Description Report

Site Description

SUPERFUND SITE ID:	1001111	SITE NAME:	HANFORD 300-AREA (USDOE)

Description Text
The 300 Area began as a fuels fabrication complex in 1943. Most of the facilities in the area were involved in the fabrication of nuclear reactor fuel elements. In addition to the fuel manufacturing processes, technical support, service support, and research and development related to fuels fabrication also occurred within the 300 area. In the early 1950's, the Hanford Laboratories were constructed for research and development. As the Hanford Site production reactors were shut down, fuel fabrication in the 300 Area ceased. Research and development activities have expanded over the years. The 300 Area contains a number of support facilities, including a powerhouse for process steam production; a water intake and treatment system for potable and process water; and other facilities necessary for research and development; environmental restoration, decontamination, and decommissioning. In 1988, the Hanford Site was scored using the EPA's Hazard Ranking System. As a result of the scoring, the Hanford Site was listed on the National Priorities List (NPL) in November 1989 under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA). The Hanford site was divided and listed as four NPL Sites: the 100 Area, the 200 Area, the 300 Area, and the 1100 Area. In anticipation of the NPL listing, the U.S. Department of Energy (DOE), the U.S. Environmental Protection Agency (EPA), and the Washington State Department of Ecology (Ecology) entered into the Hanford Federal Facility Agreement and Consent Order ( known as the Tri-Party Agreement, or TPA) in May 1989. This agreement established a procedural framework and schedule for developing, implementing, and monitoring remedial response actions at Hanford. The agreement also addresses Resource Conservation and Recovery Act (RCRA) compliance and permitting. DOE, Ecology, and EPA developed a Community Relations Plan in April 1990 as part of the overall Hanford Site restoration. This plan was designed to promote public awareness of the investigation, as well as public involvement in the decision-making process. The RI/FS reports and the proposed plan for 300-FF-1 and 300-FF-5 were made available to the public in both the Administrative Record and the Information Repositories maintained at various locations. These documents were offered for a 45-day public comment period from December 4, 1995 to January 17, 1996. During that time, an extension of the comment period was requested. The public comment period was subsequently extended to February 9, 1996. A Record of Decision (ROD) was signed for the 300-FF-1 (OU 1) and 300-FF-5 (OU 2) in July 1996. An Explanation of Significant Differences (ESD) was produced in January 2000. This ESD documents a Land Disposal Restriction (LDR) variance for lead in the soil at 300-FF-1. A second Explanation of Significant Differences (ESD) was signed in June 2000. This ESD expanded the boundary of 300-FF-5 to include groundwater beneath all 300-FF-2 waste sites and burial grounds. It also required certain changes be made to the Operation and Maintenance (O&M) plan. The changes were intended to ensure that adequate institutional controls and groundwater monitoring requirements were in place at the site. An interim ROD for 300-FF-2 (OU 3) was signed April 4, 2001. This ROD addressed contaminated soil, solid waste, and debris at 56 sites within the 300 Area. The U.S. Department of Energy's Hanford Site is a 560-square mile federal facility located in southeastern Washington along the Columbia River. The region includes the incorporated cities of Richland, Pasco, and Kennewick (Tri-Cities), as well as surrounding communities in Benton, Franklin, and Grant counties. 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. The 300 Area, which encompasses approximately 1.35 sq km (0.25 sq mi), is adjacent to the Columbia River and approximately 1.6 km (1 mi) north of the Richland city limits. The Hanford Site was divided and listed as four National Priorities List (NPL) Sites: The 100 Area, the 200 Area, the 300 Area, and the 1100 Area. Each of these areas was further divided into operable units, which are groupings of individual waste units based primarily on geographic areas and common waste sources. The 300 Area NPL site consists of the following operable units: 300-FF-1, 300-FF-2 and 300-FF-5. The 300-FF-1 and 300-FF-2 Operable Units (OUs 1 and 2, respectively) address contaminated soils, structures, debris and burial grounds. The 300-FF-5 Operable Unit addresses the groundwater beneath 300-FF-1 and 300-FF-2. The Hanford Site is located in the Pasco Basin, a sediment-filled topographic and structural basin situated in the northern portion of the Columbia Plateau. Water from the Columbia river is also the source of drinking water for the 300 Area. In addition, the Columbia River is used extensively for recreation, including fishing, hunting, boating, sailboarding, water-skiing, diving, and swimming. The 300 Area is generally level, with a steep embankment dropping to the river. The unconfined aquifer beneath the 300 Area is composed of two hydrogeologically distinct formations: the Hanford and the Ringold formations. Flow in the unconfined system is generally toward the Columbia River, and groundwater even tually discharges to the river through springs and seeps in the river bottom and riverbank. The groundwater flow system has a significant impact on the contaminant distribution observed in the aquifer. Higher groundwater pore velocities, associated with the saturated Hanford formation found along the river, will quickly flush and naturally dilute contamination introduced into the aquifer and facilitate its remediation. No plants or mammals on the Federal List of Endangered and Threatened Wildlife and Plants are known to occur at the site; however, three species of fish identified as Federal endangered or threatened species have been found in the Columbia River adjacent to the site. The persistent sepal yellowcress, a state-designated endangered species, is found in the riparian zone of 300-FF-1 and 300-FF-5. Two other state-designated threatened plants may exist, but have not been discovered, in the riparian zone. Several species of both plants and animals that are of concern or are under consideration for formal listing by the Federal government and Washington State are present at the site. Eleven sites of cultural significance have been identified by cultural resource surveys conducted at the 300-FF-2 Operable Unit. Most soil excavation associated with remedies at the site would occur in areas that are already extensively disturbed, so the likelihood of encountering cultural/archeological resources is low. However, if archeological resources are discovered during project activities, the procedures documented in the Hanford Cultural Resource Management Plan would be followed. 300-FF-1 Operable Unit (OU 1) The 300-FF-1 Operable Unit covers an area of approximately 47.4 ha (117 acres) and contains many of the current and past 300 Area liquid waste disposal units. The 300-FF-1 Operable Unit is bounded on the east side by the Columbia River and on the north, south, and west sides by the 300-FF-2 Operable Unit. The waste sites in 300-FF-1 are not near any wetlands and are not within the 100-year floodplain. The sites in 300-FF-1 have been divided into two categories: process waste sites and the burial ground. The process waste sites received primarily liquid wastes, and the burial ground received primarily soil wastes. Process Waste Sites The process waste sites are the South Process Pond, the North Process Pond, the Process Trenches, the Process Trenches Spoils Pile, the Process Sewers, the Sanitary Tile Field and other sanitary sewage waste sites, the Ash Pits, the Filter Backwash Pond, the Retired Filter Backwash Pond ( located over part of the South Process Pond), the North Process Pond Scraping Disposal Area, the 300-3 Aluminum Hydroxide site, and Landfills 1a, 1b, 1c, and 1d. Landfills 1a, 1c, and 1d were originally grouped with the Burial Grounds in the remedial investigation and feasibility study (RI/FS). After further evaluation, however, it was determined that the remedy for the process waste units also will apply to the landfills for the following reasons: the landfills are small in area and volume when compared to the burial ground, and Landfills 1a, and 1c are near the North Process Pond and the Columbia River. The South Process Pond is an inactive, unlined surface impoundment in the southern area of 300-FF-1. The South Process Pond was the first disposal facility for liquid process wastes in the 300 Area. These liquid wastes contained uranium, copper, and aluminum, as well as traces of other contaminants. The pond also received slurried ash from the coal-fired power house. It was built in 1943 and was operated until 1975, when it was replaced by the Process Trenches. The pond was originally a single large infiltration basin with the inlet in the southwest corner. In 1948, after the North Process Pond was constructed, the inlet was moved to the northwest corner. In 1951, a dike was constructed across the south end of the pond to form the eastern Ash Pit and the now-retired filter backwash pon d ( now called the Retired Filter Backwash Pond). Later, dikes were added to route the flow through the pond. The inlet was in the northwest corner, from which the wastewater flowed through three small settling basins on the west side of the pond into two larger infiltration basins. The pond had no outlet; water loss was by infiltration and evaporation. The pond was periodically dredged to improve infiltration and after a dike failure in 1948 resulted in a release to the Columbia River. Dredging was discontinued after 1969 when large quantities of sodium aluminate were no longer disposed to the pond. The dredge spoils were placed on the pond dikes and used elsewhere as fill. The pond was deactivated in 1975; however; the east infiltration basin continued to be used for disposal of filter backwash until 1986. The dikes separating the settling basins and the west infiltratration basin were partially removed at this time to provide cover for the pond sludges. The South Process Pond is now dry, and portions have been covered with soil. The North Process Pond was constructed in 1948 after a dike failure at the South Process Pond. The North Process Pond is in the center of 300-FF-1, approximately 91 m (300 Ft) west of the Columbia River. The North Process Pond was operated until 1975. The North Process Pond originally consisted of a single large infiltration basin. This basin was later subdivided into three small settling basins and one large infiltration basin. The original three settling basins were replaced by three new basins in 1961/1962. The original basins on the west side of the facility were then used for sludge disposal. The inlet for the pond was at the southwest corner. The pond had no outlet; water loss was by infiltration and evaporation. Lack of infiltration was also a problem for the North Process Pond. The pond was periodically dredged to improve infiltration from 1948 through 1969. Dredge spoils were spread on the dikes or spread and covered in the ad jacent North Pond Scraping Disposal Area. The North Pond Scraping Disposal Area, also known as the 618-12 Burial Ground, is immediately south of the North Process Pond. This area was used to dispose of pond sludges. The site has since been covered with coal ash and clean fill. The Process Trenches are an inactive Resource Conservation and Recovery Act (RCRA) treatment, storage and disposal (TSD) unit that will be closed pursuant to the Washington Dangerous Waste Regulations (WAC 173-303). The Hanford Site dangerous waste permit will be modified to incorporate specific permit conditions for this closure. The Process Trenches consist of two parallel, unlined trenches that operated from 1975 to 1994. The two trenches called the east and west trenches, are separated by an earthen berm. The trenches are located near the western boundary of the 300-FF-1 Operable Unit, approximately 300 m (1,000 ft) west of the Columbia River. The process trenches received wastes from the process sewer system, including the low-level radioactive waste from 307 Retention Basins. The trenches did not have outlets; water loss was by infiltration and evaporation. By the late 1980's, the process wastewater contained very little uranium. However, the groundwater still had significantly elevated uranium concentration. The relatively clean process wastewater was mobilizing uranium previously deposited in the bottom of the trenches and carrying it to the groundwater. In 1991, DOE performed an expedited response action (ERA) under CERCLA removal authority at the Process Trenches. The objective was to move contaminated soils from the south end of the Process Trenches to the dry north end, thus preventing process wastewater from passing through the contaminated soil and driving contamination to groundwater. Approximately 10,800 m3 (14,000 yd3) was moved in the trenches. The more contaminated materials were placed in a depression in the northwest corner of the west trench. The less contaminated mate rial was moved to north end of the trenches, graded, and covered with a plastic barrier and a layer of clean aggregate. The contaminated sediments were left within the boundary of the Process Trenches and are referred to as the Process Trenches Spoils Pile. In 1994, a new effluent treatment and disposal facility was started up, eliminating discharges to the Process Trenches completely. The Process Sewer System transferred liquid process wastes to the process ponds and trenches. Only those portions of the process sewer system located within the operable unit are included within the scope of 300-FF-1. The system is constructed of vitreous clay pipe and the trunk sewer diameter is 61 cm (24 in) The original process sewer serving the South Process Pond was later modified to serve the North Process Pond. The process sewers were further modified to serve the Process Trenches, as well as the 307 Retention Basins located in the 300-FF-2 Operable Unit. The portion of the process sewers serving the North and South Process Ponds was reportedly abandoned in March 1975. However, documentation of abandonment exists for only the pipe that fed the southwest corner of the South Process Pond. The as-abandoned condition has not been identified for the pipe that fed the northwest corner of the South Process Pond or for the pipe to the North Process Pond. The Sanitary Sewage Waste Sites handle sanitary sewage from the 300 Area. The sewage travels through sanitary sewers constructed of vitreous clay pipe. The sanitary sewers discharge to septic tanks. The septic tanks are periodically cleaned, and the sludge is disposed of in an adjacent sludge pit. Between 1943 and 1948, the septic tanks were connected to a tile leach field constructed of perforated clay pipe. The tile field was replaced by the Sanitary Sewage Trenches, which are still in use. The south sanitary sewage trench was evidently constructed prior to or during 1948. The north sanitary sewage trench was constructed in 195 2 across portions of the abandoned tile field. This ROD addresses only those sections of the sanitary sewer located within the 300-FF-1 Operable unit. The Sanitary Sewage Trenches will be taken out of service in the next few months when the sanitary wastes from the 300 Area will discharge to the City of Richland system. The Ash Pits received slurried fly ash, which was generated at the 300 Area powerhouse when coal was buried. Currently, the powerhouse is using No.6 fuel oil and no fly ash is being generated. The fly ash was slurried which water and discharged to two ash pits located between the South Process Pond and the 307 trenches. The area of the Ash Pits was originally part of the South Process Pond. Presumably, some contaminated soil and/or sludge from pond operations remains beneath the fly ash. The Ash pits originally consisted of a single trench; the trench was divided into the current configuration around 1960. The Ash pits often filled up, so sludge was removed and placed near the river bank or between the north and south process ponds. It is presumed that, as time progressed, ash was allowed to accumulated at the east end of the east pit, eventually to the point where the original extent was no longer apparent and only a limited portion of the ash was actually being used. The Filter backwash Pond was constructed in 1987 to receive filter backwash from the 300 Area potable water treatment tank. The backwash contains a high concentration of alum, which settles in the pond. This facility is located directly east of the Ash Pits, as currently configured. Prior to 1951, the area was part of the South Process Pond. The pond has a synthetic liner which rests on a concrete liner/foundation. After the alum has settled, the water is recycled to through the water treatment plant. The Retired Filter Backwash Pond was constructed over a portion of the infiltration basin of the South Process Pond. When the South Process Pond was retired in 1975, the infiltra tion basin was used for disposal of filter backwash. The infiltration basin operated until 1987. The 300-3 Aluminum Hydroxide Site was identified during installation of a sump pit for the 300 Area Treated Effluent Disposal Facility. The site consists of several horizontal 0.3 to 0.45 m (1 to 1.5 ft) diameter cedar logs forming a vertical wall approximately 10 ft high running in a north/south direction. The top part of the wall slopes downward to the west and the bottom part is vertical. The structure appears to be resting on a concrete slab at a depth of approximately 3 to 4.5 m ( 10 to 15 ft). A white chalky material was found during excavation. The material was determined to be Aluminum Hydroxide; Toxic Characteristic Leaching Procedure analysis indicated that the material was not a dangerous waste. The constituents in the material were all below health-based concentration and the material was determined to be non-hazardous and was left in place at the site. Landfills 1a, 1b, 1c and 1d were identified during a review of aerial photographs. Radioactive contamination and debris were found on the surface of Landfill 1a. The materials appeared to be similar to laboratory wastes. Small amounts of what appeared to be "yellowcake" (uranium oxide concentrate) were also found. Landfills 1a and 1c were identified as disturbed or graded areas north of the North Process Pond and near the Columbia River. Landfill 1d was identified as a relatively large burn pit. Historical records indicate that, although some incidental radioactive materials may have been buried in Landfill 1d, the pit was mainly for paper, wood, paint cans, and other debris. Burial Grounds A variety of solid wastes, some contaminated with uranium, were disposed in burial grounds or landfills in and around the 300 Area. One burial ground, Burial Ground 618-4, is part of 300-FF-1. The other burial grounds are in 300-FF-2. Burial Ground 618-4 is located in the northwest corner of the operable unit. It wa s used from 1955 through 1961 and is known to contain miscellaneous materials contaminated with radioactive uranium. Four archaeological sites of cultural significance and one site containing human remains have been identified within the operable unit. Consequently, any actions undertaken for remediation, or in support of remediation, will be proceeded by a field survey by cultural resource specialists. A ROD addressing 300-FF-1 (OU1) and 300-FF-5 (OU 2) was prepared in July 1996. 300-FF-5 Operabale Unit (OU 2) The 300-FF-5 Operable Unit covers an area of approximately 415 ha ( 1025 acres) and addresses the groundwater underlying 300-FF-1 and 300-FF-2. Because groundwater underlying the 300 Area discharges to the Columbia River, 300-FF-5 included an assessment of the interaction between the groundwater and the river. A ROD addressing 300-FF-1 (OU 1) and 300-FF-5 (OU 2) was completed in July 1996. 300-FF-2 Operable Unit (OU 3) The 300-FF-2 Operable Unit (OU 3) addresses radioactively- and/or chemically-contaminated soil, buried waste, and belowground structures (e.g., pipelines and concrete) at sites within the 300 Area Industrial Complex and in the general vicinity of the 300 Area Industrial Complex. Waste sites that are included in the scope of the 300-FF-2 Operable Unit were identified through a categorization process that was developed and implemented by the Tri-Parties. The categorization process resulted in identification of 56 waste sites that require remedial action under CERCLA. These sites fall into four general categories: waste sites in the 300 Area Industrial Complex (40 sites); outlying waste sites north and west of the 300 Area Industrial Complex (7 sites); general content burial grounds (7 sites); and transuranic contaminated burial grounds (2 sites). The source sites within the 300 Area Complex include trenches, storage areas, process plants, process sewers, french drains, and unplanned releases. Most 300 Area Complex sites l ie beneath existing facilities and/or paved areas and are directly impacted by current operations and/or future decontamination and decommissioning (D&D) activities. It has been estimated that approximately 150 buildings and structures need to be removed to expose the 40 soil contamination areas that need to be cleaned up pursuant to this ROD. An additional $663 million (not within the scope of this remedial action) is estimated to be required to remove materials and structures from the 300 Area to facilitate the cleanup of contaminated soil and debris. Within the complex, boundaries of contamination are not well defined, and sites often overlap each other. Implementation of 300-FF-2 remedial actions will require integration with ongoing use of the 300 Area, transition, and demolition. Several 300 Area Complex source sites involve coordination of CERCLA and RCRA regulatory authorities, and will require separate RCRA closure documents. Five sites within the 300 Area Complex consist of underground sewer systems/piping, including two active sewer systems. The five systems are comprised of more than 52 km (32 mi) of underground piping that interconnects 300 Area facilities and runs through the building interiors. Many leaks and unplanned releases associated with the sewer systems have been documented. The volume of liquids that leaked from the systems and potential future impacts to the groundwater and the Columbia River are unknown. The outlying source sites include trenches, cribs, dumping areas, storage areas, and unplanned releases. The 316-4 Crib is an outlying source site and the only 300-FF-2 source waste site that has been shown to impact groundwater. Groundwater monitoring results suggest that the uranium contamination is localized. Contaminated groundwater beneath the 316-4 Crib will be addressed as part of the 300-FF-5 Operable Unit. The general content burial grounds operated from the mid-1940s to mid-1970s to support 300 Area fuel fabrication and laboratory activities. They received a broad spectrum of chemical and radiological waste as well as solid waste and debris. The 300 Area burial grounds are difficult to characterize due to their heterogeneous nature, and quantitative characterization data are generally not available. Records documenting the inventory for many of the 300 Area burial ground sites are poor, especially for sites that operated in the 1940s and 1950s. All of the general content burial ground sites have an existing cover of soil with vegetation or asphalt. None of the general content burial grounds currently appear to be impacting groundwater. Historical records indicate that the 618-7 Burial Ground contains "hundreds" of drums of zircaloy chips from the fuel fabrication and machining processes. Zircaloy is composed of zirconium, tin, iron, chromium, and nickel. Under the right conditions, spontaneous heating can occur during the handling of finely divided zirconium scrap. Prior to burial, the chips were placed in 113.5-L (30-gal) iron drums and covered with water to mitigate their pyrophoric attribute. No records were kept to identify the exact quantity or location of the drums, and their integrity is unknown. During the plutonium production years, Hanford's 300 Area was tasked with fuels fabrication along with fuel research, testing, and examination. In 1953, the 300 Area laboratories began fuel examination and testing of irradiated fuel rods from the 100 Area production reactors. This type of laboratory analysis created highly radioactive wastes, some of which were sent to the 618-10 and 618-11 Burial Grounds for disposal in vertical pipe units and caissons. Vertical pipe units were constructed of five bottomless 55-gallon drums welded together to form a column and buried vertically. A specially designed truck and flatbed trailer equipped with casks was able to be positioned over the drum or caisson opening and waste remotely deposited into the ground. When filled, or if th e dose rate became too high, the unit was capped with concrete and work was moved to another unit. Waste packages would often break open when dropped into the vertical pipe units. Frequent surface contamination occurred from the reflux of airborne particles during waste drops. As a result, three to five large diameter caissons with offset chutes were installed at the 618-11 Burial Ground to help contain contamination and reduce exposure during disposal activities. Available records for the 618-10 and 618-11 Burial Grounds indicate that the radionuclide beta/gamma activity was generally divided into three categories for waste disposal: <10 Ci/ft3 (low-activity), 10 to 1,000 Ci/ft3 (moderate-activity), and above 1,000 Ci/ft3 (high activity). The low-activity wastes were primarily disposed in trenches, while the moderate and high-activity wastes were disposed in vertical pipe units and caissons. Some of the moderate and high-activity wastes were disposed to trenches in concrete/lead-shielded drums. The 618-10 and 618-11 Burial Grounds operated between 1954 and 1967. Both of the burial grounds have an existing cover that consists of soil with vegetation. The total quantity of plutonium or other transuranic elements within the 618-10 Burial Ground is estimated to be 1 to 2 kg (2 to 4 lb) dispersed throughout the waste site. In addition to a small amount of transuranic-contaminated waste, records indicate that the 618-10 Burial Ground trenches also contain high-activity waste and buried drums of oil. The reported quantity of plutonium or other transuranic elements in the 618-11 Burial Ground is 5 to 10 kg (11 to 22 lb) dispersed throughout the waste site. The burial ground trenches also contain high-activity waste. A tritium plume detected in January 1999 has been traced to the 618-11 Burial Ground. Investigation of the plume is ongoing. Any remedial action required will be documented in an amendment to the 300-FF-5 (OU 2) ROD. Eleven sites of cultural sign ificance have been identified by cultural resource surveys conducted at the 300-FF-2 Operable Unit. Most soil excavation associated with remedies at the site would occur in areas that are already extensively disturbed, so the likelihood of encountering cultural/archeological resources is low. However, if archeological resources are discovered during project activities, the procedures documented in the Hanford Cultural Resource Management Plan would be followed. An interim Record of Decision (ROD) was signed 4 April 2001 to address contaminated soil, debris, and solid waste at the 300-FF-2 Operable Unit (OU 3). During public review of the Proposed Plan for the 300-FF-2 OU, comments were received about the technical basis for the soil cleanup level of 350 pico curies per gram (pCi/g) for uranium. In 2001, the Tri-Parties approved the cleanup level in the ROD with a requirement that "a leach test/distribution coefficient (Kd) study will be performed prior to implementation of remedial actions to verify the soil cleanup level is protective of groundwater and river pathways." As a result, the 300 Area Uranium Leach and Adsorption Project was conducted during fiscal year (FY) 2000, FY 2001, and FY 2002. The leach study has been completed and is the basis for a change of the soil cleanup level from 350 pCi/g to 267 pCi/g based on an industrial use. An Explanation of Significant Differences (ESD) addressing the 300-FF2 OU (OU3) was completed in April 2004.

Description Text

The 300 Area began as a fuels fabrication complex in 1943. Most of the facilities in the area were involved in the fabrication of nuclear reactor fuel elements. In addition to the fuel manufacturing processes, technical support, service support, and research and development related to fuels fabrication also occurred within the 300 area. In the early 1950's, the Hanford Laboratories were constructed for research and development. As the Hanford Site production reactors were shut down, fuel fabrication in the 300 Area ceased. Research and development activities have expanded over the years. The 300 Area contains a number of support facilities, including a powerhouse for process steam production; a water intake and treatment system for potable and process water; and other facilities necessary for research and development; environmental restoration, decontamination, and decommissioning. In 1988, the Hanford Site was scored using the EPA's Hazard Ranking System. As a result of the scoring, the Hanford Site was listed on the National Priorities List (NPL) in November 1989 under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA). The Hanford site was divided and listed as four NPL Sites: the 100 Area, the 200 Area, the 300 Area, and the 1100 Area. In anticipation of the NPL listing, the U.S. Department of Energy (DOE), the U.S. Environmental Protection Agency (EPA), and the Washington State Department of Ecology (Ecology) entered into the Hanford Federal Facility Agreement and Consent Order ( known as the Tri-Party Agreement, or TPA) in May 1989. This agreement established a procedural framework and schedule for developing, implementing, and monitoring remedial response actions at Hanford. The agreement also addresses Resource Conservation and Recovery Act (RCRA) compliance and permitting. DOE, Ecology, and EPA developed a Community Relations Plan in April 1990 as part of the overall Hanford Site restoration. This plan was designed to promote public awareness of the investigation, as well as public involvement in the decision-making process. The RI/FS reports and the proposed plan for 300-FF-1 and 300-FF-5 were made available to the public in both the Administrative Record and the Information Repositories maintained at various locations. These documents were offered for a 45-day public comment period from December 4, 1995 to January 17, 1996. During that time, an extension of the comment period was requested. The public comment period was subsequently extended to February 9, 1996. A Record of Decision (ROD) was signed for the 300-FF-1 (OU 1) and 300-FF-5 (OU 2) in July 1996. An Explanation of Significant Differences (ESD) was produced in January 2000. This ESD documents a Land Disposal Restriction (LDR) variance for lead in the soil at 300-FF-1. A second Explanation of Significant Differences (ESD) was signed in June 2000. This ESD expanded the boundary of 300-FF-5 to include groundwater beneath all 300-FF-2 waste sites and burial grounds. It also required certain changes be made to the Operation and Maintenance (O&M) plan. The changes were intended to ensure that adequate institutional controls and groundwater monitoring requirements were in place at the site. An interim ROD for 300-FF-2 (OU 3) was signed April 4, 2001. This ROD addressed contaminated soil, solid waste, and debris at 56 sites within the 300 Area. The U.S. Department of Energy's Hanford Site is a 560-square mile federal facility located in southeastern Washington along the Columbia River. The region includes the incorporated cities of Richland, Pasco, and Kennewick (Tri-Cities), as well as surrounding communities in Benton, Franklin, and Grant counties. 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. The 300 Area, which encompasses approximately 1.35 sq km (0.25 sq mi), is adjacent to the Columbia River and approximately 1.6 km (1 mi) north of the Richland city limits. The Hanford Site was divided and listed as four National Priorities List (NPL) Sites: The 100 Area, the 200 Area, the 300 Area, and the 1100 Area. Each of these areas was further divided into operable units, which are groupings of individual waste units based primarily on geographic areas and common waste sources. The 300 Area NPL site consists of the following operable units: 300-FF-1, 300-FF-2 and 300-FF-5. The 300-FF-1 and 300-FF-2 Operable Units (OUs 1 and 2, respectively) address contaminated soils, structures, debris and burial grounds. The 300-FF-5 Operable Unit addresses the groundwater beneath 300-FF-1 and 300-FF-2. The Hanford Site is located in the Pasco Basin, a sediment-filled topographic and structural basin situated in the northern portion of the Columbia Plateau. Water from the Columbia river is also the source of drinking water for the 300 Area. In addition, the Columbia River is used extensively for recreation, including fishing, hunting, boating, sailboarding, water-skiing, diving, and swimming. The 300 Area is generally level, with a steep embankment dropping to the river. The unconfined aquifer beneath the 300 Area is composed of two hydrogeologically distinct formations: the Hanford and the Ringold formations. Flow in the unconfined system is generally toward the Columbia River, and groundwater even tually discharges to the river through springs and seeps in the river bottom and riverbank. The groundwater flow system has a significant impact on the contaminant distribution observed in the aquifer. Higher groundwater pore velocities, associated with the saturated Hanford formation found along the river, will quickly flush and naturally dilute contamination introduced into the aquifer and facilitate its remediation. No plants or mammals on the Federal List of Endangered and Threatened Wildlife and Plants are known to occur at the site; however, three species of fish identified as Federal endangered or threatened species have been found in the Columbia River adjacent to the site. The persistent sepal yellowcress, a state-designated endangered species, is found in the riparian zone of 300-FF-1 and 300-FF-5. Two other state-designated threatened plants may exist, but have not been discovered, in the riparian zone. Several species of both plants and animals that are of concern or are under consideration for formal listing by the Federal government and Washington State are present at the site. Eleven sites of cultural significance have been identified by cultural resource surveys conducted at the 300-FF-2 Operable Unit. Most soil excavation associated with remedies at the site would occur in areas that are already extensively disturbed, so the likelihood of encountering cultural/archeological resources is low. However, if archeological resources are discovered during project activities, the procedures documented in the Hanford Cultural Resource Management Plan would be followed. 300-FF-1 Operable Unit (OU 1) The 300-FF-1 Operable Unit covers an area of approximately 47.4 ha (117 acres) and contains many of the current and past 300 Area liquid waste disposal units. The 300-FF-1 Operable Unit is bounded on the east side by the Columbia River and on the north, south, and west sides by the 300-FF-2 Operable Unit. The waste sites in 300-FF-1 are not near any wetlands and are not within the 100-year floodplain. The sites in 300-FF-1 have been divided into two categories: process waste sites and the burial ground. The process waste sites received primarily liquid wastes, and the burial ground received primarily soil wastes. Process Waste Sites The process waste sites are the South Process Pond, the North Process Pond, the Process Trenches, the Process Trenches Spoils Pile, the Process Sewers, the Sanitary Tile Field and other sanitary sewage waste sites, the Ash Pits, the Filter Backwash Pond, the Retired Filter Backwash Pond ( located over part of the South Process Pond), the North Process Pond Scraping Disposal Area, the 300-3 Aluminum Hydroxide site, and Landfills 1a, 1b, 1c, and 1d. Landfills 1a, 1c, and 1d were originally grouped with the Burial Grounds in the remedial investigation and feasibility study (RI/FS). After further evaluation, however, it was determined that the remedy for the process waste units also will apply to the landfills for the following reasons: the landfills are small in area and volume when compared to the burial ground, and Landfills 1a, and 1c are near the North Process Pond and the Columbia River. The South Process Pond is an inactive, unlined surface impoundment in the southern area of 300-FF-1. The South Process Pond was the first disposal facility for liquid process wastes in the 300 Area. These liquid wastes contained uranium, copper, and aluminum, as well as traces of other contaminants. The pond also received slurried ash from the coal-fired power house. It was built in 1943 and was operated until 1975, when it was replaced by the Process Trenches. The pond was originally a single large infiltration basin with the inlet in the southwest corner. In 1948, after the North Process Pond was constructed, the inlet was moved to the northwest corner. In 1951, a dike was constructed across the south end of the pond to form the eastern Ash Pit and the now-retired filter backwash pon d ( now called the Retired Filter Backwash Pond). Later, dikes were added to route the flow through the pond. The inlet was in the northwest corner, from which the wastewater flowed through three small settling basins on the west side of the pond into two larger infiltration basins. The pond had no outlet; water loss was by infiltration and evaporation. The pond was periodically dredged to improve infiltration and after a dike failure in 1948 resulted in a release to the Columbia River. Dredging was discontinued after 1969 when large quantities of sodium aluminate were no longer disposed to the pond. The dredge spoils were placed on the pond dikes and used elsewhere as fill. The pond was deactivated in 1975; however; the east infiltration basin continued to be used for disposal of filter backwash until 1986. The dikes separating the settling basins and the west infiltratration basin were partially removed at this time to provide cover for the pond sludges. The South Process Pond is now dry, and portions have been covered with soil. The North Process Pond was constructed in 1948 after a dike failure at the South Process Pond. The North Process Pond is in the center of 300-FF-1, approximately 91 m (300 Ft) west of the Columbia River. The North Process Pond was operated until 1975. The North Process Pond originally consisted of a single large infiltration basin. This basin was later subdivided into three small settling basins and one large infiltration basin. The original three settling basins were replaced by three new basins in 1961/1962. The original basins on the west side of the facility were then used for sludge disposal. The inlet for the pond was at the southwest corner. The pond had no outlet; water loss was by infiltration and evaporation. Lack of infiltration was also a problem for the North Process Pond. The pond was periodically dredged to improve infiltration from 1948 through 1969. Dredge spoils were spread on the dikes or spread and covered in the ad jacent North Pond Scraping Disposal Area. The North Pond Scraping Disposal Area, also known as the 618-12 Burial Ground, is immediately south of the North Process Pond. This area was used to dispose of pond sludges. The site has since been covered with coal ash and clean fill. The Process Trenches are an inactive Resource Conservation and Recovery Act (RCRA) treatment, storage and disposal (TSD) unit that will be closed pursuant to the Washington Dangerous Waste Regulations (WAC 173-303). The Hanford Site dangerous waste permit will be modified to incorporate specific permit conditions for this closure. The Process Trenches consist of two parallel, unlined trenches that operated from 1975 to 1994. The two trenches called the east and west trenches, are separated by an earthen berm. The trenches are located near the western boundary of the 300-FF-1 Operable Unit, approximately 300 m (1,000 ft) west of the Columbia River. The process trenches received wastes from the process sewer system, including the low-level radioactive waste from 307 Retention Basins. The trenches did not have outlets; water loss was by infiltration and evaporation. By the late 1980's, the process wastewater contained very little uranium. However, the groundwater still had significantly elevated uranium concentration. The relatively clean process wastewater was mobilizing uranium previously deposited in the bottom of the trenches and carrying it to the groundwater. In 1991, DOE performed an expedited response action (ERA) under CERCLA removal authority at the Process Trenches. The objective was to move contaminated soils from the south end of the Process Trenches to the dry north end, thus preventing process wastewater from passing through the contaminated soil and driving contamination to groundwater. Approximately 10,800 m3 (14,000 yd3) was moved in the trenches. The more contaminated materials were placed in a depression in the northwest corner of the west trench. The less contaminated mate rial was moved to north end of the trenches, graded, and covered with a plastic barrier and a layer of clean aggregate. The contaminated sediments were left within the boundary of the Process Trenches and are referred to as the Process Trenches Spoils Pile. In 1994, a new effluent treatment and disposal facility was started up, eliminating discharges to the Process Trenches completely. The Process Sewer System transferred liquid process wastes to the process ponds and trenches. Only those portions of the process sewer system located within the operable unit are included within the scope of 300-FF-1. The system is constructed of vitreous clay pipe and the trunk sewer diameter is 61 cm (24 in) The original process sewer serving the South Process Pond was later modified to serve the North Process Pond. The process sewers were further modified to serve the Process Trenches, as well as the 307 Retention Basins located in the 300-FF-2 Operable Unit. The portion of the process sewers serving the North and South Process Ponds was reportedly abandoned in March 1975. However, documentation of abandonment exists for only the pipe that fed the southwest corner of the South Process Pond. The as-abandoned condition has not been identified for the pipe that fed the northwest corner of the South Process Pond or for the pipe to the North Process Pond. The Sanitary Sewage Waste Sites handle sanitary sewage from the 300 Area. The sewage travels through sanitary sewers constructed of vitreous clay pipe. The sanitary sewers discharge to septic tanks. The septic tanks are periodically cleaned, and the sludge is disposed of in an adjacent sludge pit. Between 1943 and 1948, the septic tanks were connected to a tile leach field constructed of perforated clay pipe. The tile field was replaced by the Sanitary Sewage Trenches, which are still in use. The south sanitary sewage trench was evidently constructed prior to or during 1948. The north sanitary sewage trench was constructed in 195 2 across portions of the abandoned tile field. This ROD addresses only those sections of the sanitary sewer located within the 300-FF-1 Operable unit. The Sanitary Sewage Trenches will be taken out of service in the next few months when the sanitary wastes from the 300 Area will discharge to the City of Richland system. The Ash Pits received slurried fly ash, which was generated at the 300 Area powerhouse when coal was buried. Currently, the powerhouse is using No.6 fuel oil and no fly ash is being generated. The fly ash was slurried which water and discharged to two ash pits located between the South Process Pond and the 307 trenches. The area of the Ash Pits was originally part of the South Process Pond. Presumably, some contaminated soil and/or sludge from pond operations remains beneath the fly ash. The Ash pits originally consisted of a single trench; the trench was divided into the current configuration around 1960. The Ash pits often filled up, so sludge was removed and placed near the river bank or between the north and south process ponds. It is presumed that, as time progressed, ash was allowed to accumulated at the east end of the east pit, eventually to the point where the original extent was no longer apparent and only a limited portion of the ash was actually being used. The Filter backwash Pond was constructed in 1987 to receive filter backwash from the 300 Area potable water treatment tank. The backwash contains a high concentration of alum, which settles in the pond. This facility is located directly east of the Ash Pits, as currently configured. Prior to 1951, the area was part of the South Process Pond. The pond has a synthetic liner which rests on a concrete liner/foundation. After the alum has settled, the water is recycled to through the water treatment plant. The Retired Filter Backwash Pond was constructed over a portion of the infiltration basin of the South Process Pond. When the South Process Pond was retired in 1975, the infiltra tion basin was used for disposal of filter backwash. The infiltration basin operated until 1987. The 300-3 Aluminum Hydroxide Site was identified during installation of a sump pit for the 300 Area Treated Effluent Disposal Facility. The site consists of several horizontal 0.3 to 0.45 m (1 to 1.5 ft) diameter cedar logs forming a vertical wall approximately 10 ft high running in a north/south direction. The top part of the wall slopes downward to the west and the bottom part is vertical. The structure appears to be resting on a concrete slab at a depth of approximately 3 to 4.5 m ( 10 to 15 ft). A white chalky material was found during excavation. The material was determined to be Aluminum Hydroxide; Toxic Characteristic Leaching Procedure analysis indicated that the material was not a dangerous waste. The constituents in the material were all below health-based concentration and the material was determined to be non-hazardous and was left in place at the site. Landfills 1a, 1b, 1c and 1d were identified during a review of aerial photographs. Radioactive contamination and debris were found on the surface of Landfill 1a. The materials appeared to be similar to laboratory wastes. Small amounts of what appeared to be "yellowcake" (uranium oxide concentrate) were also found. Landfills 1a and 1c were identified as disturbed or graded areas north of the North Process Pond and near the Columbia River. Landfill 1d was identified as a relatively large burn pit. Historical records indicate that, although some incidental radioactive materials may have been buried in Landfill 1d, the pit was mainly for paper, wood, paint cans, and other debris. Burial Grounds A variety of solid wastes, some contaminated with uranium, were disposed in burial grounds or landfills in and around the 300 Area. One burial ground, Burial Ground 618-4, is part of 300-FF-1. The other burial grounds are in 300-FF-2. Burial Ground 618-4 is located in the northwest corner of the operable unit. It wa s used from 1955 through 1961 and is known to contain miscellaneous materials contaminated with radioactive uranium. Four archaeological sites of cultural significance and one site containing human remains have been identified within the operable unit. Consequently, any actions undertaken for remediation, or in support of remediation, will be proceeded by a field survey by cultural resource specialists. A ROD addressing 300-FF-1 (OU1) and 300-FF-5 (OU 2) was prepared in July 1996. 300-FF-5 Operabale Unit (OU 2) The 300-FF-5 Operable Unit covers an area of approximately 415 ha ( 1025 acres) and addresses the groundwater underlying 300-FF-1 and 300-FF-2. Because groundwater underlying the 300 Area discharges to the Columbia River, 300-FF-5 included an assessment of the interaction between the groundwater and the river. A ROD addressing 300-FF-1 (OU 1) and 300-FF-5 (OU 2) was completed in July 1996. 300-FF-2 Operable Unit (OU 3) The 300-FF-2 Operable Unit (OU 3) addresses radioactively- and/or chemically-contaminated soil, buried waste, and belowground structures (e.g., pipelines and concrete) at sites within the 300 Area Industrial Complex and in the general vicinity of the 300 Area Industrial Complex. Waste sites that are included in the scope of the 300-FF-2 Operable Unit were identified through a categorization process that was developed and implemented by the Tri-Parties. The categorization process resulted in identification of 56 waste sites that require remedial action under CERCLA. These sites fall into four general categories: waste sites in the 300 Area Industrial Complex (40 sites); outlying waste sites north and west of the 300 Area Industrial Complex (7 sites); general content burial grounds (7 sites); and transuranic contaminated burial grounds (2 sites). The source sites within the 300 Area Complex include trenches, storage areas, process plants, process sewers, french drains, and unplanned releases. Most 300 Area Complex sites l ie beneath existing facilities and/or paved areas and are directly impacted by current operations and/or future decontamination and decommissioning (D&D) activities. It has been estimated that approximately 150 buildings and structures need to be removed to expose the 40 soil contamination areas that need to be cleaned up pursuant to this ROD. An additional $663 million (not within the scope of this remedial action) is estimated to be required to remove materials and structures from the 300 Area to facilitate the cleanup of contaminated soil and debris. Within the complex, boundaries of contamination are not well defined, and sites often overlap each other. Implementation of 300-FF-2 remedial actions will require integration with ongoing use of the 300 Area, transition, and demolition. Several 300 Area Complex source sites involve coordination of CERCLA and RCRA regulatory authorities, and will require separate RCRA closure documents. Five sites within the 300 Area Complex consist of underground sewer systems/piping, including two active sewer systems. The five systems are comprised of more than 52 km (32 mi) of underground piping that interconnects 300 Area facilities and runs through the building interiors. Many leaks and unplanned releases associated with the sewer systems have been documented. The volume of liquids that leaked from the systems and potential future impacts to the groundwater and the Columbia River are unknown. The outlying source sites include trenches, cribs, dumping areas, storage areas, and unplanned releases. The 316-4 Crib is an outlying source site and the only 300-FF-2 source waste site that has been shown to impact groundwater. Groundwater monitoring results suggest that the uranium contamination is localized. Contaminated groundwater beneath the 316-4 Crib will be addressed as part of the 300-FF-5 Operable Unit. The general content burial grounds operated from the mid-1940s to mid-1970s to support 300 Area fuel fabrication and laboratory activities. They received a broad spectrum of chemical and radiological waste as well as solid waste and debris. The 300 Area burial grounds are difficult to characterize due to their heterogeneous nature, and quantitative characterization data are generally not available. Records documenting the inventory for many of the 300 Area burial ground sites are poor, especially for sites that operated in the 1940s and 1950s. All of the general content burial ground sites have an existing cover of soil with vegetation or asphalt. None of the general content burial grounds currently appear to be impacting groundwater. Historical records indicate that the 618-7 Burial Ground contains "hundreds" of drums of zircaloy chips from the fuel fabrication and machining processes. Zircaloy is composed of zirconium, tin, iron, chromium, and nickel. Under the right conditions, spontaneous heating can occur during the handling of finely divided zirconium scrap. Prior to burial, the chips were placed in 113.5-L (30-gal) iron drums and covered with water to mitigate their pyrophoric attribute. No records were kept to identify the exact quantity or location of the drums, and their integrity is unknown. During the plutonium production years, Hanford's 300 Area was tasked with fuels fabrication along with fuel research, testing, and examination. In 1953, the 300 Area laboratories began fuel examination and testing of irradiated fuel rods from the 100 Area production reactors. This type of laboratory analysis created highly radioactive wastes, some of which were sent to the 618-10 and 618-11 Burial Grounds for disposal in vertical pipe units and caissons. Vertical pipe units were constructed of five bottomless 55-gallon drums welded together to form a column and buried vertically. A specially designed truck and flatbed trailer equipped with casks was able to be positioned over the drum or caisson opening and waste remotely deposited into the ground. When filled, or if th e dose rate became too high, the unit was capped with concrete and work was moved to another unit. Waste packages would often break open when dropped into the vertical pipe units. Frequent surface contamination occurred from the reflux of airborne particles during waste drops. As a result, three to five large diameter caissons with offset chutes were installed at the 618-11 Burial Ground to help contain contamination and reduce exposure during disposal activities. Available records for the 618-10 and 618-11 Burial Grounds indicate that the radionuclide beta/gamma activity was generally divided into three categories for waste disposal: <10 Ci/ft3 (low-activity), 10 to 1,000 Ci/ft3 (moderate-activity), and above 1,000 Ci/ft3 (high activity). The low-activity wastes were primarily disposed in trenches, while the moderate and high-activity wastes were disposed in vertical pipe units and caissons. Some of the moderate and high-activity wastes were disposed to trenches in concrete/lead-shielded drums. The 618-10 and 618-11 Burial Grounds operated between 1954 and 1967. Both of the burial grounds have an existing cover that consists of soil with vegetation. The total quantity of plutonium or other transuranic elements within the 618-10 Burial Ground is estimated to be 1 to 2 kg (2 to 4 lb) dispersed throughout the waste site. In addition to a small amount of transuranic-contaminated waste, records indicate that the 618-10 Burial Ground trenches also contain high-activity waste and buried drums of oil. The reported quantity of plutonium or other transuranic elements in the 618-11 Burial Ground is 5 to 10 kg (11 to 22 lb) dispersed throughout the waste site. The burial ground trenches also contain high-activity waste. A tritium plume detected in January 1999 has been traced to the 618-11 Burial Ground. Investigation of the plume is ongoing. Any remedial action required will be documented in an amendment to the 300-FF-5 (OU 2) ROD. Eleven sites of cultural sign ificance have been identified by cultural resource surveys conducted at the 300-FF-2 Operable Unit. Most soil excavation associated with remedies at the site would occur in areas that are already extensively disturbed, so the likelihood of encountering cultural/archeological resources is low. However, if archeological resources are discovered during project activities, the procedures documented in the Hanford Cultural Resource Management Plan would be followed. An interim Record of Decision (ROD) was signed 4 April 2001 to address contaminated soil, debris, and solid waste at the 300-FF-2 Operable Unit (OU 3). During public review of the Proposed Plan for the 300-FF-2 OU, comments were received about the technical basis for the soil cleanup level of 350 pico curies per gram (pCi/g) for uranium. In 2001, the Tri-Parties approved the cleanup level in the ROD with a requirement that "a leach test/distribution coefficient (Kd) study will be performed prior to implementation of remedial actions to verify the soil cleanup level is protective of groundwater and river pathways." As a result, the 300 Area Uranium Leach and Adsorption Project was conducted during fiscal year (FY) 2000, FY 2001, and FY 2002. The leach study has been completed and is the basis for a change of the soil cleanup level from 350 pCi/g to 267 pCi/g based on an industrial use. An Explanation of Significant Differences (ESD) addressing the 300-FF2 OU (OU3) was completed in April 2004.