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Lakeview Mill Site
Lake County, Oregon
| Years of Operation |
Status of Mill
or Plant Site |
Uranium Ore
Processed
(Million Short Tons) |
Production
(Million Pounds U3O8) |
| 1958-1960 |
Decommissioned |
0.13 |
0.34 |
Mill/Plant Area
(Acres) |
Disposal Cell
Area
(Acres) |
Disposal Cell
Radioactive
Waste
Volume
(Million Cubic Yards) |
Disposal Cell
Total Radioactivity
(Ci, 226Ra) |
Disposal Cell
Average Tailings
Radioactivity
(pCi/g, 226Ra) |
UMTRA Project
Final Cost
(Million Dollars) |
| 258 |
16 |
0.94 |
42 |
112 |
33.33 |
Location: The Lakeview mill site is located about one mile northwest of the City of Lakeview in Lake County, Oregon, and immediately west of U.S. 395. It is in a broad valley north of Goose Lake.
Background: Uranium deposits were discovered in south-central Oregon in the mid 1950s within the Basin and Range geological province. The deposits appear to be remnants of what possibly were once more extensive mineralized zones in essentially flat-lying host rock strata. The deposits possibly were formed by low temperature/low pressure hydrothermal action in an intensely altered tuffaceous host rock capped by a nonporous clay layer. The host rock occurs in a thick sequence of pyroclastic rocks, volcanic sediments, and lake-bed sediments interspersed with andesitic volcanic flows of Pliocene-age. Individual ore deposits are up to 150 feet in thickness, and ore was explored to a depth of 600 feet below the surface. Shallow ore consists principally of secondary uranium minerals and the deeper ore of coffinite associated with base-metal sulfide minerals. Steeply dipping and cross-cutting normal faults have cut the ore-bearing Pliocene sequence into large blocks that are displaced and tilted. It is thought that some faults were possible channels for emplacement of the uranium mineralization.
The first uranium ore production occurred in 1955 during initial development of the White King and Lucky Lass mines, which are located about 12 miles northwest of Lakeview mill site. Other uranium deposits were subsequently discovered in the area. In November 1957, the U.S. Atomic Energy Commission (AEC) entered a contract with the Lakeview Mining Company for a uranium processing mill at Lakeview, Oregon. The contract period extended through November 1963. The mill was constructed during 1958, and the first delivery of U3O8 to the AEC occurred in January 1959. The design of the Lakeview mill was similar to that of the uranium mill at Gunnison, Colorado, but included changes in its circuitry in order to treat the Lakeview district ores that contain uranium-arsenate and molybdenum-, antimony-, and other sulfide minerals. The milling process used sulfuric acid leaching of the ore and solvent extraction with an amine solvent to treat the leach liquor that had unusually high molybdenum content. Some of the ore also contained bentonitic clay that caused excessive frothing during ore processing and lowered uranium recovery. The mill’s rated capacity was 210 tons of ore per day (TPD), though the availability of ore varied and the actual amounts of ore processed ranged from 50 to about 400 TPD. In addition to ore produced from the two company-owned mines, about 15 percent of the ore processed at Lakeview was purchased from independent mine operators. After operating for only two years, the mill was closed in November 1960 due to a lack of ore. During that period, the grade of ore fed to the mill decreased from 0.20 percent U3O8 at startup in 1959 to about 0.09 percent when the mill was closed in 1960. A total of 131,355 tons of ore averaging 0.15 percent U3O8 was treated at the mill. Uranium recovery averaged 87 percent, and the total production, 342,259 pounds U3O8, was sold to the AEC.
In 1961, Kerr-McGee Oil Industries, through its subsidiary Kermac Fuel Corporation, acquired the assets of both the Lakeview Mining Company and the Gunnison Mining Company (Gunnison, Colorado). At that time, the Lakeview mill-site property consisted of 258 acres and contained the 30 acre tailings pile, which contained about 130,000 tons of tailings material that averaged about 3.7 feet in depth. The tailings impoundment utilized a natural clay liner and was surrounded by an earthen embankment. Six evaporation ponds covered about 65 acres of the original site, and the mill and supporting structures occupied about 12 acres. Between 1960 and 1968, the property had five owners. Atlantic Richfield Company (ARCO) acquired the Lakeview mill property in 1968. Under ARCO-sponsored site decontamination work, most of the contaminated materials were incorporated into the tailings pile, which was then stabilized with an 18-24 inch thick earthen cover. The mill building and other structures, emptied of useable machinery, remained at the site. Investigations of the mill site in 1976 found localized areas of elevated radioactivity and suspected contaminated-material burial sites. No evidence was found of windblown contamination from the mill site and no off-site usage of mill tailings was found. Additional removal/relocation of contaminated soil to the tailings pile during 1977 brought the mill site into compliance with the then-current Oregon State environment regulations. In March 1978, the property was purchased for use as lumber mill site.
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UMTRA Surface Remediation: Remediation of the Lakeview mill site was begun in 1986 and completed in October 1989. The work involved excavation and relocation of mill tailings and soil contaminated with radium, thorium, and uranium and mill-building structural debris to a new disposal cell site located northwest of the city of Lakeview. Relocation of the mill tailings and other site materials was necessitated by the potential for future geothermal and seismic activity in the vicinity of the Lakeview mill site. The excavated areas formerly occupied by the tailings pile, evaporation ponds, and mill site were backfilled and graded to conform with local slopes and revegetated according to applicable U.S. Environmental Protection Agency (EPA)standards.
Disposal
Area: The Lakeview Disposal Cell (also known as
the Collins Ranch Disposal site) was constructed on a 40-acre parcel of
land acquired by the State of Oregon in 1986 under a civil action suit.
The disposal cell is located about seven miles northwest of the city of
Lakeview, Oregon. About 944,000 cubic yards of contaminated materials
were relocated to the disposal cell. This amount includes contaminated
materials recovered from the cleanup of eight vicinity properties in the
Lakeview area. After the cell was filled, an engineered cap was built
up to seal the cell and assure stabilization of the relocated materials.
The cap is a three-foot thick, multilayered, earthen and rock structure
designed to prevent the release of radon from the cell and to protect
the cell's contents from erosion by wind and water and the potential infiltration
of rainwater that might lead to contamination of nearby groundwater reservoirs.
The contaminated material is covered with a 1.5-foot thick radon barrier/infiltration
layer composed of compacted fine-grained, clayey soil. A 6-inch thick
layer of crushed, coarse stone covers the radon/infiltration layer to
facilitate drainage and to prevent erosion. Above the drainage layer,
a one-foot thick layer of crushed basalt riprap material covers the top
and side slopes of the cell. The disposal cell meets EPA standards for
longevity, radon control, and groundwater protection. The cell slopes
were covered with soil and planted with native grasses to establish a
vegetative cover.
Responsibility
for Remediation: U.S. Department of Energy, 90
percent; State of Oregon, 10 percent.
Stewardship: The
former Lakeview mill and the Lakeview Disposal Cell sites are being managed
under the DOE’s Long-Term Surveillance and Monitoring (LTSM) Program in
accordance with the approved site specific plans. For the former mill
site, the DOE will be responsible in perpetuity for groundwater monitoring
and assuring that institutional controls are maintained and enforced.
For the disposal cell site, the DOE performs annual site inspections,
maintains institutional controls, monitors the cell’s structural integrity,
and performs maintenance and corrective actions as required.
Groundwater
Program: Some 59 million cubic yards of groundwater
in the vicinity of the mill site are contaminated with materials generated
from uranium ore processing, including molybdenum, radium, and arsenic.
The contaminated plume of groundwater covers about 116 acres and affects
the shallow aquifer in the stream and lake-bed strata beneath the former
mill site. Ground water outside the contaminant plume is used for domestic,
industrial, and agricultural purposes. Regionally, the ground water is
of generally poor quality and has a naturally high mineral content resulting
from active hydrothermal processes in the area. Because the groundwater
exceeds applicable potable water standards, irrespective of the contamination
caused by mill site pollutants, the EPA approved the application of supplemental
standards (Title 40 of the Code of Federal Regulations Part 192.22). Thus,
no groundwater remediation will be required for the mill site. Surface
water adjacent to the mill site has not been degraded by site contaminants.
The DOE’s activities at the former mill site include groundwater monitoring
and assuring effectiveness of institutional controls regarding groundwater
uses. In August 2000, a groundwater protection strategy was proposed to
assure human health and protect the environment. Under cooperative agreement
between the DOE and the State of Oregon, the strategy focuses on institutional
controls for the mill site’s contaminated groundwater and implementation
of restrictions on groundwater uses. It also will provide for assistance
in upgrading the City of Lakeview’s domestic water system and long-term
monitoring of groundwater in the area. Biennial monitoring of groundwater
will continue until 2013 and afterwards once every five years in perpetuity.
At the Lakeview Disposal Cells site, the DOE conducts annual
inspections along with maintenance as required. Annual monitoring of groundwater
around the site is done to demonstrate the integrity of the cell structure
and this will be continued to 2003, after which the monitoring will be
performed at intervals of once every five-years.
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