TODAY'S BUSINESS ENVIRONMENT CONTINUALLY PRESENTS CHALLENGES of a fundamentally conflicting nature. Electric utilities face increasing energy demand and a smaller internal workforce to meet those demands. Systems must be either upgraded or expanded during a period with strong cost-containment requirements.
For some major new projects, many utilities are electing to use a less traditional construction approach: engineer-procure-construct (EPC). This can improve the project schedule and speed of delivery, shift risk from owner to contractor and avoid increasing the utility's workforce.
EPC, or design-build relationships, are nothing new; however, they have traditionally been more common in power plant and other commercial-industrial construction. Today, many contractors are finding a niche in the EPC arena on larger T&D projects. The contractor teams with an engineer and a material manager, and operates directly with the owner as a single-service provider. Cost savings and quality improvements can be achieved if one service provider manages the design, construction and materials procurement, and downstream maintenance.
MidAmerican Energy Co. (MEC; Des Moines, Iowa, U.S.) serves more than 650,000 customers in a 10,600-sq-mile (27,454-sq-km) area in Illinois, Iowa and South Dakota, U.S. In 2004, MEC awarded The L.E. Myers Co., a subsidiary of MYR Group Inc. (Rolling Meadows, Illinois), a large EPC transmission contract to move electric energy from new coal-fired generation at the Council Bluffs Energy Center in southwest Iowa to the grid supplying power to the central part of Iowa.
For this 124-mile (200-km) transmission project stretching halfway across Iowa, Myers teamed with engineering partner Stanley Consultants (Muscatine, Iowa) and materials management partner Hamby Young (Aurora, Ohio, U.S.). This EPC team has a considerable track record in transmission and substation work, as well as experience working together.
The L.E. Myers Co. has constructed thousands of miles of transmission line, distribution line and associated substations for voltage up to 765 kV.
Hamby Young has been packaging substation, transmission and distribution projects up to 765 kV for more than 30 years.
In the past two years, Stanley Consultants has designed more than 304 miles (489 km) of transmission line up to 345 kV, and 146 new and upgraded substations up to 500 kV. Prior to the award of the MEC Project, Stanley Consultants worked with MYR Group subsidiaries for more than 25 years on various projects in the more traditional engineer-bid-construct method.
MYR Group subsidiaries include The L.E. Myers Co., Sturgeon Electric, Harlan Electric, Hawkeye Construction and Great Southwestern Construction. The possibility of teaming with MYR Group for design-build assignments was broached four years ago, and since that time, Stanley Consultants and MYR Group have completed design-build projects in Phoenix, Arizona, U.S., and Denver, Colorado, U.S. Hamby Young has also worked with Stanley Consultants and MYR Group on previous projects.
The EPC approach on the MidAmerican Energy project involves the constructor early in the design phase, so that a continuous constructability review is part of the design process. This also provides for flexibility in the field; when problems are encountered, the constructor and the engineer are already practiced at working together to resolve issues. The project schedule benefits from an EPC approach in that construction can be concurrent with design, and procurement can follow a logical process that allows for long-lead-time equipment to be ordered early on in the project. MEC is provided with a single-source “responsible party.” Compliance with client standards is also improved because the entire team understands those requirements at the start of the project.
The Council Bluffs to Grimes Transmission Project consists of a new 345-kV/161-kV Grimes Substation and 108 miles (174 km) of 345-kV/161-kV double-circuit line from the Council Bluffs Energy Center to the Booneville Substation and 16 miles (26 km) of 345-kV/345-kV double-circuit line from the Booneville Substation to the Grimes Substation. The Grimes Substation is located north of Iowa's capital city, Des Moines, at the edge of the city's expanding development.
The new line will use existing corridors to avoid additional impacts to landowners. Therefore, the line has to be designed for a double-circuit arrangement to accommodate the new 345-kV line to Council Bluffs Energy Center and the existing lines that presently occupy the right of way. To avoid power interruptions to the Iowa towns of Earlham, Atlantic and Avoca, outages have to be managed carefully and coordinated with the Midwest ISO.
The transmission line will be a vertical double-circuit configuration using davit arms on weathering steel-pole structures, which weigh up to 176,400 lbs (80,014 kgs). Thomas & Betts (Memphis, Tennessee, U.S.) is drop-shipping structures out of its Hager City, Wisconsin, plant directly to work sites due to the scarcity and cost of developing adequate lay-down yards in the area. There are 736 self-supporting steel structures on the project, with pole heights ranging from 95 ft to 180 ft (29 m to 55 m) above the foundation. The foundations are up to 58 ft (18 m) deep and 13.5 ft (4.1 m) in diameter, and some may require as much as 310 cubic yards (237 cubic m) of concrete. The concrete design uses 10-ft (3-m) anchor bolt cages with full-length rebar. MidAmerican requires a dead-end containment structure every 5 miles (8 km) for cascade containment.
In order to maintain service and meet the schedule, Tri-State Drilling (Minneapolis, Minnesota, U.S.) is using low-drill excavators to place foundations under an energized 161-kV line. They normally place three to four tangent foundations each day, or approximately 16 per week. Because of the size of the foundations, casings are often used.
The steel poles are delivered directly to the right of way from the manufacturer using all-wheel drive tractors and rubber-tracked Challengers during wet conditions. The two-piece poles are framed and jacked together on the ground, and placed using a 125-ton (113-metric ton) all-terrain crane. The three-piece angles and dead-end structures are stacked, framed and jacked together in the air, and require a much larger crane for safety. All davit arms are fitted with dampers to avoid vibration damage prior to conductor stringing.
The conductor is T2 Dove, 556.5 ACSR with 24/7 stranding. The 345-kV section of the project is a two-wire, vertically configured bundle, and the 161 kV is a single conductor per phase. T2 is a motion-resistant conductor that will provide reliable service to MidAmerican during critical wind and ice periods. McLean Power System's lightweight polymer insulators with associated hardware in a V-string configuration supports the conductor.
Two different operations, one for the 161 kV and one for the 345 kV, are used for the conductor stringing. The 161-kV stringing uses the existing conductor as a lead line. The new conductor is then pulled in by connecting the new conductor to the old and using V-groove pullers. The 345 kV requires a hard line to be placed in the travelers and then the conductor is pulled into place using a three-drum puller. Several locations along the route require that the 345-kV portion be placed with the existing circuit energized, so clearances must be maintained and induction managed. T2 conductor is a more challenging conductor to install. Adherence to the manufacturer's specifications is important. This includes traveler bottom-of-groove radius, sheave diameter, tensioner groove size, and the use of eveners on the dead-ends and between the hard line and the conductor.
The project's extensive outage restrictions necessitate a very detailed plan for the line construction. And, as needed, the MidAmerican system operations team and MISO coordinate any changes and make any required updates to the plan.
The 45-acre substation site also offers challenges. MidAmerican purchased the substation site, originally a heavily tiled farm field, because of its proximity to existing transmission facilities. Design of the substation required removing and relocating existing field tile, raising the pad for the substation above the field and turning the entire area around the substation into a wetland. This wetland will not only support flora and fauna, but it will also retain runoff from the substation in heavy rainfall and reduce sedimentation into adjoining properties.
The new Grimes Substation will consist of five 345-kV line terminals, one 345-kV/161-kV transformer and two 161-kV line terminals, and will be a ring bus configuration. There are six 345-kV breakers and two 161-kV breakers, along with 15-kV reactors. Valmont Industries (Omaha, Nebraska, U.S.) is providing the line terminals, ABB (Zurich, Switzerland) is providing the SF6 breakers, Pauwels in Canada manufactured the autotransformer, Pacific Air Switch Corp. (PASCOR; Forest Grove, Oregon, U.S.) is providing all of the switches in the station, and Trench is providing the reactors.
The autotransformer bank, being shipped by rail from Canada to Minneapolis and then trucked to the site in Des Moines, is a 345/161/13.8-kV, 1050-650-150-kV BIL, 336-448-560 MVA at 65°C (149°F) unit. The breakers on the project are rated at 3000 A continuous current and 50,000 A interrupting capability.
POTENTIAL EPC BENEFITS TO THE OWNER
A traditional in-house design and bid process for a large special project causes the owner to assume a big portion of the risk associated with the design and procurement of material. The size of this project necessitates a larger-than-normal in-house project team. This places a heavy burden on many of the internal support organizations — such as human resources, stores and procurement, safety, engineering and quality-control personnel — normally out of the construction group.
An EPC project can be structured to shift as much risk as the owner would like onto the EPC contractor. This may cost a little more in the initial contract, but risk costs then become more predictable and manageable. The risks associated with design problems and the matching up of material to accommodate the design is shifted to the EPC contractor, along with a warranty period that is often longer than the normal warranties given. In turn, the owner is relieved of providing internal resources for this coordination issue.
More than 1000 activities are identified on the overall MidAmerican project schedule, tying together the engineering, procurement and construction for the project. This project is being performed on a fast track; engineering is continuing on certain sections while construction is already underway on other sections. The EPC process saves time compared to the traditional method by allowing construction to begin before the design is complete, and also because of efficiencies gained through constructability reviews with constructor and engineer during the design process.
The owner can expect high safety performance on an EPC project when a prime contractor has a strong safety program and is able to more effectively control the overall performance on the project. As prime contractor on the MidAmerican project, The L.E. Myers Co. requires a high degree of compliance from direct employees and subcontractors. All team employees must complete a safety orientation before being allowed on the project site. Myers also worked with the Iowa Occupational Safety and Health Administration at the beginning of this project to help develop a site-specific safety plan and identify unique challenges.
EPC projects can be a good alternative to increasing staff during short periods of high volume or “peak work.” This approach has been used in system power-generation expansion for years. An abundance of talent can be gathered for the project without the long-term obligation and cost of providing in-house benefits or severance packages at the end. This expansion of the workforce doesn't just apply to the design, procurement and construction groups, but it flows over into all support areas struggling to meet the fast-paced requirements of the project.
Completion of the Council Bluff to Grimes Transmission project is scheduled for August 2006 with the primary intent to move electric energy from the new generating facility to the power grid. The team of The L.E. Myers Co., Stanley Consultants and Hamby Young will have completed a successful EPC project, while MidAmerican Energy will have the necessary capital improvements to its system to provide safe and reliable energy to its customers without the burden of dismantling an internal project team that may no longer be needed.
If the projected amount of new transmission construction and upgrades over the next 5 to 10 years becomes a reality nationwide, the EPC approach may become a more common practice.
Gary Klocke is construction manager for the Grimes Project. He has 36 years of experience with The L.E. Myers Co., starting as a lineman and holding various management positions. Klocke has managed numerous 345-kV line construction projects throughout the years. email@example.com