Environmental monitoring at the Hanford Site includes near-facility environmental monitoring, surface environmental surveillance, groundwater monitoring, and vadose zone monitoring. Near-facility monitoring includes the analysis of environmental samples collected near major nuclear-related installations, waste storage and disposal units, and remediation sites. Surface environmental surveillance consists of sampling and analyzing various media on and around the site to detect potential contaminants and assess their significance to environmental and human health. Groundwater sampling is conducted to determine the distribution of radiological and chemical constituents in groundwater. Vadose monitoring is conducted to better understand and alleviate the spread of subsurface contamination.
The overall objectives of these monitoring and surveillance programs are to demonstrate compliance with applicable federal, state, and local regulations; confirm adherence to DOE environmental protection policies; and support environmental management decisions.
Liquid and airborne effluents that may contain radioactive or hazardous constituents are continually monitored when released to the environment at the Hanford Site. Facility operators perform the monitoring mainly through analyzing samples collected at points of release into the environment. Effluent monitoring data are evaluated to determine the degree of regulatory compliance for each facility and/or the entire site. The evaluations are also useful to assess the effectiveness of effluent treatment and pollution-management practices.
In 2001, only facilities in the 200 Areas discharged radioactive liquid effluents to the ground, which went to the State-Approved Land Disposal Site. Radioactive air emissions usually come from a building stack or a vent. Radioactive emission discharge points are located in the 100, 200, 300, and 400 Areas. Non-radioactive air pollutants from such things as diesel-powered electrical generating plants were monitored. In 2001, the 200 Areas tank farms produced reportable ammonia emissions.
Liquid effluents are discharged from facilities in all areas of the Hanford Site. Effluents that normally or potentially contain radionuclides include cooling water, steam condensate, process condensate, and wastewater from laboratories and chemical sewers. These wastewater streams are sampled and analyzed for total alpha and total beta levels as well as for selected radionuclides.
In 2001, only facilities in the 200 Areas discharged radioactive liquid effluents to the ground, which went to a state-permitted disposal site at Hanford. Liquid waste containing both radioactive and hazardous contaminants are stored at the 200 Areas in underground waste storage tanks or monitored interim storage facilities.
Radioactive airborne emissions from the Hanford Site to the surrounding region are a potential source of human exposure. Most of the radionuclides in effluents at the site are nearing levels indistinguishable from the low concentrations in the environment that occur naturally or originated from atmospheric nuclear-weapons testing. The environmental cleanup mission is largely responsible for the downward trend in radioactive emissions at Hanford.
The continuous monitoring of radioactive emissions involves analyzing samples collected at points of discharge to the environment, usually from a stack or vent. Samples are analyzed for gross alpha and gross beta concentrations as well as for selected radionuclides.
In the 100 Areas, radioactive airborne emissions originated from four points: the evaporation at the water-filled 100-K East and 100-K West Fuel Storage Basins, which contain irradiated nuclear fuel, the Cold Vacuum Drying Facility, the 105 KW integrated water treatment filter backwash system, and a low-level radiological laboratory.
In the 200 Areas, primary sources of radionuclide emissions were the Plutonium-Uranium Extraction Plant, Plutonium Finishing Plant,T Plant, 222-S Laboratory, underground waste storage tanks, and waste evaporators.
In 2001, 49 radioactive emission discharge points were active in the 200 Areas. In the 300 Area, primary sources of airborne radionuclide emissions were the 324 Waste Technology Engineering Laboratory, 325 Applied Chemistry Laboratory, 327 Post-Irradiation Laboratory, and 340 Vault and Tanks.
During 2001, the 600 Area had two radioactive emission points on the site.
Near-facility environmental monitoring is defined as routine monitoring near facilities that have the potential to discharge, or have discharged, stored, or disposed of radioactive or hazardous contaminants. Monitoring locations are associated with nuclear facilities such as the Plutonium Finishing Plant, Canister Storage Building, and the 100-K Fuel Storage Basins; inactive nuclear facilities such as N-Reactor and the Plutonium-Uranium Extraction Plant; and active and inactive waste storage or disposal facilities such as burial grounds, cribs, ditches, ponds, underground waste storage tanks, and trenches.
In 2001, routine monitoring for radioactivity in air near Hanford Site facilities used a network of continuously operating samplers at 76 locations. Air samplers were located primarily at or within ~500 meters (~1,500 feet) of sites and/or facilities having the potential for, or history of, environmental releases and were predominantly located in the prevailing downwind direction.
Air samples collected in 2001 from areas located at or directly adjacent to Hanford Site facilities had higher radionuclide concentrations than did those samples collected farther away. In general, radionuclide concentrations in most air samples collected near facilities in 2001 were at or near background levels.
Near-facility soil and vegetation sampling is conducted to detect the potential migration and deposition of facility effluents and emissions. In 2001, 92 soil samples and 75 vegetation samples were collected for analysis. The samples were collected on or adjacent to waste disposal sites and from locations downwind and near or within the boundaries of operating facilities and remedial action sites.
In soil samples, cobalt-60, strontium-90, cesium-137, plutonium-239/240, and uranium were detected consistently in 2001. The concentrations of these radionuclides were elevated near and within facility boundaries compared to background concentrations.
In vegetation samples, strontium-90, cobalt-60, cesium-137, plutonium-239/240, and uranium were detected consistently in 2001. Concentrations of these radionuclides were elevated near and within facility boundaries compared to concentrations measured offsite. The results demonstrate a high degree of variability.
Groundwater springs and/or shoreline seepage wells at the 100-N Springs are sampled annually to verify that the reported radionuclide releases to the Columbia River are not under-reported. The amount of radionuclides entering the Columbia River at these springs is calculated based on analyses of monthly samples collected near the shoreline.
In 2001, the levels of strontium-90 detected in samples from riverbank springs were highest in N Springs wells Y302 and Y303. None of the concentrations exceeded the DOE derived concentration guide. Tritium and gamma-emitting radionuclide concentrations were below analytical detection limits in 2001.
Investigative sampling was conducted in operations areas to monitor the presence or movement of radioactive and/or hazardous materials around areas of known or suspected contamination or to verify radiological conditions at specific project sites.
Generally, the predominant radionuclides discovered during these efforts were cesium-137, strontium-90, and plutonium-239/240 in the 100 and 200 Areas and uranium-234, -235, and -238 in the 300 Area.
Investigative samples collected in 2001 included mammals, animal feces, soils, and vegetation. In 2001, there were 20 instances of radiological contamination in investigative soil samples.
There were 31 instances of radiological contamination in investigative vegetation samples in 2001. Of the 31 instances, 27 were identified as tumbleweeds or tumbleweed fragments, one as grass, and three as rabbitbrush. None of these samples were analyzed for specific radionuclide activities.
In 2001, 10 wildlife samples were collected. The maximum radionuclide concentrations in investigative wildlife samples in 2001 were in mouse feces collected in the 200-West Area. Contaminants included strontium-89/90, cesium-137, europium-154, europium-155, plutonium-238, and plutonium-239/240. The numbers of animals found to be radioactively contaminated in 2001 were the lowest since 1994, and the range of radionuclide activities were within historical levels.
The Surface Environmental Surveillance Project measures the concentration of radionuclides and chemicals in environmental media and assesses potential effects of these materials on the environment and the public. Samples of air, surface water, sediment, soil and natural vegetation, agricultural products, fish, and wildlife are collected routinely or periodically. Ambient external radiation also is measured.
Atmospheric releases of radioactive material from the Hanford Site to the surrounding region are a potential source of human exposure. Radioactive constituents in air are monitored at a network of air sampling locations on and around the Hanford Site.
Airborne radionuclide samples were collected at 45 continuously operating samplers: 24 on the Hanford Site, 11 near the site perimeter, 8 in nearby communities, and 2 in distant communities. Nine stations were community-operated environmental surveillance stations managed and operated by local school teachers as part of an ongoing DOE-sponsored program to promote public awareness of Hanford Site environmental monitoring programs.
At all locations, particulates were filtered from the air and analyzed for radionuclides. Air was sampled and analyzed for selected airborne radionuclides at key locations. Several radionuclides released at the site also are found worldwide from two other sources: naturally occurring radionuclides and radioactive fallout from historical nuclear activities not associated with Hanford operations. The potential influence of emissions from site activities on local radionuclide concentrations was evaluated by comparing differences between concentrations measured at distant locations within the region and concentrations measured at the site perimeter.
In 2001, the annual average gross alpha air concentrations measured at Hanford were comparable to levels measured at distant community locations, indicating that onsite levels were predominantly a result of natural sources and worldwide radioactive fallout.
The average gross alpha concentrations for perimeter locations and nearby communities were higher than the onsite and distant averages. The site perimeter annual average gross beta air concentration was slightly higher than distant community concentrations; however, the difference was not statistically significant.
Annual average atmospheric tritium concentrations for 2001 at the Hanford Site were slightly higher than values reported for 1996 through 2000. More tritium was released from the 300 Area in 2001 than in 2000, accounting for the increase in averages from 2000 to 2001. The highest measured concentration was only 0.036% of the DOE derived concentration guide.
Samples of surface water and sediment on and near the Hanford Site were collected and analyzed to determine the potential impact to the public and the aquatic environment from Hanford-originated radiological and chemical contaminants. Samples of Hanford Site drinking water are collected, analyzed, and compared with established federal and state standards.
Radiological and chemical contaminants enter the Columbia River along the Hanford Reach through seepage of groundwater contaminated from past operations and permitted, direct-discharges of liquid effluents from Hanford facilities. Water samples were collected from the river and analyzed to determine compliance with water quality standards.
All radiological contaminant concentrations measured in Columbia River water in 2001 were less than DOE derived concentration guides and Washington State ambient surface-water quality criteria levels. The concentrations of tritium, iodine-129, and total uranium were significantly higher at the Richland Pumphouse than at Priest Rapids Dam, indicating a contribution along the Hanford Reach. All concentrations were similar to those observed in recent years.
Transect (multiple samples collected across the river) and near-shore sampling in 2001 revealed elevated tritium levels along the Benton County shoreline near the 100-N Area, Hanford town site, 300 Area, and Richland Pumphouse.
Total uranium concentrations were elevated along the Franklin County shoreline near the 300 Area and the Richland Pumphouse and likely resulted from groundwater seepage and water from irrigation return canals on the east shore of the river that contained naturally occurring uranium. Slightly elevated strontium-90 concentrations were detected in some water samples collected at near-shore locations at the 100-N Area.
Several metals and anions were detected in transect samples collected upstream and downstream of the site. Arsenic, antimony, cadmium, chromium, lead, nickel, thallium, and zinc were detected in most samples, with similar levels at most locations.
Nitrate, sulfate, and chloride concentrations were slightly elevated, compared to mid-river samples, along the Franklin County shoreline at the Richland Pumphouse transects and likely resulted from groundwater seepage associated with extensive irrigation north and east of the Columbia River. All metal and anion concentrations (including arsenic) in Columbia River water samples collected in 2001 were below regulatory limits and similar to those observed in the past.
In 2001, samples of Columbia River surface sediment were collected above McNary Dam (downstream of the site), from the Priest Rapids Dam pool (upstream of the site), and along the Hanford Reach (including some riverbank springs). In addition, sediment samples were collected above Ice Harbor Dam on the Snake River.
Radionuclides consistently detected in river sediment adjacent and downstream of the Hanford Site during 2001 included potassium-40, cesium-137, uranium-238, plutonium-238, and plutonium-239/240. The concentrations of all other radionuclides were below detection limits for most samples. Cesium-137 and plutonium isotopes exist in worldwide fallout, as well as in effluents from Hanford Site facilities. Uranium occurs naturally in the environment in addition to being present in Hanford Site effluents. Radionuclide concentrations reported in river sediment in 2001 were similar to those reported for previous years. No federal or state freshwater sediment criteria are available to assess the sediment quality of the Columbia River.
Water samples were collected from 10 Columbia River shoreline spring areas along the Hanford Site in 2001. The below normal flows on the Columbia River in 2001 allowed samples of water from riverbank springs to be collected in the spring and fall. All samples collected during 2001 were analyzed for gamma-emitting radionuclides, gross alpha, gross beta, and tritium. Samples from selected springs were analyzed for strontium-90, technetium-99, iodine-129, and uranium-234, -235, and -238. All samples were analyzed for metals and anions, with volatile organic compounds analyzed at selected locations. All analyses were conducted on unfiltered samples, except for metals analyses, which were conducted for both filtered and unfiltered samples.
Hanford-origin contaminants continued to be detected in water from riverbank springs entering the Columbia River along the Hanford Site during 2001. The locations and extent of contaminated discharges were consistent with recent groundwater surveys. Tritium, strontium-90, technetium-99, iodine-129, uranium-234, -235, and -238, metals, and anions (chloride, fluoride, nitrate, and sulfate) were detected in spring water. Volatile organic compounds were near or below the detection limits for most samples.
All radiologial contaminant concentrations measured in riverbank springs in 2001 were less than the DOE derived concentration guides. However, the spring near well 199-N-8T that has historically exceeded the DOE derived concentration guide for strontium-90 only had observed flow during one (1997) sampling attempt in the last 6 years; thus, an alternative spring was sampled in the 100-N Area.
Tritium concentrations in water samples collected in 2001 from riverbank springs at the Hanford town site exceeded the state ambient surface-water quality criteria level of 20,000 picocuries per liter. The maximum tritium concentration in riverbank spring water collected in 2001 at the 100-N Area was 17,000 picocuries per liter, which was 86% of the state ambient surface water criteria level. At the 300 Area, the maximum tritium level was 12,000 picocuries per liter, which was 60% of the criteria. The strontium-90 concentration in riverbank spring water was greater than the criteria level at the 100-H Area location.
Total uranium concentrations exceeded the EPA drinking water standard in the 300 Area. The gross alpha concentration exceeded the ambient surface-water quality criteria level in riverbank spring water at the 300 Area, which is consistent with the elevated uranium levels. All other radionuclide concentrations in 300 Area spring water were less than the state ambient surface-water quality criteria levels.
Gross beta concentrations in riverbank spring water at the 100-B Area, 100-H Area, Hanford town site, and 300 Area were elevated compared to other riverbank spring water locations. Several of the radionuclides show what appear to be increasing trends since 1995; however, radionuclide concentrations measured in the early 1990s were similar to the 2001 concentrations. Annual fluctuations in these values may reflect the influence of bank storage during the sampling period.
Most metal concentrations measured in water from riverbank springs located on the Hanford shoreline in 1999 through 2001 were below Washington State ambient surface-water acute toxicity levels. However, concentrations of chromium in the 100-B, 100-D, 100-F, 100-H, 100-K, 100-N, and 300 Areas spring water were above the state ambient surface water chronic toxicity levels.
Arsenic concentrations in water from riverbank spring water were well below the applicable state ambient surface-water chronic toxicity levels, but concentrations in all samples exceeded the federal limit for the protection of human health for the consumption of drinking water. Nitrate concentrations at all locations were below the EPA drinking water standard.
Sampling of sediment from riverbank springs began in 1993 at the Hanford town site and the 300 Area. Sampling of the riverbank springs in the 100-B, 100-F, and 100-K Areas began in 1995. Substrates at all other riverbank spring sampling locations consist of predominantly large cobble and are unsuitable for sample collection.
In 2001, sediment samples were collected at riverbank springs in the 100-B, 100-F, and 300 Areas. There was no sediment available for sampling at the 100-K and 100-N Area locations. In 2001, radionuclide concentrations in riverbank spring sediment were similar to those observed in river sediment.
Detectable amounts of most metals were found in all river sediment samples in 2001. Maximum and median concentrations of most metals were higher for sediment collected at Priest Rapids Dam.
The concentrations of cadmium, chromium, lead, nickel, thallium, and zinc had the largest differences between locations.
Metal concentrations in riverbank spring sediment samples in 2001 were similar to concentrations in Hanford Reach sediment samples.
Water was collected from two onsite ponds located near operational areas in 2001. Although the ponds are inaccessible to the public and, therefore, did not constitute a direct offsite environmental impact during 2001, they were accessible to migratory waterfowl and other animals, creating a potential biological pathway for the dispersion of contaminants.
With the exceptions of uranium-234 and uranium-238 in water samples from West Lake, radionuclide concentrations in onsite pond water were less than the DOE derived concentration guides. The median gross alpha and total uranium concentrations in West Lake exceeded ambient surface-water quality criteria. Concentrations of most radionuclides in water collected from onsite ponds in 2001 were similar to those observed in the past.
During 2001, water samples were collected from an irrigation canal located across the Columbia River and downstream from the Hanford Site at Riverview and from an irrigation water supply on the Benton County shoreline near the southern boundary of the site. As a result of public concerns about the potential for Hanford-associated contaminants in offsite water, sampling was conducted to document the levels of radionuclides in water used by the public for irrigation.
Water in the Riverview irrigation canal also was sampled three times in 2001 during the irrigation season. Unfiltered samples of the canal water were analyzed for gross alpha, gross beta, gamma emitters, tritium, strontium-90, and uranium-234, -235, and -238. In 2001, radionuclide concentrations measured in this canal's water were at the same levels detected in Columbia River water. All radionuclide concentrations were below the DOE derived concentration guides and state ambient surface-water quality criteria levels. The strontium-90 levels in the irrigation water during 2001 were similar to those reported for the Columbia River at Priest Rapids Dam and the Richland Pumphouse.
The water sample from the Benton County irrigation pumping station was analyzed for the same analytes as the Riverview irrigation canal water, except for tritium. All radionuclide concentrations were below both DOE derived concentration guides and state ambient surface-water quality criteria levels and were similar to Columbia River concentrations.
The quality of drinking water at the Hanford Site is monitored by routinely collecting and analyzing drinking water samples and comparing the resulting analytical data with established drinking water standards and guidelines.
In 2001, samples were collected from four locations on the site. All DOE-owned drinking water systems on the Hanford Site were in compliance with Washington State and EPA annual average radiological drinking water standards in 2001, and results were similar to those observed in recent years.
Food products, including milk, vegetables, fruits, and wine, were collected routinely in 2001 at several locations surrounding the Hanford Site. Samples of alfalfa also were collected at selected locations. Routine samples were collected primarily from locations in the prevailing downwind directions where airborne effluents or fugitive dust from the Hanford Site could be deposited. Samples were collected also in generally upwind directions and at locations somewhat distant from the site to provide information on reference radiation levels in food.
Routine food and farm product sampling determines the potential influence of Hanford Site releases in two ways:
Gamma scans (cobalt-60, cesium-137, and other radionuclides) and strontium-90 analyses were performed for nearly all products. Milk was analyzed for iodine-129 and tritium; wine also was analyzed for tritium.
Samples collected and analyzed in 2001 included milk, vegetables, fruit, wine, and alfalfa.
Strontium-90 was detected in one of three leafy vegetable samples collected for 2001. The result was similar to results seen in previous years. There were no gamma-emitting radionuclides detected in vegetable samples.
Strontium-90 and other man-made gamma-emitting radionuclides were not detected in grapes in 2001. Measurable levels of cesium-137 were reported slightly above the detection limit in samples from the Riverview area.
Iodine-129, strontium-90, and tritium were measured in milk samples. Levels of iodine-129 in milk collected at downwind locations have remained relatively stable for the last 5 years and were slightly higher than levels measured upwind in Sunnyside. Strontium-90 was detected in 2 of 12 milk samples analyzed in 2001, and the results were close to the analytical detection limit. Tritium concentrations in milk samples were believed to be influenced by the source of water used by the dairies. Tritium levels were low in all samples but were higher in the Sagemoor area compared to milk from both the Wahluke and Sunnyside areas.
Tritium levels in all red and white wines were low, with concentrations in Yakima Valley wines lower when compared to concentrations in Columbia Basin wines.
Measurable levels of cesium-137 and other manmade gamma-emitting radionuclides were not detected in alfalfa in 2001. Strontium-90 was found above the detection limit in two of four samples, but levels were consistent with those seen in past years.
Contaminants in fish and wildlife that inhabit the Columbia River and Hanford Site are monitored for several reasons. Wildlife have access to areas of the site containing radioactive or chemical contamination, and fish can be exposed to contamination entering the river along the shoreline.
Fish and some wildlife species exposed to Hanford contaminants might be harvested for food and may potentially contribute to offsite public exposure. However, the amount of radiological contamination measured in fish and wildlife samples is well below levels known to cause adverse health effects.
In addition, detection of contaminants in wildlife may indicate that wildlife are entering contaminated areas (burrowing in waste burial grounds) or that materials are moving out of contaminated areas (through blowing dust or food-chain transport). Consequently, fish and wildlife samples are collected at selected locations annually.
The amounts of radiological contamination measured in fish samples are well below levels that are known to cause adverse biological effects and contribute only a small proportion of the radiation dose to the maximally exposed individual. However, monitoring fish and other organisms for uptake and exposure to radionuclides at both nearby and distant locations continues to be important to track the extent and long-term trends of contamination in the Columbia River environment.
In 2001, five whitefish were collected from the Columbia River near the 100-N Area, and two whitefish were obtained from a reference site near Orofino, Idaho. Fillets and the eviscerated remains (carcass) of fish were analyzed for a variety radiological contaminants, and results from the nearby and distant locations were compared.
In 2001, muscle samples were analyzed for cesium-137 and other gamma-emitting radionuclides. Cesium-137 results were below the analytical detection limit in all seven whitefish muscle samples collected in 2001. These results are consistent with results from samples analyzed and reported from 1995 through 2000 and support results reported throughout the 1990s that indicate a gradual decline in cesium-137 levels in whitefish.
Strontium-90 was only found in the two whitefish carcass samples analyzed in 2001 and both were from the reference site. Levels of strontium-90 in carcass tissues collected from the 100-N to 100-D Areas in 2001 were consistent with levels observed in samples collected over the preceding 5 years.
Strontium-90 concentrations in carcass tissue would need to exceed 600 picocuries per gram wet weight to be near the current DOE dose limit.
Ten goose samples were collected from the Hanford Reach and one from the reference location near Vantage, Washington, in 2001. Radionuclide levels found in these samples were compared to levels in samples collected onsite in 1995, 1997, and 1999.
Cesium-137 was not detected in any goose muscle samples collected from the Hanford Site. The concentration in the sample obtained from the reference site in 2001 was reported to be 0.15 ± 0.02 picocuries per gram wet weight. The number of results reported at or below the analytical detection limit in 2001 was similar to the number reported for 28 goose samples collected from the Hanford Reach between 1995 and 2000. The 2001 levels were consistent with levels reported for other waterfowl collected on the Hanford Site and suggest that resident geese do not accumulate measurable amounts of cesium along the Hanford Reach of the Columbia River.
Strontium-90 concentrations found in goose bones were similar between the two areas sampled on the Hanford Site in 2001 and the reference site. Median and maximum results reported from Hanford goose samples in 2001 were higher than any reported from 1995 through 2000, but were similar to results from reference samples obtained in 1995, 1999, and 2001.
While the apparent increase in strontium-90 concentrations in Hanford Site goose samples obtained in 2001 is noteworthy, the strontium-90concentration in bone would need to exceed 60 picocuries per gram wet weight to be near the proposed DOE dose limit of 0.1 rad/day for terrestrial organisms.
Rabbits are good indicators of regional radioactive contamination because they have relatively small home ranges, occupy burrows, and can enter fenced-restricted areas. However, because of the cyclic-patterns of the populations over time, sampling rabbits can be very difficult when numbers are low.
In 2001, muscle and bone samples of cottontail rabbits were collected from near the 100-N Area. Reference samples of rabbits were collected near Boardman, Oregon, in 1990.
Cesium-137 concentrations in muscle samples from four rabbits collected were all below the analytical detection limit. These results are similar to those seen from a reference location sampled in 1990 and do not indicate elevated exposures from Hanford-derived sources.
Strontium-90 concentrations in the bones of four rabbits were all above the analytical detection limit. Three of the four sample results were reported near the analytical detection limit. Results from animals collected on the site suggest onsite exposure to low levels of strontium-90 around the 100-N and 200 Areas. Although low sample sizes are available to interpret the long-term trends, major changes in strontium-90 within rabbit bone tissues are not apparent over the past decade. Strontium-90 concentrations in bone tissues would need to exceed 60 picocuries per gram wet weight to be near the proposed DOE dose limit.
Soil surveillance provides information on long-term contamination trends and baseline environmental radionuclide concentrations at undisturbed locations.
Surveillance of perennial vegetation provides information on atmospheric deposition of radioactive materials in uncultivated areas and at onsite locations adjacent to potential sources of manmade radioactivity.
Accordingly, radionuclide concentrations in soil and perennial vegetation provide a baseline against which unplanned releases can be compared.
Soil and perennial vegetation samples have been collected on and around the Hanford Site for more than 50 years. Consequently, a large database exists that thoroughly documents onsite and offsite levels of manmade radionuclides in soil and perennial vegetation at specific locations.
Routine radiological surveillance of soil and vegetation on and around Hanford was last conducted in 1998. In 2001, 13 vegetation samples and 38 soil samples were collected.
In 2001, soil samples were collected onsite, at the Fitzner/Eberhardt Arid Lands Ecology Reserve, at the site perimeter, and at distant locations. All samples were analyzed for gamma-emitting radionuclides, strontium-90, uranium-234, -235, -238, and plutonium-238, -239/240. Selected samples were analyzed for americium-241. The 2001 results were compared to results from 1993, 1994, and 1998.
In 2001, observed mean radionuclide concentrations in onsite soil samples analyzed for plutonium isotopes, strontium-90, cesium-137, uranium-238, and americium-241 were at or below their respective averages from 1993, 1994, and 1998. This indicated that there has been no appreciable increase in radionuclide concentrations in onsite soil in the last several years. There were no increases in soil concentrations of any measured radionuclide at distant or perimeter locations.
The onsite average soil concentrations in 2001 were higher than at the site perimeter or distant locations for the radionuclides measured. This was consistent with historical data and reflected the higher onsite soil concentrations associated with years of nuclear materials production.
Maximum soil concentrations of several radionuclides at various distance classes were higher in 2001 than in previous years. Maximum concentrations of strontium-90 and uranium-238 on the site were higher in 2001 than maximums observed since 1993.
At the site perimeter, the plutonium-239/240 maximum concentration was slightly higher than in recent years. Uranium-238 maximum concentrations at perimeter and distant locations were also higher in 2001 than in the last 8 years, but the differences were not statistically significant.
Vegetation samples were collected at 13 locations on and around the Hanford Site in 2001. Samples were organized into four distinct groups: 1) onsite, 2) perimeter, 3) Columbia River shoreline, and 4) distant upwind.
Onsite vegation sampling locations were generally selected in areas around industrial development of the site. Downwind perimeter locations were Ringold, Byers Landing, Sagemoor, and Riverview.
Perennial vegetation samples consisted of the current year's growth of leaves, stems, and new branches collected from sagebrush and rabbitbrush. Shoreline vegetation samples were usually taken from a predominant species at the sampling location.
Vegetation sampling results in 2001 generally confirmed observations from past sampling efforts. Strontium-90, cesium-137, plutonium-238, and uranium-238 concentrations were all below nominal detection limits at distant and shoreline locations, as were cesium-137 and strontium-90 concentrations at perimeter locations. Uranium-238 was detected in three of four perimeter samples collected.
Concentrations of plutonium-238 and uranium-238 in onsite samples were all less than the detection limit. Cesium-137 and strontium-90 were each measured in one sample, and results were similar to those from past years.
The percentage of samples collected in 2001 with measurable plutonium-239/240 concentrations increased relative to those samples collected in 1993, 1994, and 1998. Between 1993 and 1998, >40% of the vegetation samples analyzed had detectable concentrations of plutonium-239/240.
In 2001, plutonium-239/240 was detected in all vegetation samples collected and analyzed. The 2001 average concentrations for all distance classes increased relative to the average concentration measured during the last 8 years.
External radiation also is surveyed on the Hanford Site. External radiation is defined as radiation originating from a source external to the body. External radiation consists of a natural component and a manmade component, which includes radionuclides generated for or from nuclear medicine, power, research, waste management, and consumer products containing nuclear materials (such as home smoke detectors).
Environmental radiation fields may be influenced by the presence of radionuclides deposited as worldwide fallout from atmospheric testing of nuclear weapons or those produced and released to the environment during the production or use of nuclear fuel. During any year, external radiation levels can vary from 15% to 25% at any location because of changes in soil moisture and snow cover.
In 2001, environmental external radiation exposure rates were measured by placing thermoluminescent dosimeters and pressurized ionization chambers at selected locations on and off the Hanford Site. External radiation and surface contamination surveys at specified locations were performed with portable radiation survey instruments.
Thermoluminescent dosimeters were positioned 1 meter (3.28 feet) above the ground at 29 locations on the site; 21 distant, community, and perimeter locations; and 26 locations along the Benton County shore of the Columbia River from Vernita to the mouth of the Yakima River. Ground contamination surveys were also conducted quarterly at 13 shoreline locations.
These measurements were made to estimate radiation exposure levels attributed to sources on the Hanford Site, estimate levels along the Hanford Reach shoreline, and help assess exposure to onsite personnel and offsite populations. Pressurized ionization chambers were situated at four community-operated monitoring stations. Real-time exposure rate data were displayed at each station to provide information to the public and to serve as an educational tool for the teachers who manage the stations.
The highest dose rates measured in 2001 were along the shoreline near the 100-N Area. These higher rates measured along the 100-N Area shoreline have been attributed to past waste management practices in that area (i.e., disposal of liquid wastes to trenches located near the river shoreline).
In 2001, the maximum annual shoreline dose rate was 129 millirems, which was not significantly different from the maximum measured in 2000, but was significantly lower than the 5-year maximum of 173 millirems per year. However, exposure levels of this magnitude did not significantly add to dose rates for the public or Hanford workers.
Radiological surveys were performed at selected Columbia River shoreline locations. The surveys showed that radiation levels were comparable to levels observed at the same locations in previous years. The highest dose rate was measured in winter along the 100-N shoreline.
Gamma radiation levels in air were monitored in 2001 at four community-operated air monitoring stations. These stations were located in Richland, north Franklin County, Basin City, and Toppenish.
Exposure rates measured at four offsite locations with pressurized ionization chambers were consistently between 7.4 and 8.9 microroentgens per hour near Hanford and 7.9 and 8.7 microroentgens per hour in Toppenish, a distant community location.
In 2001, samples were collected from 735 monitoring wells to determine the distribution and movement of existing radiological and chemical constituents in Hanford Site groundwater and identify and characterize potential and emerging groundwater contamination problems. Samples were analyzed for ~40 different radiological constituents and ~290 different chemical constituents.
The total area of groundwater contaminant plumes with concentrations exceeding drinking water standards was estimated to be ~208 square kilometers (80 square miles) in 2001. This area, which is a decrease of ~1% compared to 2000, occupies ~14% of the total area of the Hanford Site. Most of the contaminant plume area, represented by tritium, lies southeast of the 200-East Area extending to the Columbia River.
The most widespread contaminants are tritium, iodine-129, technetium-99, uranium, strontium-90, carbon tetrachloride, nitrate, and trichloroethene. Plumes of carbon-14, cesium-137, cobalt-60, and plutonium occur in isolated areas in the 100 and 200 Areas.
Tritium is one of the most widespreadcontaminants in groundwater across the Hanford Site and exceeded the 20,000-picocuries per liter drinking water standard in portions of the 100, 200, 400, and 600 Areas. Of these areas, tritium exceeded the 2-million-picocuries per liter DOE derived concentration guide in portions of the 200 and 600 Areas.
The highest tritium concentration measured at the Hanford Site in 2001 was 5.29 million picocuries per liter near the 618-11 burial ground, located near the Energy Northwest (the former Washington Public Power Supply System) site. Tritium levels on the site are expected to decrease because of dispersion and radioactive decay.
No groundwater samples showed iodine-129 concentrations above the 500-picocuries per liter DOE derived concentration guide in 2001. However, the iodine-129 plume at levels exceeding the drinking water standard (1 picocurie per liter) is extensive in the 200 and 600 Areas. At the Hanford Site, the highest level of iodine-129 detected in 2001 was 22.4 picocuries per liter near the T, TX, and TY tank farms in the 200-West Area.
Technetium-99, which has a half-life of 210,000 years, was found at concentrations greater than the 900-picocuries per liter drinking water standard in the 200-East and 200-West Areas. The highest level measured on the Hanford Site in 2001 was 81,500 picocuries per liter near the SX tank farm in the 200-West Area.
Total uranium has been detected at concentrations greater than the drinking water standard in portions of the 100, 200, and 300 Areas. The highest levels detected at the Hanford Site in 2001 were in the 200-West Area near U Plant, where uranium levels were 3,110 micrograms per liter and exceeded the DOE derived concentration guide.
In 2001, strontium-90 concentrations greater than the 8-picocuries per liter drinking water standard were found in one or more wells in the 100 and 200 Areas. Levels of strontium-90 exceeded the 1,000-picocuries per liter DOE derived concentration guide in the 100-K, 100-N, and 200-East Areas.
The 100-N Area had the widest distribution of strontium-90 detected at the Hanford Site during 2001. The maximum concentration detected was 12,000 picocuries per liter in the 200-East Area.
Carbon-14 concentrations occur in the 100-K Area and exceed the 2,000-picocuries per liter drinking water standard in two small plumes near the K-East and K-West Reactors. The maximum concentration in 2001 was 12,900 picocuries per liter near a former K-East Reactor waste disposal crib.
Cesium-137, which has a half-life of 30 years, was detected in three wells located near the inactive 216-B-5 injection well in the 200-East Area. The maximum cesium-137 concentration in 2001 was 1,910 picocuries per liter, which is greater than the interim drinking water standard. Cesium-137 appears to be restricted to the immediate vicinity of the former injection well.
Cobalt-60 was detected in the northwestern part of the 200-East Area. The maximum concentration measured in 2001 was 77.1 picocuries per liter at the BY cribs. This concentration was below the 100-picocuries per liter drinking water standard and the 5,000-picocuries per liter DOE derived concentration guide.
Plutonium was released to the soil column in the past at several locations in both the 200-West and 200-East Areas. The half-lives of plutonium-239 and plutonium-240 are 24,000 and 6,500 years, respectively. The only location where plutonium isotopes were detected in groundwater on the Hanford Site was near the inactive 216-B-5 injection well in the 200-East Area. Plutonium levels near the injection well have changed significantly since monitoring for plutonium began in the 1980s.
The maximum plutonium-239/240 concentration near this injection well during 2001 was 63 picocuries per liter, which exceeds the 30-picocuries per liter DOE derived concentration guide.
Summary of Pump-and-Treat Systems |
and a Soil-Vapor Extraction System
|Location||Startup Date||Contaminant||Mass Removed (Groundwater Processed) in 2001||Mass Removed (Groundwater Volume Processed) Since Startup|
Groundwater Pump-and-Treat Systems
|100-D Area||1997||Hexavalent chromium||20.5 kilograms
(96.7 million liters)
(550 million liters)
|100-H Area||1997||Hexavalent chromium||5.8 kilograms
(125.9 million liters)
(631.3 million liters)
|100-K Area||1997||Hexavalent chromium||36.2 kilograms
(338.8 million liters)
(1.24 million liters)
|100-N Area||1995||Strontium-90||0.18 curies
(114.7 million liters)
(666.5 million liters)
|1994||Carbon tetrachloride||1,177 kilograms
(326 million liters)
(1.67 billion liters)
|1994||Carbon tetrachloride||2.41 kilograms
(98.2 million liters)
(554.5 million liters)
(98.2 million liters)
(554.5 million liters)
(98.2 million liters)
(554.5 million liters)
(98.2 million liters)
(554.5 million liters)
|200-West Area||1992||Carbon tetrachloride||710 kilograms||77,170 kilograms|
Several non-radioactive chemicals regulated by EPA and Washington State also were present in Hanford Site groundwater. These were carbon tetrachloride, chloroform, chromium, cyanide, fluoride, nitrate, tetrachloroethene, cis-1,2-dichloroethene, and trichloroethene.
Of these chemicals, nitrate, chromium, and carbon tetrachloride were the most widely distributed in Hanford Site groundwater.
Nitrate is the most widespread chemical contaminant in Hanford Site groundwater because of its mobility in groundwater and the large volumes of waste containing nitrate discharged to the ground. However, the areas affected by levels greater than the drinking water standard are small.
In 2001, nitrate was measured at concentrations greater than the drinking water standard (45 milligrams per liter) in portions of the 100, 200, 300, 600, and former 1100 Areas. The maximum nitrate concentration measured on the Hanford Site in 2001 was 1,300 milligrams per liter in the 200-West Area.
Chromium was detected above the drinking water standard in 2001 at the 100-D, 100-H, 100-K, 100-N, 200-East, and 200-West Areas. The maximum detected concentration was 5,660 micrograms per liter in the 100-D Area.
In the hexavalent form, chromium is very mobile in groundwater. Groundwater pump-and-treat systems continued to operate in 2001 to reduce the amount of hexavalent chromium entering the Columbia River at the 100-D, 100-H, and 100-K Areas. The purpose of the pump-and-treat systems is to prevent discharge of hexavalent chromium into the Columbia River at concentrations exceeding 11 micrograms per liter, which is EPA's standard for protection of freshwater aquatic life.
Carbon tetrachloride contamination occurs above the 5-milligrams per liter drinking water standard in much of the 200-West Area and represents one of the most significant contaminant plumes at the Hanford Site. The plume, which covers an area of more than 11 square kilometers (4 square miles), extends past the 200-West Area boundary into the 600 Area.
Carbon tetrachloride has been found to have a high degree of mobility in groundwater. The highest concentration measured in 2001 was 7,400 micrograms per liter near the Plutonium Finishing Plant in the 200-West Area.
The highest chloroform concentrations were measured in the vicinity of the Plutonium Finishing Plant in the 200-West Area, where the maximum level was 160 micrograms per liter in early 2001. These concentrations are above the 100-micrograms per liter drinking water standard.
In 2001, trichloroethene was detected at levels greater than the 5-micrograms per liter drinking water standard in several wells in the 100, 200, and 600 Areas.
The most widespread area of contamination occurred in the 200-West Area. The highest concentration measured in 2001 was 21 micrograms per liter in a well northeast of the Plutonium Finishing Plant.
The highest levels of cyanide were detected in samples collected from wells in the northwestern part of the 200-East Area. The maximum concentration measured in 2001 was 423 micrograms per liter, which is above the 200 micrograms per liter drinking water standard.
At this time, fluoride has a primary drinking water standard of 4 micrograms per liter and a secondary standard of 2 micrograms per liter. Secondary standards are based primarily on aesthetic, rather than health, considerations. Fluoride was detected above the primary drinking water standard in two monitoring wells at the T tank farm in the 200-West Area in 2001. The maximum fluoride concentration was 4.9 micrograms per liter on the east side of T tank farm. A few other wells near T tank farm showed concentrations above the secondary standard.
The vadose zone is defined as the area between the ground surface and the water table. This subsurface zone also is referred to as the unsaturated zone or the zone of aeration. The vadose zone functions as a transport pathway or storage area for water and other materials located between the soil surface and the groundwater aquifers.
Historically, the vadose zone at industrialized and waste disposal areas at the Hanford Site has been contaminated with large amounts of radioactive and non-radioactive materials through the intentional and unintentional discharge of liquid waste to the soil column, the burial of contaminated solid waste, and the airborne contaminants deposited on the ground.
Depending on such factors as the makeup of the soil, the geology of the area, the nature of the waste, and the amount of water or other fluids available to mobilize the contaminant, contaminants can move downward and laterally through the soil column, can be chemically bound to soil particles (and immobilized), or can be contained by geologic formations.
Radioactive and hazardous waste in the soil column from past intentional liquid waste disposal, unplanned leaks, solid waste burial grounds, and underground tanks at the Hanford Site are potential sources of continuing and future vadose zone and groundwater contamination. Subsurface source characterization, vadose zone monitoring, soil-vapor monitoring, and vadose zone remediation were conducted in fiscal year 2001 to better understand the distribution and mechanisms that control the movement of subsurface contamination.
Vadose zone characterization activities at single-shell tank farms in fiscal year 2001 were concentrated at the B, BX, and BY tank farms in the 200-East Area and the S and SX tank farms in the 200-West Area.
Two new boreholes were drilled at Waste Management Area B-BX-BY through subsurface contaminant plumes. A third borehole was drilled immediately outside the tank farms to obtain uncontaminated core for comparison with the contaminated material obtained in the tank farms.
Interim measures were completed at the single-shell tank farms in 2001 to minimize the subsurface movement of contaminants by preventing surface water from encroaching onto the tank farms.
Although these efforts are not strictly characterization efforts, they are important and related because they help minimize the spread of contamination beyond existing contaminated regions. During 2001, baseline spectral gamma logging of selected wells at past-practice, liquid waste disposal facilities began. The results will be a baseline against which future monitoring results can be compared.
Vadose zone characterization activities were completed in the 100-H Area to support remediation in the reactor areas. Finally, characterization activities were completed at two burial grounds in the 600 Area, north of the city of Richland. The results of these activities provide a clearer picture of the distribution of subsurface contaminants in this area.
Vadose zone monitoring occurred at four major areas on the Hanford Site in 2001. Leachate and soil gas monitoring continued at the Environmental Restoration Disposal Facility and the Solid Waste Landfill. Also, soil gas monitoring at the carbon tetrachloride expedited-response-action site continued during fiscal year 2001.
Soil gas is monitored quarterly to determine concentrations of carbon dioxide, methane, oxygen, and several key volatile compounds. No contaminants of concern were discovered above reporting limits during the 2000/2001 sampling period.
During the year, borehole geophysical monitoring of dry wells in single-shell tank farms to detect leaks and the migration of subsurface contaminants continued.
In addition to these monitoring activities, several vadose zone monitoring instruments were installed at one borehole at Waste Management Area B-BX-BY tank farms on the Hanford Site. These instruments will provide continuous soil column monitoring in that tank farm.
Soil-vapor extraction is being used to remove carbon tetrachloride from the vadose zone in the 200-West Area. Three soil-vapor extraction systems are in use. As of September 2001, 77,169 kilograms (170,128 pounds) of carbon tetrachloride had been removed from the vadose zone since extraction operations started in 1991.
Technical studies in the vadose zone were designed to help develop new, innovative methods for cleanup and monitoring at the Hanford Site.
These studies include the demonstration and testing of several geophysical methods to monitor and characterize the soil column and use of chemical parameters to distinguish various sources of subsurface waste and subsurface moisture to understand transport processes in the vadose zone. A computer model is being developed to predict the migration of subsurface contaminants based on measured infiltration rates.
Infiltration experiments also are being conducted at a clastic dike site to determine the hydrologic properties of clastic dikes.
A 3-year study of clastic dikes and their influence on vertical movement of moisture and contaminants in the vadose zone began in fiscal year 2000 and continued in 2001.
The goal is to describe the geometric and hydrologic properties of clastic dikes and extrapolate those properties to the vadose zone beneath waste storage and disposal facilities.
Clastic dikes are common sedimentary structures in the vadose zone at the Hanford Site. The dikes are vertical to subvertical structures that are often contorted and irregular. They crosscut the normal subhorizontal sand and silt beds of the Hanford formation.
Previous investigators have proposed that the dikes may provide a preferential path for contaminated water leaking from waste tanks to move through the thick unsaturated zone to the unconfined aquifer. However, there is insufficient evidence to determine if that speculation is accurate. One goal of this study is to provide information that can be used to evaluate that speculation.
Quality assurance and quality control practices are incorporated into all aspects of the Hanford Site environmental monitoring and surveillance programs.
Comprehensive quality assurance programs are conducted to assure data quality. The programs are implemented through quality assurance plans designed to meet requirements of the American National Standards Institute/American Society of Mechanical Engineers and DOE Orders. Quality assurance plans are maintained for all activities, and auditors verify conformance.
Quality control methods include, but are not limited to, replicate sampling and analysis, analysis of field blanks and blind reference standards, participation in interlaboratory cross-check studies, and splitting samples with other laboratories. Sample collections and laboratory analyses are conducted using documented and approved procedures.
When sample results are received, they are screened for anomalous values by comparing them to recent results and historical data. Analytical laboratory performance on the submitted double-blind samples, the EPA Laboratory Intercomparison Studies Program, and the national DOE Quality Assessment Program indicated that laboratory performance in 2001 was adequate overall, was excellent in some areas, and needed improvement in others.
Quality assurance/quality control for environmental monitoring and surveillance programs include procedures and protocols to:
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Document Number: PNNL-13910-SUM
Document Date: September 2002
Posted: October 2002