In April, the Mears Group, Inc. completed a design-build project in Jacksonville, FL to allow a regional energy producer to expand its natural gas pipeline to serve new facilities.
To complete the project, Mears drilled a 7,400-foot pilot hole at a depth of 130 feet beneath the St. John’s River bottom to install a 16-inch steel pipe.
Though just 1.4 miles of the 50-mile pipeline that ends at the Jacksonville Electric Authority’s (JEA) Greenland Energy Center, the section under the St. John’s River proved the most daunting during the planning stage. “To go from one side of the river to the other proved to be the biggest obstacle,” said Mark Haney, director of engineering for TECO Peoples Gas, the company that owns the pipeline.
Haney said HDD was virtually the only option to install the pipeline through that area. “Other than HDD, there were no good options.”
But project officials said the timing of the project was also a major issue.
Haney said that the pipeline providing service to the power plant needed to be operational by Jan. 1, 2011. That means JEA was dependent on the pipeline being in place in time to move forward on the operation of the power plant. To help ensure a timely project, TECO hired Mears to complete a design-build project.
“If it is not built on time you literally have a billion dollar power plant with no fuel,” said John Fluharty, project manager for J.R. Giese Operations, Mears’ sub-consultant that handled engineering duties for the project.
Fluharty says design-build allowed Mears to drill a pilot hole months in advance to pulling the product pipe into the bore to ensure the project was feasible.
“TECO wanted to know early enough in the process that the project was feasible in the event they needed to go in another direction,” Fluharty said. “TECO wanted a true partnership put together so they could work out all the issues related to this special feasibility hole we drilled in advance.”
Design-build is relatively new to the HDD industry, according to Fluharty.
Design-build offers a subtle but important difference from the typical procedure for HDD projects. In the typical process, a company such as TECO would hire an engineer to develop plans, procure a construction company to implement those plans and then construct the project — often called design-bid-build. Design-bid-build requires multiple contracts.
With design-build, however, a single company is hired to engineer and build the project, all under a single contract.
Susan Hines of the Design-Build Institute of America says utilizing design-bid-build can create contention between the engineer or designer of a project and the company that constructs the project. She said it creates a disconnect between the two parties which can often turn contentious because of concerns of liability and litigation. For instance, Hines said when the construction company finds changes need to be made to the design during the construction, it takes paper work and dialogue for the changes to be approved and implemented.
“This often slows things down,” Hinds said.
In the end, design-build projects help to improve two important aspects of any project: money and time.
Design-build projects cost at least 6% less than design-bid-build projects and are constructed 12% faster, according to the Design-Build Institute of America. At the same time, the institute reports that design-build projects earned a higher owner satisfaction than other project concepts.
“One of the main advantages of design build is the fact that everyone on the design and construction job is on the same side,” Hines said. “They are all sharing in the risks and the rewards of a job well done.”
She added: “Owners save money and they save time.”
Mears drilled the feasibility pilot hole for the project in November 2009. Product pipe was pulled in April 2010.
Mike Maxwell, Mears’ project superintendent, said the crew drilled from both sides of the St. John’s River and intersected the two holes under the river bed — a waterway lined with stately homes and used mostly for recreational purposes.
A 330,000-pound rig was used for the pilot hole on one side of the river and a 140,000-pound rig was used to drill from the opposite side.
Mears utilized its 500,000-pound rig to perform the reaming and to pull the product pipe through the hole, Maxwell explained. “The crews reamed the bore to 24-inch diameter and then swabbed the hole before pulling in the product pipe. The crew drilled through sandy silt before making it to clay for the drill’s running depth.”
“It was fairly easy going; we were able to use a jetting bit all the way through,” he said.
Maxwell said the length of the drill, combined with the unique aspects of the job, made it a satisfying accomplishment.