The Lincoln Park site consists of a former uranium processing mill sitelocated adjacent to the unincorporated community of Lincoln Park approximately 1-1/2 miles south of Canon City. The entire site is within Fremont County. The unincorporated community of Lincoln Park has approximately 3,000 residents. The site is in the Sand Creek drainage, which runs through the Lincoln Park community to the Arkansas River.
The Cotter Corporation, an affiliate of General Atomics since 2000, began operating the uranium mill in 1958. Liquid wastes containing radionuclides and heavy metals were discharged from 1958 to 1978 into eleven tailings ponds; all but three of the tailings ponds were unlined. The ponds were replaced in 1980 with the construction of two lined impoundments. Prior to 1982, a number of Lincoln Park wells showed elevated levels of contamination. The site was placed on the National Priorities List (NPL) of Superfund sites on September 21, 1984. In 1997, Cotter Corp. applied for a license amendment to reopen the mill.
General Remediation History
In 1988, the State of Colorado and the Cotter Corporation signed a Consent Decree, and EPA signed a Memorandum of Understanding, making Cotter responsible for cleanup at the site. Most residences in Lincoln Park have been hooked up to the Canon City water supply. A groundwater interception system is in place to capture the contaminated groundwater onsite and above the dam on Sand Creek and transfer this water to evaporation impoundments onsite. In addition, a reactive barrier treatment wall was installed below the Sand Creek dam in 2000 to treat any contaminated groundwater flowing under the dam. Other cleanup work has included removal of contaminated sediments in Sand Creek.
In January 2002, the US Environmental Protection Agency (EPA) issued a Record of Decision (ROD) that stated all work necessary to remediate contaminated soils in the Lincoln Park area has been accomplished. EPA has delayed making a final determination regarding groundwater cleanup activities until Cotter Corp. completes their evaluation of whether these activities will result in meeting the drinking water standard for groundwater in all areas of the contaminated plume. Current data shows that over the past several years, cleanup activities have reduced the size of the plume by nearly half.
Posted: July 31, 2012
Overview of Lincoln Park/Cotter Activities
The recently developed draft Road Map attempts to show how legacy and ongoing projects relate to upcoming projects for the closure of the Cotter Cañon City Mill and completion of remediation. One aspect of understanding this integration effort is an evaluation of actual and potential risks associated with the site.
In general terms, sources of contamination follow pathways to reach receptors.
A conceptual site model is used to evaluate combinations of sources, pathways and receptors to determine what exposure may occur. This model then identifies the data needed to determine what problems may exist. Mitigation of the problem may be accomplished by eliminating sources, interrupting pathways, or protecting receptors.
At the Cotter/Lincoln Park site, studies were performed in the 1970’s and 1980’s to identify what problems existed or could develop. Many suspected problems were studied and immediate action was taken to address problems where human exposure to contamination was occurring. A summary of the actions taken for various areas is provided below:
Lincoln Park (Road Map Operable Unit 2)
Groundwater and sediments in Lincoln Park were contaminated with uranium, molybdenum and other materials from the mill site. Numerous studies were performed to identify problems and monitoring programs put in place. Initial mitigation projects included:
· The Soil Conservation Service (SCS) Dam was constructed in the Sand Creek gap in the ridge surrounding Cotter to prevent surface water from leaving the site.
· Properties with residential water wells in the contaminated groundwater area were connected to city water to prevent the consumption of contaminated water.
· Water use surveys were initiated to identify possible additional water wells in use.
· Contaminated sediments washed down the Sand Creek drainage prior to the construction of the SCS Dam were collected and disposed on site.
· A hydraulic barrier (clay wall) was constructed at the heel of the SCS Dam to intercept groundwater from the mill site for evaporation.
· Silt fences were placed along minor drainages to prevent migration of soils possibly contaminated by windblown materials.
Subsequent mitigation projects included:
· An attempt to flush contaminants from the area between the SCS Dam and the DeWeese-Dye Ditch, which was not successful.
· Construction of a second groundwater barrier downstream of the SCS Dam to intercept groundwater passing the hydraulic barrier and return it to the site for evaporation.
Mill Site (Road Map Operable Unit 1)
Many on-site features were contaminated including the old tailings ponds, mill facilities, ore pads, groundwater, surface water and sediments, and soils. Many studies have been conducted and are continuing, along with ongoing operating procedures and monitoring programs. Initial mitigation projects included:
· Construction of new, lined tailings impoundments and removal of the old unlined tailings ponds.
· Demolition of the old mill and construction of new milling facilities.
· Contaminated groundwater and surface water collection and evaporation.
· Realignment of surface water drainages to mitigate erosion and minimize contact with contaminated soil.
· Several projects designed to intercept and remove on-site groundwater from the old ponds area.
· Enhancement of emission and dust control throughout the mill and site.
Subsequent mitigation projects included:
· Excavation of contaminated soil from the old ponds area.
· Placement of an interim cover on the secondary impoundment and dewatering of both impoundments.
· Excavation of contaminated soil along the mill entry road.
· Demolition of the mill facility (nearly complete).
Other Areas (Road Map Operable Unit 3)
In other areas where contamination was suspected, Cotter performed studies and in some cases, remediation. Mitigation projects include:
· Excavation of contaminated soils from the train depot and various locations along the railroad track.
Off-site Exposure Concerns
Numerous assessments have been performed to evaluate health risk associated with the site. These include:
· 1991 Cancer Study (ATSDR) - Residents of Lincoln Park, particularly men, may be at moderately increased risk of lung cancer, though the estimate is imprecise.
· 1991 Human Health Risk Assessment (Phase I) (CDPHE) - Determine that Lincoln Park residents were exposed population of concern. Cancer risk from ingestion of water is dominated by risk from exposure to uranium; risk of non-cancer effects from inhalation and soils not of health concern.
· 1993 Cancer Study (CDPHE) - The overall number of cancers diagnosed in Lincoln Park during 1979-1990 was not statistically higher than would be expected.
· 1996 Phase II HHRS (CDPHE) – Updated assessment methodology and to determine risks prior to remediation (1987-88); similar results to Phase I HHRA.
· 1998 Phase III Human Health Risk Assessment (CDPHE) - To determine risks after remediation initiated (1995). Risks in groundwater are highest upgradient of the DeWeese Dye ditch and decrease further downgradient. Drinking water has been supplied to residents of the area. Air exposure risks are below levels of concern.
· 1998 Cancer Study (CDPHE) - The number of cancers diagnosed in Lincoln Park during 1979 – 1995 was not higher statistically than would be expected.
· 1999 Ecological Risk Assessment - Risks to animals and plants were low.
· 2006 Lead in Indoor Dust, Outdoor Soil and Blood of Lincoln Park Neighborhood Residents (ATSDR) -Results did not indicate the presence of unusual levels of lead in residential indoor dust samples, the soil at the homes or in the blood of the occupants.
· 2010 Draft Public Health Assessment for Lincoln Park/Cotter Uranium Mill (ATSDR) - Concluded that 1) drinking from contaminated wells presents a risk, but most residents have city water, 2) contact with soil or sediment does not present a risk, 3) eating normal amounts of locally-grown fruits and vegetables does not present a risk, and 4) air emissions do not present a risk.
On-site Exposure Concerns
Significant improvements in worker and on-site monitoring coupled with enhanced worker protection procedures, and movement of Old Pond Area tailings into the Secondary Impoundment resulted in major reductions in measured exposures to workers.
Posted: July 31, 2012
Draft Final Public Health Assessment, Lincoln Park Superfund Site and Associated Activities at the Cotter Corporation Uranium Mill, Cañon City, Fremont County, Colorado, July 2011
The Colorado Department of Public Health and Environment finds the conclusions in the Agency for Toxic Substances and Disease Registry’s Draft Final Public Health Assessment to be consistent with the five year review completed by the state and EPA in 2007 for the Superfund process. The Public Health Assessment confirms that no exposure concern exists for groundwater, soils, fruits and vegetables, and air pathways associated with the Cotter Mill. Exposure pathways to chemicals of concern associated with Cotter Mill activities have been blocked or eliminated, keeping the remedies in effect at the site protective of public health and environment
ATSDR concludes that drinking water from contaminated private wells could harm people’s health. This is a public health hazard.
All homes in areas with contamination above levels of concern have been provided with city water in the 1980’s and contaminated wells should not be required for domestic purposes. Although older evaluations suggested carcinogenicity of uranium among smokers, the U.S. EPA has withdrawn its classification for carcinogenicity for uranium. Children who drink water containing high concentrations of molybdenum could be at increased risk of adverse health effects such as gout-like symptoms. However, molybdenum is not stored at high levels in the body, so it is unlikely that children will suffer long-term health effects once the exposure is stopped. In healthy people, excess molybdenum is not associated with adverse health outcomes.
ATSDR concludes that accidentally eating or touching soil and sediment in Lincoln Park will not harm people’s health.
ATSDR concludes that there is not enough information to determine if accidentally eating or touching soils on residential properties immediately north and west of Cotter Mill will harm people’s health. This area is directly downwind of the New Jersey X Zinc/College of the Canyons lead smelter and is only minimally impacted by Cotter.
ATSDR concludes that people who eat more homegrown fruits and vegetables than is average could be at risk for harmful health effects.
The people at risk irrigate their crops with contaminated private well water and eat four
times more homegrown fruits and vegetables than the average person. Since most people
do not eat that many homegrown fruits and vegetables, their health will not be harmed.
Therefore, adverse health effects are not expected in infants, children or the above-average consumer.
ATSDR concludes that ambient air emissions of particle bound radionuclides have not resulted in exposures to the public at levels known to cause adverse health outcomes.
Radon decay product concentration off-site did not appear to be related to releases from the site. Radon and its decay products appear to be from natural background and do not represent any health threat at the reported concentrations.
Surface Water Conclusion:
No adverse health effects are expected to occur as a result of exposure to manganese or to molybdenum in surface waters.
Cotter maintains financial assurance (surety) for two aspects of the site: the license, and the Remedial Action Plan (RAP).
The Remedial Action Plan Financial Assurance discussions have culminated in an agreement finalized on January 12, 2012.
Cotter submitted the annual report for financial assurance for the license on June 30, 2011 and the Department responded on July 8, 2011. Any comments regarding the financial assurance should be directed to:
Steve Tarlton, Program Manager
Comments received regarding financial assurance:
For further information, contact the Division by email (please include "Cotter" in the subject line) or call 303-692-3373 (or toll-free at 1-888-569-1831 Ext. 3373).
Posted: July 31, 2012
Cotter Recent lawsuit History (11/09/11)
The Cotter facility was scheduled for license renewal in 2000. The Department rejected the application in 2002. Cotter continued operation under “timely renewal” provisions and submitted a revised application in September 2003. The Department issued the new license in December 2004. Cotter subsequently appealed most of the license conditions. The Department was able to resolve all but a few of the disputed license conditions through a consent order issued in September 2005. CCAT joined the appeal supporting the Department.
A hearing was held in October 2005, after which the Administrative Law Judge supported the Department’s decision. The Department Executive Director issued a final decision on January 5, 2007 denying direct disposal, including Maywood soils. Cotter filed a Complaint for Judicial Review, which was decided in District Court in the Department’s favor in November 2007.
Maywood Allotment 1
In November and December 2003 Cotter was informed that information required to approve Maywood Allotment 1 would be collected as part of license renewal. In December 2003 Cotter filed suit to force a decision prior to the license renewal. The Denver District Judge agreed with Cotter and in July 2004 the department denied receipt of Maywood Allotment 1 soils on procedural and capacity issues. Cotter appealed this denial decision in July 2004 and refiled the suit requesting that the judge force Department approval, and that damages be assessed against the Department and unspecified individuals. Hearings were held in October and November 2004. The judge ruled in March 2005 supporting the Department’s denial. In April 2005, Cotter filed an exception to the judge’s decision; starting the appeal process. In April 2005 Cotter requested that the Department rescind denial and announced their intent to add tort claim to lawsuit. In January 2007 Cotter filed the third amendment to its complaint adding violation of the commerce clause. After the Denver District Court ruled against Cotter in the license renewal case, Cotter in the Spring of 2008 dismissed all of its lawsuits against the state.
Appeal of Impoundment closure decision
The information related to interim closure of the secondary impoundment provided in response to the license condition was rejected by the Department in January 2007 and Cotter was directed to provide and implement a closure plan. Cotter administratively appealed this requirement, but rescinded their appeal in May 2009.
Posted: July 31, 2012
Groundwater Contamination in Lincoln Park
The Cotter Corporation, an affilitate of General Atomics, began operating the uranium mill in 1958. Cotter’s mill is located at the edge of the Cañon City metropolitan area adjacent to the unincorporated Lincoln Park neighborhood and encroaching Cañon City developments. Liquid wastes containing radionuclides and heavy metals were discharged from 1958 to 1978 into 11 unlined tailings ponds on the mill site. Floods in the 1960’s spread tailings contamination downstream into the Lincoln Park subdivision. Ground water was impacted by leakage from the unlined tailings ponds and flowed from the site into the groundwater beneath Lincoln Park. A number of wells in the Lincoln Park area north of the site showed elevated levels of uranium and molybdenum contamination.
As a result of this contamination, the site was placed on the National Priorities List (NPL) of Superfund sites on September 21, 1984. The on-site ponds were replaced in 1980 with the construction of two new lined impoundments. Tailings from the old ponds and contamination associated with them were disposed in the impoundments. In 1988, the US District Court Consent Decree (CD) between Cotter and the department specified natural resource damage and penalty payments by Cotter and created a Remedial Action Plan (RAP) that required contamination studies and remedial actions. Among the actions taken was to build a subsurface hydraulic barrier at the heel of the SCS dam constructed in 1971 to prevent additional flooding. In addition, properties with contaminated wells were provided connections to the Cañon City water system.
Subsequently in 2000, a Permeable Reactive Treatment Wall (PRTW) was built north of the dam to catch and treat any water bypassing the dam or hydraulic barrier. Ground water collected by the wall (‘cut off wall’) flowed through a treatment cell filled with iron filings that removed contamination from the water. It worked fine for approximately eighteen months, but got plugged with calcite, and became ineffective. Some of the iron filings were removed for testing, and the treatment cell became a sump to collect ground water from the cut off wall in 2004. The system still stops ground water flow, collecting it and pumping it back over the dam and then eventually back up to the primary impoundment. The cut off wall pumps approximately 2 gallons of water per minute.
The Cotter Mill is situated in a geologic ‘bowl’ – the Chandler Syncline - that is surrounded by a ridge of rock (Vermejo Formation) except for two gaps on the north side. The big gap is where Sand Creek flows off the Cotter property, and where uranium and molybdenum ground water contamination from historic activities flowed into the Lincoln Park subdivision. This is also where surface water flooding occurred in the 1960’s from the Cotter property. The smaller gap is where water from the golf course flowed north. All surface water and ground water on the site are collected at the SCS Dam and subsurface barriers and evaporated on-site. Therefore, onsite waters do not impact areas beyond the Chandler Syncline (the ‘bowl’).
Remedial projects removed contaminated sediments from the Lincoln Park area, and in 2002, the US Environmental Protection Agency (EPA) determined that off-site soils did not present a public health threat and issued a no further action decision for that issue. Another RAP project attempted to flush contaminants and soils directly downstream of the SCS Dam, but this project was halted. A significant amount of ongoing monitoring of Lincoln Park wells continues, and water use studies have been performed to identify any uninformed well users. Semiannually, Cotter conducts a review of well permits in the area to identify possible new users. The Colorado State Engineer’s Office has included a notice to anyone requesting a new well in this area that the department should be contacted regarding the possible contamination.
While the legacy contamination is still present (though declining), remedial measures have been effective in preventing public exposure to the Lincoln Park plume. CDPHE cancer studies in 1991, 1993 and 1998 found no increased incidents of cancer in the Lincoln Park study area. The EPA Superfund Five-Year review in 2007 found the remedy continues to be protective. The ATSDR draft public health assessment in 2010, conducted at the request of CCAT, found that Cotter contamination did not present a current threat to human health or the environment.
Monitoring of the plume is ongoing. At the request of CCAT, the Governor’s office has directed a work pause for Cotter studies and remediation activities. Numerous efforts related to remediation of the Lincoln Park plume are pending the resumption of activities. Once resumed, characterization and analysis of remedial alternatives will be continued.
Posted: July 31, 2012
Cotter was licensed as a uranium mill by the Atomic Energy Commission (precursor to the Nuclear Regulatory Commission) to provide concentrated uranium to the federal government. Plans for this facility and others include retaining the tailings on-site at mill decommissioning. In addition, contaminated structures and soils would also be deposited in the tailings impoundments at closure.
Whereas historic tailings ponds at Cotter were unlined (causing on and off site groundwater contamination), the primary and secondary impoundments constructed in 1980 are lined with synthetic and clay liners. However, they were installed prior to current regulatory requirements, and were “grandfathered” in after NRC requirements were implemented. Tailings and contaminated materials associated with these ponds were collected and placed into the new impoundments. Concerns have existed for years about potential leakage, but clear evidence is obscured by the existence of springs beneath the impoundment and its liner system. The impoundment design has been evaluated during each license renewal effort including in 1979, 1993, 1996 and 2003 - 2005. The 1995 – 1996 review relied heavily on the multi-agency, multi-disciplinary Total Quality Environmental Management effort conducted from 1993 to 1995 and the concerns regarding their construction were addressed again in the license renewal completed in 2005. Additional studies revealed that significant seepage was not occurring, but minor anomalies in monitoring results required expanded and continued monitoring. Cotter did not agree with the conclusions reached by the Department, but agreed to continue the monitoring. Current studies have concluded that if any leakage is occurring, it is insignificant.
The materials going into the impoundment are those that were prescribed for that disposal and are consistent with state regulations. The 2005 license renewal addressed an alternative for removal of the tailing to another location, but this was not selected. One of the decision criteria was the community response to the potential impact of transportation of materials for disposal to the site, which would be similar for export of the tailings from the site.
The impoundment receives and evaporates water that comes from the surface and ground water collection systems installed to eliminate discharges from the site. The remainder of the material deposited in the impoundment is in solid form. Since the addition of solids to the impoundment facilitates dewatering, and dewatering will eliminate the seepage (if it exists) there appears to be no reason to discontinue decommissioning of the impoundments. More recently the impoundment receives demolition and decommissioning materials from the plant consistent with the decommissioning plan
The approved 2005 update of the mill decommissioning and tailings reclamation plan was updated from previous reclamation plans prepared for the milling facility in 1990 and 1995. The regulations establish criteria and procedures that must be met for milling source material and disposing of byproduct material in the on-site tailings impoundments. Appendix A to Part 18 provides specific technical, ownership, and long-term surveillance criteria for operation and closure of mill and tailings disposal sites. As envisioned for the tailings impoundments since their construction, following reclamation of the Canon City milling facility a designated area of the site (including the tailings impoundments) will be transferred to the U.S Department of Energy (DOE) for long-term care and maintenance and institutional control. A separate fund was established in 1979 for the long-term care of the site by the DOE.
For more information or to ask a question, please call or email:
State Unit Leader
Warren Smith, State Community Involvement Coordinator
EPA Remediation Project Manager
EPA Community Involvement Coordinator