From Waste to Glass
It's a fascinating story. But the legacy is deadly. For nearly 50 years, the Hanford Site in southeastern Washington produced plutonium for the creation of nuclear weapons. Today, its toxic legacy remains-53 million gallons of radioactive and chemical waste stored in 177 underground tanks. At least 1 million gallons of waste have already leaked, contaminating the groundwater, and threatening the Columbia River and millions of people downstream. Engineering, construction and project management company Bechtel National Inc. (Frederick, Md.) is helping to reclaim the environment by constructing the world's largest radioactive waste treatment plant. Its mission: to turn waste into glass. And surveyors have an essential role to fulfill in this process: they must assist in the construction of the plant at every stage of its progression.
The Manhattan ProjectIn 1939, physicist Albert Einstein warned President Franklin D. Roosevelt of the possibility that Nazi Germany was developing nuclear weapons. The American response to the growing threat of World War II's Axis powers was the Manhattan Project, a massive, highly secretive research endeavor to develop nuclear capabilities. Named after the Manhattan Engineer District of the U.S. Army Corps of Engineers based in New York City, where much of the early research was done, the Manhattan Project was carried out in three then undisclosed cities-Los Alamos, New Mexico; Oak Ridge, Tennessee; and Hanford, Washington. The Manhattan Project culminated in the design, production and detonation of three nuclear weapons in 1945. Plutonium from Hanford was used in one of the two atomic bombs that brought about the close of WWII in Asia. By its peak in 1945, the project employed more than 130,000 people and cost nearly $2 billion.
The Hanford SiteThe 500,000-acre Hanford Site was chosen for its remote location and abundant water and electricity available from the Columbia River and Grand Coulee Dam. In 1943, residents of three small towns-Hanford, White Bluffs and Richland-were relocated and the Hanford Engineer Works facility was built.
After WWII, Hanford continued to produce plutonium for the build-up of Cold War weapons; all told, Hanford produced more special nuclear material than any other place in the world. At its height in 1964, nine nuclear reactors or "piles" were operating on the banks of the Columbia, the powerful waterway flowing from Canada into the Pacific Ocean at the Oregon coast. These reactors were built during an era ungoverned by environmental regulations; eight of the nine piles directly contaminated the river, which is also the principal hatchery for Chinook salmon and steelhead trout. The waste contamination threatened the health and safety of people and wildlife in the area.
The majority of the radioactive and chemical waste was stored in 177 underground tanks built from the 1940s to the 1980s. Designed to last 20 years, the tanks held millions of gallons of waste; to date, according to the Department of Energy (DOE), 67 tanks have leaked an estimated 3.8 million liters of radioactive waste. When production was finally stopped with the fall of the Iron Curtain in 1989, Hanford faced a massive nuclear waste cleanup job.
The PlanIn December 2000, the DOE awarded Bechtel National Inc. a contract to design and build a plant to immobilize the radioactive waste. The solution: vitrification, a process that converts dangerous waste to stable glass to isolate it from the environment. The treatment project begins with a massive venture involving construction of a vast complex of waste treatment facilities, which is estimated to take 10 years, cost $5.7 billion and employ up to 3,000 people.
Vitrification pretreats and separates the waste between high- (primarily solids) and low-level (fluid) radioactivity. The waste products are separately blended with molten glass and poured into large stainless steel canisters where they are cooled, sealed and decontaminated. The high-level waste will be permanently buried deep underground at a federal geologic repository in Nevada. Low-level waste canisters will be buried in trenches well away from the Columbia River. The waste remains stable and isolated from the environment as its radioactivity dissipates over thousands of years.
But before this massive dissipation can begin, the treatment facility must be built.
The Construction ProjectCovering 65 acres and designed to operate for 40 years, the Waste Treatment Plant at the Hanford Site includes three major facilities-Pretreatment (PT), Low-Activity Waste (LAW) Treatment and High-Level Waste (HLW) Treatment-as well as the Balance of Facilities (BOF), which includes a large analytical lab, operations and maintenance buildings, utilities and office space. In October 2001, site preparation began; the first concrete for the nuclear facilities foundation was placed in July 2002.
For the project, DOE requires written procedures and "verbatim compliance" for all work done: what's written must get done. Literally thousands of procedures have been written for the project and everything is documented. The surveyors involved in the project, who include Bechtel employees as well as subcontractors, must adhere to the many heightened requirements for safety, accuracy, quality control and quality assurance due to the sensitive elements of the radioactive waste.
DOE has inspectors and observers onsite to watch over the entire construction process. The Defense Nuclear Facilities Safety Board oversees the DOE; other federal agencies, such as the Environmental Protection Agency, examine the work as well, adding additional pressure for high quality work.
The Hanford Engineering Works site covered 500 square miles, most of which remained unused. While some isolated areas are radioactive, many are not. The construction site is free of radioactive contamination, as are areas now being turned into wildlife refuges. And the area is constantly monitored.
Bechtel runs each of the four main construction areas-PT, LAW, HLW and BOF-as separate projects, with surveyors reporting to each area's lead field engineer. In addition, the plants are all set up as design/build projects with dynamic-moving timelines.
The design/build method was chosen because of the project's critical timeline. While all radioactive waste has been moved from the leaking single-walled into double-walled tanks, every effort is being made to forestall further leaks that could damage the surrounding area. Constant groundwater checks are made to ensure that no further leaks have occurred. Time is of the essence-and surveyors are doing their part to move forward quickly.
Because of this, design is not far ahead of construction in some cases, which produces challenges when design changes are made. Surveyors check daily for construction document updates because they have a mandate to work according to the latest revision. Since Bechtel uses Infoworks, a proprietary online database, that's not difficult-but it does essentially require an extra surveyor acting as a dedicated data manager for each area. These surveyors focus on managing the database, dealing with modified design files, preparing data, writing reports and creating CAD drawings.
The SurveyingBechtel surveyors and subcontractors work on the WTP project as an integrated team in all areas. The main surveying subcontractor is White Shield Inc. (WSI, Kennewick, Wash.). In addition, other subcontractors, such as the grading company, George A. Grant Inc. of Richland, Wash., provide surveying for their tasks. In 2001 there were seven Bechtel surveyors on the project; today there are 26 Bechtel and 24 subcontractor surveyors, as well as about 900 day and 90 night craftworkers. Because of the project's critical nature, surveyors remain onsite to serve and be a part of the construction team. This can be challenging when the vibrating rollers and man-operated compactors impact the sensitive surveying equipment. Sometimes surveyors have to wait until craftworkers take breaks or vice versa. Communication between workers is therefore vital to ensure efficiency and uninterrupted progress on the site.
Surveyors provide positioning wherever needed; Bechtel and WSI use Trimble (Sunnyvale, Calif.) GPS equipment. Bechtel also utilizes Trimble and Nikon optical total stations and Trimble Terramodel software. For GPS work, Bechtel uses a Trimble 5700 base station on the site with several Trimble 5700 rovers with Trimble TSCe controllers taking corrections off the base. At this site, Bechtel has six Trimble 5600 DR (reflectorless) total stations and two Nikon 851 total stations.
The initial control and topographic survey was done prior to Bechtel surveyors joining the project; subcontractor Rogers Surveying (Richland, Wash.) provided six control points. Local horizontal control is based on the Washington State Plane coordinate system. Vertical control is based on sea level; site elevation is about 680 feet above sea level. This is important since each of the three major buildings uses a different 0 elevation for design data.
Bechtel surveyors first verified control and expanded the network to about 50 control points. Today surveyors continue to maintain the network, replacing destroyed control where needed using Trimble 5609 DR total stations with high accuracy EDMs. The control surveys are analyzed and adjusted with StarNet software (Starplus Software, Oakland, Calif.). The vertical control network is surveyed using Trimble DiNi 12 digital levels with an Invar high-precision leveling rod; these same levels are also used for settlement monitoring of the major structures.
The project's nature requires the survey work to be done in segments. For example, one huge excavation-30-35 feet deep-was dug out for the lower portions of the LAW and HLW buildings. No underground utilities could be installed in the excavation area until the facilities' lower levels were completed and the hole backfilled, which took two years to complete. That meant a lot more stakes; surveyors often stake only 100 feet or less of an underground alignment since that is all that can be installed. The utilities seem to almost form an underground city: electrical duct banks, plastic pipes built into rebar and concrete; chemical pipes; electrical power and communication lines; five different water systems-fire, potable, chilled, cooling and storm sewer; and a compressed air system. Surveyors work in chunks and layers; since everything can't be staked simultaneously, surveyors have to make sure the stakes are placed correctly. Some stakes may go in now, with the remainder placed next year.
Surveyors also conduct as-built surveys of all utilities before they get backfilled. The project employs GPS for all utility staking. If something is grade-critical, a level or total station will be used to check elevations. With the Trimble 5700 GPS base station set up on the site, both Bechtel and WSI surveyors use Trimble 5700 GPS rovers for the utility staking.
Construction of the three main buildings started in the summer of 2002. The largest-PT-is larger than four football fields. The buildings are massive concrete and steel structures. The PT's basemat is 8 feet thick; many walls are 3 and 4 feet thick, with some up to 7 feet thick. As of mid-April, the structure of the smallest building-LAW-was about 75 percent complete; concrete is still being placed on the HLW and PT. All embedded objects, such as pipe sleeves, embed plates and electrical conduits, are surveyed to ensure they are located within design tolerances before the formwork is closed and concrete is placed. Each item has different location tolerances, ranging from 2 inches down to 3/16 of an inch. Surveyors also are sometimes required to recheck the embeds after the concrete is placed.
Total stations are used for this construction portion; in particular, Bechtel has benefited from the reflectorless, or direct reflex (DR) feature on the Trimble 5601 and 5609 DR total stations. Many of the targets are high above workers; the DR feature allows surveyors to climb to the target with a prism less frequently. It's made a big productivity difference.
All design work is done in MicroStation software (Bentley; Exton, Pa.); survey data managers read the design model daily, bringing the areas needed into Trimble Terra-model software to create working drawings. For the embeds, data managers get a center coordinate from the CAD model and compare that with a coordinate calculated from the latest approved construction drawings before preparing data files for downloading to survey instruments. If, as sometimes happens, there is a discrepancy between the model and the design drawing, design engineering is consulted for a resolution.
As the project continues, the surveyors' tasks will remain largely the same as described. For surveyors, it's been an exciting project to work on due to its sheer size and environmental importance: the survey team is helping to prevent what could be a huge environmental disaster. As the survey team watches what is essentially a small city being erected, it's gratifying to be part of such a critical and important effort.
*As this article is being written, another change is taking place: the project is being rescheduled to deal with technical challenges and funding constraints. The full effects of the change are uncertain, but it is likely that the work will take longer and cost more.