Table I Wastes and Other Materials Generated During the Cooling
Towers Demolition Project and Their Disposition
E. P. Larson and A. C. Lay
Lockheed Martin Energy
Systems, Inc.
T. L. Hatmaker
Oak Ridge National Laboratory
R. DiDonato
Foster Wheeler Environmental Corp.
R. L. Yust
Science Applications International Corp.
ABSTRACT
The Cooling Towers Demolition Project consisted of the demolition and disposition of 6 out-of-service cooling towers, removal and disposal of radioactively contaminated sediment from the cooling tower basins, and demolition of 28 other auxiliary services facilities. This project was located at the Oak Ridge K-25 Site, a government-owned, contractor-operated facility managed by Lockheed Martin Energy Systems, Inc., for the U. S. Department of Energy (DOE) in Oak Ridge, Tennessee. These structures were associated with the deactivated gaseous diffusion process for uranium enrichment. The basins varied in dimensions but averaged approximately 8 m deep, 18 m wide, and 107 m long, creating four reservoirs of approximately 18million liters each, which were essentially full during operations. During operations, the cooling towers provided approximately 1.4 (breve) 106 L/m (204 (breve) 106 L/d) of process cooling water.
The project was conducted using a partnering agreement between three prime contractors, where the partners shared liabilities for fines and penalties and shared in profits and loses. The scope was broken into the following three distinct phases:
- cooling tower superstructure demolition,
- removal of sediment from the cooling tower basins, and
- demolition of above-grade basins and auxiliary facilities.
The first demolition phase of the project was preceded by the de-energizing of site facilities and construction of approximately 2 miles of security fencing to isolate the area from the rest of the K-25 Site. The superstructure demolition phase included the demolition of the wooden superstructures; removal of the fan assemblies and shrouds; removal of the fire protection sprinkler system; and removal of asbestos-containing materials (i.e., transite siding and Munters fill). The sediment removal phase consisted of the removal, dewatering, transportation, and disposal of over 2,600 m3 of radiologically contaminated sediment from the basins. The third and final phase was the demolition of above-grade concrete cooling tower basins and 28 auxiliary facilities. The auxiliary facilities consisted of fire sprinkler valve houses, clarifiers, liquid storage tanks, and pumphouses.
Each phase of demolition was preceded by site characterization and integrated waste management planning. Chemical and radiological analyses of the superstructure wood and sediments were conducted. The final phase of the demolition required the characterization of the auxiliary facilities for lead (in paint), asbestos, mercury, and polychlorinated biphenyls. The basins and auxiliary facilities were also characterized for radiological contamination by following a project-developed radiological release protocol that was pre-approved by DOE and the State of Tennessee. The major waste streams identified were wood, asbestos, sediment, and concrete. Metal generated by the demolition of theses facilities was commercially recycled.
INTRODUCTION
Construction of the Oak Ridge Gaseous Diffusion Plant (now known the Oak Ridge K-25 Site) began in 1943 as part of the Manhattan Project effort during World War II to supply enriched uranium for nuclear weapons production. Located 10 miles west of Oak Ridge, Tennessee, the K-25 Site is one of three sites on the U.S. Department of Energy's (DOE's) Oak Ridge Reservation. The world's first diffusion facility for large-scale separation of uranium-235, the K-25 Site was placed on standby in 1985 when demand for enriched uranium declined and was shut down in 1987.
During operations at the K-25 Site, the process buildings required cooling towers to transfer heat from recirculating process cooling water into the atmosphere. Support systems--such as make-up water, water softening and clarification, pH control, surge protection, electrical power, fire protection, pumping capability, and corrosion prevention--were housed in nearby auxiliary facilities. Basins for the cooling towers varied in dimensions but averaged approximately 8 m deep, 18 m wide, and 107 m long, creating four reservoirs of approximately 18million liters each, which were essentially full during operations. The cooling towers provided approximately 1.4 (breve) 106 L/m (204 (breve) 106 L/d) of process cooling water for process operations.
The Oak Ridge K-25 Site Cooling Towers Demolition Project provided a safe, cost-effective, and efficient method for the demolition and disposition of the cooling tower facilities in the K-25 Site Decontamination and Decommissioning Program. The specific elements of the project included:
The project was divided into three phases:
Responding to DOE's desire for contract reform, Lockheed Martin Energy Systems, Inc., Foster Wheeler Environmental Corporation, and MK-Ferguson of Oak Ridge established a teaming arrangement to perform work for DOE using project task orders contracts, thereby accepting increased corporate risk and the challenge to reduce costs using cost-plus incentive fee contracts.
Efficiencies were achieved through eliminating redundant oversight activities; simplifying project reporting; collocating project teams; and maintaining close coordination among parties, including DOE and the Tennessee Department of Environment and Conservation. Increased corporate risk was evidenced by acceptance of liability for fines and penalties, third-party lawsuits, and shared project cost overruns. In addition, failure to achieve project health and safety goals would result in decreased fees.
DESIGN ACTIVITIES
Procurement Package
Phased funding by DOE dictated that each phase of the project be dealt with separately. Performance specifications that allowed contractors to be innovative were prepared for each phase of the project. The end results and project criteria, rather than methods of accomplishment, were specified.
The project team issued clear and concise, integrated, project-specific procurement packages, bound as one document. On other projects, government procurement packages are usually prepared by a minimum of three independent parties, and all site-specific requirements--project related or not--are typically issued with the bid packages. This often produces conflicts and redundancies within the package and results in contractors increasing their bid amounts. The Cooling Towers Demolition Project procurement packages were prepared by the project team. In addition to the technical requirements, the procurement package contained only references to federal and state regulations, applicable DOE order requirements, and applicable site procedural requirements. A summary of the characterization results and materials disposition table from the Waste Management Plan were also incorporated into the procurement package.
The procurement package used graphically enhanced photographs extensively to describe such items as 1) work activities to be performed by the contractor, 2) work activities to be performed by others, 3) construction/demolition interface points, 4) components requiring protection from damage, and 5)hazardous materials to be removed prior to demolition. As-built drawings of the facilities did not exist, so rather than generating a costly sketch (involving field trips, measurements, and CAD designer and equipment time), photographs were enhanced. These photographs were also used as a tool during the prebid meetings. Feedback from contractors indicated this method was well liked and was an effective means of communication. This method also allowed contractors to readily recall their site visit.
Contractors were requested, via a Commerce Business Daily announcement, to submit a qualification package. These packages were reviewed by the integrated project team, and the technically qualified contractors were invited to attend the prebid meeting.
Site Preparation
A boundary fence was constructed to segregate the project site from the K-25 Site protected area, and access to the site was controlled for the duration of the project. This restricted access was necessary for many reasons: mainly accountability, safety and health, and the use of uncleared workers.
The project team de-energized the utilities prior to mobilization by the contractor. This activity included removal of a section of pipe/conduit at points demarcating the interface of the contractor's responsibility. This provided visual verification that each circuit or system was de-energized and not operative during removal activities, thereby ensuring safe removal.
Water in the basins, which had accumulated over a period of time, was pumped out after passing through a 5µ filter. The project team continued to perform this activity until the sediment removal contractor was mobilized.
PHASE 1--SUPERSTRUCTURE DEMOLITION
The objective of the superstructure demolition phase was the removal and disposition of the wooden superstructures and the materials directly associated with them. The superstructures were constructed out of both chromated-copper-arsenic (CCA)treated wood and nontreated wood. Postconstruction treatment of the wood involved spray applications of chemical compounds to mitigate and delay fungal attack.
Characterization & Regulatory Determination
The primary purpose of the superstructure characterization was to determine whether the wood and miscellaneous metal could be free-released. A statistical survey was conducted that included both surface surveys of the towers and bulk analysis of the wood. The survey was designed statistically to provide 95% confidence levels. The surface analysis of the superstructure was conducted by performing external and contamination (i.e., probe and smear) radiation surveys. The bulk samples of the wood and Munters fill (a heat transfer material in blocks 30 cm square by 1.8 m long) were analyzed for Toxicity Characteristic Leaching Procedure (TCLP) organics, TCLP metals, uranium, technetium, total activity, and dioxin/furan.
The results of the superstructure characterization indicated that the surface measurements of the wood were below the guidelines in DOE Order 5400.5 (DOE 1990) of 1000 dpm/100 cm2, removable, and 5000 dpm/100 cm2, total contamination, for alpha and beta/gamma, respectively.
The results of the bulk analysis indicated that the cooling tower wood was not a listed hazardous waste under the Resource Conservation and Recover Act (RCRA) and met the characteristic exemption criteria for treated wood and therefore was not a RCRA hazardous waste. Trace quantities of dioxins and furans were present in the wood due to degradation of pentachlorophenols, but it was found that the isomers of dioxins and furans present in the wood had a low toxicity. The radiological analyses were evaluated statistically and found that potassium-40 and uranium (<35 pCi/g) were present in the wood.
Demolition Activities
Prior to demolishing the wooden superstructures, hazardous materials and external hardware had to be removed, which included oils in the gearboxes, asbestos-containing materials, electrical conduits and wires, fan shrouds, fan blades, gearboxes, return cooling water standpipes, and fire protection piping. In addition, a woven fabric netting was secured over the basins to catch any wood that might fall during demolition. This was intended to prevent wood from coming into contact with the radioactively contaminated sediment.
Three asbestos-containing materials in the towers needed to be removed prior to superstructure demolition. The three materials were Munters fill, transite siding, and a felt fire wall material between the cells. The removal was performed under negative pressure by enclosing the towers in plastic and using large negative-air machines. All asbestos was handled per federal and state regulations. Approximately 1900 m3 of asbestos-containing materials were removed and disposed at the on-reservation landfill.
The wooden superstructures were demolished using either a clamshell/crane or a grappler/track-hoe. Both devices provided maximum safety for personnel performing the work, as minimal personnel access on the cooling towers was required. Dismantlement operations were conducted remotely by a crane operator and his flagman. Pieces of the towers were broken off, lowered to the ground, segregated, reduced in size, and loaded into trucks for transportation to an on-reservation landfill. The remaining piping was segregated from the wood after it was on the ground. All metal associated with the superstructure was considered potentially contaminated and was taken to the on-reservation scrap yard for future recycle. Approximately 4200 m3 of wood and 750 m3 of fiberglass were disposed at the on-reservation landfill.
PHASE 2--SEDIMENT REMOVAL
The objective of this phase was to remove all radiologically contaminated sediment and water from the facilities and dewater the sediment to decrease the volume, thereby reducing packaging, transportation, and disposal costs.
Over 2600 m3 of sediment (composed primarily of dirt, dust, silt, pollen, rust, and scale) was contained in the basins. During warm weather, algae and fungi covered a portion of the surface of some basins. In addition, large amounts of superstructure wood had fallen into the basins during the superstructure demolition phase.
Characterization & Regulatory Determination
The purpose of characterizing the sediment in the cooling tower basins was to make regulatory determinations for appropriate handling, labeling, and waste management and to identify potential hazards to workers involved in the removal and demolition. Seventy-three sediment samples were collected and analyzed for TCLP organics, TCLP metals, dioxins/furans, gamma spectrometry, technetium-99, strontium-90, isotopic uranium, plutonium, thorium, neptunium-237, total uranium, and total activity. The sampling strategy was developed around accessibility issues related to the superstructures, and a sampling plan was developed for the one basin that allowed good access. (The other basins had accessibility issues that limited sampling to only the outer edges of the basins.) The objective was to gather samples that gave a credible representation of the sediment in the basins. An extensive chemical review of the processes used during operations, prior to the cooling towers shutdown in 1985, indicated that the sediment would not currently have TCLP components in soluble form and would not fail TCLP analysis. This process knowledge, supported by analysis, indicated that the sediment was not RCRA hazardous waste. The radionuclide analysis indicated that the sediment was a low-level waste.
Methods Used to Remove and Dewater Sediment
The specifications required that representative samples of the dewatered sediment pass the paint filter test ("Test Method for Evaluating Solid Wastes," EPA SW846-9095) and have a moisture content that would allow handling without the creation of airborne hazards.
During the course of the project, different material-handling and dewatering techniques were undertaken. Initially, a filter press was used to dewater the sediment; however, fragments of wood caused problems during filter press operations. Wood fragments also caused blockages in the pump, which caused the sediment to set up in the process line. Agitators were used to keep the sediment fluid once it reached the feed tank to the filter press; however, pumping and suspension continued to be a problem during the course of work. After processing approximately one-third of the sediment, it was determined that the sediment could pass the paint filter test if allowed to drain and dry while still in the basins; filter press operations were therefore discontinued. The sediment was drummed within the facilities with the aid of skid steer loaders and manual labor. Large pieces of wood and other debris were segregated by hand. Other methods of transferring the sediment were also attempted to optimize removal and dewatering efficiency. Conveyors, settling tanks, vacuum trucks, and mixers were all used with varying degrees ofsuccess.
Packaging and Shipping
The contractor was required to ensure that all drums of sediment were absent of free liquids, but a random sampling of 88 drums prior to the initial shipment showed that 41% (36 drums) had free-standing water. A corrective action was required to meet the disposal criteria at the disposal site and was instituted on all drums. The free-standing water was removed using a vacuum system and an absorbent spread over the top of the sediment prior to closing the drums. Upon completion, a total of 10,890 drums and 116ST-5 boxes of sediment were transported to a disposal site in Utah in 166 over-the-road shipments. The drums were loaded in a configuration ensuring that the maximum axle weight and gross vehicle weight limits were not exceeded.
PHASE 3--BASINS AND AUXILIARY FACILITIES DEMOLITION
The objective of the basins and auxiliary demolition phase of the project was to demolish and dispose the cooling tower basins by removing the above-ground basin walls and 28 other associated facilities.
Characterization & Regulatory Determination
To facilitate the objective of maximizing the commercial recycle or disposal of materials from the demolition process, a protocol for radiological release of facilities for recycle/disposal was developed, as required by DOE Order 5820.2A (DOE 1988). The release limits were compliant with DOE Order5400.5 (DOE 1990) and the Nuclear Regulatory Commission Regulatory Guide 1.86 (NRC 1974). The protocol was reviewed and concurred with by both the DOE and State of Tennessee.
This radiological survey was performed to identify the presence and extent of contamination on accessible surfaces. The survey was conducted in accordance with the approved protocol, including compliance with NUREG/CR 5849 (NRC 1992). Each area within the facilities was categorized as either potentially affected or unaffected by radiological contamination based on historical information and past survey data. The number of statistical sampling points was chosen based on whether a facility was categorized as affected or unaffected. Three types of surveys were used to identify the contaminated areas. A biased survey in each building consisted of a scan of all accessible areas considered most likely to be radiologically contaminated. In addition, a survey of all accessible floor areas and a statistical survey of the facilities were also taken to identify contamination. The surveys were conducted in order to be compliant with the release limits of 1000 dpm/100 cm2, for transferrable contamination, 5000dpm/100 cm2, average total, and 15,000 dpm/100 cm2, maximum total contamination. Approximately 280 m2 of concrete surfaces were found to be above these limits and were decontaminated.
The basin/auxiliary facility characterization included the collection of data for asbestos; lead, cadmium, and chromium in paint; mercury; polychlorinated biphenyls; metals analysis for residues in chemical storage tanks; and roof samples for radiological analysis (gamma spectrometry, technetium-99, and isotopic uranium).
Beneficial Use and Recycle
The project team met with the State of Tennessee to discuss using the basins as unpermitted, planned fill areas to contain demolition rubble composed of concrete and block from the demolition process. It was agreed that the material could contain up to 1% incidental materials, as no demolition activity can ensure that all materials can be removed. The fill was contoured to ensure appropriate drainage, covered with crusher run or soil from the reservation's borrow area, and vegetated.
By meeting the requirements of the radiological release protocol and free-releasing the facilities, approximately 770,000 kg of metal were recycled. The recyclable materials [primarily structural steel, rebar, and some miscellaneous equipment (e.g., pumps, piping, switchgear, and conduit)] were sold to a local scrap metal broker. In addition, using approximately 5600 m3 of demolition rubble as fill avoided the cost associated with disposal and backfill.
Method of Demolition
Demolition of the basins and auxiliary facilities was accomplished with conventional heavy equipment. The smaller concrete facilities (i.e., sprinkler valve houses) were demolished with a hydraulic hoe-ram. Initially, the concrete clarifiers were demolished using the hydraulic ram; however, it was soon determined that the specification requirement of 30 cm top size for earthenfill could not be met without additional processing. A concrete crusher jaw was then used to demolish the clarifiers and above-grade basin walls. Metal components were size reduced using torches.
Final Site Configuration
The final site configuration consisted of various slabs on grade, exposed slabs, gravel areas, planned fill areas with crusher run cover or grass cover, open basins with perimeter fall protection, numerous exposed concrete pedestals, and utility poles. All below-grade valve vaults; utilities (e.g., sanitary sewer, fire protection); and process systems (i.e., recirculating cooling water) were left in place. Building utilities were disconnected and capped, plugged, or flanged at grade. Overhead electrical and/or communication lines were disconnected and terminated at the nearest utility pole. The project boundary fence, which was erected prior to initiation of the project, remains in place to support the reindustrialization effort at the K-25 Site; all vehicular and pedestrian access gates, however, are open. There are no additional requirements for surveillance and maintenance on the Cooling Towers Demolition Project.
SUMMARY
Cost and Schedule Performance
The project team's proposal to DOE was negotiated at approximately $23M for the entire project, which included project planning, characterization, design, decontamination, health and safety oversight, environmental oversight, and demolition. The estimated cost at completion was approximately $19M, resulting in a total savings to DOE of approximately $4M. Overall, the project was completed 3 months ahead of schedule.
Procurement Performance
The integrated procurement package resulted in the average bids being within 1% of the government estimate. The three awarded bids were, on average, 28% lower than the government estimate.
Safety Performance
Over 200,000 man hours were worked with only one recordable injury.
Environmental Compliance
No Notices of Violation or Notices of Deficiency were issued from regulatory agencies.
Waste Management
The project successfully accomplished the waste management objectives. All waste materials were properly disposed; recyclable materials were recovered, where cost effective; and the contractor maintained responsibility for its own wastes.
Table I shows the major wastes and materials generated during the course of the project as well as the disposition of these materials.
Table I Wastes and Other Materials Generated During the Cooling
Towers Demolition Project and Their Disposition
CONCLUSIONS
The K-25 Site Cooling Tower Demolition Project successfully demonstrated that innovative methods and commercially recognized approaches could be applied to DOE work. In particular, the following conclusions can be made:
Integrated project teams are critical to the success of the project. The "team" in this project consisted of DOE, state regulators, DOE prime contractors and subcontractors, and the demolition contractor.
BIBLIOGRAPHY
DOE (U.S. Department of Energy) 1988. Order 5820.2A, "Radioactive Waste Management."
DOE 1990. Order 5400.5, "Radiation Protection of the Public and the Environment."
NRC (Nuclear Regulatory Commission) 1974. Nuclear Regulatory Commission Regulatory Guide 1.86, Rev. 0, "Termination of Operating Licenses for Nuclear Reactors."
NRC 1992. NUREG/CR 5849, "Nuclear Regulations Manual for Conducting Radiological Surveys in Support of License Termination."
* The submitted manuscript has been authorized by a contractor of the U.S. Government under contract DE-AC05-840R21400. Accordingly, the U.S. Government retains a paid-up, nonexclusive, irrevocable, worldwide license to publish or reproduce the published form of this contribution, prepare derivative works, distribute copies to the public, and perform publicity and display publicly, or allow others to do so, for the U.S. Government purposes.
The Oak Ridge K-25 site is managed by Lockheed Martin Energy Systems, Inc., for the U.S. Department of Energy under contract DE-AC05-84OR21400.