing the wastewater generated by 2.5 million people living in a 21-city, 479-sq mile area of central and northern Orange County. OCSD consists of two operating plants, referred to as Plant No. 1 located in Fountain Valley, and Plant No. 2 located in Huntington Beach. Within the district’s scope are 580 miles of sewer and is, by population, the sixth largest sanitation agency in the United States. OCSD is familiar in the use of trenchless methods and have used them on past projects.

The Magnolia Trunk Rehabilitation Project required close coordination with the cities of Fountain Valley and Westminster and was adjacent to the cities of Garden Grove and Huntington Beach, just six miles south of Disneyland. The pipeline crossed under a major freeway, as well as main thoroughfares in two cities that produce high volume traffic at all times. To minimize potential impacts to the local residents and businesses, use of trenchless technology was needed.

The PVC-lined sewer pipe was constructed during the 1950s and had deteriorated over the years through joint failures and corrosion. OCSD had tried to address the problems using spot repairs but was determined to come up with a long-term, structural repair as this was a major service line (flow from this pipeline ran from 19 MGD to 13 MGD) for its customers.

OCSD knew it wanted to use trenchless technology to solve the situation but it also wanted to keep costs down and its options open as to which trenchless method offered the best value; OCSD also knew design-build would offer this to them. District officials determined this was the perfect project to use design-build vs. design-build-bid to meet its needs.

Design-build is a method to deliver a project in which the design and construction services are contracted by a single entity known as the design-builder or design-build contractor. In contrast to design-bid-build, design-build relies on a single point of responsibility contract and is used to minimize risks for the project owner and to reduce the delivery schedule by overlapping the design phase and construction phase of a project.

For OCSD to proceed, it needed a change in the California public contracts code that would permit the agency to pursue design-build, which prior to the change only permitted OCSD to utilize design-build-bid. The code change came in 2009, giving OCSD the opportunity to utilize this construction methodology.

“The Magnolia Trunk project was well suited for design-build as it would allow for different alternatives for rehabilitation to be considered,” says OCSD assistant general manager and director of engineering Jim Herberg. “This would allow us to compare the different trenchless options without delaying the construction process.”

Because of the size of OCSD’s overall capital improvement program, it contracted for project management with IPMC Inc. (a joint venture between Parsons and CH2M Hill) to augment OCSD’s staff. Alberto Acevedo served as the project manager through the joint venture for the Magnolia Trunk Rehabilitation Project, and is vocal proponent of design-build.

“This is a great way to do a project. It helps to shorten the time of delivery because the design runs parallel with construction,” Acevedo says. “In this case, the cost of design fees was reduced significantly, totaling approximately $800,000.”

OCSD contracted with AECOM to develop the design-build procurement documents for the project, which allowed for the different trenchless options to be proposed. Among the proposals OCSD received were four using sliplining and one proposing cured-in-place pipe (CIPP), the latter which would have required an above-ground bypass pumping system. OCSD evaluated the design-build proposals and determined that Kiewit Infrastructure West Co.’s RFP for sliplining offered the best value in terms of price, timeframe and service.

“Typically, the owner puts out a RFP and engineers respond with a proposal for design services, the owner selects three to five proposals for final evaluation and selection of a contractor is made and negotiates a notice to proceed. The NTP  can take three to six months, followed by a preliminary design report, which can take another three months,” says senior project engineer Paul Wilson, with Malcolm Pirnie, water division of ARCADIS,  “The preliminary design is followed by a 30 percent design and review, then a 60 percent, and so on. The design phase can take a year to 18 months to get a project into construction. Design-build shortened the delivery process by nine months.”

The choice of sliplining for the structural rehab of this sewer pipeline was a no-brainer, says Brandon Sjulin of Kiewit Infrastructure West, as it offered the best price, schedule and was least disruptive option to rehab this pipe. With this pipeline, sewer flow could not be disrupted and had to be maintained throughout the project, which is not an issue with sliplining so constructing a bypass pump system was not necessary. Sliplining also minimized traffic interruption to the neighborhood’s residents and businesses, including schools, he says.

“Based on the street traffic volumes and the location of where the bypass pumping that would be required to perform CIPP, the live-flow sliplining without any bypass was a big public relations element selected by the design-build team,” says Sjulin.

Construction began four months after Kiewit’s proposal was accepted and required a committed team effort by all involved once it started, as this was the first design-build project ever done by OCSD. “All team members, including the OCSD, its engineers at AECOM and Kiewit and Malcolm Pirnie, committed to upfront weekly taskforce meetings and permit workshops so we had no surprises or delays during the project,” Sjulin says.

The project scope was to structurally reline 4.5 miles of 48-in. pipe and a half mile of 78-in. corroded reinforced concrete pipe. This was accomplished with 13 access pits where placement of HOBAS low-profile bell joined CCFRPM pipe with 40-mil non-reinforced vinyl ester liner was inserted with the sizes ranging from 36 to 48 in. in diameter; runs as long as 3,200 ft were accomplished. One unique element of the project was a 36-in. twin barrel siphon, which was to be made into a self-cleaning siphon that would minimize debris settlement; this was accomplished by pulling in 21-in. HDPE through each barrel.

In addition to traditional excavation sliplining, Kiewit chose to use an Akkerman Hydraulic Pushing Machine to push the new pipe into the existing line, with the annular space filled with grout afterward. A Vacuworx RC-10 was used to lift and load the pipe into place prior to sliplining.

Another challenge that the contractor and OCSD faced was the generation of odors during construction due to elevated hydrogen sulfide gas levels from a separate wastewater treatment plant project. To mitigate the release of the potential nuisance odors, Kiewit used carbon scrubbers and an upstream dosing of chemicals using Bio Organic Catalyst from Green World Technologies, which prevented release of the odor.

Substantial completion was accomplished within 13 months from notice to proceed, which included design, permit procurement in a heavily regulated environment and construction of 13 slipline reaches and the rehabilitation of the siphon system. OCSD was more than pleased with its first effort of a design-build project.

“This was a complicated project of a major trunk line,” says Herberg. “Because this was our first design-build project, we had no standardized templates or documents to start with and we had to train our staff about design-build. Using design-build, this project was completed faster and was less costly. We are looking at other design-build candidates for future projects.”

Sharon M. Bueno is managing editor for Trenchless Technology.

Project Owner: Orange County Sanitation District
Engineer: Malcolm Pirnie, Water Division of ARCADIS
Contractor: Kiewit Infrastructure West
Manufacturers: Akkerman, Vacuworx, HOBAS Pipe
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