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Record of Decision System (RODS)



Site Name:  HANFORD 100-AREA (USDOE)
Address:  100 AREA 
City & State:  BENTON COUNTY  WA  99352
County:  BENTON
EPA ID:  WA3890090076
EPA Region:  10
NPL Status:  Currently on the Final NPL
ROD Type:  Record of Decision
ROD ID:  EPA/541/R-99/112
ROD Date:  09/29/1999
Operable Unit(s):  08, 09
Media:  Debris, Groundwater, Other, Soil
Contaminant:  Base Neutral Acids, Inorganics, Metals, PCBs, Petroleum Hydrocarbon, Radioactive, VOC
Abstract:  The Hanford Site was established during World War II as part of the "Manhattan Project" to produce plutonium for nuclear weapons. Hanford Site operations began in 1943, with USDOE facilities located throughout the Site and the City of Richland. Certain portions of the Site are known to have cultural significance and may be eligible for listing in the National Register of Historical Places.

In 1988, the Hanford Site was scored using EPA's Hazard Ranking System. As a result of the scoring, the Hanford Site was added to the National Priorities List (NPL) in November 1989 as four sites (the 100 Area, the 200 Area, the 300 Area, and the 1100 Area). Each of these areas was further divided into operable units. The 100 Area NPL site consists of the following operable units for contaminated sources such as soils, structures, debris, and burial grounds: 100-BC-1, 100-BC-2, 100-KR-1, 100-KR-2, 100-NR-1, 100-DR-1, 100-DR-2, 100-HR-1, 100-HR-2, 100-FR-1, 100-FR-2,100-IU-1, 100-IU-2, 100-IU-3, 100-IU-4 and 100-IU-5; for contaminated groundwater: 100-BC-5, 100-KR-4, 100-NR-2, 100-HR-3, and 100-FR-3.

In anticipation of the NPL listing, the Department of Energy (DOE), EPA, and the Washington State Department of Ecology (Ecology) entered into a Federal Facility Agreement and Consent Order in May 1989 known as the Tri-Party Agreement. This agreement established a procedural framework and schedule for developing, implementing, and monitoring remedial response actions at Hanford. The agreement also addressed Resource Conservation and Recovery Act (RCRA) compliance and permitting.

In 1992, the Hanford Future Site working Group evaluated four future land use options for the site and recommended cleanup of sources and contaminated groundwater flow into the Columbia River as an "immediate priority." This recommendation was a key consideration in the selection of high priority liquid radioactive disposal sites for interim remedial actions. The recommendations also expressed a desire for ultimately achieving "unrestricted use" for the air, surface, subsurface, and groundwater, with the exception of the B Reactor as a museum option. That option would place the reactor itself in a "restricted" status.

The Final River Conservation Study and the Environmental Impact Statement for the Hanford Reach of the Columbia River (National Park Service 1994) proposed that the Hanford Reach of the Columbia River and approximately 102,000 acres of adjacent lands be designated as a National Wild and Scenic River and a National Wildlife Refuge, respectively.

On September 27, 1995, the Interim Record of Decision was signed for this site.

DOE performed a 100 area wide phase 1 and 2 Feasibility Study (FS) and operable unit specific Limited Field Investigations for the 100-BC-1, 100-DR-1 and 100-HR-1 operable units. A 100 area-wide Phase 3 Source Waste Site FS and 100 Area operable unit specific Focused FS also were conducted to evaluate specific waste site remedial action goals, objectives and technologies.

The 100-NR-1 OU encompasses an area of approximately 405 hectares (over 1,000 acres) and contains the N Reactor, the Hanford Generating Plant (HGP), and adjacent support facilities. Reactor operations and former waste-handling practices have caused contamination in the soil around the N Reactor, the HGP, and the adjacent support facilities, and in the 100-NR-2-OU.

The 100-NR-2 OU encompasses the contaminated groundwater underlying the 100-N Area. During the years of reactor operations until shortly after reactor shutdown, large volumes of reactor coolant wastewater containing activation and fission products, as well as small quantities of corrosive liquids and laboratory chemicals generated by various N Reactor operations, were discharged to the soil through cribs and trenches. A groundwater pump and treat system has been in operation since September 1995 as part of on expedited response action at the 100-NR-2 OU. This system provides removal of strontium-90 from extracted groundwater, treatment of strontium-90 by ion exchange, and return of treated groundwater to the unconfined aquifer using upgradient injection wells.

Throughout the operational history of the N Reactor, significant spills were documented in unplanned release reports. The unplanned release reports were used for reporting and tracking the activities associated with each spill. Spills in the 100-N Area consisted of three basic types: radioactive, corrosive, and petroleum. Response to unplanned releases or spills depended on the location of the spill, the constituents involved, and the potential impact to worker safety and the environment. Spills that were likely to have an impact on humans or the Columbia River were remediated, to the extent possible, at the time of the spill to mitigate potential impacts.
The Department of Energy, Environmental Protection Agency, and the Washington State Department of Ecology, also known as the Tri-Parties, entered into the Federal Facility Agreement and Consent Order in May 1989. The 100-NR-1 and 100-NR-2 OUs were designated as units subject to Resource Conservation and Recovery Act (RCRA) corrective action. In 1998, DOE published the results of a Corrective Measures Study, that was conducted to gather information to support selection of a remedial alternative to address contamination at the 100-NR-1 and 100-NR-2 OUs. In a addition, a qualitative risk assessment (QRA), comprised of both human health and ecological risk assessments, was conducted to evaluate current and potential effects of contaminants in the 100-NR-1 OU on human health and the environment.

The structures and buildings associated with the 100-NR-1 OU have a Superfund Removal Action Memorandum issued in January 1999 to authorize cleanup of the sites.

A Record of Decision addressing OU8 was completed in September 1999.
Remedy:  The selected remedy for the Source Waste sites will remove contaminated soil, structures, debris, and pipelines to a depth of 15 feet below surrounding grade or to the bottom of the engineering structure, whichever is deeper for the Radioactive, Inorganic, Burn Pit, and Surface Solid Waste Groups. The wastes will be treated to meet Hanford Environmental Restoration Disposal Facility (ERDF) acceptance criteria and soils, structures, debris and pipelines will be disposed of at ERDF. DOE will backfill excavated areas with clean material, grade, and re-vegetate the area, and maintain institutional controls.

For the Petroleum Waste Group with near-surface contamination, DOE will remove contaminated media (soil/debris) down to a depth of 15 feet below surrounding grade or the bottom of the engineering structure, whichever is deeper. DOE may remove contaminated media below 15 feet as necessary if field conditions warrant and the state approves. DOE will ex-situ bioremediate contaminated media within the operable unit boundary. DOE will dispose of residual contaminated media, if required, to a state approved facility. DOE will collect and dispose of leachate to the Effluent Treatment Facility or as approved by the state. DOE will backfill and re-vegetate excavated areas and maintain institutional controls.

For the Petroleum Waste Group with deep contamination, DOE will in-situ bioremediate contaminated media below 15 feet of surrounding grade, bottom of engineering structure, or at the stopping point of ex-situ bioremediation, whichever is greater. DOE will install necessary injection wells and infrastructure and maintain groundwater monitoring wells to monitor bioremediation and impacts to groundwater. DOE will grade and re-vegetate the areas and maintain institutional controls until remediation is complete.

For the Shoreline Waste Group, the selected remedy consists solely of institutional controls.

Institutional controls consist of the following elements: controlled access to the site; an on-site excavation permit process to control well drilling and excavation of soil within the 100 Area operable units to prohibit any drilling or excavation except as approved by the state; maintaining existing signs prohibiting public access to the shoreline site; notification to the state and Benton County Sheriff's Office upon discovery of any trespass incidents; adding access restriction language to any land transfer, sale, or lease of property that the U.S. Government considers appropriate while institutional controls are compulsory, and the state will have to approve any access restrictions prior to transfer, sale or lease.

Until final remedy selection, the Department of Energy (DOE) will not delete or terminate any institutional control requirement established in the Record of Decision unless the state has provided written concurrence on the deletion or termination. DOE will evaluate the implementation and effectiveness of institutional controls on an annual basis. DOE shall submit a report to the state by July 31 or each year summarizing the results of the evaluation for the preceding calendar year.

The selected remedy for the groundwater is continued operation of an existing pump and treat system using an ion exchange resin to remove strontium-90. Petroleum hydrocarbons also have been observed in two monitoring wells and free-floating product will be removed if observed during future monitoring activities.

Estimated Capital Costs: Not Provided
Estimated Annual O&M Costs: $329,100 (groundwater pump and treat)
Estimated Present Worth Costs: $50,257,786
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