2005 Update of the Mill Decommissioning and...

2005 UPDATE OF THE MILL DECOMMISSIONING AND TAILINGS RECLAMATION PLAN

FOR THE COTTER CORPORATION CANON CITY MILLING FACILITY

Prepared For: Cotter Corporation

7800 East Dorado Street, Suite 210 Englewood, Colorado 80111

Prepared By: MFG, Inc.

3801 Automation Way, Suite 100 Fort Collins, Colorado 80525

August 2005

Canon City Milling Facility Decommissioning and Reclamation Plan

TABLE OF CONTENTS

1.0 INTRODUCTION ...............................................................................................................1 1.1 Scope of Report........................................................................................................1 1.2 Previous Reclamation Plans.....................................................................................1 1.3 Updated Conditions .................................................................................................1

2.0 SITE CONDITIONS............................................................................................................3 2.1 Location and Land Use ............................................................................................3 2.2 Geology and Seismicity ...........................................................................................3 2.3 Climate and Hydrology............................................................................................5 2.4 Geohydrology ..........................................................................................................6

3.0 MILLING FACILITY CONDITIONS ................................................................................8 3.1 Alkaline Mill ............................................................................................................8 3.2 Acid Mill Operation.................................................................................................8 3.3 Water Management ..................................................................................................9 3.4 Conditions for Resuming Operations.....................................................................10

4.0 TAILINGS RECLAMATION CRITERIA AND ALTERNATIVES ...............................13 4.1 CDPHE Reclamation Criteria ................................................................................13 4.2 NRC Reclamation Review .....................................................................................14 4.3 Other Design Guidance..........................................................................................14 4.4 Previous Reclamation Plans...................................................................................15 4.5 Updated Reclamation Plan.....................................................................................17

5.0 TAILINGS RECLAMATION PLAN................................................................................22 5.1 Drainage and Slopes ..............................................................................................22 5.2 Cover System .........................................................................................................22 5.3 Static and Seismic Stability ...................................................................................24 5.4 Radon Emanation...................................................................................................24 5.5 Erosion Protection..................................................................................................25 5.6 Infiltration ..............................................................................................................26 5.7 Biointrusion and Other Environmental Factors .....................................................27

6.0 MILL DECOMMISSIONING...........................................................................................34 6.1 Decommissioning Objectives ................................................................................34 6.2 Decommissioning Strategy ....................................................................................34 6.3 Health and Safety Procedures ................................................................................35 6.4 Pre-Decommissioning Activities ...........................................................................36 6.5 Demolition of Above-Ground Facilities ................................................................36 6.6 Demolition of Below-Ground Facilities ................................................................37 6.7 Soils Cleanup .........................................................................................................37 6.8 Material Placement ................................................................................................37

7.0 ADDITIONAL PLANS AND PERFORMANCE MONITORING ..................................39 7.1 Additional Plans.....................................................................................................39 7.2 Performance Monitoring........................................................................................40

8.0 REFERENCES ..................................................................................................................42

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LIST OF FIGURES

Figure 2.1 Site Location Map

Figure 3.1 Milling Facility Area Layout

Figure 4.1 Cover Material Borrow Area Location Map Figure 4.2 Previously Approved Tailings Reclamation Plan

Figure 5.1 Reclaimed Tailings Impoundment Layout Figure 5.2 Cross Sections A and B Figure 5.3 Cross Sections C and D Figure 5.4 Cross Sections E and F Figure 5.5 Typical Sections Figure 5.6 Typical Details

LIST OF APPENDICES

Appendix A 1999 Tailings Investigation Appendix B Cover and Erosion Protection Material Evaluation Appendix C Erosional Stability Evaluation Appendix D Radon Emanation Modeling Appendix E Slope Stability Analyses Appendix F Cover Infiltration Analyses Appendix G NRC Review Checklist Appendix H Technical Specifications for Tailings Impoundment Reclamation Appendix I Mill Decommissioning Plan Appendix J Settlement Monitoring Plan Appendix K Tailings Dewatering Plan

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1.0 INTRODUCTION

1.1 Scope of Report

This report presents an update of the mill decommissioning and tailings reclamation plan for the

Cotter Corporation (Cotter) Canon City Milling Facility site in Fremont County, Colorado. This

plan has been updated from the two previous reclamation plans prepared for the milling facility

(in 1990 and 1995), and is consistent with information evaluated and approved by Colorado

Department of Public Health and Environment, Hazardous Materials and Waste Management

Division (CDPHE).

This report has been prepared as supporting information for renewal of Radioactive Materials

License 369-01. This plan has been modified over time through the license renewal process, and

has culminated in the mill decommissioning and tailings reclamation plan outlined in this report.

1.2 Previous Reclamation Plans

The 1990 tailings reclamation and mill decommissioning plan for the Canon City Milling

Facility was prepared for Cotter Corporation (Cotter) by Water, Waste & Land, Inc. (WWL,

1990). This plan was based on optimistic predictions of mill operation, with a cover elevation on

the Primary Impoundment at approximately 5,620 feet. This plan is described in more detail in

Section 4.4.

The 1995 tailings reclamation and mill decommissioning plan for the facility was prepared by

Earth Science Consultants, Inc. (ESCI, 1995) and included as Appendix T of Cotter’s December

1995 application for amendment of Radioactive Materials License 369-01. This plan was based

on more recent predictions of mill operation, with a cover elevation on the Primary

Impoundment at approximately 5,600 feet. This plan is described in more detail in Section 4.4.

1.3 Updated Conditions

The updated information in this report reflects the following data that have been collected, work

that has been conducted, and operational strategies that have been modified since 1996.

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1. Borrow material source evaluation and durability testing for rock to be used as riprap on regraded embankment slopes and in diversion channels for tailings impoundment reclamation (conducted in 1998 and 1999).

2. Tailings subsurface drainage and dewatering evaluation and drainage system installation in the primary impoundment (conducted in 1998 and 1999).

3. Construction of berms on the outer areas of the primary tailings impoundment for enhancement of tailings pond fluid evaporation (constructed in 1999).

4. Geotechnical and radiological characterization of tailings and interim cover materials within the primary tailings impoundment (conducted in 1999).

5. Evaluation of alternative cover designs to enhance evapotranspiration, with net infiltration equivalent to the previously approved cover design (from ESCI, 1995). This evaluation was conducted in 2004.

6. Inclusion of tailings dewatering and settlement monitoring plans (prepared in 2004).

The draft of this report was submitted to CDPHE for completeness review in June 2003.

Following CDPHE review and discussions in 2003 and 2004, additional plans and updated

information have been included in the main report and appendices. Modified sections of the

report since June 2003 and updated appendices have a more recent date in the page footer or

figure title block.



2.0 SITE CONDITIONS

2.1 Location and Land Use

The Cotter Canon City Milling Facility is located in Fremont County, approximately 2 miles

south of Canon City, and approximately 1.5 miles southwest of Lincoln Park in Section 16,

Township 19 South, Range 70 West (Figure 2.1). The site lies within the Sand Creek basin that

drains to the north into the Arkansas River. Nearby population areas are primarily north and

northeast of the milling facility, although residential development has increased to the west of

the milling facility in recent years. Cotter Corporation owns approximately 2,500 acres in the

area (Cotter, 1996).

Previous mining activities in the site area include underground coal mining from 1896 through

1934, as well as copper mining and rock quarrying. A precious-metals smelter and a zinc mill

and smelter were operated northwest of the site in the early 1900s.

Agricultural land use is primarily north of the site along the Arkansas River valley. Current

activities include farming and livestock raising, based on irrigation from surface water and

groundwater sources from the Arkansas River valley. Livestock are grazed to the east and south

of the milling facility. More detailed information about nearby population distribution and land

use is provided in Cotter (1996, 2002).

2.2 Geology and Seismicity

The milling facility is located at the upper end of the Sand Creek basin, which drains to the north

through the site area, then drains to the northeast and east through Lincoln Park to its confluence

with the Arkansas River. In the site area, the Sand Creek basin is part of the Chandler Syncline

basin, which is both a geologic and topographic basin. The Chandler Syncline basin is a

structural component of the larger Canon City Embayment physiographic unit (Cotter, 1996).

Stratigraphy. The Sand Creek basin is underlain by a sequence of Cretaceous to Tertiary

sedimentary sandstones and shales. These sedimentary rocks are mantled in the bottom of the

basin by a sequence of up to 60 feet of Pleistocene alluvial materials (primarily sand to boulder-



sized materials). These alluvial materials have been removed from the Old Pond area, from the

footprint of Primary and Secondary Impoundments, and from portions of the southeast ¼ of

Section 9, Township 19 South, Range 70 West (north of the tailings impoundments).

In the bottom of the basin, the alluvial materials are underlain by the Tertiary Poison Canyon

Formation. The Poison Canyon Formation ranges in thickness from approximately 200 to 550

feet, and consists of claystones, siltstones, and sandstones. Beneath the Poison Canyon

Formation and exposed at the margins of the basin is the late Tertiary to early Cretaceous Raton

Formation. The Raton Formation is primarily a sandstone unit that ranges in thickness from

approximately 180 to 380 feet. Beneath the Raton Formation and exposed at the margins of the

basin is the late Cretaceous Vermejo Formation. The Vermejo Formation consists of sandstones,

shales, carbonaceous shales, and coal. The Vermejo Formation contained the mined coal units

mentioned in Section 2.1.

Structure. The Chandler Syncline is the primary structure in the site area. The syncline is a

closed basin formed by compressive tectonic forces in the region. The perimeter of the basin is

marked by the contact between the Poison Canyon Formation and underlying Raton and

Vermejo Formations (CGS, 1996).

Seismicity. The site is in an area of relative low incidence of seismic activity (CGS, 1996).

Eight seismic events were recorded in the area in the twentieth century, with the largest of these

being a Richter magnitude 3.6 event recorded in 1995 near Manitou Springs (35 northeast of the

site). The closest area of larger seismic activity is along the Rio Grande Rift (60 miles west of

the site). Events of Richter magnitude 5.0 to 5.5 have been recorded along this structure. The

closest fault associated with this structure is the Sangre de Cristo Fault (35 miles west of the

site).

Based on general seismicity information, the Canon City site is within a region of low seismicity.

This region is classified as a Zone 1 area in U.S. Army Corps of Engineers (1982), with a

recommended seismic coefficient of 0.025 g (where g is the acceleration of gravity). The region

is classified as a Zone 1 area in IBCO (1991), with a recommended seismic coefficient of 0.075

g. Local seismicity (from Colorado seismicity publications reviewed in Cotter, 1996) shows that



the maximum credible earthquake is a magnitude 6.5 event occurring on the Sangre de Cristo

Fault (35 miles southwest of the site).

Recent seismic events have been measured within 35 miles of Trinidad, Colorado and Raton,

New Mexico (August 10, 2005; August 1, 2004; and March 22, 2004). These events are of

magnitude 4.5 or less, and are approximately 100 miles southeast of the site (USGS, 2005). The

most critical event for seismic analysis remains the magnitude 6.5 event along the Sangre de

Cristo Fault.

For seismic analysis of the reclaimed tailings impoundments, the maximum credible earthquake

of Richter magnitude 6.5 along the Sangre de Cristo Fault was used as the design event for long-

term conditions. Based on standard seismic attenuation relationships discussed in Appendix E,

this earthquake would produce a maximum ground acceleration at the site of 0.12 g (12 percent

of the acceleration of gravity). Based on this maximum ground acceleration, a pseudostatic

coefficient of 0.10 g was used for seismic analyses of the reclaimed tailings impoundment

(described in Appendix E).

2.3 Climate and Hydrology

The site is within a semi-arid area on the eastern slope of the Front Range and Wet Mountains, in

south-central Colorado. Annual precipitation in the area averages approximately 12 inches

(Cotter, 1996). Annual pan evaporation in the area averages approximately 60 inches, with

annual lake evaporation averaging approximately 42 inches (Linsley and others, 1975), or

approximately 3.5 times average annual precipitation.

Extreme storm events that have been used for runoff and erosion protection analyses include the

100-year and probable maximum precipitation (PMP) events. The 100-year, 6 hour event is 2.8

inches (WWL, 1990). The general area PMP producing the most runoff is the 6-hour PMP,

totaling 22.5 inches (WWL, 1990). The local (1 square mile) PMP producing the most runoff is

the 1-hour PMP, totaling 11.25 inches (ESCI, 1995). The PMP precipitation totals are based on

values for the site area documented in NOAA (1988), and used for evaluation in this updated

plan.



As mentioned in Section 2.2, the Cotter mill site is within the Sand Creek basin, which drains to

the north, then northeast through Lincoln Park, and discharges into the Arkansas River. The

Sand Creek drainage basin in the site area is shown on Figure 2.1. The primary and secondary

tailings impoundments are located near the edge of the basin near its southeast corner. In the site

area, Sand Creek and its tributaries are intermittent streams.

2.4 Geohydrology

Groundwater in the mill site area is present in the Quaternary alluvial terrace deposits and in the

underlying and surrounding sedimentary rock units. Where the alluvial terrace deposits are

present, groundwater within these materials forms the uppermost aquifer. The next aquifer with

depth is groundwater within the Poison Canyon Formation.

Groundwater flow is primarily through coarse-grained zones of these units. Groundwater flow

also takes place in the Poison Canyon Formation (and lower formations) as fracture flow (Cotter,

1996). In the mill area, there is some interconnection between the alluvial terrace materials and

the Poison Canyon Formation. The direction of groundwater flow in the mill site area is

generally north to northeast toward the SCS Dam (Figure 2.1).

The facilities for groundwater management in the Sand Creek basin of the site area are described

in Cotter (1996) and summarized in Section 3.3. These facilities are located between the Old

Ponds area and the SCS Dam (Figure 2.1). The performance of these facilities relative to

groundwater quality is reported by Cotter annually, with the most recent report being the annual

report for 2004 (Cotter, 2005).



3.0 MILLING FACILITY CONDITIONS

3.1 Alkaline Mill

Cotter Corporation started processing ores at the Canon City Milling Facility in 1958 for

recovery of uranium with an alkaline leach process. Other custom milling processes including

acid leaching for recovery of other metals were also utilized from 1958 to 1979. The mill

tailings from this process were discharged into a series of ten ponds in the Sand Creek drainage

immediately east of the mill site. This area (covering approximately 100 acres) is described as

the Old Ponds Area, and was used for alkaline tailings disposal until construction of new tailings

impoundments in 1979 (Cotter, 1996).

The alkaline mill was demolished in 1999, under Radioactive Materials License Condition 11.7

(CDPHE, 1996). Materials from alkaline mill dismantling were disposed in the west corner of

the Primary Impoundment.

3.2 Acid Mill Operation

In preparation for acid-leach mill operation in 1978, a new tailings impoundment (the Main

Impoundment) was designed with two separate cells. The two separate cells were designated as

the Primary and Secondary Impoundments for acid leach and alkaline leach tailings, and disposal

of solids from the Old Ponds area. These impoundments were constructed in 1979 and

incorporated a composite liner system, consisting of a compacted clay liner overlain by synthetic

liner (Hypalon) and a protective soil cover (Cotter, 1996; CDPHE, 1996; CGS, 1996).

The Secondary Impoundment (encompassing approximately 44 acres at maximum permitted

tailings elevation) was used for disposal of alkaline tailings excavated from the Old Ponds area

between 1981 and 1983. Beginning in 1988, collected groundwater and city water (when

necessary) was pumped into the Secondary Impoundment to submerge the alkaline tailings and

eliminate the potential for fugitive dust. The Secondary Impoundment also serves as an

evaporative area for collected groundwater and tailings solutions (Cotter, 1996; CDPHE, 1996).



The Primary Impoundment (encompassing approximately 91 acres at maximum permitted

tailings elevation) was used for disposal of approximately 1.0 million cubic yards of acid leach

process tailings from 1979 through 1987. Short-term acid mill operations took place in 1990 and

1992 (CDPHE, 1996). Processing of stockpiled ore was conducted in 1999, and test processing

of caldacite ore was conducted in 2000. The mill is currently processing ores from mines from

the western slope of Colorado, and anticipates processing of alternate feed stocks and direct

disposal of CDPHE-approved material.

3.3 Water Management

Constituents of seepage from the Old Ponds area were detected in groundwater from the Sand

Creek basin in the Lincoln Park area in the early 1960s. The newer ponds in the Old Ponds area

were lined in the early 1970s. In 1971, the flood control dam on Sand Creek downstream of the

Old Pond area (the SCS Dam) was constructed by the U.S. Soil Conservation Service to retain

excess stormwater run-off (Figure 2.1). Pumpback from Cotter-operated pumping facilities in

the Sand Creek basin was started in 1979. Tailings removal from the Old Ponds area was

conducted in 1981-1983, with material placement in the Secondary Impoundment. In 1988, the

SCS Dam was modified to include a hydraulic barrier to intercept groundwater flowing in the

alluvium beneath Sand Creek. Other components of the groundwater collection system were

constructed in 1989 and 1990. A permeable reactive treatment wall was constructed

downgradient of the SCS dam in 2000. The performance of these features based on monitoring

results is presented in Cotter (2005), as well as performance breakthrough monitoring programs

implemented by Cotter (Procedure EV-100).

A component of tailings impoundments management is demonstration of fluid containment in

the Primary and Secondary Impoundments, and collection of water from groundwater

remediation activities from the 1988 Consent Decree and Remedial Action Plan. Fluid

containment for the tailings impoundments includes the capability to reduce the gradient for flow

through the liner system by pumping from the underdrain system (constructed above the liner

system) or the secondary underdrain system (within the tailings). Fluid containment in the

Primary Impoundment is monitored by the Main Impoundment Underdrain System installed

beneath the liner system (with current monitoring results presented in Cotter, 2005).



3.4 Conditions for Resuming Operations

As outlined in CGS (1996) and CDPHE (1996), Cotter Corporation planned to modify the circuit

in the acid leach mill to process additional materials with an alkaline leach process. The

resulting conditions for operation of the milling facility are summarized below.

1. Disposal of additional tailings in the Primary Impoundment at a reduced moisture content, with the additional tailings kept separate from the ponded water in the Primary Impoundment. The intended purpose for the production of reduced moisture content tailings was to lessen the time required for consolidation at closure.

2. Reduction of the acidity of the ponded water in the Primary Impoundment with lime addition to raise the pH above 4 and decrease the geochemical mobility of uranium and molybdenum in the ponded water.

During the plan development and approval process after 1998, the volume of ore available for

milling was reduced. Due to the reduced volume of ore to be processed under this plan, Cotter

determined that construction of a tailings dewatering circuit was not feasible from final cost and

scheduling standpoints.

In 1998, Cotter Corporation evaluated alternatives for tailings water management associated with

resumption of mill operation under this reduced volume scenario. The recommended water

management and tailings disposal alternative from this evaluation consisted of disposal of

tailings from the limited uranium recovery operations as a slurry into the Primary Impoundment.

This alternative was approved by CDPHE with tailings dewatering conditions outlined below.

1. Construction of a tailings dewatering system in the Primary Impoundment prior to mill start-up and tailings discharge. The dewatering system would consist of a series of horizontal drains placed on top of the existing tailings surface and draining by gravity to a collection well located on the west side of the impoundment. The dewatering system would be located between the existing tailings and additional tailings from subsequent milling operations.

2. Construction of berms (using soils within the Primary Impoundment or Old Ponds area soils) to create ponds for enhancement of evaporation of tailings fluids within the Primary Impoundment.

3. Characterization of tailings within the Primary Impoundment for geotechnical, hydraulic, radiological properties. This data would be used for tailings



reclamation planning as well as for evaluation of the feasibility of additional tailings dewatering methods (such as wells or vertical band drains).

The three conditions listed above were completed under Cotter Corporation direction in 1999.

The horizontal drain system (the secondary drain system) was constructed by Cotter Corporation

in 1999 as a series of flexible drain pipes that were connected to a single HDPE riser pipe. After

floating the flexible pipes into place, the riser pipe and flexible pipes were submerged. Water

was pumped from inside the riser pipe in 1999 to confirm hydraulic connection of the secondary

drain system. The berms for evaporation cells were constructed in 1999 as shown in Figure 3.1,

and have been operated since then. The tailings characterization results are presented in

Appendix A of this report.



4.0 TAILINGS RECLAMATION CRITERIA AND ALTERNATIVES

4.1 CDPHE Reclamation Criteria

The regulations administered by CDPHE pertaining to the Canon City milling facility are found

in 6 CCR 1007-1, Part 18, Licensing Requirements for Uranium and Thorium Processing,

establishes criteria and procedures for regulating licenses for milling source material and

disposing of byproduct material. Appendix A to Part 18, Criteria Relating to the Operation of

Mills and the Disposition of the Tailings or Wastes from These Operations provides specific

technical, ownership, and long-term surveillance criteria for operation and closure of mill and

tailings disposal sites. Key Appendix A criteria for tailings management and reclamation

alternatives at the Canon City milling facility are outlined below.

Erosional stability. Criterion 4 outlines erosional stability guidelines. These include

minimizing upstream catchment areas (4A), providing good wind protection (4B), and a

reclamation cover “employed to reduce wind and water erosion to negligible levels” (4D).

Criterion 4C states that “Embankment and cover slopes must be relatively flat after final

stabilization to minimize erosion potential and to provide conservative factors of safety assuring

long-term stability.” Criterion 4F states that “The impoundment, where feasible, should be

designed to incorporate features, which will promote deposition.”

Groundwater protection. Criterion 5 provides groundwater protection standards. Criterion 5E

lists the considerations for tailings management: 5E(2), “mill process designs which provide the

maximum practicable recycle of solutions and conservation of water to reduce the net input of

liquid to the tailings impoundment;” 5E(3), “dewatering of tailings by process devices and/or in

situ drainage systems to lower the phreatic surface and reduce the driving head for seepage,

unless tests show tailings are not amenable to such a system,” and 5E(4), “neutralization to

promote immobilization of hazardous constituents.”

Reclamation cover. Criterion 6 addresses the reclaimed tailings impoundment cover, including

cover performance and timing of cover placement. The criterion states that: “Licensees shall

place an earthen cover (or approved alternative) over tailings or wastes at the end of milling



operations and shall close the waste disposal area in accordance with a design which provides

reasonable assurance of control of radiological hazards to (i) be effective for 1,000 years, to the

extent reasonably achievable, and, in any case, for at least 200 years, and (ii) limit releases of

radon-222 from uranium byproduct materials ... to the atmosphere so as not to exceed an average

release rate of 20 picocuries per square meter per second.”

4.2 NRC Reclamation Review

The long-term requirements in Criterion 6 are consistent with the performance criteria in

Appendix A of 10 CFR 40. These include siting and design to withstand the maximum credible

earthquake. The U.S. Nuclear Regulatory Commission (NRC) has interpreted these criteria to

require designs for water erosion protection for storms up to and including the probable

maximum precipitation event (Johnson, 2002).

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. Prior to transfer, the site closure and

reclamation is reviewed by the NRC for compliance with applicable design criteria and guidance

(specifically Appendix A or 10 CFR 40). The guidelines for reclamation review of a Title II

facility are presented in NUREG-1620 (NRC, 2003). Appendix G of this report presents an

outline of where the specific review items in NRC (2003) are addressed in this report.

4.3 Other Design Guidance

Discussions of the reclamation plan with CDPHE personnel in 2003 and 2004 have included

EPA guidelines for reclamation of hazardous and municipal wastes. Guidelines for these

facilities (administered under RCRA Subtitle C and D as well as CERCLA) are outlined in ITRC

(2003) and the draft 2003 EPA technical guidance document for landfill covers. These

guidelines differ from the CDPHE and NRC performance criteria in two areas outlined below.

Design period. The period for reclamation performance under CDPHE and NRC criteria is 200

to 1,000 years. Performance also includes minimum reliance on active maintenance (Part 18

Appendix A Criterion 6 [7]). This dictates the design events to be used (probable maximum



precipitation and maximum credible earthquake events) and the emphasis on erosional stability

under extreme event or long-term conditions. The period of reclamation performance under

RCRA guidelines is a minimum of 30 years, but also includes minimum maintenance (ITRC,

2003).

Waste characteristics. The CDPHE and NRC performance criteria are based on uranium mill

tailings (sand to silt-sized material with above-background radioactivity). Consolidation and

settlement characteristics of these materials are similar to those of natural sand and silt-sized

materials. NRC guidelines for cover construction require justification of a sufficient degree of

tailings consolidation prior to cover construction (to minimize settlement of the cover). This

consolidation timing also allows covers to be constructed on relatively flat slopes, but provide

proper surface drainage after reclamation.

RCRA guidelines are based on hazardous or municipal solid waste, with cover slopes of 3 to 5

percent (ITRC, 2003). These slopes are based on providing proper surface drainage after cover

construction, to accommodate settlement of the underlying solid waste materials that continue to

weather, degrade, and generate leachate. RCRA guidelines are based on eliminating (to the

extent necessary) escape of hazardous constituents or leachate.

The design period and waste characteristics of uranium mill tailings (reflected in the CDPHE and

NRC performance criteria) and solid wastes (reflected in RCRA guidelines) result in similar

concepts for cover construction and performance, such as minimizing infiltration and

establishment of vegetation. These characteristics also result in differences between the CDPHE

and NRC performance criteria and RCRA guidelines, including cover slope requirements,

erosional stability requirements, and design features (such as biointrusion barriers). In the

reclamation plan for the tailings impoundments described in this report, the pertinent

requirements in the CDPHE and NRC performance criteria are used as the applicable guidance.

4.4 Previous Reclamation Plans

The tailings reclamation plan prepared by Water, Waste & Land, Inc. (WWL, 1990) and the

previously approved plan prepared by Earth Science Consultants, Inc. (ESCI, 1995) were based



on the criteria outlined above and administered by CDPHE. The ESCI (1995) reclamation plan

for the tailings impoundments is similar to that outlined in WWL (1990), with the following key

elements that are consistent among the plans.

1. The top surfaces of the impoundments gently sloping, with a vegetated surface.

2. The embankment surfaces regraded to slopes of 5:1 (horizontal:vertical) or less steep and covered with riprap.

3. Diversion channel surfaces armored with riprap where necessary.

4. A multi-layer cover system constructed over the tailings, with cover materials to be obtained from the Old Ponds Area and northwest borrow areas.

These plans are summarized below.

WWL (1990) plan. The first update of the tailings reclamation plan was documented in WWL

(1990). This plan was based on optimistic mill operation projections, with a final tailings

elevation of 5,617 feet in the Primary Impoundment and 5,640 feet in the Secondary

Impoundment. The drainage plan for the Secondary Impoundment included a diversion channel

for collection of upstream catchment runoff on its southwest side that drained to the northwest.

The top surface of the Secondary Impoundment was sloped to drain to the northwest into an

outlet channel separate from the diversion channel.

The final tailings elevation in the Primary Impoundment was sufficiently high that the top

surface of the impoundment was sloped to drain to the east over the Sand Creek catchment

boundary and into the Plum Creek drainage. A diversion channel on the southeast side of the

Primary Impoundment was located to convey flow to the east side of the impoundment and into

the outlet channel to the Plum Creek Drainage. Under this plan, the cover system over the

tailings consisted of a layered system 4.5 feet thick. The cover elements are outlined below

(from top to bottom).

1. Topsoil layer (0.5 feet thick) to provide a plant growth zone.

2. Northwest borrow area soil layer (1.0 foot thick) consisting of sandy clay.

3. Old Pond borrow area sand layer (2.0 feet thick).



4. Old Pond borrow area clay layer (1.0 foot thick), with a saturated hydraulic conductivity of less than 10-7 centimeters per second (0.1 feet per year).

5. Random fill (varying thickness), not part of the actual cover system, but forming a base and separation zone for cover system construction.

The planned cover material borrow area locations are shown in Figure 4.1. Riprap was planned

for erosion protection on the regraded embankment slopes on the Primary and Secondary

Impoundments, as well as in the diversion and drainage channels.

ESCI (1995) plan. The second update of the tailings reclamation plan was documented in ESCI

(1995). This previously approved plan was based on a final tailings elevation of 5,598 feet in the

Primary Impoundment and 5,645 feet in the Secondary Impoundment. The plan layout is shown

in Figure 4.2. The drainage plan for the Secondary Impoundment includes a diversion channel

on its southwest side that drained to the northwest (similar to the diversion channel in WWL,

1990). The top of the Secondary Impoundment had a domed configuration, with drainage

outward from the center of the impoundment. The southwestern portion of the Secondary

Impoundment drained into the diversion channel.

The final tailings elevation of the Primary Impoundment did not allow drainage from the top surface

of the impoundment to flow to the east into the Plum Creek drainage. A diversion channel was

located along the entire southeast side of the impoundment to convey flow to the north of the

impoundment.

The cover system over the tailings consisted of the same 4.5-foot thick layered system as in WWL

(1990) and outlined above. Cover slopes on both the Primary and Secondary Impoundments were

0.5 percent on top surfaces and 5:1 (20 percent) on regraded embankment surfaces. Riprap was

planned for erosion protection on the regraded embankment surfaces on the Primary and Secondary

Impoundments, as well as in the diversion and drainage channels.

4.5 Updated Reclamation Plan

The updated tailings reclamation plan presented in this report is based on the same final permitted

tailings elevations used in ESCI (1995). The diversion channels are in a similar location and



drainage direction as those presented in ESCI (1995): (1) on the east side of the Primary

Impoundment, and (2) on the southwest side of the Secondary Impoundment. The proposed cover

material borrow areas are the same as those presented in WWL (1990) and ESCI (1995), as shown

on Figure 4.1. The updated reclamation plan differs from the previously approved plan in ESCI

(1995) in the three areas outlined below.

Sloping of cover surface. The cover surfaces of the Primary and Secondary Impoundment are not

domed, but sloped at a constant grade to drain from the embankments to the diversion channels.

This sloping limits runoff flowing over the reclaimed embankment slope to that from precipitation

falling on the embankment slope itself. This sloping provides better control of runoff and long-term

erosion protection. Areas of runoff concentration and higher-velocity flow (in the diversion

channels and over reclaimed embankment slopes) are on natural ground or on existing earth

embankments.

The cover surface on the top of the Primary Impoundment can accommodate a uniform slope

ranging from 0.5 to 1.3 percent without requiring rock protection. This variation in slope provides

additional capacity for reclamation materials (mill debris, contaminated soils, and other materials) if

necessary.

Cover system. The cover system originally proposed for updated plan was the same multi-layered

system presented in WWL (1990) and ESCI (1995). In discussions with CDPHE in 2004 and 2005,

an alternative cover system was evaluated, consisting of a uniform subsoil zone designed to enhance

evapotranspiration. Infiltration analyses conducted in 2004 showed that the alternative, uniform

cover exhibited a similar measure of infiltration control as the multilayered cover system (for cover

systems with the same total thickness). The results of these infiltration analyses are presented in

Appendix F of this report.

From the standpoint of available construction materials, acceptable radon emanation, and control of

infiltration, the multilayered cover system and the alternative, uniform cover system both provide

acceptable performance. In the technical specifications for reclamation (Appendix H of this report),

both cover systems are included.



The details of the updated tailings reclamation plan are outlined in Section 5.0.



5.0 TAILINGS RECLAMATION PLAN

The updated tailings reclamation is presented below, with supporting technical evaluations in

specific appendices to this report, and the plan description structured to be consistent with NRC

review guidelines (NRC, 2003). The layout and details of the updated plan are shown in Figures

5.1 through 5.7.

5.1 Drainage and Slopes

The slopes and drainage for the updated reclamation plan are similar to previous plans, providing

acceptable erosional stability under long-term conditions. This includes storms up to the

Probable Maximum Precipitation (PMP) event. The evaluation of acceptable erosional stability

was conducted according to current NRC guidelines documented in NRC (1990) and Johnson

(1999, 2003), with the analysis methods and results presented in Appendix C.

As mentioned above, the drainage on the top surface of the Primary and Secondary

Impoundments has been revised to slope from the crest of the reclaimed embankment to the

diversion channels. This revision in slope provides the advantages outlined below.

1. Runoff from the cover surface does not flow over the reclaimed embankment slope. This reduces the potential for gully formation on the embankment slopes. The required erosion protection on the 5:1 reclaimed slope is based on runoff from precipitation falling on the embankment slope only.

2. Runoff from the cover surface is directed to the diversion channels located along the contact with the natural hillside. The critical areas for erosional stability are therefore the diversion channels, but are located on natural ground (and not over reclaimed materials). The channels will be provided with erosion protection as needed.

A transition is shown (Figure 5.1) between the Primary and Secondary impoundments. This

transition slope will be graded to 5:1 protected with riprap for erosion protection.

5.2 Cover System

The multilayered cover system in this updated reclamation plan is the same as that presented in

previous reclamation plans (WWL, 1990 and ESCI, 1995), as outlined below.



1. Topsoil layer (0.5 feet thick) to provide the seedbed and upper portion of a plant growth zone.

2. Sandy clay layer (1.0 feet thick) of soils from the Northwest Borrow area, to provide a subsoil layer for vegetation.

3. Sand layer (2.0 feet thick) of soils from the Old Ponds borrow area, to provide a lateral drainage layer and protective layer for the underlying clay layer.

4. Clay layer (1.0 feet thick) of soils from the Old Ponds borrow area to provide an infiltration barrier, with a saturated hydraulic conductivity of less than 10-7 cm/sec (0.1 ft/year)

5. Random fill zone (with a minimum thickness of 1.5 feet when directly above tailings) of soils from the Old Ponds area to provide a zone of separation between tailings or mill materials and the remaining cover system, as well as to provide a firm base for compaction of the clay layer.

The multilayered cover system (including the minimum random fill zone) is a minimum of six

feet thick. The radon barrier consists of the layers above the random fill zone, and is 4.5 feet

thick. The uniform cover system has the same total thickness as the multilayered system, with

the layers outlined below.

1. Topsoil layer (0.5 feet thick) to provide the seedbed and upper portion of a plant growth zone.

2. Clayey sand layer (4.0 feet thick) of soils from the Northwest Borrow area or Old Ponds borrow area, to provide a subsoil layer for water retention and vegetation.

3. Random fill zone (with a minimum thickness of 1.5 feet when directly above tailings) of soils from the Old Ponds area to provide a zone of separation between tailings or mill materials and the remaining cover system, as well as to provide a firm base for compaction of the clay layer.

A comparison of the two cover systems is summarized in the table below.



Cover Item Multilayered Cover System Uniform Cover System Materials and construction Material and compaction More general material and (using Northwest and Old specifications necessary for clay compaction specifications for Ponds borrow area soils) layer and other layers uniform subsoil layer Estimated net infiltration (from 0.8 inches per year during wet 0.1 inches per year during wet Appendix F) for 2-ft root depth year; lower daily wet-period flux year; higher daily wet-period flux and 4.5-ft thick radon barrier Vegetation root zone Root depth limited to top of clay Root depth to bottom of radon

layer (3.5 ft) barrier (4.5 feet)

5.3 Static and Seismic Stability

The slope stability of the reclaimed tailings embankments was evaluated under conservative

long-term static and seismic conditions. The stability analysis method and results are presented

in Appendix E. These analyses show that the reclaimed embankments for the Primary and

Secondary Impoundments have acceptable, calculated factors of safety against embankment

movement under long-term static conditions. The reclaimed embankments also have acceptable

calculated factors of safety under conservative seismic conditions. Seismic input to this

evaluation is presented in Appendix E and summarized in Section 2.2.

Based on the 1999 cone penetrometer testing on tailings in the Primary Impoundment (Appendix

A), liquefaction analyses of the tailings were conducted (described in Appendix E). These

analyses also show that the tailings in the Primary Impoundment are not likely to liquefy from

seismic activity under their current relative density conditions. Although the tailings in the

Secondary Impoundment were not evaluated with cone penetrometer testing, these tailings are

not likely to liquefy due to their being at a higher relative density than the tailings in the Primary

Impoundment. The confinement of cover and random fill materials over the tailings in both

impoundments will further reduce the potential for liquefaction.

5.4 Radon Emanation

In 1999, tailings characterization work was conducted for Cotter by Shepherd Miller, Inc. The

objective of the work was to assess the hydraulic properties of tailings accessible for testing

(tailings above the pond water level in the Primary Impoundment at that time). This work was

conducted as part of the conditions for renewed tailings disposal in the Primary Impoundment



outlined in Section 3.4. As part of this work, tailings and interim cover samples were collected

and tested for geotechnical and radiological properties (Appendix A). These properties were

reviewed with respect to previous radon emanation modeling of the cover system (WWL, 1990

and ESCI, 1995). The review of tailings and cover material parameters is presented in Appendix

B, and updated radon emanation modeling is presented in Appendix D.

The radon emanation modeling in ESCI (1995) was based on sampling and testing documented

in WWL (1990). These values were compared with measured values from the 1999

investigation work in Appendix B. These updated values were used in the radon emanation

modeling (Appendix D). The modeling results show that the approved cover system reduces the

rate of radon-222 emanation to less than 20 picocuries per square meter per second for all of the

scenarios that were evaluated. These results are based on conservative scenarios of radon barrier

directly over tailings or random fill, soils with radium-226 values in the random fill layer, and no

topsoil layer. The evaluation also considered ingrowth of radium-226 from decay of thorium

230 in random fill and tailings.

5.5 Erosion Protection

The erosional stability of the reclaimed impoundment was evaluated in terms of long-term wind

erosion and water erosion under extreme storm conditions. Wind erosion of the cover system

was evaluated in ESCI (1995), with no predicted soil loss due to wind erosion. Since the

features affecting wind erosion have not changed with the updated reclamation plan, no

additional wind erosion analyses have been conducted.

An updated evaluation of the erosional stability of the cover surface, reclaimed embankment

slopes, and diversion channels was conducted using methods that have been updated since 1995.

These analyses are presented in Appendix C. The results are generally consistent with those in

ESCI (1995): (1) the cover surface is erosionally stable with a vegetated cover, (2) the reclaimed

embankment slope requires rock protection for erosional stability, and (3) the diversion channels

require rock protection for erosional stability.



In 1998, Cotter conducted an evaluation of potential riprap sources on or near the Milling

Facility (Cotter, 1998). The results of this evaluation are presented in Appendix C, and showed

that a commercial riprap source near Canon City can provide the projected quantity of material

(over 80,000 cubic yards) with a median rock size (D50) of nine inches. Durability testing of a

sample of this material resulted in a score of above 80, indicating that the material meets NRC

durability criteria with no oversizing (NRC, 1990; Johnson and others, 1998). The commercial

source of rock near Canon City would be the preferred source of durable rock for erosion

protection on the reclaimed embankment slopes and in the diversion channels and outlet

channels.

5.6 Infiltration

Infiltration of precipitation through the multilayered cover system was evaluated in ESCI (1995)

using the HELP model. Using conservative precipitation and liner system conditions, average

infiltration through the cover system was estimated to be approximately 0.017 gpm/acre (ESCI,

1995). This rate is equivalent to approximately 0.34 inches per year per square foot, or

approximately 2.6 percent of average annual precipitation.

Additional infiltration analyses were conducted for the updated reclamation plan with the multi

layered cover using the current version of the HELP model (Schroeder and Aziz, 1997). The

analysis results are presented in Appendix F, with average infiltration rates of 0.46 to 0.53 inches

per year per square foot of cover, or approximately 3.2 to 3.7 percent of average annual

precipitation. These values are similar to those presented in ESCI (1995), and provide a basis for

comparison with the uniform cover system.

Infiltration of precipitation for the updated reclamation plan was evaluated using the

VADOSE/W unsaturated flow model. The multi-layered and homogeneous cover systems were

evaluated under varying precipitation conditions on a daily time-step basis for a 20-year

simulation period (presented in Appendix F). For average precipitation conditions, both cover

systems showed no net annual infiltration. For wet-year precipitation conditions, The

multilayered cover system showed a net annual infiltration of 0.8 inches, and the uniform cover

systems showed a net annual infiltration of 0.1 inches. This evaluation showed that the uniform



cover system provides a barrier to infiltration that is as effective as the multi-layered cover

system.

5.7 Biointrusion and Other Environmental Factors

Root depth. The typical root depth of grass species planned for the cover surface (from WWL,

1990) is approximately 1.2 feet. Conversations with Fremont Soil Conservation Service

personnel indicate a variable root depth for grass species ranging up to 3 feet (depending on

moisture and soil conditions). The available plant growth zone for the multilayered and uniform

cover systems provides this depth for root penetration.

Frost depth. Vulnerability of the cover to freeze-thaw cycles was evaluated in ESCI (1995)

reviewed by Cotter since 1995. The clay layer in the multi-layered cover system is 3.5 feet

beneath the cover surface, and the bottom of cover for the uniform cover system is 4.5 feet

beneath the cover surface. Both are below the predicted average frost depth in the Canon City

area of Fremont County (2.3 feet).

Biointrusion. Vulnerability of the cover system to biointrusion from plant species is limited by

thickness of the cover system relative to the rooting depth of planned vegetation (as discussed

above). Some passive maintenance would be required for management of undesirable weeds and

brushy species with deeper root systems.

Biointrusion from burrowing vertebrates into the mill tailings is mitigated by the thickness of the

cover and random fill above the tailings. The minimum six-foot depth of radon barrier and

random fill exceeds the typical burrowing depth of most vertebrates in the region (Waugh, 1997).

Biointrusion into the radon barrier would not significantly affect the rate of radon emanation

from the top of the cover.



6.0 MILL DECOMMISSIONING

The current plans for decommissioning of the Cotter Canon City Milling Facility are outlined in

Appendix I. These plans are consistent with the previous reclamation plan (ESCI, 1995), as well

as the procedures developed and used by Cotter Corporation for successful alkaline mill

demolition (completed in 1999).

6.1 Decommissioning Objectives

The project goals for mill decommissioning are outlined below.

1. Attain an as low as reasonably achievable (ALARA) dose outcome for: (a) workers doing the decommissioning, (b) other on-site personnel, and (c) off-site individuals.

2. Optimize the effectiveness of the mill decommissioning plan.

The implementation strategy to achieve the goals for mill decommissioning is listed below.

1. Utilize commercially available demolition equipment to minimize exposures by minimizing time and keeping personnel from close proximity to actual demolition activities.

2. Plan the components

3. Establish a work system

4. Train the work force

5. Work the plan

6. Evaluate the plan through project oversight and quality assurance

7. Modify and continuously improve the plan.

6.2 Decommissioning Strategy

The decommissioning plan for remaining mill facilities consists of the following major elements:

(1) documentation of health and safety procedures, (2) conducting pre-decommissioning

activities, (3) demolition of the above-ground facilities (removal of equipment and dismantling

of structural materials), (4) demolition of below-ground facilities (floor slabs, footings, and



underground utilities, (5) mill site area soils cleanup, (6) material disposal in the Primary

Impoundment, and (7) regrading and revegetation.

Although different types of decommissioning equipment will be used to demolish each different

type of structure or equipment, dismantling will proceed according to the general staging

process. The first stage consists of demolition of above-ground structures such as piping and

tanks, then buildings and enclosed structures. The second stage consists of concrete removal

(structure floor slabs, below-ground walls, and footings). The third stage consists of removal of

underground utilities (most likely conducted at the same time as concrete removal). The fourth

stage is excavation and removal of contaminated soils.

The plan in Appendix I describes these elements as well as the requirements prior to demolition

and the procedures to be used for specific sections or areas of the mill facilities. These elements

are summarized below.

6.3 Health and Safety Procedures

The health and safety procedures to be established prior to decommissioning are consistent with

current Cotter procedures and listed below.

1. General safety and hazard communications

2. Personal protection requirements

3. Occupational monitoring requirements

4. Environmental monitoring requirements

5. Administrative action levels

6. Medical emergency procedures

7. Fire protection

8. Water and contaminant management

9. Decontamination procedures for salvageable equipment

10. Operational issues



11. Quality assurance provisions

12. Project management, modification and improvement

13. Training

6.4 Pre-Decommissioning Activities

Pre-decommissioning activities consist of preparing the milling facility area for demolition.

These activities were completed by Cotter for the alkaline mill prior to its demolition. These

activities include removal of remaining process fluids, residual residues, reagents, products, and

other materials (where feasible) in order to reduce potential personnel exposure and

environmental exposure and facilitate demolition.

6.5 Demolition of Above-Ground Facilities

This consists of removal of equipment and dismantling of above-ground portions of structures.

Materials from demolition will be transported to the Primary Impoundment for disposal in a size

and shape compatible with the transport equipment and disposal methods.

The strategy for demolition is based on current equipment and procedures used for structural

demolition and used successfully at other uranium mill sites in the western United States. This

strategy consists of use of mechanized equipment specially designed for equipped for demolition

work, minimizing manual labor.

In contrast to the decommissioning of the alkaline mill, which was fairly labor intensive,

decommissioning of the existing mill will utilize heavy equipment. This equipment will allow

largely remote demolition of structures and buildings and loading of debris. Modern demolition

equipment will allow remote-controlled water sprays to be directed as necessary, will require

fewer staff, and will lower occupational exposures.



6.6 Demolition of Below-Ground Facilities

The below-ground facilities to be removed include concrete slabs and footings and buried

utilities. The utilities include water lines, electric lines, and gas lines. These materials will be

excavated and transported to and disposed in the Primary Impoundment.

6.7 Soils Cleanup

The depth and extent of soil excavation will be based on the “Bench Mark Dose” standard

outlined in Colorado Rules and Regulations Pertaining to Radiation Control, Part 18, Criterion 6,

subsection (6).

The key components of underlying soils cleanup are outlined below.

1. The criteria for soils cleanup include four land classifications, based on measured radioactivity: (a) Zone A, acceptable for public use without restriction, (b) Zone C, presently controlled but likely to be released for unrestricted use pending soil sampling results, (c) Zone L, controlled under the license with restricted use, and (d) Zone R, final repository (area to be transferred to U.S. Department of Energy for long-term care and maintenance).

2. Contaminated soils will be disposed of in the Primary Impoundment. Contaminated soils will be placed in the Primary Impoundment as random fill materials (material used to stabilize the underlying tailings, fill voids within mill material, achieve desired cover system slopes, and provide a firm base for construction of the cover system). Only uncontaminated soils meeting criteria for cover materials will be used in the cover system over the Primary and Secondary Impoundments.

6.8 Material Placement

Dismantled equipment and structural materials will be placed in the Primary Impoundment for

disposal according to the procedures listed below.

1. Material will be cut or dismantled into pieces that can be safely lifted or carried with the equipment being used. Material will also be cut or dismantled to minimize void spaces after disposal.

2. A backhoe, front-end loader, crawler or equivalent equipment will be utilized to crush or compact compressible materials. These materials will be laid out in a



staging area or other approved area to facilitate crushing or compacting with equipment.

3. Pipe or conduit with an opening or diameter larger than 12 inches that cannot be crushed will be filled with earthen materials prior to disposal.

4. Tanks, vessels, and vats will be handled according to the wall material and wall thickness. Tanks will be crushed or compacted if possible. Wooden vats will be dismantled. Tanks or vessels that cannot be crushed will be dismantled, if feasible. Tanks that cannot be crushed or dismantled will be transported to the Primary Impoundment, filled with earthen materials and buried.

5. Mill debris placement will be a minimum distance of 10 feet from the Primary Impoundment liner.

On-site soils will be placed in the Primary Impoundment with the disposed equipment and

structural materials, based on the objectives outlined below.

1. The fill is used to create a working surface above the disposed materials to allow construction equipment to travel over and compact the disposed materials, and to protect rubber-tired equipment from punctures.

2. The fill provides an interim cover over the disposed material to minimize exposure of mill materials to air and meteoric water.

3. The fill is used to minimize void spaces within the disposed materials and preclude future settlement. The lifts of fill and disposed material will be compacted by multiple passes with heavy equipment.

On-site soils may also be placed in the Secondary Impoundment to reach final grades and slopes

as random fill to set the final grade for cover system construction.



7.0 ADDITIONAL PLANS AND PERFORMANCE MONITORING

7.1 Additional Plans

Additional plans associated with tailings reclamation will be prepared prior to initiation of

tailings reclamation. Specific plans required by Cotter license condition or other requirements

(such as guidelines in NUREG-1620) are outlined below.

Cover Construction Plan. This plan would provide more detail about construction of the cover

over the Primary and Secondary Impoundments than the information included in previous plans

as well as this updated plan. A detailed plan would be submitted for agency review at least one

year prior to decommissioning of the Primary and Secondary Impoundments.

This plan would be adjusted for the final elevation of tailings in the Primary Impoundment and

the engineering characteristics of the near-surface tailings in the Primary and Secondary

Impoundments at the time of closure. The plan would include: (1) material specifications for

the soils to be used in the homogeneous cover; (2) the specifications for placement and

compaction of these materials; and (3) the frequency and methods for quality assurance testing of

the materials, construction procedures, and resulting thicknesses and grades. This plan would

include the elements of the Construction Verification Plan identified in CGS (1996). The major

components of the Cover Construction Plan are presented in Appendix J.

Rock Sampling and Analysis Plan. This plan would provide more detail about the selected

source of riprap and bedding materials to be used for erosion protection material on the

embankment slopes and drainage channels than that documented in Appendix C. This plan

would be submitted for agency review at least one year prior to decommissioning of the Primary

and Secondary Impoundments.

The plan would include: (1) size and durability specifications for the rock to be used as riprap;

(2) size specifications of filter and bedding materials beneath the riprap (as required); (3)

specifications for placement of these materials; and (4) the frequency and methods for quality



assurance testing of the materials, construction procedures, and resulting layer thicknesses. The

major components of this plan are presented in Appendix H.

Tailings Dewatering Plan. A detailed tailings dewatering plan would be prepared for the

Primary and Secondary Impoundments. This plan would be submitted for agency review at least

one year prior to decommissioning of the Primary and Secondary Impoundments.

The detailed tailings dewatering plan would include the procedures for removal or evaporation of

ponded water from the tailings surface as well as procedures for removal of extractable pore

water from the tailings, utilizing the existing dewatering network within the impoundments. The

objectives of the dewatering procedures are to enhance tailings consolidation and bearing

capacity for subsequent cover construction. The performance of the tailings drainage system and

an initial tailings dewatering plan (based on current information) are presented in Appendix K.

Settlement Monitoring Plan. Monitoring of tailings surface settlement will be conducted at the

end of operations to measure rates and locations of settlement prior to construction of the cover

system. After construction of the cover system, settlement monitoring will be conducted as part

of post-closure performance monitoring. A detailed settlement monitoring plan will be prepared

to outline the procedures and measurement frequency for monitoring and submitted for agency

review at least one year prior to decommissioning of the Primary and Secondary Impoundments.

A preliminary settlement monitoring plan (incorporating these elements) is presented in

Appendix J.

7.2 Performance Monitoring

The performance monitoring and verification tasks for the reclaimed tailings impoundments and

mill site are consistent with plans for overall site reclamation and review guidelines in NRC

(2002). Key tasks outlined below address the period of time from site reclamation until property

transfer to the U.S. Department of Energy.



Settlement. Settlement will be monitored with survey monuments installed on a grid system on

the impoundment cover surface. The monuments will be surveyed on a quarterly basis until four

quarters of stable conditions (less than 0.1 foot of settlement) are measured.

Vegetative Cover. A vegetation plan will be prepared for the impoundment surface outlining

the initial and mature species desired for the reclaimed impoundment surface and the schedule

and methods planned for achieving the mature vegetation (such as transplanting of seedlings and

institution of weed control). A cover of selected native grasses is planned for revegetation.

After establishment of the initial vegetation on the cover surface, the condition of the initial

vegetation will be monitored for comparison with the schedule in the vegetation plan. The

vegetation performance will be monitored by Cotter until that responsibility is changed with

property transfer to the U.S. Department of Energy.

Erosional Stability. The erosional stability of the cover surface will be monitored on a semi

annual basis, most likely at the same time as vegetation monitoring. Elements of the erosional

stability monitoring are degree of vegetation cover (in terms of surface coverage), identification

of settled or ponded areas (such as on the top surface), and identification of rills, gullys, or other

areas of runoff concentration. Areas that are identified will be monitored to determine if

corrective action is necessary. Corrective action would include fill placement with topsoil or

placement of erosion-resistant materials on the surface, such as rock mulch.

Groundwater Protection. Groundwater protection will be continued under current site

requirements with CDPHE.



8.0 REFERENCES

Colorado Department of Public Health and Environment, Radiation Control Division (CDPHE), 1996. "Decision Analysis for Proposed Amendment to Colorado Radioactive Materials License 369-01, June 18.

Colorado Geological Survey (CGS), 1996. "Final Draft, Technical Evaluation Report for Cotter Corporation's Application for Amendment to Radioactive Materials License 369-01, May 1996," prepared for Colorado Department of Public Health and Environment, Radiation Control Division, May.

Cotter Corporation (Cotter), 2005. “Environmental and Occupational Performance Report and ALARA Review, Calendar Year 2004.” June 30.

Cotter Corporation (Cotter), 2003. Letter from Steve Landau to Eugene Potter, Colorado Department of Public Health and Environment, Laboratory and Radiation Services Division (CDPHE), April 16.

Cotter Corporation (Cotter), 1999. Letter to Colorado Department of Public Health and Environment, Hazardous Materials and Waste Management Division (Philip Stoffey) from David Munger concerning rock borrow source material, February 22.

Cotter Corporation (Cotter), 1998. Letter to Colorado Department of Public Health and Environment, Hazardous Materials and Waste Management Division (Philip Stoffey) from David Munger concerning preliminary rock borrow source sampling program, December 7.

Cotter Corporation (Cotter), 1996. "Cotter Corporation Environmental Report, Canon City Mill, Fremont County, Colorado," prepared for Colorado Department of Public Health and Environment, Radiation Control Division, April.

Cotter Corporation (Cotter), 1994. Title X Report to U.S. Department of Energy.

Cotter Corporation (Cotter), Colorado Department of Public Health and Environment, and U.S. Environmental Protection Agency, 1995. “Liquids and Solids Management Plan.” Total Quality Environmental Management (TQEM) Project Report. December.

De Puy, G.W., 1965. "Petrographic Investigations of Rock Durability and Comparisons of Various Test Procedures," Engineering Geology, Vol. 2, No. 2, July.

Earth Science Consultants, Inc. (ESCI), 1995. "Decommissioning and Reclamation, Chapter 9," prepared for Cotter Corporation and included in the Cotter Corporation Application for Amendment to Radioactive Materials License 369-01, December.



International Conference of Building Officials (ICBO), 1991. Uniform Building Code, 1991 Edition.

Interstate Technology and Regulatory Council (ITRC), 2003. Technical and Regulatory Guidance of Design, Installation, and Monitoring of Alternative Final Landfill Covers, ALT-2. Washington D.C. December, http://www.itrcweb.org.

Johnson, T.L., 2002. “Design of Erosion Protection for Long-Term Stabilization.” U.S. Nuclear Regulatory Commission (NRC), NUREG 1623, Final Report, September.

Johnson, T.L., 1999. “Design of Protective Covers.” U.S. Nuclear Regulatory Commission (NRC), NUREG-2615, Draft for Comment. February.

Johnson, T.L., S.R. Abt, C.I. Thornton, and P.Y. Julien, 1998. "Design of Erosion Protection for Long-Term Stabilization," NUREG-1623, Draft, prepared for U.S. Nuclear Regulatory Commission, December.

Keshian, B., and R.E. Rager, 1988. "Geotechnical Properties of Hydraulically Placed Uranium Mill Tailings," Hydraulic Fill Structures, D.J.A. van Zyl and S.G. Vick, Eds., Geotechnical Special Publication 21, ASCE, pp 227-254.

Linsay, C.G., L.W. Long, and C.W. Begej, 1982. "Long-Term Survivability of Riprap for Armoring Uranium Mill Tailings and Covers: A Literature Review," NUREG/CR-2642, prepared for U.S. Nuclear Regulatory Commission, June.

Linsley, R.K., M.A. Kohler, and J.L.H. Paulhus, 1975. Hydrology for Engineers, McGraw-Hill Book Company.

National Oceanic and Atmospheric Administration (NOAA), 1988. Hydrometeorological Report HMR No. 55A, Probable Maximum Precipitation Estimates – United States Between the Continental Divide and the 103rd Meridian, U.S. Department of Commerce. June.

Rogers, V.C., K.K. Nielson, and D.R. Kalkwarf, 1984. "Radon Attenuation Handbook for Uranium Mill Tailings Cover Design," NUREG/CR-3533, prepared for U.S. Nuclear Regulatory Commission, April.

Schroeder, P and Aziz, N, 1997, Hydrologic Evaluation of Landfill Performance, HELP Version 3.07. Environmental Laboratory USAE Waterways Experiment Station.

Shepherd Miller, Inc. (SMI), 2000. "Tailings Investigation Report for the Canon City Milling Facility, Canon City, Colorado," prepared for Cotter Corporation in draft form, December 22, 1999; completed for Cotter Corporation November 30, 2000.



Shepherd Miller, Inc. (SMI), 1998. "Canon City Mill Tailings Management Alternative Evaluation," prepared for Cotter Corporation, December 31.

U.S. Army Corps of Engineers (COE), 1982. "Engineering and Design Stability for Earth and Rockfill Dams," EM 1110-2-1902.

U.S. Geological Survey (USGS), 2005. NEIC: Earthquake Search Results, USGS Earthquake Data Base.

U.S. Nuclear Regulatory Commission (NRC), 2003. “Standard Review Plan for the Review of a Reclamation Plan for Mill Tailings Sites Under Title II of the Uranium Mill Tailings Radiation Control Act of 1978.” NUREG-1620, Revision 1, June.

U.S. Nuclear Regulatory Commission (NRC), 1990. "Final Staff Technical Position, Design of Erosion Protection Covers for Stabilization of Uranium Mill Tailings Sites," August.

U.S. Nuclear Regulatory Commission (NRC), 1989. "Calculation of Radon Flux Attenuation by Earthen Uranium Mill Tailings Covers," Regulatory Guide 3.64, Office of Regulatory Research, June.

Wahler, W.A. and Associations (Wahler), 1980. “First Stage Construction Report, Cotter Corporation, Uranium-Vanadium Tailings Impoundment,” July.

Water, Waste and Land, Inc. (WWL), 1990. "Canon City Tailings Basin Reclamation Plan," prepared for Cotter Corporation, January.

Waugh, W.J., 1997. “Ecology of Uranium Mill Tailings Covers,” in Landfill Capping in the Semi-Arid West: Problems, Perspectives, and Solutions, T.D. Reynolds and R.C. Morris, Eds., Environmental Science and Research Foundation, pp 199-212.


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