Recovery at Bad Creek
The Bad Creek Hydroelectric Project called for building a 1,065-megawatt power station inside a mountain, blasting tunnels and shafts, and impounding a lake by building two dams and a dike.
Duke lacked experience in tunneling and typically hires contractors for earthwork. So the company engaged two major contractors, one for the tunneling and another for the earthwork. Duke's own work force is building the powerhouse.
Work progressed on or ahead of schedule in 1985 and 1986. Then, in 1987, events forced the announcement of a year's delay in project completion.
By late 1989, Bad Creek had more than recovered the lost time. Carey York, the construction project manager, said, “It appears now that it is within our grasp to finish ahead of schedule.”
Current projections, though unofficial, show all four units on target for completion by the end of 1991.
SOLVING THE TECHNICAL PROBLEMS
The Scroll Cases
Because of manufacturing defects, several sections of Bad Creek's four scroll cases had to be recast. This delayed delivery of the scroll cases-a milestone critical to meeting the project schedule. But through some exceptional welding, the lost time was made up.
Looking a bit like giant snails, the scroll cases are joined by 20-foot lengths of pipe to the penstocks, which supply water to the turbines. Vanes inside the scroll cases direct water evenly against the turbine blades, improving the plant's operating efficiency. Each scroll case weighs about 200 tons and ranges from 8.5 feet to 34 inches in diameter.
Each scroll case arrived on site in four sections. The weld joint edges were prepared above ground but, because of their size, the scroll case sections had to be joined inside the powerhouse.
Made of high-strength steel, the scroll cases were susceptible to cracking. To prevent cracking, welders had to heat the joints before and after welding. They also had to bake their welding electrodes.
Duke welding specialist Bill Sams says, “The most difficult problem was the fitups. On this size joint, you would normally want no more than a quarter-inch gap, but we had places I could put my hand through. The welders had to do a lot of back-gouging, buildup work and grinding.”
Much of the welding was done inside the scroll cases. Grinding filled the air with particles. As the joints were preheated, temperatures inside the scroll cases rose to 120 degrees.
All the welds underwent nondestructive testing. Some required X-rays; the rest, magnetic-particle testing.
Welders completed the first-scroll case without a reject-able defect. Representatives of the scroll case supplier were skeptical. They re-examined the X-rays and reached the same conclusion: no defects.
Bad Creeks welders finished the remaining scroll cases over the next few months, using more than 10,000 pounds of weld filler material. Every weld was tested. None had a rejectable defect.
“To the best of our knowledge, this is the first time this has ever been done,” said Sams. “Four consecutive scroll cases welded with absolutely no repair.”
One supplier representative said that in his 25 years of experience around the nation, he had never seen even one scroll case welded without a defect.
By their near-perfect welding, Bad Creeks welders avoided several thousand hours in projected rework. This saved thousands of dollars and helped Duke Power gain on the project schedule.
The Powerhouse Crown
To contain the powerhouse, the tunneling contractor blasted a cavern 433 feet long, 164 feet deep and 75 feet wide out of solid rock. Creating this huge void released enormous stresses that had built up inside the mountain over millions of years.
Duke geologist Malcolm Schaffer said, “We found the horizontal stresses reasonably high and the vertical stresses 2 1/2 times what you would normally expect. You'd normally expect the vertical stresses to be about equal to the amount of rock on top.”
The completed spiral case for Unit #2 with the teat head attached. The spiral case quarter sections were welded together using 10,000 pounds of filler material without a repairable defect. The scroll case is then hydrostatically tested to 1368 psi, 150% of design pressure.
Schaffer and others expected some cracking in the crown, or ceiling, or the powerhouse. What was not expected was the extent of cracking.
Dan Rogers, head of Duke's design engineering team on site, put it this way “If you took a loaf of bread and started squeezing in the sides, you would see an arching of the top of the loaf. It was the same situation here, because you had more pressure on the sides of the cavern than on the top.”
Shotcrete, used to line the rock surface, began to peel off the crown, creating a hazard for those working below. To protect the workers, work in the powerhouse was stopped.
To repair the crown, the loose material was scaled off, more than 1,000 rock bolts installed, and a steel safety net installed underneath the crown. The rock bolts, ranging from 3 to 10 meters long, pinned up the large slabs of rock in the crown.
Construction engineer Julian Davis devised a special rig for installing the rock bolts. “We put a counter-weighted platform on top of the 25-ton bridge crane. We took a jumbo drill off its tractor and mounted it on this platform. The platform provided a 26 by 40-foot surface on which people could work.”
The bridge crane, which will be a permanent part of the plant, travels on rails that extend from one end of the powerhouse to the other. On top of the crane, the drill rig could reach all points in the crown, where holes were drilled and rock bolts inserted.
Largely because of Davis's ingenuity, the crown repairs were finished months ahead of the estimate.
At peak, more than 2,000 people worked at the Bad Creek Project. The company's work force numbered about 1,500; the tunneling contractor, about 150; and the earthwork contractor, about 600. Duke's work force included both regular company employees and contract labor.
In 1987, it was decided to expand the use of contract labor at Bad Creek. Many of these workers are highly skilled. Many are former Duke employees, but now they work through an agency, and they know their work is temporary.
To maintain good employee relations, little distinction is made between contract and company employees. Contract workers are mixed with Duke's regular work force. Some crews have all contract labor, some have all Duke labor, many have both.
A crew with all contract labor may report to either a company supervisor or a contract supervisor. A crew with all Duke employees or with both contract and Duke employees will report to a Duke supervisor. Duke employees do not report to contract supervisors, because of differences in policies and benefits.
To gain employee commitment to project goals, management placed heavy emphasis on communication. Billboards along the access road admonish employees to work safely. In the powerhouse, electronic bulletin boards flash messages on safety and the day's critical activities. Posters throughout the site inform employees of work status and schedules.
Because the work force is so dispersed, supervisors at Bad Creek are equipped with two-way radios. In the office, employees use such high-tech systems as phone mail and electronic mail. Print media, such as newsletters and pamphlets, are used extensively.
Frequent meetings are held at Bad Creek to keep everyone involved. Crews meet to discuss job safety, work status, company news and ideas for work improvement. People from the crafts and support groups meet to solve problems and plan future work. People from engineering, construction and other organizations meet to integrate schedules and address issues that cross departmental lines.
Duke has several departments represented on site, in addition to the Construction and Maintenance Department (CMD). Design engineers give speedy solutions to engineering problems, which otherwise would be referred to the corporate office in Charlotte, North Carolina, 150 miles away. People from the Purchasing Department solve procurement problems. People from the Operating Department identify potential operating problems as systems are installed and tested. Quality Assurance inspects work and tests materials, equipment and systems.
By late 1988, site managers from the different departments met to share their views, plan for the future, and reinforce their commitment to the project.
To encourage teamwork—and reward hard work—Bad Creek celebrates project successes. The occasion may be reaching a project milestone or passing a million hours without a lost-time injury. Management sponsors these celebrations. Funds collected from the site's vending machines help cover the cost.
Atypical celebration in CMD involves food. Bad Creek varies from that tradition only in method. Instead of hiring a caterer, Bad Creek's managers served barbecue to employees. One hot summer day, the project manager passed out ice cream cones. On another occasion, one manager passed out doughnuts. On yet another occasion, managers supplied free coffee all day.
Bad Creeks managers say the cost of these celebrations has been insignificant compared to the gains in morale. And high morale, they say, has been a major factor in Bad Creek's performance.
Keeping Safety First
From the top level, Duke's management over the years has put safety first-over schedule, over quality, over productivity. From the beginning, Bad Creek has kept safety as its top priority.
There was a business angle, of course. On-the-job accidents drive up insurance, worker's compensation and other costs associated with employee absences. But managers also put safety first simply because they don't like to see anyone get hurt.
Signs, posters and electronic bulletin boards urged Bad Creek employees to work safely. Supervisors met at least once a week with their crews to discuss ways to ensure safety in the work at hand. Both company and contractor employees were required to take part in several safety training programs, including underground rescue and hazard recognition.
A map of the Bad Creek area showing Lake Jocassee, the upper reservoir, and the transformer yard.
Bad Creek also put a few new twists on a safety program being used throughout the Construction and Maintenance Department. This program calls for a committee to inspect the site for safety violations and to offer instruction in job safety. Each crew appoints someone to work with the committee and point out unsafe conditions to the rest of the crew. This assignment rotates every three months.
But Bad Creek went further. A mannequin doused with red paint was left in various poses to simulate job accidents. Bloodied eyeballs and other body parts-artificial, thank goodness—were displayed to dramatize why employees should follow certain rules. Someone who called herself “Safety Susie” broadcast safety messages over the project's radio system. Skits such as a mock funeral, complete with pallbearers and casket, were staged on site.
Bad Creek's incidence rate for recordable injuries is much less than the U.S. average for construction, according to the Bureau of Labor Statistics. In 1989, the S.C. Chamber of Commerce gave Bad Creek a “certificate of excellence” for its overall safety achievements.
In early 1990, Bad Creek employees reached another safety milestone: 2 million consecutive work hours without a lost-workday case.
Steve Alexander, Human Resources manager at Bad Creek, says, “We have never compared ourselves to the construction industry. We have always remained part of the utility industry. Even on that basis, our frequency and accident rates are extremely low.”
Building in Quality
The Bad Creek Project has a strong commitment to quality. Fortunately, most company employees had worked at the company's nuclear stations, where work must meet extremely tight quality standards.
For nuclear projects, federal regulations require comprehensive quality assurance programs, with heavy emphasis on tests, inspection and documentation. Even though these rules did not apply to hydro stations, a similar QA program was used at Bad Creek.
Joe Shropshire, the project QA manager, says, “The quality of work at Bad Creek is just as good as it was in our nuclear program, but without all the paperwork. We have been able to focus on the job and work as a team to produce the required results.”
Nuclear regulations require separate organizations for quality assurance and construction. The idea is to free the QA organization from the pressures to meet construction schedules.
This separation has continued at Bad Creek. But with less emphasis on documenting results, inspectors are able to work more closely with craft workers. Together they correct mistakes while the work is being done, thus avoiding the expense of later rework.
Craft workers at Bad Creek are taught to “build in quality” rather than wait for inspectors to catch their mistakes. To make sure they understood the quality criteria that applied to their work, craft supervisors took part in the same training given to QA inspectors.
Ken Webber, Bad Creek's craft manager, says the training quickly paid off. He estimates that 90 percent of the project's nonconformances came from the crews of supervisors who had not yet received the QA training.
By 1989, rework accounted for less than 2 percent of all craft work hours. The average for the construction industry is about 5 percent.
Molding the Organization
Early in the project, Duke focused on gathering a skilled work force and starting work in the powerhouse. Ken Webber was named craft manager and placed in charge of the craft organization.
The east dike under construction. Nearly 14 million cubic yards of earth were moved to construct the two dams and this dike in creating the 27,148 acre-foot upper reservoir.
An aerial view of the construction yard showing the temporary offices, shops, warehouses, material storage yards and parking lots.
Reporting to Webber were several general supervisors. Several craft supervisors reported to each general supervisor.
Selection of the general supervisors was based largely on their technical expertise. In the early stages, for example, powerhouse construction would center on concrete placement. So a general supervisor who had heavy experience in concrete placement was put in charge of the civil work. By a similar selection process, other general supervisors were placed over the mechanical and electrical work.
Building a powerhouse underground presented special problems. As work progressed, space became cramped. There was no room to stockpile materials or bring in extra cranes. Work at one level had to be completed before work could begin the next level up. Managers compared underground construction to building a ship in a bottle.
Work under these conditions required a high degree of. coordination. It wasn't enough to know the priorities in civil, mechanical or electrical work. Priorities had to be based on where work was taking place inside the powerhouse.
So the powerhouse was split into areas, and each general supervisor was placed in charge of a certain area. The support groups adjusted, too, so that each general supervisor had support people dedicated to the work in his area. The general supervisor was then held accountable for all the work in his area.
With the project nearing completion, the focus has shifted again, this time toward completing and testing the plant's mechanical and electrical systems. So again the craft organization was altered. Two general supervisors were switched from area to system responsibilities. One has taken charge of mechanical systems; the other, electrical systems. Another manager has been added to oversee building the turbine/generators,
Vast amounts of reinforcing steel, concrete and other materials went into the Bad Creek powerhouse. Steel pipe nearly 14 feet in diameter lines the penstocks. Four spherical valves, each weighing 170 tons, have been installed to control water flow into the powerhouse. Each of the station's four generator rotors weighs a hefty 430 tons.
Because of the rough terrain, the site offered few areas suited for warehouses and material storage yards. The site Duke chose is about 2.5 miles from the powerhouse. Trucks bound for the powerhouse travel down the access road, with its sharp curves and steep grade. Then they head down the access tunnel about a quarter of a mile to the powerhouse.
A Cline tractor backs a section of penstock liner down the 1,100 foot main access tunnel into the powerhouse. The penstock section is 66 feet long, 13.5 feet in diameter and weighs about 104 tons.
The powerhouse is totally underground. It offers two points of access-the access tunnel and vertical shaft. There is little room to unload and store materials and few places to install cranes and other construction equipment.
As powerhouse construction began, trucks brought materials down the access tunnel to one end of the powerhouse. There materials were unloaded and moved by mobile cranes to the powerhouse floor, about 100 feet below.
Crews competed for access to the few cranes in the powerhouse. The time spent waiting for cranes reduced their productivity.
Duke took several steps to increase the number of hooks. Construction engineer Davis says, “The scheme was to have one big crane that does the big pieces and make sure the little cranes can get out of the way when there is a big piece to be picked up.”
Duke engineers looked at installing two permanent 250-ton bridge cranes in the powerhouse. But, says Davis, “The cost of one 500-ton crane and one 25-ton crane was a lot less than two 250-ton cranes, plus the hooks could work better. The little 25-ton crane did not require much space and could run back and forth much faster.”
The 25-ton crane, which uses the same rails as the 500-ton crane, was installed first. A jumbo drill was mounted on the 25-ton crane to repair the powerhouse crown.
While still mounted on the 25-ton crane, the jumbo drill was used to suspend a temporary 10-ton crane from the crown. This temporary crane can lift small loads over the permanent cranes and has significantly reduced the time spent waiting for cranes.
Small tower cranes that could be disassembled and reassembled in a few hours were used. These cranes took up a relatively small space and could be moved quickly. This allowed more cranes to be placed in the powerhouse, and where they were needed most.
“Ninety percent of the loads in the powerhouse are less than 10 tons,” says Davis. “We covered every area in the powerhouse with a small hook.”
Initially, the only place to unload trucks was at one end of the powerhouse, The bridge cranes picked up loads there and moved them to wherever they were needed in the powerhouse. This bottleneck slowed material delivery.
Duke's design engineers planned to add a drainage passage around the powerhouse. The construction people needed to increase access to the powerhouse. So they collaborated to design a bypass tunnel that cuts across the other tunnels.
The bypass tunnel ends about midway down the powerhouse, At this point a temporary 24 by 30-foot platform was built that protruded over the powerhouse floor. Braced by cantilevered steel beams, this dock could support two fully loaded concrete trucks. It dramatically improved the ability to move materials into the powerhouse.
Building the powerhouse would take more than 150,000 cubic yards of concrete. That volume justified the building of two concrete batch plants on site in the transformer yard.
The transformer yard is on the surface about 450 feet directly above the powerhouse. To get from the yard to the powerhouse, trucks must go about two miles down the access road, then down the main access tunnel.
To avoid clogging the access road and tunnel with a steady parade of mixer trucks, two 12-inch shafts were drilled from the batch plants to the access tunnel, near the powerhouse. Workers in the batch plants mixed the concrete and dropped it down the shafts. Waiting below, near the powerhouse cavern, were mixer trucks. The trucks caught the concrete, remixed it and fed it into the pumps that carried the concrete to the point of placement,
Material Delivery System
Materials personnel process 275 orders on an average day at Bad Creek. In 1989, Bad Creek's material handlers made more than 10,000 deliveries, representing more than 52,000 line items. That same year, a lack of materials accounted for less than 1 percent of all problems reported by Bad Creek's craft supervisors.
In the mid-1980s, an industrial engineering study was conducted that led to the development of Bad Creek's material delivery system. This system called for doing as much work above ground as possible and for delivering materials “just in time,” The idea was to avoid congestion in the powerhouse, mater i a l losses and large inventories.
Bad Creek's material delivery system was linked to the project's planning system and the corporate Material Inventory Control System (MICS). The link to the planning system allowed Bad Creek to integrate delivery schedules with project work schedules. The link to MICS helped site personnel make sure the materials were on site when needed.
The material delivery system required a high degree of coordination between organizational units. A material coordinator was assigned to each general supervisor. This coordinator's job was to work with engineers, planners, purchasing agents, warehouse personnel, suppliers and others to make sure the crafts had the right materials when needed.
“We tried to be very customer oriented,” says Bob Lynn, Bad Creeks materials and equipment manager, “Whatever our customer needed, we tried to get it—not from a standpoint of controlling material, but just making it available.”
Here's how Bad Creek's material delivery system works:
1. A planner reviews the design drawings, prepares a bill of materials, anti enters this information into MICS. The planner also enters schedule and accounting information.
2. MICS makes sure enough material is available. If not, MICS sends a report to Bad Creek's inventory control group, which reorders the rnaterial. If the material is available, MICS assigns it to the particular work order.
3. The material coordinators work with up to 30 craft supervisors to determine exactly what quantity of material is needed each day.
4. The material coordinators order the materials from Bad Creek's customer service group. The order specifies the material, when it is needed and where it should be delivered including to which craft supervisor.
5. Using MICS, customer service personnel prepare in order ticket and enter the information on a PC-based tracking system,
6. Storage personnel receive the order, prepare the material for issue, and inform the material delivery group.
7. Material delivery personnel check the material. Then they inform the material coordinator and crane coordinator that the material is ready for delivery.
8. The material coordinators recheck the material when it arrives in the work area and then notifies the craft supervisor.
“The material coordinators,” says Lynn, “feel as accountable as craft people do.”
PLANNING AND SCHEDULING
Two principles guide project management at Bad Creek:
- Plan the work in detail and
- Keep the crafts focused on croft work.
Even though detailed planning takes time and money, Bad Creek's managers say that this investment pays off in reduced rework, less idle time and increased productivity.
Bad Creek managers wanted the crafts focus on direct work, They wanted welders to weld, pipefitters to fit pipe, millwrights to set equipment and other craft workers to do what they were hired to do.
So management acted to remove the support burden from the crafts. The support groups took full responsibility for providing materials and equipment and for planning and scheduling the crafts’ work.
Project Control System
Duke implemented its Project Control System (PCS) at Bad Creek in 1986 to plan the construction work in detail. PCS calls for planning all craft work, with the level of detail based on the complexity of the work, It calls for involvement by both craft and support personnel, to gain the commitment of everyone involved in the work. PCS entails measuring performance, with emphasis on improving methods and rewarding superior performance.
The chief product of PCS is a detailed work package, which the construction organization calls a “commitment package,” or “compak.” Based on a work breakdown structure, the compak includes:
- a description of the work (its scope);
- a work schedule (listing activities and cost codes);
- a description of the resources needed;
- bills of material, sorted by activity;
- an environmental compliance checklist;
- safety and security checklists;
- a list of special tools and equipment needed for each activity;
- a description of inspection requirements;
- a description of performance requirements (the schedule and work hours allotted);
- notes, assumptions and special instructions; and
- the names and phone numbers of the people who developed the compak.
Design Engineering releases its drawings for Bad Creek at least six months before craft personnel start work on a particular activity. Site personnel develop the compak at least three months before the work starts, These deadlines allow time for material procurement, shop Fabrication and schedule changes.
About four weeks before the work starts, the responsible planner, scheduler and craft supervisor meet at the place the work is to be done. They review the compak to make sure the plan still reflects conditions at the work site. They also review the assumptions and the work planned for adjacent areas. They then negotiate any changes to the plan and the craft supervisor commits to it.
AS the work is being done, the craft supervisor jots down any problems with the plan. When the work is clone, the supervisor meets again with the planner and scheduler to discuss lessons learned. These lessons become part of the historical basis for future plans,
Three levels of schedules control work at the Bad Creek Project.
The project schedule contains about 60 major milestones. Progress toward meeting these milestones is reported to the overall manager and corporate management,
Bad Creek's Division Master Plan (DMP) identifies about 6,000 work activities, each lasting two to three months, It integrates the schedules of the departments involved in construction, testing and start-up. It identifies design release dates, material delivery dates, resources needed and the project's critical path.
The DMP is maintained on Primavera, a PC software program. It provides weekly reports and is the project's chief management tool.
A detailed work schedule is a comprehensive plan used by a craft supervisor to manage a crew. This schedule includes activities lasting five days or less. It describes day-by-day work sequences for the crew. It also identifies related work other crews must do.
Most of Bad Creek's schedulers are assigned to support certain craft supervisors working in specific areas. They integrate work plans, acquire resources and report weekly status. At the start of each week, they identify what work each supervisor must complete to remain on schedule. Information collected by the schedulers is compiled each week and used by management to assess progress. If needed, detailed schedules for the coming weeks are adjusted to meet the overall project schedule.