Rocky Flats Environmental Technology Site

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The Rocky Flats Environmental Technology Site is located approximately 26 kilometers (16 miles) northwest of downtown Denver in Jefferson County. The site is near a large metropolitan area that is currently experiencing rapid growth and development. Approximately 2.1 million people live within an 80-kilometer (50-mile) radius of the site. Current growth trends in the area are projected at 30 percent within the next 20 years.

The site is located at an elevation of approximately 1,800 meters (6,000 feet) on a geological bench called Rocky Flats. This bench flanks the eastern edge of the foothills of the Rocky Mountains, slopes down gradually to the east, and overlooks the Denver metropolitan area. The primary facilities are located on 155 hectares (384 acres) within the Industrial Area of the site. This core area is in the center of the site and contains more than 400 manufacturing, chemical processing, laboratory, and support facilities, which were formerly used to produce nuclear weapons components. Approximately 2,320 hectares (5,800 acres) of the 2,486-hectare (6,216 acre) site are preserved as open space. This open space contains few facilities and serves as a buffer zone for the core area.

FACILITY MISSION

Rocky Flats was built in 1951. From 1952 to 1989, the site's primary mission was to produce nuclear weapons components. The final products included components and assemblies manufactured from uranium, plutonium, beryllium, stainless steel, and other metals. Production activities included metalworking, fabrication and component assembly, plutonium recovery and purification, and associated quality control functions. Research and development in the fields of chemistry, physics, metallurgy, materials technology, nuclear safety, and mechanical engineering were conducted to accomplish this mission.

In 1989, many of the site's nuclear production functions were suspended after a safety review temporarily shut down plutonium operations. Following an extensive review, which included considerable independent oversight, Building 559, an analytical laboratory, was allowed to resume limited plutonium operations. Building 707, a plutonium foundry and machine shop, also successfully underwent the same type of independent oversight and obtained authorization from the Secretary of Energy to resume limited plutonium operations to stabilize plutonium oxide and repackage plutonium for safe storage. Production activities at the site resulted in the contamination of facility and environmental media with chemical and radioactive substances.

Rocky Flats was placed on the Superfund National Priorities List in 1989. In 1991, the Department of Energy entered into a cleanup agreement with the two principal regulatory agencies overseeing cleanup activities: the Environmental Protection Agency and the Colorado Department of Public Health and the Environment (formerly called the Colorado Department of Health). This Federal Facility Agreement and Consent Order, known as the Interagency Agreement, provides a legally enforceable framework for assessing the nature and extent of contamination; determining the risks posed by that contamination to workers, the public, and the environment; and implementing actions designed to remediate the contamination.

The Interagency Agreement is currently under renegotiation and is expected to be replaced by a new cleanup agreement in the near future. Successful renegotiation is expected to resolve some, but not all, of the regulatory issues identified for the site. Selected renegotiation of compliance with a number of Department of Energy Orders also is under way. Other areas of uncertainty also exist. The implications of the Defense Nuclear Facilities Safety Board Recommendations and the Price Anderson Act Amendments are still under review.

In January 1992, the termination of nuclear production changed the primary mission of the site from nuclear weapons production to cleanup and restoration. Landlord responsibility for the site was transferred from the Department of Energy Office of Defense Programs to the Environmental Management program in FY 1994.

The greatest liability at Rocky Flats is the potential health and safety risks posed by the presence of large amounts of Special Nuclear Material in its various forms. Special Nuclear Material consists of plutonium metal and oxides, as well as enriched uranium metal and oxides. Rocky Flats has 12.9 metric tons (14.2 tons) of plutonium (nearly 15,000 items) and 6.7 Metric Tons (7.4 tons) of highly enriched uranium in nuclear weapons parts, materials, process residues, and wastes. Much of this material has been stored in temporary packaging since 1989, when production operations involving radioactive materials were suspended. Approximately 30,000 liters (7,800 gallons) of plutonium solutions and 2,700 liters (700 gallons) of highly enriched uranium acid solution are stored in tanks that were not designed for long-term storage. Also, numerous former production process buildings contain gloveboxes, instruments, machine tools, walls, floors, tanks, pipes, and ducts contaminated with radioactive and hazardous materials.

The site's waste inventory includes approximately 3,200 kilograms (7,100 pounds) of plutonium in residues, 600 cubic meters (800 cubic yards) each of transuranic mixed and transuranic waste, 18,000 cubic meters (24,000 cubic yards) of low-level mixed waste, 5,500 cubic meters (7,200 cubic yards) of low-level waste, and 230 cubic meters (300 cubic yards) of hazardous waste.

From an environmental restoration standpoint, 177 Individual Hazardous Substance sites have been identified, prioritized, and grouped into 16 operable units according to location and type of contamination. Individual Hazardous Substance sites with potentially higher health and environmental risks are being addressed first.

There are more than 400 structures at Rocky Flats. Of these structures, 19 contain the majority of the Special Nuclear Material, classified products, radioactive and hazardous inventories, and radioactive and chemical contamination. The remainder of the facilities are uncontaminated or marginally contaminated support facilities. Some of these facilities are currently being evaluated for conversion to nondefense use.

FUTURE USE

The Rocky Flats future land-use decision process requires input from the public, environmental scientists, risk managers, land-use planners, regulatory specialists, and social scientists. To assist future site use decisionmaking, a working group was established to determine stakeholder and regulatory agency preferred future-use options. The Future Site Use Working Group consists of representatives from private and public constituencies: city and county governments, environmental and activist groups, landowners, economic development interests, neighborhood associations, federal and state regulatory agencies, and the Department of Energy. The group was charged with developing long-term, future-use options for the Rocky Flats site. The recommendations developed by the group were communicated to the Secretary of Energy on June 22, 1995.

The working group's recommendations were divided into three phases based on cleanup activities and the existence of radioactive material and waste onsite: (1) Phase I B inventory plutonium and wastes and consolidate onsite; (2) Phase II B remove consolidated plutonium and waste from the site; and (3) Phase III B complete initial cleanup. The Buffer Zone would remain primarily as preserved and managed open space with Controlled Access and protected critical natural areas. The Industrial Area would be cleaned up to levels enabling the conduct of environmental technology activities. No formal decision has been made regarding the site's final end state; however, the future use assumed for this report is illustrated in the Future Use map.

This baseline estimate closely follows the Future Site Use Working Group's recommendations, with the exception of the proposed Corrective Action Management Unit and a Resource Conservation and Recovery Act Subtitle C disposal cell. The future-use assumptions in this report have not been approved by Department of Energy Headquarters, the State of Colorado, or other affected stakeholders. These assumptions do not represent a decision regarding waste disposal, but result from a parallel planning activity currently in progress at Rocky Flats called the Accelerated Site Action Project or ASAP.

However, the details of the 1996 Accelerated Site Action Project plans were not available in time for incorporation into the 1996 Baseline Environmental Management Report. The Accelerated Site Action Project is a breakthrough planning approach for the site. It seeks to accomplish accelerated risk reduction and cleanup of the site decades before the path forward presented by the 1996 Baseline Environmental Management Report and for billions of dollars less in total costs. The Accelerated Site Action Project was developed as a phased effort to increase the efficiency of the nuclear material and facility stabilization and environmental cleanup activities, which are viewed as slow, uncertain in outcome, and costly. The basic premise of the Accelerated Site Action Project planning approach was to identify the interim and end states for the site and then to move aggressively toward these states. Early conclusions of the Accelerated Site Action Project planning effort were that the site should focus on plutonium stabilization and consolidation, deactivation of nuclear facilities (to recoup the high facility baseline costs) and then focus on decommissioning and environmental cleanup. Areas investigated in depth during the Accelerated Site Action Project are Special Nuclear Material, Waste Management, Facility Decommissioning, Environmental Restoration, Infrastructure, Cost and Schedule, Implementation and Risk. The Accelerated Site Action Project process has led to several interesting possibilities such as accelerated deactivation of high operating cost facilities to reduce operating costs quickly, and preferential stabilization of plutonium to reduce risk. The Accelerated Site Action Project will form the basis of the next Baseline Environmental Management Report for Rocky Flats.

NUCLEAR MATERIAL AND FACILITY STABILIZATION

Facility stabilization, maintenance, and monitoring involves the ongoing management of facilities until their ultimate disposition is achieved. Site facilities include buildings for chemical and metallurgical processing operations, as well as buildings contaminated with radiological and hazardous materials. The major nuclear material and facility stabilization activities for the site include consolidating and storing Special Nuclear Material, facility operations, surveillance and maintenance, and residue stabilization and facility deactivation. Stabilization activities are necessary to place residue materials in a stable configuration for safe storage and management and to begin the process of deactivating facilities.

Consolidation will result in a single Special Nuclear Material storage facility. Currently, Special Nuclear Material is stored within eight buildings in the Protected Area. The Special Nuclear Material is in various physical and chemical forms in a variety of packaging and containers. Because plutonium production operations were initially shut down temporarily, the solid Special Nuclear Material inventory remains primarily in temporary packaging, which will eventually show signs of degradation. As the packaging continues to age, the potential for release of package contents increases. Therefore, it is necessary to stabilize and upgrade the packaging and storage configuration. Repackaging the plutonium items into newly designed containers will improve material stability and allows for the collection and stabilization of plutonium oxides for long-term storage. Thermal stabilization (controlled heating) activities will eliminate the inherent ability for unstable oxides to ignite spontaneously. Repackaging for long-term storage is expected to be complete in FY 2002.

The largest contributor to the annual cost of facility operations has been the safe operation and maintenance of 19 buildings in which radioactive and other hazardous materials are stored or handled. These buildings were originally used for manufacturing processes and were designed to allow safe work on fissile materials or other radioactive materials. These facilities were operated, monitored, and maintained to ensure public, environmental, and worker safety. Several buildings have been in service for almost 40 years and are approaching or have exceeded their design life. Older buildings have higher maintenance requirements, and upgrades are needed to ensure ongoing safety. Operation, surveillance, maintenance, and monitoring activities are recurring activities that will continue until the buildings are decommissioned or turned over for commercial reuse.

Rocky Flats is organized into 51 scheduling/transfer units. Thirteen major scheduling/transfer units encompassing the plutonium processing and production buildings constitute almost all of the site's stabilization and deactivation costs. The remaining 38 scheduling/transfer units comprise administrative support and ancillary buildings, trailers, and tents, whose associated stabilization and deactivation costs are not included in this estimate because they account for less than one percent of the total stabilization and deactivation cost. A brief description of each of the major scheduling/transfer units is provided below:

886 Nuclear Safety Facility - Building 886 was used to conduct critical mass experiments to support the nuclear safety program at the site. Ancillary buildings include T760B, 828, 875, 880, T886A, T886B, T886C, and 888.

444 Manufacturing Facility - Building 444 is a manufacturing building for depleted uranium, beryllium, and stainless steel component fabrication and assembly. Building 444 is classified as a nonreactor support facility because the facility contains and processes depleted uranium. Ancillary buildings include 427, 439, T439A, T439D, T444A, 445, 446, 447, T447A, 448, 449, 450, 451, 453, 454, 455, 457, 461, and 462.

991 Production Warehouse - Building 991 received, stored, packaged, and shipped all types of product-oriented radioactive, nonradioactive, and nonradioactive hazardous materials. Deliveries were received from onsite and offsite. Ancillary buildings include 967, 968, 980, 984, 985, 989, 996, 997, 998, and 999.

779 Plutonium Development - Building 779 was Rocky Flats' principal plutonium process development laboratory. Building 779 includes specialized physical metallurgy, mechanical testing, joining, stockpile evaluation laboratory applications, and Special Nuclear Material storage areas. Ancillary buildings include 7-5, 727, 729, 779, 780, 782, 783, 784, 785, 786, T779A, 780A, 780B, and 787A.

881 Manufacturing/General Support - Building 881 was used primarily to process uranium. It is presently used for nonradioactive metals production and general site administration. Ancillary buildings include 881F, 881G, 882, 885, 887, and 890.

707 Production Building - Building 707 housed the plutonium manufacturing facility, including foundry operations; metal rolling, forming, heat treating, and debrimming operations; machining operations; chip burning facilities; inspection operations; nondestructive testing operations with X-ray facilities; assembly operations; and various other operations required in plutonium trigger manufacturing and assembly operations. Ancillary buildings include T707B, T707S, 708, 709, 711, 711A, 717, 718, 731, 763, and 778.

771 Plutonium Recovery Facility - Building 771 was Rocky Flats' plutonium recovery process facility. Building 771's previous operations included management of the plutonium aqueous recovery facility, the alloy leaching facility, the processing line for laboratory waste, the (nonoperational) incinerator facility, various storage and plutonium pressing areas, analytical laboratory areas, and research and development areas. Ancillary buildings include 262, 714, 714A, 714B, 715, 715A, 716, 717, 728, 770, 771A, 771B, 771C, T771A, T771B, T771C, T771D, T771E, T771F, T771G, T771H, T771I, T771J, T771K, T771L, 772, 772A 774, 774A, 774B, and 775.

883 Rolling and Forming Facility - Building 883 is a metal rolling and forming building for the processing of depleted uranium, stainless steel, and other nonradioactive materials. Building 883 is classified as a nonreactor nuclear support facility because it contains and processes uranium parts for defense applications. The only ancillary building to 883 is 879.

776/777 Manufacturing/Assembly - Building 776 was the sites' plutonium production, processing, and waste management facility. Building 777 contains nondestructive testing disassembly operations, waste storage, welding, and pressure testing. Ancillary buildings include 701, 702, 703, 710, 712, 712A, 713, 713A, 730, and 781.

865 Metallurgy/Process Development - Building 865 is a development and production support building with an emphasis on stainless steel, beryllium, and depleted uranium. Building 865 is classified as a nonreactor nuclear support facility because the facility contains and processes depleted uranium. Ancillary buildings include 827, 863, 865A, 866, 867, and 868.

371 Plutonium Recovery Building - Building 371 and its ancillary buildings were originally designed to house the physical and chemical operations for recovering and refining plutonium metal and americium oxide. Building 371 contains Special Nuclear Material storage areas and waste and residue storage and may be used for the processing of residues or consolidation of Special Nuclear Material. Ancillary buildings include 223 Tank, 231A, 231B, T371H, T371J, T371K, 373, 374, 376, T376A, 377, 378, 381, 383, and 384.

559 Plutonium Analytical Lab - Building 559 is a nonreactor nuclear analytical laboratory, whose primary purpose is to provide Rocky Flats with timely, cost-effective spectrochemical, chemical and mass spectrometric support for plutonium operations. Building 559 operates as a category III facility, limited to less than 2,000 grams (4.4 pounds) of plutonium. Ancillary buildings include 528, 557, 560, 561, 562, 563, 564, and 732.

460 Manufacturing Facility - Building 460 is a modern nonnuclear manufacturing facility for fabricating reservoirs, tubes, and nonfissile pit components. The building has never processed any Special Nuclear Material, depleted uranium, or beryllium. There are no ancillary buildings associated with this scheduling/transfer unit.

PRE-STABILIZATION SURVEILLANCE AND MAINTENANCE

Buildings that will be shut down remain staffed to accomplish building baseline activities. These activities are designed to maintain compliance with operational safety requirements, environmental regulations, and waste management requirements. Management, operations, facility-specific training, and maintenance activities all support compliance with these requirements and provide general building support in the areas of health and safety operation; nuclear safety; technical, administrative and custodial support; utility services; and waste management activities.

These activities involve all site facilities that were used for nuclear and nonnuclear weapons production, recovery processes, research and development, laboratory activities, calibration and monitoring, and maintenance and support, as well as those facilities that contained radioactive or hazardous materials.

STABILIZATION

Stabilization activities include Special Nuclear Material consolidation and repackaging, removal of plutonium holdup, residue stabilization, and removal of material such as waste and chemical supplies. Stabilization impacts all facilities involved in the processing of radioactive or hazardous materials.

Special Nuclear Material Consolidation and Repackaging

To clean up the site and convert it to another use, Special Nuclear Material must be removed from the individual buildings and either shipped offsite or consolidated into a minimal number of locations. To allow for consolidation of the Special Nuclear Material, building modifications must be completed or a new facility must be constructed. More than 2,000 items must be shipped to the Oak Ridge Reservation, Savannah River Site, and Los Alamos National Laboratory. Also, a significant amount of waste storage capacity, including permitted transuranic mixed and low-level mixed waste storage space, must be eliminated to accommodate consolidation. Consolidation of Special Nuclear Material into Building 371 is expected to be completed in FY 2000. Special Nuclear Material consolidation will allow the Protected Area to be downsized, thereby reducing annual operating costs by reducing the need for safeguards and security and building baselines in various facilities. In addition, consolidation of Special Nuclear Material will allow easier access for remediation of the Industrial Area.

Plutonium metal and oxides are located in Buildings 371, 559, 707, 771, 776/777, 779, and 991. Enriched uranium metal and oxides are located in Buildings 371, 707, 777, 779, 886, and 991. Plutonium metal forms include buttons, ingots, finished and semi­fabricated weapons parts, pits, scrap, scrub alloy, and samples. Plutonium oxide forms include oxide from various processes and samples. Enriched uranium solid forms include weapons parts and experiment parts. Packaging configurations for these materials vary. The materials are stored in gloveboxes, other low­oxygen enclosures, and vaults.

Management objectives for these materials include near­term processing to stabilize and repackage, consolidation within a single building for interim storage, long­term repackaging to bring them into compliance with the Department of Energy standard 50­year storage configuration, and shipping to other the Department of Energy sites as required.

Plutonium Holdup

Plutonium operations were discontinued in 1989. Some glovebox exhaust systems contained more than the recommended levels of fissile material, and the operations curtailment continued until hazards associated with duct material were adequately characterized and evaluated. Some of these ducts have been remediated, and others have been evaluated to demonstrate that they do not pose any significant hazard in their present condition. Ducts will be evaluated to establish their safe condition and then they will be removed and dispositioned during the decontamination and decommissioning of each building. In the interim, safety evaluations will identify the conditions and controls necessary to maintain the material safely in the ducts.

Residue Generation and Handling

Residues include plutonium-contaminated scrap materials or process byproducts once held in reserve at the site pending plutonium recovery operations. Residues are now considered waste because the current plutonium stockpile is sufficient. Mixed residues are residues with a hazardous waste constituent/characteristic and must be managed in accordance with both appropriate radioactive waste regulations and hazardous waste regulations.

Residue Treatment

The Nuclear Material and Facility Stabilization program manages residue treatment, after which the generated waste is handed off to the Waste Management program for storage and disposition. In 1994, the Defense Nuclear Facilities Safety Board prepared a set of recommendations for management of residues. The principal recommendation, 94-1, requires that potentially unstable residues be processed as soon as possible and rendered safe for interim storage. This recommendation includes a three-year time frame to convert materials for safe interim storage and requires that all material meet long-term storage standards within eight years. This report assumes compliance with the Defense Nuclear Facilities Safety Board recommendation, and all residues will be stabilized and converted to transuranic mixed, transuranic, low-level mixed, and low-level waste in preparation for achieving the appropriate waste acceptance criteria and eventual disposal.

Solid Residue Stabilization

Solid residues are byproducts of historical plutonium operations and are categorized into 97 types. Typical residues are metal, glass, graphite, crucibles, salts, combustibles, filters, gloves, ion exchange resins, incinerator ash, and sludge. The composition of residues ranges from about 0.1 percent to 80 percent plutonium, with an average concentration of 3 percent. Approximately 840 cubic meters (1,100 cubic yards) of residues are currently stored in 208-liter (55­gallon) drums, 38-liter (10­gallon) drums, or 1­ and 2­liter (1- and 2-quart) stainless steel cans. Residue storage locations include Buildings 371, 707, 771, 776, 777, and 779. Approximately 433 cubic meters (567 cubic yards) of the residues are categorized as mixed residues; that is they are contaminated with Resource Conservation and Recovery Act­regulated hazardous constituents or exhibit hazardous characteristics.

The objectives for stabilizing solid residues involve eliminating the cause of drum pressurization and hydrogen gas buildup, and eliminating or neutralizing ignitable, reactive, toxic, corrosive, or shock­sensitive materials. The stabilized materials will then be packaged to meet Waste Isolation Pilot Plant Waste Acceptance Criteria and will be sent to the Waste Isolation Pilot Plant for disposal.

Liquid Residue Stabilization

Liquid residues, consisting of approximately 30,000 liters (7,700 gallons) of plutonium-bearing solutions, are currently stored in tanks and process lines at the site, primarily in Buildings 771 and 371. This amount includes various four­liter (one­gallon) bottles stored in Buildings 371, 559, 776, 777, and 779. Before the 1989 curtailment of plutonium production activities at the site, the Department would have stabilized these solutions through the plutonium recovery or waste treatment processes. When plutonium solution processing was curtailed, solutions were left in various stages of the recovery process equipment, including pipes, tanks, and bottles. There are also 2,700 liters (700 gallons) of highly enriched uranium-bearing solutions (uranyl nitrate) stored in tanks in Building 886. Removal of these solutions will eliminate nuclear safety risks, significantly reduce worker safety risks, and reduce the level of security and surveillance required in Building 886.

The objectives for the solution stabilization program involve eliminating plutonium-bearing solutions by converting them to a more stable solid form. Treatment for solutions containing greater than six grams per liter (six grams per quart) plutonium will include precipitation of plutonium followed by cementation of filtrates and thermal stabilization of the resulting plutonium oxide precipitate. Solutions with less than six grams per liter (six grams per quart) plutonium will be cemented directly. The resulting plutonium oxide will be stored, and cemented solutions will be stored as either transuranic waste pending shipment to the Waste Isolation Pilot Plant or as low-level mixed waste. Any sludges that may be generated will be stored until a process for treating them is developed. The highly enriched uranyl nitrate solutions will be converted to a solid uranium oxide for storage, pending disposition decisions.

POST-STABILIZATION SURVEILLANCE AND MAINTENANCE

Facility surveillance and maintenance, environmental monitoring, and other essential support activities occur during the post-stabilization period as required to protect the safety and health of the workers, the public, and the environment.

DEACTIVATION

Deactivation prepares any facility, area or scheduling/transfer unit for decontamination and decommissioning or some other use such as commercial reuse. Deactivation will reduce risks associated with the areas. As a result, baseline costs will be reduced through the eventual elimination of surveillance and maintenance activities. Activities included under deactivation include de-energizing electrical and pressure sources, isolating and/or removing gloveboxes, and process-line draining and isolation. Deactivation activities are required for surplus buildings, equipment systems, modules, and other ancillary structures.

The major uncertainty of the deactivation, decontamination, and decommissioning activities involves time phasing and lack of definition of a formal end state. Decisions concerning long-term site and facility use may develop, and may modify these plans. The systems configuration changes and level of encapsulation will be determined by the scope of the requested deactivation.

POST-DEACTIVATION SURVEILLANCE AND MAINTENANCE

After deactivation, this report assumes that individual facilities will be transferred to the Environmental Restoration program for decommissioning and final disposition. Costs in this category include activities required to maintain facilities prior to their transfer for decommissioning.

Nuclear Material and Facility Stabilization Activities Cost Estimate

(Five-Year Averages, Thousands of Constant 1996 Dollars)
	FY 1996-2000	2005	2010	2015	2020	2025	2030
Pre-Stab. Surveil. and Maintenance	10,296	7,864	4,510	2,133	711
Stabilization	180,916	112,075	96,170	56,537	51,337	9,500	5,700
Post-Stab. Surveil. and Maintenance	2,880	2,850	2,850	2,850	2,850	2,850	2,850
Deactivation	464	1,998	7,734	17,134	6,422	12,100	2,604
Post-Deact. Surveil. and Maintenance		267	416	2,473	1,129	1,897	111
Direct Program Management/Support	46,840	40,000	30,000	30,000	20,000	20,000	20,000
Total	241,396	165,054	141,680	111,127	82,448	46,346	31,264
	FY 2035	2040	2045	2050	2055	2060	2065	Life Cycle*
Pre-Stab. Surveil. and Maintenance								127,570
Stabilization								2,561,172
Post-Stab. Surveil. and Maintenance	2,850	2,280						125,550
Deactivation		396						244,260
Post-Deact. Surveil. and Maintenance	380							33,359
Direct Program Management/Support	6,000	6,000	6,000	6,000				1,154,200
Total	9,230	8,676	6,000	6,000				4,246,111
* Total Life Cycle is the sum of the annual costs in constant FY 1996 dollars.

The following table summarizes the approximate life-cycle volumes of waste generated by Nuclear Material and Facility Stabilization Operations that will be transferred to the Waste Management program for disposal.

Direct Program Management/Support

Direct program management support assures compliance with existing agreements and reduces the risk and costs associated with management of the inventory of Special Nuclear Material. Program management activities include assessment and response to recent regulatory changes, exploration of regulatory flexibility, development of strategies and planning baselines, and tracking and reporting on budgets and performance.

ENVIRONMENTAL RESTORATION

The primary objective of the Environmental Restoration program at Rocky Flats is to assess and clean up the site in compliance with applicable environmental laws and regulations. Environmental restoration activities include characterizing the extent and nature of contamination and its potential risks; removing and/or stabilizing contaminant sources; remediating contaminated soils, ground water, and surface water; decontaminating and decommissioning surplus facilities; and conducting surveillance and post-closure monitoring activities. Rocky Flats was placed on the National Priorities List in 1989. See the Site Map for environmental restoration activity locations.

As noted in the Facility Mission section, the regulatory driver at Rocky Flats is the Interagency Agreement. The Interagency Agreement established specific milestones and time frames for remedial actions, as well as penalties for noncompliance with the agreement. This agreement established parameters for cleanup of potential radioactive, hazardous, and mixed waste contamination resulting from past operations at Rocky Flats at the original 177 Individual Hazardous Substance Sites. Rocky Flats prioritized the original 177 inactive Individual Hazardous Substance sites into 16 operable units. The operable units form the basis for planning, scheduling, budgeting, and prioritizing environmental restoration activities.

The remediation of Rocky Flats's 16 operable units will generate a variety of waste contaminated with hazardous and radioactive substances, including waste derived from investigative activities (for example, soils and pond sludge). Many of these remediation activities will generate secondary waste streams, which will require follow-up treatment, storage, and disposal.

Treatment, storage, and disposal activities for environmental restoration include designing and constructing treatment, storage, and disposal facilities, including: (1) a soil washing facility, (2) a site-wide treatment facility, (3) decontamination pad upgrades, (4) an interim bulk storage facility, (5) an Investigatively Derived Material storage facility, (6) a pre-filtration facility, and (7) an onsite Corrective Action Management Unit.

Major Environmental Restoration Activity Milestones

TASK	COMPLETION DATE Fiscal Year
881 Hillside
Assessment	1996
903 Pad, Mound, and East Trenches
Assessment	2001
Remedial Action	2002
Offsite Areas
Assessment	1997
Solar Ponds
Remedial Action	2000
Corrective Action Management Unit Woman Creek
Assessment	2002
Walnut Creek
Assessment	1998
Present Landfill
Remedial Action	1998
Industrial Area
Assessment	1998
Remedial Action	2015
West Spray Field
Assessment	1996
Inside Building Closures
Assessment	1996
Decommissioning	2055
Long-Term Surveillance and Monitoring	2055

Operable Unit 1 - 881 Hillside

Operable Unit 1, composed of 11 Individual Hazardous Substance Sites, is located at the 881 Hillside Area north of Woman Creek in the southeast section of Rocky Flats, approximately 3.2 kilometers (2 miles) from the eastern outer edge of the buffer zone at Indiana Street. Isolated areas of the shallow ground water were contaminated in the 1960s and 1970s with solvents and radionuclides. Operable Unit 1 has been treated as a high-priority Operable Unit because of potentially elevated concentrations of organic compounds in the near-surface ground water and the proximity of the contaminants to the Woman Creek drainage system. Until the Woman Creek Reservoir was completed, diverting water from Woman Creek, Woman Creek led to Standley Lake, which is an offsite drinking water supply for the city of Westminster.

The contaminants found in Operable Unit 1 include volatile organic compounds, carbon tetrachloride in ground water, and polycyclic aromatic hydrocarbons in surface soils. Plutonium has been found in an isolated location and removed by means of an Accelerated Response Action completed in October 1994. The Preferred Alternative for Operable Unit 1 is soil excavation and ground-water pumping. Surface soil polycyclic aromatic hydrocarbon contamination is estimated to cover approximately 3,700 square meters (40,000 square feet). Ground water requiring treatment is being collected at less than 4 liters (1 gallon) per minute. The types of media that have been contaminated include alluvial soils and ground water. Ground-water contamination with volatile organic compounds is localized. Local geologic features and sparse occurrence of actual ground water have minimized migration.

ASSESSMENT

The Department has completed three-phased remedial investigations. The Final Phase II remedial investigation report was submitted to the regulatory agencies in June 1994. The remedial investigations indicated the presence of volatile organic compounds in the soils. The Final Feasibility Study and Draft Proposed Plan for Operable Unit 1 were submitted in February 1995 and May 1995 respectively. The Final Record of Decision is planned to be submitted by June 1996.

REMEDIAL ACTION

An interim remedial action at Operable Unit 1 involved constructing an underground drainage system (French drain) that intercepts and contains near-surface ground water flowing from the 881 Hillside Area. The interim remedial action construction has been completed.

The ground water collected as part of the interim remedial action is treated with an ultraviolet/peroxide system at the Building 891 treatment facility and then released into the Sound Interceptor Ditch above Woman Creek. The treated water meets Safe Drinking Water Act standards.

Operable Unit 2 ­ 903 Pad, Mound, and East Trenches

Operable Unit 2 includes 20 Individual Hazardous Substance Sites located in the east Buffer Zone, 903 Pad, and the Mound Area. Contamination resulted from leaking drums, drum storage spills, oil burning residues, pallet burning residues, flattened­drum disposal, sewage sludge disposal, plutonium- and uranium-contaminated waste disposal, and surface water runoff from the Protected Area. Volatile organic compound contaminants (trichloroethane, tetrachloroethylene, and carbon tetrachloride) have been identified in a ground-water plume that covers approximately 513,333 square meters (5,500,000 square feet). This report assumes that approximately 24,427 cubic meters (32,000 cubic yards) of soil are contaminated by low concentrations of uranium, plutonium, and americium. No stabilization or decommissioning activities are required for Operable Unit 2.

ASSESSMENT

The Phase I remedial investigation has been completed and Phase II field investigations are complete. One hundred one ground-water monitoring wells were installed for the alluvial field investigations. Seven wells were installed for the bedrock phase of the investigation. A portion of the surface water contamination is caused by a seep; if not collected, water from the seep eventually flows to Walnut Creek and then to a series of retention ponds. Water in the pond is sampled and treated, if needed, prior to release to ensure compliance with Rocky Flats' current National Pollution Discharge Elimination System permit and other applicable standards. The final remedial investigation report was submitted to the agencies in October 1995. The initial draft Record of Decision is planned for submittal in August 1997.

REMEDIAL ACTION

The Operable Unit 2 South Walnut Creek interim remedial action document of March 1991, was approved by Environmental Protection Agency and the Colorado Department of Public Health and Environment in May 1991. This document required collection, treatment, and disposal of surface water from three locations in the Operable Unit. Phase I of this project included water collection from two locations, storage, and organics removal using granular activated carbon. It was completed on an expedited basis to meet the May 1991 Interagency Agreement milestone. The installation of a water collection system for the third location and radionuclides removal system (Phase II) was completed in April 1992. The system is expected to remain in service until the final remedial action is concluded. By the end of 1994, the Operable Unit 2 Surface Water interim remedial action field treatment unit had treated approximately 94,000,000 liters (24,800,000 gallons) of surface water collected from the seep stations. Sampling was reduced at the field treatment unit because most of the extensive and costly sampling was performed to support the Final Phase II treatability study report completed in January 1994. The water treatment unit for Operable Unit 2 is being combined with that of Operable Unit 1, eliminating the necessity for a field treatment unit.

A second interim remedial action was a pilot test to evaluate soil vapor extraction, a technology for remediating subsurface contamination, which is located north of Woman Creek and encompasses the 903 Pad, the Mound Area, and the East Trenches of Operable Unit 2. This interim remedial action plan/Environmental Assessment identified and evaluated the effectiveness, ability to implement, and cost of soil vapor extraction as an interim remedial action for removal of residual volatile organic compound contamination from subsurface environments at Operable Unit 2. The pilot was completed in FY 1995.

The final remedial action to be implemented at Operable Unit 2 will be determined after assessing the remedial investigation findings and the interim remedial action treatment technologies as part of the feasibility studies. This report assumes that ground-water contamination will be treated with one or a combination of granular activated carbon units, an ultraviolet/peroxide system, ion exchange, and/or a chemical precipitation/flocculation/filtration process as part of a site-wide ground-water management strategy.

This report assumes that soils contaminated with organics and metals will be excavated and removed to the Corrective Action Management Unit. Soils contaminated with radionuclides may be excavated, thermally desorbed to eliminate volatile organic compounds, and relocated to onsite soil stabilization/solidification facilities for crating prior to being shipped to the Nevada Test Site for disposal. "Ryan's Pit" was excavated in September 1995 and treated by thermal desorption in January 1996. Trenches T­1 and T­2 will be excavated and treated in 1996.

Operable Unit 3 ­ Offsite Areas

Operable Unit 3 encompasses approximately a 100-square-kilometer (38-square-mile) area north, south, and primarily east of Rocky Flats. The area west of the site is generally considered to represent background conditions because it is upgradient from the prevalent wind direction, and upgradient with respect to surface water drainage patterns. For these reasons the areas west of Rocky Flats are not generally considered to be part of Operable Unit 3. Operable Unit 3 consists of four Individual Hazardous Substance Sites: Individual Hazardous Substance Site 200, Great Western Reservoir; Individual Hazardous Substance Site 201, Standley Lake; Individual Hazardous Substance Site 202, Mower Reservoir; and Individual Hazardous Substance Site 199, the surrounding surficial soils.

Two events represent the primary sources of contaminant release to Operable Unit 3. From 1958 to 1969, the 903 Pad was used as a storage site for 55 gallon drums containing plutonium-contaminated lathe coolant. Exposed to the elements, these drums corroded and subsequently leaked their contents onto the surrounding soils. Wind erosion and resuspension distributed these contaminated soils in a generally eastward­trending plume that extended beyond the site boundary onto offsite areas east of Indiana Street. Efforts to mitigate this contaminant source involved the removal of contaminated soils at the 903 Pad, placement of an asphalt cap over the previous storage area, and deep­disc plowing of soils immediately east of the Rocky Flats east gate. The second significant event contributing to offsite contamination occurred from 1970 to 1973, during which sediments from the Walnut Creek A and B series retention ponds were released during a reengineering project. These sediments were suspended during construction and subsequently flowed into the Great Western Reservoir.

ASSESSMENT

The Operable Unit 3 Remedial Investigation is in its final stages. The draft remedial investigation results were submitted to the regulatory agencies in October l995 for their review and comments. Results of the draft remedial investigation indicate that the extent of contamination can be well-defined as a plume that trends from, and is attributable to, wind resuspension of contaminated soils from the 903 Pad.

Contamination in the reservoirs is contained within the reservoir sediments. The maximum activities are found in the subsurface sediments in the deepest portions of Great Western Reservoir. Risk associated with exposure to these sediments does not exceed the Environmental Protection Agency public health guidelines.

The results of the Operable Unit 3 draft remedial investigation show that the risks to offsite neighbors of Rocky Flats do not exceed human health based standards set by the Environmental Protection Agency and the Colorado Department of Public Heath and Environment. Given the low risk values for the soils and Great Western Reservoir, and the most likely current and future land-use scenarios, further investigation or remedial action is not warranted to be protective of human health and the environment. The next phase for Operable Unit 3 is the development of a Proposed Remedial Action Plan for public review and comment. This plan will provide the basis for an expected No Action Record of Decision.

Operable Unit 4 ­ Solar Ponds

Operable Unit 4 includes five solar evaporation ponds located in the northeast part of the site's Protected Area. The Solar Ponds were used primarily for the treatment of low­level waste contaminated with nitrates and radionuclides. Other materials, such as aluminum and lithium scrap, sewer sludge, cyanide, acid waste, and landfill leachate, were placed in the ponds on a nonroutine basis. Contaminated ground water was collected downgradient of the ponds and placed in the ponds until April 1993. Contaminated soils also exist in Operable Unit 4. All placement of materials into the ponds has stopped.

The solar ponds were estimated, in the first quarter of FY 1995, to contain a combined total of approximately 1,330,000 liters (350,000 gallons) of sludge and water. Currently, the ponds are empty, and the sludge is stored and awaiting treatment. The quantity of underlying contaminated soil has not been fully determined. For estimating purposes, this report assumes slightly less than 153,000 cubic meters (200,000 cubic yards). The ground-water plume extends north approximately 0.4 kilometers (0.25 mile). The extent of the soil contamination is localized near the Solar Ponds.

ASSESSMENT

The nature and extent of the contamination will be confirmed during the remedial investigation process. Currently, a Resource Conservation and Recovery Act ground-water monitoring well network is in place. The data collected from these wells and the Interceptor Trench System aided the characterization of ground water.

REMEDIAL ACTION

A decision for Operable Unit 4 is expected by mid­year FY 1996. The assumed approach for solar ponds remedial action is to excavate and treat the soil as low-level mixed waste. Once the soil is excavated, a Corrective Action Management Unit will be built in the area of the existing ponds. All low-level mixed and low-level waste, including the excavated soil, will be placed in the Corrective Action Management Unit. Land Disposal Restricted Saltcrete will be shipped to Envirocare of Utah for disposal. Remedial activities will be completed by FY 2000.

Corrective Action Management Unit

As noted above, this report assumes that a disposal facility will be constructed at the solar ponds site after remedial action is complete. The facility will be designed to meet Resource Conservation and Recovery Act performance standards. It will be composed of two adjacent disposal cells: an Environmental Restoration-funded and operated Corrective Action Management Unit for remediation waste; and a Waste Management-funded and operated Resource Conservation and Recovery Act Subtitle C disposal cell for pondcrete.

Most low-level mixed, low-level, and hazardous waste, approximately 35,000 cubic meters (45,850 cubic yards), generated from environmental restoration activities will be placed in the Corrective Action Management Unit, which will become available in FY 1997 and operate until it reaches full capacity in FY 2002. The bulk of the waste disposed in the Corrective Action Management Unit will be soil and debris. After reaching full capacity, the entire disposal facility will require 30 years of monitoring, ending in FY 2041.

Operable Unit 5 ­ Woman Creek

Operable Unit 5 comprises 11 Individual Hazardous Substance Sites along the Woman Creek Drainage on the south side of Rocky Flats: the Original Landfill, the Ash Pits, the Incinerator, the Concrete Wash Pad, and Detention Ponds C­ 1 and C­2. The Historical Release Report identified potential contaminants to date including solvents, paints, paint thinner, oil, pesticides, cleaners, beryllium, depleted uranium, ash from plant waste, metals, radium, nitrates, and nonradioactive hazardous chemical waste. The sources of the contaminants are general site waste, ash from burning of Rocky Flats waste and depleted uranium, and surface water runoff. The quantity of contaminated soil, sediments, ground water, air, and surface water will be determined from the results of the Phase I remedial investigation.

ASSESSMENT

Field sampling work investigated the potential contaminants. The extent of potential contamination includes the following approximations: 3 hectares (7.5 acres) at the landfill, 15,200 cubic meters (19,900 cubic feet) at the ash pits, and 8 kilometers (5 miles) of stream sediments and soils along Woman Creek. To date, the Department has installed 96 wells, drilled 101 boreholes, and collected sediment and surface water samples. Both the human­health risk assessment and the ecological risk assessment concluded that risks are below levels of regulatory concern. Assessment activities include preparing and submitting the remedial investigation report planned for April, 1996; the feasibility study planned for FY 1997; and the Record of Decision planned for FY 1997. This report assumes that the Record of Decision will require No Further Action.

Operable Unit 6 ­ Walnut Creek

Operable Unit 6 comprises 19 Individual Hazardous Substance Sites in the Walnut Creek drainage: A­series detention ponds (A­1 through A­4); B­series detention ponds (B­1 through B­5); the North and South Spray Fields, the East Area Spray Fields; Trenches A, B, and C; the Sludge Dispersal Area; the Triangle Area; the Old Outfall Area; and the Soil Dump Area. Potential contaminants of concern include plutonium, americium, uranium, metals, nitrates, strontium, polychlorinated biphenyls, volatile organic compounds and polycyclic aromatic hydrocarbons. It is currently estimated that a maximum of 247,000 cubic meters (323,000 cubic yards) of soil, 201 million liters (53 million gallons) of water, and 12 kilometers (7. 5 miles) of stream bed are contaminated.

ASSESSMENT

The draft final Remedial Facility Investigation/Remedial Investigation Report was delivered to the Environmental Protection Agency and the Colorado Department of Public Health and Environment at the beginning of FY 1996. The summary of the Baseline Risk Assessment indicated that there is a lack of risk to human health and the environment. The final Phase I report was due to the Environment Protection Agency and the State of Colorado on February 21, 1996. After responses to the regulatory agency comments were accepted and the final Phase I report was approved, Operable Unit 6 was to be divided and reconsolidated into different operable units. This report assumes that each Individual Hazardous Substance Site will eventually be closed through a No Action Record of Decision.

Operable Unit 7 ­ Present Landfill

Operable Unit 7 comprises four Individual Hazardous Substance Sites associated with the disposal and storage operations at the present landfill. Based on historical records, the present landfill received nonhazardous solid waste and solid waste streams that contained hazardous waste or hazardous constituents. The potential contaminants include radionuclides, volatile and semi-volatile organics and metals. The extent of contamination includes the area of the landfill, source-area ground water, leachate/ground water that has migrated from the source area, surface water in the East Landfill pond, and surficial soils that were sprayed with the East Landfill pond water. The evaluation of the Phase I Remedial Investigation results indicates the following estimated quantities of contaminated media: landfill waste ­ 220,000 cubic meters (290,000 cubic yards); daily interim soil cover - 95,000 cubic meters (125,000 cubic yards); landfill gas ­ 73,000 cubic meters (95,000 cubic yards); source-area ground water, leachate/ ground water ­ 19 million liters (5 million gallons); East landfill pond ­ 19 million liters (5 million gallons); and East Landfill pond sediments ­ 3,000 cubic meters (4,000 cubic yards). No stabilization or decommissioning activities are planned for Operable Unit 7.

ASSESSMENT

The Operable Unit 7 area of investigation was characterized during the Phase I and Phase II remedial investigations. The Phase I and II remedial investigation identified the potential contaminates of concern in soil, surface water, and ground water to include radionuclides, hazardous substances (volatile and semi-volatile organic compounds) and metals.

REMEDIAL ACTION

A cover meeting the permeability requirements of the subsurface soils will be placed over the landfill as an interim remedial action. A barrier to minimize the recharge of the landfill mass from upgradient ground water will be installed. Remedial action outside the landfill source area depends on focused risk­assessment findings. All investigation derived material, and accelerated and interim construction debris will be placed beneath the landfill cover.

Operable Units 8, 9, 10, 12, 13, and 14 - Industrial Area

The Industrial Area (Operable Units 8, 9, 10, 12, 13, and 14) has been consolidated and managed as a unified project because the scope of work and logistical approach for the six inclusive operable units is similar. This approval uses resources more efficiently and focuses the individual operable unit investigations on implementing field activities. The Industrial Area comprises 93 Individual Hazardous Substance Sites as summarized below:

Operable Unit 8, the 700 Area, comprises 24 Individual Hazardous Substance Sites inside and around the former production areas in the 700 Area at Rocky Flats. Identified contaminants include solvents spills, such as carbon tetrachloride and benzene. Additional contaminant sources include process wastewaters, acids, bases, oils, nitrates, metal, and radionuclides (plutonium, americium, and uranium), sewage effluent, sewer line breaks, and petroleum products.

Operable Unit 9, Original Process Waste Lines, comprises 21 Individual Hazardous Substance Sites. Contaminant sources include leakage from 8,900 linear meters (35,000 linear feet) of process and effluent pipelines, 72 storage tanks (above and below ground), valve vaults, and process waste spills. The extent of soil contamination associated with each Individual Hazardous Substance Site is unknown until the Phase I remedial investigation is complete. The volume of contaminated soil to be removed is estimated to be 7,916 cubic meters (10,370 cubic yards), assuming a depth of 1.8 meters (6 feet) for each Individual Hazardous Substance Site.

Operable Unit 10, Other Outside Closures, comprises 15 Individual Hazardous Substance Sites, 13 of which are scattered throughout the Industrial Area and two within the Buffer Zone near the present landfill as a result of the physical setting of the Individual Hazardous Substance Site, hydrogeological setting, and effects of ground-water migration. Contaminants identified include radionuclides, volatile organic compounds, metals, halogenated and nonhalogenated solvents, cyanide, petroleum products, and acids. The total quantity of media requiring remediation will not be know until the Phase II remedial investigation is complete. Sources of contamination are tanks (above ground), waste storage areas, acid dumps and dumpsters, container storage areas, pondcrete and saltcrete storage areas, and drum storage area as identified by process knowledge and historical records.

Operable Unit 12, the 400/800 Area, comprises ten Individual Hazardous Substance Sites located in and around the 400 and 800 Areas of Rocky Flats: Multiple Solvent Spills at the West and South Loading Dock areas; Fiberglassing Areas North and West of Building 664; Cooling Tower Ponds ­ northeast of Building 460; Building 881 ­ Conversion Site; Radioactive Site ­ South Area; Acid Leaks; and Multiple Acid Spills. Possible contaminants are plutonium, uranium, metals, acids, oils, chlorinated hydrocarbon solvents, nitrates, sulfates, lithium, beryllium, unspecified cleaning solvents, and hydrogen peroxide catalyst materials. The Phase I remedial investigation will determine the volume of contaminated media.

Operable Unit 13, the 100 Area, comprises 15 Individual Hazardous Substance Sites located within the 100 Area of Rocky Flats. Based on historical reports and process knowledge, suspected contaminants may include plutonium, uranium, depleted uranium, metals, oils, soaps, solvents nitrates, lithium, beryllium, fuel oils and unknown chemicals, along with sodium hydroxide. The potential for discovery of additional unknown chemicals is low. These contaminants may have originated from old processing facilities, solvent spills, burn pits, fuel tank spills, lithium metal destruction, and leaking drums. It is assumed that contamination is localized in areas where leaks/spills have occurred, and the geologic and hydrogeologic composition of the area has contributed to the migration of the contaminants. The exact quantity of contaminated material is as yet undefined. The estimated volume of potentially contaminated soils is 81,370 cubic meters (106,600 cubic yards) based on the contamination present to an average depth of one and one-half meters (five feet).

Operable Unit 14, the Radioactive Sites, comprises eight Individual Hazardous Substance Sites located throughout the industrial area. Contaminants may include radionuclides, volatile organic compounds, and metals. Surface soils, asphalt, and concrete may be contaminanted based on historical information and preliminary fieldwork. Historical reports and source information indicate that approximately 105,923 cubic meters (138,759 cubic yards) of soil may be contaminated. Subsurface soils, ground water, and building structures are potentially affected where contamination is found. The eight Individual Hazardous Substance Site locations have suspected contaminated soils and ground water, but it is believed that the contamination is confined to localized areas because of accident spills, fires, and construction activities.

ASSESSMENT

The exact quantity of contaminated material is as yet undetermined, but will be defined during the Phase I remedial investigation. Surface soils, asphalt, pipelines, tanks, and concrete may be contaminated, based on historical information and preliminary fieldwork. These contaminants may have originated from old processing facilities, solvent spills, burn pits, fuel tank spills, lithium metal destruction, leaking drums and past practices such as lithium destruction.

Currently, the investigation of the Industrial Area operable units is in the first stages. Investigations include drilling wells and boreholes to sample ground water and soil. Nonintrusive high­purity germanium/Fidler surveys will be conducted, as well as soil gas and surficial soil sampling. Results from these investigations have yet to be interpreted and finalized. The technical memoranda will provide the analysis of field data and recommendations for follow­up investigations and will detail the nature and extent of the contamination discovered. Buried pipelines in Operable Unit 8 will be located and inspected by excavating test pits to expose lines, and by using video cameras and pressure testing devices between test pits where necessary.

REMEDIAL ACTION

This report assumes that all tanks and pipelines in Operable Units 8 and 9 will be removed. An interim remedial action is planned for Operable Unit 10. The extent of the activities will be determined upon completion of the remedial investigations report, but it is expected to include removing soil and treating ground water to reduce the threat to human health and the environment.

This report assumes that Industrial Area ground water contaminated with radionuclides and/or metals will be treated using an ion exchange process or a precipitation/flocculation/filtration process. Water contaminated with organics will be treated with granular activated carbon units or ultraviolet/peroxide processes. Soils contaminated with radionuclides will be excavated and transported to a soil solidification facility or soil washing facility for volume reduction. Soils contaminated with organics and metals will be excavated and relocated to the new onsite Corrective Action Management Unit. Soils contaminated with organics will be treated using an onsite rotary kiln-type technology to remove organics prior to solidification and storage or disposal.

Operable Unit 11 ­ West Spray Field

Operable Unit 11, the West Spray Field, is located in the Rocky Flats Buffer Zone, west of the Industrial Area. At Operable Unit 11, past operational practices included the periodic spraying of excess liquids pumped from the Solar Evaporation Ponds as a means of evaporating waste water. This spraying was conducted between April 1982 and October 1985. The sources of waste water stored in the Solar Evaporation Ponds and sprayed at Operable Unit 11 include effluents from the Sewage Treatment Plant and ground water collected in the Interceptor Trench System. The pond liquids contained elevated levels of nitrates, metals, radionuclides, volatile organic compounds, and semi-volatile organic compounds.

The Record of Decision for Operable Unit 11 was approved in October 1995. The Selected Remedy specified in the Record of Decision is No Action.

Operable Unit 15 ­ Inside Building Closures

Operable Unit 15 comprises six Individual Hazardous Substance Sites located within buildings in which hazardous materials and radionuclides were either stored or processed at Rocky Flats. Contamination may have originated from drum storage areas, the uranium chip roaster, and cyanide bench scale treatment area. Potential contaminants have been identified as waste oil; 1, 1,1-trichloroethane; chlorinated solvents; volatile organic compounds; beryllium; and radionuclides; as indicated by historical reports and preliminary sampling.

The Phase I and Phase II remedial investigations fieldwork was completed in 1994. Technical memoranda addressing field sampling activities and baseline risk assessments were also completed in 1994. The Record of Decision for Operable Unit 15 was approved in October 1995. The Selected Remedy specified in the Record of Decision is No Action.

Section 2