Solid Waste and EPA-542-R-11-002
Emergency Response March 2011
(5203P) www.epa.gov
Focused Review of Specific
Remediation Issues
An Addendum to the Remediation
System Evaluation for the
Homestake Mining Company (Grants)
Superfund Site, New Mexico
Region 6
-------
Focused Review of Specific Remediation Issues
An Addendum to the Remediation System Evaluation
for the
Homestake Mining Company (Grants) Superfund Site, New Mexico
Final Report
December 23, 2010
Prepared by US Army Corps of Engineers
Environmental and Munitions Center of Expertise
For US Environmental Protection Agency, Region 6
9
I
US Army Corps of Engineers
Environmental and Munitions
Center of Expertise
US Environmental
Protection Agency
-------
Executive Summary
The current evaluation of the remediation efforts at the Homestake Mining Company
(Grants) Superfund site has been conducted on behalf of the US Environmental
Protection Agency (US EPA) by the US Army Corps of Engineers Environmental and
Munitions Center of Expertise. The evaluation is intended to supplement the previous
Remediation System Evaluation (RSE) conducted for the site by Environmental Quality
Management (EQM, 2008). Specific issues remaining from the RSE, as identified in the
Scope of Work (Appendix A), have been addressed through data analysis and conceptual
design, including:
1) Evaluate the capture of contaminant plumes in the alluvial and Chinle aquifers.
2) Evaluate the overall strategy of flushing contaminants from the large tailings
pile with discharge of wastes to on-site evaporation ponds and to identify and
compare alternatives.
3) Assess potential modifications to the current ground water treatment plant to
improve capacity.
4) Evaluate the projected evaporation rates for the existing on-site ponds and for
a proposed evaporation pond west of the on-site tailings piles, as it may affect
the restoration activities at the site.
5) Assess the adequacy of the monitoring network at the site.
6) Evaluate the current practice of irrigating with untreated water.
7) Evaluate the smaller of the two tailings piles at the site as a potential source of
contamination and the future need for a more conservative cap than the radon
barrier.
A process fostering involvement and input from various stakeholders had been
developed soon after the initiation of the project and has been very helpful in focusing
and facilitating the analysis.
The analysis of current and past environmental conditions as well as the current and
past operations of the extraction, injection, and treatment systems has been conducted by
the USAGE EM CX following a site visit in April, 2009. It appears that the current
remediation systems have been making significant progress in improving ground water
quality at the site and Homestake Mining Company has been diligently working in good
faith toward restoring the environment. There are a number of major conclusions from
the evaluation of the efforts.
• Ground water quality restoration is very unlikely to be achieved by 2017
with the current strategy.
• Flushing of the large tailings pile is unlikely to be fully successful at
removing most of the original pore fluids or to remediate the source mass
present in the pile due to heterogeneity of the materials.
Final 12/23/10
-------
• Long screened intervals in wells complicate the interpretation of water
quality in and below the large tailings pile.
• The vicinity of the former mill site may be an additional source of
contaminants.
• Control of the contaminant ground water plumes seems to depend on both
hydraulic capture and dilution.
• There may have been widespread impacts on the general water quality (e.g.,
ions such as sulfate) of the alluvial aquifer since mill operations began, but
the limited amount of historical data precludes certainty in this conclusion.
• Upgradient water quality has declined over time, primarily in the western
portion of the San Mateo drainage and this may be affecting concentrations
in northwestern portions of the study area.
• Ground water modeling has generally been done in accordance with
standard practice. The seepage modeling likely overestimates the efficiency
of flushing of the tailings.
• The control of a uranium plume in the Middle Chinle aquifer may be
incomplete.
• There are no readily apparent site-related impacts to the San Andres aquifer
though data are limited. San Andres well 0943, located at the western end
of Broadview Acres, had an increase in uranium concentrations in 2002, but
concentrations since then have been relatively stable.
• There is no indirect evidence of leakage from the evaporation and collection
ponds, though the interpretation of water level and concentration data are
complicated by the significant injection and extraction conducted in the
immediate vicinity of the ponds.
• Current constraints to treatment plant operations include the evaporative
capacity of the ponds, clarifier operations, and possibly reverse osmosis
capacity.
• Evaporation rates for the ponds at the site are likely to be in the 65-80 gpm
on an annual basis when accounting for climatic conditions and salinity of
the pond contents.
• The monitoring program at the site is extensive and not clearly tied to
objectives. There may be redundancies in the network in a number of
locations in the alluvial aquifer. Additional monitoring points are necessary
in the Upper and Middle Chinle aquifers to better define plume extent and
11
Final 12/23/10
-------
migration. Monitoring frequency is irregular but generally from semi-
annual to annual. Air particulate monitoring appears adequate to assess
anticipated effluent releases from the site; however, there is a need to
confirm assumptions. The potential for release of radon from the
STP/evaporation pond area should be assessed.
• Irrigation with contaminated water has resulted in accumulation of site
contaminants in the soil of the irrigated land. These accumulations are
unlikely to migrate to the water table over time, however.
• Water used for irrigation could be successfully treated with a two-step ion-
exchange process.
Based on the analysis conducted, a number of recommendations are offered.
• The flushing of the tailings pile should be ended. If this is not adopted, a
pilot test of the potential for rebound in concentrations should be conducted
in a portion of the tailings pile. Monitoring should be conducted in depth-
specific wells with short screen lengths.
• Simplification of the extraction and injection system is necessary to better
focus on capture of the flux from under the piles and to significantly reduce
dilution as a component of the remedy.
• Further evaluate capture of contaminants west of the northwestern corner of
the large tailings pile.
• If not previously assessed, consider investigating the potential for
contaminant mass loading on the ground water in the vicinity of the former
mill site.
• Additional collection of geochemical parameters, including dissolved
oxygen and oxidation reduction potential, of the groundwater beneath and
downgradient of the LTP to characterize the geochemical environment and
the role that reducing conditions induced by the flushing have had in
immobilization of the selenium (and the potential that cessation of the
flushing may lead to less reducing conditions and release of the selenium).
• If the field pilots to reduce uranium concentrations in the groundwater
through adsorption or in-situ precipitation are approved and the results from
the pilots are promising, apply in larger scale to applicable portions of the
LTP and the groundwater.
• Further investigate the extent of contaminants, particularly uranium, in the
Upper and Middle Chinle aquifers and resolve questions regarding
dramatically different water levels among wells in the Middle Chinle.
in
Final 12/23/10
-------
• Consider geophysical techniques, such as electrical resistivity tomography
to assess leakage under the evaporation ponds.
• Assure decommissioning of any potentially compromised wells screened in
the San Andres Formation is completed as soon as possible.
• Consider construction of a slurry wall around the site to control contaminant
migration from the tailings piles. The decision for implementing such an
alternative would depend on the economics of the situation. Note that
HMC has reportedly considered a slurry wall in the past, and not found the
economics favorable. We recommend revisiting this issue in light of current
conditions.
• Relocation of the tailings should not be considered further by any means
given the risks to the community and workers and the greenhouse gas
emissions that would be generated during such work.
• Consider either the pretreatment of high concentration wastes in the
collection ponds as is currently being pilot tested, or adding RO capacity to
increase treatment plant throughput and reduce discharge to the ponds.
• Review of the spray evaporation equipment and potential optimizations of
the equipment to increase the rate and efficiency of evaporation.
• Selection of the area of the additional pond based on the evaporative
capacity needed after optimization of the treatment and evaporative spraying
systems and operations.
• Develop a comprehensive, regular, and objectives-based monitoring
program.
• Quantitative long-term monitoring optimization techniques are highly
recommended.
• Adjust Air Monitoring Program to perform sampling of radon decay
products to confirm equilibrium assumption, consider use of multiple radon
background locations to better represent the distribution of potential
concentrations and assess the radon gas potentially released from the
evaporation ponds, especially during active spraying.
• Though risks appear minimal with the current irrigation practice, consider
treatment of contaminated irrigation water via ion exchange prior to
application as a means to remove contaminant mass from the environment.
IV
Final 12/23/10
-------
Table of Contents
Section
Page
1. Introduction. 1
1.1. Brief Chronology of RSE and RSE Addendum Effort
1.1.1. Original RSE
1.1.2. RSE Addendum Objectives and Scope of Work
1.2. USACE Project Team
1.3. RSE Advisory Group
1.4. Condensed Overview of Site
1.4.1. History and Surrounding Land Use
1.4.2. Site Hydrogeology
1.4.3. Contaminants
1.4.4. Extraction and Injection Systems
1.4.5. Treatment Sy stem
1.4.6. Evaporation Ponds
2. Conceptual Site Model
2.1. Sources
2.1.1. Conditions in the Tailings Piles
2.1.2. Vicinity of Mill Site
2.1.3. Evaporation Ponds
2.1.4. Irrigated Acreage
2.2. Pathways/Affected Media
2.2.1. Air
2.2.2. Soil
2.2.3. Groundwater
2.3. Receptors
3. Adequacy of Plume Control
3.1. Hydraulic Capture
3.2. Concentration Trends
3.3. Groundwater Flux
3.4. Ground-Water Modeling
3.5. Chinle Aquifer Contaminant Control
3.6. Impacts to the San Andres Aquifer
4. Overall Remedial Strategy
4.1. Flushing of Large Tailings Pile
4.2. Downgradient Extraction and Injection
4.3. Evaporative Concentration of Salts and Final Entombment of Wastes
4.4. Alternative Strategies
4.4.1. Slurry Wall
4.4.2. Permeable Reactive Barrier
4.4.3. In-Situ Immobilization
4.4.4. Removal of Tailings
4.4.5. Alternative Energy Potential at the Homestake Site
Recommended Modifications to the Existing Treatment Plant
5.1. Evaluation Basis
5.2. System Constraints
1
1
1
2
2
3
O
O
4
4
5
5
6
6
6
6
6
7
7
7
7
7
7
11
11
11
16
16
17
17
18
18
22
23
25
25
26
28
30
35
36
36
36
Final 12/23/10
v
-------
Section Page
5.3. Alternatives to Current Treatment Operation 36
6. Evaporation Rates and Need for Additional Evaporation Capacity 39
6.1. Estimate of Lake Evaporation Assuming Fresh Water 39
6.2. Effect of Salinity 39
6.3. Need for Additional Evaporative Capacity 39
7. Groundwater Monitoring Network and Air Monitoring Program 41
7.1. Groundwater Monitoring 41
7.1.1. Environmental Monitoring Obj ectives 41
7.1.2. Monitoring Network 42
7.1.3. Monitoring Frequency 42
7.1.4. Sampling Methodology and Analytical Suite 43
7.1.5. Further Optimization Opportunities 43
7.2. Air Monitoring Program 43
7.2.1. Environmental Monitoring Objectives 43
7.2.2. Monitoring Network 44
7.2.3. Monitoring Frequency 45
7.2.4. Sampling Methodology and Analytical Suite 46
7.2.5. Further Optimization Opportunities for the Site Monitoring 46
8. Irrigation with Contaminated Water 48
8.1. Risk Issues 48
8.1.1. Uranium Radiological Dose/Risk Estimation 48
8.1.2. Selenium Soil Screening Level Comparison 50
8.1.3. EPA Risk Assessment 50
8.2. Future Alternatives 50
8.2.1. Treatment of Irrigation Water 50
8.2.2. Reduction of the Mobility of Uranium in Soil 51
9. Summary of Conclusions and Recommendations 52
9.1. Conclusions 52
9.2. Recommendations 53
9.3. Approach to Implementation of Recommendations 55
10. References 57
Appendices
A RSE Addendum Scope of Work
B Communications Plan
C Output from Sustainable Remediation Tool
D Pond Evaporation Calculations
E Evaporative Spraying Equipment Information
F RESRAD Summary Report
G Responsiveness Summary
Final 12/23/10
VI
-------
Item Page
Tables
1 Homestake Mine Slurry Wall Construction Estimate 26
2 Homestake Mine PRB Wall Construction Estimate 28
3 Estimate for Removal of All Tailings/Waste and Off-Site Disposal
at a Newly Constructed 10 CFR 40 Compliant Cell 31
4 Comparison of Energy Usage, Carbon Emissions, and Accident Risk
for Current Remedial Approach and Alternative Remedies 33
5 Cost Estimate for Slurry Transport of Homestake Tailings 34
6 Comparison of Average Flow Rates and Species Concentrations
for Current and Proposed Treatment Systems Feed 38
7 Summary of Estimated Dose for Resident on Irrigated Land 49
8 Summary of Estimated Excess Cancer Risk for Resident
on Irrigated Land 49
9 Average Concentrations of Species in Homestake Untreated
Irrigation Water 51
Figures
la Site Location 8
Ib Well Locations 9
2 Conceptual Site Model Summary 10
3 Well X Uranium Concentration Trends 11
4 Well K4 Uranium Concentration Trends 12
5 Well ST Uranium Concentration Trends 12
6 Well S2 Uranium Concentration Trends 13
7 Well B4 Uranium Concentration Trends 13
8 Well Sll Uranium Concentration Trends 13
9 Well Sll Sulfate Concentration Trends 14
10 Well 0654 Uranium Concentration Trends 14
11 Well 0854 Uranium Concentration Trends 15
12 Well 0882 Uranium Concentration Trends 15
13 Well DD Uranium Concentration Trends 16
14 Uranium Concentrations in Large Tailings Pile 19
15a Uranium Concentrations in Select Wells, Western Large Tailings Pile 20
15b Uranium Concentrations in Select Wells, Eastern Large Tailings Pile 20
16 Uranium Concentrations in Select Sumps 21
17 Water Levels in Evaporation Ponds and Nearby Wells 24
18 Water Levels in Evaporation Ponds and Other Nearby Wells 24
19 Well K4 Sulfate Concentrations 25
20 Well KZ Sulfate Concentrations 25
21 Air Monitoring Locations 47
vn
Final 12/23/10
-------
1 INTRODUCTION
1.1 Brief Chronology of the Remediation System Evaluation (RSE) and RSE
Addendum Effort. The US Environmental Protection Agency (EPA) Region 6 had
originally requested a review of the performance of the ground water remedy at the
Homestake Superfund site. The site was used for milling of uranium ore and includes
two tailings piles. The operations and leaching of liquids from the mill site and tailings
piles has contaminated ground water in the vicinity of the site.
1.1.1 Original RSE. The original RSE for the Homestake Mining Company
(Grants) Superfund Site (Homestake Site) was conducted by Environmental Quality
Management (EQM) under contract to the EPA Risk Management Research Lab in
Cincinnati in 2008. A draft report was submitted in August 2008, and a draft final report
was submitted in December, 2008 (EQM, 2008). The draft final report was accompanied
by responses to comments provided by various stakeholders, including:
the State of New Mexico,
- members and consultants of the Bluewater Valley Downstream
Alliance (BVDA), and
Homestake Mining Company.
The RSE report described the site conditions and the current remedy, as well as
provided several recommendations. Based on stakeholder comments, EPA determined
that there were additional issues that needed to be addressed regarding the implemented
remedy at the site. Through Headquarters, US EPA, the US Army Corps of Engineers
(USAGE) Environmental and Munitions Center of Expertise (EM CX) was tasked to
perform a follow-on study (the RSE "Addendum") to address a number of remaining
issues.
1.1.2 RSE Addendum Objectives and Scope of Work. The goals of the RSE
addendum were to consider the following major issues:
the performance of the current approach to protecting, restoring, and
monitoring ground water quality
- the need for changes to the ground water treatment system
the appropriateness of irrigation of crop land with contaminated
groundwater
To accomplish these goals, a scope of work was developed in conjunction with the
stakeholders, including those listed above as well as the Pueblo of Acoma and their
consultants, the Nuclear Regulatory Commission (NRC), and local residents. The scope
of work included seven tasks (generalized below - the complete scope of work is
provided as Appendix A):
Final 12/23/10
-------
1) Evaluate the capture of contaminant plumes in the alluvial and Chinle
aquifers.
2) Evaluate the overall strategy of flushing contaminants from the large
tailings pile with discharge of wastes to on-site evaporation ponds and
to identify and compare alternatives.
3) Assess potential modifications to the current ground water treatment
plant to improve capacity.
4) Evaluate the projected evaporation rates for the existing on-site ponds
and for a proposed evaporation pond west of the on-site tailings piles,
as it may affect the restoration activities at the site.
5) Assess the adequacy of the monitoring network at the site.
6) Evaluate the current practice of irrigating with untreated water.
7) Evaluate the smaller of the two tailings piles at the site as a potential
source of contamination and the future need for a more conservative
cap than the radon barrier.
The organization of this report generally follows this list of tasks.
1.2 US ACE RSE Addendum Project Team. The RSE Addendum was prepared
by personnel from the USAGE EM CX in Omaha, Nebraska, including:
Dr. Carol Dona, Chemical Engineer
Mr. Brian Hearty, Health Physicist
Mr. Dave Becker, Geologist
1.3 RSE Advisory Group. The RSE Addendum effort was significantly aided
by input from a diverse and involved group of stakeholders. The representatives of the
stakeholders included:
Acoma Pueblo. Ms. Laura Watchempino, Haaku Water Office
Blue Valley Downstream Alliance. Ms. Candace Head-Dylla, Mr.
Milton Head, Mr. Art Gebeau, Dr. Richard Abitz, consultant to
BVDA, Mr. Chris Shuey and Mr. Paul Robinson, Southwest Research
and Information Institute, consultants to BVDA and Acoma Pueblo..
Homestake Mining Co./Barrick Gold, Mr. Al Cox, Mr. Dan Kump,
Mr. George Hoffman, Hydro-Engineering LLC, consultant to
Homestake
New Mexico Environment Department. Mr. Jerry Schoeppner, Mr.
David Mayerson
Nuclear Regulatory Commission. Mr. John Buckley
- US EPA. Mr. Sairam Appaji, Remedial Project Manager, Mr. Donn
Walters, EPA Region 6 in Dallas, TX; Ms. Kathy Yager, HQ EPA; Dr.
Robert Ford, EPA National Risk Management Research Laboratory,
Cincinnati, OH
Final 12/23/10
-------
The interaction between EPA, the RSE Addendum team, and the RSE advisory group
was governed by a Communications Plan (provided as Appendix B). A joint site visit
including the RSE Addendum team and many of the stakeholders was conducted April
21-23, 2009. Subsequently, a number of phone conferences were held to clarify the
scope of the RSE Addendum effort, and to report on its progress. Valuable input was
obtained through this process.
1.4 Condensed Overview of Site. The previous RSE report provided a general
overview of the site conditions and current remediation system. A more complete
description is also provided in the Annual Reports provided by Homestake per their NRC
license. A brief synopsis of the site history, geology, restoration actions, and restoration
requirements is provided below.
1.4.1 History and Surrounding Land Use. The HMC Superfund Site is located
5.5 miles north of Milan, New Mexico, along the west side of State Highway 605. The
surrounding area is used for residential, agricultural, and commercial purposes. Five
low-density residential subdivisions, Murray Acres, Broadview Acres, Pleasant Valley
Estates, Felice Acres, and Valle Verde are located within two miles south and southwest
of the site. Large areas north and west of the site are largely unused except for grazing.
HMC (and, for a period of time early in its history, its corporate partners) operated a
uranium ore mill at the site from 1958 until 1990 using alkaline leach methods. Tailings
from the mill operations, entrained in solutions from the milling process, were placed into
lagoons on the top of two disposal piles at the site. These piles were closed and covered
by interim covers upon closure of the mill. Windblown materials from the tailings piles
were scraped from surrounding areas and placed on the piles before covering. The mill
was decommissioned and demolished between 1993 and 1995. The debris was buried at
the former mill site. All work has been conducted under license from the NRC. The site
setting is shown on Figure la.
1.4.2 Site Hydrogeology. The Homestake site is underlain by unconsolidated
alluvial materials resting on the incised surface of the Late Triassic Chinle Formation.
The alluvial materials are a heterogeneous mixture of sand, silt, and gravel and comprise
an aquifer with estimated hydraulic conductivities ranging from 10 to 800 feet/day.
Saturated thicknesses range from 0 to over 60 feet in the unconsolidated aquifer,
including a filled channel that underlies the large tailings pile. Depth to water is 40-60
feet at the site. Though the Chinle Formation is largely comprised of shale, there are
three water-bearing units within the Chinle, including the Upper and Middle Chinle
sandstones, and the Lower Chinle "aquifer" consisting of a zone of enhanced water yield.
A regional aquifer, the Permian-age San Andres Formation, exists at depth below the site,
and predominantly consists of limestone with subsidiary sandstones and shale. The
bedrock units have been tilted and faulted in the vicinity of the site. As a result, the
different Chinle aquifers are in contact with the base of the overlying alluvial aquifer in
areas of the site. Water exchange occurs between the various aquifers and "mixing
zones" have been identified between the alluvial aquifer and the Chinle aquifers.
Faulting has isolated some segments of the bedrock aquifers from others and from the
Final 12/23/10
-------
alluvial aquifer. Refer to the HMC Annual Reports or the RSE report for additional
information. Well locations are shown on Figure Ib.
1.4.3 Contaminants. Seepage from mill tailings wastes (i.e., Large Tailings Pile
and Small Tailings Pile) resulted in the contamination of groundwater with radioactive
and non-radioactive contaminants, including uranium, thorium-230, radium-226 and
radium-228, selenium, molybdenum, vanadium, sulfate, nitrate, chloride, and total
dissolved solids (TDS). Uranium, selenium, and sulfate have particularly impacted
downgradient ground water quality. Impacts are most widespread in the alluvial aquifer,
but contaminants have been identified in the Upper and Middle Chinle aquifers as well.
The concentrations in the alluvial aquifer are highest under and near the large and small
tailings piles and the former mill building location. Two plumes of uranium and
selenium extend southwestward near and under residential areas along preferential
ground water flow paths; one west of the site and the other south-southwest of the site.
There have also been impacts on the concentrations of dissolved solids, including sulfate,
in the alluvial ground water. Actual impacts by sulfate are difficult to discern from
background conditions, as historical data prior to mill operation are limited. Data for
samples collected in the 1950s from a couple of alluvial aquifer wells approximate 2.5
miles west of the site (well numbers 0935 and 0936) suggest significant increases in
sulfate concentrations have occurred. These wells are located in the Rio San Jose
alluvium and the cause for these increases is not known. Sulfate concentrations in
samples taken in 1960 from a well near what is now the northwest corner of the large
tailings were under 700 mg/L (Head, 2010, Comments on draft report), but are now,
according to the 2008 Annual Report, almost triple that in the same general area,
suggesting an impact on water quality over time. The proximity to the tailings implicates
the pile as the source. Ground water in the alluvial aquifer is expected to be largely
aerobic and would enhance the mobility of dissolved uranium and selenium.
The water in the tailings piles is, not surprisingly, highly contaminated. High
levels of site contaminants are present and dissolved solids content is also high (over
10,000 ppm). The water is largely a sodium sulfate water with significant levels of
carbonate and bicarbonate. There are limited oxidation reduction data for the water in the
piles, but limited data suggests the conditions are somewhat reducing with recent
oxidation-reduction potentials of-10 to -570 mV.
1.4.4 Extraction and Injection Systems. Ground water remediation and
contaminant plume control has been underway since the late 1970s at the site. The
current extraction and injection program is highly complex and not well documented.
Ground water is currently extracted from the alluvial aquifer downgradient of the
southwest corner of the large tailing pile, under the small tailings pile, upgradient of the
large tailing pile, and approximately 1A mile south-southeast of the small tailings pile.
Additional extraction takes place seasonally in the downgradient ends of the two uranium
plumes and this water is used for irrigation of crops on land owned by Homestake. The
water used for irrigation is contaminated by uranium and other site contaminants and is
applied without treatment. Accumulation of uranium in the soil of the irrigated acres is
routinely monitored. Extraction of water from the Upper Chinle aquifer is conducted
Final 12/23/10
-------
south of the large tailing pile and from the Middle Chinle aquifer north of the large tailing
pile. Additional extraction occurs within and just below the large tailings pile.
Injection of water occurs in conjunction with the extraction downgradient of the
large and small tailings piles, and 1A mile south-southeast of the small tailings pile.
Injection of water also occurs near the downgradient portions of the uranium and
selenium plumes downgradient of the site and into the Upper and Middle Chinle aquifers.
Water is also injected into the large tailings pile. Most of the water that is injected
around the site is clean water pumped from the San Andres formation. Total injection
flows into the alluvial aquifer are generally much higher than the total extraction rates.
1.4.5. Treatment System. The treatment plant treats some of the water extracted
from the alluvial aquifer and some of the water extracted from the large tailings pile.
Treatment consists of a clarifier (with lime addition), filtration primarily via sand filters,
and reverse osmosis (RO). The RO system includes both high and low-pressure units.
Brine from the RO system and some water extracted from the tailings are directly
disposed of in the on-site evaporation ponds. Solids from the clarifier and filtration
system also go to on-site ponds. The treatment capacity is nominally 600 gpm, but
practical limitations are less than that, particularly due to operation of the clarifier.
1.4.6. Evaporation Ponds. Wastes from the treatment plant and some solutions
extracted from the large tailings pile are discharged to on-site single-lined ponds for
evaporation and concentration of salts. The easternmost evaporation pond (#1) is single
lined and constructed on a portion of the top of the small tailings pile. Evaporation pond
#2 is located just west of Evaporation Pond #1 and is double lined. Two smaller
collection ponds are located west of Evaporation Pond #2. Sprayers are installed in the
two evaporation ponds to increase evaporative loss of water. Spraying is done seasonally
and only during times of low wind velocities. Evaporative capacity is reportedly a
limiting factor under the current remediation strategy and a new lined pond of 30 acres
surface area was approved by the NRC and NMED and is currently being constructed
west-northwest of the large tailings pile. At the time of completion of the ground water
remedy, the ponds would be covered and capped along with the tailing piles.
Final 12/23/10
-------
2 CONCEPTUAL SITE MODEL
2.1 Sources. The primary potential sources of contaminants at the site include the
two tailings piles and the former mill building site. The evaporation ponds and irrigated
acreage may represent secondary sources.
2.1.1 Conditions in the Tailings Piles. The conditions in the tailings piles
reflect the chemistry used in the milling process. A significant mass of uranium is still
present in the tailings. Reportedly, the uranium ore processed at the site had 0.04 to 0.3%
U3O8 content (Skiff and Turner, 1981). Assuming the ore had an average of 0.15%
uranium content and that the tailings had an average of 0.006% remaining uranium
(based on information in EPA 402-R-08-005, Table 3.13), the 22,000,000 tons of tailings
would contain approximately 2.6 million pounds of uranium, or approximately 2.5 times
the amount estimated to have been removed during the cleanup effort through 2008. The
redox (generally negative) and pH (near 10) conditions suggest the uranium in the piles
would be in the +6 state and mobile, but slight reductions in pH could result in some
reduction of the mobility of the uranium. Given that the uranium remaining the piles
represent what could not be fully extracted from the ore, it is possible the uranium is not
as accessible for dissolution, but it may slowly mobilize over time. It is possible that
without significant changes in the pore water chemistry, or the reduction of driving head
and infiltration through the pile, uranium mass could continue to leach into the
underlying native materials. The approach taken by Homestake assumes the uranium in
the pore fluid is mobile, but other uranium mass in the solids is immobile; however, there
are many pore spaces that contain fluid that are not significantly participating in the flow
if in fine-grained material or in dead-end pores. Based on a description of the tailings
discharge process provided by Homestake Mining, the conditions in the tailings pile are
likely heterogeneous with significant lateral and vertical variation in hydraulic properties
such that flow is far from uniform through the pile materials. The fluids in less mobile
zones may still diffuse out into the more permeable pathways during and after injection.
2.1.2 Mill Site. Though not specifically addressed in many of the available
reports, there is some suggestion in ground water monitoring data that the location of the
former mill buildings east of the large tailings pile was or is a source of contamination to
the ground water. Elevated uranium levels (up to over 40 mg/L in 2003) in some of the
"1" series wells have been observed there. The nature of the source is not clear.
2.1.3 Evaporation Ponds. The evaporation and collection ponds have
essentially been concentrating site contaminants, including uranium. Though there is no
evidence of leakage, the ponds could be a secondary source of contaminants affecting
air, soil, and ground water if the liners under the ponds were to leak, or if the ponds
become a source of radon or dust.
Final 12/23/10
-------
2.1.4 Irrigated Acreage. Application of uranium- and selenium-contaminated
ground water to irrigated land results in the accumulation of these elements in the soils.
These soils can then release contaminants into dust or to deeper soils and possibly ground
water through leaching processes. There is no evidence for impacts to ground water at
this time and future impacts are uncertain.
2.2 Pathways/Affected Media. The releases of contaminants from the primary
and secondary sources described above have either contaminated or may contaminate air,
ground water, and soil (there are no persistent surface water bodies in the immediate
vicinity of the site other than the evaporation and collection ponds). These media could
potentially transport contaminants to humans or ecological receptors.
2.2.1 Air. Potential impacts to humans can occur through outdoor air or indoor
air. Particulate matter can be transported by winds away from the sources. Radon can
also be transported via air away from the sources. The air monitoring program at the
Homestake site attempts to quantify this pathway. Radon gas can migrate into homes and
other occupied buildings.
2.2.2 Soil. Though the interim covers on the tailings piles can prevent direct
exposure to source contamination, surficial soils around the site could be affected by
deposition of airborne particulates or application of contaminated ground water, such as
at the irrigated acreage. Deeper native soils could be (and have been) contaminated by
leaching of contaminants from sources such as the tailings piles. Any leakage from the
ponds could also contaminate deeper soils.
2.2.3. Groundwater. The ground water can and has transported site
contaminants away from the tailings piles and possibly from other sources at the site.
The ground water is also a medium that has been used by residents downgradient of the
site. Alternative water sources have been developed for the majority of affected
downgradient residents, however, there are still some private wells in use in the
downgradient areas.
2.3 Receptors. The primary receptors at the site are the residents in the nearby
subdivisions, workers at the Homestake site, commercial workers in the vicinity, visitors,
and trespassers. Figure 2 summarizes the conceptual site model.
Final 12/23/10
-------
Figure 2. Conceptual Site Model (CSM) Summary
Homestake Mining Company (Grants) Superfund Site
Primary Secondary Release Transport
Sources Sources Mechanism Pathway
Radon Emanation
i •
Flushing
Notes:
o
' 1
Large
Tailings
Pile
Small
Tailings
Pile
Buried
Mill
Debris
Leaching
Reaching,
1
1
-J -*
1 ^
1
1
1
1
1
1
1
J
Leaching
t
Evaporation Sprayers
Ponds i
1
' Leaking
v T
Ground Overspray Deposition
Water
Complete Pathway
Incomplete Pathway
t
1 Leaching of Surface Soil ^
l_ Q,,iH
b cr
Irrigation
Runoff
i
r
ir
r
face
)il
r
1
1
1
1
Surface
Water
. Drinking
Water
Exposure
Route
Aerosols - Radon
Inhalation
Resuspended
Dust Inhalation
Ingestion
External Radiation
" Crops/Livestock
Ingestion
Ingestion
Potential
Receptors
Trespasser
Current
Future
Resident
Current
Future
Site
Worker
Current
Future
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
0
0
0
0
0
0
0
0
0
0
•
•
0
•
Release Mechanism
Potential Release Mechanism
Final 12/23/10
Page 10
-------
ADEQUACY OF PLUME CONTROL
3.1 Hydraulic Capture. The performance of the ground water extraction and
injection system in the alluvial aquifer was evaluated by the assessment of ground water
levels, concentration trends, and estimates of ground water flux. Hydraulic capture of the
contaminant plumes in the alluvial aquifer was evaluated by independently plotting and
hand-contouring water levels measured in March-April and June-July 2009. These
contours suggest a significant capture of water emanating from the large tailings pile,
particularly in the deeper incised alluvial channel along the southwestern end of the large
tailings pile. Capture is not as obvious in the contours near the small tailings pile in the
March-April contours. The contouring is somewhat limited by the available water levels
as only a limited subset of wells appear to be measured. Based on the drawn contours,
uncaptured flow lines may bypass injection and extraction at the northwest corner of the
large tailings pile.
Capture is not apparent for the irrigation pumping in the downgradient portions of the
uranium and selenium plumes, nor is it clear from available data that capture of the plume
along Highway 605 east of the site is maintained.
3.2 Concentration Trends. Concentration trends were independently plotted and
assessed as an indication of contaminant migration and progress toward clean-up.
Ground water concentrations of uranium and selenium in the alluvial aquifer in the
vicinity of the small tailings pile have been significantly reduced (such as well X, a
compliance point), though some wells have persistent concentrations well above the
cleanup goals as represented by the plot of uranium for well K4. Some wells that have
shown declines may be impacted by nearby injection of relatively clean water, including
well X. This would make it difficult for this well to detect leakage from the ponds.
Figure 3. Well X Uranium Concentration Trends.
Well X Uranium
E
Q.
Q.
-Well X Uranium
0.001 J
3/8/71
11/14/84 7/24/98
Date
4/1/12
11
Final 12/23/10
-------
Figure 4. Well K4 Uranium Concentration Trends.
K4 Uranium
100
10 -
E
Q.
Q.
0.1
K4 Uranium
1/31/9310/28/957/24/984/19/01 1/14/0410/10/067/6/09 4/1/12
Concentrations in the alluvial aquifer near the southwestern edge of the large tailings
pile have also been reduced, such as at well ST, but some remain high, such as at well S2,
located downgradient of the extraction system, and at others, such as B4 between the pile
and the extraction wells, uranium concentrations have actually risen.
Well SI 1 is screened in the alluvial aquifer near the northwest corner of the large
tailings pile along the suspected flow path possibly outside the capture of the extraction
and injection system. This well shows an erratic but generally higher trend in uranium
and sulfate concentrations after 2004. It is not clear if the variability in concentration is
related to changes in the operation of the injection laterals in this area.
Figure 5. Well ST Uranium Concentration Trends.
ST Uranium
100
E
a 10
1
-ST Uranium
5/25/79
1/31/93
10/10/06
Date
12
Final 12/23/10
-------
Figure 6. Well S2 Uranium Concentration Trends.
S2 Uranium
•S2 Uranium
5/25/1979
5/7/1990
4/19/2001
4/1/2012
Date
Figure 7. Well B4 Uranium Concentration Trends.
B4 Uranium
•B4..
1/31/93
7/24/98
1/14/04
7/6/09
Date
Figure 8. Well Sll Uranium Concentration Trends.
S11 Uranium
10
0.1
0.01
•S11 Uranium
1/31/93
7/24/98
1/14/04
7/6/09
Final 12/23/10
13
-------
Figure 9. Well Sll Sulfate Concentration Trends.
S1 1 Sulfate
cnnn -
4500 -
.4000 -
§3500 -
Snnn
^000 -
ijscnn -
=1000 -
W500 -
0 -
A
T
/
/
/
/
/
A /
A /
^> + < > *^—'*\ 1
• ^ ^^^v
1 '
— »-S11 Sulfate
1/31/93 7/24/98 1/14/04 7/6/09
Date
The concentrations in the downgradient portions of the uranium and selenium plumes
have generally been reduced (e.g., Wells 0654 and 0864, downgradient of the irrigation
pumping used to capture the plume), but well 0882, located south of the wells used for
irrigation in the northern plume, has shown an increase in concentration. This suggests
that the capture may not be complete.
Figure 10. Well 0654 Uranium Concentration Trends.
0654 Uranium
Ot. -,
OAC. H
En A -
oc\ ^t;
°- n i
on oc,
•— n 9 -
_ u.^
SO 15 -
"~ n -i
^ U.I -
n nt;
0.
A
*— » /\
*\y \ .
V M
\
\ **
\ *\ Jk t A
\s \^
W
• 0654 Uranium
7/24/98 4/19/01 1/14/04 10/10/06 7/6/09 4/1/12
Date
14
Final 12/23/10
-------
Figure 11. Well 0864 Uranium Concentration Trends.
0864 Uranium Dissolved
•Uranium
7/24/98
9/1/02
10/10/06
11/18/10
Figure 12. Well 0882 Uranium Concentration Trends.
0882 Uranium
0 (•)•?£; _
0.03 -
Ono^
a. 0.02 -
QQ 015 -
D n m
0.005 -
. A
/-*
A»—^^— •"^
^«V\f^
f-* ¥
—•—0882 Uranium
1/31/93 7/24/98 1/14/04 7/6/09 12/27/14
Date
The evaluation also included a survey of background ground water quality upgradient
of the large tailings pile. Though some of the far upgradient wells do show significant
impacts from uranium, upgradient wells closer to the site have shown only more subtle
increases, including wells PI, P2, and DD (shown for illustration). Higher concentrations
(above the 0.160 alluvial standard) appear to be found in wells on the western edge of the
San Mateo alluvial valley, including well DD. These may be related to the increasing
trend in uranium concentrations in well SI 1 downgradient and apparently along a flow
path from well DD. This illustrated the need to consider background concentrations of
uranium in assessing site strategies for the alluvial aquifer.
15
Final 12/23/10
-------
Figure 13. Well DP Uranium Concentration Trends.
Well DD Uranium
•Uranium
12/2/73
8/11/87
4/19/01
12/27/14
3.3 Groundwater Flux. There are concerns regarding the performance of the
alluvial ground water extraction and injection system arising from the assessment of the
mass flux through the system. The introduction of substantial amounts of water from
deeper aquifers into the alluvial aquifer suggests that, to some degree, concentration
declines may be due to dilution, rather than removal of contaminant mass. The
substantial addition of water in the vicinity of the tailings piles and difficulty in assessing
where the water is exactly being added makes the determination of the capture of the flux
of alluvial aquifer water flowing under the piles uncertain. As stated above, displacement
of some of the contaminated alluvial ground water flow to the west and, to a lesser extent,
east of the piles is possible.
3.4 Ground-Water Modeling. The report (Hydro-Engineering, 2006) on the
development of the current ground water flow and transport model was qualitatively
reviewed, with the intent of assessing the use of the model as a predictive tool and a
means to further verify extraction and injection system performance. Though there was
limited information on calibration statistics and the residuals at individual calibration
targets, the report does present comparisons of observed and predicted piezometric
contours and contaminant concentrations. There seemed to be reasonable agreement
between the observed and simulated values. It appears that the flow (MODFLOW) and
ground water transport (MT3DMS) modeling was conducted in accordance with normal
industry practice.
The primary concern with the modeling conducted for the site is the simulation of the
seepage of contaminated water from the large tailings pile. From the available
information on this step in the modeling process, it appears the modeling did not account
for the heterogeneity and preferred pathways for water injected into the tailings. It is
very probable that the flux of water is not uniform through the pile and that large volumes
of the pile still have a significant amount of their original pore fluids. The model likely
over-predicts the performance of tailings flushing.
16
Final 12/23/10
-------
3.5 Chinle Aquifer Contaminant Control. The performance of the extraction
and injection system to address the contamination in the Chinle aquifers was assessed by
the qualitative review of the information presented in the 2008 Annual Report for the site.
Performance for the extraction system in the Upper Chinle aquifer appears to be adequate
for containing the predominant contaminants. The ground water conditions in the Middle
Chinle aquifer are problematic. The ground water elevations are spatially quite variable
and do not make hydrologic sense. Based on the observed contours (October, 2008), it is
not clear that uranium in this aquifer is being adequately controlled by pumping from the
Middle Chinle.
3.6 Impacts to the San Andres Aquifer. A review of water quality data and
water levels for the relatively few wells screened in the San Andres Formation was
conducted. Though few data were available, there was no evidence of contaminant
impacts to these wells. Water levels were reasonably consistent and indicated a ground
water flow direction in the San Andres toward the northeast in March 2009. Flow
directions observed in 2008 and reported in the 2008 Annual Report were more easterly
to east-southeasterly. The well replaced by well 0806R should be properly
decommissioned in accordance with State requirements as soon as possible if not already
completed.
17
Final 12/23/10
-------
4 OVERALL REMEDIAL STRATEGY
The overall remedial strategy being implemented by Homestake is to flush the highly
contaminated pore fluids from the large tailings pile (to concentrations less than 2 ppm
uranium) and to capture the seepage and contaminated alluvial aquifer ground water near
the southern edge of the tailings piles. The extraction is coupled with downgradient
injection of water to assist in creating a hydraulic barrier. Subsidiary extraction and
injection occurs along State Highway 605 and in the downgradient portions of the
northern and southern alluvial ground water plumes. Additional extraction and injection
occurs in the Chinle aquifers to control the plumes and to restore aquifer quality.
According to Homestake, flushing of the tailings pile will be completed by 2012, with the
remediation of the ground water contamination completed by 2017.
This strategy has been evaluated regarding the likelihood of attaining its milestones
by the planned dates, the adequacy of the protection of human health and the
environment, and the cost-effectiveness of the work. The current strategy is generally
overly complex and at least partially depends on dilution to attain its goals. Alternatives
to the current strategy are broadly described and potentially applicable replacement
technologies are discussed below.
4.1 Flushing of Large Tailings Pile. The flushing of the large tailings pile with
fresh water largely derived from the Chinle aquifers is unlikely to truly achieve its
objective. Though the average concentration in recovered water from the toe drains and
sumps, and concentrations in wells penetrating the tailings has declined significantly, the
heterogeneity of the materials has prevented uniform flushing of the pore fluids. The
highly variable concentrations observed over relatively short distances in the tailings
would argue for such heterogeneity (as shown in Figure 14). Furthermore, the nature of
the wells in the tailings complicates the interpretation of the results. Most of the wells
that have been sampled have long screened intervals (most over 70 feet) and the wells
extend to depths below the tailings themselves. The likely occurrence of vertical
movement in the well from one permeable zone in the tailings to another, particularly if
injection was conducted in it at some point, makes it difficult to assess how
representative the samples are.
A review of the concentration trends for wells penetrating the tailings with reasonably
complete sampling histories was conducted. Though concentrations have generally
declined in the pile, a significant number of wells remain at high concentrations of
uranium without evidence of further declines. For example, concentrations in wells
WC1, WN4, EN4B dropped dramatically at the start of injection, but have not
significantly and consistently declined further as shown on the Figure 15.
It is probable the flushing program would not meet its goal by 2012, and in fact, the
need for ground water control would probably extend for many years past that date under
any scenario. Furthermore, the potential for rebound in concentrations once flushing
would cease should also be considered. In fact, it may be prudent to conduct a pilot test
in a portion of the tailings pile in the next few years to assess rebound potential. Even if
goals were to appear to be achieved, given the incomplete contact between injected water
18
Final 12/23/10
-------
and all tailings, and given the geochemical conditions that may allow slow leaching of
additional uranium out of the tailings solids, additional mass of uranium would ultimately
be available for leaching from the pile, contrary to the anticipated conditions under the
current strategy.
Figure 14. Uranium Concentrations in Large Tailings Pile
URANIUM 20-30 ng/L
LRANIUH 10-20 no
URANIUM 540 riQ/l
URANIUM 30-44
URANIUM 5-10 ng/l
USANIUM <5 r,g/T
TAILINGS URANIUM (mg/l)
2008
It is noted that as part of the current flushing program that the slimes present in the
LTP have apparently resulted in the flushing water becoming more reducing from the
organic matter in the slime. The data collected by HMC indicates that the selenium
concentrations have decreased significantly in the groundwater beneath the LTP
(Homestake 2009), presumably because of the more reduced geochemistry leading to
precipitation of selenium. There is the potential that if the flushing of the LTP was
stopped, the migration of groundwater through the LTP could gradually reoxidize the
groundwater and dissolution of the precipitated selenium and uranium could occur
(Wellman 2007).
Additional testing of oxidation-reduction potential would facilitate the analysis of the
fate and transport of the remaining contaminants in the pile. Such testing would entail
measurements of ORP, with pH, dissolved oxygen, and conductivity, downhole in wells
that have not been used recently for flushing. The data would be used to evaluate,
through geochemical modeling or comparison to appropriate Eh-pH diagrams, the
stability of uranium and selenium remaining in the pile, both where flushing occurred and
where there is little evidence of flushing influence.
The water recovered from the sumps around the tailings piles do not show dramatic
declines in uranium concentrations. Most have relatively stable or slightly decreasing
19
Final 12/23/10
-------
trends, though the N3 Sump has displayed a four-fold increase in a relatively short time.
These results suggest the flushing has had a limited effect in at least parts of the pile.
Representative concentration histories are provided in Figure 16.
Figure 15. Uranium Concentrations in Select Wells in a) Western Large Tailings Pile
and b) Eastern Large Tailings Pile.
Tailings Pile (West) Uranium
7D -,
/ u
fin
DU
cn
OU
E AC\
a4U
°-30 -
-^ OU
on
zu
4 r\
ID -
fc
/*^5$'\
/**V"vSJ\ A
1 ^2*flL'
+ vr ^rjap"
— WA3 Uranium
^WB2 Uranium
WC1 Uranium
-WC15 Uranium
— WD3 Uranium
— WE2 Uranium
— WN4 Uranium
1/31/93 7/24/98 1/14/04 7/6/09 12/27/14
Date
Tailings Wells (East) Uranium
1 on -,
1 nn
on
E 8°
Q- en -
D 40
on
0 -
*\ V-T^ A
^^*
— *— EC4 Uranium
• EE2 Uranium
EN4B Uranium
X EN4A Uranium
X T8 Uranium
10/28/957/24/984/19/01 1/14/0410/10/067/6/09 4/1/12
Date
Final 12/23/10
20
-------
Figure 16. Uranium Concentrations in Select Sumps: a) East 1 Sump, b) West 1
Sump, and c) N3 Sump
100 -
90 -
80 -
70 -
E 60 -
s- 5° -
°- 40 -
=> 30 -
20 -
10 -
0 -
10/2
70 -
60 -
50 -
1,40 -
°- 30 -
D 20
10 -
0 -
10/2
a) East 1 Sump Uranium
4
*+•*
* * *****
+ ** ^ * * *_*
* * *
^East 1 Sump
8/95 7/24/98 4/19/01 1/14/04 10/10/06 7/6/09 4/1/12
Date
b) West 1 Sump Uranium
A • A A. A.
* *^*** %«
A ^ ** A
+ W * «»
*West 1 Sump
8/95 7/24/98 4/19/01 1/14/04 10/10/06 7/6/09 4/1/12
Date
c) N3 Sump Uranium
•^n _
O^ - -
on
£ 1-s
Q. 15
a.
—i in - -
n
^^*
^__^~~~^^
^^^^^^^^
JP
./_
z
-*— N3 Sump Uranium
10/10/06 4/28/07 11/14/07 6/1/08 12/18/08 7/6/09
Date
21
Final 12/23/10
-------
As another line of evidence, the total volume of injected water was compared to an
estimate of the total pore space in the large tailings pile. Assuming approximately 200
gpm of clean water was injected into the pile for the 8 years since 2001 (up to the most
recent sampling data), approximately 840,000,000 gallons, or 110,000,000 cu ft, of water
have been introduced. Assuming a tailings volume of 800,000,000 cu ft and a porosity of
30%, there is about 240,000,000 cu ft of pore space. Based on this, assuming perfectly
uniform flushing by injected water (unlikely), only about half of the water that would
have been present has been flushed. Note that this doesn't account for the volume of
contaminated soils below the tailings but within the screened intervals of the wells, or the
increase in water storage in the pile since flushing began.
Finally, the addition of such a large quantity of water into the tailings increases the
amount of water that must be recovered from the alluvial aquifer and treated and/or
evaporated. If the injection was to stop, and seepage was allowed to occur from the
tailings, the flow of tailings water into the alluvial aquifer would slow significantly with
time. This would reduce the pumping needed to capture water to a rate that essentially
matches only what was naturally flowing under the tailings and whatever seepage was
occurring. Assuming a reasonably conservative hydraulic conductivity of 80 ft/day, a
natural gradient in the alluvial aquifer of 0.008, a width of 4500 feet and an average
saturated thickness of approximately 30 feet (with variations from 0 to over 50 feet), a
natural flow of 86,000 cu ft/day or about 450 gpm or less would have to be captured. In
addition, the seepage from the tailings would also have to be captured. Though initially
the flow would be relatively high, it would decline over time as the head in the pile would
drop. Note that the drainage of the tailings may take decades. The concentrations of
liquids recovered from the tailings may increase following cessation of flushing. Though
some of the recovered liquids would be best discharged directly into the evaporation
ponds, it is anticipated that a larger proportion of water would be treated by RO than is
currently the case, maximizing the capacity of the existing ponds. It is recommended that
this simplification to the remedy be implemented.
4.2 Downgradient Extraction and Injection. Though useful for assisting in
creating downgradient hydraulic barriers, injection of relatively clean water from other
aquifers into the alluvial aquifer downgradient of the site at rates that exceed extraction
complicates the control of the plumes and may do more to dilute the plume rather than
treat it. It is recommended that extraction be conducted at a rate necessary to capture the
three-dimensional extent of the existing plumes. Near the treatment plant, treated water
would be available for injection. If used, injection into the alluvial aquifer should be
located to minimize recirculation of water to the extraction wells. This treated water
would perhaps be best used to reverse the hydraulic gradient from the alluvial aquifer
toward the Upper Chinle aquifer by injection into the Upper Chinle. Current practice of
extraction from the Upper Chinle draws water downward from the more contaminated
alluvial aquifer, perpetuating the need for pumping. Though injection into the Chinle is
currently done, the injection could be increased in a step-wise fashion driving the
contaminants back toward the subcrops of the Upper Chinle at the base of the alluvial
aquifer. Care would have to be taken to prevent spread of contamination in the Upper
Chinle. Additional monitoring points may be needed and vigilant monitoring during the
implementation of the injection will be required.
22
Final 12/23/10
-------
Pumping of water from the northern and southern downgradient uranium and
selenium plumes would continue, but without injection of water from other aquifers into
the alluvial aquifer. The water pumped from these portions of the alluvial aquifer would
either be used directly for irrigation or treated for irrigation or re-injection (see section 8,
below). The extraction would be best done where it is now, at the narrow portions of the
saturated incised channels of the alluvial aquifers, near the 0.16 mg/L uranium contour
and upgradient of the confluences of the San Mateo alluvium and the Rio San Jose
alluvium. Contamination downgradient of these points would be allowed to naturally
attenuate due to dispersion and sorption to iron oxyhydroxides and clays. Based on the
presumed oxidized condition and low organic carbon content of the alluvial aquifer, other
attenuation processes are unlikely to be significant.
The conditions in the Middle Chinle require additional study to assess the
circumstances surrounding the unusual water levels in wells in the Middle Chinle and the
true ground water flow directions, especially in areas where concentrations exceed clean-
up goals. These studies may include examination of hydrographs, verification of top of
casing elevations, checking transcription errors, and possibly installing new wells.
Extraction of additional water, particularly in the vicinity of the Felice Acres subdivision
may be necessary.
4.3 Evaporative Concentration of Salts and Final Entombment of Wastes.
The current end point for wastes generated by the ground water extraction system is
either evaporative concentration of salts in the on-site ponds, or as accumulated salts in
the soils of the irrigated acreage. The use of untreated water for irrigation and the fate of
the accumulated contaminants in soils as a result are addressed in section 8. Unless the
decision is made to remove all wastes from the site (discussed further in section 4.4
below), the strategy of on-site management is reasonable. The salts accumulating in the
evaporation ponds may have some economic value at some time in the future. If not, the
dewatering and capping of the ponds at some time in the future would be consistent with
the current strategy of managing wastes on-site under the long-term stewardship of the
Department of Energy. The combination of a highly effective cap with the existing liner
under the pond wastes will provide added assurance of the isolation of the waste.
The integrity of the liner under the collection ponds was assessed through the
qualitative analysis of water levels and contaminant concentrations in adjacent alluvial
aquifer monitoring wells. The water levels observed in the wells were compared to the
variations in water levels in the ponds to glean evidence for leakage. (Note that the post-
2006 values in the database for the top of casing elevation for some of the C series wells
are apparently in error by almost 100 feet). A signal similar to the seasonal variations in
the pond water levels or a long-term rise in water levels following initial use of the ponds
in the mid-1990s would suggest possible leakage. The ground water concentrations in
the same wells were also analyzed for evidence for increases in solutes or contaminants
that would suggest brine leakage from the pond. The analysis was complicated by the
significant extraction and injection activities conducted under the ponds. No obvious
evidence was found for leaks in the evaporation ponds. Inspection of the liners should
continue with emphasis on those sections that are periodically exposed to sunlight.
23
Final 12/23/10
-------
Additional geophysical monitoring, such as downhole and/or cross-hole electrical
conductivity measurement or tomography, could give an indication of the leakage of
highly conductive brine.
Figure 17. Water Levels in Evaporation Ponds and Nearby Wells
Evap Pond 1
Evap Pond 2
WellC11
Well C9
Well C1
Well C2
6480
10/28/95 12/6/99
4/1/12
Figure 18. Water Levels in Evaporation Ponds and Other Nearby Wells
6600
6480
31-Jan- 28-Oct- 24-Jul- 19-Apr- 14-Jan- 10-Oct- 06-Jul- 01-Apr-
93 95 98 01 04 06 09 12
Date
24
Final 12/23/10
-------
Figure 19. Well K4 Sulfate Concentrations
K4 Sulfate
3500
-3000
o2500
£2000 -
151500 -
51000
w 500
0
•K4 Sulfate
6/15/94
7/24/98
9/1/02
Date
10/10/06
11/18/10
Figure 20. Well KZ Sulfate Concentrations.
KZ Sulfate
•KZ Sulfate
1/31/93
10/10/06
Date
4.4 Alternative Strategies. A number of alternatives to the current ground water
extraction and injection strategy were considered. These included passive treatment
options such as a permeable reactive (zero-valent iron) wall and polyphosphate treatment;
isolation technologies including a fully encompassing slurry wall; and full removal of the
tailings and placement of the waste in an engineered landfill created for this waste at an
unknown location within 30 miles of the site.
4.4.1 Slurry Wall. There are a number of sites, both for mine wastes (e.g., a
copper mine in Arizona) and for Superfund Sites (e.g., 9th Avenue Dump, Gary IN; Lipari
Landfill, Glassboro, NJ) where slurry walls have been used to isolate waste from the
surrounding aquifer and environment. A slurry wall around the large tailings pile at the
Homestake site would reduce the quantity of ground water requiring extraction and
treatment by reducing flux of ground water under the tailings pile. This would
potentially reduce the long-term costs for the operations, possibly significantly. The
installation of such a slurry wall through the entire alluvial aquifer is technically
25
Final 12/23/10
-------
implementable with current long-reach excavators, though sections of the wall in the
deepest portion of the incised buried channel in the southwestern part of the wall
alignment would require excavation by clamshell. Such a wall would require little
maintenance, but water levels on either side of the wall would need to be measured and
assessed to assure that the head difference across the wall would not be so great as to
fracture the wall. A rough cost estimate was prepared for such a slurry wall and is
presented in the table below. The estimated cost is approximately $15,000,000 before
contingencies. The subcrop of the Upper Chinle aquifer under the wall alignment would
pose a performance risk, as there would be a potential for contamination to bypass the
wall via the Upper Chinle sandstone. This risk could be addressed through increased
pumping near the subcrop, though this would reduce the operational cost savings.
Additional study of this alternative is recommended.
Table 1
Section
North
NE
East
SE
South
SW
West
NW
Homestake Mine Slurry Wall Construction Estimate 1/27/10
Length (ft.)
3800
400
1700
700
3400
800
1600
600
Mobilization/Demobilization
Equipment Setup
Avg. Depth
(ft.)
80
70
60
40
85
120
95
70
$/SF
$10.35
$10.35
$10.35
$9.25
$12.50
$14.75
$12.50
$10.35
Subtotal
Clay Cap on Top of Slurry Trench (1 3,000 LF X $
59.50/LF)
QC Testing/Final Report (1 ,041 ,000 SF X $0.40)
Submittals/Reports
Subtotal
Total Slurry Wall:
Excavate/Backfill
Cost
$3,146,400.00
$289,800.00
$1,055,700.00
$259,000.00
$3,612,500.00
$1,416,000.00
$1,900,000.00
$434,700.00
$14,014,100.00
$100,000
$50,000.00
$773,500.00
$416,400.00
$8,000.00
$1,347,900.00
$15,362,000.00
Assumes normal digging, no rocks, boulders or obstructions. No remote mixing.
Assumes 30 inch wide slurry wall
(RECON $/SF)
(RECON $/SF)
(RECON $/SF)
(RECON $/SF)
(RECON $/SF)
(RECON $/SF)
(RECON $/SF)
(RECON $/SF)
(RECON)
(RECON)
(RECON)
(RECON)
(RECON)
4.4.2 Permeable Reactive Barrier. Another alternative to remediating the
uranium and other redox-sensitive contaminants in the groundwater that was considered
is a permeable reactive barrier. Permeable reactive barriers (PRBs) passively treat
contaminated groundwater through removal of contaminants as the groundwater flows
through the reactive material that is placed in the barrier (SERDP 2000).
PRBs have been applied to uranium removal with different reactive materials.
Granular zero-valent iron (ZVI) is the most common reactive material that is used
(SERDP 2000); this was assumed to be the reactive material for the conceptual model for
Homestake. The basic mechanism for uranium removal with ZVI is reduction of the
26
Final 12/23/10
-------
uranium, which makes the uranium more insoluble, resulting in precipitation of the
uranium.
Different configurations of PRBs can be utilized. The two most common are
continuous reactive barriers (entire barrier contains the reactive material) and a funnel-
and-gate configuration, where impermeable outer walls "funnel" the contaminated
groundwater into the "gate", which is the barrier with the reactive material. The latter is
commonly used when a large groundwater plume needs to be remediated. As the size of
the groundwater plume to be remediated at the Homestake site is large, this configuration
was chosen for development of the conceptual design at Homestake.
Table 2 presents the calculations related to the PRB conceptual design and cost. A
thickness of three feet was chosen based on the thickness of the wall used for treating
uranium at Frye Canyon, Utah [EPA and USGS 2000]. The depth of the PRB is variable
depending on the depth to tie into the Chinle Formation. This depth varied between 85
and 120 feet as shown in Table 2.
The cost of the gate portion of the PRB was estimated using cost information from
the Federal Remediation Technology Roundtable (FRTR) Remediation Technologies
Screening Matrix and Reference Guide, Version 4.0, 4.40 Passive/Reactive Treatment
Walls (http://www.frtr.gov/scrntools.htm). Using the volume of reactive material in the
gate, the resulting gate cost estimate is approximately $19,000,000 before contingencies.
Note that the estimate is only the capital cost of the wall and does not include
monitoring and maintenance costs. It is expected that the PRB would continue to operate
as long as the uranium concentrations upgradient of the wall remain above the clean up
goal of 0.16 mg/L for the alluvial aquifer. This would likely require decades. Given the
long operating life, the potential for deposition of minerals from the relatively high TDS
would need to be considered. An estimate of the potential for mineral deposition can be
obtained from data from the Denver Federal Center PRB. At that site, with a TDS of
1200 ppm, a surface permeability loss up to 14% was observed after four years operation
(FRTR 2002). As the TDS in the alluvial aquifer is approximately 2500 ppm, with some
TDS concentrations near the tailings piles up to 20,000 ppm (Homestake, 2009), there is
the potential that the ZVI would need to be rehabilitated or replaced periodically during
the life of the barrier.
As with the slurry wall option, there is a potential for migration of contaminants
through the Upper Chinle aquifer that subcrops under the large tailings pile. This may
require continued extraction and treatment of ground water. Because of the relatively
high capital cost, the significant potential recurring iron replacement costs, the long
remediation times, and the risk of flow past the PRB in the Upper Chinle, this technology
is not recommended for use at Homestake.
27
Final 12/23/10
-------
Table 2
Section
South
Funnel
SW Gate
West Funnel
Homestake Mine PRB Wall Construction Estimate
Length (ft.)
3500
800
2000
Mobilization/Demobilization
Equipment Setup
Avg.
Depth (ft.)
85
120
95
$/SF
$12.50
$127.50
$12.50
Subtotal
Clay Cap on Top of Slurry Trench (5500 LF X $
59.50/LF)
QC Testing/Final Report (583,500 SF X $0.40)
Submittals/Reports
Subtotal
Total PRB Wall:
Excavate/Backfill
Cost
$3,718,750.00
$12,240,000.00
$2,375,000.00
$18,333,750.00
$100,000
$50,000.00
$327,250.00
$233,400.00
$8,000.00
$718,650.00
$19,052,400.00
Notes
(RECON
(slurry wall) $/SF)
(FRTR
(iron filings) $/SF)
(RECON
(slurry wall) $/SF)
(RECON)
(RECON)
(RECON)
(entire wall) (RECON)
(RECON)
Note: Estimate based on marked -up budget costs from RECON and FRTR w/ expected range of
accuracy +25% to -25%
Estimate assumes normal digging, no rocks, boulders or obstructions and no remote mixing.
Assumes 30 inch wide slurry wall funnel for south and west sections and 30 inch wide iron filled
gate for SW section
Assumes PRB gate filled with iron filings full depth
4.4.3 In-Situ Immobilization. In-situ immobilization, using an amendment to
reduce the mobility of the contaminants, was also evaluated. This technology was
evaluated in detail for the specific technology of polyphosphate immobilization of
uranium given the information available and success of application in a pilot study at the
Hanford facility in Eastern Washington (Wellman, et al, 2007) in treating uranium in
groundwater. In this technology, uranium in the aquifer is sequestered through reaction of
phosphate with uranium to form relatively insoluble and stable uranyl phosphate
minerals. The use of polyphosphate (polymerized phosphate) allows reduction of the rate
of reaction of the phosphate with the uranium and other metals in groundwater,
increasing the potential for wider distribution of the amendment in the aquifer and
decreasing the potential for injection well clogging. Though the concept was assessed for
treatment of the materials below the tailings, a similar concept could be applied to the
tailings themselves. The considerations discussed below would generally apply to the
tailings.
Hydrogeological and geochemical information was supplied to the Hanford team for
assessment of application of the polyphosphate immobilization technology to Homestake.
The information (largely derived from 2006 CAP report and the Homestake site database)
included the following:
28
Final 12/23/10
-------
- Subsurface materials - a heterogeneous mix of silt, sand, and gravel.
- Hydraulic conductivities of 30-100 ft/day, but varies 1-800 ft/day,
- Ground water chemistry and contaminant data: Primary cation is sodium
(3000-4000 ppm vs 10-20 ppm total for Ca, Mg, K). Anions split
between sulfate (3000-5000 ppm), bicarbonate (2000-4000 ppm),
carbonate (600-1600 ppm), and chloride (250-1000 ppm). pH values are
9.5-10. Redox is slightly negative but limited data. Uranium
concentrations 2-12 ppm (possibly higher), and selenium 0.3-3 ppm.
It was determined through discussions with the Hanford team that the conditions at
Homestake were significantly different from those at Hanford. The pH is slightly alkaline
at Hanford but strongly alkaline at Homestake, and there is a much larger range of
hydraulic conductivity at Homestake compared to that at Hanford. The former potentially
results in the formation of different uranyl-phosphate species and the latter affects the
amount of polymerization of the polyphosphate, thus the retardation of the phosphate-
uranium reaction rate, used in the application. It was the conclusion of the Hanford team
that these differences would require substantial lab and pilot scale testing for determining
the application of the technology to Homestake. It is estimated that these technology
application activities would cost at least $5 million.
Assuming that the polyphosphate technology could be tailored to Homestake, the
following field scenarios were prepared:
- Alternative 1 - Treat under entire pile. A 70 feet depth on average and
an area of 8,000,000 sq ft under the tailings pile was assumed as needing
treatment, resulting in 560 million cu ft or ~ 21 million cu yd.
- Alternative 2 - Treat under the pile in perched water zone. This would
be roughly 4/7ths of the volume of alternative 1 (40 feet of the 70 foot
depth is above the water table) or 12 million cu yd.
- Alternative 3 - Create a horseshoe-shaped treatment zone below the
water table around the pile, including 10 feet of soil above the water
table. A 50-foot width was assumed for the barrier along 2/3 of the
perimeter (12,000 feet) on the downgradient and side gradient edges of
the pile, or a total 18,000,000 cu ft (670,000 cu yds). The vertical 10-
foot-thick barrier just above the water table, which would inhibit mass
loading on the water table would be l/7th of the Alternative 1 total, or
3,000,000 cu yds, for a total of approximately 3.7 million cu yd.
Costs for Alternatives 2 and 3 were then estimated using information from Hanford
and typical drilling costs. For costing Alternative 2, vertical well spacing of 25 ft was
assumed in lines perpendicular to ground water flow separated by 250 feet, resulting in
14 lines with a total of 2570 wells, on average 110 feet deep or 280,000 feet of drilling.
For Alternative 3, 6400 linear feet was assumed with 10 feet spacing, resulting in 640
wells at an average depth of 70 feet for a total of-45,000 feet of drilling. Assuming costs
29
Final 12/23/10
-------
of $60/foot for Alternative 2 and $50/foot for Alternative 3 (easier access than
Alternative 2), costs of $16,800,000 and $2,300,000 for drilling and well installation
were obtained, respectively, for Alternatives 2 and 3. It is noted that these costs do not
include oversight, field geologist for logging, contingencies, etc.
An estimate of the cost of the materials was supplied by Hanford for each alternative.
This assumed an approximate material cost of $30,000-$35,000/well. The resultant
material costs were -$32,000,000 and $8,000,000, respectively, for Alternatives 2 and 3.
It is noted that these costs are for materials only and do not include material injection.
The total estimated costs for Alternatives 2 and 3 were then approximately
$54,000,000 and $16,000,000. These costs are considered minimum costs as they do not
include material injection and drilling documentation costs, as well as any cost
contingencies.
It is noted that there are other in-situ immobilization technologies. These are
mentioned briefly here. One group includes technologies that create reducing conditions,
which can also immobilize uranium and selenium. There is evidence from the decreases
in contaminants, particularly selenium (HMC, 2009a), that this is occurring with the
current flushing program. It is hypothesized (HMC, 2009b) that the water injected for
flushing may be coming into contact with organic matter in the slime present in the
tailings deposited in the LTP. Flushing through the slime may have caused the flushing
water to become more reducing [limited HMC geochemical data indicates this may be
occurring (HMC, 2009b)]. The reducing conditions could then be carried down with the
flushing water into the water retained in the LTP and the groundwater beneath the LTP.
Precipitation of the uranium and selenium related to the more reducing conditions may
then have resulted in reduction of the dissolved phase uranium and selenium
concentrations.
The drawback of the technologies based on immobilization through creation of
reducing conditions is the potential release of sequestered uranium and selenium if the
reducing conditions become more oxidizing in the future, thus bringing into question the
long-term effectiveness of the technology (Wellman et al., 2007). Two scenarios where
this release may occur at Homestake are 1) flushing is discontinued and more oxidizing
groundwater would travel through the aquifer below the LTP, and 2) as flushing is
continued, the reducing effect of the slime may be lessened over time, with the flushing
water, therefore the water in and below the LTP, becoming more oxidized.
The polyphosphate sequestration technology creates minerals that are stable under
oxidizing conditions, therefore, has higher potential long-term effectiveness under a fuller
range of aquifer conditions. There is also a relatively new immobilization technology that
is still in lab development (Fryxell et al., 2005). The drawback of the latter is the lack of
field application and the associated lab and pilot scale effort that would be needed to
determine if this technology was appropriate for use at Homestake. Because of these
drawbacks, these technologies are referenced but not described in detail in this report.
Recently, HMC (HMC, 201 Ob) has proposed the performance of two field pilots that
are exploring the removal of uranium in-situ through adsorption or by in-situ
precipitation. The first field pilot is to test the removal of uranium from groundwater
30
Final 12/23/10
-------
through adsorption onto zeolite. The second field pilot is to test the removal of uranium
from groundwater through the addition of amendments to induce in-situ precipitation of
low solubility uranium phosphates or oxide. .
4.4.4 Removal of Tailings. The Department of Energy (DOE) is currently in the
process of excavating, transporting, and disposing of the Moab uranium mill tailings site
in Grand County, Utah. The DOE has designed and built a new disposal cell in Crescent
Junction, Utah, 30 miles from the Moab site. The amount of waste to be relocated to the
new site has been estimated to be approximately 12,000,000 cubic yards. The Moab
transportation will be completed using trucks and/or rail. The project is expected to be
completed in 2019 with a current total completion cost estimate range of $844,200,000 to
$1,084,200,000. These projected volumes and costs were used to develop a rough
estimate of performing a similar relocation at the Homestake Mining Company Site. A
scaling factor in $ per cubic yard was calculated using the lower end of the DOE estimate
to account for tasks that would be similar and not dependent on disposal volume, such as
cell design costs. For estimating purposes, it is assumed that all impacted material would
be excavated and relocated to a new cell located a similar distance from the HMC site.
By removing material from the site to levels that would satisfy the unrestricted release
criteria in 10 CFR 40, the site would not require long-term stewardship. The significantly
greater estimated volume of tailings, contaminated soil, and buried debris at the HMC
site leads to a significantly higher estimated cost estimate than is currently in place for
Moab. The cost of any long-term groundwater treatment that may be needed following
the removal of the tailings has not been included in the estimate.
Table 3
Estimate for Removal of All Tailings/Waste and Off-Site
Disposal at a Newly Constructed 10 CFR 40 Compliant Cell
Area
LTP and Cover
Soils Beneath LTP
STP/EP
Mill Pits
In-situ Mass
(ton)
28,000,000
11,000,000
1,300,000
700,000
41,000,000
Excavated.
Volume (yd3)
26,000,000
10,000,000
1,500,000
800,000
38,000,000
Moab $/yd3
$70
$70
$70
$70
Total Cost
Estimated Relocation
Cost
$1,800,000,000
$700,000,000
$100,000,000
$56,000,000
$2,700,000,000
Volume assumptions are: minimal segregation of cover material; removal of
contaminated soil beneath the LTP; density of 1 .3 tons per cubic yard in-situ; an over
excavation factor of 25 percent for the STP and Mill areas; a volume expansion of 20
percent after excavation; and volumes and costs rounded to two significant digits.
Moab cost per cubic yard is estimated from the July 2009 Department of Energy, Office of
Environmental Management Report on Annual Funding Requirements, Moab Uranium
Mill Tailings Remedial Action Project.
The Department of Energy completed a Final Environmental Impact Statement
(FEIS) for the Remediation of the Moab Uranium Mill Tailings in July 2005. In
accordance with the National Environmental Policy Act, the FEIS considered the
unavoidable adverse impacts, the relationship between short-term uses and long-term
productivity, and the irreversible or irretrievable commitment of resources that would
Final 12/23/10
31
-------
occur if the off-site disposal alternative was implemented. A similar analysis would need
to be performed at the Homestake site. As part of the RSE Addendum work, the removal
of HMC materials was modeled in the AFCEE Sustainable Remediation Tool (SRT)
Version 2 (Jan. 2010). The SRT provides an estimate of the carbon dioxide emissions to
the atmosphere, the total energy consumed, and the safety/accident risk of completing the
soil excavation.
For the Large Tailings Pile removal, the SRT calculates that approximately 270,000
tons of carbon dioxide would be emitted during the project. Energy needs would be
large, equivalent to 1.0 billion kilowatt-hours (the power needed annually to run 96,000
homes). Because of the significant amount of construction and truck traffic needed to
move the HMC material, the predicted loss of work time, 6,600 hours due to an estimated
140 injuries is significant. Copies of the SRT worksheets are in Appendix C. Note that
using a rate of 1.5 fatalities per 100,000,000 miles driven (ITRC Remediation Risk
Management Technical Regulatory Guidance, in press) and a total of 150,000,000 miles
driven (assuming disposal 20 miles away), it is a strong possibility that there may be a
fatality during the project. There are other potential risks associated with the disruption
of the tailings pile, including an increase in radon and dust emissions, though engineering
controls can be applied to mitigate these impacts.
Note that tailings relocation would represent a large positive economic impact to the
Milan/Grants area, offering significant employment for a number of years. The
employment and project related spending would have ripple effects through the rest of
the local economy.
For comparison, the carbon loading, energy use, and accident risk for the current
ground water extraction and treatment system and for a slurry wall and associated
reduced pump and treat system have been calculated and are presented in Table 4. The
impacts of the relocation of the tailings pile significantly exceed the impacts of both the
current system and the slurry wall alternative. The current extraction and treatment
system would have to operate for approximately 150 years to equal the energy use and
carbon emission impacts of the tailings pile relocation (using trucks). The important (but
somewhat arbitrary) assumptions include:
• Current pump and treat system would operate with 95% up-time for 50 years
to control plume migration from the large tailing pile and requires 4 persons to
operate living 5 miles away
• A slurry wall would result in a 75% reduction in required pumping during the
first 25 years and an 88% reduction in required pumping for 25-75 years,
along with a reduction in staffing of 1 person compared to existing system
• Total electrical demand is dominated by an estimated 300 FTP for electric
motors (for pumps, sprayers, compressors, etc.) and motor efficiency is 80%
• Bentonite (for slurry wall) haul distance is 1000 miles from northeast
Wyoming to site (in the SRT, used mulch as surrogate for bentonite)
• Efficiency of electrical production is not considered (some references indicate
a production and transportation efficiency for electricity at 33%)
• Ground water monitoring impacts are not included
32
Final 12/23/10
-------
• Energy use in preparing a lined repository site for a relocated tailings pile was
not included
Table 4. Comparison
Current Remedial Ap
Technology
Current Ground Water
Extraction and
Treatment
Tailings and
Underlying Soil
Excavation and Off-
Site Disposal
Slurry Wall
Construction
Reduced Pumping
with Slurry Wall
of Energy Usage, Carbon Emissions, and Accident Risk for
proach and Alternative Remedies
Life-Cycle Energy Use*
(kW-hr)
360,000,000
1, 000, 000, 000
8,300,000
97,000,000
Total = 105,300,000
Life-Cycle Carbon
Emissions (tons)
81,000
270,000
35,000
21,000
Total = 56, 000
Estimated Number of
Lost-Time Accidents
0.4
140
16
0.46
Total = 16.46
* Life-cycle impacts for ground water extraction considers only operations, not construction
Based on suggestions from stakeholders, a simple analysis was conducted for the
alternative of transporting the excavated tailings to an engineered repository 20 miles
away via a slurry pipeline. A similar proposal was made to transport tailings from the
Moab site (Hochstein et al., 2003). Although the proposal was not accepted, the
computations for that project were roughly scaled to assess the energy usage for the
Homestake site relative to the transportation by truck.
The Moab proposal involved transport of an estimated 400 tons/hour over 80 miles.
The piping would include both a slurry pipeline and a water return line (to reduce use of
water). Over 2,000 gpm of water would be required, of which 1,500 gpm would be
returned. The Moab design included two pump stations each including three large (2100
HP) pumps capable of generating 2,800 psi, of which two would be active at any one
time. The design also included a 1200 HP return flow pump.
Assuming that the Homestake production rate would be similar (400 tons/hour) to the
Moab project, a make-up water flow of 500 gpm would be required. Given the shorter
distance, only one pump station with smaller pumps (1500 HP) was assumed to be
required for the Homestake project, and no pump was assumed to be required for the
return flow, which could be gravity-fed given the difference in elevation between the
assumed repository location and the Homestake site. Based on the estimate of mass in
the tailings piles at the Homestake site, it would take more than six years to move the
tailings. Assuming a 70% electrical efficiency (motor and pump), approximately 3200
kW would be required to run the pumps. For the duration of the project, over 180 million
kW-hrs of electricity would be required.
This is a large energy use but it is significantly less than the energy required for
trucking. Note that the SRT only provides the total diesel fuel consumed for both
33
Final 12/23/10
-------
excavation and transport. Since the fuel use for excavation would be approximately the
same for both trucking and slurry pipeline transport, the true comparison for transport
can't be made. The accident risk for workers would undoubtedly be significantly less
with the slurry transport. The potential environmental consequences of a pipeline break
with relatively liquid slurry would likely be more severe than for a truck carrying tailing
overturning along the haul route. The slurry system would result in the export of a
significant amount of ground water from the vicinity of the site.
The cost estimate for relocating the Moab tailings by slurry pipeline was
$122,000,000 in 2002 dollars. Based on a scaling of the capital and operating costs, as
summarized in Table 5, the cost for transporting and handling Homestake tailings via
slurry pipeline was estimated to be about $112,000,000. Note that this estimate has
uncertain accuracy as the validity of the costs presented in Hochstein et al. (2003) was
not evaluated.
Table 5. Cost Estimate for Slurry Transport of Homestake Tailings
Based on Hochstein et al., 2003 Paper on Moab Tailings Relocation by Slurry
Capital Costs
Item
Plant Prep
Pump Stations
Pipelines
Dewatering Plant
Control Systems
Indirects, Contingency
Total
Homestake Capital Cost
Inflation Factor (2002 to
2010)
Current Dollars
Operating Costs
Unit Cost from Hochstein
Mass at Homestake
Operating Costs-
Homestake
Inflation Factor (2002 to
2010)
Current Dollars
Total Estimated Cost
Hochstein et al.
2003 (Million $)
3
10.2
48.2
8.1
5.2
22.3
97
$43,760,375
1.21
$52,950,053.55
1.2
41,000,000
$49,200,000
1.21
$59,532,000
$112,482,054
Adjustment
for
Homestake
0
-5
-36
0
0
-12.2
-53.2
per ton
ton
Notes
Only one pump station
Only 20 miles instead of 80
Proportional to reduction
From
http://www.bls.gov/data/inflatio
n_calculator.htm
In 2010 dollars
Final 12/23/10
34
-------
4.4.5 Alternative Energy Potential at the Homestake Site. The site is located in
the portion of the US with the most available sunshine and relatively high solar power
density. According to a map from the Department of Energy
(http://www.nrel.gov/gis/images/map_pv_national_lo-res.jpg) , the site is in a region with
over 6000 W-hr/(sq m-day) photovoltaic solar resource. The placement of photovoltaic
panels at the site could generate some of the electricity required for operations at the
plant, or for sale. There are smaller regional transmission lines not too far north and
south of the site. Though the economics may or may not currently be favorable, the
opportunity exists to showcase the use of "green" energy at a contaminated site.
One drawback posed by the site would be the difficult geotechnical properties of the
tailings pile. The pile has undergone settlement, and if dewatered, additional settlement
would likely occur. This would likely adversely affect the orientation or even stability of
the panels. The foundation improvement that would likely be required would add
significantly to the cost. Placement of panels on other tracts of land around the piles
would be more feasible.
The site does not appear to offer adequate average wind speed to justify a large wind
turbine project (see
http://www.windpoweringamerica.gov/images/windmaps/nm_50m_800.jpg), but may
have adequate wind resource to power a few smaller generators for on-site use.
35
Final 12/23/10
-------
5 RECOMMENDED MODIFICATIONS TO THE EXISTING
TREATMENT PLANT
5.1 Evaluation Basis. The basis of the evaluation of the RO treatment process
was the flow rates and species concentrations estimated for the revised remedial strategy
discussed in section 4.1. These flow rates and concentrations were based on earlier
dewatering rates and observed sump concentrations. Comparison with the flow rate and
species concentrations currently used at HMC (Table 6) indicates that the feed species
concentrations proposed in are all comparable or lower than those currently in the feed
into the RO treatment plant. The feed rate, although higher, is still well below the average
yearly feed rate of 540 gpm as estimated as achievable by HMC (HMC, 2010a). This
indicates that the capability of the current treatment system to treat the feed under the
proposed alternative remedial strategy discussed in section 4 is not a constraint.
5.2 System Constraints. An apparent constraint on the capability of the current
treatment system, however, as indicated in section 6, is the capacity of the evaporation
ponds or other holding capacity to receive the waste brine from the RO treatment plant in
combination with other waste streams. As indicated in section 6, the evaporative capacity
of the current Pond system, assuming direct disposal of the highest concentration water
from the tailing piles and the estimated brine from treatment of the 450 gpm feed stream
proposed in section 4, is short by 20-40 gpm, assuming continued operation of the active
evaporation spraying. Modifications to the treatment system were then evaluated to first
address this shortfall.
5.3 Alternatives to Current Treatment Operation One approach to addressing
this shortfall is increasing the amount of treatment of the water collected downgradient of
the Tailings Pile that is currently directly conveyed to the evaporation ponds. This would
then allow more volume of brine from the RO treatment system to go the Ponds. HMC
has proposed and is currently developing the infrastructure for a pilot using the East
Collection Pond for mixing some of the collected water from Tailings Pile, which is rich
in calcium, with water pumped from the alluvial aquifer along the L line, which is rich in
bicarbonate. The hypothesis is that calcium carbonate (the bicarbonate reacting to form
carbonate) will precipitate out, with the now lower TDS water then being fed into the
clarifier and subsequent completion of the RO treatment process. HMC is proposing to
start with a 10 gpm flow rate in the pilot and then using increased flow rates as the
process is developed (HMC, 2010a).
Another approach to decreasing the capacity shortfall is to increase the RO product to
brine ratio. This is most simply accomplished with the existing RO system by adding an
additional high pressure stage(s). This is currently the configuration for the original two
stage RO unit, with the high pressure stage extracting approximately 16% more product
from the incoming feed by recirculating the brine from the low pressure stage through the
high pressure stage (the current high pressure unit produces approximately 40 gpm more
product based on a 250 gpm influent flow rate). The disadvantage of the higher pressure
36
Final 12/23/10
-------
is the increased electrical costs to run at the higher operating pressure so the higher
operating costs need to be weighed against the increased product output. Also, as the
current low pressure unit is newer than the original low/high pressure unit, the efficiency
in product to brine ratios may not be as high [the operating data from the 9-14-09 and 9-
22-09 logs suggests that the more recent low pressure RO unit has a higher product to
brine efficiency (HMC, 2009c)].
Another approach to meeting the capacity shortfall is other technologies that could
remove the uranium, selenium, and molybdenum with lower or no waste production. In
considering these technologies, it was assumed that pretreatment for TDS reduction
would be necessary as the average TDS and sulfate concentrations (5800 and 2900 mg/L,
respectively) in the feed are above the discharge standards for reinjection (alluvial aquifer
standards of 2734 and 1500 mg/L, respectively). It was therefore assumed that the feed
would go through the pretreatment part of the current RO treatment process but a portion
could be diverted to another treatment media.
The first alternative treatment media considered was ion exchange. Although the
same resin that designated as being highly selective for uranium for potential treatment of
the irrigation water (refer to section 8) was a candidate, the feed for the treatment plan,
unlike the irrigation water, also has selenium and molybdenum well above aquifer
standards. Although it is feasible to add an additional ion exchange column to remove the
molybdenum, no ion exchange resin was found that could reliably remove selenite
(SeO/f2 or HSeCV), which is one of the anionic forms of selenium that may be present in
the treatment plant feed. Therefore, this option was eliminated from further consideration.
The second alternative treatment media considered was zero valent iron (ZVI), which
has the potential to remove uranium, molybdenum, and selenium through precipitation by
inducing reducing conditions. It was assumed that the shortfall of 40 gal/min of flow
would be diverted after pretreatment of the feed. Using the design criteria for retention
from the Fry Canyon Site of a 3' thick wall with a 1.5 ft/day groundwater velocity, it was
calculated that costs of the ZVI material necessary for treating the 40 gpm shortfall would
be approximately $200,000, with an additional $100,000 estimated to pilot test, construct,
design, and install the column. This option was eliminated from further consideration
both because of the relatively high cost for the amount of additional product obtained and
because of concerns about the plant size allowing the amount of ZVI material (200 cu
yds) estimated as necessary for treatment.
In summary, the current treatment system appears to be capable of treating the feed
from both the current operations and the feed proposed as an alternative as a result of the
RSE Addendum effort; however, the treatment plant throughput is constrained because of
the limitations of the capacity for waste disposal. The two most implementable
approaches for optimizing the treatment system that would decrease the shortfall in waste
disposal capacity are 1) the treatment of the high TDS tailings water (currently being
pumped directly to the waste ponds), with a pretreatment salt precipitation in the East
Collection Pond before treatment in the treatment plant and 2) augmentation of the low
pressure only RO unit with a high pressure stage. These two approaches in combination
37
Final 12/23/10
-------
may meet the present shortfall in waste disposal capacity although actual decreases in
shortfall would need to be determined from pilot tests.
Although not directly related to optimization of the RO treatment system, the feed
rate proposed in Task 1 could also be achieved through increase in the waste disposal
capacity through Pond capacity expansion. The alternatives for Pond expansion, with
varying degrees of evaporation spraying, are discussed in detail in Section 6.
Table 6. Comparison of Average Flow Rates and Species
Concentrations for Current and Proposed Treatment Systems Feed
Feed HMC
Revised Feed
TDS (ppm)
5800
3600
U (mg/L)
13.4
6.7
Se (mg/L)
1.3
1.8
Molybdenum
(mg/L)
17.4
Flow rate
415
450
(avg late
Sept 2009)
38
Final 12/23/10
-------
6 EVAPORATION RATES AND NEED FOR ADDITIONAL
EVAPORATION CAPACITY
6.1 Estimate of Lake Evaporation Assuming Fresh Water. An estimate of the
annual lake evaporation rate for fresh water from the existing ponds was developed using
the procedure presented in Appendix D. Based on that analysis, a maximum 124
gallons/minute (annual average) could be evaporated. This does not account for the
salinity of the existing liquids in the pond.
6.2 Effect of Salinity. To estimate the reduction in evaporation rate because of
the brine, it was assumed that the water in the ponds was fully saturated brine. Using the
brine and fresh water plots from M. Al-Shammiri "Evaporation rate as a function of
water salinity," Desalination 150 (2202) 182-203, an approximate rate reduction of 50%
for brine compared to fresh water was obtained. This would suggest that an approximate
evaporation rate for the brine of 62 gpm. This compares to the passive rate of evaporation
measured by Homestake of approximately 80 gpm. It is noted that all these calculations
are an average over the year, with summer evaporation expected to be higher and winter
evaporation to be lower. It is also noted that evaporation rates vary between studies, as
well as the interpretation and application of results of the studies specifically to
Homestake. For example, Homestake has referenced the Salhotra et al. 1985 study as
indicating a reduction of 10% from fresh water to brine. The 50% rate from the Al-
Shammiri study, adjusted upwards by the factor of 80/62, is used in the remainder of this
discussion as an illustrative example but with the reservation that any sizing of ponds
would need to use field data directly collected from Homestake to accurately predict the
relationship between brine concentration, pond area, and evaporation rates.
6.3 Need for Additional Evaporative Capacity. Since 80 gpm is less than the
current flow rate into the ponds (-170 gpm), there appears to be a need for additional
measures beyond passive evaporation. It is anticipated that an average evaporative
capacity of 200 gpm is required (see Appendix D). The current operation is utilizing
evaporative spraying to augment the evaporation rates, with the combined passive and
augmented evaporation rates being approximately double the passive evaporation rates.
For the existing operating ponds, this results in an evaporation rate of 160 gpm.
Assuming evaporative spraying is continued at the same level as present, the shortfall of
40 gpm could be accomplished by expanding the existing pond capacity by
approximately 11 acres (see Appendix D).
If evaporation sprayers were used only on the new evaporation pond of 30 acres, (use
only of passive evaporation on Ponds 1 and 2), the evaporation rate is estimated to be 190
gpm, which is less than the 200 gpm flow rate. The calculations indicate a potential
need for approximately 36 acres surface area instead of the 30 acre surface area of the
pond currently being constructed (see Appendix D). It is noted, however, that only
surface evaporation, not additional pond volume, was assumed in calculating the brine
capacity for the third pond of 36 acres. Therefore, it is not expected that any immediate
shortfall of capacity will result if evaporative spraying was used only on the third pond
currently being constructed.
39
Final 12/23/10
-------
If evaporation sprayers were not used on any of the ponds, the estimated total
evaporation rate would be 135 gpm. Again assuming a flow rate of 200 gpm and capacity
from only passive evaporation from the three ponds, the additional capacity beyond the
two operating ponds was calculated to be 52 acres. This indicates the potential limitation
of brine capacity on the complete discontinuation of evaporative spraying.
In summary, these calculations suggest that additional evaporative capacity is
necessary for the proposed flow of 200 gpm if the current system or less spray
evaporation is used. If the current evaporation spraying level is continued on all ponds,
including the 30-acre third pond currently under construction, there appears to be
adequate long-term evaporative capacity. If spray evaporation was discontinued on Ponds
1 and 2, a slight evaporative undercapacity was predicted. However, this undercapacity
could be met by the increase in volumetric capacity from the third pond, which was not
taken into account in the calculations discussed here. Finally this analysis suggests that a
long-term pond evaporative undercapacity would result if spray evaporation was
discontinued on all ponds.
Another way to increase evaporative capacity is to optimize the current Turbomist
evaporation setup or equipment. A detailed evaluation of the different evaporation
augmentation equipment is beyond the scope of this RSE. However, it is recommended
that Homestake review and consider the information supplied by TASC. This
information, which includes an article comparing different types of evaporative sprayers,
additional facts on the Turbomist system, and several web addresses with information on
evaporative sprayers is included in Appendix E.
The USAGE recommends that for whatever option is adopted, including hybrids of
the example options above, the option be well developed with site specific and design
information to provide accurate predictions of the long-term evaporative capacity needs.
Also, the USAGE recommends that the size of the additional evaporation pond be based
on the amount of evaporative capacity as calculated from the actual mix of evaporation
and treatment equipment and operation that will be employed. This will ensure that the
evaporation capacity of the additional pond will be adequate to meet the long-term
evaporative capacity needs of the site.
40
Final 12/23/10
-------
7 GROUND WATER MONITORING NETWORK AND AIR
MONITORING PROGRAM
7.1 Groundwater Monitoring.
7.1.1 Environmental Monitoring Objectives. The rationale for collecting
samples from each well at the Homestake site is not clear (though some wells are
compliance points and are required to be sampled). Some samples may be collected to
support specific operational decisions for the extraction and injection systems, and these
needs may change year to year or even month to month. A more strategic approach to
monitoring may allow a significant streamlining to the monitoring program yet provide a
program more focused on the true objectives of the sampling. The primary reasons for
collecting samples at the site include:
- monitoring progress of the source reduction due to flushing of the large
tailings pile,
- monitoring of the containment of the alluvial aquifer plume emanating from
the tailings piles to assure capture,
- monitoring the containment of the downgradient uranium and selenium
plumes in the alluvial aquifer west and southwest of the site,
- monitoring of the concentrations and lateral and vertical extent of the
downgradient plumes in the alluvial aquifer to track the response of the
plumes to reductions in mass flux from the sources,
- verify the boundary between saturated and unsaturated alluvium
- monitoring of the capture and migration of the Chinle plumes
- monitoring concentrations at possible exposure points (domestic or irrigation
wells), and
- compliance with existing licenses and permits.
A program that relates every sample to one or more of these objectives would be
appropriate. The program should specifically identify the appropriate ("optimal")
network, sampling frequency, and analytical suite.
Note that the Access database of sampling results and other observations from the
Homestake is a very powerful data management tool, especially given the massive
amount of data that have been generated over the past 3 5 years or more. However, there
were noticeable errors in the database, such as in the measurement point elevations for
certain C series wells as noted above. An effort to identify and fix such errors should be
conducted, and it may be necessary to review the quality control processes for data entry
to the site database.
41
Final 12/23/10
-------
Ground water piezometric measurements are necessary to:
- identify ground water flow direction changes that may affect plume migration
- support determination of capture zones for the extraction and injection systems
- support analysis of the lateral extent of saturated alluvium
Ground water piezometric monitoring should be addressed as part of the monitoring
program planning and in the future each event should represent a relatively complete
snapshot of the aquifer conditions over one relatively short period of time. The water
levels in wells near the limits of the saturated alluvium should be compared to estimated
top of rock elevations to assess changes in the extent of saturated alluvium and the
amount of ground water requiring capture.
7.1.2 Monitoring Network. The Homestake site monitoring program includes a
very large number of available wells for sampling and water level measurement,
comparable to any of the largest remediation sites in the US. There are more than an
adequate number of wells available for monitoring the conditions in the alluvial aquifer.
There are a number of areas at the site that could be adequately characterized with fewer
sampled wells due to the proximity of the currently sampled wells, including the area
near the former mill, downgradient of the southwest corner of the large tailings pile, and
near the evaporation ponds. The monitoring within the large tailings pile needs to be
standardized with specific wells suitably screened within the tailings used for monitoring.
The use of the dewatering/injection wells with very long screens makes the interpretation
of the results very difficult. It is likely that the number of wells sampled in the large
tailings pile could be decreased, provided the remaining wells are adequately distributed
and represent the ambient conditions.
The monitoring networks for the Chinle aquifers are sparser than for the alluvial
aquifer. In evaluating the available data for the Upper and Middle Chinle aquifers, it is
apparent that there are areas where the plumes are not well bounded, particularly in the
northern portion of section 35, north of Broadview Acres. Additional sampling would
appear to be necessary there. In addition, additional wells would be useful to bound
plumes in the Upper Chinle aquifer southeast of the large tailings pile, and in the Middle
Chinle around CW-1.
7.1.3 Monitoring Frequency. Based on a review of ground water samples taken
in 2008 and 2009 (through July), approximately 365 wells were sampled at some point in
that period. Most wells did not appear to be sampled on a regular basis, but the sampling
occurred with an approximate frequency of either annual (about 190 wells) or semi-
annual (about 85 wells). Only about 15 wells had a sampling frequency that appeared to
approximate a quarterly sampling schedule. At least 70 wells were sampled less than
once per year. This represents a major investment in time and cost for the collection and
analysis of the samples, and the validation and management of analytical results.
The frequency of sampling should be based on the use of the data and should consider
the impact of unexpected results on decisions at the site, the time necessary to take action
if additional actions are needed, the rate at which ground water may migrate, the timing
42
Final 12/23/10
-------
of changes to the remedy that may affect the plume (e.g., significant changes in the
pumping or injection locations and rates), and the frequency with which the collected
data are assessed by the project team. Given the nature of the alluvial aquifer ground
water velocities (estimated to be on the order of magnitude of 500 ft/year), the nature of
the potential human exposures at the site, the degree to which Homestake staff can
rapidly respond to changes in the plume, and oversight given to the conditions at the site,
the sampling frequency does not need to be extreme. Qualitatively, the sampling
frequency could be annual, with semi-annual sampling at key locations upgradient, side-
gradient, and downgradient of extraction systems. Compliance point wells should
continue to be sampled according to all existing requirements.
7.1.4 Sampling Methodology and Analytical Suite. The current use of low-flow
sampling appears to provide good quality data. The use of no-purge sampling
techniques, such as Hydrasleeves and Snap samplers may be considered to reduce the
time necessary to sample the wells. A demonstration of these techniques side-by-side
with current practices could demonstrate comparability between results obtained using
each method. Refer to the Interstate Technology and Regulatory Council Technical
Regulatory Document on "Protocol for Use of Five Passive Samplers to Sample for a
Variety of Contaminants in Groundwater" (ITRC, 2007). Note that any comparison
should identify the presence of mineral precipitates, particularly iron oxides, in the
monitoring wells that may act to accumulate radionuclides and to increase turbidity in
samples. If any dedicated tubing or pumps appear to have such accumulations, the no-
purge sampling methods may not be appropriate.
The analytical suite can be evaluated based on the known distribution of the site
contaminants. Given the long history of sampling in most site wells, the expected
contaminants in different portions of the site could guide what analyses are chosen for
samples from those areas. Though it is not recommended to tailor the suite of analytes
for each individual well, wells to be sampled could be grouped by their general location
relative to the sources and the mobility of the various contaminants. Again, the
objectives for the sampling need to be considered.
7.1.5 Further Optimization Opportunities. Given the size and complexity of the
monitoring program at the site, further quantitative optimization studies for the program
are likely to be warranted. Homestake is encouraged to apply tools such as MAROS,
GTS, or the Summit monitoring optimization tools. Refer to the EPA/USACE Roadmap
to Long-Term Monitoring Optimization (EPA 542-R-05-003, 2005, available at
http://www.frtr.gov/optimization/monitoring/ltm.htm).
7.2 Air Monitoring Program
7.2.1 Environmental Monitoring Objectives. The broad objective for the air
monitoring program completed annually at the Homestake site is to ensure compliance
with the regulatory requirements of 10 CFR 40 and 10 CFR 20 with respect to the
exposure of members of the public from licensed activities at the site. As stated in the
Semi-Annual Environmental Monitoring Report for July-December 2008 that was
transmitted to NRC in February 2009, the design of the monitoring program is closely
43
Final 12/23/10
-------
based on the guidance contained in NRC's Regulatory Guide 4.14, Revision 1, which was
published in April 1980. The Semi-Annual Report acknowledges that some monitoring
activities differ from those presented in the Regulatory Guide but does not provide
additional information to identify or support those differences. The air monitoring
program requirements to ensure compliance with occupational dose limits for HMC
workers are also discussed in the Semi-Annual Report, but the results of monitoring are
not provided. The August 2008 NRC Inspection Report 040-08903/08-001, determined
that routine occupational air monitoring was not required due to the lack of exposed dry
tailings. Radon flux measurements are also performed annually and are reported in the
Annual Monitoring Report.
7.2.2 Monitoring Network. The number and location of monitoring stations for
particulate and radon gas sampling meet the minimum requirements outlined in Table 2
of Regulatory Guide 4.14. Those requirements are for continuous monitoring at three
locations at or near the site boundary that have the highest predicted concentration of
airborne particulates; one or more locations at the nearest residence or occupiable
structure; one control location; and five or more radon gas monitors collocated with the
particulate samplers. See monitoring locations map in Figure 21 below.
The Semi-Annual Report indicates that the predominant wind direction is from the
Southwest and locations HMC-1, -2, and -3 are identified as the locations with the
highest predicted air particulate concentration. No meteorological data for the
monitoring period is provided to confirm that conclusion. Wind direction data from the
on-site meteorological station should be collected during each monitoring period and
presented in the report. HMC included a wind rose in the 2009 Annual Irrigation
Evaluation Report submitted to NRC. A similar figure should be provided with the air
monitoring results in the Semi-Annual Environmental Monitoring Reports.
Monitoring locations HMC-4 and -5 are considered by HMC to be representative of
the nearest residence. This assumption appears appropriate for assessing the dose from
windborne particulates from the HMC site. The number of monitoring locations for
radon gas in the residential area may not be sufficient. Results of sampling conducted
during June-December 2008 show that the highest radon concentrations are not
associated with the locations in the dominant wind direction. In fact, the highest
measured radon concentration for this period was associated with HMC-6, the location
that is considered the control for air particulate sampling. This may indicate that the
preferred radon pathway from the site is not dependent on wind direction but on some
other process. It is likely that additional radon monitors, 2 to 3, located between the
current monitoring stations near the residential areas would be cost-effective at assessing
the apparent preferential radon pathway direction.
The number and location of control monitoring stations may not be adequate to meet
the overall objective of ensuring compliance with the public dose limit in 10 CFR
20.1301. As calculated in Attachment 4 to the Semi-Annual Report, the Total Effective
Dose Equivalent estimated for the maximum exposed individual is highly dependent on
three assumptions: that the radon background from location HMC-16 is representative of
background in the HMC-4 and -5 areas; that use of an occupancy factor other than 1 for
44
Final 12/23/10
-------
the exposed member of the public is appropriate; and the equilibrium concentration ratio
between radon gas and its decay products. The equilibrium issue is discussed in Section
.2.4 below.
The HMC report should better describe why different background locations are
appropriate for air particulates and radon gas monitoring based on observed pathway
differences. Additionally, the use of multiple radon background locations should be
considered as it may better represent the distribution of background radon concentrations
in the area potentially impacted by Homestake effluent releases. Historical studies of
other uranium tailings piles (Shearer, 1969) have observed that atmospheric radon
concentrations were not impacted beyond a distance of 0.5 mile from the pile.
The use of occupancy factors is generally not allowed when comparing site boundary
concentrations directly to those in Table 2 of Appendix B of 10 CFR 20. If 10 CFR
20.1302(b)(2)(l) is used to determine compliance with the public dose limit, an
occupancy factor of 1 is generally required. See NRC position at,
http://www.nrc.gov/about-nrc/radiation/protects-you/hppos/qa68.html. The use of an
occupancy factor is allowed when calculating the dose for the maximum exposed
individual, however, the 75% (271 days/yr) used in the calculation is for an average
resident and may not be appropriate, unless confirmed annually, for some residents that
are not away from home 6 hours per day.
Homestake is also required to monitor the radon flux from the LTP and STP on an
annual basis. HMC uses two simplifying assumptions for determining compliance with
the radon flux limit of 20 pCi/m2s that should be confirmed. The assumption that the
radon flux from the LTP side slopes has remained constant since 1994/1995 when last
measured should be reconsidered given the amount of potential movement of
contaminants within the pile caused by the flushing program. It is assumed that it will be
also measured again as part of the final closure. The assumption that the flux from the
large STP area covered by the evaporation ponds is 0 pCi/m2s needs to be justified.
Recent monitoring of the radon flux from EP-1 by HMC indicates that the flux is greater
than 0 pCi/m2s and the report calculations should be modified to include this new data.
Though radon has the potential to diffuse into the ponds from the STP below, it is more
likely that radium-226 in pond sludge may be providing a source of radon that could be
easily released through the spraying program. The HMC assumption that the Rn-222
concentration in the evaporation pond water is equal to the Ra-226 concentration in the
water is inconsistent with general groundwater conditions where the Rn-222
concentration is generally many times higher than the dissolved Ra-226 value. This
assumption should be checked by sampling the pond water for Rn-222 and the estimation
of Rn-222 released by spraying modified.
7.
7.2.3 Monitoring Frequency. The air monitoring frequency currently
implemented at the Homestake site is appropriate for meeting the overall objectives of
the program.
45
Final 12/23/10
-------
7.2.4 Sampling Methodology and Analytical Suite. The radionuclides monitored
at HMC, uranium, thorium-230, and radium-226 are all those identified in Regulatory
Guide 4.14 except for lead-210. This discrepancy should be discussed in the reports and
the basis for not including the radionuclide identified.
The air particulate data reported from the contract laboratory should be required to
indicate actual results instead of less than the lower limit of detection. The error
estimated by the laboratory for the uranium results should not be given as "not
applicable." Though mass spectroscopy method may have less inherent error than
radiochemical methods, the total estimated error including air sampling, etc. should be
determined. Changes were made in the 2009 Semi-Annual Environmental Monitoring
Report to improve laboratory data reporting.
As identified in 7.2.2 above, the radon decay product /radon equilibrium fraction is
extremely important in determining the dose from exposure to radon gas. Homestake
assumes a 20% radon decay product equilibrium in their calculation of the committed
effective dose equivalent to the maximum exposed individual. HMC should perform
appropriate sampling to confirm the validity of the assumed equilibrium under various
diurnal and seasonal fluctuations.
7.2.5 Further Optimization Opportunities for the Site Monitoring. As
discussed in Section 8.1.3 below, EPA is currently panning for additional air and radon
sampling within the residential areas of the site to support a human health risk
assessment.
46
Final 12/23/10
-------
Figure 21
Homestake Mining Company Properties
Grants, NM
Air Monitoring & Sampling Locations
Location Id
HMC1
HMC2
HMC3
HMC4
HMC5
HMC6
HMC7
HMC 16
(BKG)
Sampling Unit
Hi-Volume Partculate Monitor, Track -Etch Passive Radon Gas Monitor &
OSL Gamma Badge
Hi-Volume ParSculate Monitor. Track -Etch Passive Radon Gas Monitor &
OSL Gamma Badge
Hi-Volume Partculate Monitor, Track -Etch Passive Radon Gas Monitor &
OSL Gamma Badge
Hi-Volume Partculate Monitor, Track -Etch Passive Radon Gas Monitor &
OSL Gamma Badge
Hi-Volume Paniculate Monitor, Track -Etch Passive Radon Gas Monitor &
OSL Gamma Badge
Hi-Volume Partculate Monitor, Track -Etch Passive Radon Gas Monitor &
OSL Gamma Badge
Track-Etch Passive Radon Gas M onitor
Track-Etch Passive Radon Gas Monitor & OSL Gamma Badge
Northing
1547458.838
1546349.53
1543048.74
1538751.127
1541268.442
1543813.054
1540395.708
1556470.456
Easting
491370.45
495053.16
495640.47
488918.03
488546.31
486297.26
493293.8
485135.12
® Air Monitors
Roads w
+ Gates
| I Fence Lines
1 Section Lines
FIGURE 1
0 0.25 0.5
==••£==•
Final 12/23/10
I Miles
Page 47
-------
8 IRRIGATION WITH CONTAMINATED WATER
8.1 Risk Issues. Since 2000, Homestake has applied uranium and selenium
contaminated irrigation water to four fields corresponding to approximately 400 acres.
Contaminant concentrations in the irrigation water and affected soils are sampled each
year and a report summarizing the 2000-2008 monitoring program was published in
March 2009. The 2009 Annual Irrigation Evaluation report, published by HMC in
March 2010, includes measurements of selenium and uranium concentrations in hay
grown on the irrigated land, a RESRAD dose assessment, and air dispersion modeling for
radon released from irrigated lands.
8.1.1 Uranium Radiological Dose/Risk Estimation. The RESRAD computer
code, Version 6.5, developed by Argonne National Laboratory was used to estimate the
radiological dose and risk that may be incurred by a future resident living on the irrigated
land. The RESRAD code uses a sorption-desorption ion-exchange model to estimate the
leaching of soil contamination to groundwater. The leaching of uranium from the
irrigated lands back into the alluvial aquifer was identified as concern by the RSE
Advisory Group. The default contaminated zone area, 10,000 square meters, was used in
the RESRAD calculation with a homogenous layer of contamination 2 meters thick with
100 meters parallel to the aquifer flow. The concentrations of the three uranium isotopes
were input as 10 picocuries per gram (pCi/g) of uranium-23 8, 10 pCi/g of U-234, and 0.5
pCi/g of U-235. This activity corresponds to 30 mg/kg of natural uranium, and should be
sufficient to address potential buildup from additional irrigation, if performed. Uranium
decay products were initially set at 0 pCi/g and allowed to in grow over a 1000 year
calculation period. Several site specific water and soil parameters were used and are
highlighted in the RESRAD Summary Report in Appendix F All pathways in the model
were included and the receptor was modeled to be present on-site 100 percent of the time,
divided equally between indoor and outdoor activities. The results of modeling indicate
that because of site specific conditions and the depth to groundwater in these areas, it is
not expected that uranium in the upper two meters of soil will have a significant impact
on groundwater in the alluvial aquifer. Because the dose, and risk, is mainly driven by
external radiation exposure and ingestion of plants grown in the contaminated soil, the
dose decreases rapidly after several hundred years as the uranium in the contaminated
zone is removed by various processes, including erosion (erosion assumed to be 1 mm/yr,
largely due to wind action).
The RESRAD model does not address the dose and risk from the use of contaminated
irrigation water that is not associated with leaching from the contaminated zone. To
assess the potential dose from the continued use of contaminated irrigation water, an
additional RESRAD run was made using the same contaminated zone and irrigation rate
yet leaving other soil and water parameters at the default settings. Using these inputs,
contamination leached to groundwater and the uranium contaminated well water was then
used for irrigation. The input soil concentrations were adjusted so that the leached
uranium concentrations in well water were equivalent to the 0.44 mg/L total uranium
irrigation limit that has been used since 2000. The resulting well water uranium isotope
concentrations of 147 pCi/L U-238, 147 pCi/L U-234, and 6.1 pCi/L U-235 equate to 300
pCi/L total uranium which is equivalent to 0.44 mg/L assuming natural abundance. At
48
Final 12/23/10
-------
the point in the model when the well water uranium concentrations had reached 300
pCi/L, the uranium levels in the contaminated zone had been significantly reduced by
erosion. The resulting water dependent pathway doses are attributable only to the use of
contaminated irrigation water. It is assumed that the resident will continue to use
contaminated irrigation water while living on the contaminated zone, therefore the doses
and excess cancer risks from all pathways are summed and presented in the Tables 7 and
8 below.
The largest contributor to the estimated dose and risk is the consumption of plants
irrigated with contaminated water. Overall excess cancer risk is near the top of the
CERCLA risk range 1E-06 to 1E-4. There are many conservative assumptions included
in this estimate and none of the irrigated areas are currently inhabited. Two potential
exposure pathways that were not included in this estimation were the direct ingestion of
contaminated groundwater and use of water with uranium concentrations greater than
0.44 mg/L for irrigation.
Table 7
RESRAD
Pathway
Ground (External)
Inhalation
Radon
Plant
Meat
Milk
Soil
All Pathways
Summary of Estimated Dose for Resident on Irrigated Land
(mrem/yr)
Water
Independent Dependent* Total
1 .52 — 1 .52
0.25 — 0.25
0.29 0.04 0.33
1.23 10.5 11.7
0.04 0.49 0.53
0.10 1.07 1.17
0.21 — 0.21
3.64 12.1 15.7
*Water dependent pathway doses are associated with the continued use of contaminated
irrigation water at the historically limited concentration of 0.44 mg/L total uranium. All maximum
water independent doses occur at year=0 except radon maximum water independent dose at
year=1000 is used.
Table 8
RESRAD
Pathway
Ground (External)
Inhalation
Radon
Plant
Meat
Milk
Soil
All Pathways
Summary of Estimated Excess Cancer
Irrigated Land
Water
Independent
3.3E-05
1 .5E-06
5.1E-06
1 .4E-05
4.6E-07
1.1E-06
2.3E-06
5.7E-05
Dependent*
7.8E-07
1.1E-04
4.4E-06
1 .2E-05
1 .3E-04
Risk for Resident on
Total
3.3E-05
1.5E-06
5.9E-06
1 .2E-04
4.9E-06
1.3E-05
2.3E-06
1.8E-04
*Water dependent pathway risks are associated with the continued use of contaminated irrigation
water at the historically limited concentration of 0.44 mg/L total uranium. All maximum water
independent risks occur at year=0 except radon maximum water independent risk at year=1000 is
used.
49
Final 12/23/10
-------
8.1.2 Selenium Soil Screening Level Comparison. In the March 2009 Irrigation
Report, Homestake compared the selenium concentrations measured in hay to the
National Research Council maximum tolerable concentration (MTC) for selenium in
cattle feed of 2 mg/kg. This is an important consideration as the average selenium
concentrations have historically been slightly below the MTC. In 2009, different grasses
were planted and may concentrate selenium better than the previous hay varieties. The
actual concentration should be confirmed prior to using the grasses for cattle feed.
The EPA Regional Screening Levels for Chemical Contaminants at Superfund Sites
web-based calculator, http://epa-prgs.ornl.gov/cgi-bin/chemicals/csl search, provides a
resident noncarcinogenic risk-based screening level for selenium in soil of 391 mg/kg.
This is well above levels in the irrigated areas. Even considering the multiple
contaminants present, the uptake of selenium in plants potentially used for cattle feed is
more of a concern at the levels currently present.
8.1.3 EPA Risk Assessment. EPA is currently planning to implement additional
sampling throughout the residential and irrigated areas to support a complete human
health risk assessment. EPA has discussed the scope of work for the risk assessment with
the RSE advisory group.
8.2 Future Alternatives
8.2.1 Treatment of Irrigation Water. An alternative to the current practice of
directly applying untreated extracted groundwater for irrigation is removal of
contaminants above the discharge levels through treatment before application to the land.
Currently, the maximum allowable concentration of uranium (0.44 mg/L) in irrigation
water is based on NRC effluent release criteria and the maximum allowable selenium
concentration is based on a site-specific background value. Though not specifically
applicable to irrigation water, the New Mexico Water Quality Control standards for
uranium (0.03 mg/L) and selenium (0.05 mg/L) are much lower than the irrigation
discharge maximum concentrations. This alternative is developed in response to
stakeholder concerns and to provide the regulatory agencies with a potential course of
action for treatment, regardless of the driving reason.
A treatment system similar to that currently used in the treatment plant (chemical
pretreatment, followed by removal of salts and metals by reverse osmosis) was
considered impracticable because of the long distances needed to transport the reject
water from the chemical pretreatment to the evaporation ponds (4-5 miles by road) and
the undesirability of transporting waste through the residential communities in which the
areas of irrigation are located.
An alternative treatment alternative was developed using ion exchange. The relatively
high calcium and bicarbonate concentrations in the irrigation water suggests the uranium
is either in a non-ionic form or is present in an anionic form. If present in a non-ionic
form, pretreatment of calcium by ion exchange with a cationic resin may be necessary
and would result in the uranium forming anions that would be treated by available
50
Final 12/23/10
-------
uranium removal resins. The pretreatment would result in the need to regenerate the
softening resins. The brine from the regeneration would need to be transported to the
evaporation ponds. Based on brine production in municipal softening system, this is not
expected to be excessive, but would represent additional effort and truck traffic back to
the main treatment plant.
The irrigation water chemistry (Table 9) was provided to REMCO Engineering (805-
658-0600, http://www.remco.com/ixidx.htm), who indicated that the company has
resin(s) highly selective for uranium. The capital costs for a uranium treatment system
(two columns in series with a particulate filter, assuming use of existing extraction well
pumps to pump the water to the treatment plant) are estimated to be -$750,000, with
O&M costs of approximately $100,000 per year (assuming 400 cu ft of resin would be
used at a cost of $200/cu ft). Spent uranium-specific resin could be either disposed of on-
site or off-site. On-site regeneration of the resin through the use of a sodium chloride
brine may be an alternative (see for example, http://www.adedgetech.com/uranium.html).
In this case, the brine would be collected and trucked to the evaporation ponds for
disposal.
Table 9. Average Concentrations of Species in
Homestake Untreated Irrigation Water
Species
Cations
Sodium
Potassium
Magnesium
Calcium
Dissolved Iron
Metals
Uranium
Selenium
Average
Cone
(mg/L)
285
8
65
242
0
0.28
0.06
Species
Anions
Bicarbonate
Carbonate
Sulfate
Chloride
Nitrate
Average
460
0
840
180
3.5
8.2.2 Reduction of the Mobility of Uranium in Soil. Although leaching of
uranium is not considered to be a likely risk, mobility of the uranium in the irrigation soil
could potentially be reduced through application of soil amendments such as organic-rich
materials (e.g., compost or manure) or a phosphate-rich material such as bone meal.
Since the impacts to ground water were not anticipated to be significant, these options
were not researched further, but may be considered if other information comes to light
that suggests that uranium immobilization may be necessary.
51
Final 12/23/10
-------
9 SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS
9.1 Conclusions. The current remediation systems have been successful at
reducing concentrations in ground water at the site and Homestake/Barrick seems to have
truly been conducting the work with the intent of restoring the environment. There are a
number of major conclusions from the evaluation of the efforts.
• Ground water remediation is very unlikely to be achieved by 2017.
• Flushing of the large tailings pile is unlikely to be fully successful at
removing most of the original pore fluids or to remediate the source mass
present in the pile due to heterogeneity of the materials.
- There is a potential for rebounding in contaminant concentrations in the
pile following cessation of flushing.
- The addition of water to the tailings complicates the capture of
contaminated water from the alluvial aquifer
• Long screened intervals in wells complicate the interpretation of water
quality in and below the large tailings pile.
• An additional source may be located in the vicinity of the former mill site
• Control of the contaminant ground water plumes seems to depend on both
hydraulic capture and dilution
• Proposed pilot testing of immobilization approaches in and below the LTP
may be valuable.
• There may have been widespread impacts on the general water quality (e.g.,
ions such as sulfate) of the alluvial aquifer since mill operations began, but
the limited amount of historical data precludes certainty in this conclusion.
• Upgradient water quality has declined over time, primarily in the western
portion of the San Mateo drainage and this may be affecting concentrations
in northwestern portions of the study area.
• Ground water modeling has generally been done in accordance with
standard practice. The seepage modeling likely overestimates the efficiency
of flushing of the tailings.
• The control of a uranium plume in the Middle Chinle aquifer may be
incomplete
• There are no apparent impacts to the San Andres aquifer, though the number
of wells in the San Andres in the study area is relatively small.
52
Final 12/23/10
-------
• There is no indirect evidence of leakage from the evaporation and collection
ponds, though the interpretation of water level and concentration data are
complicated by the significant injection and extraction conducted in the
immediate vicinity of the ponds.
• Current constraints to treatment plant operations include the evaporative
capacity of the ponds, clarifier operation, and possibly RO capacity.
• Evaporation rates for the ponds at the site are likely to be in the 65-80 gpm
on an annual basis when accounting for climatic conditions and salinity of
the pond contents
• The monitoring program at the site is extensive and not clearly tied to
objectives.
- The potential monitoring network is very large, particularly in the alluvial
aquifer. There may be redundancies in the network in a number of locations
in the alluvial aquifer. Additional monitoring points are necessary in the
Upper and Middle Chinle aquifers to better define plume extent and
migration.
- Monitoring frequency is irregular but generally from semi-annual to
annual. Only a relatively small number of wells are sample more or less
frequently in recent years.
- Air particulate monitoring appears adequate to assess anticipated effluent
releases from the site; however, there is a need to confirm assumptions
regarding radon background, preferential radon flow direction and radon
decay product equilibrium that may require additional sampling.
- Potential for release of radon from the STP/evaporation pond area should
be assessed.
• Irrigation with contaminated water has resulted in accumulation of site
contaminants in the soil of the irrigated land. These accumulations are
unlikely to migrate to the water table over time, however.
• Water used for irrigation could be successfully treated with ion exchange
technology
9.2 Recommendations. Based on the analyses conducted, a number of
recommendations are offered below. Note that regarding several issues, no specific
recommendations are made, but the conclusions from the analysis could be used by
all agencies and stakeholders in assessing future actions.
• The flushing of the tailings pile should be ended. If this is not adopted, a
pilot test of the potential for rebound in concentrations should be conducted
in a portion of the tailings pile. Monitoring should be conducted in depth-
specific wells with short screen lengths.
53
Final 12/23/10
-------
• If the field pilots to reduce uranium concentrations in the groundwater
through adsorption or in-situ precipitation are approved and the results from
the pilots are promising, apply in larger scale to applicable portions of the
LTP and the groundwater.
• Simplification of the extraction and injection system is necessary to better
focus on capture of the flux from under the piles and to significantly reduce
dilution as a component of the remedy.
• Further evaluate capture of contaminants west of the northwestern corner of
the large tailings pile.
• If not previously assessed, consider investigating the potential for
contaminant mass loading on the ground water in the vicinity of the former
mill site.
• Further investigate the extent of contaminants, particularly uranium, in the
Upper and Middle Chinle aquifers and resolve questions regarding
dramatically different water levels in wells in the Middle Chinle.
• Additional collection of geochemical parameters, including dissolved
oxygen and oxidation reduction potential, of the groundwater beneath and
downgradient of the LTP to characterize the geochemical environment and
the role that reducing conditions induced by the flushing have had in
immobilization of the selenium (and the potential that cessation of the
flushing may lead to less reducing conditions and release of the selenium).
• Consider geophysical techniques, such as electrical resistivity tomography
to assess leakage under the evaporation ponds
• Assure decommissioning of any potentially compromised wells screened in
the San Andres Formation is completed as soon as possible.
• Consider construction of a slurry wall around the site to control contaminant
migration from the tailings piles. The decision for implementing such an
alternative would depend on the economics of the situation. Though HMC
has conducted previous economic analyses of this alternative, the analysis of
the payback due to reduced (but not eliminated) cost of operations of the
ground water treatment system was not attempted for this study, could be
revisited in light of other recommendations.
• Relocation of the tailings by any means should not be considered further
given the risks to the community and workers and the greenhouse gas
emissions that would be generated during such work.
54
Final 12/23/10
-------
• Consider either the pretreatment of high concentration wastes in the
collection ponds as is currently being pilot tested, or adding RO capacity to
increase treatment plant throughput and reduce discharge to the ponds
• Review of the spray evaporation equipment and potential optimizations of
the equipment to increase the rate and efficiency of evaporation.
• Develop a comprehensive, regular, and objectives-based monitoring
program.
- The evaluation should identify redundant alluvial aquifer wells for
exclusion from the program (e.g., near the former mill site and southwest of
the large tailings pile).
- Identify additional well locations required in the Chinle aquifers to better
define the plumes.
- Sampling frequency should be annual with semi-annual sampling in
critical areas.
- Quantitative long-term monitoring optimization techniques are highly
recommended.
- Any optimization effort should include an open discussion with
stakeholders.
- Consider passive samplers.
- Perform sampling of radon decay products to confirm equilibrium
assumption.
- Consider use of multiple radon background locations to better represent the
distribution of potential concentrations.
- Reconsider the use of the 0.75 occupancy factor and use a value of 1 in
accordance with NRC guidance.
- Assess the concentration of radon in evaporation pond water and the radon
gas potentially released from the evaporation ponds, especially during active
spraying.
• Though risks appear minimal with the current irrigation practice, consider
treatment of contaminated irrigation water via ion exchange prior to use as a
means of removal of contaminant mass from the environment.
9.3 Approach to Implementation of Recommendations. Some of the
recommendations can and should be implemented without consideration of other
recommendations. Some recommendations can only be implemented in conjunction with
others or depend on the outcome of additional characterization or studies. A suggested
approach to implementation of the recommendations is provided here.
The recommendations that should proceed independent of any other
recommendations include: 1) the evaluation of the potential escape of contaminants at
the northwestern portion of the site, 2) the evaluation of the vicinity of the former mill
site as a potential source of ground water contamination, 3) further characterization of the
extent and migration of the Chinle plumes, 4) complete decommissioning of potentially
compromised San Andres wells, 5) development of a comprehensive, optimized
55
Final 12/23/10
-------
monitoring program, and 6) implement treatment of contaminated irrigation water to
remove contaminant mass from the environment.
Several recommendations should be part of a fresh look at the overall ground water
remediation strategy for the area around the tailings piles. Tailings flushing should be
discontinued in conjunction with revamping of injection locations in the alluvial aquifer
to minimize recirculation of water. At the same time, pumping should be allocated in
areas to assure full capture of the flux of water from and under the tailings. Based on this
evaluation, the need for modification to the treatment plant and the true need for
evaporative capacity should be further considered.
56
Final 12/23/10
-------
10 REFERENCES
Environmental Quality Management, (2008) Draft Final Remediation System Evaluation,
Homestake Superfund Site, Grants, NM, December 19, 2008
Federal Remediation Technology Roundtable (FRTR, 2002) "Evaluation of Permeable
Reactive Barrier Performance", prepared by the Tri-Agency Permeable Reactive Barrier
Initiative, December 2002.
Fryxell, G.E., etal., (2005), Environ. Sci. Technol., 39, 1324-1331.
Hochstein, Ron F., Rod Warner, and Terry Wetz, 2003. Transportation of the Moab
Uranium Mill Tailings to White Mesa Mill by Slurry Pipeline, Proceedings, WM '03
Conference, Tucson, 23-27 February 2003.
Homestake Mining Company, (HMC, 2009a), 2008 Annual Monitoring
Report/Performance Review for Homestake's Grants Project, March 2009.
Homestake Mining Company, (HMC, 2009b), HMC Presentation (and related discussion)
to RSE Addendum Stakeholders and USACE team, April 2009.
Homestake Mining Company (HMC, 2009c), Treatment Plant Data (Sept 2009) supplied
directly from Homestake Mining Company records to the USACE, response to 19
September 2009 Homestake/USACE teleconference.
Homestake Mining Company (HMC, 2010a), Homestake and USACE teleconference, 22
January 2010.
Homestake Mining Company, (HMC, 201 Ob), "Treatment Alternatives Testing in the
Large Tailing Pile", Letter from Homestake Mining Company (Alan D. Cox) to John T.
Buckley, U.S. Nuclear Regulatory Commission, 13 August 2010 .
Hydro-Engineering LLC, (2006), Ground Water Modeling for Homestake's Grants
Project, April, 2006, Appendix C to Groundwater Corrective Action Program Revision,
December, 2006.
Interstate Technology and Regulatory Council (ITRC), (2007), Technical Regulatory
Document on "Protocol for Use of Five Passive Samplers to Sample for a Variety of
Contaminants in Groundwater"
ITRC (in press), Technical Regulatory Document on "Remediation Risk Management"
Remediation Technologies Development Forum (RTDF), (2001), RTDF Permeable
Reactive Barrier Action Item, May 24, 2001,
http://www.rtdf org/PUBLIC/PERMB ARR/prbsumms/profile. cfm?mid=47.
57
Final 12/23/10
-------
SERDP (2000) "Design Guidance for Application of Permeable Reactive Barriers for
Groundwater Remediation", prepared by Battelle, Inc. 31 March 2000.
Shearer, Jr., S.D. and Sill, C.W., (1969), "Evaluation of Atmospheric Radon in the
Vicinity of Uranium Mill Tailings", Health Physics Vol. 17, pp. 77-88.
Skiff and Turner, (1981), Alkaline Carbonate Leaching at Homestake Mining Co., paper
provided by HMC, published in 1981
US Environmental Protection Agency (EPA) and US Geological Survey (2000) "Field
Demonstration of Permeable Reactive Barriers to Remove Dissolved Uranium from
Groundwater, Frye Canyon, Utah, September 1997 through September 1998 Interim
Report, EPA 402-C-00-001, November 2000
US EPA/USACE, (2005), Roadmap to Long-Term Monitoring Optimization (EPA 542-
R-05-003, 2005, available at http://www.frtr.gov/optimization/monitoring/ltm.htm)
US EPA (2008), EPA 402-R-08-005, Technical Report on Technologically Enhanced
Naturally Occurring Radioactive Materials from Uranium Mining, 2008
Wellman, D.M. (2007), et al., Environ. Chem. 2007, 4, 293-300.
58
Final 12/23/10
-------
APPENDIX A - RSE ADDENDUM SCOPE OF WORK
Final 12/23/10
-------
Scope of Work
Final 8/20/09
US Army Corps of Engineers Environmental and Munitions Center of Expertise
Focused Review of Specific Remediation Issues
Homestake Mining Company (Grants) Superfund Site, New Mexico
Based on discussions between the US Environmental Protection Agency (USEPA) and
the New Mexico Environmental Department (NMED), interested stakeholder groups, and
Homestake Mining/Barrick Gold, the following tasks will be performed by the US Army
Corps of Engineers (USAGE) Environmental and Munitions Center of Expertise (EM
CX) to supplement past Remediation System Evaluation work at the site. In general, the
review is intended to provide a critical review of the current remedial ground water
strategy, including whether other approaches or technologies could be incorporated that
may be more efficient and/or effective at achieving site closure goals. The outcome will
be a summary of any recommended modifications necessary to improve performance or
overcome performance deficiencies, or that would potentially reduce life-cycle costs or
time to achievement of remedial goals. The analysis will not address the issues regarding
the site background levels or specified cleanup goals. Specifically, the USAGE EM CX
would:
1) Evaluate the adequacy of plume capture, horizontally and vertically, of the ground
water plumes in the alluvial and Chinle aquifers, using the recent EPA guidance on
capture analysis (EPA, 2007) as a guide. The conceptual model of ground water flow
and contaminant transport in the natural aquifers would be evaluated and refined. No
ground water modeling will be conducted as part of the analysis, though a limited
assessment of the approach to ground water modeling conducted by Homestake will be
performed. As part of the evaluation, the effects of and alternatives to specific
components of the current remedial strategy including: a) pumping/injection in the Chinle
and alluvial aquifers, b) diversion of ground water upgradient of the large tailing pile
(LTP), c) use of clean/treated water injection, and d) irrigating with untreated water in
downgradient areas would be evaluated. Capture analysis would be conducted using
analytical groundwater equations, preparation and analysis of piezometric maps, graphs
of contaminant concentrations in specific monitoring and production wells, and
professional judgment. Heterogeneity (e.g., channels, faults, etc.) in the subsurface
pathways, a range of site and climatic conditions, and site geochemistry will be
considered. The potential impacts from site conditions on the San Andres aquifer will be
addressed to the extent possible with existing information. Potential human health issues
surrounding the current irrigation practices would be assessed and alternatives to current
practices would be conceptually developed. Alternatives to current practices that may be
considered include, for example, different pumping and injection locations, in-situ
immobilization, passive treatment, deep-well injection, or other technologies. The
analysis will identify: areas where certainty of capture is low, recommendations for
further investigations, suggested alternative extraction/injection operational strategies,
necessary pilot testing, and, where possible, conceptual designs/descriptions of
alternatives. The evaluation will also address to the extent possible the likelihood that the
ground water restoration efforts will achieve performance objectives by the end of 2017.
No detailed designs or rigorous cost estimates would be prepared. The report will
-------
include a brief description of the conceptual model developed as part of the analysis.
Detailed descriptions of the site conditions will not be provided, though references for
such information will be cited.
2) Evaluate the overall strategy (including cost-effectiveness and protectiveness) of
flushing contaminants from the LTP and discharging contaminants to evaporation ponds
for eventual long-term entombment and to assess alternative remedial strategies. The
analysis will include the critical evaluation of the current conceptual model for flushing,
geochemical changes, heterogeneity, and evaluation of mass balance for water injected
and recovered from the toe drains, LTP extraction wells, and downgradient extraction
wells. The use of similar flushing approaches and the observed performance for such
applications will be researched. Alternatives to the current strategy (e.g., slurry walls,
immobilization, etc.) that would achieve the intended goal of restricting future
contaminant mass flux to the underlying aquifers would be conceptually developed. The
rough costs for such alternatives would be compared to a rough estimate of the costs,
risks, and environmental impacts of fully removing the tailings from the site. The ability
to monitor for leakage from the ponds will also be assessed through a qualitative review
of the monitoring well network in the vicinity of the ponds and an assessment of
inspection and repair methods. The results of the analysis would include a brief critique
of the current LTP conceptual model, descriptions and rough costs for any promising
alternatives to the current site actions at the LTP, and the assessment of the leakage from
the ponds. These would be documented in the report. No detailed designs or rigorous
cost estimates would be prepared.
3) Assess potential modifications to the reverse osmosis (RO) units and related treatment
components to achieve full capacity operations of the treatment plant. The analysis
would include development of conceptual designs for modifications to the existing plant
or addition of new equipment or alternative treatment processes to improve plant
effectiveness, throughput, and cost efficiency. These proposed modifications would be
developed in conjunction with the overall strategy for capture of site plumes and
management of the tailings piles. The role that increased RO system treatment capacity
would potentially play in alternative remedial strategies will be assessed. The
recommended changes or additions would be conceptually described in the report and
accompanied by rough cost estimates. No detailed designs or rigorous cost estimates
would be prepared.
4) Evaluate the projected evaporation rates for the new and existing ponds. This would
include independent calculation of lake evaporation considering salinity of the water in
the ponds, an evaluation of the need for spray evaporation enhancements with the
addition of the proposed [permitted?] evaporation pond 3, and an evaluation of
alternatives to spray evaporation enhancements. The impact on the necessary
evaporation rates due to alternative strategies for treating extracted water (or changes in
the flow rates to the ponds as a result of the analysis of the capture adequacy) would be
considered in comparing evaporative capacity to what is needed. Calculations,
explanations, and recommendations, if any, will be provided in the report.
-------
5) Assess the monitoring network for sufficiency (both laterally, vertically) and possible
redundancies, as well as to determine appropriate sampling frequency. The analysis of
ground water monitoring would be conducted using a non-quantitative approach that
considers:
- the rate of contaminant transport, including behavior of the different chemical
species
- previously observed variability in contaminant concentrations,
- historical trends in concentrations,
- frequency of routine data analysis by interested stakeholders,
- location of monitoring wells to potential receptors,
- locations of monitoring wells relative to other monitoring wells, and
- the time available to modify the remedy based on evidence of any unexpected
plume migration.
The recommended frequency and locations could be based on any or all of these
considerations. The results of the analysis would be tabulated in tables, maps, and/or
text in the report. The conclusions may include identification of areas possibly
requiring additional monitoring points, general sampling frequency recommendations
for wells in different parts of the site/plume, specific recommendations for sampling
frequency in certain wells, and possibly redundant monitoring wells. The report may
also make recommendations for sampling and analytical methods, data management,
and reporting requirements. The report may recommend a more detailed quantitative
analysis using more sophisticated software.
The current air monitoring program will also be critically evaluated regarding sampling
location, methods, analyses, frequency, and interpretation of results. The report will
provide recommendations, as appropriate, regarding these aspects of the air monitoring
program.
6) Evaluate the appropriateness of the current practice of irrigating with untreated water,
particularly in light of the new NMED and EPA water quality standard for uranium (0.03
mg/L). The analysis may include considerations of alternative operational strategies,
necessary additional monitoring or modification to the monitoring approach, potential
impact of recharge on ground water flow, and/or modifications to the current approach to
addressing downgradient portions of the contaminant plumes (including treatment). The
conclusions and recommendations will be documented in the report.
7) Qualitatively assess the small tailings pile (STP) as a potential source of ground water
contamination and need, if any, for ultimate capping of the STP beyond the planned
radon barrier. This assessment would primarily involve determination of historical
ground water concentration trends for wells around the STP and the assessment of the
means to assess leakage, if any, from Pond 1, as discussed in item 2 above. The results of
the assessment would be documented in the report text supported by various figures, if
appropriate.
-------
APPENDIX B - COMMUNICATIONS PLAN
Final 12/23/10
-------
Remediation System Evaluation (RSE)
Advisory Group and Communication Plan for the
Homestake Mining Company Superfund Site
Goals of the RSE Advisory Group and Communication Plan: The goals of the RSE Advisory
group are to provide an opportunity for citizens, the responsible party (RP), and other interested
stakeholders to interact with EPA in the development of the scope for the follow-on RSE, to
provide pertinent site background information that will be useful in preparation of the RSE, to
review draft and final RSE reports, and to provide a direct communication channel to EPA and
the regulatory agencies involved in preparing the RSE. The goal of the communication plan is to
document the communication strategy between individuals preparing the RSE, the RSE Advisory
Group, and the regulatory agencies.
RSE Advisory Group Members: RSE Advisory Group members will consist of a subset of
concerned citizens, technical advisors that support citizen interests, the site owner and site owner
representatives, regulatory personnel, and individuals performing the follow-on RSE. The
following table provides a list of proposed RSE Advisory Group members:
RSE Advisory Group Members
Name
Candace Head-
Dylla
Milton Head
Art Gebeau
Laura
Watchempino
Richard Abitz
Paul Robinson
Chris Shuey
AlCox
George Hoffman
Rocky Chase
Kathy Yager
Affiliation
Citizen cuhl48@psu.edu
BVDA
BVDA
Water Quality Specialist,
Pueblo of Acoma
Technical Support
contractor to BVDA
Southwest Research
Information Center,
Advisor to Pueblo of
Acoma
Southwest Research
Information Center,
Advisor to Pueblo of
Acoma
Homestake Mining
Company of California
HydroEngineering
Homestake Mining
Company of California
U.S. EPA Office of
Email Address
miltonhead@gmail.com 505-28'
gebeau@7cities.net
haakuwater@yahoo.com 505-55
rabitz@cinci.rr.com 513-226-53
sricpaul@earthlink.net 505-262-
sric.chris@earthlink.net 505-26^
acox@barrick.com
hydro@alluretech.net
rchase@barrick.com 801-990-3'
yager.kathleen@epa.gov 617-91
Phone Number
(optional)
505-404-4349
-3496
505-287-3613
2-6604
x5547
19
1862
-1862
505-400-2794
47
8-8362
-------
Sai Appaji
Donn Walters
Robert Ford
Jerry Schoeppner
David Mayerson
John Buckley
David Becker
Carol Dona
Brian Hearty
Superfund Remediation
and Technology
Innovation
U.S. EPA Region 6
U.S. EPA Region 6 waiters
U.S. EPA National Risk
Management Research
Laboratory
New Mexico
Environment Department
New Mexico
Environment Department
Nuclear Regulatory
Commission
RSE Team
RSE Team
RSE Team
appaji.sairam@epa.gov 214-665
.donn@epa.gov
ford.rober@epa.gov 513-569-75
jerry. schoeppner@state.nm.us 5<
david.mayerson@state.nm.us 50
John.Buckley@nrc.gov 301-415
dave.j .becker@usace.army.mil
carol.l.dona@usace.army.mil
brian.p.hearty@usace.army.mil
-3126
214-665-6483
31
)5-827-0652
5-476-3777
-6607
402-697-2655
402-697-2582
402-697-2478
Communication Plan: The primary form of communication will be through conference calls, the
internet, and email. Due to time and cost considerations, in person meetings will be kept to a
minimum. All individuals listed on the RSE Advisory Group will be included in all email
correspondence and invited to participate in all conference calls.
Proposed Conference Calls
1. RSE Advisory Group and Communication Plan Discussion: Purpose - to discuss the
draft RSE Advisory Group and Communication Plan
2. Scope of Work Discussion 1. Purpose - to discuss revised draft SOW for the USAGE
and finalize the RSE Advisory Group and Communication Plan
3. Scope of Work Discussion 2. Purpose - to discuss the final USAGE SOW
4. Progress Report. Purpose - for EPA and USAGE to report out on progress and
preliminary findings of the follow-on RSE and solicit input from the RSE Advisory
Group
5. Draft Report. Purpose - to discuss the draft Follow-on RSE report and RSE Advisory
Group Comments
6. Final Report - Purpose - to discuss RSE Advisory Group report comments, response to
comments, and changes to the draft Follow-on RSE report
7. Others as necessary
Timing of Conference Calls: It is proposed that conference calls be held at 12:00 noon Mountain
Time to accommodate individual work schedules, however the call schedule may change based
on future needs
-------
Posting of Information: All information related to the Follow-on RSE, the RSE Advisory Group,
and the Communication Plan will be posted on an internet site hosted by EPA referred to as the
Homestake Mining Company Lotus Notes Quick Place Site. User access will be provided to all
RSE Advisory Group members and other key contacts listed above. Each member will be
responsible for signing up to set up an individual username and password.
https://epaqpx.rtp.epa.gov/QuickPlace/homestake/Main.nsf?OpenDatabase
Types of information to be posted on the Quick Place Site:
1. All documents reviewed as part of the Follow-on RSE
2. The RSE Advisory Group Communication Plan
3. Draft and final reports
Individual Communications: All individual communications between a RSE Team and a
member of the RSE Advisory Group shall be summarized in written format by the RSE Team
Member and posted on the Quick Place Site under a subsection called "Individual
Communication". The purpose of this documentation is to ensure that all information
communicated to the RSE Team is also communicated to all members of the RSE Advisory
Group.
-------
APPENDIX C - OUTPUT FROM SUSTAINABLE REMEDIATION TOOL
Final 12/23/10
-------
SRT Input Current Pump&Treat System
1
1
Design for Managing Groundwater
Airline miles flown by project team (total miles for all traveler;
Average Distance Traveled by Site Workers per one-way tri|
Trips by Site Workers during construction
Trips by Site Workers after constructor
Remediation Design (Purpose)
Duration (must be <1 00 years)
Total pumping rate
Tier 2 Change
Calculated Values Number of wells
(dark9raybOX9S| Length ofmanifold
Treatment Method
Beginning Plume Mass
Ending Plume Mass
Original Plume
Plume Area
Plume Length
Plume Volume
i
5
0
44000
miles over proj lifetime
miles one-way
# over project lifetime ,
# over project lifetime
Containment ,| _|
50
I I
Activated Carbon ••
acres
feet
million gallons
kg
years I
gpm
I
] J
kg
kg
After Project
feef
mil gals Ad
C02E
= Use this default value or override with - .-.^n
Restore Defaults
jy Pump & Treat
]^j— -I U |nput I », T Enhanced Bioremedialion _ »| Resu\ts I
n In Situ Chemical Oxidation ' '
I7PRB
|~ LTM/MMA ••
Materials and Consumable Amounts Used for Metrics
PVC As
Steel Ibs
Activated carbon Ibs
Electricity kWh
Diesel (CapitalJ gal
Diesel (O&M) gal
Gasoline (Capital) gal
Gasoline (O&M) gal
Natural gas| \rncf
Technology Cost
Project-specific Metrics (Add & Subtract/Offsets)? _| E^s L]NO
ditional Technology Cost $
Total Energy Consumed Megajoules — I
missions to Atmosphere tons |CO2 I
Safety / Accident Risk lost hours __\
Total pumping rate - Containment
Plume volume
Total pumping rate - Remediatior
Total pumping rate - initial estimate
Number of wells per acre
Plume area
Number of wells
Per well pump rate
Adjusted per well pump rate
Adjusted total pump rate
Length ofmanifold
Treatment method
Beginning plume mass
Operating time
Pore volumes recoverec
Concentration reduction factor
Adjusted CRF
Ending plume mass
450.
1437,500,000.
450.
0.05
1200
60.
7.5
450
0.
Carbon
^^^^^^^^^
8,320.
3.4
1.
gpm Containm
width * H
conversio
ft3 Remed a
gpm Plume vo
gpm
acres
# Number c
gpm Initial est
gpm Adjust for
gpm Re-calcu
ft Length of
wells * M
Treatmen
than 1 me
stripper is
above.
kg Beginn nc
Aquifer th
hrs/yr Operating
# Pore vo u
origma p
con centra
CRF = (-C
1.3367*
systems,
kg Ending p
on origins
starting a
ent pumping rate (capture zone equation): Maximum plume
draulic conductivity * Aquifer thickness * Gradient * 2 * unit
ns.
on pumping rate (assumes 1 pore volume per year): Total
ume for all zones * unit conversions.
wells: Number of wells per acre * Number of acres
mated total pump rate / number ofwells
pump sizes
ated based on number ofwells * adjusted per well pump rate
PVC for manifold: Total ength of each zone + Number of
wimum plume width /4
method entered above. If maximum concentrations is less
l/L, then activated carbon is the default value. Otherwise, air
selected. This default va ue can be modified in the summary
plume mass: The sum of each zone of Area of Doughnut*
ckness & porosity * representative concentration * unit
ns.
time: the hours per year the system is in operation .
mes recovered: Pump rate * Duration * unit conversions /
ume volume. This factor is used to calculate the
tion reduction factor (CRF): If pore volumes recovered < 3,
.2195* PVr) + 1 . If pore volumes recovered >=3, CRF =
3Vr A(-1 .2424). Minimum CRF = 0.05. For Containment
CRF= 1.
time mass: See PlumeCalcs worksheet for calculation based
plume dimensions and CRF. For Containment systems, the
id ending mass is assumed to be the same.
Length of PVC per well
Additional PVC pipe
Length of PVC for manifold (from above)
Conversion factor
PVC
0.
0.
2.03
ft Length of PVC per well: default value is depth to groundwater + aquifer thickness.
ft Additional PVC pipe: optional amount of PVC in the Pump and Treat system.
ft
Ibsffi
Ibs Amount of PVC: [PVC per well * number of wells + additional
PVC pipe + PVC for manifold] * conversion factor. This value is
calculated for Capital or both Capital and O&M projects.
Length of Steel Pipe per wel
Conversion factor
Other steel per wel
Other steel (system-wide, eg, treatment systerr
Steel
10.79
0.
0.
it/well Length of steel pipe per well includes well screen.
Ibs/ft Conversion factor for weight of steel pipe.
Ibs Other steel per well ncludes equipment such as pumps.
Ibs Other steel for system includes weight of air stripper or carbon tanks.
Ibs Amount of steel: [Steel pipe perwell * number ofwells*
conversion factor + Other steel per well * number of wells +
other system components]. This value is calculated for Capital
or both Capital and O&M projects.
Operating time
Average concentration
K parameter
1/n parameter
Activated carbon
Power requirements
Operating time
Electricity
8,320.
0.0001
28.
0.62
46.
300.
8,320.
hrs/yr Amount of activated carton, if required by treatment system, is
mg/L based on average concentration in recovered groundwater (a
function of pump rate, operating time and duration), and
contaminant-specific parameters from Dobbs and Cohen, 1980.
Ibs This va ue is calculated for O&M and both Capital and O&M
projects
kWperhr Amount of electricity over project lifetime: Power requirements
hrs/yr * Operating time in hours / year * Duration (input above). This
kWh value is
;alculated for O&M and both Capital and O&M projects.
-------
Linear feet for tren chine
Trenching rate
Trenching fuel consumption rate
Fuel for trenching
Linear feet for drillinc
Drilling rate
Drilling fuel consumption rate
Fuel for drillinc
Total fuel (diesel; capital phase
Vehicle mileage (transportation for activated carbon disposa
Miles traveled for activated carbon disposal (O&M
Diesel (O&M phase)
Jet fuel use rate per passenget
Weight of passenger + luggage
Total air miles (all passengers; input above
Jet fuel (capital phase
Jet fuel (O&M phase)
Vehicle mileage (travel
Miles traveled (capital
Gasoline (capital
Vehicle mileage (travel
Miles traveled (O&M
Gasoline (O&M phase)
Total fuel (gasoline +jet fuel) - Capital phase
Total fuel (gasoline +jet fuel) - O&M phase
Natural gas requirements for PT/Therm Ox
Operation Time
Natural gas flow rate
Natural gas for Therm Ox
Natural gas requirements for Activated Carbon regeneratior
Conversion factor
Natural gas for activated carbor
Natural gas used for metrics (Therm Ox or Activated Carbon
0. ft
300. ft/hr
0. gaffhr
0. gal
0. ft
1 00. ft/day
0. gal/day
0. gal
gal
5. mpg
0. miles (project total)
0. gal
0.0000097 gal/mi
200. Ibs
miles
0. gal
0. gal
15. mpg
0. miles
0. gal
15. mpg
440,000. miles
29,334. gal
gal
gal
8,320. hrs/yr
2.21 scfm
0. mcf
2 \btu/lb activated carbon
\rncf
0. \rncf
Amount of diesel is based on the amount of fuel for trenching
plus drilling. Diesel is calculated for Capital and both Capital
and O&M projects.
Diesel for O&M is calculated based on transport for activated carbon.
Total jet fuel: Jet fuel use rate* weight* air miles input above.
The default calculation assumes 50% is used in capital, and
50% used in O&M phases.
If treatment method is Air Stripper/Therm Ox, amount of natural
gas: Natural gas flow rate * Duration (input above) * Operation
time in hours per year * unit conversions.
If treatment method is Activated Carbon, amount of natural gas:
Amount of activated carbon (calculated above) * conversion
factor.
Natural gas is used in metrics calculations for O&M and both
Capital and O&M projects.
Metrics - Baseline Calculations
Technology Cost
Volume recoverec
Technology Cost (Capital;
Technology Cost (O&M)
Technology Cost (O&M)
220,000. 1,000 gal/yr
4,100,000. $
680,000. $/year
34,000,000. $ over project
Capital and O&M Costs are based on site data from USEPA
2001 . Capital cost = [277189 * Volume A (-0.781)] * Volume.
Annual O&M cost = [40500 * Volume A (-0.7706)] * Volume.
Energy Cost - Modify usage in Materials and Consumables (above). Update costs on Conversion tab.
Safety/Accident Risk
Hours worked (Capital)
Vehicle speec
Hours worked (O&M)
Total hours workec
Injuries per hour
Vehicle miles traveled (Capital
Vehicle miles traveled (O&M
Total vehicle miles travelec
Injuries per mile
Lost hours per injury
Safety/Accident Risk
26,000. hrs
40. mph
660,000. hrs
686,000. hrs
2.74E-09 injuries/hr
0. miles
440,000. miles
440,000. miles
9.1 OE-07 injuries/mi
48. hrs/injury
lost hours
Safety/Accident Risk: (Statistical number of injuries from time
worked + injuries from miles traveled) * lost hours per injury.
-------
SRT Input, Slurry Wall
Design for Managing Groundwater
:rojectteam (total miles fc
Original Plume After Project
I—H Results I
J
Materials and Consumable Amounts Used for Metrics
Technology Cost
Project-specific Metrics (Add S. Subtract/Offsets! J [
Wall length divided by tr
-------
Energy Cost- Energy usage can be modified in Materials ,
Safety/Accident Risk
-------
SRT Input, Reduced Pump&Treat
1
1
Design for Managing Groundwater
Airline miles flown by project team (total miles for all traveler;
Average Distance Traveled by Site Workers per one-way tri|
Trips by Site Workers during construction
Trips by Site Workers after constructor
Remediation Design (Purpose)
Duration (must be <1 00 years)
Total pumping rate
Tier 2 Change
Calculated Values Number of wells
(dark9raybOX9S| Length ofmanifold
Treatment Method
Beginning Plume Mass
Ending Plume Mass
Original Plume
Plume Area
Plume Length
Plume Volume
i
5
0
49500
miles over proj lifetime
miles one-way
# over project lifetime ,
# over project lifetime
Containment ,| _|
75
I I
Activated Carbon ••
acres
feet
million gallons
kg
years I
gpm
I
] J
kg
kg
After Project
feef
mil gals Ad
C02E
= Use this default value or override with - .-.^n
Restore Defaults
jy Pump & Treat
]^j— -I U |nput I », 17 Enhanced Bioremedialion _ »| Resu\ts \
17 In Situ Chemical Oxidation ' '
I7PRB
17 LTM/MMA ••
Materials and Consumable Amounts Used for Metrics
PVC As
Steel Ibs
Activated carbon Ibs
Electricity kWh
Diesel (CapitalJ gal
Diesel (O&M) gal
Gasoline (Capital) gal
Gasoline (O&M) gal
Natural gas| \rncf
Technology Cost
Project-specific Metrics (Add & Subtract/Offsets)? _| E^s L]NO
ditional Technology Cost $
Total Energy Consumed Megajoules — 1
missions to Atmosphere tons |CO2 1
Safety / Accident Risk lost hours __\
Total pumping rate - Containment
Plume volume
Total pumping rate - Remediatior
Total pumping rate - initial estimate
Number of wells per acre
Plume area
Number of wells
Per well pump rate
Adjusted per well pump rate
Adjusted total pump rate
Length ofmanifold
Treatment method
Beginning plume mass
Operating time
Pore volumes recoverec
Concentration reduction factor
Adjusted CRF
Ending plume mass
450.
1437,500,000.
450.
0.05
1200
60.
7.5
450
0.
Carbon
^^^^^^^^^
8,320.
5.1
1.
gpm Containm
width * H
conversio
ft3 Remed a
gpm Plume vo
gpm
acres
# Number c
gpm Initial est
gpm Adjust for
gpm Re-calcu
ft Length of
wells * M
Treatmen
than 1 me
stripper is
above.
kg Beginn nc
Aquifer th
hrs/yr Operating
# Pore vo u
origma p
con centra
CRF = (-C
1.3367*
systems,
kg Ending p
on origins
starting a
ent pumping rate (capture zone equation): Maximum plume
draulic conductivity * Aquifer thickness * Gradient * 2 * unit
ns.
on pumping rate (assumes 1 pore volume per year): Total
ume for all zones * unit conversions.
wells: Number of wells per acre * Number of acres
mated total pump rate / number ofwells
pump sizes
ated based on number ofwells * adjusted per well pump rate
PVC for manifold: Total ength of each zone + Number of
wimum plume width /4
method entered above. If maximum concentrations is less
l/L, then activated carbon is the default value. Otherwise, air
selected. This default va ue can be modified in the summary
plume mass: The sum of each zone of Area of Doughnut*
ckness & porosity * representative concentration * unit
ns.
time: the hours per year the system is in operation .
mes recovered: Pump rate * Duration * unit conversions /
ume volume. This factor is used to calculate the
tion reduction factor (CRF): If pore volumes recovered < 3,
.2195* PVr) + 1 . If pore volumes recovered >=3, CRF =
3Vr A(-1 .2424). Minimum CRF = 0.05. For Containment
CRF= 1.
time mass: See PlumeCalcs worksheet for calculation based
plume dimensions and CRF. For Containment systems, the
id ending mass is assumed to be the same.
Length of PVC per well
Additional PVC pipe
Length of PVC for manifold (from above)
Conversion factor
PVC
0.
0.
2.03
ft Length of PVC per well: default value is depth to groundwater + aquifer thickness.
ft Additional PVC pipe: optional amount of PVC in the Pump and Treat system.
ft
Ibsffi
Ibs Amount of PVC: [PVC per well * number of wells + additional
PVC pipe + PVC for manifold] * conversion factor. This value is
calculated for Capital or both Capital and O&M projects.
Length of Steel Pipe per wel
Conversion factor
Other steel per wel
Other steel (system-wide, eg, treatment systerr
Steel
10.79
0.
0.
it/well Length of steel pipe per well includes well screen.
Ibs/ft Conversion factor for weight of steel pipe.
Ibs Other steel per well ncludes equipment such as pumps.
Ibs Other steel for system includes weight of air stripper or carbon tanks.
Ibs Amount of steel: [Steel pipe perwell * number ofwells*
conversion factor + Other steel per well * number of wells +
other system components]. This value is calculated for Capital
or both Capital and O&M projects.
Operating time
Average concentration
K parameter
1/n parameter
Activated carbon
Power requirements
Operating time
Electricity
8,320.
0.0001
28.
0.62
50.
8,320.
hrs/yr Amount of activated carton, if required by treatment system, is
mg/L based on average concentration in recovered groundwater (a
function of pump rate, operating time and duration), and
contaminant-specific parameters from Dobbs and Cohen, 1980.
Ibs This va ue is calculated for O&M and both Capital and O&M
projects
kWperhr Amount of electricity over project lifetime: Power requirements
hrs/yr * Operating time in hours / year * Duration (input above). This
kWh value is
;alculated for O&M and both Capital and O&M projects.
-------
Linear feet for tren chine
Trenching rate
Trenching fuel consumption rate
Fuel for trenching
Linear feet for drillinc
Drilling rate
Drilling fuel consumption rate
Fuel for drillinc
Total fuel (diesel; capital phase
Vehicle mileage (transportation for activated carbon disposa
Miles traveled for activated carbon disposal (O&M
Diesel (O&M phase)
Jet fuel use rate per passenget
Weight of passenger + luggage
Total air miles (all passengers; input above
Jet fuel (capital phase
Jet fuel (O&M phase)
Vehicle mileage (travel
Miles traveled (capital
Gasoline (capital
Vehicle mileage (travel
Miles traveled (O&M
Gasoline (O&M phase)
Total fuel (gasoline +jet fuel) - Capital phase
Total fuel (gasoline +jet fuel) - O&M phase
Natural gas requirements for PT/Therm Ox
Operation Time
Natural gas flow rate
Natural gas for Therm Ox
Natural gas requirements for Activated Carbon regeneratior
Conversion factor
Natural gas for activated carbor
Natural gas used for metrics (Therm Ox or Activated Carbon
0. ft
300. ft/hr
0. gaffhr
0. gal
0. ft
1 00. ft/day
0. gal/day
0. gal
gal
5. mpg
0. miles (project total)
0. gal
0.0000097 gal/mi
200. Ibs
miles
0. gal
0. gal
15. mpg
0. miles
0. gal
15. mpg
500,000. miles
33,334. gal
gal
gal
8,320. hrs/yr
2.21 scfm
0. mcf
2 \btu/lb activated carbon
\rncf
0. \rncf
Amount of diesel is based on the amount of fuel for trenching
plus drilling. Diesel is calculated for Capital and both Capital
and O&M projects.
Diesel for O&M is calculated based on transport for activated carbon.
Total jet fuel: Jet fuel use rate* weight* air miles input above.
The default calculation assumes 50% is used in capital, and
50% used in O&M phases.
If treatment method is Air Stripper/Therm Ox, amount of natural
gas: Natural gas flow rate * Duration (input above) * Operation
time in hours per year * unit conversions.
If treatment method is Activated Carbon, amount of natural gas:
Amount of activated carbon (calculated above) * conversion
factor.
Natural gas is used in metrics calculations for O&M and both
Capital and O&M projects.
Metrics - Baseline Calculations
Technology Cost
Volume recoverec
Technology Cost (Capital;
Technology Cost (O&M)
Technology Cost (O&M)
220,000. 1,000 gal/yr
4,100,000. $
680,000. $/year
51,000,000. $ over project
Capital and O&M Costs are based on site data from USEPA
2001 . Capital cost = [277189 * Volume A (-0.781)] * Volume.
Annual O&M cost = [40500 * Volume A (-0.7706)] * Volume.
Energy Cost - Modify usage in Materials and Consumables (above). Update costs on Conversion tab.
Safety/Accident Risk
Hours worked (Capital)
Vehicle speec
Hours worked (O&M)
Total hours workec
Injuries per hour
Vehicle miles traveled (Capital
Vehicle miles traveled (O&M
Total vehicle miles travelec
Injuries per mile
Lost hours per injury
Safety/Accident Risk
26,000. hrs
40. mph
830,000. hrs
856,000. hrs
2.74E-09 injuries/hr
0. miles
500,000. miles
500,000. miles
9.1 OE-07 injuries/mi
48. hrs/injury
lost hours
Safety/Accident Risk: (Statistical number of injuries from time
worked + injuries from miles traveled) * lost hours per injury.
-------
SRT Input, Tailings Relocation by Excavation and Truck
1
Design for Mane
Airline miles flown by pr
Average Distance Tra
Trir.
T
Tier 2: Change
Calculated Values
(dark gray cells)
ging Soil
ject team (total miles for all travelers)
eled by Site Workers per one-way trip
s by Site Workers during construction
ips by Site Workers after construction
Distance to Disposal (one-way)
Type of Disposa
Volume of affected soil
Volume of affected soil
Total hours to excavate
Number of loads for disposa
Total miles driven for disposa
Total hours for fill dirt placement
Number of loads of fill dirt
Total miles driven for fill
5
20000
0
20
miles over proj lifetime
miles one-way
# over project lifetime ,
# over project lifetime —
Hazardous ^J |
^
person-hours
t
miles
hours
#
mites _l
C
se is e au va ue orovem ewi
^^Kfl ^^^^
Technology Design ^^jp»«*j
Main 1 — H Input 1 1* — H Results!
W Soil Vapor Be traction ' '
Therma [^J Q
Materials and Consumable Amounts used for Metrics
Technology Cost
O&M| \$
Project-specific Metrics (Add & Subtract/Offsets) _| Eves
Additional Technology Cost $
Total Energy Consumed Megajoules |
O2 Emissions to Atmosphere tons _|CO 2 _|
Safety / Accident Risk lost hours _|
CNO
Area of Affected Soil
Total Thickness of Affected Soil
Volume of affected soil
Volume of affected soil
Soil density
Excavation rate
Total hours to excavate
Fluff factor (excavated soil)
Dump truck volume for disposal
Number of loads for disposa
Total miles driven for disposal
Fluff factor (fill)
Dump truck volume for moving fil
Number of loads of fill dirt
Fill spread rate
Water compaction rate
Spread/compaction rate
Total hours for fill dirt placement
Distance from site to fill source (one way)
Total miles driven for fill
8,000,000.
100.
95.
53.
1.3
12.
130,000,000.
0.4
12.
990,000.
448.5
174.3
654.
10.
ft2 Volume o affected soil: Area * (Depth to Bottom - Depth to Top of
ft Affected Soil).
13
cuyd
Ib/ft3 Tot
tons/hr ton
person-hours
Loa
cuyd
# loads
miles Tot
Loa
cuyd
# loads
cu yd/hr Tot
cu yd/hr yd3
cu yd/hr con
hrs
al hours to excavate: Volume of affected soil * soil density * (1
/2000 Ibs) * (1/rate of excavation in ton/hr).
ds for disposal: Volume of affected soil * fluff factor * (1/dump truck volume) * (1 yd3/27 ft3 unit conversion).
al miles driven for disposal: Number of loads for disposal * 2 * Distance to disposal (input above).
ds of fill dirt: Volume of affected soil (above) 'fluff factor* (1/dump truck volume) * (1 yd3/27ft3).
al hours for fill dirt placement, s the sum of: (1) Area (user input) * (1 yd2 / 9 ft2) / fill spread rate in
/hr. (2) Number of loads of fill drt (calculated above) * dump truck volume (above) /rate of water
paction in yd3/hr. (3) Total volume of fill dirt / spread & compaction rate in yd3/hr.
miles Total miles driven for fill: Number of loads of fill dirt * 2 * Distance from site to fill source.
mile,
Total
Excavator fuel consumption rate
Dump truck fuel use rate
Total fijel (diesel)
Jet fuel use rate per passenger
Weight of passenger + luggage
air miles (all passengers; input above
Total jet fuel
Vehicle Mileage
Total fijel (gasoline + jet fijel)
3.
8.
0.0000097
200.
0.
15.
gal/hr Tot
mpg con
gals foe
al diese : (Total hours to excavate & place fill * Excavator fuel
sumption rate) + (Total miles driven for disposal * Dump truck
use rate)
gal/mi Total jet fuel: Jet fuel use rate* we ght * air miles input above.
Ihs
gal
mpg Tot
gal fror
al gasoline: (Construction + Postconstruction trips) * 2 * distance
n office to site / vehicle mileage
(These calculations do not include Project-specific, d rect addit ons / subtractions)
Hour
Technology Cost
Unit Cost (hazardous)
Volume
Fluff Factor (excavated soil)
Technology Cost
Energy COSt - Energy usage can
Safety/Accident Risk
Hours worked
Vehicle Speed
for travel (post- con struct! on /site visit)
Total hours worked
Injuries per hour
Total vehicle miles traveled
Injuries per mile
Lost hours per injury
Safety/Accident Risk
400.
16,000,000,000.
$/cu yd Tec
fluff
cuyd exc
exp
$
hnology cost is based on unit costs for disposal as hazardous waste (excavated volume *
* unit cost). For non-hazardous, costs are derived from RACER (Cost = (88.59 *
avated volume * fluff) + 4007). For excavation, all costs are assumed to be capital costs,
ended within the first year.
be modified in Materials and Consumables (above). Update costs on Conversion tab.
840,000.
40.
0.
840,000.
2.74E-09
150,200,000.
9.10E-07
48.
hrs Safety/Ace dent Risk: (Statistica number of injuries from time
mph worked + njuries from miles traveled) * lost hours per in ury.
hrs
hrs
injuries/hr
miles
injuries/mi
hrs/injury
lost hours
-------
SRT Output, Current Pump&Treat and Slurry Wall
Non-normalized
Calculations in natural units
Carbon Dioxide Emissions to Atmosphere |
Enhanced Bio. | |
ISCO| |
PRB| |
*: SeeSRTv.2 Known Issu
Normalize?
s
CYes ENo
structions:
-Enter your data here
-Calculated value You can
ot change this
NO/
f ons NO x
J
SOK
tons SO x
PM10
tons PM 10
Total EnergyjrGrpjtjSj
Megajoules
[Main "1"
— nlnputl H Technology Design | — '
cs to see more, go back to Inputs to adjust and
^^^3 ^^5
1 Result/"]
IJ.njlreda |0 Mam (ft
kWh
^^^^^^^^^^^^^^^^^^j^^|
rTier1/2orSoil),orExit Cost | NPV |
dollars per Ib dissolved
dollars ^
mass
Safety /Accident Risk _|
lost hours injury risk
^^^^^ i
i
i
Change in Resource S
million gal |
1
1
1
i
SRT
-------
SRT Output, Reduced Pump&Treat and Slurry Wall
Non-normalized
Calculations in natural units
Carbon Dioxide Emissions to Atmosphere |
Enhanced Bio. | |
ISCO| |
PRB| |
*: SeeSRTv.2 Known Issu
Normalize?
s
CYes ENo
structions:
-Enter your data here
-Calculated value You can
ot change this
NO/
f ons NO x
J
SOK
tons SO x
PM10
tons PM 10
Total EnergyjrGrpjtjSj
Megajoules
[Main "1"
— nlnputl H Technology Design | — '
cs to see more, go back to Inputs to adjust and
^^^3 ^^5
1 Result/"]
IJ.njlreda |0 Mam (ft
kWh
^^^^^^^^^^^^^^^^^^j^^|
rTier1/2orSoil),orExit Cost | NPV |
dollars per Ib dissolved
dollars ^
mass
Safety /Accident Risk _|
lost hours injury risk
^^^^^ i
i
i
Change in Resource S
million gal |
1
1
1
i
SRT
-------
SRT Output, Tailings Relocation by Excavation and Truck
Technology Design | >\ Results 1
Non-normalized
Calculations in natural units
Carbon Dioxide Emissions to Atmosphere
tons CO 2 | Ibs CO 2 perlb contam
Therm al|_
NOX*
tons I\IOX
SOX
tons SOx
PM10
tons PMIO
Total Energy Consumed
Megajoutes kWh
Technology Cost |
dollars dollars per Ib contar.
*: See SRTv.2 Known IE
alize? | r
Yes K HO
SRT
-------
APPENDIX D - EVAPORATION CALCULATIONS
Final 12/23/10
-------
Calculations of Evaporation Pond Capacities Necessary for Disposal of Treated and
Collected Water Assuming Different Active Evaporation Spraying Scenarios
Conditions for the different active evaporation spraying scenarios were based on the
volumes of water, both treated and untreated, calculated for the proposed pump and treat
conditions assuming flushing of the Tailings Piles had ceased and the piles were being
dewatered. Both the estimated volumes and concentrations were first checked against the
current pump and treat system to ensure that the current treatment system could handle
the proposed flows, contaminant concentrations, and water quality conditions. Table 1
indicates the current inlet flows, contaminant, and water quality conditions being
observed at Homestake. Table 2 contains comparable information for the proposed
pumping conditions. Table 3 compares the two sets of operating conditions. The inlet
contaminant and water quality concentrations in the proposed pumping conditions are
similar to those in the current treatment plant so it is expected that the current treatment
system will be adequate in this regard. The proposed conditions involve a slightly higher
flow rate of 450 gpm than the current pumping operations.. Homestake has indicated that
the current treatment system can achieve at least a sustained flow rate of 540 gpm
(Homestake, 2010), which indicates that the proposed flowrate is within the capacity of
the current treatment system. It was concluded then that the current treatment system was
adequate to handle both the proposed scenario and also for continued operation under the
current conditions.
Table 1 Current Treatment Plant Operating Conditions (information s
by Homestake from a pilot test using both RO treatment columns, Se
Date
9/22/2009
9/28/2009
Total
GW
404
437
Flow to
Clarifier
Flow to
RO
RO
injection
flow
Product out
Brine out
Gpm
418
437
405
429
272
294
308
323
98
106
upplied
pt 2009)
Ratio Brine/
Product
0.24138
0.24709
Average treatment feed values for current system (averaged over 2001-9, 2008 Homestake Annual
Monitoring report and associated data from Homestake Access data base)
IDS
clarifier
5800
ppm
U clarifier
13.4 mg/L
RO/
deep
aquifer
IDS
260
ppm
URO
+deep
aquifer
0.031
mg/L
Se clarifier
1.3 mg/L
SeRO+
deep
aquifer
0.01 4 mg/L
Moly
clarifier
17.4 mg/L
Moly
RO+deep
aquifer
0.08mg/L
Note: Deep aquifer water is added to the RO product water before reinjection
-------
Table 2 Treatment Plant Operation Conditions for Proposed Pump
and Treat Scenario (Note 1)
Source
Tailings
SW line
(LTP)
STP
Lline
Total or
avg in
feed to
RO
Rate
(gpm)
65
250
150
50
450
To
Ponds
RO
RO
RO
TDS
(ppm)
>5000
2400-
7000
1100-
4000
700-
1100
TDS
Avg
4700
2550
900
3561
U(ppm)
>10 ppm
2-10
2-16
0.2-0.5
UAvg
6.0
10.0
0.4
6.7
Se
(pm)
0.3-0.6
0.5-3
1-4
0.8
Se
Avg
0.45
1.6
2.5
0.8
1.8
Moly
(ppm)
Note 2
50
10
1.5
1
Moly
Avg
50
10
1.5
1
6.2
Note 1: flows are intended to be conservative and may overestimate those necessary to contain plume
Table 3 Comparison of Average Flow Rates and Species Concentrations
for Current and Proposed Treatment Systems Feed
Inlet
Current
Inlet
Proposed
TDS
(ppm)
5800
3600
U
(mg/L)
13.4
6.7
Se
(mg/L)
1.3
1.8
Moly
(mg/L
17.4
6.2
Flow rate (gpm)
415
450
(avg late Sept
2009, both RO
columns operating)
Disposal of the waste streams from the current and proposed pump and treat conditions
were then used with different passive and active evaporation spraying scenarios to
calculate the evaporation pond capacity necessary for each scenario.
The three scenarios for which calculations of evaporative pond capacities and
corresponding pond surface areas were performed are the following:
1) Current active evaporative spray system with a) proposed and b) current systems
2) Active evaporation only on the proposed new pond under proposed conditions
3) Passive evaporation only on all ponds (existing and new proposed pond)
Calculations for the latter two scenarios were developed only for the proposed pumping
conditions since that requires higher evaporative capacity; therefore, the pond areas
calculated would also be sufficient for the current scenario. It is noted that a range of
scenarios could be developed with different amounts of active evaporative spraying so
these scenarios are only examples. Also, it was assumed in all the evaporation scenarios
that the current treatment plant would not be augmented by additional treatment capacity,
i.e. another high pressure RO unit or additional waste treatment through TDS reduction
outside the current treatment plant. Additional treatment, which could lower the disposal
-------
demand on the ponds through lower waste generation, should be considered along with
changes in active evaporation spraying and/or increases in the evaporation pond capacity.
Overall optimization combinations are discussed more at the end of this section.
Table 4 shows the evaporative capacity needed for the current pumping. Table 5 shows
the evaporative capacity needed for the proposed pumping conditions. The evaporative
capacity of the existing ponds and the capacity of the existing ponds plus the proposed
third pond (additional surface area of 30 acres) are both included in Table 6. The
volumetric holding capacity of the ponds was not considered (i.e., the ponds' capacity to
accept water only considered long-term evaporation, and not the volume to fill the
ponds). Information provided verbally by Homestake indicates that the current ponds are
near volumetric capacity.
Comparison of the current rate of waste discharge to the ponds and the current pond
evaporation capacity indicates that under the current conditions, nearly all the
evaporation capacity, both passive and active, of the existing evaporation pond system is
being used. Comparison of the waste generation under the proposed pumping and
treatment conditions indicates that discharge to the ponds would exceed the existing pond
evaporative capacity for all the evaporative spraying scenarios (Table 7). For use of the
current capacity of evaporative spraying at the existing ponds, approximately 11 acres of
additional passive (non-spraying) evaporation pond surface area would need to be added
for the proposed pumping conditions. If the same rate of evaporation spraying currently
observed for the current ponds is used on an additional pond (but ceased on the existing
ponds), an additional pond acreage of approximately 36 acres would be necessary. If no
evaporation spraying was used on any of the ponds, a pond with approximately 52 acres
of surface area would need to be added.
Table 4 Liquid to ponds, current pumping conditions
Operating information from Sept 2009 pilot running both
system operation, from Homestake 2008 Operating report
Source
Treatment Plant (assume 25% of feed)
Tailings Collection (direct to ponds)
Toe Drain Collection (direct to ponds)
Precipitation existing ponds (1 0 in/yr*
83ft/year*43 acres*43560sq ft/acre* 1 year/365 days*1
day/1440 min*7.48 =22 gpm)
Precipitation existing +30 acre new pond (1 0 in/yr*
83ft/year*73 acres*43560sq ft/acre* 1 year/365 days*1
day/1440 min*7.48 =37 gpm)
Total liquid to existing ponds, including precipitation
Total liquid to existing ponds and 30-acre additional pond,
including precipitation
Feed
Vol rate
(gpm)
240
Vol rate
(gpm)
60
50
11
22
37
143
158
-------
Table 5 Liquid to ponds, proposed pumping scenario
Assume 25% brine and blow-down -avg over
treatment system operation, from Homestatke 2008
Operating report
Source
Treatment Plant
Tailings/Toe Collection (direct to ponds)
Precipitation existing ponds (1 0 in/yr*
83ft/year*43 acres*43560sq ft/acre* 1 year/365
days*1 day/1440 min*7.48 =22 gpm)
Precipitation (1 0 in/year) existing +30 acre new
pond (1 0 in/yr*
83ft/year*43 acres*43560sq ft/acre* 1 year/365
days*1 day/1440 min*7.48 =37 gpm)
Total liquid to existing ponds, including precipitation
Total liquid to existing ponds and 30-acre additional
pond, including precipitation
Feed
Vol
rate
(gpm)
450
Vol rate
(assume
25% of
feed)
(gpm)
112.5
65
22
37
199.5
215
Table 6 Evaporative Capacity of Ponds
Present Pond evaporative capacity without evaporation sprayers
(Homestake, 2010)
Present Pond evaporative capacity with evaporative sprayers
(Homestake, 2010)
Proposed pond (30 acres) with only passive evaporative capacity
Proposed pond evaporative capacity with evaporative sprayers (30
acres )
Total evaporation, existing + proposed ponds, capacity w/o
evaporative sprayers
Total evaporation capacity with evaporative sprayers only on
proposed pond
Total evaporation, existing ponds with evaporative sprayers,
passive evaporation only on proposed 30-acrea pond
Total evaporation, existing + proposed ponds, capacity with
evaporative sprayers
(gpm)
80
160
55.81
111.63
135.81
191.63
215.81
271.63
Table 7 Shortfalls in Evaporative Pond Capacity and Pond Additional Areas Needed
Liquid capacity shortfall existing ponds, current pond/evaporation, proposed conditions
Liquid capacity shortfall, existing ponds, active evaporation only 3rd pond, 30 acres
surface area assumed, proposed conditions
Liquid capacity shortfall existing ponds, no active evaporation, proposed conditions
Pond area necessary (with current active spraying) to augment current ponds
Area of proposed pond if evaporative spraying used only on 3rd pond
Area of proposed pond, no evaporative spraying any ponds
40 gpm
23 gpm
97 gpm
11 acres
36 acres
52 acres
-------
Combination of Evaporative Capacity with other Waste Minimization Optimizations
The shortfall of evaporative capacity and volume of liquid to the evaporation ponds under
the proposed pumping conditions, assuming continuation of the existing evaporative
spraying system, is approximately 40gpm. This shortfall could be reduced by additional
pond capacity or by reduction of liquid load. The latter could be achieved by the
following:
1. Treatment of the majority of the toe and tailings water. Currently, Homestake is
collecting -61 gpm of toe/tailings water. Under the proposed pumping conditions
65 gpm would be collected. Assuming the current treatment efficiency (75%
product, 25% brine/blowdown), the loading to the ponds could be reduced by
nearly the capacity shortfall if the toe/tailings water under the current and
proposed conditions was treated. The sustainable treatment flow rate is at least
540 gpm (Homestake 2010), with the increased feed flow rate (480 - 500 gpm) d
still achieveable within the current treatment system. However, as both the
contaminant concentrations and the salt concentrations in the feed would be
higher than those currently being treated, pilots for additional toe/tailings
treatment would need to be performed to determine if the contaminants are treated
to acceptable levels and the pretreatment adequate for system operation.
2. Addition of a second high pressure RO unit to the current RO system. The current
high pressure RO unit extracts approximately 40 gpm of product following
extraction by one of the low pressure RO units. Assuming that addition of a
second high pressure RO column would have similar extraction efficiency, a
second high pressure RO unit would also potentially address nearly all of the
capacity shortfall.
-------
APPENDIX E - EVAPORATIVE SPRAYING EQUIPMENT INFORMATION
Final 12/23/10
-------
TO: Dave Becker, RSE Team
FROM: Paul Robinson
DATE: March 18, 2010
SUBJECT: Evaporation Rate Materials
TURBOMISTER - a supplier of spray evaporation equipment used at Evaporation Pond
1 at the HMC site has a wide range of material on the theory and practice of spray
evaporation.
An overview of spray evaporation rate considerations, including droplet size, evaporator
through put and other factors is at:
http://www.turbomister.com/turbomist-evap-rates.php
An evaporation efficiency conversion chart relating pan evaporation achieved in inches
per month to volume of pond circulated through the evaporators is at:
http://www.turbomister.com/PDFs/Efficiency%20conversion%20Table%20Turbomist.pd
f - copy attached
A technical paper addressing evaporation theory and practice including consideration of
spray fallback factor in spray evaporation rate evaluation is at:
http://www3.interscience.wilev.eom/i ournal/112475413/abstract?CRETRY=l&SRETRY
K) - copy attached
Gregory P. Flach, Frank C. Sappington, and Kenneth L. Dixon, "Field Performance of a
Fan-Driven Spray Evaporator", REMEDIATION, Spring 2006
ABSTRACT
"An emerging evaporation technology uses a powerful axial fan and high-pressure spray
nozzles to propel a fine mist into the atmosphere at high air and water flow rates.
Commercial units have been deployed at several locations in North America and
worldwide since the mid-1990s, typically in arid or semiarid climates. A commercial
spray evaporator was field tested at the U.S. Department of Energy's Savannah River Site
in South Carolina to develop quantitative performance data under relatively humid
conditions. A semi-empirical correlation was developed from eight tests from March
through August 2003. For a spray rate of 250 L/min (66 gpm) and continuous year-round
operation at the Savannah River Site, the predicted average evaporation rate is 48 L/min
(13 gpm)." © 2006 Washington Savannah River Company*
-------
SLIMLINE WHWACJimiHG LTD.
CONVERSION TABLE FROM NET PAN EVAPORATION TO TURBOMIST
EFFICIENCY ESTIMATES FOR THE TURBOMIST S30P EVAPORATOR
This chart is indicated in inches per month. If you have annual pan evaporation in feet, convert to inches
And divide the total by 12 months to determine the average pan evaporation rate to use below.
Percentage
of volume
Pumped aloft
This conversion chart is the property of Slimline Manufacturing Ltd an is intended to
give our evaporator custom base a conservative estimate of what our S30P evaporator
models will do at their site, based upon the net pan evaporation provided.
-------
REMEDIATION Spring 2006
Field Performance of a
Fan-Driven Spray Evaporator
Grec[ory_P._Fl_ach
Fra n k^Sagjgiri gto n
Kenneth L. Dixon
An emerging evaporation technology uses a powerful axial fan and high-pressure spray nozzles
to propel a fine mist into the atmosphere at high air and water flow rates. Commercial units have
been deployed at several locations in North America and worldwide since the mid-1990s, typically
in arid or semiarid climates. A commercial spray evaporator was field tested at the U.S.
Department of Energy's Savannah River Site in South Carolina to develop quantitative perfor-
mance data under relatively humid conditions. A semiempirical correlation was developed from
eight tests from March through August 2003. For a spray rate of 250 L/min (66 gpm) and contin-
uous year-round operation at the Savannah River Site, the predicted average evaporation rate is
48 L/min (13 gpm). © 2006 Washington Savannah River Company*
INTRODUCTION
Evaporation provides one mechanism for reducing the volume of wastewater, a com-
mon component of an overall wastewater management strategy. Example applications
include mining, distillation and textile plants, animal waste disposal, phosphate fertil-
izer production, and landfill management. Evaporation also has application to
groundwater remediation. For example, the Savannah River Site (SRS) is using phy-
toremediation to reduce the discharge of tritiated groundwater to a stream (Blount
et al., 2002). The remediation project involves capturing a tritium (H-3) plume in a
man-made pond located at the seepline, and spray-irrigating the collected water over
an upgradient mixed pine and deciduous forest. Enhanced evapotranspiration can sig-
nificantly reduce the net flux of tritium discharging to surface water (Blount et al.,
2002). However, evapotranspiration demand is minimal during winter months, and
heavy precipitation in any season significantly increases influx to the collection pond
due to surface runoff. Under these circumstances, the net influx can exceed the
holding capacity of the pond, causing overflow. Thus, a supplemental technology,
such as spray evaporation, was desired to remove excess water from the collection
pond during winter and wet periods.
An emerging evaporation technology uses a powerful axial fan and high-pressure
spray nozzles to propel a fine mist into the atmosphere at high air and water flow rates.
Commercial examples include the Slimline Manufacturing Ltd.Turbo-mist (http://
www.turbomist.com/) and SMI® Super Polecat evaporators (http://www.evapor.com/).
Such evaporators rely on the sensible heat that can be extracted from unsaturated (< 100
percent humidity) air to drive evaporation. Incoming "dry" air is brought into contact with
the spray field through a combination of the mechanical fan and natural wind, and simulta-
© 2006 Washington Savannah River Company. This article is a U.S. government work and, as such, is in the public domain in the United States of America. 97
Published online in Wiley Interscience (www.interscience.wiley.com). DOI: 10.1002/rem.20083
-------
Field Performance of a Fan-Driven Spray Evaporator
When unsaturated air is
brought into contact with
liquid water, with no heat
transfer to or from the
overall system, liquid evap-
orates and air is cooled
until thermodynamic equi-
librium is reached.
neously cooled and humidified through evaporation. Because the energy for evaporation
comes from a natural source, the overall cost is relatively low.
Field performance of these evaporators is affected by a number of factors, including
the flow rate, temperature, and humidity of the air contacting the spray field, and the
spatial distribution, suspension time, and size of spray droplets. Hot, dry, and windy
conditions are most favorable to spray evaporation, and units have been commercially
deployed at several locations in North America and worldwide since the mid-1990s, typ-
ically in arid or semiarid climates. Although anecdotal information and limited field
J o
measurements (Ferguson, 1999) suggest the technology is effective, at least in arid cli-
mates, quantitative performance data under more humid conditions are not available.
Such data were needed to evaluate the technology for application at the SRS tritium
phytoremediation site.
The purpose of this technical note is to provide evaporator performance data for
Southeast U.S. climate conditions, and to present a semiempirical correlation for pre-
dicting evaporation near the range of conditions tested. The field data were acquired at
the U.S. Department of Energy's Savannah River Site near Aiken, South Carolina, from
late March through mid-August 2003. The specific system tested is the Slimline Turbo-
mist evaporator.
EVAPORATION PRINCIPLES
When unsaturated air is brought into contact with liquid water, with no heat transfer to
or from the overall system, liquid evaporates and air is cooled until thermodynamic
equilibrium is reached (100 percent humidity). Such a process is termed adiabatic satu-
ration and is the principle behind swamp coolers used for residential cooling in the
Southwest United States and agricultural cooling (e.g., poultry houses).The energy re-
quired to vaporize liquid water (latent heat of vaporization) is extracted from unsatu-
rated air through cooling (sensible heat). The amount of cooling as a function of the
temperature and relative humidity of the incoming air stream can be determined
through application of the first law of thermodynamics, which states that enthalpy is
conserved in a open system. With minor approximation, the adiabatic saturation process
can be described by:
AX
out
(1)
where h* — enthalpy of moist air per unit mass of dry air, h — enthalpy of dry air, y —
specific humidity or humidity ratio, and hw = enthalpy of water vapor (Reynolds and
Perkins, 1977). The thermodynamic properties of moist air can be readily computed
from an American Society of Heating, Refrigerating, and Air-Conditioning Engineers
J o' o o' o o
(ASHRAE) handbook (e.g., ASHRAE, 1985) or equivalent source.
As an example calculation, the annual average temperature and relative humidity at
the Savannah River Site are 18°C (65°F) and 68 percent, respectively (Hunter &Tatum,
1997). For these conditions, the evaporative cooling achieved when the incoming air
stream is saturated is 3.7°C (6.6°F). Exhibit 1 shows contours of constant evaporative
cooling degrees resulting from various combinations of temperature and relative humid-
ity. The dashed box defines an approximate envelope of likely weather conditions at the
Savannah River Site.
92
© 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem
-------
REMEDIATION Spring 2006
Evaporative cooling, \'i: - 10 8
• Annual
20 40 60 80
Relative hu mid ity(%)
Exhibit 1. Evaporative cooling potential as a function of
temperature and relative humidity
Spray evaporation under atmospheric conditions is expected to be proportional to
the cooling and evaporation amounts computed under adiabatic saturation conditions.
For evaporation to be sustained, air (and water) must be continuously supplied to re-
plenish the system. An energy balance expanding on Eq. (1) indicates that evaporation
of liquid water into unsaturated air is proportional to the mass flow rate of air deliv-
ered to the system. For atmospheric spray evaporation, fresh air is delivered to the
spray field through natural winds. Thus, the spray evaporation rate is also expected to
be proportional to local wind speed. The overall dimensions of the spray field, and the
distribution, suspension time, and size of spray droplets within, are also expected to af-
fect the evaporation rate.
EXPERIMENT DESIGN AND SETUP
In many evaporator applications, water is drawn from a holding pond (e.g., mine tail-
ings) and sprayed into the air. Droplets not evaporated fall back into the pond. At the
Savannah River Site, deployment over dry land was under consideration, leading into
field testing. For this situation, high evaporation with little or no fallback was considered
to be optimal. Therefore, field testing focused on reduced spray rates (20 to 150 L/min)
and smaller droplet sizes compared to that produced by the vendor's default spray noz-
zle configuration (~250 L/min). Ultimately, the evaporator was deployed at the phy-
toremediation collection pond, for which fallback was not a concern.
To measure evaporator performance for a particular nozzle configuration and
weather condition, specialized collection devices were deployed on a grid to measure
spray fallback. The evaporation rate was then computed as the spray rate minus the fall-
back rate. The surveyed grid system is depicted in Exhibit 2, along with an example fall-
back pattern. A 6.1 -m (20-ft) square spacing was chosen near the origin of the grid
where the spray evaporator was located. Collection devices were deployed at a variety of
grid locations to handle particular weather conditions—primarily, wind speed and di-
rection. To handle a wide range of potential fallback amounts over the duration of a field
© 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem
93
-------
Field Performance of a Fan-Driven Spray Evaporator
fallback rate (mm/d)
0,5 5 50
40
20
-20
o o c
-40 -20 ' 6 20 40
meters
Exhibit 2. Grid system defining placement of spray fallback
collection devices, and an example fallback pattern
test, both rain gauges and absorbent pads were used. For each absorbent pad, fallback
was determined from the area, and dry (pre-test) and wet (post-test) weights of the pad.
FIELD TESTING AND DATA
Eight field tests were conducted between March and August 2003 (Flach et al., 2003).
Comparison of the fallback measurements from the absorbent pads and rain gauges from
all tests indicated that the pads are capable of reliably retaining fallback amounts up to
approximately 5 mm (0.2 in) of water, while at least 5 mm (0.2 in) is needed with a rain
gauge to avoid readings that are biased low. Thus, if a rain gauge reading exceeded 5 mm
o o o o o o
at an individual grid location, that value was adopted as the fallback amount. Otherwise,
the absorbent pad measurement was selected. For each test, a map of spray fallback was
created by interpolating the point data from the preferred collection device at each grid
location onto a regular 6.1m (20 ft) X 6.1 m (20 ft) grid using a kriging interpolation
algorithm (Isaaks & Srivastava, 1989). Numerical integration of the kriged surface pro-
duced the total amount of spray fallback for a given test.
Exhibit 3 summarizes the evaporator configuration, average weather conditions, and
spray fallback for each field test. Because testing was conducted from March through
August, periods of rainfall were avoided, and daytime testing was preferred for logistical
reasons, most tests were conducted at relatively warm temperatures and moderate hu-
midity. An exception was the 16-hour overnight test beginning at 4:21 P.M. on March
31 and ending at 8:58 A.M. on April 1, for which the average conditions were 3.5°C
(38.3°F), 72% relative humidity, and 0.85 m/s (1.9 mph) wind speed.These conditions
were unfavorable for evaporation, and the evaporation rate was low.
DATA CORRELATION
Because the collection of test data summarized in Exhibit 3 only defines evaporator
performance under certain specific conditions, a model capable of predicting evapora-
94
© 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem
-------
REMEDIATION Spring 2006
Nozzle configuration
Test date
03/31/03
04/29/03
05/01/03
05/14/03
06/25/03
06/26/03
07/24/03
08/11/03
No.
30
30
30
30
30
27
27
30
Cores
25
25
25
25
25
45
45
45
Orifices
D2
D2
D5
D5
D5
D6
D6
D8
Spray
rate
(L/min)
23
23
59
63
61
96
99
148
Evap.
Weather conditions
rate Temp.
(L/min)
6.9
20
25
22
31
50
43
53
(°C)
4
25
26
22
31
31
29
29
Rel.
hum.
(%)
69
52
56
46
41
46
56
64
Wind
speed
(m/s)
1.3
2.1
3.1
0.9
1.6
2.2
2.0
2.9
Exhibit 3. Summary of evaporator field testing results
tion rates under more arbitrary conditions is desirable. Following the previously stated
expectation that the evaporation rate is largely proportional to the evaporative cooling
potential based on adiabatic saturation and wind speed, the dimensional evaporation
data are first normalized as
E' =
fl-AF-1/
(2)
where £' — normalized evaporation rate, £ — evaporation rate, a — empirical constant,
Ar = evaporative cooling, and V = wind speed.
Similarly, the spray rate is normalized as
Q
Q' =
o-AF-1/
(3)
where Q — normalized spray rate, Q^— spray rate, a — empirical constant, AT — evap-
orative cooling, and V = wind speed.
The evaporation rate is zero when the spray rate is zero. The field data suggest
the evaporation rate increases in proportion to spray rate initially but levels off at
higher spray rates. A nondimensional empirical function capturing this qualitative be-
havior is
1
E' =
(4)
where £' — normalized evaporation rate, b — empirical constant, and Q — normalized
spray rate. The limiting behavior of Eq. (4) is £' —> 0 as Q —> 0, and £' —» 1 as Q —> °°.
In terms of dimensional parameters, Eq. (4) is equivalent to the semiempirical model:
© 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem
95
-------
Field Performance of a Fan-Driven Spray Evaporator
3,0 -
0.5 1.0 1.5 2.0 2.5
Normalized spray rate, Q/(aAT V)
Exhibit 4. Normalized evaporation and spray rates
E =
o-A7"-l/
b
—
Q
(5)
with limits of £ -» 0 as Q^—» 0, and £ -» a • Ar • V as Q_-» oo. Optimal values for the
empirical constants a and b were determined using least-squares parameter fitting, with
the result of a = 1.24 X 10^m2/°C (0.49 gpm/°F - mph) and b = 1.45(unitless).
Normalized evaporation rate is plotted against normalized spray rate in Exhibit 4. The
model is observed to fit the field data reasonably well.
While the functional form given by Eq. (5) incorporates two factors influencing
evaporation, other important parameters (droplet size, residence time, etc.) are not ex-
plicitly considered. The latter influences are implicitly embedded in the empirical con-
stants a and b. Furthermore, limited field data were available to define optimal values and
test the robustness of the selected correlation. Thus, the predictive model is applicable to
the particular commercial system and environmental conditions tested. Extrapolation to
other evaporator models and weather conditions should be done with caution.
The nondimensional predictive model defined by Eq. (4) can be translated into the
equivalent dimensional form given by Eq. (5) for specific weather conditions (i.e., val-
ues of Ar and V). For the default spray rate of 250 L/min (66 gpm) and continuous
year-round operation at the Savannah River Site ( Ar = 3.7°C, V = 2.4 m/s,), the
predicted average evaporation rate is 48 L/min (13 gpm).
96
© 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem
-------
REMEDIATION Spring 2006
COST ANALYSIS
During field experimentation at the Savannah River Site, all power required to operate
the evaporator (axial fan and water pump) was supplied through a single portable diesel
generator. Power usage varied little during and between tests, and averaged 30 kW.
Electricity costs commercial users in the Southeast United States approximately $0.09
per kW-hr. For the projected annual average evaporation rate of 13 gpm, the projected
treatment cost is $3.50 per 1,000 gallons of water evaporated.
ACKNOWLEDGMENTS
The work described in this technical note was performed at the Savannah River
National Laboratory by Westinghouse Savannah River Company LLC for the U.S.
Department of Energy under Contract No. DE-AC09-96SR18500. The authors are
grateful to these institutions for permission to publish their findings and for the sup-
port of Phil Prater, DOE Project Team Lead. We also thank colleagues Susan Bell,
John Bennett, Gerald Blount, and Mo Kasraii for critical program support and tech-
nical assistance.
NOMENCLATURE
a, b = empirical constants
h* = enthalpy of moist air per unit mass of dry air
h = enthalpy of dry air
h = enthalpy of water vapor
£ = evaporation rate
£' = normalized evaporation rate
Q^= spray rate
Q^ = normalized spray rate
V = wind speed
Ar = evaporative cooling potential based on temperature and relative humidity
7 = specific humidity or humidity ratio
REFERENCES
American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). (1985). ASHRAE
handbook: 1985 fundamentals. Atlanta, GA: Author.
Blount, G. C., Caldwell, C. C., Cardoso-Neto, J. E., Conner, K. R., Jannik, G. T., Murphy Jr., C. E., et al.
(2002). The use of natural systems to remediate groundwater: Department of Energy experience at the
Savannah River Site. Remediation, 12(3), 43-61.
Ferguson, R. B. (1999). Management of tailings pond water at the Kettle River Operation. CIM Bulletin,
92(1029), 67-69.
Flach, G. P., Sappington, F. G., & Dixon, K. L. (2003). Field performance of a Slimline Turbomist evaporator
under Southeastern U. S. climate conditions (U). WSRC-RP-2003-00429. Aiken, SC: Westinghouse
Savannah River Company. Retrieved October 7, 2005, from http://sti.srs.gov/fulltext/rp2003429/
rp2003429.pdf
© 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem 97
-------
Field Performance of a Fan-Driven Spray Evaporator
Hunter, C. H., & Tatum, C. P., (1997). Meteorological annual report for 1996 (U). WSRC-TR-97-0214. Aiken,
SC: Westinghouse Savannah River Company. Retrieved October 7, 2005, from http://www.osti.gov/
dublincore/ecd/servlets/purl/574238-oiySQz/webviewable/574238.pdf
Isaaks, E. H., & Srivastava, R. M. (1989). An introduction to applied geostatistics. Oxford, UK: Oxford
University Press.
Reynolds, W. C., & Perkins, H. C. (1977). Engineering thermodynamics. New York: McGraw-Hill.
Gregory P. Flach, PhD, P.E., is a fellow engineer at the Savannah River National Laboratory (SRNL),
where he has worked the past 17 years on a variety of environmental and nuclear engineering topics. He
currently specializes in mathematical analysis and numerical simulation of porous media transport.
Frank C. Sappington, retired principal engineer at the Savannah River National Laboratory, has 22
years of civil engineering experience. At SRNL, he developed, deployed, and tested new groundwater remedi-
ation technologies, horizontal and vertical barrier systems, and groundwater extraction systems. His BS de-
gree in civil engineering is from the Southern Polytechnic State University.
Kenneth L. Dixon, P.E., is a principal engineer at the Savannah River National Laboratory, where he has
worked the past 14 years on a variety of environmental engineering projects. He specializes in pilot-scale
testing of innovative remedial technologies and numerical simulation of contaminant transport in the va-
dose zone.
9g © 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem
-------
APPENDIX F - RESRAD SUMMARY REPORT
Final 12/23/10
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 1
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Dose Conversion Factor (and Related) Parameter Summary ... 2
Site-Specific Parameter Summary 5
Summary of Pathway Selections 10
Contaminated Zone and Total Dose Summary 11
Total Dose Components
Time = O.OOOE+00 12
Time = 1. OOOE+00 13
Time = 3. OOOE+00 14
Time = 1. OOOE+01 15
Time = 3. OOOE+01 16
Time = 1. OOOE+02 17
Time = 3. OOOE+02 18
Time = 1. OOOE+03 19
Dose/Source Ratios Summed Over All Pathways 20
Single Radionuclide Soil Guidelines 20
Dose Per Nuclide Summed Over All Pathways 21
Soil Concentration Per Nuclide 22
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 2
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
DCF
Ac-
At-
Bi-
Bi-
Bi-
Fr-
Pa-
Pa-
Pa-
Pb-
Pb-
Pb-
Po-
Po-
Po-
Po-
Po-
Ra-
Ra-
Rn-
Rn-
Th-
Th-
Th-
Th-
Tl-
Tl-
U-2
U-2
U-2
Parameter
Current
Value#
Base
Case*
Parameter
Name
's for external ground radiation, (mrem/yr ) / (pCi/g) | |
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
27
18
10
11
14
23
31
34
34m
10
11
14
10
11
14
15
18
23
2 6
19
22
27
30
31
34
07
10
34
35
38
Dose
Ac-
Pa-
Pb-
Ra-
Th-
U-2
2
2
2
2
2
(Source
(Source
(Source
( Source
( Source
( Source
(Source
(Source
(Source
(Source
( Source
( Source
( Source
(Source
(Source
(Source
( Source
( Source
( Source
( Source
(Source
(Source
(Source
( Source
( Source
( Source
( Source
(Source
(Source
(Source
conversion
27 +
31
10 +
26 +
30
D
D
D
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: FGR
: no
: FGR
: FGR
: FGR
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
12)
data)
12)
12)
12)
4 .
5 .
3
2.
9 .
1 .
1 .
1 .
8 .
2 .
3.
1 .
5.
4 .
5 .
1 .
5.
6 .
3.
3.
2 .
5 .
1 .
3.
2.
1 .
0 .
4 .
7 ,
1 .
.951E-04
.847E-03
.606E-03
.559E-01
.808E+00
.980E-01
.906E-01
.155E+01
.967E-02
.447E-03
.064E-01
.341E+00
.231E-05
.764E-02
.138E-04
.016E-03
.642E-05
.034E-01
.176E-02
.083E-01
.354E-03
.212E-01
.209E-03
.643E-02
.410E-02
.980E-02
.OOOE+00
.017E-04
.211E-01
.031E-04
4 .
5 .
3
2.
9 .
1 .
1 .
1 .
8 .
2 .
3.
1 .
5.
4 .
5 .
1 .
5.
6 .
3.
3.
2 .
5 .
1 .
3.
2.
1 .
1-2.
4 .
7 ,
1 .
.951E-04
.847E-03
.606E-03
.559E-01
.808E+00
.980E-01
.906E-01
.155E+01
.967E-02
.447E-03
.064E-01
.341E+00
.231E-05
.764E-02
.138E-04
.016E-03
.642E-05
.034E-01
.176E-02
.083E-01
.354E-03
.212E-01
.209E-03
.643E-02
.410E-02
.980E-02
.OOOE+00
.017E-04
.211E-01
.031E-04
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
DCF1 (
1
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
13)
14)
15)
16)
17)
18)
19)
20)
21)
22)
23)
24)
25)
26)
27)
28)
29)
30)
i
factors for inhalation, mrem/pCi :
34
U-235+D
U-2
U-2
38
38 + D
Dose
Ac-
Pa-
Pb-
Ra-
Th-
U-2
2
2
2
2
2
CO
27 +
31
10 +
26 +
30
nversion
D
D
D
facto
rs for ingestion, mrem/pCi:
34
6 .
1 .
2 .
8 .
3.
1 .
1 .
1 .
1 .
1 .
1 .
7
1 .
5 .
2 .
.724E+00
.280E+00
.320E-02
.594E-03
.260E-01
.320E-01
.230E-01
.180E-01
.180E-01
.480E-02
.060E-02
.276E-03
.321E-03
.480E-04
.830E-04
6 .
1 .
1 .
8 .
3.
1 .
1 .
1 .
1 .
1 .
1 .
5.
1 .
5 .
2 .
.700E+00
.280E+00
.360E-02
.580E-03
.260E-01
.320E-01
.230E-01
.180E-01
.180E-01
.410E-02
.060E-02
.370E-03
.320E-03
.480E-04
.830E-04
DCF2 (
DCF2 (
DCF2 (
DCF2 (
DCF2 (
DCF2 (
DCF2 (
DCF2 (
DCF2 (
DCF3 (
DCF3 (
DCF3 (
DCF3 (
DCF3 (
DCF3 (
1)
2)
3)
4)
5)
6)
7)
8)
9)
1)
2)
3)
4)
5)
6)
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 3
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Current
Value#
Parameter
Name
Food transfer factors:
Ac-227+D , plant/soil concentration ratio, dimensionless
Ac-227+D , beef/livestock-intake ratio, (pCi/kg)/(pCi/d)
Ac-227+D , milk/livestock-intake ratio, (pCi/L)/(pCi/d)
plant/soil concentration ratio, dimensionless
beef/livestock-intake ratio, (pCi/kg)/(pCi/d)
milk/livestock-intake ratio, (pCi/L)/(pCi/d)
plant/soil concentration ratio, dimensionless
beef/livestock-intake ratio, (pCi/kg)/(pCi/d)
milk/livestock-intake ratio, (pCi/L)/(pCi/d)
plant/soil concentration ratio, dimensionless
beef/livestock-intake ratio, (pCi/kg)/(pCi/d)
milk/livestock-intake ratio, (pCi/L)/(pCi/d)
plant/soil concentration ratio, dimensionless
beef/livestock-intake ratio, (pCi/kg)/(pCi/d)
milk/livestock-intake ratio, (pCi/L)/(pCi/d)
plant/soil concentration ratio, dimensionless
beef/livestock-intake ratio, (pCi/kg)/(pCi/d)
milk/livestock-intake ratio, (pCi/L)/(pCi/d)
plant/soil concentration ratio, dimensionless
beef/livestock-intake ratio, (pCi/kg)/(pCi/d)
milk/livestock-intake ratio, (pCi/L)/(pCi/d)
,1)
plant/soil concentration ratio, dimensionless
beef/livestock-intake ratio, (pCi/kg)/(pCi/d)
milk/livestock-intake ratio, (pCi/L)/(pCi/d)
plant/soil concentration ratio, dimensionless
beef/livestock-intake ratio, (pCi/kg)/(pCi/d)
milk/livestock-intake ratio, (pCi/L)/(pCi/d)
RTF(
RTF(
RTF( 9,3)
Bioaccumulation factors, fresh water, L/kg:
Ac-227+D , fish
Ac-227+D , Crustacea and mollusks
BIOFAC( 1,1)
BIOFAC( 1,2)
fish
Crustacea and mollusks
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 4
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Current
Value#
Parameter
Name
BIOFAC(
BIOFAC(
fish
Crustacea and mollusks
fish
Crustacea and mollusks
BIOFAC(
BIOFAC(
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 5
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Parameter
Area of contaminated zone (m**2)
Thickness of contaminated zone (m)
Fraction of contamination that is submerged
Length parallel to aquifer flow (m)
Basic radiation dose limit (mrem/yr)
Time since placement of material (yr)
Times for calculations (yr)
Times for calculations (yr)
Times for calculations (yr)
Times for calculations (yr)
Times for calculations (yr)
Times for calculations (yr)
Times for calculations (yr)
Times for calculations (yr)
Times for calculations (yr)
User
Input
1 .OOOE+04
2.000E+00
O.OOOE+00
l.OOOE+02
2.500E+01
0.OOOE+00
1 . OOOE+00
3.OOOE+00
l.OOOE+01
3.000E+01
l.OOOE+02
3.000E+02
1.OOOE+03
not used
not used
Default
1.OOOE+04
2.OOOE+00
O.OOOE+00
l.OOOE+02
3.000E+01
0.OOOE+00
1.OOOE+00
3.OOOE+00
l.OOOE+01
3.000E+01
l.OOOE+02
3.000E+02
1.OOOE+03
0.OOOE+00
0.OOOE+00
Used by RESRAD
(If different from user input)
Parameter
Name
AREA
THICKO
SUBMFRACT
LCZPAQ
BRDL
TI
2)
3)
Initial principal radionuclide (pCi/g): U-234
Initial principal radionuclide (pCi/g): U-235
Initial principal radionuclide (pCi/g):
Concentration in groundwater (pCi/L):
Concentration in groundwater (pCi/L):
12 | Concentration in groundwater (pCi/L): U-238
1.OOOE+01
Cover depth (m)
Density of cover material (g/cm**3)
Cover depth erosion rate (m/yr)
Density of contaminated zone (g/cm**3)
Contaminated zone erosion rate (m/yr)
Contaminated zone total porosity
Contaminated zone field capacity
Contaminated zone hydraulic conductivity
Contaminated zone b parameter
Average annual wind speed (m/sec)
Humidity in air (g/m**3)
Evapotranspiration coefficient
Precipitation (m/yr)
Irrigation (m/yr)
Irrigation mode
Runoff coefficient
Watershed area for nearby stream or pond
Accuracy for water/soil computations
O.OOOE+00
not used
not used
1.500E+00
1.OOOE-03
3.OOOE-01
2.000E-01
1.OOOE+00
5.300E+00
2.OOOE+00
not used
5 .OOOE-01
2 .540E-01
6.OOOE-01
overhead
2.OOOE-01
1.OOOE+06
1.OOOE-03
O.OOOE+00
1.500E+00
1.OOOE-03
1.500E+00
1.OOOE-03
4.OOOE-01
2.OOOE-01
l.OOOE+01
5.300E+00
2.OOOE+00
8.OOOE+00
5.OOOE-01
1.OOOE+00
2.OOOE-01
overhead
2.OOOE-01
1.OOOE+06
1.OOOE-03
COVERO
DENSCV
VCV
DENSCZ
VCZ
TPCZ
FCCZ
HCCZ
BCZ
WIND
HUMID
EVAPTR
PRECIP
RI
IDITCH
RUNOFF
WAREA
EPS
Density of saturated zone (g/cm**3)
Saturated zone total porosity
Saturated zone effective porosity
Saturated zone field capacity
Saturated zone hydraulic conductivity (m/yr)
Saturated zone hydraulic gradient
Saturated zone b parameter
Water table drop rate (m/yr)
v/WT
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 6
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
R014
R014
R014
Parameter
_1 pump intake depth (m below water table)
iel: Nondis
_1 pumping
iber of uns
sat. zone 1
sat. zone 1
sat. zone 1
sat. zone 1
sat. zone 1
sat. zone 1
sat. zone 1
s tribution
Contaminate
Jnsaturated
Saturated z
jeach rate
Solubil i ty
s tribution
Contaminate
Jnsaturated
Saturated z
jeach rate
Solubil i ty
s tribution
Contaminate
Jnsaturated
Saturated z
jeach rate
Solubil i ty
stribution
Contaminate
Jnsaturated
Saturated z
jeach rate
Solubil i ty
stribution
Contaminate
Jnsaturated
Saturated z
jeach rate
Solubilitv
persion
rate (m*
aturated
, thickn
, soil d
, total
(ND) or Mass-Balance (MB)
*3/yr)
zone strata
ess (m)
ensity (g/cm**3)
oorosity
1
User
Input
OOOE+
Used by RESRAD | Parameter
Default (If different from user input) Name
01
ND
2
1
1
1
1 3
, effective porosity | 2
, field
, soil-s
capacity
pecific b parameter
, hydraulic conductivity (m/yr)
coef f ici
d zone (
zone 1
one (cm*
(/yr)
constant
coef f ici
d zone (
zone 1
one (cm*
(/yr)
constant
coef f ici
d zone (
zone 1
one (cm*
(/yr)
constant
coef f ici
d zone (
zone 1
one (cm*
(/yr)
constant
coef f ici
d zone (
zone 1
one (cm*
(/yr)
constant
ents for U-234
cm**3/g)
(cm**3/g)
*3/g)
ents for U-235
cm**3/g)
(cm**3/g)
*3/g)
ents for U-238
cm**3/g)
(cm**3/g)
*3/g)
ents for daughter Ac-227
cm**3/g)
(cm**3/g)
*3/g)
ents for daughter Pa-231
cm**3/g)
(cm**3/g)
*3/g)
2
5
1
1 5
5
5
0
n
1 5
5
5
0
n
1 5
5
5
0
n
2
2
2
0
n
5
5
5
0
n
500E+
400E+
500E+
OOOE-
OOOE-
OOOE-
300E+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
OOOE+
02
01
00
01
01
01
00
00
01
01
01
00
00
01
01
01
00
00
01
01
01
00
00
01
01
01
00
00
01
01
01
00
00
1
OOOE
+ 01 |
ND |
2
1
4
1
4
2
2
^
1
5
^
^
0
o
5
5
5
0
o
5
5
5
0
o
2
2
2
0
o
5
5
5
0
o
500E
OOOE
500E
OOOE
OOOE
OOOE
300E
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
OOOE
+ 02 |
+ 00
+ 00
-01 |
-01 |
-01 |
+ 00 |
+ 01 |
+ 01 |
+ 01 |
+ 01 |
+00 | 2.667E-03
+00 not used
+ 01 |
+ 01 |
+ 01 |
+00 | 2.667E-03
+00 not used
+ 01 |
+ 01 |
+ 01 |
+00 | 2.667E-03
+00 not used
+ 01 |
+ 01 |
+ 01 |
+00 | 6.631E-03
+00 not used
+ 01 |
+ 01 |
+ 01 |
+00 | 2.667E-03
+00 1 not used
DWIBWT
MODEL
UW
NS
H(l)
DENSUZ (
TPUZ(l)
EPUZ(l)
FCUZ(l)
BUZ(l)
HCUZ(l)
DCNUCC(
DCNUCU(
DCNUCS (
ALEACH (
SOLUBK(
DCNUCC(
DCNUCU(
DCNUCS (
ALEACH (
SOLUBK(
DCNUCC(
DCNUCU(
DCNUCS (
ALEACH (
SOLUBK(
DCNUCC(
DCNUCU(
DCNUCS (
ALEACH (
SOLUBK(
DCNUCC (
DCNUCU(
DCNUCS (
ALEACH (
SOLUBK(
1)
6)
6,
6)
6)
6)
7)
•-J
7)
7)
7)
8)
g
8)
8)
8 )
1)
1,
1)
1)
1)
2)
2,
2)
2)
2)
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 7
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Parameter
User
Input
Default
Used by RESRAD | Parameter
(If different from user input) | Name
Distribution coefficients for daughter Pb-210
Contaminated zone (cm**3/g)
Unsaturated zone 1 (cm**3/g)
Saturated zone (cm**3/g)
Leach rate (/yr)
Solubility constant
l.OOOE+02 | l.OOOE+02
l.OOOE+02 | l.OOOE+02
l.OOOE+02 | l.OOOE+02
O.OOOE+00 | O.OOOE+00
O.OOOE+00 I O.OOOE+00
Distribution coefficients for daughter Ra-226
Contaminated zone (cm**3/g)
Unsaturated zone 1 (cm**3/g)
Saturated zone (cm**3/g)
Leach rate (/yr)
Solubility constant
7.000E+01 | 7.000E+01
7.000E+01 | 7.000E+01
7.000E+01 | 7.000E+01
O.OOOE+00 | O.OOOE+00
O.OOOE+00 I O.OOOE+00
Distribution coefficients for daughter Th-230
Contaminated zone (cm**3/g)
Unsaturated zone 1 (cm**3/g)
Saturated zone (cm**3/g)
Leach rate (/yr)
Solubility constant
6.000E+04 | 6.000E+04
6.000E+04 | 6.000E+04
6.000E+04 | 6.000E+04
O.OOOE+00 | O.OOOE+00
O.OOOE+00 I O.OOOE+00
2.231E-06
not used
Inhalation rate (m**3/yr)
Mass loading for inhalation (g/m**3)
Exposure duration
Shielding factor, inhalation
Shielding factor, external gamma
Fraction of time spent indoors
Fraction of time spent outdoors (on site)
Shape factor flag, external gamma
Radii of shape factor array (used if FS = -1)
Outer annular radius (m), ring 1:
Outer annular radius (m), ring 2:
Outer annular radius (m), ring 3:
Outer annular radius (m), ring 4:
Outer annular radius (m), ring 5:
Outer annular radius (m), ring 6:
Outer annular radius (m), ring 7:
Outer annular radius (m), ring 8:
Outer annular radius (m), ring 9:
Outer annular radius (m), ring 10:
Outer annular radius (m), ring 11:
Outer annular radius (m), ring 12:
8.400E+03
l.OOOE-04
3.000E+01
4.OOOE-01
7.OOOE-01
5.OOOE-01
5.OOOE-01
1.OOOE+00
8.400E+03
l.OOOE-04
3.000E+01
4.OOOE-01
7.OOOE-01
5.OOOE-01
2.500E-01
1.OOOE+00
5.000E+01
7.071E+01
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
O.OOOE+00
>0 shows circular AREA.
INHALR
MLINH
ED
SHF3
SHF1
FIND
FOTD
FS
RAD
RAD
RAD
RAD
RAD
RAD
RAD
RAD
RAD
RAD
RAD
RAD
SHAPE( 1)
SHAPE( 2)
SHAPE( 3)
SHAPE( 4)
SHAPE( 5)
SHAPE( 6)
SHAPE( 7)
SHAPE( 8)
SHAPE( 9)
SHAPE(10)
SHAPE(11)
SHAPE(12)
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 8
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Parameter
Fractions of annular areas within AREA:
Ring 1
Ring 2
Ring 3
Ring 4
Ring 5
Ring 6
Ring 7
Ring 8
Ring 9
Ring 10
Ring 11
Ring 12
Fruits, vegetables and grain consumption (kg/yr)
Leafy vegetable consumption (kg/yr)
Milk consumption (L/yr)
Meat and poultry consumption (kg/yr)
Fish consumption (kg/yr)
Other seafood consumption (kg/yr)
Soil ingestion rate (g/yr)
Drinking water intake (L/yr)
Contamination fraction of drinking water
Contamination fraction of household water
Contamination fraction of livestock water
Contamination fraction of irrigation water
Contamination fraction of aquatic food
Contamination fraction of plant food
Contamination fraction of meat
Contamination fraction of milk
Livestock fodder intake for meat (kg/day)
Livestock fodder intake for milk (kg/day)
Livestock water intake for meat (L/day)
Livestock water intake for milk (L/day)
Livestock soil intake (kg/day)
Mass loading for foliar deposition (g/m**3)
Depth of soil mixing layer (m)
Depth of roots (m)
Drinking water fraction from ground water
Household water fraction from ground water
Livestock water fraction from ground water
Irrigation fraction from ground water
Wet weight crop yield for Non-Leafy (kg/m**2)
Wet weight crop yield for Leafy (kg/m**2)
Wet weight crop yield for Fodder (kg/m**2)
Growing Season for Non-Leafy (years)
Growing Season for Leafy (years)
Growing Season for Fodder (years)
User
Input
not used
not used
not used
not used
not used
not used
not used
not used
not used
not used
not used
not used
1.600E+02
1.400E+01
9.200E+01
6.300E+01
5.400E+00
9.000E-01
3.650E+01
5.100E+02
l.OOOE+00
l.OOOE+00
l.OOOE+00
l.OOOE+00
5.000E-01
-1
-1
1-1
6.800E+01
5.500E+01
5.000E+01
1.600E+02
5.000E-01
l.OOOE-04
1.500E-01
9.000E-01
l.OOOE+00
l.OOOE+00
l.OOOE+00
l.OOOE+00
7.000E-01
1.500E+00
1.100E+00
1.700E-01
2.500E-01
8.000E-02
I Used by RESRAD | Parameter
Default (If different from user input) Name
1.
2.
0.
0.
0 .
0 .
0 .
0.
0.
0.
0.
0 .
1.
1.
9 •
6.
5.
9 •
3.
5.
1.
1.
1.
1.
5.
-1
-1
-1
6.
5.
5.
1.
5.
1.
1.
9
1.
1.
1.
1.
7 .
1.
1.
1.
2.
8.
.OOOE
.732E
.OOOE
.OOOE
.OOOE
.OOOE
.OOOE
.OOOE
.OOOE
.OOOE
.OOOE
.OOOE
.600E
.400E
.200E
.300E
.400E
.OOOE
.650E
.100E
.OOOE
.OOOE
.OOOE
.OOOE
+ 00 |
-01 |
+ 00 |
+ 00 |
+ 00 |
+ 00 |
+ 00 |
+ 00 |
+ 00 |
+ 00 |
+ 00 |
+ 00 |
+ 02 |
+ 01 |
+ 01 |
+ 01 |
+ 00 |
-01 |
+ 01 |
+ 02 |
+ 00 |
+ 00 |
+ 00 |
+ 00 |
.OOOE-01 |
.800E
.500E
.OOOE
.600E
.OOOE
.OOOE
.500E
.OOOE
.OOOE
.OOOE
.OOOE
.OOOE
.OOOE
.500E
.100E
.700E
.500E
.OOOE
0.500E+00
0.500E+00
0.500E+00
+ 01 |
+ 01 |
+ 01 |
+ 02 |
-01 |
-04 |
-01 |
-01 |
+ 00 |
+ 00 |
+ 00 |
+ 00 |
-01 |
+ 00 |
+ 00 |
-01 |
-01 |
-02 |
FRACA (
FRACA (
FRACA (
FRACA (
FRACA (
FRACA (
FRACA (
FRACA (
FRACA (
1)
2)
3)
4)
5)
6)
7)
8)
9)
FRACA (10)
FRACA (11)
FRACA ( 1
DIET(l)
DIET(2)
DIET(3)
DIET(4)
DIET(5)
DIET(6)
SOIL
DWI
FDW
FHHW
FLW
FIRW
FR9
FPLANT
FMEAT
FMILK
LFI5
LFI6
LWI5
LWI6
LSI
MLFD
DM
DROOT
FGWDW
FGWHH
FGWLW
FGWIR
YV(1)
YV(2)
YV(3)
TE(1)
TE(2)
TE(3)
2)
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 9
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Parameter
Transloca tion Factor for Non-Leafy
Translocation Factor for Leafy
Translocation Factor for Fodder
Dry Foliar Interception Fraction for Non-Leafy
Dry Foliar Interception Fraction for Leafy
Dry Foliar Interception Fraction for Fodder
Wet Foliar Interception Fraction for Non-Leafy
Wet Foliar Interception Fraction for Leafy
Wet Foliar Interception Fraction for Fodder
Weathering Removal Constant for Vegetation
C-12 concentration in water (g/cm**3)
C-12 concentration in contaminated soil (g/g)
Fraction of vegetation carbon from soil
Fraction of vegetation carbon from air
C-14 evasion layer thickness in soil (m)
C-14 evasion flux rate from soil (I/sec)
C-12 evasion flux rate from soil (I/sec)
Fraction of grain in beef cattle feed
Fraction of grain in milk cow feed
Storage times of contaminated foodstuffs (days) :
Fruits, non-leafy vegetables, and grain
Leafy vegetables
Milk
Meat and poultry
Fish
Crustacea and mollusks
Well water
Surface water
Livestock fodder
Thickness of building foundation (m)
Bulk density of building foundation (g/cm**3)
Total porosity of the cover material
Total porosity of the building foundation
Volumetric water content of the cover material
Volumetric water content of the foundation
Diffusion coefficient for radon gas (m/sec) :
in cover material
in foundation material
in contaminated zone soil
Radon vertical dimension of mixing (m)
Average building air exchange rate (1/hr)
Height of the building (room) (m)
Building interior area factor
Building depth below ground surface (m)
Emanating power of Rn-222 gas
Emanating power of Rn-220 gas
Number of graphical time points
User
Input
l.OOOE-01
l.OOOE+00
l.OOOE+00
2.500E-01
2.500E-01
2.500E-01
2.500E-01
2.500E-01
2.500E-01
2.000E+01
not used
not used
not used
not used
not used
not used
not used
not used
not used
1.400E+01
l.OOOE+00
l.OOOE+00
2.000E+01
7.000E+00
7.000E+00
l.OOOE+00
l.OOOE+00
4.500E+01
1.500E-01
2.400E+00
not used
l.OOOE-01
not used
3.000E-02
not used
3.000E-07
2.000E-06
2.000E+00
5.000E-01
2.500E+00
O.OOOE+00
-1 .OOOE+00
2.500E-01
not used
32
I Used by RESRAD
Default (If different from user input)
1.
1.
1.
2.
2.
2.
2.
2.
2.
2.
2.
3.
.OOOE-01 |
.OOOE
.OOOE
.500E
.500E
.500E
.500E
.500E
.500E
.OOOE
.OOOE
+ 00 |
+ 00 |
-01 |
-01 |
-01 |
-01 |
-01 |
-01 |
+ 01 |
-05 |
.OOOE-02 |
2.000E-02 |
9 .
3
7 .
1.
8.
2.
1.
1.
1.
2.
7
7
1.
1.
4 .
1.
2.
4 .
1.
5 .
3 •
.800E-01 |
.OOOE
.OOOE
.OOOE
.OOOE
.OOOE
.400E
.OOOE
.OOOE
.OOOE
.OOOE
.OOOE
.OOOE
.OOOE
.500E
.500E
.400E
.OOOE
.OOOE
.OOOE
.OOOE
-01 |
-07 |
-10 |
-01 |
-01 |
+ 01 |
+ 00 |
+ 00 |
+ 01 |
+ 00 |
+ 00 |
+ 00 |
+ 00 |
+ 01 |
-01 |
+ 00 |
-01 |
-01 |
-02 |
-02 |
2.000E-06 |
3.
.OOOE-07 |
2.000E-06 |
2.
5 .
2.
0.
-1.
2.
1.
.OOOE
.OOOE
.500E
.OOOE
.OOOE
.500E
.500E
___
+ 00 |
-01 |
+ 00 |
+00 | code computed (time dependent)
+00 code computed (time dependent)
-01 |
-01 |
—
Parameter
Name
TIV(l)
TIV(2)
TIV(3)
RDRY ( 1 )
RDRY ( 2 )
RDRY ( 3 )
RWET ( 1 )
RWET ( 2 )
RWET ( 3 )
WLAM
C12WTR
C12CZ
CSOIL
CAIR
DMC
EVSN
REVSN
AVFG4
AVFG5
STOR T (
STOR T (
STOR T (
1)
2)
3)
STOR T (4)
STOR T (
STOR T (
STOR T (
5)
6)
7)
STOR T (8)
STOR T (
FLOOR1
DENSFL
TPCV
TPFL
PH20CV
PH20FL
DIFCV
DIFFL
DIFCZ
HMIX
REXG
HRM
FAI
DMFL
9)
EMANA ( 1 )
EMANA ( 2
NPTS
)
-------
RESRAD, Version 6.5 T1^ Limit = 180 days 08/12/2010 13:04 Page 10
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
| User | | Used by RESRAD | Parameter
Parameter | Input | Default | (If different from user input) | Name
TITL | Maximum number of integration points for dose
TITL | Maximum number of integration points for risk
Summary of Pathway Selections
1 -- external gamma
2 -- inhalation (w/o radon)
3 — plant ingestion
4 — meat ingestion
5 — milk ingestion
9 — radon
Find peak pathway doses
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 11
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Area: 10000.00 square meters
Thickness: 2.00 meters
Cover Depth: 0.00 meters
Total Dose TDOSE(t), mrem/yr
Basic Radiation Dose Limit = 2.500E+01 mrem/yr
Total Mixture Sum M(t) = Fraction of Basic Dose Limit Received at Time (t)
t (years): O.OOOE+00 l.OOOE+00 3.000E+00 l.OOOE+01 3.000E+01 l.OOOE+02 3.000E+02 l.OOOE+03
TDOSE(t): 3.353E+00 3.344E+00 3.327E+00 3.266E+00 3.101E+00 2.596E+00 1.627E+00 6.247E-01
M(t): 1.341E-01 1.338E-01 1.331E-01 1.307E-01 1.240E-01 1.038E-01 6.510E-02 2.499E-02
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 12
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Water Independent Pathways (Inhalation excludes radon)
Ground Inhalation Radon Plant Meat Milk Soil
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 3.288E-03 0.0010 1.312E-01 0.0391 4.490E-07 0.0000 6.151E-01 0.1834 2.029E-02 0.0061 4.975E-02 0.0148 1.032E-01 0.0308
U-235 3.062E-01 0.0913 6.115E-03 0.0018 O.OOOE+00 0.0000 2.910E-02 0.0087 9.671E-04 0.0003 2.350E-03 0.0007 4.875E-03 0.0015
U-238 1.215E+00 0.3623 1.173E-01 0.0350 3.181E-13 0.0000 5.840E-01 0.1742 1.927E-02 0.0057 4.724E-02 0.0141 9.795E-02 0.0292
Water Dependent Pathways
Water Fish Radon Plant Meat Milk All Pathways*
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 9.228E-01 0.2752
U-235 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 3.496E-01 0.1043
U-238 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 2.081E+00 0.6205
'Sum of all water independent and dependent pathways.
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 13
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Water Independent Pathways (Inhalation excludes radon)
Ground Inhalation Radon Plant Meat Milk Soil
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 3.280E-03 0.0010 1.309E-01 0.0391 3.139E-06 0.0000 6.134E-01 0.1834 2.024E-02 0.0061 4.962E-02 0.0148 1.029E-01 0.0308
U-235 3.054E-01 0.0913 6.100E-03 0.0018 O.OOOE+00 0.0000 2.912E-02 0.0087 9.851E-04 0.0003 2.344E-03 0.0007 4.866E-03 0.0015
U-238 1.212E+00 0.3623 1.170E-01 0.0350 4.764E-12 0.0000 5.824E-01 0.1742 1.922E-02 0.0057 4.711E-02 0.0141 9.769E-02 0.0292
Water Dependent Pathways
Water Fish Radon Plant Meat Milk All Pathways*
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 9.203E-01 0.2752
U-235 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 3.488E-01 0.1043
U-238 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 2.075E+00 0.6205
*Sum of all water independent and dependent pathways.
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 14
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Water Independent Pathways (Inhalation excludes radon)
Ground Inhalation Radon Plant Meat Milk Soil
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 3.264E-03 0.0010 1.302E-01 0.0391 1.654E-05 0.0000 6.102E-01 0.1834 2.013E-02 0.0061 4.936E-02 0.0148 1.023E-01 0.0308
U-235 3.038E-01 0.0913 6.071E-03 0.0018 O.OOOE+00 0.0000 2.916E-02 0.0088 1.021E-03 0.0003 2.331E-03 0.0007 4.849E-03 0.0015
U-238 1.205E+00 0.3623 1.164E-01 0.0350 5.538E-11 0.0000 5.793E-01 0.1741 1.912E-02 0.0057 4.686E-02 0.0141 9.717E-02 0.0292
Water Dependent Pathways
Water Fish Radon Plant Meat Milk All Pathways*
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 9.155E-01 0.2752
U-235 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 3.472E-01 0.1044
U-238 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 2.064E+00 0.6204
*Sum of all water independent and dependent pathways.
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 15
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Water Independent Pathways (Inhalation excludes radon)
Ground Inhalation Radon Plant Meat Milk Soil
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 3.221E-03 0.0010 1.278E-01 0.0391 1.462E-04 0.0000 5.989E-01 0.1834 1.976E-02 0.0060 4.844E-02 0.0148 1.005E-01 0.0308
U-235 2.982E-01 0.0913 5.978E-03 0.0018 O.OOOE+00 0.0000 2.933E-02 0.0090 1.145E-03 0.0004 2.289E-03 0.0007 4.795E-03 0.0015
U-238 1.183E+00 0.3621 1.143E-01 0.0350 1.449E-09 0.0000 5.686E-01 0.1741 1.876E-02 0.0057 4.600E-02 0.0141 9.537E-02 0.0292
Water Dependent Pathways
Water Fish Radon Plant Meat Milk All Pathways*
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 8.987E-01 0.2752
U-235 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 3.417E-01 0.1046
U-238 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 2.026E+00 0.6202
*Sum of all water independent and dependent pathways.
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 16
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Water Independent Pathways (Inhalation excludes radon)
Ground Inhalation Radon Plant Meat Milk Soil
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 3.192E-03 0.0010 1.212E-01 0.0391 1.192E-03 0.0004 5.679E-01 0.1831 1.874E-02 0.0060 4.593E-02 0.0148 9.527E-02 0.0307
U-235 2.829E-01 0.0912 5.751E-03 0.0019 O.OOOE+00 0.0000 2.990E-02 0.0096 1.471E-03 0.0005 2.171E-03 0.0007 4.669E-03 0.0015
U-238 1.121E+00 0.3616 1.083E-01 0.0349 3.410E-08 0.0000 5.391E-01 0.1739 1.779E-02 0.0057 4.361E-02 0.0141 9.042E-02 0.0292
Water Dependent Pathways
Water Fish Radon Plant Meat Milk All Pathways*
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 8.535E-01 0.2752
U-235 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 3.268E-01 0.1054
U-238 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 1.921E+00 0.6194
*Sum of all water independent and dependent pathways.
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 17
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Water Independent Pathways (Inhalation excludes radon)
Ground Inhalation Radon Plant Meat Milk Soil
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 4.017E-03 0.0015 1.007E-01 0.0388 1.150E-02 0.0044 4.727E-01 0.1821 1.559E-02 0.0060 3.813E-02 0.0147 7.917E-02 0.0305
U-235 2.355E-01 0.0907 5.139E-03 0.0020 O.OOOE+00 0.0000 3.145E-02 0.0121 2.341E-03 0.0009 1.807E-03 0.0007 4.331E-03 0.0017
U-238 9.304E-01 0.3584 8.990E-02 0.0346 1.065E-06 0.0000 4.474E-01 0.1723 1.476E-02 0.0057 3.619E-02 0.0139 7.504E-02 0.0289
Water Dependent Pathways
Water Fish Radon Plant Meat Milk All Pathways*
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 7.218E-01 0.2780
U-235 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 2.806E-01 0.1081
U-238 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 1.594E+00 0.6139
*Sum of all water independent and dependent pathways.
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 18
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Water Independent Pathways (Inhalation excludes radon)
Ground Inhalation Radon Plant Meat Milk Soil
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 1.118E-02 0.0069 5.951E-02 0.0366 7.422E-02 0.0456 2.875E-01 0.1767 9.466E-03 0.0058 2.260E-02 0.0139 4.696E-02 0.0289
U-235 1.396E-01 0.0858 3.696E-03 0.0023 O.OOOE+00 0.0000 2.987E-02 0.0184 3.246E-03 0.0020 1.069E-03 0.0007 3.359E-03 0.0021
U-238 5.457E-01 0.3353 5.277E-02 0.0324 1.947E-05 0.0000 2.626E-01 0.1614 8.665E-03 0.0053 2.124E-02 0.0131 4.404E-02 0.0271
Water Dependent Pathways
Water Fish Radon Plant Meat Milk All Pathways*
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 5.115E-01 0.3143
U-235 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 1.809E-01 0.1111
U-238 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 9.351E-01 0.5746
*Sum of all water independent and dependent pathways.
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 19
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Water Independent Pathways (Inhalation excludes radon)
Ground Inhalation Radon Plant Meat Milk Soil
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 3.979E-02 0.0637 1.011E-02 0.0162 2.859E-01 0.4576 9.068E-02 0.1452 2.934E-03 0.0047 4.612E-03 0.0074 9.078E-03 0.0145
U-235 2.239E-02 0.0358 9.374E-04 0.0015 O.OOOE+00 0.0000 1.075E-02 0.0172 1.505E-03 0.0024 1.705E-04 0.0003 9.585E-04 0.0015
U-238 8.438E-02 0.1351 8.175E-03 0.0131 2.007E-04 0.0003 4.070E-02 0.0652 1.343E-03 0.0021 3.291E-03 0.0053 6.823E-03 0.0109
Water Dependent Pathways
Water Fish Radon Plant Meat Milk All Pathways*
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 4.431E-01 0.7093
U-235 9.244E-10 0.0000 3.066E-11 0.0000 O.OOOE+00 0.0000 2.130E-10 0.0000 4.752E-13 0.0000 7.623E-13 0.0000 3.671E-02 0.0588
U-238 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 1.449E-01 0.2320
*Sum of all water independent and dependent pathways.
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 20
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Parent
(i)
Thread
Fraction
9.228E-02 9.203E-02 9.154E-02 8.985E-02 8.517E-02 7.065E-02 4.142E-02 6.389E-03
4.808E-07 1.402E-06 3.230E-06 9.551E-06 2.697E-05 8.108E-05 1.898E-04 3.183E-04
5.357E-08 3.758E-07 1.983E-06 1.755E-05 1.431E-04 1.381E-03 8.925E-03 3.472E-02
U-235+D l.OOOE+00 6.991E-01 6.972E-01 6.935E-01 6.807E-01 6.453E-01 5.354E-01 3.141E-01 4.854E-02
Pa-231 l.OOOE+00 1.171E-04 3.654E-04 8.609E-04 2.554E-03 7.048E-03 1.927E-02 3.373E-02 1.723E-02
Ac-227+D l.OOOE+00 8.194E-07 5.134E-06 2.507E-05 1.974E-04 1.265E-03 6.421E-03 1.396E-02 7.640E-03
§DSR(j) 6.992E-01 6.976E-01 6.944E-01 6.834E-01 6.536E-01 5.611E-01 3.618E-01 7.342E-02
9.999E-01 2.081E-01 2.075E-01 2.064E-01 2.026E-01 1.921E-01 1.593E-01 9.347E-02 1.445E-02
9.999E-01 1.307E-07 3.913E-07 9.082E-07 2.674E-06 7.365E-06 2.013E-05 3.530E-05 1.815E-05
9.999E-01 4.674E-13 3.138E-12 1.623E-11 1.420E-10 1.151E-09 1.104E-08 7.021E-08 2.717E-07
9.999E-01 3.787E-14 5.696E-13 6.636E-12 1.739E-10 4.093E-09 1.279E-07 2.341E-06 2.437E-05
9.999E-01 2.839E-17 7.539E-16 1.687E-14 1.164E-12 6.914E-11 5.062E-09 1.480E-07 1.979E-06
2.081E-01 2.075E-01 2.064E-01 2.026E-01 1.921E-01 1.594E-01 9.350E-02 1.449E-02
Single Radionuclide Soil Guidelines G(i,t) in pCi/g
Basic Radiation Dose Limit = 2.500E+01 mrem/yr
Summed Dose/Source Ratios DSR(i,t) in (mrem/yr)/(pCi/g)
and Single Radionuclide Soil Guidelines G(i,t) in pCi/g
at tmin = time of minimum single radionuclide soil guideline
and at tmax = time of maximum total dose = O.OOOE+00 years
Nuclide Initial
(i) (pCi/g)
tmin
(years)
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 21
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Nuclide Parent
(j) (i)
U-234 U-234 l.OOOE+00 9.228E-01 9.203E-01 9.154E-01 8.985E-01 8.517E-01 7.065E-01 4.142E-01 6.389E-02
U-234 U-238 9.999E-01 1.307E-06 3.913E-06 9.082E-06 2.674E-05 7.365E-05 2.013E-04 3.530E-04 1.815E-04
U-234 §DOSE(j) 9.228E-01 9.203E-01 9.154E-01 8.985E-01 8.518E-01 7.067E-01 4.145E-01 6.407E-02
Th-230 U-234 l.OOOE+00
Th-230 U-238 9.999E-01
Th-230 §DOSE(j)
4.808E-06 1.402E-05 3.230E-05 9.551E-05 2.697E-04 8.108E-04 1.898E-03 3.183E-03
4.674E-12 3.138E-11 1.623E-10 1.420E-09 1.151E-08 1.104E-07 7.021E-07 2.717E-06
4.808E-06 1.402E-05 3.230E-05 9.552E-05 2.697E-04 8.109E-04 1.899E-03 3.186E-03
Ra-226 U-234 l.OOOE+00
Ra-226 U-238 9.999E-01
Ra-226 §DOSE(j)
5.357E-07 3.758E-06 1.983E-05 1.755E-04 1.431E-03 1.381E-02 8.925E-02 3.472E-01
3.787E-13 5.696E-12 6.636E-11 1.739E-09 4.093E-08 1.279E-06 2.341E-05 2.437E-04
5.357E-07 3.758E-06 1.983E-05 1.755E-04 1.431E-03 1.382E-02 8.927E-02 3.475E-01
Pb-210 U-234 l.OOOE+00
Pb-210 U-238 9.999E-01
Pb-210 SDOSE(j)
4.767E-10 6.171E-09 6.475E-08 1.524E-06 3.073E-05 6.490E-04 6.125E-03 2.877E-02
2.839E-16 7.539E-15 1.687E-13 1.164E-11 6.914E-10 5.062E-08 1.480E-06 1.979E-05
4.767E-10 6.171E-09 6.475E-08 1.524E-06 3.073E-05 6.490E-04 6.127E-03 2.879E-02
U-238 U-238 5.400E-05 4.474E-05 4.462E-05 4.438E-05 4.356E-05 4.130E-05 3.426E-05 2.010E-05 3.106E-06
U-238 U-238 9.999E-01 2.081E+00 2.075E+00 2.064E+00 2.026E+00 1.921E+00 1.593E+00 9.347E-01 1.445E-01
U-238 §DOSE(j) 2.081E+00 2.075E+00 2.064E+00 2.026E+00 1.921E+00 1.593E+00 9.347E-01 1.445E-01
THF(i) is the thread fraction of the parent nuclide.
§ is used to indicate summation; the Greek sigma is not included in this font.
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 22
Summary : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
U-234 U-234 l.OOOE+00 l.OOOE+01 9.973E+00 9.920E+00 9.737E+00 9.230E+00 7.657E+00 4.489E+00 6.924E-01
U-234 U-238 9.999E-01 O.OOOE+00 2.827E-05 8.437E-05 2.760E-04 7.850E-04 2.171E-03 3.819E-03 1.966E-03
U-234 §S(j): l.OOOE+01 9.973E+00 9.920E+00 9.737E+00 9.231E+00 7.659E+00 4.492E+00 6.944E-01
Th-230 U-234 l.OOOE+00
Th-230 U-238 9.999E-01
Th-230 §S (j) :
O.OOOE+00 8.990E-05 2.690E-04 8.882E-04 2.595E-03 7.896E-03 1.855E-02 3.113E-02
O.OOOE+00 1.274E-10 1.142E-09 1.253E-08 1.089E-07 1.070E-06 6.850E-06 2.657E-05
O.OOOE+00 8.990E-05 2.690E-04 8.882E-04 2.595E-03 7.897E-03 1.855E-02 3.116E-02
Ra-226 U-234 l.OOOE+00
Ra-226 U-238 9.999E-01
Ra-226 §S ( j) :
O.OOOE+00 1.947E-08 1.746E-07 1.918E-06 1.669E-05 1.652E-04 1.079E-03 4.417E-03
O.OOOE+00 1.839E-14 4.946E-13 1.807E-11 4.697E-10 1.522E-08 2.827E-07 3.100E-06
O.OOOE+00 1.947E-08 1.746E-07 1.918E-06 1.669E-05 1.652E-04 1.080E-03 4.420E-03
Pb-210 U-234 l.OOOE+00
Pb-210 U-238 9.999E-01
Pb-210 §S ( j) :
O.OOOE+00 2.001E-10 5.305E-09 1.843E-07 4.183E-06 9.204E-05 8.781E-04 4.137E-03
O.OOOE+00 1.420E-16 1.132E-14 1.323E-12 9.215E-11 7.133E-09 2.117E-07 2.844E-06
O.OOOE+00 2.001E-10 5.305E-09 1.843E-07 4.183E-06 9.205E-05 8.783E-04 4.140E-03
U-238 U-238 5.400E-05 5.400E-04 5.386E-04 5.357E-04 5.258E-04 4.985E-04 4.136E-04 2.426E-04 3.750E-05
U-238 U-238 9.999E-01 9.999E+00 9.973E+00 9.920E+00 9.736E+00 9.230E+00 7.658E+00 4.492E+00 6.943E-01
U-238 §S(j): l.OOOE+01 9.973E+00 9.920E+00 9.737E+00 9.231E+00 7.659E+00 4.492E+00 6.944E-01
THF(i) is the thread fraction of the parent nuclide.
§ is used to indicate summation; the Greek sigma is not included in this font.
-------
RESRAD, Version 6.5 T1^ Limit = 180 days 08/12/2010 13:04 Page 6
Intrisk : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Water Dependent Pathways
Water Fish Plant Meat Milk All Pathways**
Nuelide risk fract. risk fract. risk fract. risk fract.
Pb-210 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 1.103E-10 0.0000
Ra-226 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 1.472E-09 0.0000
Th-230 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 7.505E-10 0.0000
U-234 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 8.537E-06 0.1644
U-235 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 6.759E-06 0.1302
U-238 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 3.662E-05 0.7053
Total
Radionuclides
Pathway Rn-222 Po-218 Pb-214 Bi-214 Rn-220 Po-216 Pb-212 B1-2K
Total
Ground Inhalation Radon Plant Meat Milk Soil
Nuclide risk fract. risk fract. risk fract. risk fract. risk fract. risk fract. risk fract.
U-234 6.072E-08 0.0012 7.980E-07 0.0154 6.922E-09 0.0001 5.993E-06 0.1154 1.977E-07 0.0038 4.847E-07 0.0093 1.005E-06 0.0194
U-235 6.332E-06 0.1219 3.594E-08 0.0007 O.OOOE+00 0.0000 3.074E-07 0.0059 1.030E-08 0.0002 2.478E-08 0.0005 5.144E-08 0.0010
U-238 2.625E-05 0.5054 6.783E-07 0.0131 1.459E-13 0.0000 7.568E-06 0.1457 2.497E-07 0.0048 6.122E-07 0.0118 1.269E-06 0.0244
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 13:04 Page 27
Intrisk : Homestake Mining Company - Irrigated Land
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD
Water Dependent Pathways
Water
Nuclide risk fract.
Fish
Plant
Meat
fract.
All Pathways**
1.308E-15 0.0000 5.827E-17 0.0000 4.048E-16 0.0000 9.032E-19 0.0000 1.449E-18 0.0000 2.520E-08 0.0048
O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 7.788E-09 0.0015
O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 4.136E-07 0.0790
O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 1.168E-06 0.2230
Th-230 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 1.780E-08 0.0034
U-234 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 5.928E-07 0.1132
O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 4.693E-07 0.0896
O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 2.543E-06 0.4856
Excess Cancer Risks CNRS9(irn,i,t) and CNRS9W(irn,i,t) for Inhalation of
Radon and its Decay Products at t= l.OOOE+03 years
Total
Total Excess Cancer Risk CNRS(i,p,t)*** for Initially Existent Radionuclides (i) and Pathways (p)
and Fraction of Total Risk at t= l.OOOE+03 years
Ground Inhalation Radon Plant Meat Milk Soil
Nuclide risk fract. risk fract. risk fract. risk fract. risk fract. risk fract. risk fract.
U-234 9.139E-07 0.0882 5.917E-08 0.0057 5.116E-06 0.4940 1.042E-06 0.1006 3.388E-08 0.0033 4.844E-08 0.0047 9.194E-08 0.0089
U-235 4.637E-07 0.0448 3.042E-09 0.0003 O.OOOE+00 0.0000 2.807E-08 0.0027 1.605E-09 0.0002 1.729E-09 0.0002 4.181E-09 0.0004
U-238 1.823E-06 0.1760 4.725E-08 0.0046 3.626E-09 0.0004 5.271E-07 0.0509 1.739E-08 0.0017 4.261E-08 0.0041 8.835E-08 0.0085
-------
3.5
3.0
2.5
DOSE: All Nuclides Summed, All Pathways Summed
10
100
1000
Years
Q U-234 Q U-235 D U-238 A Total
C:\RESRAD_FAMILY\RESRAD\6.5\USERFILES\HMCIRRIGATIONFINALRSEADDENDUM.RAD 08/12/2010 13:04 GRAPHICS.ASC Includes All Pathways
-------
DOSE: All Nuclides Summed, Component Pathways
10
100
1000
Years
^^ External A Plant (Water Independent) X Soil Ingest
\J Inhalation ^ Meat (Water Independent) —|— Drinking Water
—3— Radon (Water Independent) )|( Milk (Water Independent) —^f— Fish
Radon (Water Dependent)
Plant (Water Dependent)
Meat (Water Dependent)
Milk (Water Dependent)
C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD 08/12/2010 13:04 GRAPHICS.ASC
-------
0.30
DOSE: All Nuclides Summed, Radon (Water Independent)
0.25
0.20
0.15
0.10
0.05
0.00 >
10
100
1000
Years
Q U-234 Q U-235 D U-238 A Total
C:\RESRAD_FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD 08/12/2010 13:04 GRAPHICS.ASC Pathways: Radon (Water Independent)
-------
6.00E-05
5.00E-05
4.00E-05
3.00E-05
2.00E-05
1.00E-05
O.OOE+01
EXCESS CANCER RISK: All Nuclides Summed, All Pathways Summed
10
100
Years
\
1000
Q U-234 Q U-235 D U-238 A Total
C:\RESRAD_FAMILY\RESRAD\6.5\USERFILES\HMCIRRIGATIONFINALRSEADDENDUM.RAD 08/12/2010 13:04 GRAPHICS.ASC Includes All Pathways
-------
6.00E-06
5.00E-06
4.00E-06
3.00E-06
2.00E-06
1.00E-06
O.OOE+01 >
1
EXCESS CANCER RISK: All Nuclides Summed, Radon (Water Independent)
10
100
Years
1000
Q U-234 Q U-235 D U-238 A Total
C:\RESRAD_FAMILY\RESRAD\6.5\USERFILES\HMC IRRIGATION FINAL RSE ADDENDUM.RAD 08/12/2010 13:04 GRAPHICS.ASC Pathways: Radon (Water Independent)
-------
RESRAD, Version 6.5 T1^ Limit = 180 days 08/12/2010 14:55 Page 9
Concent : Homestake Mining Company - Irrigated Land - Water Dependent
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC WATER DEPENDENT PATHWAYS FINAL.RAD
Nuclide
Ac-227
Pa-231
Pb-210
Ra-226
Th-230
U-234
U-235
U-238
Contaminat-
ted Zone
pCi/g
4.023E-04
5.023E-04
1.126E-02
1.222E-02
1.140E-01
5.758E-01
2.399E-02
5.758E-01
Surface
Soil*
4
5
1
1
1
5
2
5
pCi/g
.023E-04
.023E-04
.126E-02
.222E-02
.140E-01
.758E-01
.399E-02
.758E-01
Air Par-
ticulate
P
6
8
1
2
1
9
4
9
Ci/m**3
.812E-09
.504E-09
. 907E-07
.069E-07
.929E-06
.749E-06
.062E-07
.749E-06
2,
1.
2 ,
3,
1.
1.
6 ,
1.
Well
Water
pCi/L
.487E-01
.283E-01
.153E-01
.231E-01
.519E-03
.470E+02
.127E+00
.470E+02
Surface
Water
pCi/L
2.487E-03
1.283E-03
2.153E-03
3.231E-03
1.519E-05
1.470E+00
6.127E-02
1.470E+00
Concentrations in the media occurring in pathways that are suppressed are calculated using the current input parameter:
i.e. using parameters appearing in the input screen when the pathways are active.
Drinking
Water
Nonleafy Leafy
Vegetable Vegetable
Fodder
Milk
2.487E-01
1.283E-01
2.153E-01
3.231E-01
1.522E-03
1.470E+02
6.127E+00
1.470E+02
2.587E-01
1.383E-01
3.369E-01
8.278E-01
1.157E-01
1.539E+02
6.412E+00
1.539E+02
1.237E+00
6.427E-01
1.183E+00
2.100E+00
1.220E-01
7.319E+02
3.050E+01
7.319E+02
1.353E+00
7.038E-01
1.288E+00
2.248E+00
1.237E-01
8.024E+02
3.343E+01
8.024E+02
2.288E-03
2.975E-04
3.329E-02
1.815E-01
3.211E-04
4.076E+01
1.698E+00
4.076E+01
3.730E-02
1.283E-02
6.456E-01
1.615E-01
1.521E-03
1.471E+01
6.127E-01
1.471E+01
2.486E+00
1.411E-01
2.157E-01
8.077E-01
7.609E-03
8.823E+01
3.676E+00
8.823E+01
^Concentrations are at consumption time and include radioactive decay and ingrowth during storage time.
For livestock fodder, consumption time is t minus meat or milk storage time.
Concentrations in the media occurring in pathways that are suppressed are calculated using the current input parameter:
i.e. using parameters appearing in the input screen when the pathways are active.
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 14:55 Page 19
Summary : Homestake Mining Company - Irrigated Land - Water Dependent
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC WATER DEPENDENT PATHWAYS FINAL.RAD
Water Independent Pathways (Inhalation excludes radon)
Ground Inhalation Radon Plant Meat Milk Soil
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 7.737E-02 0.0059 7.239E-03 0.0005 6.443E-01 0.0489 1.684E-01 0.0128 5.379E-03 0.0004 6.062E-03 0.0005 8.831E-03 0.0007
U-235 1.088E-02 0.0008 4.023E-04 0.0000 O.OOOE+00 0.0000 7.317E-03 0.0006 1.039E-03 0.0001 1.174E-04 0.0000 4.834E-04 0.0000
U-238 4.937E-02 0.0037 4.355E-03 0.0003 3.444E-04 0.0000 3.377E-02 0.0026 1.114E-03 0.0001 2.727E-03 0.0002 4.241E-03 0.0003
Water Dependent Pathways
Water Fish Radon Plant Meat Milk All Pathways*
Nuclide mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract. mrem/yr fract.
U-234 O.OOOE+00 0.0000 O.OOOE+00 0.0000 4.302E-02 0.0033 5.108E+00 0.3877 2.087E-01 0.0158 5.439E-01 0.0413 6.821E+00 0.5177
U-235 O.OOOE+00 0.0000 O.OOOE+00 0.0000 O.OOOE+00 0.0000 7.846E-01 0.0595 9.841E-02 0.0075 2.242E-02 0.0017 9.256E-01 0.0703
U-238 O.OOOE+00 0.0000 O.OOOE+00 0.0000 4.827E-05 0.0000 4.653E+00 0.3532 1.780E-01 0.0135 5.014E-01 0.0381 5.429E+00 0.4120
'Sum of all water independent and dependent pathways.
-------
RESRAD, Version 6.5 T^ Limit = 180 days 08/12/2010 14:55 Page 27
Intrisk : Homestake Mining Company - Irrigated Land - Water Dependent
File : C:\RESRAD FAMILY\RESRAD\6.5\USERFILES\HMC WATER DEPENDENT PATHWAYS FINAL.RAD
Water Dependent Pathways
Water Fish Plant Meat Milk All Pathways**
Nuclide risk fract. risk fract. risk fract. risk fract.
0.0007
E+00 0.0000 O.OOOE+00 0.0000 2.700E-06 0.0204 2.430E-07 0.0018 1.453E-07 0.0011 4.195E-06 0.0317
E+00 0.0000 O.OOOE+00 0.0000 6.093E-07 0.0046 6.789E-08 0.0005 1.084E-07 0.0008 3.257E-06 0.0246
Th-230 O.OOOE+00 0.0000 O.OOOE+00 0.0000 6.599E-10 0.0000 8.973E-12 0.0000 7.693E-13 0.0000 5.710E-08 0.0004
U-234 O.OOOE+00 0.0000 O.OOOE+00 0.0000 4.607E-05 0.3485 1.762E-06 0.0133 4.963E-06 0.0375 5.324E-05 0.4027
O.OOOE+00 0.0000 O.OOOE+00 0.0000 1.962E-06 0.0148 7.506E-08 0.0006 2.114E-07 0.0016 2.476E-06 0.0187
O.OOOE+00 0.0000 O.OOOE+00 0.0000 5.818E-05 0.4401 2.225E-06 0.0168 6.268E-06 0.0474 6.826E-05 0.5164
Total O.OOOE+00 0.0000 O.OOOE+00 0.0000 1.102E-04 0.8333
Radionuclides
Pathway Rn-222 Po-218 Pb-214 Bi-214 Rn-220 Po-216 Pb-212 B1-2K
Total
Ground Inhalation Radon Plant Meat Milk Soil
Nuclide risk fract. risk fract. risk fract. risk fract. risk fract. risk fract. risk fract.
U-234 1.767E-06 0.0122 3.738E-08 0.0003 1.146E-05 0.0793 2.049E-06 0.0142 6.612E-08 0.0005 6.766E-08 0.0005 9.033E-08 0.0006
U-235 2.189E-07 0.0015 1.300E-09 0.0000 O.OOOE+00 0.0000 1.872E-08 0.0001 1.077E-09 0.0000 1.160E-09 0.0000 2.089E-09 0.0000
U-238 1.037E-06 0.0072 2.447E-08 0.0002 6.158E-09 0.0000 4.252E-07 0.0029 1.403E-08 0.0001 3.434E-08 0.0002 5.339E-08 0.0004
-------
APPENDIX G - RESPONSIVENESS SUMMARY
Final 12/23/10
-------
Comment Responses, Draft RSE Addendum, Homestake Superfund Site, Milan, NM
Comment
Number
Commenting
Organization
Report
Section
Report
Page
Comment
Action
Response
Recommendation No. 1 - The flushing of the tailings pile
should be curtailed.
HMC disagrees with this recommendation, and it should be
removed from the final RSE report.
HMC
9.2
45
Non-concur
As stated in the RSE Addendum Report, though progress has
been made in reducing concentrations in the monitoring
points, there are questions about the representativeness of
the samples in these wells due to the very long screened
intervals, the volume of injected water relative to the volume
present, and the lack of response in concentration in
recovered water. Regarding the latter point, though the HMC
comment suggests that a downward trend is present in toe
drain concentrations, but if the data since 2002 is used, the
downward trend is not apparent.
HMC
9.2
45
Recommendation No. 2 - Simplification of the extraction and
injection system is necessary to better focus on capture of
the flux from under the piles and to significantly reduce
dilution as a component of the remedy.
HMC believes this recommendation has some merit and
plans to re-evaluate the existing system to possibly achieve
more efficient mass removal of the constituents.
We are glad to hear a re-evaluation will be conducted.
Noted
HMC
9.2
45
Recommendation No. 3 - Further evaluate capture of
contaminants west of the northwestern corner of the large
tailings pile.
HMC plans to assess the available injection/collection data,
water levels, and chemical data in these areas and re-
evaluate the effectiveness of capture system. Adjustments to
the existing injection/collection system may be considered to
achieve more effective capture.
Noted
-------
HMC
9.2
46
Recommendation No. 4 - If not previously assessed, consider
investigating the potential for contaminant mass loading on
the ground water in the vicinity of the former mill site.
HMC is uncertain of the basis for this recommendation
because demolition of the mill and cover of former mill area
is well-documented. HMC does not believe that additional
investigations of the mill area are necessary and the ACOE's
recommendation should be removed from the final RSE
report.
Non-concur
The RSE Addendum does not associate the elevated ground
water uranium concentrations with the mill debris or other
aspect of the former mill site. The ground water
concentrations are noted as being higher in this area than in
surrounding areas. This is circumstantial evidence of a
source in this area, and we are simply suggesting this may be
worth investigating to help achieve site goals.
HMC
9.2
46
Recommendation No. 5 - Further investigate the extent of
contaminants, particularly uranium in the upper middle
Chinle aquifers and resolve questions regarding dramatically
different water levels among wells in the middle Chinle.
It is unclear why the ACOE recommends further investigation
of the Upper Chinle aquifer when it interprets the
performance of remediation in the Upper Chinle aquifer to
be adequate. HMC believes that the existing monitoring of
the Upper and Middle Chinle aquifers is adequate from a site-
wide perspective and for areas where constituent
concentrations are greater than site standards.
Non-concur,
in part
Based on the mapped extent of uranium in the Upper Chinle
shown in the 2008 Annual Report, Figure 5.3-11, the 0.1
mg/L uranium is not constrained north of CE9 in section 35
or the southern part of section 26. There are no wells in the
Middle Chinle north of the uranium plume shown in figure
6.3-11 of the 2008 Annual Report. Flow according to the
arrows on the figure is to the north, though flow would be
distorted by the injection into CW14. The RSE correctly
identifies the disparate water levels (differing by over 100
feet in some cases) between nearby wells in the Middle
Chinle, sometimes reflecting a gradient opposite that
indicated by the arrows on the figures.
HMC
9.2
46
Recommendation No. 6 - Consider geophysical techniques,
such as electrical resistivity tomography to assess leakage
under the evaporation ponds.
Fluid migrating out of the ponds would have very high total
dissolved solids and are, therefore, highly conductive.
However, the geophysical survey would not be able to
provide any information on leakage rates and would
therefore not provide useful information.
Non-concur
The identification of the migration of highly conductive fluids
in the subsurface would at least be qualitative evidence of
leakage. Repeated measurements showing temporal
changes in the extent of such conductivity anomalies would
allow estimation of volumes through modeling.
-------
HMC
9.2
46
Recommendation No. 7 - Assure decommissioning of any
potentially compromised wells screened in the San Andres
Formation is completed as soon as possible
HMC plans to review available borehole logs for San Andres
Aquifer monitoring wells and identify those which have
screens or gravel packs that extend up into the overlying
Chinle Formation that could potentially allow from possible
cross-contamination. Available water levels will also be
reviewed to determine if a particular well's water level is
consistent with other San Andres Aquifer wells.
Noted
HMC
9.2
46
Recommendation No. 8 - Consider construction of a slurry
wall or PRB around the site to control contaminant migration
from the tailings piles. The decision for implementing such
an alternative would depend on the economics of the
situation.
HMC has evaluated the economics and implementability of a
slurry wall and PRB and found them to be impractical and
cost-prohibitive remedial options given the difficulty of
construction and likelihood of incomplete isolation or
collection of the alluvial groundwater because of the
excessive depth of excavations. The ACOE's recommendation
for further evaluation of slurry walls and PRBs should be
removed from the final RSE report.
The recommendation will not be removed, but the results of
HMC's economic analysis will be noted though no details are
provided as to the assumptions and extent of the economic
impacts analyzed (such as impacts on the treatment plant
operational costs). The slurry wall was intended to be a
suggestion to improve both likelihood of containment and a
way to reduce costs for operations of the treatment plant.
Concur, in
part
HMC
9.2
46
Recommendation No. 9 - Relocation of the tailings should
not be considered further given the risks to the community
and workers and the greenhouse gas emissions that would
be generated during such work.
HMC agrees that relocation of the tailings should not be
considered further. HMC also believes
that it is important to re-emphasize that this "Alternative
Strategy" would create a significant risk
to human health.
Noted
-------
10
HMC
9.2
46
Recommendation No. 10 - If geotechnical considerations
allow, consider expansion of the evaporation pond on the
small tailings pile as means to enhance evaporative capacity.
This has also been recognized by the State of New Mexico,
with the recent approval of DP-725 for the construction of EP
3. In light of this, the recommendation to expand the
evaporation pond on the small tailings is not appropriate. In
addition, expansion would be difficult due to geotechnical
considerations. The expanded pond would need to be tied
into EP-1; this would pose a geotechnical challenge and
would possibly compromise the liner system of EP-1.
The RSE will be amended to remove this recommendation.
Concur
11
HMC
9.2
46
Recommendation No. 11 - Consider either the pretreatment
of high concentration wastes in the collection ponds as is
currently being pilot tested, or adding RO capacity to
increase treatment plant throughput and reduce discharge
to the ponds. The RO treatment plant will be able to operate
at its full potential, with the recent approval of DP-725, and
additional RO capacity is therefore not needed in order to
increase plant throughput.
It is still advisable to increase treatment plant throughput to
minimize loading to the ponds
Non-concur
12
HMC
9.2
46
Recommendation No. 12 - Develop a comprehensive,
regular, and objectives-based monitoring program.
Quantitative long-term monitoring optimization techniques
are highly recommended. HMC plans to evaluate the site
groundwater monitoring program, which includes identifying
and categorizing wells and their intended purpose, followed
by evaluating each monitoring well and determining its
inclusion or exclusion in the monitoring program.
HMC plans to perform this procedure for those monitoring
wells that are required under state permits or federal
license.
Great. We can provide additional guidance on approaches if
desired.
Noted
-------
13
HMC
9.2
47
Recommendation No. 13 - Adjust Air Monitoring Program to
perform sampling of radon decay products to confirm
equilibrium assumption, consider use of multiple radon
background locations to better represent the distribution of
potential concentrations and assess the radon gas potentially
released from the evaporation ponds, especially during
active spraying.
HMC does not believe that any adjustment to the air
monitoring program is required with respect to the radon
decay products as well as the evaporation ponds. HMC is
evaluating the location of the radon background monitor,
and will work with NRC on this evaluation.
Concur that HMC should continue to work with NRC to
evaluate the radon background location as described in the
July-December 2009 Semi-Annual Environmental Monitoring
Report. All other recommendations to confirm important air
monitoring assumptions and improve sampling data
presentation will remain in the report as modified in
response to other stakeholder comments.
Non-concur,
in part
14
HMC
9.2
47
Recommendation No. 14 - Though risks appear minimal with
the current irrigation practice, consider treatment of
contaminated irrigation water via ion exchange prior to
application as a means to remove contaminant mass from
the environment.
HMC requests that Table 5 and Table 6 be removed from
Section 8.1.1 of the report because they were generated
based on the irrelevant and misleading irrigation scenario as
described above. HMC does
not believe this would improve the current irrigation system,
and would be technically infeasible to implement.
Non-concur
The intent of the analysis of treatment options for the
irrigation water was to assess what would be required in
order to address stakeholder concerns and EPA's preference
for treatment. As noted elsewhere, additional treatment
would be required beyond ion exchange for uranium, if the
form of U in the ground water is non-ionic due to complexing
with calcium carbonate. Initial ion exchange to reduce
calcium concentrations would likely yield an anionic form of
the uranium. This additional step would require
regeneration of the resins and the resulting brines would
need to be transported and disposed in the evaporation
ponds. This may or may not be practical, and further
analysis and testing would be required to verify the true
treatment requirements, brine production, and cost.
-------
15
16
17
18
HMC
HMC
HMC
HMC
EXSUM
EXSUM
1.1
1.4
ii
ii
1
3
A conclusion is made that there may have been widespread
impacts on the general water quality (e.g., ions such as
sulfate) of the alluvial aquifer since mill operations began,
but the limited amount of historical data precludes certainty
in this conclusion. HMC believes that this conclusion is
speculation, and the Grants site does not contribute to
widespread impacts. The ACOE fails to recognize that there
are several alluvial systems in the Grants vicinity. The San
Mateo alluvial system underlies the site with contributing
water-quality effects from the Rio San Jose alluvium to the
west and the Lobo alluvium to the east. It is, therefore, the
combination of water quality from each of these alluvial
systems that may represent any potential widespread
impact, and the Rio San Jose alluvium is known to have
elevated sulfate.
A conclusion is made that the seepage modeling likely
overestimates the efficiency of flushing of the tailings. HMC
disagrees with this conclusion. Our review of the model
predictions shows that the model reasonably matches
observed conditions with a lag effect. This lag effect is due to
reductions in extraction within the large tailings pile in recent
years that was not envisioned nor included in the modeling
effort.
A statement is made that leaching from the mill site has
contaminated groundwater. HMC is unaware of any
supporting documentation that the mill site has
contaminated groundwater.
The previous RSE report is mentioned. HMC would like to
point out that this previous report was flawed and had errors
in its interpretations.
Concur, in
part
Non-concur
Non-concur
Non-concur
We are well aware of the complexities of the alluvial systems
at the site. The text makes a statement of fact regarding the
increases in sulfate concentrations. Note that the sulfate
impacts do seem to emanate from the San Mateo drainage,
based on maps of sulfate concentrations in the HMC 2008
Annual Report.
The seepage modeling matches concentrations that have
been impacted by preferential flow through wells and higher
permeability materials.
See response to HMC comment 4 above.
This RSE is not intended to render a judgment on the
previous work. The statements in this section are factual and
non-judgmental.
-------
19
HMC
1.4.3
A statement is made that "Data for samples collected in the
1950s from a couple of alluvial aquifer wells approximate 2.5
miles west of the site (well numbers 0935 and 0936) suggest
significant increases in sulfate concentrations have
occurred." These wells are in the Rio San Jose alluvium west
of and unimpacted by the site. The inference in this section,
however, is that the increasing sulfate in the wells may be
due to the Grants site and it is not. Any observed increase in
sulfate would be due to activities further west and
upgradient of the wells.
Concur
See response to comment 15 above.
20
HMC
1.4.4
The extraction and injection system is stated to be not well
documented. HMC disagrees with this statement. The system
is sufficiently described in the annual groundwater
monitoring report, which contains the volumes of water
removed and injected, constituent concentrations of these
waters, and maps showing the locations of system
components.
Non-concur
The annual reports do provide a wealth of information about
this complex site; however, the operational parameters
(flow, pumping levels) for specific wells are not documented.
It was not easy to assess the performance of the system
because the system seemed to be constantly changing.
21
HMC
1.4.5
The RO treatment capacity is stated as 600 gpm and practical
limitations are less than that. This is incorrect. The RO plant
can be run at higher rates and, with the additional capacity
provided by the third evaporation pond, can be operated at
the 600 gpm rate or higher. The limitation is not in the
clarifier section.
Non-concur
The USACE recorded in their notes at the site visit that there
was a 600 gpm limitation on the clarifier. The USACE
recorded this information from their site visit. If this is in
error, the USACE will replace with what HMC believes to be
the limiting RO plant treatment flow rate. The text will be
changed to indicate that a > 600 gpm flow rate through the
current treatment plant is possible but that alternatives
were developed using a 600 gpm (with allowance for
change out of RO columns).
22
HMC
1.4.6
A discussion of the evaporation ponds is presented, but is
not complete. The ACOE does not mention that pond #2 has
a double liner and pond #1 has a single liner. A third
evaporation pond that has been approved by the NRC has
just received approval from NMED.
This information will be added.
Concur
-------
23
HMC
2.1.1
A statement is made that it is possible the uranium is not as
accessible for dissolution, but it may slowly mobilize over
time. The ACOE provided no basis for this statement, and our
evaluations do not support it either (See HMC's response to
Recommendation No. 1). This statement should be removed
from the final RSE report.
Non-concur
The section actually notes the relative immobility of the
uranium; however, the pH/Eh conditions in the pile are such
that there is a potential for slight on-going mobilization of
the U. This is based on Eh/pH diagrams for U with O, H2O,
andCO2.G17
The ponds are stated as being a possible secondary source of
contaminants affecting air, soil, and groundwater if the liners
under the ponds were to leak. This statement is speculative
and should be removed from the final RSE report.
24
HMC
2.1.3
Non-concur,
in part
We agree that the statement is speculative, but it is true that
if the ponds were to leak, they would be sources. We will
clarify that there is no current evidence of leakage. HMC
must acknowledge, though, that as engineered structures,
these pond liners can fail. It is widely accepted that caps and
liners have some very small but finite permeability due to
imperfections in seams, tears, etc. There is no such thing as
a perfect liner. We note that there have been instances
where the exposed liners have had damage along the berms.
25
HMC
2.1.4
Irrigation with site water is stated as possibly affecting
groundwater through leaching. This is contrary to the ACOE's
finding in the draft RSE report that irrigation has not
impacted groundwater. This statement should be removed
from the final RSE report.
Concur, in
part
We will clarify that there is no evidence for such impacts at
this time and that the severity of the actual future impact is
uncertain
-------
26
HMC
2.2.1
It is stated that the air monitoring program at the Grants site
attempts to quantify the radon in air pathway. HMC has
actually gone to great lengths to "quantify" this pathway and
has found that the measured radon at the site boundary
primarily is from natural background sources, with only a
small component originating from the site. In fact, the EPA
issued a "no action" on Radon in the Record of Decision for
Grants at a point in time when the tailings piles were open
and the mill was still operating. This decision was based on a
comprehensive study where radon concentrations were
measured in nearby homes by an independent competent
scientist. The tailings piles are now covered and the mill has
been decommissioned so the on-site source has been greatly
reduced.
Non-concur
EPA and NMED have identified significant stakeholder
concerns with the current air monitoring program and
requested that the RSE Addendum include an evaluation and
recommendations. The Selected Remedial Approach in the
1989 Record of Decision included the following statement:
"While EPA believes that continued subdivisions monitoring
is unwarranted at this time, EPA recognizes the need to
monitor outdoor radon and windblown particulate levels
south of the disposal area to assure that conditions in the
subdivisions do not significantly change prior to final site
closure. In this regard, EPA will continue to review outdoor
radon monitoring and particulates data collected at the
facility boundary pursuant to NRC-license requirements.
Should an increasing trend in either radon or particulates
levels be noted, EPA and NRC will require monitoring or
corrective action In the subdivisions, whichever Is
appropriate."
27
HMC
2.3
The text incorrectly refers to Figure 1 as the conceptual site
model. The conceptual site is shown on Figure 2. HMC
believes that the conceptual site model is flawed. As
discussed in our response for Recommendation No. 4, HMC
does not believe that the former mill area is a "Primary
Source," as depicted on the conceptual site model.
Additionally, several of the exposure pathways that are
indicated as complete are actually not complete. An example
of this is the incomplete groundwater drinking pathway for a
trespasser, resident, or worker, currently and in the future.
We suggest that the ACOE reexamine this conceptual site
model before issuing the final RSE report.
Non-Concur,
in part
The reference to the CSM Figure will be corrected. The CSM
sources and pathways will be reevaluated based on this and
other stakeholder comments and the information compiled
by HMC in the annual Land Use Review/Survey. The
descriptions and figure will be clarified to better indicate
known sources, receptors and transfer pathways and
potential sources, receptors, and transfer pathways.
-------
28
HMC
3.2
13
The ACOE cites well 0882, located south of the wells used for
irrigation in the northern plume, as providing evidence for
incomplete capture because uranium concentrations have
increased. However, the increase is only on the order of 0.02
mg/L and within typical variability of uranium concentrations
in the alluvial aquifer in this area. The uranium concentration
is below the site standard and below the maximum
contaminant level, and the slight increase is not an indicator
of incomplete capture.
The concentrations measured in well 882 have a systematic
rise in concentration over 13 years and has tripled in
concentration. The data do not suggest the increase is
related to analytical "variability"
Non-concur
29
HMC
3.2
15
Well DD is discussed and the uranium concentration in the
well is speculated to be a result of migration from the tailings
pile. Well DD is an approved background well and the 95
percent confidence limit of uranium concentrations in the
well were used to set the site standard for the alluvial
aquifer. It is highly unlikely that groundwater is flowing to
the north because the water level in well DD is several feet
higher than at the tailings pile. Furthermore, the uranium
concentration has consistently been near the 0.16 mg/L site
standard level since 1995, indicating a steady source of
uranium from upgradient areas, whereas the uranium
concentration at the tailings pile has been decreasing over
this period. If the tailings pile was the source of uranium in
well DD, one would expect the uranium concentration to
decrease to some degree because of the decreasing
concentrations at the tailings pile, but this has not occurred.
The report text essentially agrees with the HMC comment.
We do not attribute the concentrations in well DD to leakage
from the tailings. No changes are required to the report.
Concur
-------
30
HMC
3.4
15
It is stated that the model likely over-predicts the
performance of tailings flushing. A similar statement is made
in the Executive Summary. HMC's review of the model
predictions shows that the model reasonably matches
observed conditions; however, there is a lag effect. This lag
effect is due to reductions in extraction within the large
tailings pile in recent years that was not envisioned nor
included in the modeling effort.
Non-concur
See response to comment 16
31
HMC
3.6
16
It is stated that the flow direction in the San Andres aquifer is
to the northeast. However, the flow direction is toward the
east and lightly southeast, as shown on Figure 8.0-1 of the
2008 Annual Monitoring Report (HMC and Hydro-
Engineering, LLC. 2009).
Concur, in
part
The northeasterly flow was based on water levels in March
2009, as provided in the data base. The text will be revised
to note the easterly to southeasterly flow in 2008.
32
HMC
17
The ACOE states that "According to Homestake, flushing of
the tailings pile will be completed by 2012, with the
remaining groundwater contamination completed by 2017."
The last part of the sentence is worded in an awkward
manner; it should read "...with remediation of the remaining
groundwater contamination completed by 2017."
Change will be made to read as suggested.
Concur, in
part
33
HMC
17
The ACOEs states that "...potentially applicable replacement
technologies are discussed...." Two of the possible strategies,
slurry wall and PRBs are discussed. Each of these
technologies is technically impracticable (see HMC's
response to Recommendation No. 8). The ACOE actually
provides no replacement technologies that have not already
been considered.
Non-concur
Though challenging, based on discussions with vendors it
appears these alternatives are technically feasible. The
report acknowledges there are questions about the
economic advantages to implementation of these
approaches compared to current approaches, particularly
since a portion of the site would be underlain by permeable
bedrock units.
-------
34
HMC
4&
Fig. 14
17
The flushing of the large tailings pile is discussed and Figure
14 is used to show the 2008 uranium concentrations in the
tailings. Although the ACOE uses this figure to show the
variability of uranium in the pile and illustrate their belief
that the flushing has not been effective, HMC believes that
the flushing has been effective at removing uranium mass.
This is demonstrated by comparing the 2000 and 2009 maps
for uranium in the tailings pile, which shows that a significant
amount of uranium has been removed. See also HMC's
response to Recommendation No. 2 for additional evidence
of the effectiveness of the flushing and extraction program.
Below is the 2000 uranium concentration map for the tailings
pile showing uranium concentrations exceeding 30 mg/L in
much of the pile. Also below is a map of the 2009 uranium
concentrations in the pile, which illustrates the significant
reduction in concentrations resulting from the flushing and
extraction program. For 2009, approximately 67.5 percent of
the west side slime area has uranium concentrations less
than 5.0 mg/L, and 45.5 percent of the same area has
concentrations lower than 2.0 mg/L.
Non-concur
The flushing program has made some progress, as the report
acknowledges. As discussed above and in the report, the
concern is that the long screens of the monitoring points
makes it likely that injected water has impacted the
monitoring point, but that the ambient concentrations may
much different. The map was meant to illustrate the wide
variations in concentrations at closely spaced points such
that the flushing is clearly not uniform.
-------
35
HMC
4.1
19
The ACOE presents a calculation of the volume of water
within the tailings and bases the volume on a total porosity
of 30 percent, which is not substantiated or appropriate. The
mobile porosity (i.e., effective porosity) of the tailings should
have been used. The slimes may have a total porosity of
around 30 percent, but the effective porosity is more on the
order of 8 percent and 14 percent for the tailing sands. The
result of this is that the ACOE has most likely overestimated
the volume of water in the tailings, which correspondingly
underestimates the success of the flushing and extraction
system. HMC estimates that approximately one pore volume
has been flushed from the tailings.
Non-concur
The total porosity is of interest. Though it is agreed that the
effective porosity is applicable for assessing the flushing of
the actual pathways, the real goal here is to remove uranium-
rich pore fluid. Note that the "immobile" pore space
contains contaminants that will diffuse back into the mobile
porosity over time and will likely cause rebound in
concentrations. In addition, HMC does not account for the
leakage of injected fluids via the long open intervals in the
wells.
36
HMC
4.1
19
A calculation is made of the natural groundwater flow in the
alluvial aquifer beneath the large tailings pile, which is
substantially overestimated. Based on site data, the
hydraulic conductivity of the alluvium used in the calculation
should be about 20 feet/day, not 80 feet/day. The gradient
of 0.008 is high and should be lower near approximately
0.003. HMC's estimate of the natural flow in the alluvial
aquifer is in the range of 60 to 80 gpm, not 450 gpm as
estimated by the ACOE. Consequently, the amount of alluvial
groundwater that needs to be captured beneath or
surrounding the large tailings pile is considerably less than
what is estimated by the ACOE.
Non-concur
The hydraulic conductivity used in the analysis was within
the range of values (10-800 ft/day) given in the report on site
modeling, though conservatively higher than the "typically
30-60 ft/day" cited in Table 1-1 of that report. The gradient
was estimated from site water levels west of the treatment
plant, and, again is estimated conservatively high. The intent
of the calculation was to estimate a conservatively large
value for the flux for assessing the treatment needs. If the
flux is truly only 60-80 gpm, then the flushing and reinjection
is requiring the plant to treat as much as 3-5 times more
water than necessary.G103
-------
37
HMC
4.2
19-20
The ACOE states that injection of relatively clean water from
other aquifers into the alluvial aquifer may do more to dilute
the plume than treat it. However, injection of water has
demonstrated to be an effective technology for plume
control, and in addition to controlling the plumes, injection is
often necessary to sustain a sufficient saturated thickness in
the alluvial aquifer to enable extraction to occur; otherwise
the aquifer would be dry. An example of this is at Felice
Acres, where injection into the alluvial aquifer occurs. Initial
extraction wells in this area yielded very little water and
wells commonly became dry when pumped. With injection, a
sufficient saturated thickness is maintained that enables
uranium and other constituents to be collected. Without
injection little or no constituent mass would be extracted.
Non-concur
We agree the injected water increases saturated thicknesses
and improves performance of the extraction wells. However,
the injection of significant amounts of clean water clearly has
an impact on concentrations. It is not readily apparent that
there is a water balance between injection, natural flux, and
pumping in all areas, especially in the western portions of
the plumes. The recirculation of injected water into the
extraction system also increases volumes of water needing
treatment, raising costs for operations.
-------
38
HMC
4.2
19-20
The ACOE also states that extraction from the Upper Chinle
draws water downward from the more contaminated alluvial
aquifer. The only area where this could possibly occur is in
the collection pond area where there is an approximate 500-
foot wide zone of saturated alluvium overlying the Upper
Chinle Aquifer, and extraction in the Upper Chinle Aquifer
occurs in this area. However, HMC does not believe that
pumping from the Upper Chinle Aquifer in this limited area is
drawing contaminants downward as the following explains.
The two most important parameters that control the
movement from one aquifer to another are the head in the
driving aquifer and the vertical hydraulic conductivity of the
materials that the water has to move through between the
two aquifers. In the collection pond area, the head in the
alluvial aquifer would have to be substantially higher than
the head in the Upper Chinle Aquifer and the materials
would have to be highly permeable. Review of the 2008
water levels in the two aquifers in this area reveals that there
is minimal head difference...
Non-concur
Based on comparison of water levels in October, 2008 in
alluvial wells near the area of pumping in the Upper Chinle
(south of the Collection Ponds), there is a downward
gradient. Water levels in the alluvial aquifer are between
6530 and 6535 ft msl and water levels in the Upper Chinle, as
shown on Figure 5.2-1 of the 2008 Annual Report are below
6530.
39
HMC
4.4.3
27
The ACOE suggests that a relatively new immobilization
technology, still in lab development, be examined. The
reference given is to "Frysell et al., 2005." This citation is
incorrect; it should be Fryxell et al., 2005 (as noted correctly
in Section 10, References). The referenced work involves the
use of self-assembled monolayers on mesoporous supports
(SAMMS), and as indicated by the ACOE, this is experimental
and currently confined to the laboratory bench.
Comment noted (experimental, confined to lab bench),
Frysell, et al., 2005 will be changed to Fryxell, 2005.
Noted
-------
40
41
42
HMC
HMC
HMC
5.3
6.2
7.2.4
30
32
38
The ACOE states that ion exchange resin cannot reliably
remove the cation form of selenium, selenite. Selenium will
not be present as a cation in the groundwater. Selenium
typically is found as selenate (SeO42"; with selenium in the +6
oxidation state) or selinite (HSeO3" or SeO32"; with selenium in
the +4 oxidation state) depending upon pH. All of these
forms of selenium are anionic.
An evaporation rate reduction of 50 percent in the ponds is
cited. However, HMC's research has found that the reduction
rate is lower at approximately 10 percent (Salhotra et al.
1985) for the salinity present in the evaporation ponds.
The ACOE provides details of improvements to the
presentation of data in the air particulate laboratory reports.
HMC has followed the standard reporting format required by
NRC for the laboratory reports.
Concur
Concur, in
part
Non-concur
Text will be modified.
From the brine and fresh water plots from M. Al-Shammiri
"Evaporation rate as a function of water salinity",
Desalination 150 (2202) 182-203, a freshwater evaporation
rate of approximately 120 gpm was inferred, with an
approximate reduction of 50% from fresh water to saturated
brine to 62 gpm. HMC cites a reduction of 10% based on
Salhotra et al. 1985. The reduction of evaporate rate is not as
important as actual passive evaporation rate from the ponds,
which was supplied by Homestake in the USACE site visit as
80 gpm. The text will be revised to indicate that the actual %
reduction of evaporation rate varies significantly in the
literature (10-50% in the two studies referenced). The text
will remain the same, though, indicating that use of the ~50%
reduction rate from the Al-Shammiri study yields an
approximate evaporation rate for the brine of 62 gpm, which
compares to the passive rate of evaporation measured by
Homestake of approximately 80 gpm. The text "The slightly
higher measured evaporation is most likely due to pond
water, particularly at the surface, not being completely
saturated." shall be removed.
Current NRC Guidance, including Regulatory Guide 8.30,
requires that results less than the LLD be reported, even if
negative. However, the report will be revised to indicate
that the laboratory data sheets in the July-December 2009
SAEMR no longer use
-------
43
HMC
9.3
47
The ACOE provides a list of six recommendations that should
proceed independent of any other recommendations. HMC's
view on each of these recommendations and how to proceed
are discussed in our responses as identified below:
1) the evaluation of the potential escape of contaminants at
the northwestern portion of the site (see Response to
Recommendation No. 3)
2) the evaluation of the former mill site as a potential source
of groundwater contamination (see Response to
Recommendation No. 4)
3) further characterization of the extent and migration of the
Chinle plumes (see Response to Recommendation No. 5)
4) complete decommissioning of potentially compromised
San Andres wells (see Response to Recommendation No. 7)
5) development of a comprehensive optimized monitoring
program (see Response to Recommendation No. 12)
6) implement treatment of contaminated irrigation water to
remove contaminant mass from the environment (see
Response to Recommendation No. 14)
Noted
See other comment responses.
44
NMED
1.1.2
Assessment of the adequacy of the Site monitoring network
(bullet #5) should also include evaluation of wells to monitor
the delineation between saturated and unsaturated
conditions in the alluvium, with emphasis on the potential
for contaminants to migrate from the southernmost alluvial
contaminant plume without detection.
The report will note the need to include a comparison of
measured water levels to the adjacent inferred top of rock
surface to assure the plume is adequately defined.
Concur
-------
45
46
47
48
49
50
NMED
NMED
NMED
NMED
NMED
NMED
1.4.3
1.4.3
1.4.3
1.4.6
2.1.2
2.1.3
4
4
4
5
6
6
Site contamination of concern for which ground water
remedial goals have been established include nitrate,
chloride, and vanadium. NMED notes that interpretation of
nitrate data may be complicated by agricultural activities
that occurred prior to and during legacy uranium activities in
the area.
The second to last sentence in the first paragraph compares
alluvial ground water data from 2.5 miles west of the site to
alluvial ground water data and the site to demonstrate
degradation of ground water quality. This is not an
appropriate comparison as the alluvial ground water data
taken west of the site is representative of San Jose alluvial
water, whereas the data for the site is San Mateo alluvial
ground water.
The first sentence in the second paragraph should read
"Water within the tailings piles..."
Note that EP-2 construction included a double liner with leak
detection
Another possible explanation for elevated contaminant
concentrations in the "1" series wells could be the result of a
concentration gradient.
Please qualitatively evaluate potential ecological risks from
the use of uncovered evaporation and collection ponds.
Concur
Concur
Concur
Concur
Noted
Non-concur
Section will mention these contaminants. The report noted
that there were other contaminants of interest not listed.
Though the statement of fact does not directly attribute the
increase in sulfate to Homestake, it does imply this. A
clarification will be made that the cause of the increase is
not clear
Change will be made to read as suggested.
Text will be revised
The nature of the "gradient" mentioned in the comment is
not clear. Presumably, they were suggesting a gradient from
the tailings pile. This is a possibility and the text will be
revised to mention this. There is little recent data for wells
between the mill site and the tailings pile. Well TB had
approximately 0.8 mg/L Unat in 2005, a lower concentration
than some of the 1 series wells.
The evaluation of potential ecological risks of evaporation
pond usage is outside of the scope the focused review. The
July 2008 Environmental Assessment completed by the NRC
for EPS included Section 4.1.5 discussing potential ecological
impacts from the use of the evaporation ponds.
-------
51
52
53
54
NMED
NMED
NMED
NMED
2.2
2.2.3
2.3
3.2
6-7
7
7
8
Although the surface water pathway is not complete,
periodic flooding due to heavy rainfall does occur.
Furthermore, one conclusion in this report is that
contaminant source waste materials (i.e., the tailings piles)
should remain on-site. Therefore, NMED herein reiterates an
earlier comment from the discussion of the scope of work for
this study that review of flood control structure constructed
for the long-term protection of the tailings piles must be
included within the RSE.
Although alternative water sources (i.e., hookups to the
Milan municipal water supply) have been offered to current
residents within the area of concern, which NMED has
defined based upon the surface areal extent of Site-derived
historical ground water contaminant plumes, there are
currently no mechanisms either to require such hookup for
current or future residents, nor to preclude the use and
installation of private wells within this area. Additionally,
current monitoring for potential site-derived impacts to the
San Andres aquifer is inadequate to document long-term
protection of this aquifer. For these reasons, NMED does not
agree with the assertion that the ground water pathway is
incomplete.
The last sentence should refer to figure 2 instead of figure 1.
Please move x-axis label to the bottom of figures 3, 4, and 8.
Noted
Concur
Concur
Concur
We defer to the agencies. Though such a study may be
appropriate, it is beyond the scope of this RSE effort.
Based on information in the 2009 Annual Groundwater
Monitoring Performance Review Report, Appendix E, Land
Use Review/Survey, five residential properties remain to be
provided a hookup as of March 31, 2010. We would
encourage the continuation of periodic assessment of water
usage, as required by HMC's NRC license and the testing of
San Andres wells. See also response to Comment 27.
The text will be corrected.
The readability of the charts will be improved in several
ways.
-------
55
NMED
3.6
16
The San Andres aquifer is an important municipal water
supply source to the nearby major population centers of
Grants, Milan, and Bluewater, as well as to residents using
private wells within the impacted subdivisions south of the
site. NMED asserts that routine and focused monitoring of
this aquifer, both upgradient and downgradient of the site,
should be included within the Remedial System to better
support an assertion of no contaminant impacts to this
aquifer from the overlying site-contaminated aquifers.
Noted
We agree the San Andres is valuable resource that needs to
be protected. Based on the available information in the
annual reports, a number of San Andres wells are included in
the monitoring program, including 1 upgradient well and 9
downgradient wells. If there are specific additional San
Andres wells that NMED is aware of that should be included,
we can note that in the report. In evaluating a comment
from Milton Head, it was noted that a couple of monitoring
points, 0943 and 0951, in the San Andres may have an
increasing U concentration trend. The cause for this is not
known.
56
NMED
4.1
17
The RSE team's argument for the discontinuation of the
Large Tailings Pile ("LTP") flushing appears to be incomplete.
NMED suggests that trends of contaminant concentrations in
effluent discharged to the collection ponds should be
evaluated and cited. Additionally, the heterogeneity of the
LTP materials could indicate that some portion of uranium
concentrations that do not respond to flushing (e.g.,
contaminants within slimes and other fine-grained materials)
mostly will remain in-situ, and therefore, may not
significantly impact alluvial ground water quality after
flushing of the more-accessible and mobile contaminant
concentrations within the LTP meets the flushing effluent
objective. The RSE team might consider whether 1)
continued flushing with reducing and/or low-alkalinity
solutions to "fix" remaining accessible contaminants in-situ,
and/or 2) deployment of an impermeable or an evaporative
cover to the LTP, could reduce additional contaminant
leaching from the LTP once draindown is complete.
Concur, in
part
We agree that fluids that remain following years of flushing
likely represent the less permeable materials. These
materials are likely to release pore fluids much more slowly
than the sandy material in the pile, but may still release
contaminated fluids over time if water head is not reduced.
Regarding the use of reducing and low alkaline solutions for
flushing, such techniques are similar to the concepts
evaluated in the RSE report for the soils below the pile.
There would be a need to show that geochemical changes
would be permanent, i.e. conditions would not revert to
original conditions over time, with increased dissolution of
uranium and selenium. We will add this concept to the text
in section 4.4.3, though will not specifically estimate costs
for this.
57
NMED
4.1
18
Tailings in Figure 15 is misspelled.
Concur
Chart heading will be corrected.
-------
58
NMED
4.1
19
The RSE team did not document evaluation of possible
alternatives to flushing of the LTP. Please provide and
evaluation of possible alternative actions, including a
comparative analysis of pump-and-treat at the toe of the LTP
during draindown, in-situ immobilization technologies, and
any other applicable alternatives.
Concur, in
part
As stated above, mention of immobilization of materials in
the pile will be qualitatively added to section 4.4.3. The RSE
team still believes the dewatering and covering of the pile, as
originally planned, represents a better end state for the pile.
59
NMED
4.1
19
The second sentence in the second paragraph on page 19
should acknowledge that draindown of the LTP may take
decades.
Text will be added.
Concur
60
NMED
4.1
19
The last paragraph appears to assume a trend of decreasing
contaminant concentrations after LTP flushing is
discontinued. While flow rates would likely decrease over
time due to termination of flushing, the RSE should address
the possibility that contaminant concentrations in ground
water may increase.
This possibility will be noted in the last paragraph of section
4.1.
Concur
61
NMED
4.2
19-20
The last sentence of the first paragraph on page 20
recommends injection of fresh water into the Chinle to
reverse the recharge (contamination) from the alluvium to
the Upper Chinle. NMED recommends that the RSE team
evaluate the possibility that this action may exacerbate
migration of contamination in the Upper Chinle.
The text will be amended to note the risks of loss of control
of the contamination in the Upper Chinle if injection is
implemented improperly.
Concur
62
NMED
4.3
20-23
The reliance on "existing liner (sic) under pond wastes" for
long-term waste isolation may be inappropriate due to the
observed and presumed deterioration of these mostly single
liners over the ponds' usage period. Additionally, NMED
recommends that the RSE team define the term "highly
effective cap" within the context of long-term waste
isolation.
Non-concur
The observed deterioration of the liners is most likely related
to the exposure of the liner along the pond berms to sun and
traffic of various kinds. The continuously submerged portions
of the liners (that are also covered by precipitates) would not
be subjected to the same conditions. The report does
acknowledge the potential for leakage of the liners and
suggests a method to assess leakage.
63
NMED
4.3
20-23
No alternative methods of evaluation were discussed to
determine of ponds were leaking other than investigative
methods.
The RSE team does not have other methods to suggest.
Noted
-------
64
NMED
4.4.1
23
The proposal for deployment of slurry walls does not address
the long-term objective to achieve ground water protection
standards through establishment of stable, self-sustaining
site conditions without ongoing maintenance requirements.
NMED recommends that the RSE team attempt to quantify
the length of time and associated costs for such maintenance
as would be required under this proposal, in the same
manner that the proposal for permeable reactive barrier
emplacement is evaluated in the section following the
discussion of this option in the report.
There will be monitoring required to assess the slurry wall
performance over time, but maintenance is negligible. The
text will note the need for monitoring of water levels, but
the cost for this is not significant. Slurry walls are generally
considered to be very long-term components of a remedy.
Concur, in
part
As noted above, the RSE team might evaluate whether in-situ
immobilization technology could be appropriate to LTP
flushing.
65
NMED
4.4.3
25
Noted
Several types of in-situ immobilization technology was
evaluated by the RSE team and found to be infeasible
because of the large variation of pH at the site, which creates
a different and diverse set of uranium ionic species for
which stabilization treatment conditions have not been
established. The cost to implement was also pointed out as a
barrier. However, in-situ mobilization is currently occurring
for the selenium, and to a more limited extent, by the
current flushing regime where the reinjected water becomes
reducing from passing through the residual slime in the LTP.
The effect of the more reducing conditions is removal of the
selenium, and potentially some of the uranium, from the
groundwater. However, this in-situ mobilization may not be
permanent when the flushing is stopped as more oxidative
groundwater movement through the LTP may make the
aquifer matrix more oxidative, with a resultant
remobilization of the selenium and uranium. This language
will be added to the text.
66
NMED
4.4.4
27
For consistency, the RSE team should employ similar AFCEE
sustainable Remediation Tool analysis of other proposed
remedial options.
Concur
This comment was addressed in a special addendum issued
in June, 2010.
-------
67
NMED
6.3
32
The original RSE report identified persistent operation and
maintenance issues affecting the operation and maintenance
of the evaporative sprayers. NMED recommends that the
RSE team examine whether any different equipment and/or
deployment strategies are available that could address these
issues to enhance evaporation.
The team did not assess alternative equipment.
Noted
68
NMED
6.3
33
The last paragraph states 180 gpm as the proposed flow of
wastewater into the evaporation ponds for disposal. This
flow assumes the L TP flushing program is discontinued, but
does not account for flows from the toe drain collection
wells.
The analysis assumes that 65 gpm will be derived from the
drains/sumps.
Non-concur
69
NMED
7.1.1
34
Documentation of the protection of the San Andres aquifer
from impacts derived from the overlying contaminated
aquifers should be an important component of the overall
monitoring strategy for the Site.
Noted
The current RSE addresses the status and risk to the San
Andres. The primary risk is through improperly completed
wells. The report encourages the proper decommissioning
of unused San Andres wells within the footprint of the
plumes.
70
NMED
7.1.2
35
An important component of a critical re-evaluation of
Homestake's monitoring system should be appraisal of each
monitor well's completion documentation and current
condition to ensure that samples from each well accurately
reflect the ground water quality within the aquifer that is
presumed to be monitored.
Noted
Such a well-by well evaluation of such an extensive network
of monitoring wells is beyond the scope of this RSE. In some
cases, the screened intervals of the wells were noted as part
of the analysis, and the impact of this information was
considered, as was the case with the wells in the large
tailings pile.
71
NMED
7.1.2
35
Additional monitoring wells located at the confluence of the
San Mateo and Rio San Jose alluvial systems to monitor the
stability of ground water conditions within the alluvial
aquifer should be considered.
Non-concur
There are a number of alluvial wells located in this area,
though not many are sampled. Periodic but infrequent
monitoring of additional available wells in the western
portion of the study area may be appropriate.
72
NMED
8.1.1
40
The RESRAD modeling should be updated with current data
which indicates contaminants have migrated in the irrigated
soils well beyond 1 meter vertically.
Concur
The RESRAD inputs will be reevaluated in response to this
and other stakeholder comments. Specifically, the depth of
contamination will be estimated using Figure 3-14 from the
HMC 2009 Annual Irrigation Evaluation.
-------
73
NMED
8.2
42
It must be noted that the New Mexico Water Quality Control
ground water standard for selenium is 0.05 mg/l, not 0.12
mg/l.
Noted
The report will be revised to clearly indicate that the 0.12
mg/L was a site-specific selenium value based on background
and that the current NMWQC standard for ground water is
0.05 mg/L. See also, NRC Comment 117 below on the
application of water quality standards to irrigation water.
74
EPA
General
Considering the scope of work, time and budget constraints,
the USACE has done a commendable job in evaluating this
complex site and provided some practical recommendations.
Thank you
Noted
75
EPA
General
The report is well written and addresses the issues at length
that were important to the stakeholders.
We certainly tried.
Noted
76
EPA
General
11-15,
18, 19,
21,22
The graphs in the report should be reformatted, especially
the x and y axis descriptions to better illustrate the data
trends.
The charts will be improved
Concur
77
EPA
General
Include additional figures wherever possible to show location
of wells for better understanding of the remedial system.
Figures added where we could
Concur
78
EPA
3.4
15-16
I agree with concern about the modeling approach for
projecting uranium (and other contaminant) concentrations
in the Large Tailings Pile (LTP) water under the currently
implemented and projected flushing strategy. In line with
the recommendation to curtail the current flushing
operation, I recommend implementing a pilot test prior to
2012 to examine the potential for contaminant
concentration rebound as a result of the cessation of
flushing.
We agree a pilot test would be an important contribution to
our understanding of the long-term conditions in the pile
and will add this to our recommendations.
Concur
-------
79
80
81
82
EPA
EPA
EPA
EPA
4.2
20
36
i-iv
1
With regard to aquifer solids, clays and oxyhydroxide
minerals are commonly the primary solid components to
which metals and radionuclides will partition within the
alluvium. Existing information on sorption characteristics of
the impacted alluvium may be available through analysis of
information presented in ATTACHMENT A - ALLUVIAL
AQUIFER RETARDATION AND DISPERSION TEST RESULTS
(GROUND-WATER MODELING FOR HOMESTAKE'S GRANTS
PROJECT, Hydro-Engineering, L.L.C., April 2006).
1 recommend caution with regard to the suggestion of "no-
purge sampling" as an option for metals/radionuclides
sampling from the HMC network of wells. If this
recommendation is pursued, 1 recommend that a
comparison of analytical data first be conducted for a subset
of site wells prior to switching to this type of a sampling
device. 1 would anticipate for collection of
metals/radionuclides samples the accumulation of mineral
precipitates within the well casing that may be dislodged and
entrained within the sampler. One diagnostic to determine if
this condition exists for well screens at the HMC Site is to
periodically pull up and examine dedicated sampling devices,
e.g., flexible polyethylene/teflon tubing or in -well pumps. If
there are precipitate coatings on the device at the depth of
the well screen, then 1 would be cautious about using a no-
purge sampling device.
Be consistent with the use of periods at the end of bulleted
sentences/phases. Some sentences/phases have periods
while other do not.
Add "with the current remedial strategy" to the end of the
sentence.
Concur
Concur
Concur
Concur
Will add discussion based on the attachment.
We will add these cautions to the text.
Text will be revised.
Text will be revised.
-------
83
84
85
86
87
88
89
90
91
92
EPA
EPA
EPA
EPA
EPA
EPA
EPA
EPA
EPA
EPA
2.2.1
2.2.2
Figure 1
Figures
1
v-vii
2
5
7
7
9
11
17
18
3rd paragraph, sentence beginning with "The analysis...".
Change "at the USAGE EM CX" to "by the USAGE EM CX".
Be sure to align page numbers to the right. Currently
numbers are scattered across pages.
Substitute "Robert Ford" for "Michele Simon". Michelle is no
longer involved in the project.
Please update the last statement on page 5 regarding the
approval of the new evaporation pond on the north side of
the LTP. NMED has recently approved the discharge permit
for the new evaporation pond.
first sentence. Change 'human' to humans"
first sentence. Change 'and' to 'can'.
Add a figure that clearly indicates monitoring well locations.
1 can not identify monitoring wells referenced in the report
on this figure.
Please check the labels on the x and y axes - the dates and
other units are not correctly located or easy to read. Please
reformat figures to allow for accurate reading of the x and y
values.
last paragraph, 3rd sentence. Change 'has' to 'have' and
change figure to "Figure 15 in the same sentence.
paragraph in the middle of the page regarding additional
testing of oxidation-reduction potential. Please elaborate on
the types of add'l testing that would be necessary and how
the data should be interpreted.
Concur
Concur
Concur
Concur
Concur
Concur
Concur
Concur
Concur
Concur
Text will be revised.
Text will be revised. The text alignment was apparently
altered in the conversion to Acrobat format and wasn't
noticed until it went out.
Text will be revised.
Text will acknowledge this.
Text will be revised.
Text will be revised.
We will attach a separate file in 11x17" format such that it
can be more easily read.
Text will be revised.
Text will be revised.
We will elaborate to indicate that downhole ORP and pH
measurements would be useful to assessing the likely state
of the U in the pile and the impacts from the flushing
program on the stability of the U.
-------
93
EPA
19
2n paragraph. Please clarify the "average saturated
thickness" mentioned regarding the calculation of natural
flow. Please include the thickness of the various aquifers at
least by reference.
Text will be revised.
Concur
94
EPA
20
2n paragraph. Please add information regarding how the
boundary for active pumping vs. natural attenuation should
be determined. Please discuss the need to use modeling or
other lines of evidence to help quantify this boundary.
Currently, the statement regarding use of the current
extraction wells as the cut off point between capture and
natural attenuation seems arbitrary.
The text indicates that the wells are near the limit of the
plume defined by the 0.16 mg/L concentration and in good
locations for capturing the plumes.
Non-concur
95
EPA
20
3r paragraph. Please elaborate on the types of additional
study required to assess unusual water levels.
Concur
Additional discussion regarding the possible considerations,
such as the examination of hydrographs, verification of top
of casing elevations, assessment of transcription error in
field notes.
96
EPA
21
1s paragraph. Has it been confirmed that the 100 foot error
in the C series wells is in fact in error or are you assuming
that it is an error?
Noted
HMC comments indicated that this measurement was an
error that has been corrected.
1st paragraph. Double periods at the end of the paragraph.
Text will be revised.
97
EPA
23
Concur
98
EPA
23
2n paragraph. Double periods at the end of the first
sentence.
Text will be revised.
Concur
99
EPA
23
Table 1. Please create table with gridlines and align
numerical values left or right. Currently I believe they are
centered and it is awkward to read. - same goes for Table 2
on page 25.
Text will be revised.
Concur
-------
100
EPA
In the recommendation on slurry wall construction, USAGE
should consider deleting the last sentence "The decision for
implementing such an alternative would depend on the
economics of the situation" or adding additional clarification.
It is not clear why only this alternative would depend on the
economics and not the others.
Non-concur
The primary benefit of the slurry wall would be to reduce the
amount of pumping necessary to prevent lateral or vertical
contaminant migration. As noted in the report, the presence
of permeable bedrock below a portion of the alignment/pile
would require some pumping to prevent migration. If
pumping and treatment are still needed, the capital cost of
the slurry wall would have to reduce the life cycle cost of the
treatment to be justified.
101
EPA
27
Regarding the recommendation of relocation of the tailings
the USAGE should consider evaluating additional potential
hazards from moving the tailings pile besides the CO2
emissions and fatalities. Are there other practical risks from
moving the pile?
Concur
Other potential risks include increased radon emissions and
potential for dust releases, though engineering controls may
mitigate these risks.
102
NRC
General
In general, the draft report appears not to provide a strong
basis for decision-making because of limitations in the
analysis and because it does not compare current
remediation strategies to those that are recommended. As a
result it lacks the information necessary to show how the
revised strategy will be more efficient and/or effective at
achieving site closure goals.
See Response to Comment 103 below.
Noted
103
NRC
General
various
Technical conclusions made in the report are routinely
qualified with "may be", "it appears", or "likely" which
detracts from the usefulness of the document because it
introduces uncertainty about the effectiveness of the
proposed remedies due to a lack of data, or a lack of time to
fully assess the hydrologic system. Pursuing changes to the
current remedial strategy with this level of uncertainty
seems unwarranted. Specific comments supporting this
conclusion are provided below.
Noted
Regarding this and the previous comment, in any analysis
such as this, with limited budget and time, there is always
the potential that other unknown or unrecognized factors
may affect the validity of the recommendations. We offer
our recommendations, albeit with hedges, in the spirit of
improving the project and spurring further consideration by
those on the project team that know the site and its history
the best.
-------
104
NRC
2.1.2
Section 2.1.2 identifies the location of the former mill
buildings as a potential source of contamination to the
ground water. However, there is very little basis provided
for such a conclusion. This section states there is "some
suggestion" in ground water monitoring data for this
conclusion. It goes on to say that the elevated uranium
levels in the 1 series wells have been observed but that the
"nature of the source is unclear."
Non-concur
The uranium concentrations in monitoring wells near the
former mill location appear to be elevated relative to the
surrounding area. While such a correlation would strongly
suggest a causal relationship between the contamination and
past mill operations, sampling data is somewhat sparse in
the area and other causes such as migration from the tailings
pile can not be ruled out. If a continuing source of
contamination were to exist at this location, it would affect
the time frame of achieving site ground water goals and
should be addressed.
105
NRC
3.1
Section 3.1 states, "Capture is not apparent for the irrigation
pumping in the downgradient portions of the uranium and
selenium plumes, nor is it clear from available data that
capture of the plume along Highway 605 east of the site is
maintained." Based on this statement, the reviewers should
not draw any conclusion about the adequacy of plume
capture.
The statements made in the report are appropriate given the
available data.
Non-concur
106
NRC
3.4
15
The report states, "The primary concern with the modeling
conducted for the site is the simulation of the seepage of
contaminated water from the large tailings pile. From the
available information on this step in the modeling process, it
appears the modeling did not account for the likely
heterogeneity and preferred pathways for water injected
into the tailings. It seems likely that the
flux of water is not uniform through the pile and that large
volumes of the pile still have a significant amount of their
original pore fluids. The model likely over-predicts the
performance of tailings flushing."
The report does state this. We will strengthen the
statements.
Concur
107
NRC
4.1
17
"..heterogeneity of the materials has likely prevented.."
"..makes it difficult to assess.."
"It is not obvious the flushing program would meets its goal
by 2012.."
We will strengthen the statements.
Concur
-------
108
NRC
4.4.1
23
"This would potentially reduce the long-term costs for the
operations, possibly significantly."
Non-concur
We can not say with certainty and it was beyond the scope of
our effort to provide detailed cost analysis of the impact to
the costs for operating the plant.
109
NRC
7.1.4
36
"The use of no-purge sampling techniques, such as
Hydrasleeves and Snap samplers may be considered to
reduce the time necessary to sample the wells." The use of
no-purge sampling was not determined to be a time saving
or cost savings alternative to the current sampling
methodology utilized by Homestake.
Non-concur
If the well conditions are appropriate, as noted in the EPA
comments, such no-purge techniques can give good results
with reductions in field time. The NRC does not provide a
citation for an analysis done to assess the costs or time
necessary for no-purge sampling.
110
NRC
7.2.2
37
"The number and location of control monitoring stations
may not be adequate to meet the overall objective of
ensuring compliance with the public dose limit in 10 CFR
20.1301."
Given that the NRC staff has previously determined that the
number and location of control monitoring stations is
adequate, the reviewer should provide additional
justification for its statement.
Non-concur
As indicated in your Comment 114 below, the determination
of an appropriate radon background and decay progeny
equilibrium ratio are important and challenging to
determine. The HMC July-December 2009 SAEMR indicated
that the single radon background location HMC #16 result for
the period was an anomaly (significantly higher than
previous readings) and that they have initiated a study to
confirm that location as an appropriate radon background.
We encourage NRC to work with HMC to determine an
accurate distribution of radon background for use in their
compliance calculations.
Ill
NRC
4.2
19-20
The NRC staff does not agree with the statement, "...injection
of relatively clean water from other aquifers into the alluvial
aquifer downgradient of the site at rates that exceed
extraction complicates the control of the plumes and may do
more to dilute the plume rather than treat it." We believe
injection is necessary because the hydraulic control cannot
be maintained in the unconfined alluvial aquifer by
extraction alone. The number of extraction wells and their
pumping rates would have to be increased to maintain
hydraulic control to an area of this size.
USACE should re-evaluate the recommendations in this
section.
We stand by our evaluation.
Non-concur
-------
112
NRC
7.1.5
36
Optimization tools mentioned in this section should have
been used for this evaluation for a limited data set, at
minimum, to provide a basis for recommended changes to
the groundwater and air monitoring programs.
Non-concur
The application of these tools to a subset of the site would
not be within scope or all that helpful - the monitoring
program should be assessed holistically. The tools have been
well documented at other sites and we believe would be
beneficial to the Homestake site. For more information,
refer to the EPA/USACE document cited in the report or visit
http://www.frtr.gov/optimization/monitoring.htm.
113
NRC
7.2.2
37
Section 7.2.2, refers to the "large area potentially impacted
by the Homestake effluent releases". The report should
specify what area is impacted by the Homestake tailing piles
radon releases. The Shearer and Sill surveys (Health Physics,
17 (1), pp. 77-88) of radon-222 concentrations in the vicinity
of uranium mill tailing piles, appear to conclude that no
statistically significant difference between measured radon-
222 concentrations around tailing piles and background
radon-222 levels could be discerned beyond a mile from the
tailing piles.
The paragraph in the report will be modified to clearly
separate out the effluent releases into particulate and radon
and a reference to historical radon studies will be included.
See also, Comment 110 above.
Concur, in
part
114
NRC
7.2.2
37
The methods in US NRC Regulatory Guide 8.30 for radon-222
daughter measurements are better suited for assessment of
worker's exposure to radon daughters indoors, and most of
these methods may not be appropriate for determining
either outdoor radon progeny levels or an equilibrium factor.
The determination of a radon background level and an
appropriate radon & radon progeny equilibrium factor are
especially important and challenging to determine.
Concur
Agree with the commenter regarding the importance of
determining appropriate radon background levels and
radon/radon progeny equilibrium factor. Agree that the NRC
methods referenced in the draft report may not adequately
capture the diurnal, seasonal, and other atmospheric
variations in outdoor radon progeny concentrations and the
report will be revised to recommend that NRC work with its
licensee to ensure that appropriate methods are identified
and used to confirm the progeny equilibrium factor currently
assumed by HMC.
-------
115
NRC
8.0
40
Although efforts were made to take a conservative approach
to modeling this site, RESRAD was not designed to be used to
evaluate doses from contaminated irrigation water. There
are other computer codes (e.g., GENII) that can be used to
evaluate doses associated with irrigation. Other options,
such as the Radium Benchmark Dose, which is discussed in
40 CFR 192 and 10 CFR 40, Appendix A, Criterion 6(6) could
also be used.
Noted
The RESRAD model, though not specifically designed to
address irrigation with contaminated water, was used as
described in Section 8.1.1 to estimate the dose and risk from
water dependent ingestion and radon inhalation pathways.
The EPA is currently planning for and gathering additional
data to support a more detailed human health risk
assessment.
116
NRC
8.0
40
Some RESRAD parameter values may impact the dose
received by the future resident such as the use of 400 acres
(1.6E+6 m2) of soil irrigated with contaminated irrigation
water. It is unlikely that a single individual would be exposed
to the entire area while living on the site. Consideration of
soil dilution associated with the construction of a house with
a basement can further decrease the amount of
contaminated soil a future resident may be exposed while
the increase in time spent outside from 25% to 50% of the
future resident's time may increase the dose. When
evaluating the dose to a future resident it is also important
to include all relevant exposure pathways (e.g., external
exposure, inhalation, ingestion, and radon) associated with
the site.
Concur, in
part
The RESRAD inputs will be reevaluated in response to this
and other stakeholder comments. Specifically, the area of
contamination will be reduced to the RESRAD default of
10,000 square meters. For this conservative assessment,
dilution of soil from basement construction is not considered
and the receptor is modeled to be present at the site 100%
of the time split evenly between indoor and outdoor
activities. As shown in Tables 5 and 6 of the draft report, all
relevant pathways were included in the assessment.
117
NRC
8.2.1
42
There is no basis for applying the New Mexico water quality
standards for irrigation water. Removal of contaminants
prior to irrigation would defeat the purpose of this
remediation strategy. In addition, this section implies that
the current practice of directly applying untreated extracted
groundwater for irrigation is done with effluent
concentrations above discharge standards. Groundwater
used for irrigation has been below the discharge standards
required by Homestake's license, which is based on 10 CFR
20, Appendix B, Table 2 values.
The application of specific standards is the responsibility of
the regulatory agencies. See, NMED Comment 73 above. As
stated in the report, the treatment alternative was
developed in response to stakeholder concerns and to
provide regulatory agencies treatment information,
regardless of the driving reason.
Concur
-------
118
119
120
121
122
NRC
NRC
BVDA
(M.Head)
BVDA
(M.Head)
BVDA
(M.Head)
8.2.2
9.1
43
44
Section 8.2.2 indicates that uranium leaching into
groundwater is not considered to be a likely risk. If the risk is
small, and Homestake is meeting its regulatory
requirements, how will the suggestions offered to reduce
uranium mobility in the irrigated soil make the current
decommissioning strategy more efficient and/or effective at
achieving site closure goals?
Bullet number 1 of Section 9.1 states that ground water
remediation is very unlikely to be achieved by 2017. The
basis for this statement is unclear since the RSE addendum
did not determine an estimated remediation date for the
current remediation strategy nor did it provide an estimated
remediation date for the implementation of the
recommended changes.
Stop flushing the Large Tailings Pile.
The injection and collection system is extracting a very very
small part of the total contaminants. From 1977 to 1990 data
shows there was no extraction of contaminants. The water
collected was returned to the Large Tailings Pile. Since 1990
to 2010, approximately 210 gpm of contaminated water is
being collected and stored apparently into one of the three
evaporation ponds. The contaminants are being diluted not
extracted. If Homestake/BG is allowed to drill the 39 new
wells, they will be pumping 3,642 gpm while only 210 gpm is
being treated, then only .0577% of water pumped out of the
ground is being treated by extraction. This current method of
remediation of H/BG site and surrounding area will cause a
4,500 to 8,000 acres tailings pile to the created.
There must be monitor wells drilled below the original mill
site and water tested.
Noted
Non-concur
Noted
Noted
Noted
The intent of the analysis of treatment options for the
irrigation water was to assess what would be required in
order to address stakeholder concerns and EPA's preference
for treatment.
Our basis is provided in section 4.1.
The report recommends this.
There are a number of alluvial wells located in this area
already. Assessment of historical operations would help
identify where releases may have occurred that would
represent a significant source.
-------
123
BVDA
(M.Head)
Middle Chinle - Based on data from February 2,1960 to May
1978, of 73 monitoring points, 32 have tds data. The average
tds was 1149. (See Milton Head Exhibit I attached).
Noted
124
BVDA
(M.Head)
Use USGS resistivity flights to identify all aquifers. (See
Milton Head Exhibit II attached).
Noted
125
BVDA
(M.Head)
There is data on San Andres wells. History of San Andres
shows many San Andres wells are showing increase in tds
and uranium. (See Milton Head Exhibit III attached).
Concur, in
part
The data for the HMC deep wells do not show an increase,
but in examining the U data for well 0943 and 0951, there
may be some evidence for an increase, but the cause is not
known. Well 0951 is not likely to be impacted by the site as
it is far upgradient.
126
BVDA
(M.Head)
There is data available concerning upgradient water. There
was testing done as early as 1962.(See Milton Head Exhibit IV
attached).
Concur
The information provided by Mr. Head indicates that near
what is now the northwest corner of the large tailings pile,
sulfate was measured as under 700 mg/L, but is now more
than double that, as shown in the 2008 Annual Report. This
will be mentioned.
127
BVDA
(M.Head)
Construct EPS and put anything left over from RO extraction
into EPS. The addition of EPS should eliminate the need for
spraying contaminants into the air and spreading them
around the area.
Noted
One of the calculations in the RSE assumes discontinuing all
evaporative spraying and calculates the surface area of new
pond necessary to achieve this. No further changes were
made to the changes of the document
128
BVDA
(M.Head)
There should be no expansion of small tailings pond near the
existing STP. Put EPS into operation.
A slurry wall can be used to isolate the LTP and STP. The
technology is available. There would have to be a study to
include concept, engineering, feasibility and cost. This does
not preclude the need to move the LTP and STP. These piles
can be moved through a slurry pipe, dried down and placed
in a shale or clay geological formation with no risk to
community or public. Moving the tailings piles is no more of
a threat to the public health than any operating uranium mill
tailings. The only hindrance is the decision to move them and
the money needed. However, slurrying the pile to safe
permanent storage minimizes the potential for pollution as a
result of the move and risk to workers.
Concur, in
part
The report will be modified to remove the suggestion to
expand the pond on the small tailings pile and will
acknowledge the approval of EPS. The report discusses the
use of a slurry wall, including the cost, advantages and
limitations. An analysis of the potential to move the tailings
via slurry pipeline will be added. Note that there are
potential impacts of opening the tailings pile for transport,
including increased radon release and contaminated dust.
Slurry transport will mean the export of water from the
vicinity of the site to the repository site, even if most of the
water is returned via separate pipeline. This means less
water in the alluvial aquifer near the site.
-------
129
130
131
132
133
134
135
BVDA
(M.Head)
BVDA
(M.Head)
BVDA
(M.Head)
BVDA
(M.Head)
BVDA
(M.Head)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
2
2
Develop a comprehensive, regular and objectives-based
monitoring program.
Allow irrigation rather than injection wells. This will allow
observation of the success of extraction methods.
H/BG quotes large number of pounds of uranium and other
constituents being removed from the ground waters - locate
and identify these constituents. There should be a regular
semi-annual analysis of the water and solids in the existing
evaporative ponds.
Well X- dilution is not clean up so quit playing games with
WellX.
Leaving uranium in an unlined tailings pile with as much
water as the LTP has means it will continue to seep into our
water forever even with a cover.
The DRSE Report should be revised to present a higher
estimate of uranium remaining in the tailings following mill
operations. The estimate of uranium in the tailings piles
should be revised upward by at least 100 percent, to the 4.8
- 6.6 million pound range, based on available technical
literature reports addressing uranium remaining in tailings
from the HMC site mills.
To the extent that one of the goals of the HMC remediation
system is recovery or stabilization of the mass of uranium in
the tailings, it seems to be extremely important to establish a
conservative estimate of the baseline of uranium in the
tailings based on site-specific data. Such an estimate is likely
to be at least twice the estimate of uranium remaining in the
tailings in the DRSE Report.
Noted
Non-concur,
in part
Non-concur
Noted
Non-concur
Non-concur
Non-concur
We are not sure if the comment supports the use of
irrigation with treated water or just the use of irrigation with
untreated water. We do support the reduction in the use of
injection wells.
There is sampling of the brine in the ponds, from what we
understand, but the sampling of the solids raises many
issues, including the potential to harm the liner during
sampling, the variability of concentrations in the solids
laterally and vertically. The measurement of the influent and
effluent concentrations actually is the best way to determine
the mass that is going/has gone into the ponds.
The text will note the impact from injection on
concentrations in Well X.
Though the impacts are likely to extend over a long period of
time, it would not be forever.
The analysis presented in the report adequately makes the
point that a substantial quantity of contaminant mass
remains in the pile. The basis for the mass estimate is
presented in the report. We understand there are other
estimates of the mass in place.
See response above.
-------
136
137
138
139
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
2
2
3
3
Though not a concern identified at the beginning of the RSE
process, the DRSE Report should be revised to address
HMC's technical approach, which emphasizes removal of
uranium in solution in the tailings and considers the uranium
not in solution to be relatively immobile and not likely to leak
out of the tailings.
The DRSE Report should be revised to address, or comment
generally on, the likely distribution of uranium remaining in
the tailings between portion of uranium that may be
dissolved in liquids in the large tailings pile and the
remaining uranium not dissolved in liquids. The DRSE Report
should also be revised to evaluate the effectiveness of the
HMC remediation system to recover either or both portions
of uranium remaining in tailings.
The graphics in the DRSE Report should be enhanced to
identify key locations such as wells and pond sites, identify
key geological and land use features, and provide more
readable graphs of contaminant concentrations over time so
that vertical scales are similar, rather than a selection among
arithmetic and logarithmic scales, and check that the dates
for data reported are readable.
The DRSE Report should be supplemented to identify
methods or techniques to identify and address a potential
flow path in the area of those wells west and north of the
large tailings pile.
Concur
Noted
Concur
Non-concur
This will be mentioned in section 2.
See response to the above comment. The report does
already note the fact that much mass remains (and will
remain) in the pile following the cessation of injection.
Graphs will be improved, and the site figures will be made
available as 11x17 inch size to improve readability.
The report raises the question and we defer to the agencies
and stakeholders, including Homestake, to determine if
additional investigation is necessary and by whom. The
upgradient location of well DD suggests another cause other
than the tailings pile.
-------
140
141
142
143
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
3
3
3
3
The DRSE Report should be supplemented to identify specific
additional investigations, such as borehole installations, non-
intrusive geophysical methods, ground water control
systems or other measures to identify and address the flow
path in the well DD and Sll area.
The DRSE Report should be supplemented to include an
assessment of the effect of the consistent rising trend in
uranium concentrations in well DD on the value of a well at
or near the location of well DD as the single down gradient
monitoring well for ground water conditions for proposed
pond EPS.
The DRSE Report should be supplemented to address the
location of well DD and its associated flow path within the
footprint of proposed evaporation pond 3 (neither well DD
or EPS are identified on Figure 1) and the challenges to
investigation and remediation of the ground water with
rising uranium content in the well DD/well Sll area north
and west of the large tailings pile.
The DRSE Report should be supplemented to address the
extent to which the elevated uranium in wells DD and Sll
and the flow path that may be associated with them occurs
under or down gradient of proposed pond EPS. Illustration of
the location of wells DD and Sll, the extent of fault zone on
the west side of the large tailings, the extent of the alluvial
aquifer and proposed location of EPS would demonstrate the
relationship of these features at the site.
Non-concur
Non-concur
Non-concur
Non-concur
See response above.
We defer to the agencies. Though such a study may be
appropriate, it is beyond the scope of this RSE effort.
See response above.
See response above.
-------
144
145
146
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
3
3
3
The DRSE Report should be supplemented by the
identification of recommendations regarding future
investigations to determine variations in ground water flow
rates and the pattern of contaminant concentrations in the
fault zone on the west side of the large tailings pile
compared to less fractured portions of the aquifer occurring
in that fault zone, to define the ground water flow path in
that area.
The DRSE Report should be revised to include recognition of
the extensive injection well operation within a few meters of
monitoring well X and the "almost instantaneous change" in
uranium and sulfate concentrations in that well in 1994
when the injection system began.
The DRSE Report should be revised to reflect the likely effect
of these long-term injections of clean water on the uranium
concentrations in well X. The DRSE Report should also be
revised to address the data in the "Concentration Trend"
spreadsheet as a demonstration that the reduction in
uranium concentrations in well X is attributable to dilution
resulting from injection of clean water rather than
demonstration some sort of reduction in uranium
concentration due to uranium removal or control in the
alluvial aquifer.
Noted
Concur
Concur
Based on the comment, the water levels in the Middle Chinle
and the Alluvium, as reported in the 2008 Annual Report,
were compared. The West Fault does provide the potential
for enhanced permeability in the Middle Chinle (and possibly
the Chinle shaly intervals). The subcrop of the Middle Chinle
is exposed to contaminants in the alluvium, and there is a
downward gradient at the subcrop. The West Fault does not
appear to allow significant vertical communication with the
Middle Chinle on the east side of the West Fault, based on
the significant differences in water levels. It also seems
unlikely that the fault would allow northerly transport, as the
head gradient in the Middle Chinle and the alluvium would
appear to be to the southwest. The faulting would not
appear to explain detections northwest of the tailings pile.
The faulting may enhance southwestly movement in the
Middle Chinle however. No changes to the report were
made.
The text will note the impact from injection on
concentrations in Well X.
See above response.
-------
147
148
149
150
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
3
3
3
3
The DRSE Report should be revised to demonstrate that
monitoring well X ceased being a well capable of monitoring
seepage from EP1 when injection of clean water into nearby
wells began only four years after the 1990 installation of EP1.
The likely influence of injection of clean water on the data
generated at monitoring well X was a point of discussion
during the recent NMED hearing on HMC DP-725. While
NMED's recently issued final Discharge Plan DP-725 retains
monitoring well X as the sole monitoring well down gradient
of the four ponds, EP-1, EP-2, and the East and East
Collection Ponds, witnesses for all parties recognized that the
ground water concentrations at monitoring well X are
"influenced" by injection and collection wells near it, as
noted below. [Hearing citations not excerpted here.]
The DRSE Report should more accurately and effectively
address the effectiveness of monitoring well X. The DRSE
Report should also be revised to evaluate the significance of
the influence of the injection wells and other aspects of the
HMC injection and collection well system on uranium
concentrations detected in monitoring well X.
The DRSE Report should be revised to include an evaluation
of the adequacy of monitoring well X to demonstrate "plume
capture" and detect contaminants leaking from the small
tailing pile, or EP1 on top of the pile, or the other ponds and
tailings pile, because of the influence of injection well water
on the uranium concentration trend in monitoring well X.
Concur
Noted
Concur
Concur
The text will note the impact from injection on the ability of
Well X to detect leakage from the ponds.
See above response.
See above response.
-------
151
152
153
154
155
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
3
3
3
3
3
The DRSE Report should be revised to address whether
monitoring well X is located in a flow path that could detect
seepage from the East and West Collection Ponds, EP-2 and
EP-1 independent of the injection of clean water. If no flow
path from the ponds to monitoring well X can be identified,
the DRSE Report should be revised to identify a measure
recommended by the RSE contractors to establish a more
effective monitoring well in the south side of EP1, the other
ponds south of the large tailings pile and the small tailings
pile.
The DRSE Report should be revised to recommend additional
monitoring well sites at locations not compromised by clean
water injection, as is the case with well X, or rising uranium
trends, as is the case with monitoring well DD, be identified
to more effectively monitoring the current and near-term (10
yrs+) potential leakage from the four ponds.
The DRSE Report should be revised to address the adequacy
of the monitoring well and point of compliance well pattern
in place at the HMC site and identify alternative monitoring
well locations in recognition of the sources of dilution of
uranium at well X and the rising uranium concentration trend
at well DD.
The DRSE Report should be revised to more fully address the
implications and consequences of the over prediction of
flushing performances and identify recommended actions to
respond to the HMC ground water model's over prediction
of flushing performance.
The DRSE Report should be revised to identify the degree to
which performance of flushing has been over predicted.
Non-concur
Non-concur
Non-concur
Non-concur
Non-concur
Given the extensive monitoring network and sampling
program, the impacts of the actions in the alluvial aquifer at
the site can be reasonably evaluated. We defer to the
agencies for designation of the appropriate compliance
points.
See above responses.
See above response.
The report does address the consequences of the over
prediction. Additional evaluation is beyond the scope of the
study.
Additional evaluation is beyond the scope of the study.
-------
156
157
158
159
160
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
3
3
3
3
3
The DRSE Report should be revised to identify mechanisms
for more accurate prediction of flushing performance and
the consequences of more accurate assessed flushing
performance including, but not limited to, the likely ground
water conditions and distribution of uranium and other
contaminants in the large tailings pile if flushing is more
accurately predicted.
The DRSE Report should be revised to identify the
parameters in the HMC ground water model that lead to
over prediction of flushing effectiveness and options for
revising or recalibrating applicable models the models to
provide more accurate predictions.
The DRSE Report should be revised to include additional
graphic information to identify the extent of the Middle
Chinle and other aquifers on site and indicate where the
Middle Chinle aquifer may be either used or affected by
seepage from the tailings piles on the HMC site.
The DRSE Report should be revised to identify activities and
investigations necessary to overcome the lack of accuracy
regarding the hydrology of the Middle Chinle aquifer.
The DRSE Report should be revised to identify the
significance of understanding the hydrology of the Middle
Chinle aquifer to the HMC remediation system and the RSE
Report.
Non-concur
Concur, in
part
Non-concur
Non-concur
Non-concur
Additional evaluation is beyond the scope of the study.
The report currently addresses the major shortcomings of
the flushing model, in that it fails to account for the
heterogeneities that would prevent uniform movement of
flushing fluids and would allow mass to remain that will
cause rebound. Additional evaluation is beyond the scope of
the study.
We do not believe this to be necessary to achieve the
objectives of the report.
The report raises the question and we would expect others
to pursue the cause for the questionable water levels in the
Middle Chinle.
Additional evaluation is beyond the scope of the study.
-------
161
162
163
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
4
4
4
The DRSE Report should be revised to provide lifecycle cost,
emission or energy consumption comparisons among long-
term remediation options identified in order to provide for
balanced comparison of long-term costs for the range of
alternatives identified in comparison to the cost, long-term
potential for successful completion of remediation, and
consequences of continuation of the HMC remediation
system as proposed.
The DRSE Report should be revised to provide comparisons
of the effectiveness of the physical barriers -slurry walls and
reactive permeable barriers - that it recommends with the
tailings removal options for long-term remediation of ground
water at the site to meet performance objectives established
in the Uranium Mill Tailings Radiation Control Act. The Act
requires completion of closure and containment without
active monitoring and maintenance as the measure of
tailings reclamation effectiveness.
The DRSE should be revised to eliminate the
recommendation that, "Relocation of the tailings should not
be considered further given the risks to the community and
workers and the greenhouse gas emissions that would be
generated during such work" unless and until a balanced
comparison of the full range of life-cycle costs and benefits,
including considerations of long-term remediation
effectiveness of the range of remedial alternatives, is
incorporated in the Remediation System Evaluation.
Concur
Concur
Non-concur
These analyses have been conducted and will be
incorporated into the draft final report.
See response above.
We stand by our recommendation, even with the additional
analysis and the assessment of the tailing slurry transport
option.
-------
164
BVDA
TASC - GW
(SRIC)
The DRSE Report should be revised to identify and evaluate
both 1) long-term monitoring and maintenance costs and 2)
likelihood of long-term effectiveness of the range of
alternatives identified, including continuation of the current
remediation system and implementation of the alternatives
identified. Alternatives include elimination of the flushing
system, slurry wall, reactive permeable barriers, tailings
removal and any other system with potential for long-term
remediation success. Consideration of long-term remediation
effectiveness and monitoring and maintenance costs should
be incorporated into the RSE contractor team's sustainability
review so that remediation performance as well as energy
consumption and worker safety issues can be considered for
all alternatives.
The sustainability analysis of the various options considers
most of the recommended changes to the pump and treat
system, and the alternative technologies. Additional
evaluation is beyond the scope of the study.
Non-concur,
in part
165
BVDA
TASC - GW
(SRIC)
As tailings removal remains the only conceptual option that
allows for elimination of the source of pollution from the
HMC site, the DRSE Report should be revised to retain
tailings removal as the sole remediation alternative that
provides for the potential to minimize or eliminate the need
for active long-term monitoring and maintenance after
standards are attained.
Non-concur
Moving the tailings moves the location where long-term
monitoring and maintenance will be needed (to the new
repository). Even if the tailings are moved, there will be
monitoring (and probably some ground water control)
required at the Homestake site for some period of time.
166
BVDA
TASC - GW
(SRIC)
The DRSE Report should be revised to identify a range of
spray evaporation rate and technology options in
comparison to the spray evaporation technology in use at
the HMC site.
Non-concur,
in part
The USACE expresses its appreciation to TASC for the
detailed information supplied on the different options of
evaporation technology, systems, and monitoring. It is
outside the scope of the DRSE, however, for the USACE to
perform the study and develop alternatives to the current
spray evaporation system as recommended by TASC. It is
noted that not only evaporative capacity and spread would
need to be considered but also the effect of brine on any
revised system. However, the USACE will include a
recommendation that the current spray evaporation be
evaluated by HMC using the information supplied by TASC
for any optimization improvements.
-------
167
168
169
170
171
172
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
BVDA
TASC - GW
(SRIC)
The DRSE Report should be revised to identify a range of
spray evaporation rate options among the remediation
system modifications it recommends and identify their
implications for pond configuration, acreage and
evaporation performance.
The DRSE Report should be revised to identify the need for,
and scope of, a quantitative evaluation of spray evaporator
performance and effectiveness including evaporative effect,
fallback or sprayed fluids, and distribution of particulates
and radionuclides including radon and radon daughters
passing through the spray system.
The DRSE Report should be revised to identify the scope of
data gathering and system monitoring considerations,
including spray shut-down systems during high winds,
necessary for effective performance of and effective
evaluation of performance of the spray system in the "forced
spray plan" required by DP-725.
The DRSE Report should be revised to identify the
anticipated cost and timeline for completion of remediation.
The DRSE Report should be revised to identify the
opportunity to construct and operate a renewable energy
system at the HMC site as a means to generate income to
offset long-term remediation costs and to provide local
employment.
The DRSE Report should be revised to identify the estimated
length of time that the remediation options identified will be
in place or operated and bases for estimation of the
longevity of those remedial options.
Non-concur
Non-concur
Non-concur
Non-concur
Concur
Non-concur
See above response.
See above response. Also, the report specifically
recommends that the radon gas potentially released from
the evaporations ponds during active spraying be assessed.
As pointed out in the information submitted with these
comments, DP-725 as amended April 12, 2010, contains a
condition that requires HMC to "operate the forced spray
system such that the spray remains within the confines of
the ponds to the extent practicable" and to submit to NMED
a plan detailing sprayer operations. Defer to NMED the
review of the HMC developed plan.
This is beyond the scope of the study.
This will be added to the report, though the analysis will be
limited. Solar power appears to have good potential.
We do not have the tools to project the time to cleanup.
Ground water and contaminant transport modeling may be
necessary. This is beyond the scope of the study.
-------
173
BVDA
TASC - GW
(SRIC)
To provide for stakeholder review of a revised DRSE Report
before it is finalized, it is strongly recommended that EPA
establish a timeline for distribution and RSE stakeholder
review of a revised DRSE Report which includes the
conclusions and recommendations resulting from the revised
evaporation rate calculations and the "sustainability review"
for remediation alternatives.
This has been done.
Concur
This request is outside the scope of the report.
174
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that —
(HMC compile, summarize and report all fenceline
radiological air monitoring data from the 1980s and 1990s.
These data are expected to be stored in hard copies in the
NRC's public document repository.
Non-concur
175
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that —
Any new air monitoring stations be sited consistent with
locations of monitors that had average annual radon
concentrations of less than 0.7 pCi/l-air, which is the upper
range of average levels reported in previous studies.
Concur, in
part
The report currently recommends that HMC consider
additional background monitors at appropriate locations.
The use of historical survey information provides a basis for
determining what those appropriate locations may be. See
also Response to Comment 110.
176
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that —
The planned EPA Region 6 risk assessment include outdoor
and indoor radon monitoring, soil surveys for gamma
radiation and uranium and radium concentrations, surveys
of structures to detect the use of contaminated materials,
and an inventory of natural and human-made sources of
radioactive materials. Monitoring of radon at HMC's
fenceline monitoring stations should be done concurrently
with air monitoring in the residential areas.
Defer to EPA Region 6. The RSE team provided some input
into the scope of the EPA risk assessment, however, the EPA
assessment is part of a larger regional effort.
Non-concur
177
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that —
EPA-6 consider hiring a community member to serve as a
liaison between the community and EPA and its contractors
during field studies associated with the assessment and at
the time results of the risk assessment are presented to the
community.
Defer to EPA Region 6.
Noted
-------
178
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that —
EPA Region 6 review and reconsider the findings, conclusions
and recommendations of the 1989 Record of Decision of the
Radon Operable Unit in light of the findings of new
environmental monitoring conducted as part of the planned
risk assessment and by HMC under its routine and expanded
monitoring program.
Noted
Defer to EPA Region 6.
179
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that —
HMC comply with NRC Regulatory Guide 4.14 and
immediately begin monitoring Pb-210 in particulates
measured at its eight air monitoring stations.
Concur, in
part
The report identifies this discrepancy from the NRC guidance
and recommends that the basis for not including Pb-210 be
discussed in the SAEMR.
180
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that —
HMC establish at least one air monitoring station in the
residential area southwest of the site, including consultation
with BVDA, EPA and NRC before selecting a suitable
residential monitoring location. Consideration should be
given to establishing more than one air monitoring station in
the residential area to provide an appropriate geographic
distribution that takes into account local wind speeds and
directions, and possible contributions to radiation releases
from HMC's two irrigation plots located west of Valle Verde
Estates.
Concur, in
part
The report currently recommends that 2 to 3 additional
radon monitors be located between the current monitoring
stations near the residential areas. Given the magnitude of
the calculated doses from particulate radiation sampling at
the site boundary locations, HMC #4 and #5, there does not
appear to be significant need to require HMC to place full air
monitoring stations at greater distances from the site.
181
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that —
HMC compile and report all previous meteorological data,
and commit to including all future meteorological data in its
Semi-annual Environmental Monitoring Reports. The DRSE
Report should further recommend that HMC undertake a
study of localized wind patterns to determine if the tailings
piles or other land features contribute to a channeling of
currents into the
adjacent community.
Concur, in
part
The report currently recommends that wind direction data
from the on-site meteorological station be collected during
each monitoring period and presented in the SAEMR. HMC
included a wind rose for the period of September 2008 to
August 2009 in the 2009 Annual Irrigation Evaluation report.
The report will be revised to clearly recommend that the
wind rose data be included with the air sampling results in
the SAEMR.
-------
182
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that —
HMC establish a meteorological station in the residential
area. The residential air monitoring station recommended in
Section S.l(vii) above could be co-located at a new
residential meteorological station. The residential
meteorological station should be capable of
measuring wind speeds and directions and ambient
temperature and pressure.
The location of the current meteorological station near the
source of the contaminants on the southern side of the LTP
should be adequate.
Non-concur
183
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that —
Homestake conduct and submit to NMED, NRC and EPA
radiochemical analyses of precipitates deposited by the
sprayers on the berms of the evaporation ponds as soon as
possible.
Non-concur
The EP area is part an active remediation system on a
licensed site. Upon completion of remedial action, all surface
soils not covered under the final radon barrier will be
required to meet the cleanup criteria identified in 10 CFR 40,
Appendix A, Criterion 6(6).
184
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that —
Data on particulates detected at the seven perimeter air
monitors be analyzed to determine if radionuclide levels are
correlated with wind patterns (velocities and directions)
and/or spraying events.
Non-concur
The weekly air sample filters are composited and analyzed
on a quarterly basis. This integration averages out the
numerous spraying events and variations in wind direction
making correlation impractical. It is more appropriate to use
the historical wind patterns as the basis for locating the air
monitors.
185
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that — DP-
725 and SUA-1471 be amended to prohibit spraying when
weather conditions would cause mists and precipitates to be
deposited outside of the perimeters of the ponds.
Non-concur
As pointed out in the information submitted with these
comments, DP-725 as amended April 12, 2010, contains a
condition that requires HMC to "operate the forced spray
system such that the spray remains within the confines of
the ponds to the extent practicable" and to submit to NMED
a plan detailing sprayer operations. Defer to NMED the
review of the HMC developed plan.
186
BVDA
TASC - Air
(SRIC)
The DRSE Report should be revised to recommend that — An
assessment be conducted on whether existing monitoring
data are adequate to determine if effluent spraying is
protective of public health. If the RSE Team finds that
existing monitoring data are not adequate to determine if
effluent spraying is protective of pubic health, the final
report should identify the scope of a data-gathering program
needed to make such a
determination.
Concur, in
part
The report already recommends that the potential for radon
to be released during active spraying be assessed and
recommends additional radon monitoring in the direction of
preferential radon flow. The results of that assessment are
deferred to the agencies.
-------
187
BVDA
TASC - Air
(SRIC)
The DRSE Report should recommend that HMC reassess all
input parameters to the calculation of the Total Effective
Dose Equivalent (TEDE), including and
especially the occupancy factor and the radon-radon
daughter equilibrium factor.
Concur, in
part
The report specifically recommends that HMC confirm the
assumption of the radon/radon progeny equilibrium factor.
The report also cites NRC guidance regarding the appropriate
use of occupancy factors. The report will specifically
recommend that the assumptions for the occupancy factor
be confirmed.
188
BVDA
TASC - Air
(SRIC)
The DRSE Report should further recommend that the NRC
staff review all assumptions and rationales
presented by HMC in the annual TEDE calculation provided
in the semi-annual environmental
monitoring reports.
Concur, in
part
The report recommends revisions to the HMC air monitoring
program and the confirmation of assumptions used in the
TEDE calculations submitted to demonstrate compliance
with NRC requirements. See Responses to Comments 110 &
114 that encourages NRC staff to work with HMC.
189
BVDA
TASC - Air
(SRIC)
The DRSE Report should review the public health risks
associated with chronic exposure to levels of radon observed
in the community. The planned EPA risk
assessment should include a summary of historic and current
radon levels around the HMC site and in the community, and
calculate doses and respiratory risks using those data. All
management alternatives to mitigate or eliminate exposures
from anthropogenic sources of radiation, heavy metals and
other contaminants should be fully and fairly considered.
Outside of the scope of the focused review. Defer to the EPA
human health risk assessment.
Non-concur
190
BVDA
TASC - Air
(SRIC)
The DRSE Report should recommend that HMC, EPA, NRC
and NMED identify funding for health studies in the
communities, and work with BVDA to identify uninvolved
third-party organizations with appropriate credentials to
design and implement health studies in the affected
community. The RSE Advisory Committee, which includes
BVDA members, may be an appropriate vehicle in which to
begin these discussions to ensure that all stakeholders have
a part in identifying funding sources and recommending
health study providers.
Defer to the agencies.
Non-concur
-------
191
192
BVDA
TASC-
Addenda
(SRIC)
BVDA
TASC-
Addenda
(SRIC)
General
General
When read in tandem, the two addenda and the DRSE
Report identify many unresolved issues regarding both the
effectiveness of the current ground water remediation
program and the long-term management of a fully
remediated site. To resolve the difficult issues related to
current performance and long-term management, the RSE
Team should identify the full range of options in both areas
and the range of additional actions and investigations to
define an optimized path forward for remediation at the
HMC site. By treating these portions of the remediation
system optimization separately, the tailings relocation option
(or options, given there are several options that have not
been considered by the RSE Team, as outlined below) is
dismissed prematurely prior to demonstration of an effective
ground water remediation system and without the level of
scientific evaluation merited by the complex and challenging
conditions and the 50-year history of ground water
contamination at the HMC site.
To provide for more thorough consideration of remediation
and long-term management options at the HMC site, the RSE
Team should evaluate whether the existing EPA -Nuclear
Regulatory Commission (NRC) Memorandum of
Understanding (MOU) provides an effective mechanism for
implementing remediation optimization. This MOU
apparently supplanted the need for a Remedial
Investigation/Feasibility Study (RI/FS) under authority of the
Comprehensive Environmental Response, Compensation,
and Liability Act (CERCLA) for the "ground-water operable
unit" in the mid-1980s. Absent an RI/FS, the MOU
mechanism should be reviewed to ensure that all feasible
options for improving and expediting ground water
remediation in the short term and long-term site
management and rehabilitation are considered.
Non-concur
Non-concur
The analyses that have been performed are consistent with
or even beyond what is typically done for an RSE. These
analyses are consistent with the scope of work for the study.
We disagree that the relocation of the tailings was
"dismissed prematurely"
This is beyond the scope of the study.
-------
193
BVDA
TASC-
Addenda
(SRIC)
General
When considered together, the contents of the addenda and
the DRSE report would have major implications for the scope
and form of the HMC site's remediation system if they were
considered at the level of detail appropriate for review of
alternatives for the "Corrective Action Plan" (CAP) under
review by the NRC since 2006. If the DRSE Report was
considered as a set of substantive comments on the
proposed CAP license amendment currently under review by
the NRC, or on the DP-200 application currently under
review by the New Mexico Environment Department
(NMED), implications of its suggestions and
recommendations regarding regulatory actions affecting the
site could be
thoroughly considered.
Noted
We defer to the agencies.
-------
194
195
196
BVDA
TASC-
Addenda
(SRIC)
BVDA
TASC-
Addenda
(SRIC)
BVDA
TASC-
Addenda
(SRIC)
General
Evap.
Evap.
Since the remediation system evaluation or optimization
process under CERCLA is a science-based initiative based on
sound technical approaches, and not a regulatory-based
process, serious consideration of alternatives for the long-
term remediation of the site and the area's ground water
must be completed in the
context of the existing NRC license, NMED's ground water
discharge permit, or both concurrently. For these reasons,
the RSE Team should specify in the final RSE Report that the
identified optimization opportunities should be subject to a
full-scale analysis as corrective action options, including
consideration of all options for tailings removal and
relocation. In addition, the RSE Team should specify that this
analysis should be conducted under authority of the Atomic
Energy Act and the National Environmental Policy Act at the
federal level and the New Mexico Water Quality Act at the
state level. It is suggested that the optimization
enhancements identified by the RSE Team be considered as
modifications to the Homestake CAP currently being
reviewed by the NRC as a license amendment. If this is done,
the RSE Report could provide a basis for a "new, hard look"
as it provides substantial new information not available
during the review of previous license amendments.
The RSE Team should suggest a detailed review of the full
range of long-term management options, including both on-
site containment and off-site disposal, in the context of
remediation system optimization.
Conducting a pilot test, if needed, before incorporation of
the two identified treatment system enhancements, as
proposed by the RSE Team, should be incorporated into
existing performance requirements for the NRC license and
the DP-200 NMED ground water discharge permit to
supplement and/or optimize the site's Corrective Action
Plan.
Non-concur
Noted
Noted
The determination of the nature, scope, and timing of any
future analysis of alternatives would be conducted by the
agencies.
See comment above.
We defer to the agencies.
-------
197
BVDA
TASC-
Addenda
(SRIC)
Evap.
The "Combination of Evaporation Capacity" analysis does
include significantly expanding the capacity of the RO
treatment system as a remediation system
optimization option. The RSE Team should assess whether
the RO plant capacity could be raised to take full advantage
of all evaporation pond capacity on site. If the evaporations
ponds can evaporate additional flow, the RSE team should
evaluate combinations that include expanded RO treatment
capacity. Expanded RO treatment capacity could allow for
increased extraction of fluids containing contaminants of
concern, particularly if the current system is revised to
reduce the treatment burden associated with flushing flows
derived from both injection and extraction.
The report does recommend measures to increase the plant
throughput up to 600 gpm with allowances for maintenance.
Analysis of the options of increased treatment and
evaporation pond configurations will be added to the report.
Concur
198
BVDA
TASC-
Addenda
(SRIC)
Evap.
The discussion of evaporative capacity and treatment
options should include a discussion of the disposition of
contaminants of concern that are managed by those
systems, since they are the focus of the remediation effort.
The RSE Team should suggest that the remediation system
include identification of the distribution of radionuclides,
metals and gross constituents in fluids and sludges that are
stored in the four existing ponds and in precipitates
deposited on and around the berms of the ponds.
Non-concur
There is sampling of the brine in the ponds, from what we
understand, but the sampling of the solids raises many
issues, including the potential to harm the liner during
sampling, and the variability of concentrations in the solids
laterally and vertically in the ponds. The variability would
likely make characterization of the contents difficult. The
measurement of the influent and effluent concentrations
actually is the best way to determine the composition of
materials that is going/has gone into the ponds.
199
BVDA
TASC-
Addenda
(SRIC)
Evap.
Since Homestake has stated previously that 98.6 percent of
radon emitted from the facility is from the LTP and Small
Tailings Pile (STP), covering the top of the LTP with a final
radon cover could substantially reduce radon emissions and
resulting radiation exposures to local residents. The final RSE
should suggest that once flushing is terminated, Homestake
proceed expeditiously to cover the top of the LTP. (Installing
the final radon cap would not preclude relocating the tailings
if that option is implemented as discussed below.)
Non-concur
The regulations, 10 CFR 40, Appendix A, Criterion 6(3) and
the HMC license requires that the radon flux from the piles
not exceed the final radon flux standard of 20 pCi/m2s during
phased emplacement of the final radon cover. The HMC
license (Condition 37.F.) also requires that the final radon
barrier not be placed until it is demonstrated that 90% of the
expected settlement of the pile has occurred.
-------
200
BVDA
TASC-
Addenda
(SRIC)
Carbon
The Carbon Footprint Addendum dismisses the tailings
removal option based only on costs and carbon emissions,
with no consideration of the long-term environmental
performance goals for the site. This narrow "energy cost
only" view fails to consider long-term objectives for the HMC
site — ground water remediation and reduction of potential
health risks for nearby residents. The addendum appears to
provide only a comparison of energy budgets for three
environmental management options at the site, one of which
is continuing the current remediation system, with all of its
previously identified shortcomings.
Non-concur
Even with tailings (and some underlying soil) removal, some
ground water control would likely be necessary for some
time due to contamination that has been released into the
saturated site soils. Certainly, there would be some decrease
in risks to the nearby residents. We do not dispute that, but
note that there is some risk of exposure being transferred to
another location.
201
BVDA
TASC-
Addenda
(SRIC)
Carbon
The Carbon Footprint Addendum should be incorporated
into a section of the final RSE Report related to long-term
environmental management. The RSE Team should
encourage retention and refinement of the tailings
relocation option for analysis beyond its brief and
incomplete consideration in the addendum.
The carbon footprint addendum will be incorporated into the
report.
Concur, in
part
202
BVDA
TASC-
Addenda
(SRIC)
Carbon
In the Carbon Footprint Addendum, the RSE Team offers a
comparison of alternatives that are not evaluated using
comparable types of information. The alternatives are: (1)
the current system; (2) tailings and subsoil excavation and off-
site disposal; and (3) slurry wall construction. The addendum
attempts to compare and contrast information drawn from
the fully engineered and permitted tailings relocation
program for the Moab, Utah, tailings with few site-specific
considerations and the sparsest of conceptual models for the
"current system" and "slurry wall" remediation options.
The analyses that have been performed are consistent with
or even beyond what is typically done for an RSE. These
analyses are consistent with the scope of work for the study.
Noted
-------
203
BVDA
TASC-
Addenda
(SRIC)
Carbon
The "current system" as conceptualized by the RSE Team
would appear to be different from the "current system
including flushing," which the RSE Team projects will not
meet the goal of attaining NRC-approved "action levels" for
uranium and other contaminants in the alluvial aquifer by
2017. It should also be noted that the "current system"
includes the use of spraying to enhance evaporation rates, a
practice to which the local community has repeatedly
objected, based not only on potential spray impacts on air
and land quality and radiation exposures, but also on their
repeated observations of sprays and spray particulates
drifting into the adjacent communities.
Noted
The pump and treat system assessed in the analysis is
essentially the current system for purposes of assessing
sustainability. The analysis does include pumps used for the
sprayers. This is conservative if the total energy use and
carbon emissions from the pump and treat alternative is
being compared to the removal of tailings and other options
(it would make the alternatives look better relative to the
pump and treat system).
204
BVDA
TASC-
Addenda
(SRIC)
Carbon
The conceptual model for the single "new technology"
option, the slurry wall alternative, may prove valuable, but
there is no performance record applicable to the HMC site or
a site of analogous proportions and conditions. The RSE
Team should examine the slurry wall system installed at the
IMC Fertilizer, Inc., Gypsum Stack Expansion in Polk County,
Florida (see: http://www.ardaman.com/award2.htm). This
system,
which includes 20,000 linear feet of vertical cutoff walls up to
110 feet deep, is less than 20 years old and is the only
example of currently implemented slurry wall technology
that could be identified online. Notably, the Carbon
Footprint Addendum does not use the IMC slurry wall system
or any other real world example of a slurry wall system, as a
model for comparison and contrast with facilities and
hydrologic conditions at the HMC site.
The tool used to compute the sustainability metrics allows
only some site-specific input. We agree such a slurry wall is
feasible.
Concur, in
part
205
BVDA
TASC-
Addenda
(SRIC)
Carbon
The RSE Report should suggest that EPA, HMC, NRC or NMED
gather data on the full cost of perpetual pump-and-treat
systems with and without slurry walls. This approach would
provide for a full-scale comparison of costs and benefits with
the site-specific tailings removal option before that option is
eliminated.
We defer to the agencies to determine whether additional
study of the alternatives are warranted.
Non-concur
-------
206
207
BVDA
TASC-
Addenda
(SRIC)
BVDA
TASC-
Addenda
(SRIC)
Carbon
Carbon
A significant portion of the energy and safety costs
associated with the tailings relocation option is associated
with the transport of tailings and subsoil to an alternative
site outside of the San Mateo Creek floodplain. Identification
of a site, or sites, closer to the existing tailings facility and
thorough consideration of transportation alternatives (e.g., a
slurry pipeline with wastewater recycling, conveyor-belt
systems, or rail transport) may allow costs identified for the
tailings relocation scenario to be significantly reduced.
Truck driver and equipment operator jobs are of
fundamental importance to communities with a history of
mining activity. Both are associated with safety risk, based on
miles logged on the equipment. Employment opportunities
offered by tailings removal may represent the largest
number of local jobs available in the uranium industry for
many years unless and until a new uranium mill is
constructed to process ore from the hard rock uranium mine
proposals in the Mt. Taylor area. As a point of comparison,
the potential employment opportunities associated with
tailings relocation should be recognized for the substantial
personal, corporate and governmental income it could
generate, and for its potential to add value to the local
economy by removing a contaminant source from a
floodplain upstream of a growing community. As it now
stands in both the DRSE Report and the addenda, the
relocation option is viewed only as a set of safety risks and
carbon emissions, with no other attributes.
Concur
Concur
The slurry option was evaluated and will be described in the
report.
We will mention the economic impacts of such a project in
the report.
-------
208
BVDA
TASC-
Addenda
(SRIC)
Carbon
The RSE team offers a set of important but arbitrary
assumptions that are heavily weighted in favor of the
unproven pump-and-treat and slurry wall remedies. Those
assumptions allow for a 75-88 percent reduction in
additional pump-and treat technology and operating costs
for a slurry wall over a 50-75 year period, but do not indicate
whether applicable standards will have been met or pre-
existing ground-water quality restored through the use of
these remediation methodologies. The failure to consider full-
scale, long-term management costs for the "current system"
and slurry wall alternatives compared with tailings relocation
gives those options an unwarranted advantage that is not
supported by the performance of those technologies.
The ground water extraction and treatment system can be
effective in preventing migration and reducing the footprint
of dilute plumes. We would not characterize it as
unproven."
Non-concur
209
BVDA
TASC-
Addenda
(SRIC)
Carbon
The assumptions of the Carbon Footprint Addendum should
be modified to extend the active life of the HMC site's
proposed pump-and-treat system and slurry walls to a
reasonably long period, specifically "up to 1,000 years, to the
extent reasonably achievable, and, in any case, no less than
200 years," as required in 10 CFR 40, Appendix A, Criterion
6(l)(i), the long-term performance standard set out to
comply with the Uranium Mill Tailings Radiation Control Act
of 1978, which the U.S. Department of Energy (DOE) must
apply to the HMC site if and when current site remediation
standards are attained and the site is deeded to DOE.
The carbon footprint for the pump-and-treat system is easily
scaled if a longer time frame would be considered. Note,
though, that the scope of the system will probably decrease
overtime.
Non-concur
-------
210
BVDA
TASC-
Addenda
(SRIC)
Carbon
The current remedial system at the HMC site has not been
shown to be effective enough to meet projected
performance milestones identified by HMC and regulatory
agencies, even after more than 30 years of active
remediation conducted by a site owner with the capacity to
modify pumping, active evaporation and treatment activities.
No slurry wall examples are referred to by the RSE Team to
support a major drop-off in slurry wall costs over a 50-75
year period, much less characterization of the effectiveness
of a slurry wall to meet environmental standards.
Non-concur
Our analysis only considered the impact of slurry wall
construction. There is little operation and maintenance for a
slurry wall. There are a number of slurry walls that have
been constructed for environmental purposes, and when
properly constructed, they function well over extended
periods of time. Maintenance is generally to assure there
are no extreme head differences across the wall.
211
BVDA
TASC-
Addenda
(SRIC)
Carbon
The DRSE Report attributes a long-term lack of success to the
site's current remediation system, notably the flushing
program that the RSE Team recommends for discontinuance,
when compared with attainment of ground water
remediation goals. No effort is made in the Carbon Footprint
Addendum or other portions of the DRSE Report to
demonstrate any longterm performance attributes of a slurry
wall system.
See response above.
Non-concur
-------
212
213
BVDA
TASC-
Addenda
(SRIC)
BVDA
TASC-
Addenda
(SRIC)
Carbon
Carbon
The lack of success in attaining remediation, including NRC-
authorized "action levels," is reflected in the Concentration
Trends spreadsheet posted to the RSE website by the RSE
Team on March 18, 2010, and discussed, in part, in the
previous TASC report, "Observations and Recommendations
Regarding the Draft Focused Review of Specific Remediation
Issues for the Homestake Mining Company (Grants)
Superfund Site, February 2010 - Ground Water
Considerations, May 6, 2010." The concentration trends
compiled by the RSE Team from HMC site data show little, if
any, reduction in uranium concentrations across large
portions of the site, including (as identified on the tabs of the
Concentration Trends Spreadsheet) the west, north and
south sumps, the NW, NE, SE and SW tails, and wells S2 AND
B4. Those locations are areas not affected by the dilution
"plumes" associated with the injection well systems, which
so heavily influence Monitoring Well X, as discussed in the
May 6, 2010 comments on ground water aspects of the DRSE
Report.
If the RSE Team recognizes the lack of demonstrated long-
term success with the current remedial system and the lack
of any demonstration of slurry wall performance over the
long-term, then the tailings relocation option remains the
only remedy that can attain clean-up standards at the site,
much less attain cleanup standards without long-term active
monitoring and maintenance. The tailings relocation option
is the only option that offers the possibility of a final remedy
for decontaminating ground water by removing the source of
the pollution — the unlined tailings piles. The current system
and slurry wall options are essentially treatment methods
that would operate in perpetuity.
Concur
Non-concur
Additional discussions regarding some of the trend plots for
the sumps and drains has been added to the report.
We do not necessarily believe the pump and treat system
would have to run in perpetuity. We can not estimate the
true duration.
-------
214
215
216
217
BVDA
TASC-
Addenda
(SRIC)
BVDA
TASC-
Addenda
(SRIC)
BVDA
TASC-
Addenda
(SRIC)
BVDA
TASC-
Addenda
(SRIC)
Carbon
Carbon
Carbon
Carbon
Some of the long-term environmental management bonds
for New Mexico facilities include replacement of pumping
systems for perpetual pump-and-treat programs, such as at
the Chevron-Questa molybdenum operations. Similar
perpetual treatment costs can be expected if some variation
on the current remedial system or the slurry wall system is
eventually used instead of the tailings relocation option.
Retention of the tailings relocation option will allow for cost
and performance estimates for that option to be optimized
and will allow for consideration of appropriately long-term
(hundreds to thousands of years) costs and performance
estimates for the other two environmental management
scenarios, the current system and slurry walls, to be assessed
at a detailed level incorporating conditions in and around the
HMCsite.
A new site for permanent disposal of the tailings would have
to meet current NRC and NMED standards, including below-
grade disposal in multi-barrier trenches, placed in a
geotechnically suitable location removed from human
settlements (see 10 CFR 40, Appendix A, Criteria 1, 3, 5 and
6, among others). Accordingly, the tailings relocation option
should remain as a primary option for long-term
management of HMC site tailings, unless and until an
effective remedy is demonstrated.
Funding the life-cycle cost of remediation at the HMC site
has been and will continue to be a significant public cost.
Accordingly, consideration should be given to use of the site
for renewable energy generation to offset carbon costs and
fund remediation and local employment.
Noted
Non-concur
Noted
Concur
Note that the relocated tailings would also require care for
hundreds of thousands of years.
We defer to the agencies.
A brief analysis of alternative energy options at the site has
been added. We would hope that some future use of the
site will include alternative energy generation, particularly
solar.
-------
218
219
220
221
BVDA
TASC-
Addenda
(SRIC)
BVDA
TASC-
Addenda
(SRIC)
BVDA
TASC-
Addenda
(SRIC)
BVDA
TASC-
Addenda
(SRIC)
Regional
GW
Regional
GW
Regional
GW
Regional
GW
The two RSE Report addenda continue to emphasize short-
term (50-year or less) conditions in San Mateo Creek,
including the HMC site, rather than longer-term(100-year
and beyond) flow conditions in which historic flows may be
restored. The HMC site does not exist in isolation from the
historical surface and groundwater flow patterns of the
watershed around it.
The historic flows in San Mateo Creek, including, but not
limited to, flows from proposed uranium mine dewatering
projects (see the Roca Honda Mine
application:
http://www.emnrd.state.nm.us/MMD/MARP/permits/MK02
5RN.htm; click on "Mine Operations Plan") will provide a
perpetual source of upstream flow, both
surface and subsurface, into the HMC site without requiring
an extensive, perpetually-endowed pumping effort.
The historic flows of Bluewater Creek, retained by the rapidly
aging Bluewater Dam in the Zuni Mountains, are likely to
return to the Bluewater Valley eventually and also provide a
perpetual source of upstream flow.
Management of environmental management activities on
site continues to assume that the small and large tailings
piles in the floodplain of San Mateo Creek near its
confluence with Bluewater Creek will continue to be
permitted and maintainable as permanent disposal sites.
These piles are not lined, will take many more years to dry
out before they cease to be sources of fluid infiltration to the
alluvium and underlying Chinle bedrock, and, in the case of
the Small Tailings Pile, will be the final disposal location for
solid wastes associated with the current remediation system.
Noted
Noted
Noted
Noted
We agree the site needs to be considered in a regional
context. We have attempted to consider upgradient and
downgradient conditions that affect the interpretation of site
conditions, but a full regional analysis was beyond the scope
for this study.
See response above.
This is beyond the scope of the study.
This is beyond the scope of the study.
-------
222
223
224
225
BVDA
TASC-
Addenda
(SRIC)
BVDA-
Addenda
(Head-Dylla)
BVDA-
Addenda
(Head-Dylla)
BVDA-
Addenda
(Head-Dylla)
Regional
GW
Management of the thousands of acre-feet per year of water
that flow through the area affected by the HMC site tailings
continues to evolve. The RSE Team should consider much
longer-term conditions than the 50-year life of HMC in the
Bluewater Valley. The RSE Team, and applicable regulatory
programs, should aim to restore natural ground water and
surface water flow conditions without active maintenance as
the appropriate environmental conditions if and when
standards are attained in areas affected by HMC operations.
Final conditions should not rely on deed restrictions and
temporary provision of alternative water supplies.
The Large Tailings Pile restricts a major flood plain. It is
unlined and will leak contaminants in perpetuity.
The Large Tailings Pile as well as the other tailings pile and
waste from current evaporation ponds must be removed to a
safe, permanent storage site. No other alternative provides
a full remedy, protective of future generations. We hereby
request the EPA to extend the USACE's scope of work to
include a serious and full consideration of removal and long-
term storage of the tailings piles and contamination wastes.
If Homestake/Barrick's expert is correct and most of our
radon exposure comes from the tailings piles and not the
ponds, the tailings piles need interim cover to reduce radon
exposure to our community until they are removed.
Noted
Noted
Noted
Noted
This is beyond the scope of the study.
The severity of the leakage will vary over time.
We defer to the agencies to determine whether additional
study of the alternatives are warranted.
The report includes recommendations to increase radon
monitoring locations and to confirm assumptions used in the
radon flux measurements and radon dose calculations for
comparison to the regulatory limits. HMC has increased the
interim cover thickness on the LTP twice to address high
radon flux measurements.
-------
226
227
228
229
230
BVDA-
Addenda
(Head-Dylla)
BVDA-
Addenda
(Head-Dylla)
BVDA-
Addenda
(Head-Dylla)
BVDA-
Addenda
(Head-Dylla)
NMED-
Addenda
Evap.
Clearly, Homestake/Barrick Gold must increase RO capacity
to enable a full cleanup of contaminated groundwater. The
RO process must be adequate to eliminate the need for
spraying, which BVDA continues to oppose because it
exposes the community to radon and has never been
confined to pond berms as aerial photos and community
experience confirm.
BVDA assumes and expects that the optimization identified
by the RSE process will become the basis of a more complete
review of Homestake/Barrick Gold's Corrective Action Plan
by the NRC under the Atomic Energy Act and the National
Environmental Policy Act and that the NMED will use it in
future Discharge Plans under the NMWQA.
Time is of the essence. Our community has suffered long
enough and it is no longer sufficient for the NRC to simply
allow another five years for cleanup. This has been the
policy for too long and has allowed Homestake/Barrick Gold
to evade their responsibility with inefficiency and delays.
New cleanup goals are needed and Homestake/Barrick Gold
must commit the resources to solve this contamination
problem.
BVDA hopes and expects there will be further opportunity to
comment on the RSE report before it is finalized and made
public. BVDA looks forward to learning soon how the
Nuclear Regulatory Commission and Homestake/Barrick Gold
plan to implement RSE recommendations once the report is
finalized.
Elements of the "proposed pumping scenario" should be
briefly summarized in this appendix for additional clarity to
the reader. From Section 4.1 of the RSE, NMED understands
that the primary element of this scenario is discontinuation
of current flushing for the Large Tailings Pile.
Concur
Noted
Noted
Concur
Concur
The report addresses options for expansion of capacity.
We defer to the agencies to determine whether additional
study of the alternatives are warranted.
The draft final document will be made available to all
members for review.
This will be clarified in the appendix.
-------
231
NMED-
Addenda
Evap.
The projected effluent rate of the toe/tailings drain
collection system (65 gpm [Table 5]) under the proposed
pumping scenario inexplicably is indicated to be higher than
that of the current pumping scenario (61 gpm [Table 4]).
Although the rate under the proposed pumping scenario
might equal that of the current pumping scenario
temporarily, the RSE states that the rate from this source
should decrease significantly with time (Section 4.1, p. 19).
Therefore the analysis presented in Tables 2 through 7
should be reviewed and modified accordingly to account for
this projected decline.
The assumption was that the current flow would continue
for some time and decline. The current flow would
represent "worst case" conditions for assessing evaporation
capacity.
Noted
232
NMED-
Addenda
Evap.
The Corps of Engineers' RSE team should consider including
an analysis of possible modified evaporation rates or influent
rates under implementation of possible modifications
suggested in section 5.3, and the consequent effects on the
necessary evaporation capacity.
Non-concur
The decreases in evaporative loading would need to be
determined through either the actual pretreatment pilot or
more detailed design of the addition of a high performance
column. This is beyond the scope of the RSE to perform.
233
NMED-
Addenda
4.4.4
Implementation of a slurry wall, as included in Table 4,
would necessitate continuation of ground
water extraction in perpetuity; is unclear what time period is
modeled in the calculation that is
presented in Table 4.
The conditions assumed/modeled are based on recent
concentrations and estimated flows.
Noted
-------
Homestake Mining Company's Response to
Recommendations Contained in the U.S. Army Corps of Engineers'
Focused Review of Specific Remediation Issues:
An Addendum to the Remediation System Evaluation for the Homestake Mining
Company (Grants) Superfund Site, New Mexico (Draft Report, February 2010)
May 7, 2010
Homestake Mining Company (HMC) has prepared the enclosed responses to the
recommendations contained in the U.S. Army Corps of Engineers' (ACOE) evaluation of the
remediation system at the Grants, New Mexico Superfund Site. Several recommendations are
provided relative to the extraction and injection system, groundwater characterization,
monitoring program, and water treatment. A summary of the recommendations is presented in
the Executive Summary of the ACOE Draft Focused Review of Specific Remediation Issues, An
Addendum to the Remediation System Evaluation (RSE) Report, and each recommendation is
presented below followed by HMC's response to the recommendation. Our responses focus on
the recommendations made by the ACOE and we have not attempted to address every issue.
HMC has identified inconsistencies or incorrect statements in our review of the Draft RSE
Report and each is discussed at the end of this document in Attachment A.
The Grants site is recognized as a complex site with multiple regulatory agency oversight. Prior
reviews note that "[t]he Site is well maintained and remedial actions performed at the Site have
reduced contaminant levels on-site as well as plume size reduction and containment."1 Further,
that "[t]he groundwater collection and injection system appears to contain the contaminated
groundwater and has been effective in reducing groundwater contaminant concentrations within
the impacted aquifers."2
As previously determined in the December 2008 Draft RSE Report, there is no indication that
HMC's overall remediation strategy and the current regulatory agencies is deficient in protecting
human health and the environment. This fact is further substantiated by the Agency for Toxic
Substances and Disease Registry's Health Consultation report, which "categorized the
groundwater in the private wells not connected to the Milan water supply as a no apparent public
Second Five-Year Review Report for Homestake Mining Company Superfund Site, Cibola County, New Mexico,
AVM Environmental Services, Inc. and U.S. Army Corps of Engineers, Albuquerque District, August 2006.
2 Id.
May?, 2010 Homestake Mining Company Page 1
-------
health hazard."3 Further, the December 2008 Draft RSE Report acknowledged the groundwater
flow regime is understood and containment of the contaminant plume has been achieved through
implementation of a hydraulic barrier downgradient of the Grants site tailings piles, and there is
no contribution of contaminants from the tailings piles to offsite groundwater. The current Draft
RSE Report also notes that "the current remediation systems have been making significant
progress in improving groundwater quality at the site. . . ."
With this background in mind, HMC submits that the current evaluation fails in its mission to
provide concrete recommendations to enhance the remediation system at the Grants site. HMC
understood the purpose of this review was to suggest other approaches or technology initiatives
that could be incorporated in conjunction with HMC's current remediation system to increase
efficiency in achieving site closure goals at the site. The ACOE evaluation does not accomplish
this purpose. HMC is actively and aggressively remediating the site with "significant progress."
The ACOE evaluation offers little in the way of aggressive remediation, and in fact suggests less
active approaches (i.e., less flushing of the large tailings pile). The recommendations contained
in the evaluation are often inconsistent and reflect a misunderstanding of the site's closure goals.
HMC's comments and suggestions to the ACOE evaluation outline some of the areas where
HMC does find agreement with recommendations in the Draft RSE Report and in those cases it
presents our plan for addressing those recommendations.
HMC has identified a number of areas where disagreement exists in the conclusions and
recommendations; wherever possible, we have provided a rationale for our disagreement and
have included salient information that supports our position or perspective on the particular
issue. In a number of areas, HMC finds that a thorough technical understanding of the issue
leads to a different conclusion or recommendation than what is outlined in the Draft RSE Report.
As a paramount example, the recommendation that flushing of the large tailings pile should be
"discontinued" or "curtailed", at a minimum, is reflective of a lack of understanding of the
hydraulics and geotechnical and geochemical mechanisms that are in play within the tailings
pile. As established by the geochemical modeling, the soluble portion of the uranium in the
tailings pile has been or will be collected, while the insoluble portion of the uranium will remain
immobile. As such, we strongly disagree with the conclusions and recommendations,
particularly in light of the fact that the flushing program is advancing to the latter stages of that
program activity (and is demonstrating success) as part of the overall remediation strategy at the
Grants site.
Another example of significant disagreement, and there are others that are detailed in the
following text of HMC's comments, is the suggestion that ion exchange is an effective
Agency for Toxic Substances and Disease Registry, "Health Consultation, Homestake Mining Company Mill Site,
Milan, Cibola County, New Mexico," June 26, 2009.
May?, 2010 Homestake Mining Company Page 2
-------
alternative to treat collected groundwater being applied in those areas where HMC is currently
using land application/crop irrigation. HMC stresses that the need to move significant volumes of
water is absolutely necessary to advance restoration efforts. The option suggested by ACOE has
been evaluated, and the conclusion has been that a prohibitive degree of pre-treatment is
necessary to deal with the inherent water chemistry that is evident in much of the groundwater in
the area of the Grants site — irrespective of whether the groundwater has been impacted by the
existence of the Grants tailings piles since the 1950s. Addressing this issue, and operation of the
ion exchange system itself, carries with it the need to manage waste streams from the process.
Recent experience has shown that management of remediation process waste streams in storage
ponds (or expansion thereof) at the Grants site is problematic at best.
The ACOE evaluation is overreaching in reviewing areas that do not pose any risk at the site.
The evaluation fails to consider the U.S Environmental Protection Agency's (EPA) prior
findings that the operating HMC mill and tailings embankments "are not contributing
significantly to off-site subdivision radon concentrations."4 It is difficult to understand why
ACOE is raising radon issues when the site is no longer operating, when these issues were found
to pose no risk during operations and before partial cover of the tailings pile was put in place.
Further, events such as the New Mexico Environment Department's approval of HMC's DP-725
discharge permit has addressed issues concerning the site's evaporation pond system emissions
and are no longer at issue.
The ACOE evaluation also raises issues in areas in which HMC is operating beyond its license
and permit requirements. Concerns over HMC's current level of monitoring are misplaced.
Approximately 80 wells are required to be monitored under current license and permits, yet
HMC voluntarily monitors a significant number of other wells to access performance of the
remediation system and to continually characterize the extent of on-site and off-site impacts to
groundwater. HMC's efforts are incorrectly characterized as redundant and not clearly tied to
objectives. Like several areas of the ACOE evaluation, HMC fails to understand how such
recommendations will enhance the remediation of the Grants site.
The Scope of Work (SOW) for the "second phase" of the RSE that was to govern the task
elements of the report draft under current consideration was finalized in August 2009. This was
after several months of effort and review by members of the RSE Advisory Group. HMC's
observations have been that, while the SOW was followed in general terms, it was not in others.
Several of these areas have been commented on in depth in the body of our comments and will
not be repeated here. One of the significant objects of the evaluation was to "[e]valuate the
adequacy of plume capture, horizontally and vertically, of the groundwater plumes in the alluvial
and Chinle aquifers, using the recent EPA guidance. . . ." As part of that objective it was stated
4
Record of Decision, Homestake Mining Company, Radon Operable Unit, Cibola County, New Mexico. EPA
Region 6, Dallas, Texas, 1989.
May?, 2010 Homestake Mining Company Page 3
-------
that a conceptual model would be evaluated and refined and further that a "limited" assessment
of the approach to groundwater modeling conducted by HMC would be performed. This
objective was not accomplished. To the contrary, the entire report reflects a lack of
understanding of the groundwater system, as well as the fate and transport modeling for the site.
The hydrologic setting of the Grants site is admittedly complex; nevertheless, it has to be
understood in order to draw any inferences or conclusions regarding opportunities, if any, to
improve upon the current remedial systems that are in operation currently at the site.
Another stated objective in the SOW was to assess potential modification to the reverse osmosis
(RO) units and related treatment components to achieve full capacity operations of the treatment
plant. HMC does not see in the Draft RSE Report any suggested changes or additions in this
area.
Another SOW objective was that there would be an attempt to "evaluate the projected
evaporation rates for the new and existing ponds." The conclusions in this area are problematic.
It is understood that a correction has been made in some of the calculations for that effort since
issuance of the Draft RSE Report. Because the present conclusions are not based on the best
possible numbers, we will reserve our comment until that work has been completed. It should
also be noted that, after three years of permitting effort, the third evaporation pond for the project
has been approved and permitted by the State of New Mexico since the issuance of the Draft
RSE Report. This will allow for expanded operation of the present RO treatment system,
irrespective of the debate over needed or necessary storative and evaporative capacity that the
Grants site may need in the future while groundwater remediation efforts advance.
HMC believes the ACOE evaluation was inconsistent and speculative in numerous instances.
The evaluation's recommendations are often contradictory to the report's findings. Many of the
issues raised in the evaluation are based on unsubstantiated stakeholder concerns. HMC believes
the evaluation should be a technical document, limited to factual issues. HMC requests that
ACOE seriously review HMC's responses and comments and revise and/or remove many of the
unsubstantiated and inconsistent recommendations from the final RSE report.
Recommendation No. 1 - The flushing of the tailings pile should be curtailed.
HMC Response:
The ACOE report recommends, in the Executive Summary, that flushing of the tailings pile
should be curtailed: Section 9.2 recommends that the flushing of the tailings pile be
discontinued. HMC disagrees with this recommendation, irrespective of the inconsistency of the
two statements, and it should be removed from the final RSE report. The ACOE
recommendation is based on the following points:
May?, 2010 Homestake Mining Company Page 4
-------
1) Flushing is unlikely to be fully successful at removing most of the original pore fluids.
2) Flushing is unlikely to remediate the source mass in the pile due to heterogeneity.
3) There is a potential for rebounding in contaminants concentrations following cessation of
flushing.
4) The addition of water to the tailings complicates capture of water from the alluvial
aquifer.
FDVIC has evaluated the success of the flushing program in removal of source mass. FDVIC's
response to Recommendation No. 2 (presented later) discusses the mass removed, and Figure 5
of that response shows that the mass is being consistently removed through the flushing program.
As noted by the ACOE, there is a large amount of heterogeneity in the hydraulic conductivities
within the pile due to the presence of low-permeability zones, principally composed of tailings
slimes. However, the flushing program works to overcome this heterogeneity and provide the
driving force for the movement of soluble uranium out of these low-permeability zones. Figure 1
provides a conceptual illustration of the performance of the flushing program.
CD
C
,_ O
^ N
.2 T5
t •> ~
8.11
o ro §
^* "O ^-,
T3 CD
CO
Target
Operation of (2)
Time
CD No flushing
@ Water flushing
Figure 1. Conceptual performance of the large tailings pile with and without flushing.
May 7, 2010
Homestake Mining Company
Page 5
-------
Figure 1 depicts that, although uranium concentrations in the partially saturated alluvial zone
beneath the tailings pile remain elevated for a period of time during flushing (line labeled "2" in
Figure 1), the load to the partially saturated alluvial zone beneath the tailings is much more
effectively controlled. Flushing provides a means to achieve concentrations well below the target
corresponding to a concentration of 2 milligrams per liter (mg/L) underneath the tailings.
Without flushing, uranium load drops off gradually, but concentrations remain high and, due to
continual draindown of pore water with elevated concentrations of uranium, the target is never
achieved (line labeled "1" in Figure 1). The Executive Summary of the ACOE report states as
one of the conclusions that the seepage modeling likely overestimates the efficiency of flushing
of the tailing; however, this is not the case. The model has been able to represent performance of
the flushing program. There is currently a slight lag between actual and predicted performance
because of the inability to flush at full capacity due to the lack of adequate evaporative capacity;
however, this is not a function of model predictability and reliability. The flushing program can
now proceed as planned in light of the recent approval of DP-725 and construction of
Evaporation Pond 3 (EP-3).
With respect to rebound in contaminants following cessation of flushing, this is unlikely given
the following factors:
1) Geochemical conditions in the tailings pore water, and the resultant chemical form of
uranium, that serve to minimize the adsorption or precipitation of uranium in the tailings
2) The aggressive nature of the milling process, in terms of its efficiency at creating soluble
uranium
3) The recalcitrant nature of any uranium that remains in the solid portion of the tailings
These factors are addressed here in detail.
1) The majority of the uranium in the tailings is present in the soluble form due to the
presence of elevated pH and high alkalinity. This is a consequence of the milling process;
the alkaline leach process was very efficient at keeping uranium in solution and is
discussed below. In order to evaluate the chemical form of uranium in the tailings, FDVIC
has performed geochemical modeling using the software Geochemist's Workbench
(Rockware, Golden, CO) and the Lawrence Livermore National Laboratory
thermodynamic database (Delaney and Lundeen 1989) edited to include the most recent
thermodynamic constants for uranium based upon the Nuclear Energy Agency (NEA)
database (NEA 2010) and work by Bernhard et al. 2001 (for the soluble calcium uranium
carbonate complexes). The values provided by NEA have undergone rigorous review and
consideration (by examining the experimental methods and calculations used to derive
them) and were formally accepted only after they withstood critical scientific review. The
May?, 2010 Homestake Mining Company Page 6
-------
tailings pore water chemistry for well EH-11, screened within the tailings impoundment,
is provided in Table 1. The results of geochemical modeling to predict uranium chemical
speciation, based on the tailings pore water chemistry, are provided in Figure 2.
Table 1. Tailings Pore Water Chemistry, Well EH-11 (pH 10).
Constituent
U0,2+
Ca2+
MS2+
Na+
K+
cr
so42-
HCCV
Se6+
Mo6+
mg/L
12.8
3
0.9
3730
13.9
379
3410
1460
0.072
47.5
g/mol
238
40
24
23
39
35
96
61
79
95.9
mM
0.05
0.08
0.04
162
0.36
10.8
35.5
23.9
0.001
0.50
logM
-4.27
-4.127
-4.43
-0.79
-3.45
-1.97
-1.45
-1.62
-6.04
-3.30
Note: Nitrate and vanadium were not detected in pore water.
Geochemical modeling indicates that, at the pH of the pore water (pH 10), uranium is
present as the soluble calcium uranium carbonate complex (Ca2UO2(CO3)3) in the tailings
pore water. The soluble forms of uranium are dominant in the tailings pore water due to
the excess of bicarbonate relative to uranium (Table 1), and similar concentration of
calcium. Under these conditions, it is highly unlikely that any solid phase uranium can
persist beyond the completion of flushing and remain available for re-dissolution. Studies
have shown that uranium present as uranyl carbonate or calcium uranium carbonate is
very poorly sorbed by solid mineral phases (Zheng et al. 2003), and this further supports
the conceptual model based on soluble uranium resident in tailings pore water. Uranium
solid phases are under-saturated (prone to dissolution), and are not expected to form at
the uranium concentration and pH conditions in the pore water (solid phase forms of
uranium are depicted in Figure 2 as yellow areas; soluble uranium is shown as blue
areas).
May 7, 2010 Homestake Mining Company Page 7
-------
CM
O
=>
ro
CD
u
-1
-2
-3
-6
-7
-8
-9
m
'
-
U02SO,«3H20
-
-
U02S04 uc
-
-
I
fto Na,up7(c)
-
Rutherfordine
/
£
UOrfCOaS
^3
I
/
EH1
CajU
.
03(003)3
-
-
25°C
6 8 10 12 14
PH
Figure 2. Results of geochemical modeling of uranium chemical speciation as a function of uranium concentration
and pH. Note that the wells screened in the tailings, EH-11 and EH-13, are shown on the figure, with uranium
present as the calcium uranium carbonate soluble complex in these wells. Note that the y-axis shows the log of the
activity of uranium (uranium concentration).
2) A re-examination of the milling process also leads to the conclusion that very little
uranium persists in solid form. The milling process was aggressive in terms of physical
alteration of the ore and chemical leaching (Skiff and Turner 1981). The result of the
milling process is that it dissolved the majority of uranium present in the ore that could be
released under alkaline leach conditions. In addition, the uranium that remained in the
solids was locked up in recalcitrant, non-leachable forms. Two basic types of ore were
handled at the mill: Sandstone (80 to 85 percent of mill feed) and Limestone (15 to 20
percent of mill feed). The ore consisted of uranium minerals coffinite [U(SiO4)i_x
(OH)4x], uraninite [UO2], tyuyamunite [Ca(UO2)2(VO4)2 ' 5-8 H2O] and carnotite
2 • 3H2O]. The ore was found as an impregnation, a pore filling, or a
May 7, 2010
Homestake Mining Company
PageS
-------
cementation between sand grains. The ore was crushed to an initial particle size of 2
millimeters (mm); the sandstone was ball milled so that 10 percent was greater than 0.3
mm and 35 percent was less than 0.07 mm. The limestone feed was milled twice so that 5
percent was greater than 0.2 mm and 50 percent was less than 0.07 mm. The thickened
slurry was leached in two stages, with the first consisting of a pressure and temperature
leach (at 60 pounds per square inch and 200° F) for 4.5 hours. The second stage consisted
of an air-agitated atmospheric leach at 170° F for 12 hours for the sandstone and 24 hours
for the limestone. The leached slurries were then processed through 3 filtrates stages and
repulped with recycled tailings pond solution and slurried for tailings disposal. Tailings
solution was recovered through decant towers and returned to the mill for soluble
uranium removal (to less than 10 parts per million [ppm]).
3) The ACOE suggests that the large tailings pile contained an estimated 2.6 million pounds
of uranium, present in the tailings at the end of the operation of the mill. This is based on
information provided in EPA-402-R-8-005, Table 3-13; this table acknowledges that
uranium present in tailings after alkaline leaching was present at a much lower
concentration than from tailings after acidic leaching, and may be as low as 0.004
percent. Based upon the details provided in (1) and (2) above, the majority of the uranium
deposited in the tailings pile was soluble and dissolved during the milling process but not
recovered during filtration (i.e., dissolved in water that could not be recovered from the
thickened slurry), and a portion present in recalcitrant mineral phases and as insoluble
crystalline forms of uranium. The flushing process focuses on the soluble uranium; the
insoluble forms will not be soluble in the tailings pore water under current or future
geochemical conditions due to their highly insoluble nature. Any uranium present as
secondary mineral precipitates (i.e., not part of the original minerals in the ore, but re-
precipitated in the tailings) will also be insignificant relative to the dissolved uranium due
to the conditions described in (1) above. A portion of the estimated 2.6 million pounds
will, therefore, always be permanently fixed in the tailings, and flushing has removed an
estimated 520,000 pounds of uranium (see Response No. 2 below) with the remaining
soluble uranium, the only form of uranium of concern for groundwater, to be addressed
through continuation of the flushing program.
With respect to ACOE's evaluation of an in-situ immobilization approach, continuation of the
flushing program will provide the ability to transition to an approach to stabilize uranium
leaching to the partially saturated zone through an augmentation program if determined
appropriate. The augmentation program may be implemented at the appropriate time when it can
be most effective, after flushing has been completed. Figure 3 illustrates the potential benefit of
an augmentation approach.
May 7, 2010 Homestake Mining Company Page 9
-------
o
•IS S
T3 CD
03
CO
Target
Operation of @
Operation of (3
Time
(l) No flushing
(2) Water flushing
(s) Water flushing and augmentation
Figure 3. Conceptual remedial performance of the large tailings pile with and without flushing,
and with flushing and an augmentation approach.
Because of the known occurrence and relatively low permeability of fine-grained materials
(slimes) in the large tailings pile, and the presence of dissolved uranium in the slimes, an option
is to create insoluble forms of uranium through the addition of a phosphate amendment. A
preliminary geochemical modeling evaluation has been performed for the current uranium
chemistry prevalent in the large tailings pile. The aqueous geochemistry data for wells EH-11
and EH-13 indicate that the prevalent forms of uranium in the tailings are soluble uranyl
carbonates (Figure 2). A phosphate amendment (HPC>43~) was simulated and the minerals and
aqueous species with a phosphate treatment solution were found to be stable over most of the pH
range. This was simulated through a geochemical modeling evaluation of the addition of
phosphate to the tailings (Figure 4). These initial conclusions suggest that the flushing of the
tailings should be continued to remove the soluble uranium present in the slimes, then the
remaining low levels of uranium could be fixed by introduction of a phosphate amendment to
form insoluble uranium phosphate minerals, or another amendment that is proven to assist in
remediation. The modeling results, therefore, validate that an in-situ immobilization approach
using sodium tripolyphosphate (reviewed by the ACOE in Section 4.4.3) is feasible; this will be
May 7, 2010
Homestake Mining Company
Page 10
-------
further evaluated for application to the partially saturated alluvial zone underneath the tailings,
and for groundwater where the geochemical conditions are also suitable for its application.
.5
in
.4—*
9
LLJ
-5
25:C
10
12
14
PH
Figure 4. Evaluation of the addition of 1 mM (30 mg/L) of phosphate to the tailings pore water (water chemistry
provided in Table 1). The result of the phosphate addition is precipitation of uranium as UO2HPO4(C), an insoluble
uranium phosphate mineral phase (yellow shaded region on the figure shows the stability field of solid forms of
uranium; the blue shaded area shows the stability field of soluble uranium). Note that the y-axis shows Eh, or a
measure of the oxidation-reduction potential (redox).
In summary, HMC does not believe that the recommendation that tailings flushing be curtailed,
or discontinued, will lead to a better strategy for uranium source reduction in the large tailing
pile. The current source reduction strategy is based on the understanding that the majority of
uranium in the tailings resides as soluble uranium in the pore water, and must be hydraulically
forced out of low permeability zones to effect capture and removal. The flushing program has
shown significant progress (as detailed in our response to Recommendation No. 2, below) and
should continue in order to meet remedial targets. It is highly unlikely that a significant amount
of uranium will be present in a form capable of dissolution upon conclusion of the flushing
program, due to the tailings pore water chemistry that favors soluble uranium, and that prevents
sorption and retention by solids. In addition, an aggressive milling process mobilized the soluble
May 7, 2010
Homestake Mining Company
Page 11
-------
uranium in the ore, and any remaining insoluble uranium will not be mobile. HMC, therefore,
strongly disagrees with the ACOE recommendation and believes that flushing is the most
proactive source reduction option available and to achieve the remediation targets in a timely
manner. We request that Recommendation No. 1 be removed from the final RSE report.
Recommendation No. 2 - Simplification of the extraction and injection system is necessary
to better focus on capture of the flux from under the piles and to significantly reduce
dilution as a component of the remedy.
HMC Response:
HMC believes that the current flushing and extraction system at the large tailings pile has been
effective in removing a substantial amount of uranium and other constituents from the tailings
that would otherwise be available to enter the alluvial aquifer. The ACOE's recommendation to
simplify and better capture the flux under the pile has some merit and HMC plans to re-evaluate
the existing system to possibly achieve more efficient mass removal of the constituents. The
success of the existing system should not be underestimated, however. The hydraulic head
created by the flushing forces uranium in otherwise immobile pore spaces to move out into the
zones where it can be mobilized. Without flushing, this driving force would not exist. The
following briefly discusses the effectiveness of the tailings pile flushing and extraction system
over the last 16 to 18 years and evaluations that HMC may undertake to assess mass recovery.
The effectiveness of the combined flushing and extraction system can be measured by the mass
of uranium removed from the tailings. A graph of the total mass of uranium removed by the toe
drains along the perimeter of the tailings pile and extraction wells in the tailings since 1992 is
provided as Figure 3. The toe drains began in 1992, whereas the extraction wells began operation
in 1995. The cumulative mass of uranium removed from the tailings reached approximately
170,000 pounds by the end of 2009, and the removal rate has been relatively steady through
time, indicating that the system continually removes a substantial amount of uranium in addition
to other constituents such as sulfate, molybdenum, and selenium that also have similar and
steady removal rates. This amount of uranium is no longer available to leach and migrate into the
alluvial aquifer.
Added to the uranium removed by the tailings extraction wells and toe drains, a considerable
amount of uranium has been flushed from the tailings and partially saturated alluvial zone
beneath the tailings pile. This flushing through the partially saturated zone is vital to the success
of mass removal; this mass flux beneath the pile is, or will be, ultimately removed by collection
wells south and west of the pile. The amount of uranium is approximated by multiplying the
average flushing rate through the partially saturated alluvial zone of approximately 150 gallons
per minute (gpm) by the average uranium concentration in the tailings of 30 mg/L and summing
May?, 2010 Homestake Mining Company Page 12
-------
this over the 1992 through 2009 period. The resulting mass of uranium flushed from the alluvial
zone is approximately 350,000 pounds. In total, approximately 520,000 pounds of uranium is
estimated to have been removed from the tailings pile.
The effectiveness of the system is also measured in the overall reduction in uranium
concentration within the tailings pile. The annual average uranium concentrations in the
extraction wells and toe drains are shown on Figure 5. Uranium concentrations from the
extraction wells have decreased from around 40 to 14 mg/L, or an approximate 65 percent
reduction since 1995. The decrease in concentrations from extraction wells is steady. A
regression trend line was fitted to the extraction well concentration data with a coefficient of
9
determination (R ) value of 0.85. The coefficient of determination provides a measure of how
well future outcomes are likely to be predicted by the model, and in this case the linear
regression line. A value near 1.0 indicates that the regression line perfectly fits the data, and the
0.85 value indicates a good fit. The uranium concentration in the toe drains has decreased from
53 to 30 mg/L, or an approximate 34 percent reduction since 1992. The uranium concentration
has fluctuated through time but it has an overall decreasing trend, as depicted by the linear
regression line that has an R2 of 0.61. It is important to point out that the toe drains primarily
remove tailings water from the permeable sand dikes, and this has not been the focus of flushing
remediation to date. Instead, the focus has been on flushing the tailings slimes through the
injection and extractions wells, which addresses the low-mobile mass that is difficult to remove.
After the mass is removed from the slimes, the system can then focus on the mobile mass in the
tailings sands and this is expected to occur relatively quickly. Overall, the system continues to
remove uranium and other constituent mass, and concentrations are steadily decreasing.
The ACOE's recommendation states that "dilution" is a significant component of the current
remedy. HMC believes that a minor degree of dilution may be occurring, but dilution is not as
significant as implied by the ACOE. This is evidenced in the mass of uranium removed and
concentrations presented on Figure 5. If dilution was a significant component of the remedy, the
mass removed would not have a steady cumulative rate as it has had since 1992; instead, the
mass removal would taper off or flatten. Therefore, the fact that mass continues to be removed
at a relatively constant rate combined with concentrations that are decreasing is evidence that
dilution is a minor component.
May?, 2010 Homestake Mining Company Page 13
-------
60
Uranium
Concentration
(mg/L) 50
Pounds of Uranium Removed
from Tailings Pile
Average Uranium
Concentration in Toe
Drains \
Average Uranium
Concentration in
Extraction Wells
180000
160000
140000
120000
40
30
20
10
100000
80000
60000
40000
20000
Cumulative
Pounds of
Uranium
0
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Figure 5. Mass of uranium removed by the large tailing pile extraction wells and toe drains and decreasing uranium
concentrations.
To address the ACOE's recommendation regarding simplification of the system, HMC plans to
evaluate the system and how it is managed and operated. The evaluation may include
recommendations for future modifications to the system operation, should they be found to
increase the effectiveness of the system to reduce constituent concentrations and capture of
tailing seepage. The following describes evaluations that HMC may perform.
Water Balance - HMC plans to use available data to prepare annual water balances for the large
tailings pile since the late 1990s. Data for the volume of rinse water, extracted water, and toe
drain water will be used to approximate the amount of water that may flow out of the tailings pile
into the alluvial aquifer. This type of a water balance evaluation has been done in the past, and it
will be re-examined and expanded to create a historical perspective on the tailings pile water
balance. The water balances provide information on how much water is flushed through the
partially saturated alluvial zone beneath the tailings pile. It is important to realize, however, that
a certain amount of water is needed to flush the partially saturated zone beneath the tailings pile
May 7, 2010
Homestake Mining Company
Page 14
-------
to flush mass from this zone into the alluvial aquifer, where it can be extracted by collection
wells around the perimeter of the tailings pile. This can only be achieved by allowing some of
the flushing water to flow through the partially saturated zone beneath the tailings pile.
Mass-Flux Evaluation - Building on the water balance evaluation above, HMC plans to perform
a mass-flux evaluation of the large tailings pile. Flux-informed evaluations are useful in
characterization and aid in remedial decision making. The first component of the evaluation is to
estimate the mass of constituents stored in the fine-grained tailings (slimes) and in the coarse-
grained tailings. This provides an understanding of the "mobile" mass that can be remediated
using the current flushing and extraction system. The mass stored in the fine-grained tailings is
less mobile, and the evaluation may find that flushing of the fine-grained tailings could be
curtailed or eliminated because of its very low mass flux. The hydraulic flux (pumping) at each
injection well and mass flux (concentration x pumping rate) at each extraction well will be
estimated to provide information on where the highest flushing rates occur and the relationship to
where the greatest mass removal occurs. The goal of the mass-flux evaluation is to optimize the
mass removal rate. Results of the mass-flux evaluation may identify wells or certain areas of the
tailings pile where flushing could be curtailed.
Recommendation No. 3 - Further evaluate capture of contaminants west of the
northwestern corner of the large tailings pile.
HMC Response:
The saturated thickness of the alluvial aquifer northwest of the large tailings pile is limited, and
the zero saturation line is less than approximately 1,000 feet northwest of the pile. Previous
testing in this area indicated that well yields of greater than 1 gpm could not be sustained, which
prohibits effective extraction. Therefore, several fresh water injection wells and injection lines
were installed west of the pile to create a hydraulic barrier and limit the westerly migration from
the large tailings pile. The injection also increases the saturated thickness of the alluvial aquifer
in the area. The hydraulic barrier is illustrated on Figure 4.2-1 of the 2008 Annual Monitoring
Report (FDVIC and Hydro-Engineering, LLC. 2009) where the water in the area of injection is
approximately 10 feet higher than at the western toe of the tailings pile. The other remedial
component in this area includes collection wells between the toe of the tailings pile and the
injection wells/lines. The injection combined with collection near the toe of the tailings pile has
been effective at remediating the alluvial aquifer west of the large tailings pile. Without the
injection the collection wells alone would have limited effectiveness.
The ACOE's recommendation to further investigate capture of constituents west and northwest
of the large tailings pile may have value. However, HMC must point out that this is a relatively
May?, 2010 Homestake Mining Company Page 15
-------
small portion of the site that has minimal potential exposure to residents or workers. HMC plans
to assess the available injection/collection data, water levels, and chemical data in these areas
and re-evaluate the effectiveness of capture system. The increased saturated thickness due to
fresh water injection could have altered local groundwater flow directions resulting in some
bypass of tailing seepage around the hydraulic barrier created by the injection. Because the zero
saturation line for the alluvial aquifer is a relatively short distance northwest of the tailings pile,
the focus of the re-evaluation should be the area west of the tailings pile. Adjustments to the
existing injection/collection system may be considered to achieve more effective capture.
Recommendation No. 4 - If not previously assessed, consider investigating the potential for
contaminant mass loading on the ground water in the vicinity of the former mill site.
HMC Response:
HMC is uncertain of the basis for this recommendation because demolition of the mill and cover
of former mill area is well-documented. The former mill and associated structures were
decommissioned between 1993 and 1995, which was approved by the U.S. Nuclear Regulatory
Commission (NRC). Beginning in 1993, the major mill structures were demolished and the
debris was buried on site in a total of eight pits. Five of the eight pits were in the mill area
between the large tailings pile and State Road 605, and the remaining three pits were between the
large tailings pile and evaporation ponds #1 and #2. Demolition debris primarily consisted of
metal and wood from buildings, milling equipment including thickeners, roasters, and dryers,
and concrete foundations. Pits were typically 20 feet deep and debris was placed into the pits in
5-foot lifts. After each lift was in place, a slurry grout was pumped into the pit to fill voids
around the debris and solidify the debris. Once filled, a soil cover was place over the pits and
surrounding areas and graded for positive drainage. The soil cover was approximately 2 feet
thick over the mill area, but the cover was thicker (4 to 5 feet) over some of the pits. A diversion
levee north of the mill area was also constructed to divert runoff from flowing over the mill area.
A gamma survey was performed after the cover was in place to measure the effectiveness of the
cover to restrict radionuclide emissions. As-built and completion documents are contained in
Completion Report - Mill Decommissioning, Homestake Mining Company, Grants Uranium
Mill, February 29, 1996. Quality control of earthwork and cover construction is documented in a
Construction and Quality Control Report by Knight Piesold, May 17, 1996.
The slurry grout that was used to solidify the mill debris in the burial pits is believed to have
effectively entombed the debris and prevented its contact with the surrounding environment.
This solidification, combined with the engineered cover and storm water controls that limit
percolation of water through the pits, significantly restricts potential leaching of uranium and
radionuclides from the debris. The depth to water in the alluvial aquifer at the former mill is
approximately 35 feet on average and deeper at approximately 50 feet between the large tailings
May?, 2010 Homestake Mining Company Page 16
-------
pile and the evaporation ponds, where pits #4 and #5 are located. Considering that the pits were
typically 20 feet deep, the bottoms of the pits are 15 to 30 feet above the water table. Potential
leaching of the solidified debris in the pits would have to first migrate through this unsaturated
zone before reaching the water table. Given the low precipitation in the area and storm water
run-on and run-off controls, it is highly unlikely that leaching of the stabilized debris is a source
of contaminants to the alluvial aquifer.
A cluster of alluvial monitoring wells is located southeast of the former mill and south of several
of the pits at the former mill site. Uranium concentrations in this area are variable over short
distances. This is in an area where an in situ biological test is situated with associated water
injection, which may be the source of some of the variability. The source of the elevated uranium
is believed to be residual tailings seepage from the large tailings pile. However, injection south
of this area has created a groundwater "high" and the groundwater flow direction in the alluvial
aquifer is to the west. Collection wells in the area west of the mill also facilitate this westerly
groundwater flow. Therefore, alluvial groundwater in the former mill area should flow toward
the collection wells between the large tailings pile and evaporation pond #1. Burial pits #4 and
#5, which are between the large tailings pile and the evaporation ponds, are also in this area of
groundwater collection.
Evidence for this westerly flow direction is from concentration observations in alluvial well 1M,
which is south of the mill between evaporation pond #1 and State Road 605. The 2008 uranium
concentration in the well was 0.013 mg/L, and other constituents including molybdenum and
selenium, were not detected. If there was a southerly flow direction from the mill and burial pit
at the mill site, concentrations would be much higher in well 1M, but this has not been observed.
There are numerous monitoring wells in the former mill area and the injection and extraction
system is controlling the migration of any site-related constituents. In the unlikely event that the
stabilized mill debris in the pits produces leachate, the leachate would be collected in extraction
wells west of the mill. For these reasons, HMC does not believe that additional investigations of
the mill area are necessary and the ACOE's recommendation should be removed from the final
RSE report.
Recommendation No. 5 - Further investigate the extent of contaminants, particularly
uranium, in the Upper and Middle Chinle aquifers and resolve questions regarding
dramatically different water levels among wells in the Middle Chinle.
HMC Response:
The ACOE's recommendation to further investigate uranium concentrations in the Upper and
Chinle aquifer is inconsistent with its interpretations stated the Draft RSE Report. Section 3.5,
Page 16 states: "Performance for the extraction system in the Upper Chinle aquifer appears to
May?, 2010 Homestake Mining Company Page 17
-------
be adequate." It is unclear why the ACOE recommends further investigation of the Upper Chinle
aquifer when it interprets the performance of remediation in the Upper Chinle aquifer to be
adequate. The performance is presumably based on an adequate level of monitoring in the area,
yet there is a recommendation for further monitoring. HMC agrees that the collection and fresh
water injection system in the Upper Chinle aquifer is performing well, as documented in the
2008 Annual Monitoring Report (HMC and Hydro-Engineering, LLC. 2009). As depicted on the
water level elevation map on Figure 5.2-1 of the report, the collection wells in the Upper Chinle
aquifer immediately south of the large tailings pile effectively create a hydraulic capture zone
that collects groundwater with elevated uranium and other constituents. This collection system,
combined with the fresh water injection further to the south between the collection wells and
Broadview Acres, controls the off-site migration as shown on the uranium iso-concentration
contour map, Figure 5.3-11 of the report.
A number of Upper Chinle aquifer wells are strategically positioned on site to monitor potential
migration from the large tailings pile, evaporation pond #1 and #2, and the small tailings pile.
Monitoring wells are also located downgradient and off site in Broadview Acres and Felice
Acres. Areas that exceed the site uranium standard in the Upper Chinle aquifer are limited to the
large tailings pile south to the collection pond and #2 evaporation pond, and localized areas in
Broadview Acres and Felice Acres. However, an adequate number of wells surround each of
these areas and, when combined with an understanding of the groundwater flow direction that is
depicted on Figure 5.2-1 of the Annual Monitoring Report, the extent of uranium is defined.
As discussed below, ACOE's recommendation to resolve the difference in water levels among
wells completed in the Middle Chinle aquifer is not warranted and further investigation of the
extent of uranium is also not needed as discussed below.
First, the variable water levels in the Middle Chinle aquifer are adequately explained in Section
6.2 of the 2008 Annual Monitoring Report (HMC and Hydro-Engineering, LLC. 2009) and are
summarized below. As illustrated on the water level map of the Middle Chinle aquifer in the
report (Figure 6.2-1), steep gradients occur along the alluvial subcrop south of Felice Acres,
which are due to recharge of water from the alluvial aquifer. Collection of water from CW-1 and
CW-2 immediately north of the large tailings piles lowers water levels by 20 to 30 feet and
creates a zone of hydraulic capture near the pile. Another area of large differences in water levels
is north of Broadview Acres and southwest of Felice Acres where the injection of fresh water
into wells CW14 and CW30 has created localized groundwater mounds in the areas of these
wells that are approximately 50 to 70 feet higher than water levels that are farther away from the
injection. The west and east faults that bound the site influence water levels by restricting flow,
which results in lower water levels between the two faults. Groundwater does not readily flow
across the faults. The 2008 Annual Monitoring Report contains water level hydrographs of
May?, 2010 Homestake Mining Company Page 18
-------
select wells (Figures 6.2-3 and 6.2-4), and the variable water levels shown on the graphs may be
the source of the ACOE's comment on the alleged "dramatically" different water levels.
However, the variable water levels in collection wells are explained by measurements taken
during times of pumping and non-pumping when water levels have recovered. Some of the
variation in water levels is also explained by variable pumping rates in some of the collection
wells. There is a noticeable difference in water levels in wells west of the west fault that are 80
to 100 feet higher than water levels between the west and east faults. These differences are
explained by the west fault restricting flow across the fault. A closer review by the ACOE of the
site's hydrogeology and operation of the injection and collection system in the Middle Chinle
aquifer would have found that the differences in water levels can be explained.
The second recommendation by the ACOE is to further investigate the extent of uranium in the
Middle Chinle aquifer. As shown on Figure 6.3-11 of the 2008 Annual Monitoring Report,
uranium concentrations greater than the site standard are limited to an area west of the west fault,
in Broadview Acres and south of Felice Acres, and immediately north of the large tailings pile,
although this area is minimally above the site standard. The area west of the west fault has wells
surrounding the location of elevated uranium in CW-17, and the area is physically bounded on
the west by the zero saturation restriction and the west fault. The elevated uranium
concentrations at Broadview Acres and Felice Acres is bounded by wells to the east, fresh water
injection on the west, and the subcrop extent of the Middle Chinle formation on the south. The
localized area of elevated uranium immediately north of the large tailings pile is in an area of
hydraulic control due to groundwater collection.
Overall, the large differences in water levels that are pointed out by the ACOE can be explained
by the site's complex hydrogeology, geologic structure, and operation of the injection and
extraction system. FDVIC believes that the existing monitoring of the Upper and Middle Chinle
aquifers is adequate from a site-wide perspective and for areas where constituent concentrations
are greater than site standards.
Recommendation No. 6 - Consider geophysical techniques, such as electrical resistivity
tomography to assess leakage under the evaporation ponds.
HMC Response:
The ACOE states in Section 4.3 that there is no obvious evidence of leaks in the evaporation
ponds, and evaluated this by comparing water levels in the ponds and in nearby wells. Except for
the error noted in the top of casing elevation for some of the C series wells (this was a database
error that has been corrected), the water levels did not indicate any leakage. While Evaporation
Pond 1 (EP-1) does not have a leak detection system, Evaporation Pond 2 (EP-2) does possess a
May?, 2010 Homestake Mining Company Page 19
-------
leak detection system and is double-lined. However, there is an active collection system of wells
that would collect any water that might seep away from EP-1 in the event of a leak.
Two-dimensional (2D) resistivity might be able to ascertain the integrity of the evaporation
ponds by placing multiple 2D lines tangential to the margin of the evaporation ponds to allow
imaging along these margins. Fluid migrating out of the ponds would have very high total
dissolved solids and are, therefore, highly conductive. However, the geophysical survey would
not be able to provide any information on leakage rates and would therefore not provide useful
information. Given that the technique could not provide information on the magnitude of the
leakage (e.g., flow rates), the results would not be actionable relative to altering the current
strategy. Additionally, water flowing into, within, and around the ponds create self potentials
(electric field induced naturally by the water) which would induce electrical noise into the
geophysical measurement and significantly reduce the accuracy of the survey. Two-dimensional
resistivity would not provide information on the area directly beneath the ponds due to the
inability to run lines directly across them. Any vertical fluid loss would not be detected.
A better approach is to examine water levels in the pond and adjacent wells; this was evaluated
by ACOE and, as discussed above, did not show any evidence of leakage. Currently, the flow at
the margins of the evaporation ponds is to the wells to the northwest; therefore, any potential
leakage would be collected and contained in the current collection well system south of the large
tailings pile.
Recommendation No. 7 - Assure decommissioning of any potentially compromised wells
screened in the San Andres Formation is completed as soon as possible.
HMC Response:
The ACOE's recommendation to decommission any San Andres Aquifer well that has a
compromised screen is a good point to ensure the continued protection of the aquifer. There are
23 wells in the site vicinity that are completed in the San Andres Aquifer. About half of these
wells are included in the site's monitoring program. 2008 concentration data from aquifer wells
are similar to historical values; the consistent concentrations through time indicate that the
aquifer is not impacted by constituents typically found in tailings seepage. This also suggests
that, in the unlikely event that there is a compromised well screen, it has not resulted in cross-
contamination into the deep aquifer. The ACOE apparently has this same interpretation, as
mentioned in Section 3.6 Page 16 of their Draft RSE Report, which states: "A review of water
quality data and water levels for the relatively few wells screened in the San Andres Formation
was conducted. Though few data were available, there was no evidence of contaminant impacts
to these wells. Water levels were reasonably consistent and indicated a ground water flow
direction in the San Andres toward the northeast'' The following outlines HMC's approach to
evaluating potential compromised monitoring wells and supply wells.
May?, 2010 Homestake Mining Company Page 20
-------
HMC plans to review available borehole logs for San Andres Aquifer monitoring wells and
identify those which have screens or gravel packs that extend up into the overlying Chinle
Formation that could potentially allow from possible cross-contamination. Available water levels
will also be reviewed to determine if a particular well's water level is consistent with other San
Andres Aquifer wells. The aquifer is confined, and the potentiometric surface is lower than water
levels in the overlying Chinle Formation and alluvial aquifer; therefore, a water level that is
similar to water levels in the overlying aquifers could indicate that the well screen has
hydraulically connected aquifers. FDVIC may also employ down-hole video to evaluate the
integrity of suspect well screens. If a well is suspected of cross-contaminating the San Andres
Aquifer, the well may be pumped to determine the extent of contamination. FDVIC has already
done this at private well 986 east of Valle Verde and found that the low concentration of uranium
decreased to values typical of the San Andres Aquifer (0.01 mg/L or less) after a short period of
pumping. Therefore, the suspected leakage from the alluvial aquifer or Lower Chinle aquifer
may be enough to slightly increase the uranium concentration in the well casing, but it is not
affecting the San Andres Aquifer water quality. Monitoring wells that are proven to contaminate
the San Andres Aquifer by compromised well screens will be properly abandoned in accordance
with New Mexico regulations in New Mexico Administrative Code 19.27.4.31, Part K, Plugging
Requirements for artesian wells. It is important to point out that some of the San Andres Aquifer
wells are on private property. If found to have compromised well screens or if well screens
hydraulically connect shallow and deep aquifers, abandonment of these private wells would be
the responsibility of the owners, not HMC.
HMC operates two San Andres wells (#1 Deep and #2 Deep) that are used to supply the fresh-
water injection systems within the collection area. Also, San Andres well 951 is used as the
fresh-water injection supply for the injection system in Sections 28 and 29, and San Andres well
943 is used as the fresh-water injection supply for the injection system in Sections 3 and 35 and
Felice Acres. HMC will not abandon these supply wells because they are vital to the injection
system. The supply wells are heavily pumped and potential migration of constituents from
shallow aquifer to the deeper is unlikely because of the pumping. Review of the water chemistry
from these supply wells indicates that they are not impacted by site-related constituents such as
uranium and sulfate. HMC will continue to evaluate the supply wells and, if found to have a
compromised well screen that results in cross-contamination of the San Andres Aquifer, HMC
may consider modifying the well screens or otherwise address the issue for that particular well.
The Draft RSE Report specifically identified well 0806 to be decommissioned because it was
replaced by well 0806R. Well 0806 is located at the northern part of Murray Acres and has an
opening in the casing near the water level in the Chinle shale interval. The alluvial and Lower
Chinle aquifers in this area have very low uranium concentrations; thus, it is unlikely that the
May?, 2010 Homestake Mining Company Page 21
-------
opening in well 0806 is affecting the San Andres Aquifer water quality. The 2008 uranium
concentration in 0806R, which is about 60 feet away, was low at 0.018 mg/L and typical of other
San Andres Aquifer wells. HMC is in ongoing discussions with the Office of the State Engineer
to abandon well 0806.
Recommendation No. 8 - Consider construction of a slurry wall or PRB around the site to
control contaminant migration from the tailings piles. The decision for implementing such
an alternative would depend on the economics of the situation.
HMC Response:
Under the alternative strategies evaluated by the ACOE, construction of a slurry wall around the
entire tailings pile and a permeable reactive barrier (PRB) downgradient of about half of the
tailings pile are two remedial technologies recommended for additional study as alternatives to
the current extraction/injection strategy. HMC has evaluated slurry walls and PRBs as possible
remedial options and found them to be difficult to construct and ineffective given the site
conditions and they could result in incomplete isolation and capture of tailing seepage migration.
The following elaborates on slurry walls and PRBs and their applicability as alternative remedial
strategies.
Construction of a slurry wall would require trenching or excavation through the entire thickness
of the alluvium, which is known to reach depths of approximately 120 feet based on the available
borehole information and depth to the base of the alluvium. The actual depth of a potential slurry
wall would be greater than this near the southwest corner of the large tailings pile because the
Upper Chinle aquifer is in direct contact with the alluvium and the wall would have to extend to
the base of the Upper Chinle, which would be another 20 feet, making the overall depth of the
wall closer to 140 feet. Well CE7 is in this area and it is screened in the upper Chinle aquifer
from 100 to 140 feet. At another site, the U. S Department of Energy (DOE) has rejected similar
trenching proposals in the immediate vicinity of the pile as a permanent remedial solution.
The success or failure of a slurry wall depends on continuous placement of the low-permeability
slurry through the alluvium so that it is keyed into the underlying bedrock (Chinle shale) to cut
off potential groundwater flow along the contact between alluvium and shale. This would require
additional excavation into the shale of at least 5 feet, resulting in a maximum depth of at least
145 feet. It is important to note that Chinle shale may have thin layers of sandstone, and the
depth could be even greater to reach low-permeability competent shale.
Although trenching technologies may be feasible at such depths, it is difficult to ensure
continuity of a slurry wall. During construction, the trench would be inspected for width, depth,
key penetration, verticality, continuity, stability, and bottom cleaning. The EPA guidance on
May?, 2010 Homestake Mining Company Page 22
-------
subsurface engineered barriers recognizes these important factors for successful slurry walls,
stating that below about 100 feet the verticality and thus the continuity of grout barriers are
difficult to control or confirm (EPA 1998). Another difficulty associated with slurry walls is
excavating a key into the underlying bedrock. Depending on the hardness of the shale, blasting
may be required. In addition to the fact that the depth of the slurry wall could reach 145 feet, the
length of the slurry wall that would be required to isolate the tailings migration is estimated to be
13,000 feet or 2.5 miles. HMC knows of no slurry walls of this length and depth that have been
constructed, much less successfully operated. Given that the continuity of a slurry wall is
difficult to confirm at such great depths and the tremendous length of the wall, it is likely that
complete continuity of the wall could not be achieved or maintained.
The ACOE cites two projects where slurry walls have been used: the 9* Avenue Dump in Gary,
Indiana and Lipari Landfill in Glassboro, New Jersey. The 9* Avenue Dump is located in a
marsh area with a shallow water table and the slurry wall was about 30 feet deep. The Lipari
Landfill is in a similar setting and the slurry wall was also about 30 feet deep. These two sites
are significantly different from the Grants site, where the depth of a slurry wall would be nearly
five times greater. Therefore, these two sites are not appropriate references for the Grants site,
where the slurry wall could be more than 145 feet deep in certain places.
A PRB would suffer the same difficulties and uncertainties as a slurry wall. The trench for the
PRB would have to be excavated to depths of up to 145 feet and also keyed into the underlying
Chinle shale. The PRB that ACOE evaluated was a funnel and gate barrier, where two slurry
walls would be used to direct groundwater to an 800-foot long gate or PRB where the water
would be treated in situ. Installing a PRB to depths of 145 feet would be technically challenging
with a high potential for failure. Unlike a slurry wall, where the slurry is used to keep the
excavation open, the continuity of the reactive material forming the PRB would likely be
compromised by sloughing of excavation when the reactive material is put in place.
Furthermore, PRBs are prone to clogging as constituents, in this case uranium and other dissolve
inorganics, would precipitate within the PRB. This would lead to reduced permeability of the
reactive barrier, as the ACOE correctly mentions (citing information from a PRB installed at the
Denver Federal Center in Lakewood, Colorado) and over time, the PRB may have to be replaced.
Replacement costs were not factored into the ACOE cost estimate of $19,000,000. The PRB at
the Denver Federal Center has also experienced other problems of reduced permeability that
occurred during trench excavation. The trenching equipment created a smear zone along the
sides of the trench that reduced the permeability such that groundwater mounded behind the
PRB. This smearing, in all likelihood, would also occur at the Grants site, and it would be
difficult to monitor and prevent at a depth of 145 feet. As mentioned by the ACOE, a PRB would
need future maintenance or replacement, which is contrary to DOE's desire to have no long-term
legacy remediation maintenance requirements. Such proposals are in direct opposition to DOE's
May?, 2010 Homestake Mining Company Page 23
-------
preference for passive remediation systems at uranium mill tailings sites (see 40 CFR Part 190,
Appendix A, Criterion 12).
The ACOE cites a PRB at the Fry Canyon site in Utah that was installed to remove uranium from
groundwater. The PRB used three reactive materials: zero-valent iron, ferric iron, and phosphate,
with the zero-valent iron having the highest uranium removal percentage. A funnel and gate
method was used where the PRBs, or gates, were 3 feet thick, 7 feet wide, and about 4 feet deep.
Although the PRBs had high uranium removal rates, the shallow depth of only 4 feet made the
PRBs a very viable and constructible remedial option, whereas the depth of a PRB at the Grants
site would be up to 145 feet, or potentially deeper. In fact, the Fry Canyon study cited by the
ACOE (EPA and U.S. Geological Survey [USGS] 2000) states that PRBs have been installed at
depths of no more than 45 feet. This acknowledgement by EPA and the USGS substantiates the
difficulty and impracticability of installing deep PRBs.
The ACOE notes that there is a potential for migration of contaminants through the Upper Chinle
aquifer that subcrops under the large tailings pile. This potential would still exist if a slurry wall
or PRB is constructed and may require continued extraction and treatment of groundwater.
HMC has evaluated the economics and implementability of a slurry wall and PRB and found
them to be impractical and cost-prohibitive remedial options given the difficulty of construction
and likelihood of incomplete isolation or collection of the alluvial groundwater because of the
excessive depth of excavations. As noted by the ACOE, there would still remain a potential for
migration into the Upper Chinle Formation that would require continued extraction of
groundwater. Therefore, HMC believes that the current extraction and injection remediation
strategy is the most cost-effective alternative, and the difficulties associated with constructing an
effective slurry wall or PRB limits these technologies from further consideration. The ACOE's
recommendation for further evaluation of slurry walls and PRBs should be removed from the
final RSE report.
Recommendation No. 9 - Relocation of the tailings should not be considered further given
the risks to the community and workers and the greenhouse gas emissions that would be
generated during such work.
HMC Response:
HMC agrees that relocation of the tailings should not be considered further. HMC also believes
that it is important to re-emphasize that this "Alternative Strategy" would create a significant risk
to human health. The ACOE's analysis reveals that at least three fatalities may be caused due to
transport of tailings on public roadways; it is likely that the loss of life would be even greater due
to the use of heavy trucks and limited maneuverability of these trucks under heavy load. While
May?, 2010 Homestake Mining Company Page 24
-------
the concern over carbon dioxide emission is also stated, and placed as a consideration of
paramount importance in recommending against this alternative, it is clear that the very real
potential for loss of multiple human lives should be first and foremost, and enough to discount
this alternative.
Recommendation No. 10 - If geotechnical considerations allow, consider expansion of the
evaporation pond on the small tailings pile as means to enhance evaporative capacity.
HMC Response:
The recommendations provided with respect to the expansion of evaporative capacity or
reduction in discharge to the ponds are clearly based on an understanding by the ACOE that
additional evaporative capacity is needed for optimal functioning of the remedial system. This
has also been recognized by the State of New Mexico, with the recent approval of DP-725 for the
construction of EP-3. In light of this, the recommendation to expand the evaporation pond on the
small tailings is not appropriate. In addition, expansion would be difficult due to geotechnical
considerations. The expanded pond would need to be tied into EP-1; this would pose a
geotechnical challenge and would possibly compromise the liner system of EP-1.
Recommendation No. 11 - Consider either the pretreatment of high concentration wastes in
the collection ponds as is currently being pilot tested, or adding RO capacity to increase
treatment plant throughput and reduce discharge to the ponds.
HMC Response:
This recommendation is based on an evaluation by ACOE of the reverse osmosis (RO) treatment
plant, and is provided as a means to enhance the operation of the remedial system so that the
plant can operate at full capacity. As with Recommendation No. 10 above, the ACOE recognizes
the need for enhanced evaporative capacity and pond storage. The RO treatment plant will be
able to operate at its full potential, with the recent approval of DP-725, and additional RO
capacity is therefore not needed in order to increase plant throughput. HMC continues to
evaluate the pre-treatment of water in the collection pond through the addition of extracted
tailings water, with elevated concentrations of bicarbonate, and groundwater containing elevated
concentrations of calcium. The purpose of the pre-treatment is to facilitate the precipitation of
calcium carbonate and to limit the need for this treatment at the RO plant.
May?, 2010 Homestake Mining Company Page 25
-------
Recommendation No. 12 - Develop a comprehensive, regular, and objectives-based
monitoring program. Quantitative long-term monitoring optimization techniques are
highly recommended.
HMC Response:
HMC agrees that the monitoring program for the Grants site should be comprehensive and based
on specific objectives for particular areas of the site, as well as for the entire site. Currently,
HMC performs substantially more monitoring than what is required under existing permits.
Approximately 80 monitoring wells are required to be sampled, but as needed, HMC voluntarily
samples several hundred additional wells to assess the performance of the injection/collection
systems and extent of impacted groundwater. This demonstrates HMC's commitment to the
remediation of the Grants site.
The ACOE's recommendation to optimize the monitoring program has potential benefit in the
long term to determine if the monitoring well network can be streamlined while still meeting the
future needs of the project. HMC plans to evaluate the site groundwater monitoring program,
which includes identifying and categorizing wells and their intended purpose, followed by
evaluating each monitoring well and determining its inclusion or exclusion in the monitoring
program. HMC plans to perform this procedure for those monitoring wells that are required
under state permits or federal license as detailed below.
Define Monitoring and Develop Objectives - The first step includes identify monitoring wells
at the site and pertinent information associated with each well; including date drilled, depth,
casing size, screened interval and formation, location, and any possible issues with the well.
Additional information, such as period of chemical and water level data and frequency of
sampling, will be summarized for each well. The original and current objective of each
monitoring well will be identified or formulated if the purpose of the well is uncertain. The
relative location of a particular well to a source area, such as the large tailings pile, will be used
to assist in developing the monitoring objectives. The outcome of this first step is a
comprehensive tabulation of monitoring well information and objectives of the monitoring.
Monitoring Optimization - The second step in the planned process consists of analyzing
historical data using simple statistical methods and a rule-based decision process to determine if
continued or additional sampling of the existing monitoring wells will provide data relevant to
characterization of known impacts. The planned analysis compares historical data collected from
monitoring wells to the most recent round of sampling. Recent and long-term data will be
evaluated using a simple rule-based decision process to determine an adequate sampling
frequency based on intrawell concentrations of the selected constituents. HMC plans to use
simple and widely accepted statistical tests that have been applied successfully on numerous
May?, 2010 Homestake Mining Company Page 26
-------
contaminated groundwater sites. Several lines of evidence may be evaluated to determine if
monitoring well sampling parameters and frequency are suitable. These include:
• Number of samples collected since the installation remediation started,
• Frequency of detection in recent sampling events,
• Maximum detected concentrations,
• Concentration-time profiles for the full and recent datasets,
• Magnitude of the annual concentration change with respect to important health
protection, levels (i.e., site standard), and
• Predictability/variability of the concentrations over time.
Each well is then subjected to a decision process, and Figure 6 is an example of a commonly
used systematic approach for evaluation and optimizing a monitoring program. Data sets are first
evaluated to determine that sufficient samples have been collected. Historical and recent trends
are evaluated to identify both long-term and short-term concentration trends, and the direction
and magnitude of the trend can be evaluated using the relatively simple statistical tests. If no
statistically significant trend is detected, the well and constituent is proposed for continued
sampling at the current frequency. If a statistically significant trend is identified, the magnitude
of change is evaluated with respect to the site standard. In this way, rapidly changing
concentrations can indicate an important change in conditions of the plume. Wells with rapidly
changing concentrations would be proposed for continued monitoring at the current frequency.
Wells with negligible annual change, including those above the site standard, do not benefit from
more frequent sampling and are, therefore, proposed for a lower frequency. Moreover, wells with
recent trends that are similar to the overall long-term trends can be reduced to annual sampling.
Because concentrations are predictable and more frequent sampling does not yield additional
information. Final recommendations are subjected to scientific and engineering review to ensure
that the proposed sampling program would continue to meet program needs and related permit
requirements.
May?, 2010 Homestake Mining Company Page 27
-------
Well sampled at least 8
times?
No _
.
Yes
Detected?
No ..
Remove
Yes
Max detect a) > Std. or
b) < Std. with increasing
trend?
Trend Observed
i
, Yes
Calculate annual change
No
Maintain
an half
gligible)
Less than Std.
(moderate)
• i
lual
r
Semi-annual
i
Grec
Std. (s
Malnta
Compare recent and
historical trends
Evaluate recent data for wells.
If concentrations have been below
detection for the most recent eight
events, consider removing
well/analyte from program.
If concentrations are below the Std.
and not increasing, consider
removing well/analyte from
program.
When data are above the Std. with
no detectable trend, continue
current sampling frequency.
When data are above the Std. and
exhibit a detectable trend, calculate
the annual concentration change.
When the annual change is less
than the Std., the change is slow
with respect to the Std.
When the annual change is
substantial (> Std.), consider
monitoring at least semi-annually.
After making recommendations
based on recent data, evaluate the
recent data compared to the
historical data.
If recent and historical trends are
similar and concentrations are
strongly correlated with time (R2
>Q.7)then consider decreasing
frequency since concentrations are
generally predictable overtime.
After preliminary frequency are
suggested by the system,
recommendations are reviewed
scientifically with respect to site
knowledge, well purpose, proximity
to potential receptors, etc.
Figure 6. Decision support process for sampling optimization
Recommendation No. 13 - Adjust Air Monitoring Program to perform sampling of radon
decay products to confirm equilibrium assumption, consider use of multiple radon
background locations to better represent the distribution of potential concentrations and
assess the radon gas potentially released from the evaporation ponds, especially during
active spraying.
HMC Response:
The ACOE summary review of the monitoring program concludes that the program meets the
requirements of the Nuclear Regulatory Commission Regulatory Guide 4.14 (Radiological
Effluent and Environmental Monitoring at Uranium Mills). Reports detailing the monitoring
May 7, 2010
Homestake Mining Company
Page 28
-------
results are submitted to the NRC annually. HMC does not believe that any adjustment to the air
monitoring program is required with respect to the radon decay products as well as the
evaporation ponds. HMC is evaluating the location of the radon background monitor, and will
work with NRC on this evaluation.
The ACOE requests that wind direction data be obtained during each monitoring period; this
information is collected and maintained by HMC. Attachment B provides a wind rose
summarizing data collected for some of the monitoring period during 2008.
Estimate of Radon Daughters - Radon, which is released during low wind conditions, moves
primarily toward the HMC #4 and HMC #5 monitoring stations. The attached wind rose data
show that this occurs approximately 20 percent of the time (blue in wind rose chart). During
higher wind conditions, the radon is transported primarily in other directions and is quickly
dispersed. As radon ages, the concentration of radon daughters increases relative to the radon
concentration (higher equilibrium). Therefore, under high wind conditions, the concentration in
air of radon daughters accumulated from radon released from the site is very small, and may be
higher under low wind conditions. In order to calculate a dose to the nearest neighbors, HMC
selected a radon daughter equilibrium factor of 20 percent. Details of the basis for this selection
are discussed here.
ACOE incorrectly suggests that the NRC Reg. Guide 8.30 specified method is appropriate for
measuring the equilibrium ratio at the site. The suggested Modified Kusnetz method is a grab
sample technique that would be inappropriate for use outdoors under variable wind and other
atmospheric conditions. It would be difficult to interpret grab sample results because radon
progeny concentrations are reduced by attaching to dust particles or scrubbed from the air by
moisture. In addition, it would be nearly impossible to quantify the contribution of radon
progeny from natural background radon to the measured working levels at any point near the
site.
The selection of 20 percent equilibrium is a conservative estimate. If radon is released and the
radon and decay products travel together toward the site perimeter, calculations show that the
percent equilibrium starts at zero upon release and reaches 20 percent equilibrium after 32
minutes. In the wind rose chart for the HMC site (Attachment B), the winds represented by the
"blue color" are low speed, directed toward the southwest, and thus are dominant for radon
transport. They represent winds in the range of 0.5 to 2.1 meters/second. After 32 minutes, these
winds would have swept the radon and daughters downwind to a distance ranging from 960 to
4,032 meters, or 3,150 to 13,200 feet. The two monitoring stations HMC#4 and HMC#5 are at
approximately 2,500 feet and 3,500 feet from the large tailings pile. Therefore, the equilibrium at
the farthest station (3,500 ft) would be expected to be approximately 20 percent for the 0.5
meters/second winds but less than 20 percent for the higher winds. Naturally, it is unlikely that
May?, 2010 Homestake Mining Company Page 29
-------
the radon daughter equilibrium at the monitoring station at 2,500 feet would reach 20 percent for
winds in this speed range. Therefore, this calculation shows that the assumption of 20 percent
equilibrium is very conservative for the two monitoring stations located near the site perimeter
and nearby population.
Calm winds may allow radon to reach 100 percent equilibrium if the calm persists for periods of
a few hours. This air could then be driven toward the monitoring stations or in any other
direction, depending on the wind direction at the time. The wind rose data indicate calm winds
occur only 0.02 percent of the time and the wind rose data indicate that there would be only a 20
percent chance that the winds would sweep the stale air toward the monitoring stations (and
population) to the southwest. It is therefore justified to ignore the effect of the small periods of
calm winds.
The radon daughter equilibrium will be higher farther from the site, but because of dilution of
radon and daughters with distance, the levels decrease significantly with distance and very
quickly become indistinguishable from background concentrations.
Radon Background Locations - The ACOE suggests that the HMC consider the use of multiple
radon background locations to better represent the distribution of potential radon concentrations.
HMC does not agree that multiple locations are necessary or appropriate to define the
background at HMC#4 and HMC#5, which are representative of the radon exposure to the
nearest neighbors. The distance between HMC#4 and HMC#5 in the east-west direction is not
far compared to the width of the air drainage path from the north-to-northeast direction. Thus,
more than one background location is difficult to justify based on our current understanding of
the air flows under calm conditions.
HMC has, however, recently questioned whether HMC#16 is representative of the true
background for the site and has taken the initiative to establish additional radon monitoring
stations. Air movement toward the site was modeled using an air model that considers
topographic features. Point sources were input into the model were placed at selected locations
and the direction of air flow during calm conditions were assessed. The result is that there are
three principal drainages toward the site in which radon would be transported. The effort
suggests that a more appropriate location would be in the San Mateo drainage closer to the site,
where the confluence of all three drainages occurs under calm wind conditions. The new
monitoring stations are located to capture all or portions of these drainages and should provide
information on which to base an assessment.
It should be noted that HMC's radioactive material license specifies that HMC#16 should be
used as the radon background location for the site. HMC will have to perform this assessment
and present it to the NRC for review, and approval should the assessment justify a change.
May?, 2010 Homestake Mining Company Page 30
-------
Radon Emissions from Evaporation Ponds - During hearings for the renewal of DP-725, Mr.
Gerard Shoeppner of the Mining Compliance Section within the Groundwater Quality Bureau of
the New Mexico Environment Department testified that the majority of radon at the site
originates from the tailings piles and not from the ponds. HMC has recently assessed the radon
emissions from the site, including the evaporation ponds. The major sources of radon releases
are primarily based on measurements, but where measurements are not available, conservative
calculations were made. NRC requires radon flux measurements to be made on the large and
small tailings piles annually following EPA Method 115 procedures. The averaged measured
fluxes and the known areas of the piles were used to estimate the annual releases. The flux from
the evaporation ponds was estimated from a model based on the assumption that the radon was in
secular equilibrium with the dissolved radium-226. In order to validate the model, floating
activated charcoal radon flux canisters were deployed on one of the ponds for 24 hours using
EPA Method 115 analytical procedures. There was good agreement between the modeled results
and measured results (to be published). For releases from the spray system, the annual HMC
reported evaporation rate of 182 gpm (from Ponds 1 and 2 combined) as a result of the spray
systems was used. It was assumed that radon-222 was in secular equilibrium with the measured
radium-226 in the ponds, and that all of the radon in the sprayed water was released to the
atmosphere. The only other radon source that was evaluated was the radon released within the
RO building. In that case, the release was calculated by using the measured radon concentrations
within the building and an assumed air exchange rate of 2 per hour. As can be seen from Table 2,
the evaporation spray system is the least significant source of radon released from the site.
Therefore, HMC believes that we have already addressed the recommendation to assess the
releases from the evaporation ponds.
Table 2. Individual radon sources and annual contribution to total radon source.
Radon Source Percent Contribution
RO Building 0.08
Surface Flux (Evaporation Ponds EP-1 and EP-2) 2.1
Spray System (Evaporation Ponds EP-1 and EP-2) 0.01
Small Tailings Pile 14.0
Large Tailings Pile 83.7
May?, 2010 Homestake Mining Company Page 31
-------
Recommendation No. 14 - Though risks appear minimal with the current irrigation
practice, consider treatment of contaminated irrigation water via ion exchange prior to
application as a means to remove contaminant mass from the environment.
HMC Response:
The irrigation system is an important component of the remedial systems at the Grants site. It
provides an effective means of management of water that is extracted in order to control and
contain the uranium plume, and enables continued progress toward meeting the groundwater
remediation targets. Annual irrigation reports are published and provided to all stakeholders at
the Grants site. These reports detail all aspects of the irrigation program.
HMC has previously evaluated the use of the irrigated areas based on the assumption that the
HMC would make the irrigated areas immediately available to a resident farmer and that the
currently used irrigation water would not be available to the resident farmer. This scenario is
evaluated in the 2009 HMC Irrigation Report. Currently, the water applied to the irrigation areas
is piped into the area rather than taken from beneath the irrigation areas. Therefore, only non-
impacted irrigation water would be applied by the resident farmer.
Currently, the maximum uranium retention in the upper soil surface layers occurs in the Section
34 Flood Irrigation Area, where a buildup of uranium-238 of 0.69 pCi/g has occurred after
approximately 10 years of irrigation. The HMC analysis using RESRAD indicates that the dose
to the resident farmer is less than 0.3 millirems/year, which is insignificant.
ACOE RESRAD analysis - ACOE assumed a resident farmer scenario where uranium-238
accumulated in the top layers of soil was 10 pCi/g. A buildup of 10 pCi/g would only occur,
based on historical data, after approximately 140 years of irrigation at the present rate using
water similar to that which was used over the last 10 years. ACOE's analysis shows that the
aquifer beneath the irrigated area would not be impacted from soils contaminated with uranium-
238 atlO pCi/g. The ACOE calculated a water independent dose of 3.82 millirems, which agrees
with HMC's analysis, if the doses are assumed to scale with the uranium-238 concentration.
The next part of the scenario is highly unlikely because HMC currently owns this property.
ACOE assumed that this resident farmer uses contaminated water to irrigate his crops. The total
uranium concentration is assumed to equal the NRC effluent limit of 0.44 mg/L. Naturally, the
dose from garden vegetables grown under these conditions is relatively high with most of the
dose arising from applying water directly to the garden plants. They estimate that the resident
farmer would incur a dose of 18.2 millirem/year under these unlikely conditions, resulting in an
estimated risk that is slightly above the EPA's desired cancer risk range for reclaimed CERCLA
sites of 10"6 to 10"4 excess cancer risk.
May?, 2010 Homestake Mining Company Page 32
-------
HMC's primary concern with ACOE's analysis is with their scenario. First, HMC would not
release this land for use by a resident farmer until the off-site groundwater restoration was
considered complete. This is expected, however, to occur long before the approximate 140 years
during which the projected uranium buildup in soil would reach 10 pCi/g of uranium-238.
Second, the assumed uranium concentration of 0.44 mg/L is higher than the currently measured
values in the monitoring wells in the area and thus, is unrealistically high. Most of the
monitoring wells within the irrigated areas indicate that the water is below or near the uranium
site standard of 0.16 mg/L.
HMC requests that Table 5 and Table 6 be removed from Section 8.1.1 of the report because
they were generated based on the irrelevant and misleading irrigation scenario as described
above.
Ion Exchange Pre-Treatment - Even though the conclusions of the very conservative RESRAD
modeling indicate that concentrations of uranium (30 mg/kg) accumulated in the soil (under a
conservative scenario) are not a risk, the ACOE recommends that ion exchange technology be
used for the pre-treatment of water used for irrigation in order to remove the uranium. HMC does
not believe this would improve the current irrigation system, and would be technically infeasible
to implement due to the following reasons:
1) Ion exchange technology has been tested and was unsuccessful in the removal of uranium
using an ani on-exchange resin due to the presence of high concentrations of sulfate (-600
mg/L) and fouling of the resins due to calcite precipitation. In addition, the chemical
speciation is non-ideal due to the presence of large molar excess of calcium and
bicarbonate compared to uranium (see point 2, below).
2) The ion exchange technology suggested by ACOE involves products provided by
REMCO Engineering (http://www.remco.com/ixidx.htm). This technology requires that
uranium be present in groundwater in a form suitable for removal on an ion exchange
resin (e.g., uranium must be present as the charged forms: cationic (UO22+) or anionic
(UO2(CO3)22")- Geochemical modeling of the uranium speciation using the average
concentration of species in the Grants site untreated irrigation water (Table 7 of the Draft
RSE Report) as the input file (reproduced here as Table 3), shows that the uranium in the
groundwater is dominated by a neutral form (Ca2UO2(CO3)3)(Figure 7). The neutral form
of uranium would not be amenable to ion exchange, as verified by work conducted by the
U.S. Department of Energy (Dong and Brooks 2006), that showed that uranium sorption
onto anion-exchange resins is inhibited by the formation of the neutral
9-1-
species. Pre-treatment to create acidic conditions (to form UO2 ) would not be efficient
due to the poor selectivity of cation exchange resins and the relatively high concentration
of cations (e.g., Ca2+, Na2+, Mg2+) in the groundwater compared to uranium. Use of a
May 7, 2010 Homestake Mining Company Page 33
-------
cation exchange resin would require frequent backwashing to strip the groundwater
cations and rejuvenate the resin.
Table 3. Average concentration of species in untreated irrigation water.
Constituent
U022+
Ca2+
Mg2+
Na+
K+
cr
so42-
N03-
HCO3"
Se6+
mg/L
0.28
242
65
285
8
180
840
3.5
460
0.06
g/mol
238
40
24
23
39
35
96
62
61
79
mM
0.001
6.05
2.71
12.4
0.21
5.14
8.75
0.06
7.54
0.001
logM
-5.92
-2.22
-2.57
-1.91
-3.69
-2.29
-2.06
-4.25
-2.12
-6.12
3) Even if uranium treatment were feasible, pre-treatment of groundwater prior to ion
exchange treatment would be required to remove sulfate and to remove calcium. At least
two separate pre-treatment resin beds would be required for this, in addition to the resin
required to remove uranium. Regeneration would require 2 to 3 percent of the total
influent volume, using regeneration brines. This would frequently create thousands of
gallons of brine requiring management and disposal. If treatment occurred at a point near
the irrigation, this would require the construction of a treatment plant in order to handle
the resin and to accommodate the stripping operation required once the resin becomes
expended. The concentrated waste material would create a significant management
challenge relative to safety and human health.
May 7, 2010 Homestake Mining Company Page 34
-------
u
-1
-2
-3
+ CM -A
o
io -5
O)
° -6
-7
-8
-9
_
Ru
UO2SO4A3H2O
-
-
-
U02S04UO
-
-
/ ' ' \ -
lerforonne \
/ \
Ca2UO2(CO3)3
a
;o3
-
-
25° C
I I I I
0 2 4 6 8 10 12 14
pH „.,„,„„
Figure 7. Predicted speciation of uranium based on the groundwater chemistry provided in Table 3. The symbol (•)
on the figure shows the pH and uranium concentration relevant to the irrigation water; note that the predominant
form of uranium is the neutral Ca2UO2(CO3)3 aqueous species. Note that the y-axis shows the uranium
concentration.
Summary
The HMC Grants site has experienced significant remediation progress. HMC has aggressively
worked to address the unique remedial issues at the site created by the size of the tailings pile
and the number of aquifers to be addressed. In this connection, HMC has developed creative
solutions to facilitate completion of remedial goals in the shortest possible time. While
remediation has been ongoing for many years, the time involved is not extraordinary compared
to what other complex uranium processing facilities have experienced. HMC's foregoing
comments reflect a concern that the ACOE's evaluation does not reflect a full appreciation of the
complexity of the Grants site, nor does the evaluation provide any innovative or positive
suggestions to enhance the current remedial program. HMC is considering additional remedial
techniques to accelerate remediation at the site and plans to continue its aggressive approach to
finalize site reclamation.
May 7, 2010
Homestake Mining Company
Page 35
-------
References
Bernhard, G., Geipel, G., Reich, T., Brendler, V., Amayri, S., and Nitsche, H. 2001. Uranyl(VI)
carbonate complex formation: Validation of the Ca2UO2(CO3)3(aq) species. Radiochimica
Acta: 89(511-518).
Delaney, J.M., and Lundeen, S.R. 1989. The LLNL Thermochemical Database. Report UCRL-
21658. Lawrence Livermore National Laboratory.
Dong, W., and Brooks, S.C. 2006. Determination of the formation constants of ternary
complexes of uranyl and carbonate with alkaline earth metals (Mg2+, Ca2+, Sr2+, and Ba2+)
using anion exchange method. Environmental Science and Technology 40: 4689-4695.
Homestake Mining Company and Hydro-Engineering, LLC. 2009. 2008 Annual Monitoring
Report/Performance Review for Homestake's Grants Project; Pursuant to NRC License
SUA-1471 and Discharge Plan DP-200; prepared for U.S. Nuclear Regulatory Commission
and New Mexico Environment Department. March.
Nuclear Energy Agency (NEA). 2010. Thermochemical Database Project.
http://www.nea.fr/dbtdb/. Accessed April 4, 2010.
Salhotra, A.M, Adams, E.E., and Harleman, D.E. 1985. Effect of Salinity and Ionic Composition
on Evaporation: Analysis of Dead Sea Evaporation Pans. Water Resources Research, Vol.
21, No. 9, September.
Skiff, K.E., and Turner, J.P. 1981. A Report on Alkaline Carbonate Leaching at the Homestake
Mining Company. Report Prepared for Homestake Mining Company.
U.S. Environmental Protection Agency (EPA). 1998. Evaluation of Subsurface Engineered
Barriers at Waste Sites; Office of Solid Waste and Emergency Response (5102G); EPA 542-
R-98-005; August 1998.
U.S. Environmental Protection Agency (EPA) and U.S. Geological Survey (USGS). 2000. Field
Demonstration of Permeable Reactive Barriers to Remove Dissolved Uranium from
Groundwater, Frye Canyon, Utah, September 1997 through September 1998 Interim Report,
EPA 402-C-00-001, November.
WRT. 2007. Homestake Mines, Grants, NM Phase III pilot testing results and conclusions.
Technical memorandum from Charlie Williams and Scott Hefner.
Zheng, Z.G., Tokunaga, T.K., and Wan, J. 2003. Influence of calcium carbonate on U(VI)
sorptionto soils. Environmental Science and Technology 37: 5603-5608.
May 7, 2010 Homestake Mining Company Page 36
-------
ATTACHMENT A
Inconsistencies and/or Incorrect Statements Identified in the
ACOE Draft RSE Report (February 2010)
Executive Summary; page ii. A conclusion is made that there may have been widespread
impacts on the general water quality (e.g., ions such as sulfate) of the alluvial aquifer since mill
operations began, but the limited amount of historical data precludes certainty in this conclusion.
HMC believes that this conclusion is speculation, and the Grants site does not contribute to
widespread impacts. The ACOE fails to recognize that there are several alluvial systems in the
Grants vicinity. The San Mateo alluvial system underlies the site with contributing water-quality
effects from the Rio San Jose alluvium to the west and the Lobo alluvium to the east. It is,
therefore, the combination of water quality from each of these alluvial systems that may
represent any potential widespread impact, and the Rio San Jose alluvium is known to have
elevated sulfate.
Executive Summary, page ii. A conclusion is made that the seepage modeling likely
overestimates the efficiency of flushing of the tailings. JTMC disagrees with this conclusion. Our
review of the model predictions shows that the model reasonably matches observed conditions
with a lag effect. This lag effect is due to reductions in extraction within the large tailings pile in
recent years that was not envisioned nor included in the modeling effort.
Section 1.1, page 1. A statement is made that leaching from the mill site has contaminated
groundwater. JTMC is unaware of any supporting documentation that the mill site has
contaminated groundwater.
Section 1.4, Condensed Overview of Site; page 3. The previous RSE report is mentioned.
JTMC would like to point out that this previous report was flawed and had errors in its
interpretations.
Section 1.4.3, Contaminants; page 4. A statement is made that '"''Data for samples collected in
the 1950s from a couple of alluvial aquifer wells approximate 2.5 miles west of the site (well
numbers 0935 and 0936) suggest significant increases in sulfate concentrations have occurred''
These wells are in the Rio San Jose alluvium west of and unimpacted by the site. The inference
in this section, however, is that the increasing sulfate in the wells may be due to the Grants site
and it is not. Any observed increase in sulfate would be due to activities further west and
upgradient of the wells.
May?, 2010 Homestake Mining Company Page 1
-------
Section 1.4.4, Extraction and Injection Systems; page 4 The extraction and injection system
is stated to be not well documented. HMC disagrees with this statement. The system is
sufficiently described in the annual groundwater monitoring report, which contains the volumes
of water removed and injected, constituent concentrations of these waters, and maps showing the
locations of system components.
Section 1.4.5, Treatment System; page 5. The RO treatment capacity is stated as 600 gpm and
practical limitations are less than that. This is incorrect. The RO plant can be run at higher rates
and, with the additional capacity provided by the third evaporation pond, can be operated at the
600 gpm rate or higher. The limitation is not in the clarifier section.
Section 1.4.6, Evaporation Ponds; page 5. A discussion of the evaporation ponds is presented,
but is not complete. The ACOE does not mention that pond #2 has a double liner and pond #1
has a single liner. A third evaporation pond that has been approved by the NRC has just received
approval from NMED.
Section 2.1.1, Conditions in the Tailings Piles; page 6 A statement is made that it is possible
the uranium is not as accessible for dissolution, but it may slowly mobilize over time. The ACOE
provided no basis for this statement, and our evaluations do not support it either (See HMC's
response to Recommendation No. 1). This statement should be removed from the final RSE
report.
Section 2.1.3, Evaporation Ponds; page 6. The ponds are stated as being a possible secondary
source of contaminants affecting air, soil, and groundwater if the liners under the ponds were to
leak. This statement is speculative and should be removed from the final RSE report.
Section 2.1.4, Irrigated Acreage; page 6. Irrigation with site water is stated as possibly
affecting groundwater through leaching. This is contrary to the ACOE's finding in the draft RSE
report that irrigation has not impacted groundwater. This statement should be removed from the
final RSE report.
Section 2.2.1, Air; page 7. . It is stated that the air monitoring program at the Grants site
attempts to quantify the radon in air pathway. HMC has actually gone to great lengths to
"quantify" this pathway and has found that the measured radon at the site boundary primarily is
from natural background sources, with only a small component originating from the site.. In
fact, the EPA issued a "no action" on Radon in the Record of Decision for Grants at a point in
time when the tailings piles were open and the mill was still operating. This decision was based
on a comprehensive study where radon concentrations were measured in nearby homes by an
May?, 2010 Homestake Mining Company Page 2
-------
independent competent scientist. The tailings piles are now covered and the mill has been
decommissioned so the on-site source has been greatly reduced
Section 2.3 and Figure 2, Receptors; page 7. The text incorrectly refers to Figure 1 as the
conceptual site model. The conceptual site is shown on Figure 2. HMC believes that the
conceptual site model is flawed. As discussed in our response for Recommendation No. 4, HMC
does not believe that the former mill area is a "Primary Source," as depicted on the conceptual
site model. Additionally, several of the exposure pathways that are indicated as complete are
actually not complete. An example of this is the incomplete groundwater drinking pathway for a
trespasser, resident, or worker, currently and in the future. We suggest that the ACOE re-
examine this conceptual site model before issuing the final RSE report.
Section 3.2, Concentration Trends; page 13. The ACOE cites well 0882, located south of the
wells used for irrigation in the northern plume, as providing evidence for incomplete capture
because uranium concentrations have increased. However, the increase is only on the order of
0.02 mg/L and within typical variability of uranium concentrations in the alluvial aquifer in this
area. The uranium concentration is below the site standard and below the maximum contaminant
level, and the slight increase is not an indicator of incomplete capture.
Section 3.2, Concentration Trends; page 15. Well DD is discussed and the uranium
concentration in the well is speculated to be a result of migration from the tailings pile. Well DD
is an approved background well and the 95 percent confidence limit of uranium concentrations in
the well were used to set the site standard for the alluvial aquifer. It is highly unlikely that
groundwater is flowing to the north because the water level in well DD is several feet higher than
at the tailings pile. Furthermore, the uranium concentration has consistently been near the 0.16
mg/L site standard level since 1995, indicating a steady source of uranium from upgradient areas,
whereas the uranium concentration at the tailings pile has been decreasing over this period. If
the tailings pile was the source of uranium in well DD, one would expect the uranium
concentration to decrease to some degree because of the decreasing concentrations at the tailings
pile, but this has not occurred.
Section 3.4, Ground-Water Modeling; page 15. It is stated that the model likely over-predicts
the performance of tailings flushing. A similar statement is made in the Executive Summary.
HMC's review of the model predictions shows that the model reasonably matches observed
conditions; however, there is a lag effect. This lag effect is due to reductions in extraction within
the large tailings pile in recent years that was not envisioned nor included in the modeling effort.
Section 3.6, Impacts to the San Andres Aquifer; page 16. It is stated that the flow direction in
the San Andres aquifer is to the northeast. However, the flow direction is toward the east and
May?, 2010 Homestake Mining Company Page 3
-------
slightly southeast, as shown on Figure 8.0-1 of the 2008 Annual Monitoring Report (HMC and
Hydro-Engineering, LLC. 2009).
Section 4, Overall Remedial Strategy; page 17. The ACOE states that "According to
Homestake, flushing of the tailings pile will be completed by 2012, with the remaining
groundwater contamination completed by 2017." The last part of the sentence is worded in an
awkward manner; it should read "...with remediation of the remaining groundwater
contamination completed by 2017."
Section 4, Overall Remediation Strategy; page 17. The ACOEs states that "...potentially
applicable replacement technologies are discussed...." Two of the possible strategies, slurry
wall and PRBs are discussed. Each of these technologies is technically impracticable (see
HMC's response to Recommendation No. 8). The ACOE actually provides no replacement
technologies that have not already been considered.
Section 4.1 and Figure 14, Flushing of Large Tailings Pile; page 17. The flushing of the large
tailings pile is discussed and Figure 14 is used to show the 2008 uranium concentrations in the
tailings. Although the ACOE uses this figure to show the variability of uranium in the pile and
illustrate their belief that the flushing has not been effective, HMC believes that the flushing has
been effective at removing uranium mass. This is demonstrated by comparing the 2000 and
2009 maps for uranium in the tailings pile, which shows that a significant amount of uranium has
been removed. See also HMC's response to Recommendation No. 2 for additional evidence of
the effectiveness of the flushing and extraction program. Below is the 2000 uranium
concentration map for the tailings pile showing uranium concentrations exceeding 30 mg/L in
much of the pile. Also below is a map of the 2009 uranium concentrations in the pile, which
illustrates the significant reduction in concentrations resulting from the flushing and extraction
program. For 2009, approximately 67.5 percent of the west side slime area has uranium
concentrations less than 5.0 mg/L, and 45.5 percent of the same area has concentrations lower
than 2.0 mg/L.
May?, 2010 Homestake Mining Company Page 4
-------
TAILINGS URANIUM (mg/l)
2000
TAILINGS URANIUM (mg/l)
2009
Section 4.1, Flushing of Large Tailings Pile, first paragraph; Page 19. The ACOE presents a
calculation of the volume of water within the tailings and bases the volume on a total porosity of
30 percent, which is not substantiated or appropriate. The mobile porosity (i.e., effective
porosity) of the tailings should have been used. The slimes may have a total porosity of around
30 percent, but the effective porosity is more on the order of 8 percent and 14 percent for the
tailing sands. The result of this is that the ACOE has most likely overestimated the volume of
water in the tailings, which correspondingly underestimates the success of the flushing and
extraction system. HMC estimates that approximately one pore volume has been flushed from
the tailings.
Section 4.1, Flushing of Large Tailings Pile, second paragraph; Page 19. A calculation is
made of the natural groundwater flow in the alluvial aquifer beneath the large tailings pile, which
is substantially overestimated. Based on site data, the hydraulic conductivity of the alluvium
used in the calculation should be about 20 feet/day, not 80 feet/day. The gradient of 0.008 is high
May 7, 2010
Homestake Mining Company
Page 5
-------
and should be lower near approximately 0.003. HMC's estimate of the natural flow in the
alluvial aquifer is in the range of 60 to 80 gpm, not 450 gpm as estimated by the ACOE.
Consequently, the amount of alluvial groundwater that needs to be captured beneath or
surrounding the large tailings pile is considerably less than what is estimated by the ACOE.
Section 4.2, Downgradient Extraction and Injection, first paragraph; Pages 19-20. The
ACOE states that injection of relatively clean water from other aquifers into the alluvial aquifer
may do more to dilute the plume than treat it. However, injection of water has demonstrated to
be an effective technology for plume control, and in addition to controlling the plumes, injection
is often necessary to sustain a sufficient saturated thickness in the alluvial aquifer to enable
extraction to occur; otherwise the aquifer would be dry. An example of this is at Felice Acres,
where injection into the alluvial aquifer occurs. Initial extraction wells in this area yielded very
little water and wells commonly became dry when pumped. With injection, a sufficient saturated
thickness is maintained that enables uranium and other constituents to be collected. Without
injection little or no constituent mass would be extracted.
The ACOE also states that extraction from the Upper Chinle draws water downward from the
more contaminated alluvial aquifer. The only area where this could possibly occur is in the
collection pond area where there is an approximate 500-foot wide zone of saturated alluvium
overlying the Upper Chinle Aquifer, and extraction in the Upper Chinle Aquifer occurs in this
area. However, HMC does not believe that pumping from the Upper Chinle Aquifer in this
limited area is drawing contaminants downward as the following explains. The two most
important parameters that control the movement from one aquifer to another are the head in the
driving aquifer and the vertical hydraulic conductivity of the materials that the water has to move
through between the two aquifers. In the collection pond area, the head in the alluvial aquifer
would have to be substantially higher than the head in the Upper Chinle Aquifer and the
materials would have to be highly permeable. Review of the 2008 water levels in the two
aquifers in this area reveals that there is minimal head difference. As shown on the water level
elevation map for the alluvial aquifer (Figure 4.2-1, HMC and Hydro-Engineering, LLC. 2009),
the elevation near the collection pond is typically in the range of 6,525 to 6,530 feet. Water
elevation in Upper Chinle Aquifer (Figure 5.2-1, HMC and Hydro-Engineering, LLC. 2009) is
also interpreted to be in the same elevation range. Water levels in the two aquifers near the
collection pond have not significantly changed since the increased pumping in the Upper Chinle
aquifer started in 2006, which is further evidence that the pumping has not induced downward
flow from the alluvial aquifer.
Section 4.4.3, In-Situ Immobilization; page 27. The ACOE suggests that a relatively new
immobilization technology, still in lab development, be examined. The reference given is to
"Frysell et al., 2005." This citation is incorrect; it should be Fryxell et al., 2005 (as noted
correctly in Section 10, References). The referenced work involves the use of self-assembled
May?, 2010 Homestake Mining Company Page 6
-------
monolayers on mesoporous supports (SAMMS), and as indicated by the ACOE, this is
experimental and currently confined to the laboratory bench.
Section 5.3, Alternatives to Current Treatment Operation; page 30 The ACOE states that
ion exchange resin cannot reliably remove the cation form of selenium, selenite. Selenium will
not be present as a cation in the groundwater. Selenium typically is found as selenate (SeO42~;
with selenium in the +6 oxidation state) or selinite (HSeOs" or SeOs2"; with selenium in the +4
oxidation state) depending upon pH. All of these forms of selenium are anionic.
Section 6.2, Effect of Salinity; page 32. An evaporation rate reduction of 50 percent in the
ponds is cited. However, HMC's research has found that the reduction rate is lower at
approximately 10 percent (Salhotra et al. 1985) for the salinity present in the evaporation ponds.
Section 7.2.4, Sampling Methodology and Analytical Suite; page 38 The ACOE provides
details of improvements to the presentation of data in the air paniculate laboratory reports. HMC
has followed the standard reporting format required by NRC for the laboratory reports.
Section 9.3, Approach to Implementation of Recommendations, second paragraph; page
47. The ACOE provides a list of six recommendations that should proceed independent of any
other recommendations. HMC's view on each of these recommendations and how to proceed are
discussed in our responses as identified below:
1) the evaluation of the potential escape of contaminants at the northwestern portion of the
site (see Response to Recommendation No. 3)
2) the evaluation of the former mill site as a potential source of groundwater contamination
(see Response to Recommendation No. 4)
3) further characterization of the extent and migration of the Chinle plumes (see Response
to Recommendation No. 5)
4) complete decommissioning of potentially compromised San Andres wells (see Response
to Recommendation No. 7)
5) development of a comprehensive optimized monitoring program (see Response to
Recommendation No. 12)
6) implement treatment of contaminated irrigation water to remove contaminant mass from
the environment (see Response to Recommendation No. 14)
May?, 2010 Homestake Mining Company Page 7
-------
ATTACHMENT B - Wind Rose
WIND ROSE PLOT:
Homestake Meterology Station
Wind Rose
DISPLAY:
Presented in a circular format, the wind rose shows the frequency of winds
blowing from particular directions over a period of time. The length of each
"spoke" around the circle is related to the frequency that the wind blows
from a particular direction per unit time. Each concentric represents a
different frequency, emanation from 0% at the center and increasing to 10%
at the outer circle.
DATA PERIOD:
00:00 September 1,
2008 to 23:00 August
31, 2609
CALM WINDS:
0.02%
AVG. WIND SPEED:
3.49 mis
COMPANY NAME:
TOTAL COUNT:
8765 hrs.
DATE:
9/29/2009
PROJECT NO.:
WRPLOTView- Lakes Environmental Software
May 7, 2010
Homestake Mining Company
Page 1
-------
BILL RICHARDSON
Governor
DIANE DENISH
Lieutenant Governor
NEW MEXICO
ENVIRONMENT DEPARTMENT
Ground Water Quality Bureau
1190 St. Francis Drive, P. O. Box 5469
Santa Fe.NM 87502
Phone (505) 827-2900 Fax (505) 827-2965
www.mnenv.state.nm.us
RON CURRY
Secretary
SARACOTTKELL
Deputy Secretary
April 19, 2010
Ms. Kathy Yager
U.S. Environmental Protection Agency
Technology Innovation and Field Sen/ices Division
11 Technology Drive (ECA/OEME)
North Cheimsford, MA 01863
RE: Comments from the New Mexico Environment Department on DRAFT REPORT "Focused review
of specific remediation issues; an addendum to the Remediation System Evaluation for the
Homestake Mining Company (Grants) Superfund Site, New Mexico" (U.S. Army Corps of
Engineers, February 2010)
The New Mexico Environment Department Ground Water Quality Bureau ("NMED") has reviewed the
above-referenced report, and generally finds it to be a very thorough and comprehensive evaluation of
the operating remedial systems operational at this Site. NMED appreciates the amount of effort reflected
in this draft, and submits the following comments for consideration in the final draft:
Specific comments
Section no.
1.1.2
1.4,3
1.4.6
2.1.2
2.1.3
2.2
Comment
Assessment of the adequacy of the Site monitoring network (Bullet #5) should also
include evaluation of wells to monitor the delineation between saturated and
unsaturated conditions in the alluvium, with emphasis on the potential for
contaminants to migrate from the southernmost alluvial contaminant plume without
detection.
Site contaminants of concern for which ground water remedial goals have been
established Include nitrate, chloride, and vanadium. NMED notes that interpretation
of nitrate data may be complicated by agricultural activities that occurred prior to
and during legacy uranium activities in the area.
The second to the last sentence in the first paragraph compares alluvial ground
water data from 2.5 miles west of the site to alluvial ground water data at the site to
demonstrate degradation of water quality. This is not an appropriate comparison as
the alluvial ground water data taken west of the site is representative of San Jose
alluvial water, whereas the data for the site is San Mateo alluvial ground water.
The first sentence in the second paragraph should read 'Water within the tailings
piles..."
Note that EP-2 construction Included a double liner with leak detection.
Another possible explanation for elevated contaminant concentrations in the "1"
series wells could be the result of a concentration gradient.
Please qualitatively evaluate potential ecological risks from the use of uncovered
evaporation and collection ponds.
Although the surface water pathway is not complete, periodic flooding due to heavy
rainfall does occur. Furthermore, one conclusion In this report is that contaminant-
-------
Ms. Kathy Yager, EPA
RE: Comments from the New Mexico Environment Department on DRAFT REPORT "Focused review
of specific remediation issues; an addendum to the Remediation System Evaluation for the
Homestake Mining Company (Grants) Superfund Site, New Mexico" (U.S. Army Corps of
Engineers, February 2010)
April 19, 2010
Section no.
2.2.3
2.3
3.2
3.6
4.1
4.2
Comment
source waste materials (i.e., the tailing piles) should remain on-site. Therefore,
NMED herein reiterates an earlier comment from the discussion of the scope of
work for this study that review of flood control structure constructed for the long-
term protection of the tailings piles must be included within the RSE.
Although alternative water sources (i.e., hookups to the Milan municipal water
supply) have been offered to current residents within an Area of Concern, which
NMED has defined based upon the surface areal extent of Site-derived historical
ground water contaminant plumes, there are currently no mechanisms either to
require such hookup for current or future residents, nor to preclude the use and
installation of private wells within this area. Additionally, current monitoring for
potential Site-derived impacts to the San Andres aquifer is inadequate to document
long-term protection of this aquifer. For these reasons, NMED does not agree with
the assertion that the ground water pathway is incomptete.
The last sentence should refer to Figure 2 instead of Figure 1 .
Please move x-axis label to bottom of figures 3, 4, and 8.
The San Andres aquifer is an important municipal water supply source to the
nearby major population centers of Grants, Milan, and Bluewater, as well as to
residents using private wells within the impacted subdivisions south of the Site.
NMED asserts that routine and focused monitoring of this aquifer, both upgradient
and downgradient of the Site, should be included within the Remedial System to
better support an assertion of no contaminant impacts to this aquifer from the
overlying Site-contaminated aquifers.
The RSE team's argument for the discontinuation of the Large Tailings Pile ("LTP")
flushing appears to be incomplete. NMED suggests that trends of contaminant
concentrations in effluent discharged to the collection ponds should be evaluated
and cited. Additionally, the heterogeneity of the LTP materials could indicate that
some portion of uranium concentrations that do not respond to flushing (e.g.,
contaminants within slimes and other fine-grained materials) mostly will remain in-
situ, and, therefore, may not significantly impact alluvial ground water quality after
flushing of the more-accessible and mobile contaminant concentrations within the
LTP meets the flushing effluent objective. The RSE team might consider whether
1} continued flushing with reducing and/or low-alkalinity solutions to "fix" remaining
accessible contaminants in-situ, and/or 2) deployment of either an impermeable or
an evaporative cover to the LTP, could reduce additional contaminant leaching from
the LTP once draindown is complete.
"Tailings" in Figure 15 is misspelled.
The RSE team did not document evaluation of possible alternatives to flushing of
the LTP. Please provide an evaluation of possible alternative actions, including a
comparative analysis of pump-and-treat at the toe of the LTP during draindown, in-
situ immobilization technologies, and any other applicable alternatives.
The second sentence in the second paragraph on page 19 should acknowledge
that draindown of the LTP may take decades.
The last paragraph appears to assume a trend of decreasing contaminant
concentrations after LTP flushing is discontinued. While flow rates would likely
decrease over time due to termination of flushing, the RSE should address the
possibility that contaminant concentrations In ground water may increase.
The last sentence of the first paragraph on page 20 recommends injection of fresh
water into the Chinle to reverse the recharge (contamination) from the alluvium to
the Upper Chinle. NMED recommends that the RSE team evaluate the possibility
Page 2 of 4
-------
Ms. Kathy Yager, EPA
RE; Comments from the New Mexico Environment Department on DRAFT REPORT "Focused review
of specific remediation issues; an addendum to the Remediation System Evaluation for the
Homestake Mining Company (Grants) Superfund Site, New Mexico" (U.S. Army Corps of
Engineers, February 2010)
April 19, 2010
Section no.
4.3
4.4.1
4.4.3
4.4.4
6.3
7.1.1
7.1.2
8.1.1
8.2
Comment
that this action may exacerbate migration of contamination in the Upper Chinie.
The reliance on "existing liner (sic} under pond wastes" for long-term waste isolation
may be inappropriate due to the observed and presumed deterioration of these
mostly single liners over the ponds' usage period. Additionally, NMED recommends
that the RSE team define the term "highly effective cap" within the context of long-
term waste isolation.
No alternative methods of evaluation were discussed to determine if ponds were
leaking other than investigative methods.
The proposal for deployment of slurry wails does not address the long-term
objective to achieve ground water protection standards through establishment of
stable, self-sustaining Site conditions without ongoing maintenance requirements.
NMED recommends that the RSE team attempt to quantify the length of time and
associated costs for such maintenance as would be required under this proposal, in
the same manner that the proposal for permeable reactive barrier emplacement is
evaluated in the section following the discussion of this option in the report.
As noted above, the RSE team might evaluate whether in-situ immobilization
technology could be appropriate to LTP flushing.
For consistency, the RSE team should employ similar AFCEE Sustainable
Remediation Tool analysis of other proposed remedial options.
The original RSE report identified persistent operation and maintenance issues
affecting the operation and maintenance of the evaporative sprayers. NMED
recommends that the RSE team examine whether any different equipment and/or
deployment strategies are available that could address these issues to enhance
evaporation.
The last paragraph states 1 80 gpm as the proposed flow of wastewater into the
evaporation ponds for disposal. This flow assumes the LTP flushing program is
discontinued, but does not account for flows from the toe drain collection wells.
Documentation of the protection of the San Andres aquifer from impacts derived
from the overlying contaminated aquifers should be an important component of the
overall monitoring strategy for the Site.
An important component of a critical re-evaluation of Homestake's monitoring
system should be appraisal of each monitor well's completion documentation and
current condition to ensure that samples from each well accurately reflect the
ground water quality within the aquifer that is presumed to be monitored.
Additional monitoring wells located at the confluence of the San Mateo and Rio San
Jose alluvial systems to monitor the stability of ground water conditions within the
alluvial aquifer should be considered.
The RESRAD modeling should be updated with current data which indicates
contaminants have migrated in the irrigated soils well beyond 1 meter vertically.
It must be noted that the New Mexico Water Quality Control ground water standard
for selenium is 0.05 mg/l, not 0.12 mg/l.
Page 3 of 4
-------
Ms. Kathy Yager, EPA
RE: Comments from the New Mexico Environment Department on DRAFT REPORT "Focused review
of specific remediation issues; an addendum to the Remediation System Evaluation for the
Homestake Mining Company (Grants) Superfund Site, New Mexico" (U.S. Army Corps of
Engineers, February 2010)
Apriim 2010
Please contact either David L. Mayerson at (505) 476-3777 or Jerry Schoeppner at (505) 827-0652 if you
should need clarification on any of these comments.
layerson
Superfund Oversight Section
my Schoeppner
Mining and Environmental Compliance Section
Ground Water Quality Bureau
New Mexico Environment Department
Copies;
Mr. Sairam Appaji, EPA
NMED/GWQB/SOS April 2010 read file
HMC 2010 correspondence file (SOS)
Page 4 of 4
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
May 10, 2010
MEMORANDUM
SUBJECT:
FROM:
TO:
Review of Draft Focused Review of Specific Remediation Issues, An Addendum
to the Remediation System Evaluation for the Homestake Mining Company
(Grants) Superfund Site, New Mexico" (February 2010)
Robert Ford, Ph.D., Research Environmental Scientist
Land Remediation and Pollution Control Division
Kathleen Yager, Environmental Engineer
Office of Superfund Remediation and Technology Innovation
Sai Appaji, Environmental Scientist
EPA Region 6, Superfund Division
Mr. David Becker, Geologist
USACE EM CX
We have reviewed the draft "Focused Review of Specific Remediation Issues, An
Addendum to the Remediation System Evaluation for the Homestake Mining Company (Grants)
Superfund Site, New Mexico" (February 2010). Our comments are provided below.
General Comments
1. Considering the scope of work, time and budget constraints, the USACE has done a
commendable job in evaluating this complex site and provided some practical recommendations.
2. The report is well written and addresses the issues at length that were important to the
stakeholders.
3. The graphs in the report should be reformatted, especially the x and y axis descriptions to
better illustrate the data trends.
Include additional figures wherever possible to show location of wells for better understanding
of the remedial system.
Specific Comments
1. Section 3.4 Ground-Water Modeling, Pages 15-16:
I agree with concern about the modeling approach for projecting uranium (and other
contaminant) concentrations in the Large Tailings Pile (LTP) water under the currently
- 1 -
-------
implemented and projected flushing strategy. While the heterogeneity in the distribution of
flushing efficiency throughout the LTP is a concern, assumption that there are no interactions
leading to contaminant mass exchange between tailings solids and water represents an equal
concern. This assumption currently drives the projection of a stable uranium concentration
starting in 2012, which is the planned date for cessation of clean water injection into the LTP
(see Figure 1 and detail for uranium in Figure 2). Continued injection of water into the LTP
sustains and enhances the hydraulic gradient for contaminant releases into the underlying and
downgradient alluvium. Exposure of tailings solids to this continuing input of water also
provides the conditions for release of previously undissolved contaminants, as has been observed
at other sites where uranium residuals in contaminated soils serve as a source of long-term
contaminant release into groundwater [examples include: Monticello Mill Tailings Site Operable
Unit III (EPA ID#UT3 89009003 5); Hanford 300-FF-l Operable Unit (EPA
ID#WA2890090077].
In line with the recommendation to curtail the current flushing operation, I recommend
implementing a pilot test prior to 2012 to examine the potential for contaminant concentration
rebound as a result of the cessation of flushing. This represents a current data gap in the
conceptual understanding of the ability to achieve and sustain the projected target
concentration(s) for contaminants in the LTP seepage. The results from this field test can
provide valuable information relative to evaluating the potential long-term performance of the
current remediation strategy. Extraction and downgradient injection operations could continue
as present in order to exert hydraulic control on contaminant plume(s) during the pilot study. It
is recommended that a technical discussion occur between all parties involved in site restoration,
management, and oversight, given the observed disparity between remedial design model
projections and historical site-specific monitoring data (see Figure 2 for uranium).
2. Section 4.2 Downgradient Extraction and Injection, Page 20:
The following statement is made within the report text: "Contamination downgradient of
these points would be allowed to naturally attenuate due to dispersion. Based on the presumed
oxidized condition and low organic carbon content of the alluvial aquifer, other attenuation
processes are unlikely to be significant." With regard to aquifer solids, clays and oxyhydroxide
minerals are commonly the primary solid components to which metals and radionuclides will
partition within the alluvium. Existing information on sorption characteristics of the impacted
alluvium may be available through analysis of information presented in ATTACHMENT A -
ALLUVIAL AQUIFER RETARDATION AND DISPERSION TEST RESULTS (GROUND-
WATER MODELING FOR HOMESTAKE'S GRANTS PROJECT, Hydro-Engineering,
L.L.C., April 2006).
3. Section 7.1.4 Sampling Methodology and Analytical Suite:
I recommend caution with regard to the suggestion of "no-purge sampling" as an option
for metals/radionuclides sampling from the HMC network of wells. If this recommendation is
pursued, I recommend that a comparison of analytical data first be conducted for a subset of site
wells prior to switching to this type of a sampling device.
Purging or pumping from the well screen is applied to help insure that the water being
sampled is from the surrounding formation versus storage within the well casing. The
comparability between purge and no-purge sampling techniques will depend on the degree to
which formation water naturally exchanges through the well screen/casing. One specific problem
-2-
-------
I would anticipate for collection of metals/radionuclides samples is the accumulation of mineral
precipitates within the well casing that may be dislodged and entrained within the sampler. For
example, this is a common problem for well screens completed in aquifers with high ferrous iron
concentrations and periodic intrusions of oxygen either from water table fluctuations or gas
exchange from air in the well casing. One diagnostic to determine if this condition exists for well
screens at the HMC Site is to periodically pull up and examine dedicated sampling devices, e.g.,
flexible polyethylene/teflon tubing or in -well pumps. If there are precipitate coatings on the
device at the depth of the well screen, then I would be cautious about using a no-purge sampling
device. These coatings are a common source of elevated turbidity at the initiation of low -flow,
low-stress sampling, but these newly suspended solids are quickly eliminated near the beginning
of the purging process as they are flushed from the well casing. These coatings are also strong
sorbents for many of the TAL metals and can bias analytical data, especially for unfiltered
samples.
The most comprehensive source of information on the benefits and limitations of these
sampling approaches is posted at the Interstate Technology and Regulatory Council website:
http://www.itrcweb.org/guidancedocument.asp?TID=12. (Look at documents DSP-4 and DSP-
5; note that the Snap Sampler collects a grab sample versus relying on diffusion across a
membrane.)
-------
Figure 1. Time trend in average groundwater constituent concentrations for LTP seepage
("Tails" and "Toe" data in Table 2.1-1; 2009 ANNUAL MONITORING REPORT /
PERFORMANCE REVIEW, March 2010), alluvial groundwater ("G.W." in Table 2.1-1), and
projection of restoration performance for LTP injection-collection system (Seepage Model,
"Reformulated Mixing Model Flushing Case F"). Tailings seepage model uranium concentration
projection is documented in GROUND-WATER MODELING FOR HOMESTAKE'S GRANTS
PROJECT, Hydro-Engineering, L.L.C., April 2006 (Table 1-4); proposed cessation of water
injection in LTP provided on page ES-3 of cited report.
12000-
10000-
,-v 8000 -
"g 6000 -
X 4000 -
w 2000 -
0-
70
60
50
_j 4U-
E 30
D 20-
10
o
4-
Q" 3-
~O)
-§ 2-
CO ! J
0-
*,
C
4
A A A A
L
*AA
i
^
\
•".
:«.:.
)
A
i. A
*AA A
kA ^
A ^
T
r
T
C
1
'••..i
i i i i
L
A A
^i'"
A\* A
i.^ . ^•-A^
A A . ->
T
^ ^
:
i
• • " i
"s,
• Avg. "G.W."
• Avg. "Tails"
• Avg. "Toe"
f
1 * • * *
>•••*
i i i 1 i i i i || i
A A
A A
A A
—A— 1
T
AAAA
i A^
^^'*^i~J
*
vg. "G.W."
vg. "Tails"
vg. "Toe"
ailings Seepage Model, Case F
arget Seepage U Cone.
Propose
water in
d cessation of
ection in LTP.
1 1
"
k.""^^~A..-A-.A.~^..A~^
11
y Avg. "G.W."
Y Avg. "Tails"
^ Avg. "Toe"
r
T
r^v3?
7 V V v V
• Avg. "G.W."
• Avg. "Tails"
• Avg. "Toe"
1 m ™
-120
-90 ^
o
-60 ^
-30 ^
-0
1990 1995 2000 2005
Year
2010
2015
-4-
-------
Figure 2. Years 1992-2009 time trend in average uranium concentration for LTP seepage (Table 2.1-1, 2009 ANNUAL
MONITORING REPORT / PERFORMANCE REVIEW, March 2010), alluvial groundwater (Table 2.1-1), and projection of
restoration performance for LTP injection-collection system (Seepage Model, "Reformulated Mixing Model Flushing Case F").
Tailings seepage model uranium concentration projection is documented in GROUND-WATER MODELING FOR HOMESTAKE'S
GRANTS PROJECT, Hydro-Engineering, L.L.C., April 2006 (Table 1-4); projected times [labeled with open, black triangles (V)] for
cessation of LTP injection, LTP dewatering, and alluvial groundwater injection-collection provided on page ES-3 of cited report.
100-
O)
E
2
:D
L
Divergence of seepage model projection from field data for average tailings concentration.
Start of alluvial GW trending higher than
model projection for seepage concentration.
"Restructured Mixing Model" calibration period
LTP Dewatering End
Alluvial GWInjection-
V Collection End
1990
1995
2000
2005
Year
2010
2015
Average "Tails"
Average (Alluvial) "G.W."
—A- Tailings Seepage Model, Reformulated Mixing Case F
-- Target Seepage Uranium Cone.
-5-
-------
4. page i through iv. Be consistent with the use of periods at the end of bulleted sentences/phases. Some sentences/phases have
periods while other do not
5. page i, first bullet. Add "with the current remedial strategy" to the end of the sentence
6. page I, 3rd paragraph, sentence beginning with "The analysis...". Change "at the USAGE EM CX" to "by the USAGE EM CX".
7. pages v through vii. Be sure to align page numbers to the right. Currently numbers are scattered across pages.
8. page 2., Substitute "Robert Ford" for "Michele Simon". Michelle is no longer involved in the project.
9. page 7, section 2.2.1, first sentence. Change'human'to humans"
10. page 7, section 2.2.2, first sentence. Change'and'to'can'.
11. page 9, Figure 1. Add a figure that clearly indicates monitoring well locations. I can not identify monitoring wells referenced in
the report on this figure.
12. page 11 Figures, and Figure throughout document. Please check the labels on the x and y axes - the dates and other units are not
correctly located or easy to read. Please reformat figures to allow for accurate reading of the x and y values.
13. page 17, last paragraph, 3rd sentence. Change 'has' to 'have' and change figure to "Figure 15 in the same sentence.
14. page 18,. paragraph in the middle of the page regarding additional testing of oxidation-reduction potential. Please elaborate on
the types of add'l testing that would be necessary and how the data should be interpreted.
15. page 19, 2nd paragraph. Please clarify the "average saturated thickness" mentioned regarding the calculation of natural flow.
Please include the thickness of the various aquifers at least by reference.
16. page 20, 2nd paragraph. Please add information regarding how the boundary for active pumping vs. natural attenuation should be
determined. Please discuss the need to use modeling or other lines of evidence to help quantify this boundary. Currently, the
statement regarding use of the current extraction wells as the cut off point between capture and natural attenuation seems arbitrary.
17. page 20, 3rd paragraph. Please elaborate on the types of additional study required to assess unusual water levels.
18. page 21, 1st paragraph. Has it been confirmed that the 100 foot error in the C series wells is in fact in error or are you assuming
that it is an error?
19. page 23, 1st paragraph. Double periods at the end of the paragraph.
20. page 23, 2nd paragraph. Double periods at the end of the first sentence.
21. page 23, Table 1. Please create table with gridlines and align numerical values left or right. Currently I believe they are centered
and it is awkward to read. - same goes for Table 2 on page 25.
22. page 23. In the recommendation on slurry wall construction, USAGE should consider deleting the last sentence "The decision for
implementing such an alternative would depend on the economics of the situation" or adding additional clarification. It is not clear
why only this alternative would depend on the economics and not the others.
23. page 27, regarding the recommendation of relocation of the tailings the USAGE should consider evaluating additional potential
hazards from moving the tailings pile besides the CO2 emissions and fatalities. Are there other practical risks from moving the pile?
Other
-------
Please update the last statement on page 5 regarding the approval of the new evaporation pond on the north side of the LTP. NMED
has recently approved the discharge permit for the new evaporation pond.
-7-
-------
NRC Comments on Draft RSE Report
General Comment
The scope of work states, "In general, the review is intended to provide a critical review of the
current remedial ground water strategy, including whether other approaches or technologies
could be incorporated that may be more efficient and/or effective at achieving site closure goals.
The outcome will be a summary of any recommended modifications necessary to improve
performance or overcome performance deficiencies, or that would potentially reduce life-cycle
costs or time to achievement of remedial goals."
In general, the draft report appears not to provide a strong basis for decision-making because of
limitations in the analysis and because it does not compare current remediation strategies to
those that are recommended. As a result it lacks the information necessary to show how the
revised strategy will be more efficient and/or effective at achieving site closure goals.
Specific Comments
1. Technical conclusions made in the report are routinely qualified with "may be", "it
appears", or "likely" which detracts from the usefulness of the document because it
introduces uncertainty about the effectiveness of the proposed remedies due to a lack of
data, or a lack of time to fully assess the hydrologic system. Pursuing changes to the
current remedial strategy with this level of uncertainty seems unwarranted. Specific
comments supporting this conclusion are provided below.
a. Section 2 - Conceptual Site Model
Section 2.1.2 identifies the location of the former mill buildings as a potential
source of contamination to the ground water. However, there is very little basis
provided for such a conclusion. This section states there is "some suggestion"
in ground water monitoring data for this conclusion. It goes on to say that the
elevated uranium levels in the 1 series wells have been observed but that the
"nature of the source is unclear."
b. Section 3.1 - Hydraulic Capture
Section 3.1 states, "Capture is not apparent for the irrigation pumping in the
downgradient portions of the uranium and selenium plumes, nor is it clear from
available data that capture of the plume along Highway 605 east of the site is
maintained." Based on this statement, the reviewers should not draw any
conclusion about the adequacy of plume capture.
c. Section 3.4 - Ground-Water Modeling
The report states, "The primary concern with the modeling conducted for the site
is the simulation of the seepage of contaminated water from the large tailings
pile. From the available information on this step in the modeling process, it
Enclosure
-------
appears the modeling did not account for the likely heterogeneity and preferred
pathways for water injected into the tailings. It seems likely that the
flux of water is not uniform through the pile and that large volumes of the pile still
have a significant amount of their original pore fluids. The model likely over-
predicts the performance of tailings flushing."
d. Section 4.1 - Flushing of large Tailings Pile
o "..heterogeneity of the materials has likely prevented.."
o "..makes it difficult to assess.."
o "It is not obvious the flushing program would meets its goal by 2012.."
e. Section 4.4.1 - Slurry Wall
"This would potentially reduce the long-term costs for the operations, possibly
significantly."
f. Section 7.1.4 - Sampling Methodology
"The use of no-purge sampling techniques, such as Hydrasleeves and Snap
samplers may be considered to reduce the time necessary to sample the
wells." The use of no-purge sampling was not determined to be a time saving or
cost savings alternative to the current sampling methodology utilized by
Homestake.
g. Section 7.2.2 - Monitoring Network
"The number and location of control monitoring stations may not be adequate to
meet the overall objective of ensuring compliance with the public dose limit in
10 CFR 20.1301."
Given that the NRC staff has previously determined that the number and location
of control monitoring stations is adequate, the reviewer should provide additional
justification for its statement.
2. Section 4.2 Downgradient Extraction and Injection
The NRC staff does not agree with the statement,"... injection of relatively clean water
from other aquifers into the alluvial aquifer downgradient of the site at rates that exceed
extraction complicates the control of the plumes and may do more to dilute the plume
rather than treat it." We believe injection is necessary because the hydraulic control
cannot be maintained in the unconfined alluvial aquifer by extraction alone. The number
of extraction wells and their pumping rates would have to be increased to maintain
hydraulic control to an area of this size.
USAGE should re-evaluate the recommendations in this section.
3. Section 7.1.5 - Further Optimization Opportunities
-------
Optimization tools mentioned in this section should have been used for this evaluation
for a limited data set, at minimum, to provide a basis for recommended changes to the
groundwater and air monitoring programs.
4. Section 7.2.2, refers to the "large area potentially impacted by the Homestake effluent
releases". The report should specify what area is impacted by the Homestake tailing
piles radon releases. The Shearer and Sill surveys (Health Physics, 17 (1), pp. 77-88) of
radon-222 concentrations in the vicinity of uranium mill tailing piles, appear to conclude
that no statistically significant difference between measured radon-222 concentrations
around tailing piles and background radon-222 levels could be discerned beyond a mile
from the tailing piles.
The methods in US NRC Regulatory Guide 8.30 for radon-222 daughter measurements
are better suited for assessment of worker's exposure to radon daughters indoors, and
most of these methods may not be appropriate for determining either outdoor radon
progeny levels or an equilibrium factor. The determination of a radon background level
and an appropriate radon & radon progeny equilibrium factor are especially important
and challenging to determine.
5. Section 8.0 - Although efforts were made to take a conservative approach to modeling
this site, RESRAD was not designed to be used to evaluate doses from contaminated
irrigation water. There are other computer codes (e.g., GENII) that can be used to
evaluate doses associated with irrigation. Other options, such as the Radium
Benchmark Dose, which is discussed in 40 CFR 192 and 10 CFR 40, Appendix A,
Criterion 6(6) could also be used.
Some RESRAD parameter values may impact the dose received by the future resident
such as the use of 400 acres (1.6E+6 m2) of soil irrigated with contaminated irrigation
water. It is unlikely that a single individual would be exposed to the entire area while
living on the site. Consideration of soil dilution associated with the construction of a
house with a basement can further decrease the amount of contaminated soil a future
resident may be exposed while the increase in time spent outside from 25% to 50% of
the future resident's time may increase the dose. When evaluating the dose to a future
resident it is also important to include all relevant exposure pathways (e.g., external
exposure, inhalation, ingestion, and radon) associated with the site.
6. Section 8.2.1 - There is no basis for applying the New Mexico water quality standards for
irrigation water. Removal of contaminants prior to irrigation would defeat the purpose of
this remediation strategy. In addition, this section implies that the current practice of
directly applying untreated extracted groundwater for irrigation is done with effluent
concentrations above discharge standards. Groundwater used for irrigation has been
below the discharge standards required by Homestake's license, which is based on 10
CFR 20, Appendix B, Table 2 values.
7. Section 8.2.2 indicates that uranium leaching into groundwater is not considered to be a
likely risk. If the risk is small, and Homestake is meeting its regulatory requirements,
-------
how will the suggestions offered to reduce uranium mobility in the irrigated soil make the
current decommissioning strategy more efficient and/or effective at achieving site
closure goals?
8. Section 9 - Summary of Conclusions and Recommendations
Bullet number 1 of Section 9.1 states that ground water remediation is very unlikely to be
achieved by 2017. The basis for this statement is unclear since the RSE addendum did not
determine an estimated remediation date for the current remediation strategy nor did it provide
an estimated remediation date for the implementation of the recommended changes.
-------
OBSERVATIONS AND
DRAFT FOCUSED REVIEW OF SPECIFIC ISSUES FOR THE
HOMESTAKE MINING COMPANY (Gfllfinsf g||*HRFUND SITE,
February 2010
GROUNDWATER CONSIDERAnONS
Prepared by Milton Head
Member, Bluewater Valley Downstream Alliance
May 11, 2010
A. Stop flushing the Large Tailings Pile.
B. The injection and collection system is extracting a very very small part of the total
contaminants. From 1977 to 1990 data shows there was no extraction of contaminants. The
water collected was returned to the Large Tailings Pile. Since 1990 to 2010, approximately 210
gpm of contaminated water is being collected and stored apparently into one of the three
evaporation ponds. The contaminants are being diluted not extracted. If Homestake/BG is
allowed to drill the 39 new wells, they will be pumping 3,642 gpm while only 210 gpm is being
treated, then only ,0577% of water pumped out of the ground is being treated by extraction.
This current method of remediation of H/BG site and surrounding area will cause a 4,500 to
8,000 acres tailings pile to the created.
C, There must be monitor wells drilled below the original mill site and water tested.
D. Middle CMnle - Based on data from February 2, 1960 to May 1978, of 73 monitoring points,
32 have tds data. The average tds was 1 149. (See Milton Head Exhibit I attached).
E. Use USGS resistivity flights to identify all aquifers. (See Milton Head Exhibit H attached).
F. There is data on San Andres wells. History of San Andres shows many San Andres wells are
showing increase in tds and uranium. (See Milton Head Exhibit TTT attached).
G There is data available concerning upgradient water. There was testing done as early as
1962.(See Milton Head Exhibit IV attached).
H. Construct EP3 and put anything left over from RO extraction into EP3. The addition of
EP3 should eliminate the need for spraying contaminants into the air and spreading them
around the area.
I. There should be no expansion of small tailings pond near the existing STP. Put EP3 into
operation.
J. A slurry wall can be used to isolate the LTP and STP. The technology is available. There
would have to be a study to include concept, engineering, feasibility and cost This does not
preclude the need to move the LTP and STP. These piles can be moved through a slurry pipe,
dried down and placed in a shale or clay geological formation with no risk to community or
public. Moving the tailings piles is no more of a threat to the public health than any operating
-------
uranium mill tailings. The only hindrance is the decision to move them and the money needed
However, slurrying the pile to safe permanent storage minimizes the potential for pollution as a
result of the move and risk to workers.
K. Develop a comprehensive, regular and objectives-based monitoring program.
L. Allow irrigation rather than injection wells. This will allow observation of the success of
extraction methods.
M. H/BG quotes large number of pounds of uranium and other constituents being removed
from the ground waters - locate and identify these constituents. There should be a regular
semi-annual analysis of the water and solids in the existing evaporative ponds.
Well X- dilution is not clean up so quit playing games with Well X.
Leaving uranium in an unlined tailings pile with as much water as the LTP has means it will
continue to seep into our water forever even with a cover.
-------
?•.
:K^^ domestic water
^ 196°>
I" understand
'^^•^^^;^$^^::^-0^^^^ wl* data-
'" ''Y:"'..'' .'•"'t-'^'i''.;"''.'..-'-i !! '.'••' •?-'c/"-Wv"S?i'''?.S"J-;K^1?'f"> '"*".*' .• ' '.-
^^^^f^'-^^^§l^^^i^^A^\^
'^^^^$Xi^^K^!.{:'' "''"'' -
ifW of TTi^ANACONDA Company
-------
ANALYSIS
Murray #1 12.10.34.224
DATE
ANALYST
Gl
ppm-
SOj,
ppm-
-N03
ppm
Cond .
ppm:
HC03
ppm
ppm
Na
ppm
ppra
Ca
ppm
Mn
pern
! "
A
a*L
f9&9
7
•8-A
1170
"
7:0-00
/£>
370
ss-s
IS
v;
J,,L
S-" i.
/52o
.(0 -
/J«|
tie
7970
-ii-
8.3
/ssa
#•7
/3
wo
:'" ,*;V !;:':-.5' ,i~ - \':. ife:;:->y?>£ : .V: r>
'*']j$.'"-1. 'j^'^^r'' J^*SP'^^P^: ^^Sfrfe^SJ
^fiS?^^;*^^
!:'" f1"
-------
WATiiH
ANALYST
ten
***
«Si jvySS-pjf7 -;.
•s.:-»!^-«i-?.'5«« v. •
:3sd^lt&|feasi
•#::;'::|::iH
iuT«'tF<*,wgiiiiliui ti»^*7iyjff^'i^ju^i^"-M*«^T!aw»'i»ii«%C»TO
'
* '''
^^ifc^S^^lfei
.^raffJEcfet/'ffi*
:'f-^ SS?PfeS^«f-?'»l
:y^ipg|*il
.
^f :; ;:A/Yv\.
/' -T-^)
//
-------
THE' "ANACONDA" "COMFAM
WATER ANALYSIS '
Murray
12,10.34.224
DATE
Feb.
1960
ANALYST
Anaconda
CL
.PEL.
48
304
ppm
537
Np3
PP»
PH
8.6
Cond.
xanhos
1900
H003
Ppm
310
003
ppm
Na
ppm
391
,Mg '
ppm
Ca
Ma
ppm
'Fe
TDS
ppm
.1153
May
1960
50
516
:1640
300
-0.50
July i960
526
13-:
Sept
160
J>;ii 'X
NOT. '
- 1960
-------
Page 1 oft 4
From: "Wade Kress"
To: "Jonnie Head" ; "Nathan C Myers" ; "Sarah E
Falk" ; "Rodger F Ferreira" ; "Douglas P MeAda"
; ; "Jared Abraham"
; "Bruce D Smith" ; "James C Cannia"
Sent: Monday, May 04.2009 2:52 PM
Attach: Homestake_figures.docx
Subject: Figures used to determine APPROXIMATE location for flight lines.
Milton,
Several USGS personnel reviewed the area that was delineated last week during our conference call. To conduct
a hydrogeologic framework investigation in the delineated area the project would need to be funded at about 1.5
million dollars. Please keep in mind that this is an estimate and cost is largely driven by cost to fly the survey.
This cost can and does fluctuate depending on fuel costs. Please let me know if you have any questions. I have
attached a few figures showing regional topography and magnetic data and the approximate flight design.
Wade H. Kress
Supervisory Hydrologist
Texas Water Science Center
West Texas Program Office
U.S. Geological Survey, WRD
944 Arroyo Drive
San Angelo, Tx 76903-9345
325-944-4600 Office
325-280-1351 Cell
-/
5/5/2009
-------
o
o
£
-o
>
Si
I.
o
CL
O
to
o
I
5)
U.
-------
o
o
JO
•3
c
_o
"CD
o
u.
to
c
£3
s
-
-------
f'
Figure 3. Map showing conceptual flight path wjih tie lines for airborne EM and Magnetic surveys. Approximately 3,300 line kilometers {2050 miles).
.-. -— by TS*
-------
MINERALS
ANACONDA Copper7 Company
New Maxico Operations
P.O. Box 638
Grants, New Mexico 87020
505/876-2211
March 15, 1982
Milton Head
P.O. Box 2011
Milan, NM 87021
RE: Water Chemistry Analysis of Murray Irrigation Well
Dear Milton:
The Anaconda Minerals Company, Environmental Staff is enclosing, per
your request, the water chemistry analysis results for Murray Irrigation
Well. The information provided is all that could be found on the Well.
As far as'your request on the H.D. Chapman well; no information or results
could be found in our files" pertaining to that well or to a well listed
in your name. Someone else must have been conducting the samplings;it was
not Anaconda.
We hope this information fulfills your request of last week. If not,
don't hesitate to call us. •
Carl D. Wool folk//
Sr. Env. Eng.
cc: DLR
File
-------
THE ANACONDA COMPANY
WATER 'ANALYSIS
. 27.
.DATE
ANALYST
Cl
- pprrj
Z
ppm
NO-j
ppm
Na
Ppr
Cond'
unhos
pH
7-7
ppm
ppm
/U/i-
Ca
ppm
Mg
ppm
Fe
ppm
o.io
Mn
ppm
£0.1
TDS
-ppm
/Vov. /
-------
;
..
. ,..
jS " ,,
''" - "'T-'^'O
"
-------
TiiK ANACONDA COMPANY
/ Z-. /g. Z 7,
UATK
ANALYST
CL
ppm
pm
NO-)'
nnn
pH
ppm
HC03
nnm
CQi
ppm
Na
ppm
"MR
ppm
Ca
ppm
Mn
ppm
Fe
ppm
IDS
ppm',
433
7.5"
fog
MIL
<&.(€>
/ft
H^u^rfls-/,:
***&&&&
'"v?tx *- -
/»*<:.. !%
-------
WATER ANALYSIS
Murry 12.10,27,431
DATE ANALYST
July 1956 U.S.G.S.
Dec. 1958 Anaconda
Mar. 1959 Anaconda
June 1959 "
Sept. - 1959 "
Dec. 1959 "
May -I960 Anaconda
July I960 "
Sept. I960 »
Nov* I960 (DOWN FOR WINTER}
Jan. 1961 (DOWN FOR WINTER)
Mar. 1961 (DOWN FOR WINTER)
May 1961 Anaconda
J«/A/ /1 61
/
/
A / f / & / f f J\ _, yC-r/f \ f , .jL |
JJM wz (DO^^ for Wv/^;
faf A i / 4?y $ * t • T* ' *
/ $fir* f /Of ***"
AJ // i
i
1' /
AW W^ '
J^ /*63
Man I 1^43
M*y \ci^ "
Je//y /^43
rfJov/ I3i3
1 f tfft /" C/ / i
CL
ppm
72
76
77
78
81
81
82
78
81
, ISL-
77
/f
// ,„,
7?
79
53
fio
tfo
A)o
31
fj £s
/ /
/y j^
^
S04
ppm
392
380
337
380
401
387
403
399
390
%s£
391
4*1
3f?
w*-'
V/sr
V3&
*%ttrfp>i£m
JfM^iplc
S«Mfle
]l -y 1
If if $
3«m^};<^.
-^Cj m^iC
5— A
N03
ppra
6,9
10
15
10
13
6
4
8
6
2il7
8
/
r
?
• ft
i
Ph
7»3
7,6
7.2
7.4
7.3
7.3
7.8
7.2
7,0
-"--
7.8
?_2
7-3
7.2.
~7,4
7.2
1
B
7,-z.
7. ^
Cond.
umhos
— — • — —
1450
. 1410
1500
1500
/r*>
/£-f®
/6£0
/4dO
1 L£>Q
IfeOO
H003
ppra
392
402
410
409
^/m
405
y^f
Y/6
—
yt?
t/4
V/*?
efa^
003
NIL
NIL
NIL
NIL
AfM
Aftt
ritt-
/M>L
M/L
V/L
Mli-
Na
ppm
79
116
131
128
135
140
110
no
113-
120
/a
-------
San Andres
Ca Through Ion_Bal
Sample Point
Name Date
#1 Deepwell 5/22/1958
4/20/1979
5/8/1980
5/8/1980
7/2/1800
. 10/23/1980
5/11/1983
5/11/1983
12/20/1983
12/20/1983
3/21/1984
3/21/1984
3/21/1984
5/25/1984
5/25/1984
7/31/1984
7/31/1984
-> 7/31/1984
9/28/1984
12/29/1984
3/13/1985
6/27/1985
9/13/1985
12/20/1985
6/26/1986
9/17/1986
1/8/1987
3/30/1987,
Lab
UNK I
HMC
HMC
HMC,
HMC
IL
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
Ca Mg K Na
(mg/l) (mg/l) (mg/l)
-------
San Andres
Ca Through Ion_Ba!
Sample Point
Name Date Lab
#1 Deepweli 8/1/1994 ENER
11/16/1994 ENER
2/9/1995 ENER
5/10/1995 ENER
8/16/1995 ENER
11/15/1995 ENER
2/15/1996 ENER
5/15/1996 ENER
8/12/1996 ENER
10/30/1996 ENER
2/27/1997 ENER
4/29/1997 ENER
7/24/1997 HMC
7/24/1997 ENER
11/3/1997 ENER
2/4/1998 ENER
5/5/1998 ENER
8/3/1998 ENER
10/28/1998 ENER
2/3/1999 ENER
5/11/1999 ENER
8/17/1999 ENER
11/2/1999 ENER
2/1/2000 ENER
4/27/2000 ENER
8/2/2000 .ENER
11/21/2000 ENER
5/16/2001 ENER
Ca
(mg/l)
219
...
165
—
—
218
125
232
207
...
193
.
—
...
206
—
---
—
—
—
164
—
225
...
—
169
Mg
(mg/1)
72,0
...
74.0
—
—
73.2
38.6
73.1
65.3
—
61.7
—
—
66.7
...
...
...
—
...
65.9
...
74.2
—
...
65.6
K
(mg/l)
12.0
...
11.5
...
'
12.2
6.60
12,3
10.4
...
10.4
...
...
116
—
...
-.
. —
...
12.6
'
13.1
.„
...
11.8
Na
(mg/i)
317
...
307
...
—
310
393
322
309
...
303
—
...
310
...
...
—
—
...
267
...
302
...
...
232
HCO3
(mg/I)
—
—
459
...
...
645
464
627
582
...
608
—
...
605
...
.
...
—
...
46S
—
635
...
—
445
CO3
(mg/1)
...
—
< 0,100
—
—
< 0.100
< 0.1 00
< 0.100
< 0.1 00
—
0
...
...
—
—
< 1.000
—
—
—
—
—
< 1 .000
—
< 1.000
—
...
< 1.000
Cl
(mg/l)
...
215
—
—
222
148
235
210
—
183
""•-
"""
— ,.
..»
214
—
—
—
—
—
224
—
256
—
—
182
SO4
(mg/1)
723
696
689
580
742
390
727
751
733
701
440
630
...
641
748
647
681
641
755
811
752
722
763
744
716
736
718
523
TDS Cond(calc.)
(mg/I) (micromhos
1806
1948
1970
1716
999
1071
1999
1720
2030
1810
1140
1910
«„-
1650
2010 -
1860
1940
1730
1970
1820
2070
1980
2040
2000
2030
1780
1910
1660
* 2525
* 2631
* 2814
* 2623
* 1822
* 1711
* 3203
« 2497
...
* 2648
* 1822
...
2367
—
* 2802
* 2652
* 2443
* 2709
* 3081
* 31.0
* 2969 .
* 3160
* 2759
* 3013
* 2850
* 2846
—
lon_B
(ratio)
._
1.09
0.960
0.973
0.992
0.978
0.997
«,__
— ™
0.980
•
...
...
.~
.„
0,854
—
0.946
___
1.04
* Signifies Specific Conductivity from HMC
7/25/2005
-------
San Andres
Ca Through Ion_Bal
Sample Point
Name Date
#2Deepwell 3/3/1980
9/4/1 980
10/23/1980
11/6/1980
1/6/1981
3/16/1981
5/4/1981
7/1/1981
9/16/1981
12/23/1981
3/1/1982
7/29/1982
1/25/1983
4/7/1983
6/16/1983
12/21/1983
3/22/1984
5/25/1984
5/25/1984
5/25/1984
7/31/1984
7/31/1984
7/31/1984
9/24/1984
12/29/1984
3/13/1985
6/27/1985
9/12/1985
Lab
HMC
HMC
IL
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
Ca Mi K Na
(mg/l) (mg/l) (mg/l) (mg/l)
. _
207 62.0 13.0 259
265
' —
250
290
265
210
160
250
290
240 26.0 15.4 250
250
" 250
250
250 49.0 14.0 245
—
—
—
—
—
298 6.00 14.0 260
—
318 29.0 10.00 260
—
276 10.00 14.0 257
HCO3 C03
(mg/l) (mg/l)
549
558 0
523
—
—
602 —
561
563
374
553
558
• 549
531
573 0
481 0
549 • 0
—
...
,-
...
— .
—
437 < 0.0010
...
551 < 0.0010
—
548 < 0.0010
Cl
(mg/l)
160
135
139
156
-149
149
57.0
178
170
163
163
156
92.0
104
77.0
156
156
—
—
—
—
—
—
170
—
156
—
156
SO4
(mg/l)
668
669
650
659
653
646
656
638
662
713
713
650
664
666
670
669
—
—
...
—
—
629
702
779
762
702
682
TDS Cond(calc.)
(mg/l) (micromhos
1050
1927
1050
„»_
1640
1680
1600
1510
1620
1690
1620
1660
1670
1590
1540
1560
—
...
...
—
1620
1660
2430
1530
3310
1650
—
„„
' ___\
...
...
...
...
„__
— .
„«_
„__
....
mmm. '
2578
2125
2086
1930
1895
1998
2228
2193
2384
—
2346
—
lon_B
(ratio)
...
1.000
...
...
...
...
1.01
...
...
1.01
**.«,
...
™
...
1.02
1.02
—,
0.950
7/25/2005
-------
San Andres
Ca Through Ion_Bal
Sample Point
Name Date Lab
#2Deepwell 3/3/1993 HMC
5/14/1993 HMC
9/1/1993 ENER
11/8/1993 ENER
2/9/1994 ENER
5/5/1994 ENER
8/1/1994 ENER
11/16/1994 ENER
2/9/1995 ENER
5/10/1995 ENER
8/16/1995 ENER
11/15/1995 ENER
3/13/1996 ENER
5/14/1996 ENER
8/28/1996 ENER
10/24/1996 ENER
2/27/1997 ENER
4/29/1997 ENER
7/24/1997 ENER
11/3/1997 ENER
2/4/1 9i8 ENER
5/5/1998 ENER
8/3/1998 ENER
10/28/1998 ENER
2/3/1999 ENER
5/11/1999 ENER
8/17/1999 ENER
11/2/1999 ENER
Ca
(mg/l)
269
—
—
...
222
—
214
—
218
—
—
267
220
—
228
—
214
—
—
—
212
—
...
—
—
—
161
Mg K
(mg/f) (mg/l)
26.0 15.0
—
—
—
64.1 10.1
—
69.8 11.5
—
74.0 1 1 ,4
—
...
86.7 12.0
69.8 11,8
...
72.6 11.8
.
67.8 11.2
—
—
...
69.3 11.4
—
—
—
—
—
64.4 11.7
Na HCO3 CO3
(mg/l) (mgfl) (mg/l)
277 536 < 1.000
—
—
—
257 487 < 0.1 00
,_
256
—
250 549 < 0.100
—
—
253 560 < 0.1 00
263 565 < 0.100
—
264 555 < 0.1 00
—
246 539 0
—
—
—
257 558 < 1 .000
—
...
...
...
.
226 384 < 1.000
Cl SO4
(mg/I) (mgfl)
782
177 669
691
633
652
178 768
705
677
646
192 649
679
704
244 823
196 698
' 662
206 700
702
181 627
1031
730
642
195 661
697
716
732
693
704
197 684
IDS Cond(ca1c.)
(mg/l) (mieromhos
1870
1800
1761
1808
1777
1808
1714
1799
1790
1817
1813
1869
1854
1836
1860
1830
1800
1850
1850
1960
1850
1850
1860
1790
1780
1810
1790
1800
2349
2309
* 2370
* 2364
* 2185
* 2412
* 2357
* 2363
* 2497
...
* 2553
* 2526
...»
* 2739
___
* 2647
* 2350
* 2492
* 2699
* 2521
* 2597
* 2475
* 2453
* 2619
* 2806
„„„
* 3055
ion_B
(ratio)
1.01
...
...
0.958
— «
...
1.01
„„
...
0.957
0.971
.__
0.988
1.01
„„
...
...
0.976
__„
_.._
...
„__
_„
0.898
* Signifies Specific Conductivity from HMC
7/25/2005
-------
San Andres
Ca Through Ion_Bal
Sample Point
Name Date Lab
0943 8/21/1997 ENER
8/18/1998 ENER
9/2/1999 ENER
9/2/1999 ENER
B/23/2000 ENER
8/29/2001 ENER
8/29/2001 ENER
11/13/2002 ENER
10/27/2003 ENER
3/9/2004 ENER
12/8/2004 ENER
4/19/2005 ENER
0951 4/15/1993 UNK
10/5/1993 UNK
4/5/1994 UNK
8/31/1995 ENER
3/7/1996 ENER
10/22/1998 ENER
8/21/1997 ENER
12/17/1997 ENER
8/18/1998 ENER
8/19/1999 ENER
9/17/1999 ENER
10/19/1999 ENER
11/2/1999 ENER
12/10/1999 ENER
1/20/2000 ENER
8/9/2000 ENER
Ca
(mg/l)
9.20
8.40
—
—
—
—
—
...
166
—
165
140
...
160
138
87.2
27.6
153
148
148
...
...
...
—
...
...
...
Mg
(mg/l)
5.60
6.50
...
—
...
—
...
—
.„
52.9
—
54.3
42.0
...
46.0
44.0
69.0
3.70
43.0
42.3
43.2
...
...
—
...
—
—
...
K
(mg/l)
2.90
4.30
—
...
...
...
...
—
—
8.80
...
8.80
4.70
._
5.20
5.10
9.80
11.7 '
5.20
5.20
5.60
...
—
.
...
...
...
...
Na
(mg/l)
654
623
...
—
...
...
...
...
...
314
...
282
74.0
...
75.0
77.0
117
2.30
75.6
73.0
76.5
...
...
...
—
—
—
...
HCO3
(mg/l)
215
222
...
...
...
...
...
...
...
391
...
399
260
—
340
325
113
94.5
346
340
342
...
...
...
...
...
...
...
C03
(ma/i)
5.80
< 1.000
—
...
...
—
—
—
< 1.000
—
< 1.000
< 0.100
...
< 0.1 00
< 0.100
< 0.1 00
< 0.100
< 0.100
< 0.100
< 1.000
—
...
...
...
—
—
...
CI
(mgfl)
91.0
83.9
—
...
—
—
—
—
188
—
181
60.0
55.0
57.0
54.0
88.9
3.10
50.0
51.0
50,3
—
—
—
—
...
_.
...
SO4
(mg/l)
1180
1100
1170
# 1100
1070
1000
# 1000
1080
1090
793
690
712
350
340
350
327
567
7.40
330
314
323
333
313
335
335
350
333
270
# Signifies
* Signifies
TDS Cond(calc.) lon_B
(mg/l) (micramhos (ratio)
2040
1980
2070
* 2020
2010
2040
# 2030
2010
2030
1830
1720
1680
890
830
890
841
993
104
872
867
872
842
855
838
857
861
824
623
* 3178
* 3046
* 3919
«...
* 3832
* 3822
...
* 3840
* 2899
* 2505
* 2315
* 2365
1422
„„„
1514
* 1262
* 1530
* 213
* 1388
* 1243
* 1478
...
* 1185
* 1221
* 1222
* 1200
* 1240
• 1226
0.954
0.973
...
...
...
...
...
0.939
0,951
1.04
...
1.05
1.02
0.950
1.16
1.05
1.05
1.05
...
—
Quality Control Sample
Specific Conductivity from HMC
7/25/2005
-------
San Andres
pH Through Th-230
Sample Point
Name Date Lab
#1 Deepwell 5/22/1958 UNK
4/20/1979 HMC
5/8/1980 HMC
5/8/1980 HMC
7/2/1980 HMC
10/23/1980 1L
5/11/1983 HMC
12/20/1983 HMC
3/21/1984 HMC
9/28/1984 HMC
3/13/1985 HMC
9/13/1985 HMC
9/17/1986 HMC
3/30/1987 HMC
9/30/1987 HMC
3/29/1988 HMC
9/27/1988 HMC
12/19/1989 HMC
5/9/1990 HMC
5/22/1991 HMC
8/22/1991 BARR
5/4/1992 HMC
8/12/1992 ENER
5/14/1993 HMC
9/1/1993 ENER
5/5/1994 ENER
8/1/1994 ENER
11/16/1994 ENER
pH
(std. units)
—
7.10
7.00
7.40
7.00
7.00
7.50
7.20
7.10
7.10
7.00
7.60
7.70
7.00
7.60
7.50
7.00
7.30
7.10
—
7.20
—
7.40
...
7.17
...
—
Unat
(mg/l)
0.212
< 0.0085
< 0.0085
< 0.0085
0.0200
< 0.0085
0.0068
0-0102
0.0136
...
< 0.01 00
<: 0.01 00
< 0.01 00
< 0.01 00
0.0254
0.0424
0.0170
< 0.0085
0.0763
0.0254
—
0.0170
0.0120
0.0170
0.0160
0.0130
Mo
(mgfl)
0.220
0.0200
0.0200
0.0200
< 0.0500
0.0100
0.0200
0.0100
0.0700
<: 0.01 00
< 0.01 00
0.0100
0.0100
0.0100
0.0100
0.0100
< 0.0 100
< 0.01 00
<. 0.0100
...
0.0100
...
< 0.01 00
„.
< 0.0300
...
—
Se
(mg/i)
0.0300
0.0200
0.0200
< 0.0100
< 0.0020
•sO.0100
0.0100
0.0100
0.0100
0.0100
< 0.01 00
0.0100
0.0100
< 0.01 00
0.0100
< 0.01 00
< 0.0100
0.0100
< 0.0100
—
0.0080
...
< 0.0100
< 0.0010
< 0.0050
< 0.0100
< 0.01 00
NO3
(mg/i)
1.20
0.860
1.30
1.10
< 0.100
2.20
0.700
2.50
12.0
8.40
4.60
6.00
2.90
0.900
1.40
1.000
2.00
0.200
1.80
2.00
—
1.70
—
1.70
—
<0.100
—
—
Ra226 Ra228
(pGi/l) (pCI/l)
0
1.50
0.900
1.90
0.310
0.500
2.30
2.40
0.200
0.200
1.50
0.800
1.000
2.30
0.200
0.200
< 0.100
* 0.400
—
3.10
— ...
2.70
* 0.800
—
1.30 < 1.000
—
_._
Cr V
(mg/l) (mg/l)
< 0.01 00
< 0.01 00
< 0.0100
—
< 0.01 00 < 0.0500
< 0.0100
< 0.01 00
< 0.0100
< 0.0100
< 0,01 00
< 0.01 00
< 0.01 00
< 0.01 00
< 0.0100
< 0.01 00
<: 0.0100
< 0.01 00
< 0.01 00
< 0.01 00
_-
< 0.0100
...
< 0.0100
... ._«
< 0.0500 < 0.01 00
:
...
Th23Q
(pCl/l)
._
—
...
._
...
...
...
—
-..
...
< 0.200
...
11
* Signifies Specific Conductivity from HMC
7/25/2005
-------
San Andres
pH Through Th-230
Sample Point
Name Date
#2Deepweli 1/11/1978
3/20/1978
5/22/1978
7/24/1978
9/15/1978
11/10/1978
1/12/1979
3/5/1979
5/4/1 979
7/371 979
9/4/1979
11/2/1979
1/3/1980
3/3/1980
9/4/1980
10/23/1980
11/6/1980
1/6/1981
3/16/1981
5/4/1981
7/1/1981
9/16/1981
12/23/1981
3/1/1982
7/29/1982
1/25/1983
4/7/1983
6/16/1983
Lab
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
IL
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
HMC
pH
(std. units)
7.60
7.50
7.20
7.35
7.80
7.40
7.70
8.20
8.10
8.00
7,70 •
7.10
7.50
7.75
7.90
7.40
7.80
7.25
7.70
7.60
7.40
8.00
8.00
7.80
8.50
7.90
7.80
7.00
Unat
(mg/l)
0.0678
0.0254
0.187
0.0424
0.0170
0,0509
< 0.008S
0.0594
0,0933
0.102
0.0848
< 0.0085
< 0.0085
< 0.0085
< 0.0085
< 0.01 00
< 0.0085
< 0.0085
< 0.0085
< 0.0085
< 0.0085
< 0.0085
< 0.0085
< 0.0085
< 0.0085
< 0.0085
< 0.0085
< 0.0085
Mo
(mg/I)
0.0300
0.0100
< 0.01 00
0.0300
0.0300
0.0300
0.0900
0.110
0.0800
0.100
0.130
0.0600
0.0900
0.0500
0.0200
< 0.0500
0.0300
0.0200
< 0.01 00
0.0200
0.0200
0,0300
0.0200
0.0300
0.0400
< 0.0100
0.0200
< 0.01 00
Se
(mg/l)
0.0100
< 0.01 00
< 0.0100
0.0400
0.0200
0.0100
0.0100
0.0300
0.0300
0.0800 "
0.0100
0.0100
< 0.0100
< 0.0100
0.0200
< 0.0020
0.0200
< 0.01 00
0.0200
< 0.01 00
< 0.01 00
< 0.01 00
< 0.0100
< 0.01 00
< 0.0100
0.0300
0.0300
0.0100
NO3
(mgfl)
1.20
1.50
2.10
1.20
1.20
1.80
2.10
1.80
1.40
1.35
1.35
1,20
1.20
1.10
1.20
3.50
1.10
5.60
1.000
1.05
1.10
5.40
1.20
1,10
1.000
1.30
0.700
1.30
Ra226
(pCi/l)
2.00
1.60
2.90
1.60
1.60
2.90
1.50
2.20
1.60
1.30
1.80
0.200
0.700
1.10
0.600
0.360
1.10
1.000
1.70
1.40
0.500
3.80
120
1,30
4.60
1.000
2.40
0.900
Ra228 Cr V Th230
(pCi/l) (mg/l) (mg/l) (pCI/i)
< 0.01 00
< 0.01 00
< 0.01 00
< 0.01 00
< 0.01 00
< 0.01 00
< 0.01 00
< 0.01 00
< 0.01 00
< 0.01 00
< 0.01 00
< 0.01 00
< 0.01 00
< 0.01 00
< 0.0100
< 0.0100 < 0.0500
< 0.01 00
< 0.0100
< 0.01 00
< 0.01 00
< 0.0100
< 0.0100
< 0.01 00 . —
< 0.01 00
< 0.01 00
< 0.0100
< 0.01 00
< 0.01 00
13
7/25/2005
-------
San Andres
pH Through Th-230
Sample Point pH
Name Date Lab (std. units)
f2DeepwelI 8/28/1996 ENER
10/24/1996 ENER
4/29/1997 ENER
11/3/1997 ENER
2/4/1998 ENER .
5/5/1998 ENER
11/2/1999 ENER
4/27/2000 ENER
5/2/2001 ENER
5/7/2002 ENER
5/13/2003 ENER
5/13/2003 ENER
5/10/2004 ENER
5/4/2005 ENER
0806 7/25/1956 UNK
9/18/1981 HMC
11/9/1994 ENER
7/24/1996 ENER
11/12/1996 ENER
9/2/1997 ENER
8/10/1998 ENER
8/22/2000 ENER
8/24/2001 ENER
10/17/2002 ENER
10/27/2003 ENER
4/21/2005 ENER
0943 8/28/1956 UNK
8.01
7.83
...
...
7.80
8.16
7.79
7.79
8.10
7.86
# 4.89
7.53
7.71
7,30
_.
7.58
8.08
7.79
7.95
7.93
...
...
...
...
7.62
7.80
Unat
(mgfl)
0.0193
0.0083
0.0110
0.0250
0.0109
0.0117
0.0106
0.0119
0,0100
0.0090
0.0113
# 0.0120
0.0109
0.0091
...
< 0.0085
0,0120
0.0130
0.0139
0,0100
0,0175
0.0180
0.0180
0.0150
0.0152
0.0152
—
Mo
(mg/l)
< 0.0300
< 0.0300
< 0.1 00
0.0073
...
< 0.0300
< 0.0300
< 0.0300
< 0.0300 ,
< 0.0300
< 0.0300
# < 0.0300
< 0.0300
< 0.0300
...
0.0200
< 0.0300
< 0.0300
< 0.0300
< 0.0300
0.100
...
...
...
...
< 0.0300
—
Se
(mg/l)
0.0090
0.0090
0.0040
0.0060
0.0080
0.0080
< 0.01 00
< 0.0050
0.0090
0.0100
0.0130
# 0.0090
0.0070
0.0120
...
< 0.01 00
0.0080
0,0080
0.0080
0.0070
0.0090
0.0080
0.0110
0.0100
< 0.0050
< 0.0500
—
NO3
(mg/l)
1.96
2.25
...
—
1.71
2.05
2.39
3.17
2.58
2.30
# 2.50
2.61
2.40
6.90
3.60
5.16
4.06
4.50
4.42
4.30
...
—
...
...
3.90
0.600
Ra226
{pCM)
0.400
0.800
...
—
0.300
< 0.200
0.400
< 0.200
< 0.200
0.200
# < 0.200
< 0.200
0.500
—
0.500
0.300
< 0.200
< 0.200
< 0.200
0.500
...
—
...
—
0.300
—
Ra228 Cr V
(pCi/l) (mgil) (mg/l)
< 1.000 < 0.0500 < 0.01 00
— < 0.0500
< 1.000 — < o!oi oo
—
< o.osoo
< 0.0500
< 0.0500
< 1.000 < 0.0500 < 0.01 00
< 0.0500
< 0.0500
# < 0.0500
< 0.0500
< 0.0500
—
...
2.10 < 0,0500 < 0.01 00
—
< 1.000 < 0.0500 < 0.0100
... -
—
...
...
...
—
—
...
Th230
(pCI/l)
< 0.200
—
< 0.200
—
—
...
...
0.400
—
...
—
—
...
•
—
< 0.200
—
< 0.200
_.
...
...
...
...
_.
—
—
it Signifies Quality Control Sample
15
7/25/2005
-------
Sample Point
Name
Date Lab
pH
(std. units)
Unat
(mg/1)
Mo
(mg/l)
San Andres
pH Through Tti-230
Se
(mg/l)
NO3
Ra226
(pCM)
Ra228
(pCi/l)
Cr
V
(mg/l)
Th230
(pCf/l)
0951
11/2/1999
12/10/1999
1/20/2000
8/9/2000
10/17/2002
10/27/2003
12/8/2004
4/25/2005
ENER
ENER
ENER
ENER
ENER
ENER
ENER
ENER
7.78
0.0230
0.0204
0.0316
0.0030
0.0280
0.0314
0.0272
0.0281
< 0.0300
< 0.0300
0.0030
0.0060
< 0.0050
< 0.0050
< O.OOSO
< 0.0050
0.0080
< 0.0500
4.40
0.200
17
7/25/2005
-------
Giauts Project
Homestake Mioing Company of California
x Alan D. Cox
Project Manager - Grants
Larry Carver
r ; P.O. Box 2970
-:• Milan, NM 87021
6 November 2008
j^ J,
- Re: Analytical Data for Well 0806-R
Dear Mr. Carver:
Enclosed are copies of the laboratory Analytical Report for the sample collected from your well
0806-R on September 24,2008. Thank you for allowing us access to take water samples, and
request your permission for continued access to take future samples.
1 Should you Have any questions concerning this information, I can be reached at 287-4456 ext,
25.
Sincerely yours.
* HOMESTAKE MINING COMPANY OF CALIFORNIA:.
' '
.'!«' J?>,AlanD. Cox,
" ''^Enclosure :.
Vt- - "|.O.Box98/Hwv.605
I; %\,<4>*«K'
Grants, NM 87020
Tele; (5051287-4456
Fax:(505)287-9289
-------
•M'fg^KSyi^^'---''- ENERGY LABORATORIES, INC. < 2393 SaltCreek Highway (82601)- P.O. Box 3258 • Casper, WY 82602
'yi^MSM^M^Totl Free 88&235.0515 "7.235.0515 > Fax '307,234,1639 ' casper@enerc com- www.energyiab.com
•' '.-'.JffiPP^S^?g|B^- • .
i ' ;vil|S|iisSl^v''St\ ;i; ''"':
: .^'IS^ftWJS-*'"'- ' " -' ' -
I ••-'' "1Ueiitr.;:;f:Homestake Mining Company
: iToject: : Giants
"• 3- a'.V'i. '.,;'.•, -. ,
^Lai>:iD: •'" C08091 1 50-00 1
aClieni Sample ID: OS06-R
•^'vW.'Vv' '
:'••;• :SH% ::/;:•?'•"• "' •• ,1"* **
^MAJORJONS
K.?;;05r5-|;A[ka!inJty> Total as CaC03
•:?||3fJQ6.J?£arbo'riale as CO3
•- VivbpSrtBicarbonate as HC03
i^lorjtKiCajcaurn-' ..•'•'
• x/'OO^&Chloride^'i. ,;^" ;
;i;i; WSjIjMagnesiiirn,, •'. . '; •
;^39|lMltreig^n^:Nitrafei-Nitrite as N
'':•'• 003 '•'' Potassium .
..-•;<• ,,••?•'•••"•.,• ...- •-- "
~:~ 004 A ,' Sodium :
•- '->'.r: --" ; ' ;' ''-''I.;.
.:- -" "•'<•"' ' - '
: .PHYSICAL PROPERTIES
'. ' '009.;/pH: .
i . 010j';Solids; Total Dissolved TDS @ 1 80 C
....cTALS- DISSOLVED
\'p-,036.j Molybdenum
,- -^p40,.;i;;Selen|um. ' " . '
,.;;;:.^01^ML|raniurn;..- ; ":• .
• ••"4--.244KOrarilum Precision (±)
-• '-.-.•'-,•--•.'}!-- :-.;-i ;.•.;.... />-.. -,-' •..-.•'
-• :i 114|:"JJraniyrn,'Actiyity-
. vi.13:^:yigniumt Activity precision (±)
j^^ipiybQDES-- DISSOLVED
•:::fJ45i;|i,acfym;226
'-5;v245*|laciiUrn 226 precision (±)
PiSSillPlI^1}}:?26 WDCJ
^2|6.||jpadiipriV226altu v\i -
-:-:^;25§|g|dfumJ226.altu precision (±)
•i7.||^ifS^wirj"226 aitu MDC
.::,;-li2^A?53aiance(± 5) .
/ '!/; .^-.vf;;.''.- •-' y. -.''.'. ' '
-•: 19S'J ''Qstlons -•'
;ri"079.'ASftl'(cls, Total Dissolved Calculated
W.2pOy&pS Balance (0,80 - 1.20}
.t&Sijte'" ' :• '• '
-•-.' .••=%^4'>>.-. •>•.-.<..••• - - '
LABORATORY ANALYTICAL REPORT
MCL/
Result Units Qual RL QCL
346 mg/L ' 1
<1 mg/L 1
423 mg/L 1
234 mg/L 0.5
189 mg/L 1
76.8 mg/L 0.5
4.1 mg/L 0.1
9.9 mg/L 0.5
211 mg/L D 4
634 mg/L • 1
7.13 s.y. 0.01 -
1630 mg/L 10
<0.03 mg/L 0.03
0.008 rng/L 0.005
0.0178 mg/L , 0.0003
0.00205 mg/L 0.00003
1.2E-08 UCi/mL 2.0E-10
1.4E-09 uCi/mL 2.0E-11
0.41 pCi/L
0.15 pCt/L
0.17 pCf/L
4.05-10 uCi/rnL
2.0E-10 uCi/mL :
2.0E-10 uCi/mL
3.13. %
25.8 meq/L
27.4 meq/L
1730 mg/L
0.940 unitless
ER
x_
Report Date
Collection Date
Date Received
Matrix
Method
A2320 B
A2320 B
A2320 B
E200.7
E300.0
E200.7
E353.2
E200.7
E200.7
E300.0
A4500-H B
A2540C
E200.8
E200.8
E200.8
E200.8
E200.8
E200.8
E903.0
E903.0
E903.0
E903.0
E903.0
E903.0
Calculation
Calculation
Calculation
Calculation
Calculation
NOV 0
: 10/27/08
: 09/24/08 12:37
: 09/29/08
: Aqueous
Analysis Date / By
09/30/08 20:56 / IJf
09/30/08 20:56 / ijl
09/30/08 20:56 / Ijl
10/1 5/081 4:08 /cp
10/02/08 17:25 /dnp
10/1 5/08 14:08 /cp
10/02/081 5:35 /eli-b
10/15/08 14:08 /cp
10/1 5/081 4:08 /cp
10/02/08 17:25 /dnp
09/30/08 09;35 / dd
10/01/08 09:13 /jah
10/04/08 02:00 /ts
10/21/08 18:06 /sml
10/04/08 02:00 /ts
10/04/08 02:00 /ts
10/04/08 02:00 /ts
10/04/08 02:00 /ts
10/14/081 5:07 Mrs
10/14/081 5:07 Mrs
10/1 4/08 15:07 Mrs
10/14/08 15:07 Mrs
10/1 4/081 5:07 Mrs
10/1 4/081 5:07 Mrs
10/22/08 10:21 /sdw
10/22/08 10:21 /sdw
10/22/08 10:21 /sdw
10/22/08 10 '21 / d
10/22/08 10:21 /sdw
Report;";:
RL - Analyte reporting limit.
.• QCLr.Quality control limit.
MDC - Minimum detectable concentration
MCL - Maximum contaminant level.
NO - Not detected at the reporting limit.
D - RL increased due to sample matrix interference.
-------
Grants Project
Homestake Mining Company of California
Alan D. Co*
Project Manager - Grants
16 January 2008
Larry Carver
P.O. Box 2970
Milan, NM 87021
Re: Analytical Data for Well 0806
Dear Mr. Carver;
Enclosed are copies of the Laboratory Analytical Report for the sample collected from your well
0806 on October 2, 2007. Thank you for allowing us access to take water samples, and request
your permission for continued access to take future samples.
Should you have any questions concerning this information, I can be reached at 287-4456 ext.
25.
Sincerely yours,
HOMESTAKE MINING COMPANY OF CALIFORNIA
AlanD. Cox
Enclosure
$
o
u ®
u d
>"*
P.O. Box 98/Hwv. 605
Grants. NM 87020
Tele: (505) 287-4456
Fax: (505) 287-9289
-------
GRANTS PROJECT Alan Z>. Cox
Project Manager - Grants
11 June 2005
Larry Carver
P.O. Box 2970
Milan, NM 87021
Re; Analytical Data for Well 0806
Dear Mr. Carver,
Per your request enclosed is a copy of analytical data for a sample date of April 21, 2005 on your
well as referenced. Thank you for allowing us access to take water samples, and request your
permission for continued access to take future samples.
Should you have any questions concerning this information, I can be reached at 287-4456 ext. 17.
Sincerely yours,
HOMESTAKE MINING COMPANY OF CALIFORNIA
AlanD. Cox
Enclosure
Hwv. 605/P.O. Box98 Grants,NM87020 Tele: (505)287-4456 Fax: (505) 287-9289
-------
ENERGYLABORATQP'*S, INC. • 2393 Sail Creek Highway (82801)'P.O. 8^3258 ' Casper, WY 82602
Toll Free 888,235,0515 • i 235,0515 • Fax 307.234.1639 > casper@emrgyl m ' www.energytab.com
LABORATORY ANALYTICAL REPORT
Client: Homestake Mining Company
Project: Not Indicated
Lab ID: CG5Q41023-002
Client Sample ID: 0806
Report Date: 05/18/05
Collection Date: 04/21/05 14:00
Date Received: 04/26/05
Matrix: Aqueous
Analyses
MAJOR IONS
075 Alkalinity, Total as CaCO3
006 Carbonate as COS
005 Bicarbonate as HCO3
001 Calcium
007 Chloride
002 Magnesium
039 Nitrogen, Nitrate+Nttrfte as N
003 Potassium
004 Sodium
OOB Sulfate
PHYSICAL PROPERTIES
009 pH
" 010 Solids, Total Dissolved TDS @ 180 C
METALS - DISSOLVED
036 Molybdenum
040 Selenium
015 Uranium
244 Uranium Precision (±)
114 Uranium , Activity
113 Uranium, Activity precision (±)
RADIQNUCUDES - DISSOLVED
045 Radium 226
245 Radium 226 precision (±)
256 Radium 226 aitu
258 Radium 226 aitu precision (±)
DATA QUALITY
192 A/C Balance (± 5)
194 Anions
195 Cations
079 Solids, Total Dissolved Calculated
200 TDS Balance {0.80 -1,20)
.teport RL - Analyte reporting limit
Definitions: QQI . Qua|itv control limit.
Result
331
<1
404
188
193
63.8
3.9
9.3
193
607
7.62
1510
<0.03
O.05
0.0152
0.00005
1.0E-08
3.1E-11
0.3
0.3
3.0E-10
3.0E-10
-3.52
25.0
23.3
1470
1,03
Units
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
.mg/L
mg/L
mg/L
mg/L
s.u.
mg/L
mg/L
mg/L
mg/L
mg/L
uCi/mL
uCi/mL
pCi/L
pCi/L
uCi/mL
uCi/mL
%
meq/L
meq/L
mg/L
dec. %
MCL/
Qual RL QCL
1
1
1
0.5
1
0.5
D 0,2
0.5
D 0.5
1
0.01
10
0.03
0.05
0,0003
2.0E-10
0.2
2.0E-10
Method
A2320B
A2320B
A2320 B
E200.7
E200.7
E200.7
E353.2
E200.7
E200.7
E200.7
A4500-H B
A2540 C
E200.8
E200.8
E200.8
E200.8
E200.8
E200.8
E903.0
E903.0
E903.0
E903.0
Calculation
Calculation
Calculation
Calculation
Calculation
Analysis Date / By
05/02/05 13:43 /sib
05/02/05 13: 43 /sib
05/02/05 13:43 /sib
05/1 1/051 9:46 /cp
05/11/05 19:46/cp
05/1 1/051 9:46 /cp
04/27/051 2:52 /jal
05/1 1/051 9:46 /cp
05/1 2/051 6:40 /cp
05/1 1/051 9:46 / cp
04/27/0515:07/sl
04/27/0516:09/sl
05/05/05 09:47 / bws
05/05/05 09:47 / bws
05/05/05 09:47 / bws
05/05/05 09:47 /bws
05/05/05 09:47 / bws
05/05/05 09:47 / bws
04/28/05 15: 45 /trs
04/28/05 15:45 /trs
04/28/05 15:45 /trs
04/28/05 15:45 /trs
05/1 7/05 11:24/smd
05/17/05 11:24/smd
05/17/05 11:24/smd
05/1 7/05 11 :24/smd
05/17/05 11:24/smd
MCL - Maximum contaminant level.
ND - Not detected at the reoortina limit.
D - RL increased due to sample matrix interference.
JUN 0 3 2005
n n B n 4. 1 n ? 3 Paae
-------
Supplement to New Mexico Environment Department Superfund Oversight
Section Residential Well Sampling and Analysis Plan
May 2007
CERCLIS # NMD007860935
Milan, New Mexico
Prepared by David U Mayerson
-------
New Mexico Environment Department Superfund Oversight Section
Supplement to Homestake Uranium Mill site residential sampling and analysis plan
Table 3: Wells proposed for ground water sampling for investigation of uranium
contamination in Well RW-46 (HMC #986}
HMC (NMED)
well number
986 (RW-46)
955 (RW-43)
822
949
943
987
991
CW-43
CW-39
942
993
Completion
formation
San Andres
%
San Andres
San Andres
San Andres
San Andres
San Andres
San Andres
Lower Chinie
Lower Chinie
Alluvium
Alluvium
Last ground water
sample dissolved
uranium
concentration [mg/L]
(Date sampled)
0.0458(5/2/06) .,
0.0054 (5/1/06)
0.096(11/20/96)
0.0078(11/20/96)
0:0149 (12/1 9/06)
0.011 (11/3/95)
<0,01 (11/8/95)
0.0386(11/14/06)
0.0332(11/28/06)
0.0584 (8/9/05)
no data
Rationale for sampling
(gradient noted is relative to
the SUBJECT WELL)
SUBJECT WELL: Uranium
concentrations exceeded
standards in 2006, and
represent an increase from only
previous sampling in 1995
Cross-gradient," located next to
subject well
Downgradient; sampling in 1 995
and 1996 show increasing
uranium concentration trend
Cross-gradient
Downgradient
Cross-gradient
Cross-gradient
Cross-gradient in overlying
formation
Upgradient in overlying
formation.
Cross-gradient In overlying
formation
Cross-gradient in overlying
formation; closest well to subject
well.
Page 7 of 16
-------
'' • '''
\ * I ' > ' I
* « ttA l i f
-------
HOMESTAKE-SAP1N
TAILINGS POND
OVERHEAD
TRESTLE^]
^ / -30
GATE
TO
BALL PARK
G>—UNCASED WELL
HOMESTAKE-PARTNERS
MILL-SITE '
JU-NE -s^=ss- I960
Sec,26 635
T.I2N.,R.IOW.
300
-------
HGMESTAKE-
ANALYTICAL tAfiO,, .
REPORT*
ff1!
.
\-:
\
V
'
•- ffjr*. szzfSL.1""' * ***""-"*.*"*.- '-^,* ' .T*' ' " ,**: , , jr .".rrj:
jij_ t ;
Cased Hole HE Corner of See. 51
" # 1
> i
( A
"13 " \- 1
* # 8
.,""'• ' i ' i
tola ncsar ofi'lce - Ooisp 11 j
Observation hole ff 5
. « B _$ 6 'I
. .
. « « # g . !
. , . — , _ .. ,. —,.. - ., — _.._ ™™ - , .,,-._- ..-.._,.,
i* rj*
H 3 — M T * r 'i
DAtE %
-.'• ^-iii","~ -"'
\ ,
j
J
t * '
^ ^TJ',1
^•^
;
^ J> JLQ *
• " • I
i ,
.00035 »• 10,25
.0222 1.71
;
.,0003? j.., ktlQ s
.00057
.00021
i .
'
.
*- * .--.— •-.—
/ & • i
• .-.~, . . . .,_.!--.
,
f
V
,«-_»_^^rf._.^.-. . . „, ... . -™~—., ,^B,,,^ . ._
,"
**/^ L^. -3
//51 r^ f //) ,JA, / ' f //i yii^
fX L ^ -jo t-^ X r ^ *^^
^ **"**
* ',, - .. -— „. — . .. , . — . . -,._.
\,
•^ ., « •*. •
,-
-^. , , ..«__-,
*
^ *
5-.. -<> /o
^
;— ' - •
i
i
i
12.81 S
,. i]
1
Z/1 ' pya • ppa
•••}•• ';vr.s.s • i-rr* 1 r "• i.,— * '*
4000035 .
»o»aiP
-.,.» | ,
,000013.
.000020
.....
i
t
4, 70 i .000017
, ..' f^ -i-
i
j..
! ' 'i
j
1 •><».•. »*-.. .^n. «•-» V,
L
r"""~ ' "
1
1
'-
..... ., „. _
1
i
j
...
j
,.
'
•y i
.000083
... 9A ..
2io
1915
_»OOQC-6$ J
-wta- ^ffotal Dia X iirf
.i.,--5. %»rs,r< JTT '--rr.- is— .'«r • *. as. -..•
i
; _ ,, l" .
45Q ! .0427
.. : ' '
j
i
j ' " • "
..235. ; .
*3 , •
i
„..:...
i s*i/f~7\ 2250 • j 4055& ' '
\ f ',
58S .- ! ^7 ^ , 15OD t>0673
_.
.OCX310 - ! 563
•>•-•}*
1 ,
.00014 j
T"
;
• —»«•
445
r • •—
)
1 . . l • .... . .
j
'
i
1 , j
-./v.^' •' j . - ._ . 4» . .
i 1
-', •*jr'"^ (
!
„... .
'.
*
«!
< '
i;
!i
i
i!
., m. ,
i
i)
« i ,. .
... |
i
\
i
-
i *
t ..... .. -•• * «
i
i
! • 1
'tSf>'f''&t\ ^*^0 ' *-H'-
-• „„„* .. ^.1 .
,
i ' 4/7 f . 900 . i0673
1 *
/ • .
;. i^.l.... . .,, .. ,
1 "'
...
i
t
i
j
i
t
i
1
_ ^ _.
1
i
•
i
1
. • 1
I
i j
' i t
i
!
jf **'•*•'
SIGNED
OATI
. ..
-------
• HOMBSTAKE - NEW MEXICO PARTNERS,
. ~ DRILL HOLE -SAMPLES -,
APRIL/ I960
SUSPENDED SOLIDS
mg/1
Not measured
72,400
6/730
•843
900
SAMPLE
NUMBER
# 5
# 6
# 8
# 9
#13
#14 ,
#15
#20 MS NP
North ES NP
East N Iff
DISSOLVED RADIUM
0.18 uug/L
0.24 uug/L
1.79 uug/L
0.22 uug/L
1.88 uug/L
2.23 uug/L
1.19 uug/t
24.3 uug//-
0.79 +'
1.26 ^L
SUSPENDED RADIUM
3.89 uug/g
2.56 uug/g
8.25 uug/g
6.91 uug/g
22.3 uug/g
21.6 ugg/g
9.9 uug/g
161 uug/g
5.66 /••
8.40
-------
G
Ch*rl** C.
Environmental S.nll.Uon S*r*lc»»
$F1t ~ •
40t
NEW MEXICO
DEPARTMENT OF PUBLIC HEALTH
February 7, 1961
it, Don Akin "-• "^
State Engineer Office
. Capitol Building
Santa Fe, New J/jexico •
Dear Kr, Akin:
• ,'..." "
" IB August of 1960^ Mr. Gene Chavez of your office collected a number of water sanpO.es
• ' -from newly drilled testholes in the area of the Hose stales -Sapin and Home stake -Partners
/-uranium mills. These water samples were analysed for Radiuia 226 by the Robert A.
Taft Sanitary Engineering Center in Cincinnati, .Ohio. Results of these analyses are
as follows;
" Sample Ho.
. ' 5 ' .1.8 •
9 ' .0.3 '
18 ,3.1-
6 , .-,0.7,
Korwal baaigroucd radiation for ground water in Hew l.'exieo should be 0.1 uug RaAiter.
It is felt that these analyses indicate a definite pollution of the shallow grourd
'water table' by the uraniujn mill tailings ' ponds. As this constitutes a fairly serious
situation, our office intends to collect additional sanples from these and other
'drill holes in the near future. V/e have requested that the- Public Be'alth Service •
perfors analyses for Radium 226 for us on these additional samples. As soon as'u's
are notified to the affirmative, Yfe v/ill proceed vrilth our sampling prograu.
In vie*.? of our joint responsibility and interest in protection of the water quality,
your continued interest is' appreciated. Should you have any consents or suggestions
for further surveillance of ground v,rater- in this area, plsase contact our office. •
John W. Kernnndes •
/ Associate Engineer
•Environinsntal Sanitation Services
-------
Cettf'i;
(S
* - e
° - (7/1
S3 ~ £
-------
''Of
-------
-------
-------
NEW
^ DEPARTMENT OF PUBLIC €f ~'N"t"''"" '" : ^
fc'iivlronMntal sanitation services
403 Galisteo Street
Santa Fe, New Mexico
Dated J.larch 29. 19ol
The following chenical analysis based upon a sample of water recently submitted from your supply has
been reported to us by the chemistry department of the State public Health Laboratory. It is here-
with forwarded for your information.
Tfwv Grants . COUHTY Valencia
nevrn np SUPPLY Hbmestaie-Saain'
POINT OF COLLECTION Drill Hole #15
DATE COt.LECTEn jr»lTl6l,.a ,,
LAB »n, #T3
RESULTS OF ANALYSIS -.__"''
"rMtfr Hni»«
OJrOr N»'"«? TH O
TtsmpetfaiuciSs «r-^».*.^— »»—» BC pH «•«£?. t-JS**-*
-. f^j'\ s
Totfll Swidiip. 3263 mg/t
Noa-filf arable Residue 2Q4Q mg /'
^ Fjlrerable Rasidue.. . 122J!., mg/T
Nitrates (as NOa) „ _'i
Total Alkalinity (as CaCOi)
Rtrsirbonaf
Chlorfdas (as Ci)
Sa^ium {fl^ N*?)
Calcium (as G»)
Rcosrk^ r ..«««. - - -^ • - -
—,mg/1 Sulphates (as SO4 )..._.. 4^»^— :-«rti_mg/l
_208 mg/i phosphates Cas PO4> -£L& — mg/T
Q mg/1 Fiunrlde's (as F) .,. _ _-,-iTKJ/J
?.Q".mg/l Magnesium (as Mg) A1_ mg/T
Q_rng/T Iran (as F?) (T^t^i) ,,_ ,-^,.,rr- ,lr-r ..--.img/V
52.,.mg/1 Manganese (as Mn) _. ,-, _, , .mg /I '
220 mg /j Hardness (as '"aCOa) ,,,,..,..„ mg/i-
* .
RECOMMENDED STANDARDS' ..
Turbidity, not to exceed 10 mg/1 -
Color^ not- to exceed 20 ffig/1 •
No objectionable taste or odor , . . ..; '
'Iron aad sranganese together- should not" exceed 0,3 mg/1 ' ' " .
Magnesiun should, not exceed 125 mg/1 • • • ' -
Fluorides should not exceed 1,5 mg/1
Chloride should cot exceed 250 zng/1 . _ -,
Sulphate should not exceed 250 mg/1 ' ''*"';
Total Residue not to exceed 500 mg/1 for a water of good chemical quality. However,
if auuh water is not available, a total residue of 1,000 jcg/1 may be permitted.
Permissible pH about 10.6 at 26°C.
-------
NEW
f V DEPARTMENT OF>l]BLIC^'-*:Tir:V"-:"""?^';''"jt^;S^I^S
, I •_.,»_._-/>.— «.«* 1 L'rfenftflfinv* Co**** i *»»** . " . *' " *~ '
_«t¥ rroiHnental Sanitation Services
408 Gallsteo Street
Santa Fe, New Mexico
Dated _ ..March 29, 1961
The following chemical analysis based upon a sample of water recently submitted from your supply has
baen reported to us by the chemistry department of the State Public Health Laboratory* It is here-
with forwarded for your information.
TOWN
Grants
COUNTY Valencia
OWNER OF SUPPLY.
Homes take-Sapin
„ DATE COLLECTED
_ LAB NO.
3-8-61
POINT-OF nnrt.B/yrTON _ Prill Hole $14
RESULTS OF ANALYSIS
Color Units .
Odor, Nature
._TH. O
Temperatures : °C pH™.«*i.,_
Conductance 2.533. • Mleromhos /cm
. Total Residue S&3.Z mg/1
Non-filterable Residue _5§§ mg/1
^fe Filterable Residue 2Q49_ mg/1
Nitrates (as NOa).-—__J wg/1
Total Alkalinity (as £a£Qi) _~r_ mg/1
Carbonate iL.«,mg /I
Bicarbonate —, ±Jf* mg /I
Hydroxide . Q., mg /I
Chlorides (as Ct) 1QQ. mg/1
Sodium (as Na> 50§l._mg/t
Calcium (as Ca) -'
56
Sulphates (as SO*) 160° ^mg/1
Phosphates (as PG*) J
Fluorides (as F) —^.
Magnesium (as Mg)
Iron (as Fe) (Total) —
Manganese {as Mn) —
Hardness (as CaCOg)-
_rng/t
Remarks:-
RECOMMENDS} SIANDAHDS
Turbidity, not to exceed 10. rag/1 ....
Color, not to exceed 20 mg/1 ,
No objectionable taste or odor ' •
' Iron and manganese together should- not exceed p»3 aig/1 • . ;
J.uagnesium should not exceed 125 mg/1 • -.'.•••
Fluorides should not exceed l..fj mg/1 ' ' ' -
Chloride should not exceed 250 fflg/1
Sulphate should not exceed 250 mg/1
Total Residue not to- exceed 500 ag/1 for a water of good chemical quality.. However;,,
if such water is not available, a total residue of'1,000 fflg/1 may "be permitted..
Permissible pH about 10,6 at 26 C..
-------
NEW I^.V J DEPARTMENT OF PUBLIC
Environmental Sanitation Services
. - 408 Galisteo Street
Santa Fe, New Mexico
TH
Maroh 29, 1961
the following chemical analysis based upon a santple of water recently submitted from your supply has
been reported to us by the chemistry department of the State Public Health Laboratory, It is here-
with forwarded for your information.
TOWN
Grants
.COUNTY _ /Valencia^
OWNER Op SOPPLY Homes!taJce-Sapin
DATE COLLECTED _
LAB NO, '#32
nni,LP!f!TinN Drill Hole #13
RESULTS OF ANALYSIS
3-8-61
Odor Nattjrg* TH O
TurNfl'ty t- > • - . fng/1
Conductance .-£3»£ /yiicroifinos /cm
Total Residue . ^t*~ss . 'T1Q/"J
1 A A**
Filterable Residue;.., _ ."•'f- „ » m§ /I
K'tnarkf • ,
Nitrates (as NOs) ~
Total Alkalinity (as
Carbonate _
Bicarbonate
Chlorides (as Cl) _
Sodfurri (as Na)
Calcium (as Ca) .
" mo/1 Sy'ph»t«f {»» SO+), -Ci^Q^W/1
CaCOa) 203 mo/1 Ph"«ph»*«^ (« P<*H) 0.0~ mg/^
, , ,-- ,,,H,,,mg/l FlinjrHe* (^» F) , ,„..., ^n^/l
0 mo/I I«7n (as F*) (Tot3'} „.. x*"!/^
"l rr*-j . /ill yi
m^ .JT'^I ™fng/l f«ijr{<]dF!^5fi? (^^ r™ri) , .-. fc-_, ,,„,,, fTig /I
/ ^-Ox fnn /I H?**"drK%ss (as CaCOa).... ^.. ...... rng/l- •
269 ng'/i
BEOQUMEKDED STAHQfiHDS ' .
^Turbidity, not to eacceed 10 Eg/1 ' : _
Color, not to exceed 20 mg/1
No objectionable taste or odor1 . ' . • •
Iron and manganese- together, should not. exceed 0^3 mg/1
Magnesium should not exceed 125 rag/1 • -' "
Fluorides should not exceed 1.5 mg/1 . --
Chloride should not exceed 250 sng/1
Sulphate should not exceed 250 mg/1 ' :
Total Residue not to exceed 500 mg/1 for a water of good chemical quality. However,.
if such water is not available, a total residue of 1,000 rcg/1 taoy be permitted.
Pczsnicsible pH about 10.6 at 26°C. . • -.-';..
-------
st- r«;>^--
NEW
- ,
> DEPARTMENT OF PUBLIC Tw "TH
Environmental sanitation services
403 Galisteo Street
Santa Fe, Hew Mexico
JArch 29, 1961
The foilowing chemical analysis based upon a sample of water recently submitted from your supply has
been reported to us by the chemistry department of the State Public Health Laboratory. It is here-
with forwarded for your infcreation.
TOSH
Grants
COUNTY
Valencia
OWNER OP SUPPLY.
Homestake-Sapin
DATE COLLECTED
LAB NO. tf3
3-8-61
POINT OF nmj.ecTTQN Drill Hole |
BESULTS OF ANALYSIS
Color Units
Odor, Nature
Turbidity ™—
TH. O
—~ mg/1
Temperature *C pH—vLA.
Conductance _.-=£ZG. Mieromhos /cm
Tots?' Residue 9.4-.jJl£2. mg/1
Nort-filrerable Residue SQj.gSt.S.mg/i
RHeraWa Residue. ..§3.1._ mg/1
Nftrates (as NOa)
mg/1
~.
_?_5 — mg/1
____________ „.
Total Alkalinity {as CaCOaL 3.2JL_mg/ \
Carbonate- __ ,
Bicarbonate
Hydroxide _______________ Q __ mg /I
Chlorides (as Cl) ____ iQ9 _ mg/1
Sodium (as Na) _____ __3Q5_,jmg /I
Calcium (as C*) ________ . __ 3.3 ........ ..mg/1
SuIpHates (as SO4>-
-305-
-mg/T
Phosphates Cas PO4)—0-»D—.—mg/1
Fluorides (as F) , ___mg/l
Magnesium (as AAg) ^..1.0,. mg/1
Iron (as Fe) (Tofal) , mg/1
Manganese (as fAn) _— _mg /V
Hardness '(as CaCOg).. mg/T
Remark*:.
• RECOMMENDED STANDARDS -
Turbidity, not to; exceed 10 ffig/1 • •
CoIoT, not to exceed 20 ng/1 ' • .
No objectionable taste or odor :
Iron and manganese together should not exceed. 0.3 Wg/1 -
tegnesiiua should not. exceed 125 ffig/1 , .
Fluorides should not exceed "1. 5- Big/1
Chloride should not exceed 250 mg/1.
Sulphate should not exceed 250 mg/1 ' "
Total Residue not to exceed 500 mg/1 for a water- of good chemical quality. However,
if such water is not available, a total residue of 1,COG ng/1 may be permitted.
Permissible pK about 10,6 at 26°C,
.
b
-------
NEW
r^iyv'S^toSsgj
-•'.A. %3i^
.^O DEPARTMENT OF .PUBLIC Tit. .TH
Environmental Sanitation Services
" 408 Galisteo- Street
Santa Fe, Mew Mexico
Dated March 29. 196!
The following chemical analysis based upon a saitule of water recently submitted from your supply has
teen reported to us to the chemistry department of the State Public Health Laboratory. It is here-
with forwarded for your information.
Grants
.COUNTY Valencia^
Homes ta3ce-SaoliL
OWNER OF SUPPLY,.
POINT OP COLLECTTON Prill Hole |g
DATE COLLECTED
LAB NO, -
3-S-61
EESULTS OF ANALYSIS
-MrhMlfv ma /I
Total Residue ,*.Dj U&O __ mg/1
Mori-filterable Residue »)^ "lncj/1
Filterable Residue A-fS.. "»9/'
T» fRr»r}/-5 ; .. .. .
Nitrates (as NOa3 . -1 - rng/1
Total Alkalinity (as CaCOa)_14S — mg/\
Carbon9to V ^^ rn^/i
Rie^irhpriatB __ _ __ l^o mg/1
Chloridss £as Cl) „ ., . v,8S__rfi9/1
Sodium (as Ns) . ~ /U2 mp /i
Calcium (as Ca) — s.A±. mg/1
%
*
Sulphates (as SO*) !§50.. jng/i .-
•Phosphates (as PO4)~- *__Q-J=L,.— mg/1
FliiorW^* (^ F) -- -- n ' rnj/1
Msgnwi'jm (as MO) ,.3.55 .,,,;m(j/l-
Iron (rf5 Fp) (Tnfat) , ,„ „ IT'S /I
Mang?ne»e (a* Mn) - .- ..^^i,-,,.-, mg/*
H?rdnp« (a* CaCOg) ,-,^_, -fig/I
RECCUMENQED SIANDAHDS'
not ta- exceed 10 mg/1 •
Color, not to exceed 20 nsg/1 •
No objeeticriable taste or odor - •' • •
Iron and jranganese together" should not exceed 0.3 mg/1. •. •
l.iagnesiiun should not exceed. 125 mg/1
Fluorides should not exceed 1.5 mg/1 •
Chloride should aot exceed 250 mg/1 • • • " • .
Sulphate should rot exceed 250 ing/1 _ -;:
Total Residue not to exceed 500 mg/1 for a water of good chemical quality. However,
if such water is not-'available, a total residue of 1,000 sg/1 may be permitted.. . •
Permissible pH about 10.6 at 26°C. _ '
-------
.—£ T-V - - -.. -', ••--£-:
NEW MEXICO DEPARTMENT OF PUBLIC lh.'/,«
fH
Environmental sanitation services
408 Galisteo Street
Sauta Fe, New Mexico
Dated March 29, 1961
The following chemical analysis based upon a sample of water recently submitted from your supply has
been reported to ys by the chemistry department of the State Public Health Laboratory. It Is here-
with forwarded for your Information.
TOWN
Grants
..COUNTY
Valencia,
Hopes-talce-Sapin
OWNER OF SUPPLY
POINT OP rm.t.ggTtnN Drill Hole ^
DATE COLLECTED 3-g^
LAB NO.
.• #35.'
RESULTS Of ANALYSIS
Color
Odor,
_TH. O
.... °C pV
Conductance 2.QS.Q Micromhos/cm
To!sl Residue _253.§i,45.S _.mg/l
Non-filterable Residye ^,?.5.?_S2srng /I
Filssrabls Residua i42?_.... mg/1
Citrates (as NOa) D_«D mg/1
TotsI Afkalinity (as CaCO3)_228_mg/1
Carbonate . „ '. 13—rng/1
Bicarbonate _.
Hydroxide
Chlorides (as CD
Sodium (as Na) i_ -222, mg/1
Calcium (as Ca) .,____163__
-..fl-
ea
Sulphates (as SO4) —£°-Qi
Phosphates (as PO4)__—
Magnesfym (as Mg)
Iron (as Fe) (Total)
Manganese (as Mn)
Hardness (as CaCOa)-
-mg/1
_mg A
_rng/l
Remarks :-
BECQMUENDED ST1WD1EDS ' •
Turbidity, not to exceed 10 mg/1 " . • '
Color, not to exceed 20 icg/1
No objectionable taste or odor ' .
Iron and mangar.ese together should not exceed 0.3 jng/1
Magnesium should not exceed 125 ng/1
Fluorides should not exceed 1.5 mg/1
Chloride should not exceed 250 mg/1
Sulphate should not exceed 250 mg/1 • ' ' ' . •-
Total Eesidue not to exceed 500 rag/1 for a water of good chemical quality. However,,
if such water is not available, a total residue of 1,000 Bg/1 may be permitted.
Permissible pH about 10.6 at 26°C.
-------
NEW Kte ) DEPARTMENT OF PUBLIC
Environmental sanitation Services
408 Galisteo Street
" ' Santa Fe, New Mexico
Dated I^rch 29, 1961
The following chemical analysis based upon a sample of water recently submitted from your supply has
been reported to us by the chemistry department of the State Public Health Laboratory. It is here-
with forwarded for your information.
TOWN
Grants
.COUNTY
Valencia
OKNEE OP
Homes take-Sapin
DATE COLLECTED
LAB NO. Jr34:i..
POINT OP COLLECTION,
Drill Hole
RESULTS OF ANALYSIS
Color Units
Odor, Nature
Turbidity — i
.TH. 0.___.
„ mg /I
-c PH..JL4._
Temperature „ ,—,„ _ ,_
Conductance ..188.9 Micrsmhos/cm
Total Residue ..5270 mg/I
Non-filterable Residue ...§302—mg/1
rilt-srable Residue 2.?r_ mg/1
Nitrafes {as NOs)
.y^.2 mg/1
Alkalinity (as CaCOa)_392L_mg/V
Carbonate , • fi.,_mg /I
Bicarbonate . 3Si mg /I
Hydroxide , 9....mg /I
Chlorides (as Ct) „_ __2Sfi, _mg/l
Ssdium (as Na) 2Aa-.._
Calcium (as Ca) ,.2Z mg/1
Sulphates (as SO^) 33,
Phosphates (as PO4> .O...Q,
Fluorides (as F) _,
Magnesium (as Mg)
Iron (as Fe) (Total) .
Manganesa (as Mn) _ .
Hardness (as CaCOa) -
Remarks: -
RECOMMENDED SXAHUfiEDS
Turbidity, not to exceed P rog/1 '
Color, not to exceed 20 mf/1
No objectionable taste or odor
Iron and manganese togetler should not exceed 0.3 mff/1
tegnesiunt should not exceed 125 rog/1
Fluorides should not exceed- 1,5 mg/1
Chloride should not excsed 250 mg/1 • .
Sulphate should not exteed 250 ng/1 _ ;
Total Residue not to ccceed 500 mg/1 for a water -of good chemical, qualiigr. However,
if such water is not ivailable, a total residue of 1,000 Eg/1 may Tje permitted.
Permissil)_3 pH about 10.6 at 26 C.
-------
-ICL..I
,0 DEPARTMENT OF PUBl
Ehvlrcnaental Sanitation services
408 Galisteo Street
Santa Fe, " New Mexico
mi
Dated'.
May
- 1962
The following chemical analysis based upon a sample of water recently submitted fron your supply has
been reported to us by the chemistry department of the state Public Health Laboratory. It is here-
with forwarded for your Information.
T01fi Homes take-Sapin Mil ..COUNTY Valencia
OWNER OP
Homes take-Sap in
DATE COLLECTED
LAB NO. 331
v'n^l&ifr *"**• *«* v* * • •mi a a run i ^^^^^^^—^^^^^^^— ^__^________^______ f\
POINT OP pftt.T.fp.TTQN Observation Well -just off,.S£_ corner of tailings pond , ffi L ;
RESULTS OF ANALYSIS
Color Units
Odor, Nafu
Tn'tuV'iv
Total Rssidi
Nonfilfere
Nitrates (as
eolprless.pH 7.* 3...
re normal Tk O- - -
01 ear
e 2S°C 199(J/ticromb
1580
Us Residue ..
ResMue 1580
NOil • 11 . .
mg/l
mg/l
.mg/I
mg/1
mg/l
Total Alkalinity (as Ca(
Cafborto'e
Bicarbonate
Hydroxici©
Chlorides (as C\]
Sodiurn (as Na)
Calcium fas Ca)
Sulphates [as SCU
6.6
176
0.0
89
228
iffd?"
mq/l
mg/l.
mg/l
mg/l
mg/I
•mg/l
Potassiym |
Fluorides [a
Magnesium
Iron (as Fe]
Manganese
Hardness (t
Surfactants
as K) .. .
s F}
(as Ma) .
(Total) ...
(as Mn] .
ss CaCO»
{as ABS] -
3.9
0..8Q
41
0.03
0,00
] 680
< 0,05
. mg/!
mg/l
™_ mg/l
mg/l
mg/l
,„, mg/I
..... mg/l
n^,^..
I . •
STANDARDS
Turbidity, not to exceed 10 mg/l •
Color, not to exceed 20 mg/l
No objectionable taste or odor
Iron arid manganese together should not exceed 0,3 mg/1.
Jfegnesium should not exceed 125 ng/1
Fluorides should not exceed 1.5 mg/l
Chloride should not exceed 250 mg/l
Sulphate should not exceed 250 sng/1
Total Residue not to exceed 500 mg/l for a water of good -chemical quality. However,
if, such water is not available, a total residue of 1,000- fflg/1 may be permitted.
Permissible pH about 10,6 at 26°C.
-------
NEW
c
^0 DEPARTMENT OF PUBLIC"!-..
Environesental £aciCation Services
403 Galls tea Street
Santa Fe, New Mexico
-TH
24, 1962
Ths following chemical analysis based upon a sample of water recently submitted fro,n your supply has
been reported to us by the cheaistry department of the State Public Health Laboratory, It is here-
with forwarded for your inforraation, ' -
TOWN Hoagstake-Sapin Mill. COUNTY
OBNSR 0? SUPPLY ... Homestake-Sapin
yiaencia
DATE COLLECTED
LAB HO. 333
5-4-62
POINT OP (*rn.T.FnTTnN Observation Well .fust S*f of tailings pond
Or
RESULTS OP ANALYSIS
r*«i«r ifnitc col ni*1 ess nH ?BS
O"*or Naiur<=" HOTHS.! Th O
Turbidity Clear mg/!
Cor>d'jri""i'~= 25sC2525tvlicromhos/ciTi
T_*,I Pajtdus 2150 mQ / 1
WUi^l-Ar^Mp' Rocirlup J-*' mn/i
Filfe-ab'* Residue 2140 mg/l
N>tr*t">s {as NOj1 ^?. ., - mg/ 1
Remarks;
Totol Al^sitnitv (as
Oarbonst©
Bicarbonafe
Hydroxide ..
Chlorides (as Cl] .
Sodium iss r4aj
Calcium fas Ca) ...
Sulphates (as SO.i)
CaCQ3}203 mg/I
0.0. mg/I
2Q3. mg/i
.... . 0.0. mg/l
, 1Q8.. ..mg/l
256 mg/|
^JlC mg/l
(^1562^ mg/|
^d — ---^
Potassium (as K] ...... ,...9.6
Fluorides fas F) P..,5Q....,
Magnesium (as Mg) ...JPP.
Iron (as Fe] Tots!) .......ft,!.°,l.,.
Manganese, [as Mn} _._9..r,5P, —
Hardness (as CaCO3) .ICiQQ
Surfactants [as ABS] <.Q.,.QS.,...
.. mg/l
.. mg/l
.. mg/l
.. mg/l
„ mg/l
.. mg/I
.. mg/I
RECOMMENDED ST1NDA1DS
furbidity, not- to exceed 10 mg/l •
Color, not to exceed 20 nsg/1
No objectionable taste or odor . . .
Iron and irangaiiese together should not exceed'0.3 ffig/1
Magnesium should not exceed 125 ffig/1
Fluorides should not exceed 1-5 rog/1
Chloride should not exceed 250 mg/l
Sulphate should not exceed 250 mg/l . - 1
Total Residue not to exceed 500 mg/l for & w.ter of good chsaic,al quality. However,
if such water is not available, a total residue of 1,000 125/1 may -be pezmttted.
Permissible pH aoout 10.6 at 26°C. , '
-------
-
r
NEW
y> DEPARTMENT OF PUliLl
..iivironaental SauUation Services
403 Galisteo Street
Santa Fe, New Mexico
Dated..
fey 24, 1962
The following cheElcal analysis based upon a sasple of water recently 'submitted from your supply has
been reported to us bp the cheroistry department of the State Public Health Laboratory. It Is here-
with forwarded for your information.
TOWN
Hoaestake-Sapin Mill COUNTY _.. Valencia
OWNER op SUPPLY..
DATE COLLECTED ?-4_-62
LAB MO.
POINT.OF r"t-LggriQN South Observation Well
0
RESULTS OF ANALYSIS
Color Units...Colorless,..pH....7",6.."..
Odor, Nature .Normal Th. O
Turfaidify Clear mg/l
Conductance 25cCl665.Micromhos/cm
Tofa! Residue mg/l
M --'is- r*™! !<<=-;-l-'A r"a/l
)4 FHfsroble Rss?aus . .. 1310 mg/|
.25..,_. mg/t
siraiss las
Total Alkalinity (as
Carbonate .Q-.O. mg/l
Bicarbonate , .3$4 mg/l
Hydroxfde .-. .Q.-..Q. mg/l
CHcrrdw {as C!) AO - ..mg/l
Scd?um (as Na] , *D5. mg/l
> i -\ S i~t
Calcium (as Ca) ..„...„ •^4§^v m<3/1
Sulphates
..1,9...
0.80
Potassium (as K]
Fluorides {as F).
Magnesium (aa Mg] .....Sz — rng/t
Iron (aa FeJ fTota!) 0...19 sng/l
Wanganes& (as Mh)_ P.s.w!v. — mg/l
Hardness (as CaCOj) ....5^?. _ irig/F
Surfactants (as ABS] ...f
mg/i
Slight yellow brcr.'m sediraent
• . KECGJ-fiffi-IDED STANDARDS.
Turbidity, not to exceed 10 mg/l
Color, not to exceed 20 Eg/1
Ho objectionable taste or odor
Iron and Esnganese together- should not exceed 0.3 ng/1 • '
Ifegnesius should not exceed 12.5 mg/l - - •
Fluorides shculd. not exceed 1.5 rag/1 ' ' - .
Chloride should not exceed 250 Eg/1
Sulphate should cot exceed 250. ffig/1
'Total Residue not to exceed 500 mg/l for a water of good chemical quality. However,
if such water is not available, a total residue of 1,000 ing/1 aay be permitted..
Permissible pH about 10.6 at 26 C.
-------
-^X v
FHOGHESS REPORT'ON GOHI&gMATIOH ''W* '
eg POT&BIB GBOUKD HATER IH THE GHAHT3-BIBEtfATEa AREA,
IKTEODUOflOH
The uranium ore processing mills of Homestake-Sapin Partners and Homestake-
New Mexico Partners .are Heated on adjoining properties in the north half and
south half, respectively, of Section 26, Township 12 North, Range 10 West, ia
Valencia County, New Mexico. .Ore for these mills is extracted from mines in the
Ambrosia' Lake-Haystack Butfce area north of the millsites. -Disposal of process
water from the two laills is effected into two unlinfd. surface -ponds. The maximum -
surface area of these ponds is approximately 62 acres and 41 acres, the larger figure
the ' .- ,.,..---"•" ": "'" " """"--•..
f, \ being for the pond of/Hbmestake-Sapin Partners mill, / The rate of discharge of effluent
/\
V into either pond per unit of area 'of the pond is considerably more than the normal
-
rate of evaporation in the general area of the mills. So far as is ssac known, the
ponds have never been filled to overflowing, therefore, under existing conditions
, _ it must be assumed that the part of the effluent not being evaporated is seeping into
, \ porous alluvial materials upon which the ponds have been constructed. ..- -
In the spring of I960 the New Mexico Department of Public Health, in cognizance
of the potential hazard of downward percolation of mill effluents from these ponds^. k.
^ .ipj^xv; ^ , - Xc, -^ ^ "^
*he~is«4deac.e-^f--r^ioacM-ve-^on%52iination-i3i „.
# + .f '/s - - ~~ /••' x^^.^^;:^,.^^
-S
A
'^>
r'r.
^"T*"'^'" " -«-—-» L-*-*-«-
-------
potailg grnaafr-haLera1. .^rLufe lu Ilia alluuluau "Sabawj-autly, during the period
of June 6 through June 9, I960, twenty exploratory holes were drilled to determine
' .
the character and thickness of the alluvium and the configuration of the upper surface
of the underlying bedrock. This drilling was accomplished with rotary tools using
compressed air as a circulating median whenever possible and water whenever necessary.
fhe work was planned, directed, and paid for by the two companies concerned and witnessed
by geologists of the U. S. . Geological Survey and the State Engineer Office. Samples
^
of cuttings obtainfd froa these test holes were collected and examined by ibis writer.
Eight of the twenty holes drilled were cased with two-inch steei pipe and retained
as monitor wells* " , •- "
'' ' •+''''
This report present^ and evaluate^ the results of the exploratory drilling
Mim ?/
program and data obtained from the monitoring program through -Haye* $ft 1961. The
topography of the investigated area, the location of local water wells, and the
location of exploratory holes referred to in this report with respect to the location
of the mills and their disposal ponds are shown on Figure* i^-*t
-------
stock, and irrigation use* Uneonformably underlying the alluvium are red silty
claystones and silty fine-grained sandstones comprising the Ghlnle formation of
Triassic age. In the irf.ninity of the mills the Chinle formation is approximately
4.00 feet thick but because of low permeabilities it yields water sufficient in
quantity only for limited domestic and stocft use. Immediately underlying the Ghinl*
formation are the San Andres limestone and the Glorieta sandstone of Permian age.
These lot-tag formations have thicknesses of 75 and 100 feet, respectively, and
constitute the principal aquifers from which water is nkygtx obtained for the towns
*^r~*- ,*•**—^f»«uc*«^«» «>5j ' . ' " J
of Grantsjarid San Rafael, tho trhiCTm+nT T^IT.^ and .the uranium mills cf the Anaconda
.__, Homes tske-Sapin Partners, and Homestake-Bew Mexico .Partners,
Lithologie descriptions and other basic data relating to the character of the
materials encountered in the alluvium and the upper part of the Ghinle formation
during the drilling program at the millsites are appended to this report. Figures
. 2 and J show the altiduid and configuration of the Qhinle formation and thickness
of the alluvium, respectively, as indicated by tfeee-etest holes an4 other available
subsurface data in the vicinity of the millsites* [The San Andres limestone and
Ithe Glorifeta sandstone are of relatively little importance to the immediate problem
V
/ of ground-water contamination in the general area of the subject mills and have /
/
not been studied as a part of this investigation.
-------
TABLE
Depths to water were measured by this- writer on June 15 and 16, I960, in
each of the ei^ht exploratory holes retained as monitor wells. A tabulation of
these data is as followst
Monitor
¥ell yp.
6*-
8-'
9-
10
ISv-
19
20
Land Surface
Altitude
6580
6575
6583
6586
6576
6565
6568
6564
Depth to Water
Below Land Sur^
53.00
55.52
dry
53.86
61.65
63.30
bridged
60,75
Water Level
Altitude
6527
6519.48
6532.14
6514.35
6501,70
6503.25
Bats of ^
6-16-60 (*-?•
6-16-60 ,-.-•
6-16-60
6-16-60 •:•>"'"*•
6-16-60 '-': *
6-15-60 : '" ' ''
6^15^0
6-15-60 '--•"'"•
The altitude and Configuration of the water table ia the vicinity of the
mill sites, as determined from thase localized data, is shown in Figure 4* '
CHMIC1L QM11TI OF GEOUMO-
SUPPLIES
Fourteen aamples of water have been collected from ground- and surface-water
sources in "the general area of the Homestake mills by personnel of the State Dep-
artment of Public Health, The Homestake-Sapin Partners, and the State Engineer
Office during the course of this investigation. The results of laboratory analyses
of these samples by the Arizona Testing Laboratories appear in Table QJT
-------
Y *
,—^ *"s,
^ E^TOAOTIYIIT OF SHALLOW G. _..B-W£J?ER SUPPLIES
Samples of water for radioactive analysis were collected from I wells No. 5,
6,9, and 10 in Angust I960 by tl»4s- writer and Mr. DeJong, chief metallurgist for
Homestake-Sapin Partners. Analyses of these samples by the Robert A. Taft Sanitary
Engineering Center at Cincinnati, OMo, show the following concentrations of ladiun 226s
Point of collection jaaG Ha/liteer
Monitor well Ho. 5 .1.8 . .
Monitor well No. 6 0.7
Monitor well No. 9 "" 0.8
Monitor yell Ho. 18 3.1 .
The normal background radiation for ground-water occurring in the Ogallala formation
t/
of eastern Ifew Mexico ranges from 0.1 to 0.8 micromic&i|euriea per liter with a
median of 0.1 micj^inic^curies of radium per liter fyyaS Ha/liter^. Concentrations
of uranium in water from the Ogallala foimatidn ranged from 0.9 to 12 parts per
billion (ppb) with a median of £ZZ 6.2 ppb. The|e concentrations are relatively
high compared to the uranium content of 67 random samples from fluviatile sedimentary
aquifers throughout the United States. .The .uranium concentration in these random,
samples ranged from 0.1 to 22 gpb with a median of 1.6. ppb or .0016 parts per millioa,,
J? Barker, F. B., and Scott, I. 0., 1958, Uranium and radium in the Ground Water
of the Llano Estacado , Texas and Mew Mexicoi 1m. Geophys. Union Trans., v. 39,
p.. .459-466. ' ._ .
The sfesiee spread of radioactive incidence, 0.7 to 3.1/pC la/liter in monitor wells,
G .
is probably caused by local anomalies in stratification affe/ting the lenticular!ty,
-------
.
porosities, and permeabilities within the ^^und^water body which subsequently
affect the direction of groandwater movement and longevity of the presence of
certain radioactiyely charged groundwaters at successive downgradient locations
within the specific aquifer..
Well No. 18 with the greatest oceurrnce of radioactive material Is locally
/ "-'•*•
downdip from the Homestake-Ifaw Mexico Partners tailings pond^/but only if one traces /
an imaginary line connecting the pond to the well wb|Cg)h actually would follow the /
'
. . ,
/ approximate axis of 'the southwest-trending nows shown in Figure 2,/Sef erring to
-------
*—^v A j>
~ • . ) p. 6
Figures 2 and 3, Uell No. 6, with the least occurrenca of rdaioactive material,
might have been expected to «w a higher incidence as it is directly dowa-structurs,
on the Chinle surface^ from the ffoipstake-New Mexico Partners pond fanfflapprraciaately \
( on horizontal strike with planes that literally circumvent the Homestake-Sapia
tailings pondJ^WeHsS and 9, on the other hand, are decidedly up-structure from
the Homestake-Sapin pond with respect to tie aeaaJaMgb1 Chinle surface. . ,—
In all f airmess to the uranium mill operators, a test for radioactive eontaminatioa
of strata communicable with near-surface seepage should include a control wherein
resulting incidence of radioactivity would be nil or correlative with normal back-
.r '
ground radiation for the area in question. Provisional records of the Quality of
Water Branch of the U. S. Geological Survey indicate that the radium content of
wateri from selected sources in Xffl MoKinley and Valencia Counties may range from
*••"%
less than 0.1 micro^microcuries per liter, Bluewater lake surface water, to 42
.
mici^toicrocuries puexijufcjg: per lifcer, mine drift water of the Westwater Canyon
(fable 3 lists radiological data from waters in"
Mclinley and Valencia Counties, Hew Mexico.)
sandstone which is mined for uranium,/" This rate of increase in content of radium
in waters from surface sources pprgressively deepening to the actual uranium-bearing
horizons is readily obvious and apprehendible. fable 4. is a preliminary compilation
of natural dissolved radium content of surface waters northwest of the Grants-BluewaseT1
-/ - area. This data was compiled by the U. S..Public Health Service and is Included merely
as related background radiation material of the general area.
-------
i
'Accepting radial seepage of. mill waste waters into & iensing aquifer, the
/ foregoing results of analysts, for Sadium 226. are indicative of definite pollution
of the shallow groundwater bj the effluents5 and this radial seepage may account
for the incidence of radioactivity in waters collected from monitor walla 5 Mnfl 9»
The. writer recognizes the fact that monthly-reports are submitted by the two
c
mill operators concerning data of tailings pond waste disposal to the Environmental
Sanitation Services of the lew Mexico Department of Public Health.
Notwithstanding the fact that Homes take-New Mexico Partners has undoubtedly
gone to great pains and some expense in setting up measuring equipment and devices, •.
the data submitted in monthly reports by this operator are inconclusive and misleading
to the reader. They are presented by inventory methods using metfcred volumes and
surveyed (calculated) volumes of miji. waste waters as two systems of analysis, and
leaving too much to the reader's imagination. Hot being a statistician or a research
analyst this writer cannot fully appreciate the value of" these data as presented.
The data submitted by Homestake-Sapin Partners are presented by the method of
1 accountability whereby the end result is a volume of mill, effluent accounted for or
i unaccounted for and this presise information is more readily assimilated.
CONCLUSIQHS
One cannot expect an erratic and leasing aquifer such as the shallow Quaternary
alluvium.to be competent enough stratigraphically to follow an ideal hydraulic pattern
-------
p. 8
that might coincide with that of adjacent horizons. la fact, it is reasonable to
assume that the regional interformatlonal direction of flow in more competent beds
is actually trending to the north and northeast into the San Juaa Basin.
B2GQMMEHDAIIONS
It is hereby recommended that additional and more widespread sampling be
. ai
performed in an effort to determine further radioactive pollution of Quaternary
i*
alluvial aquifers as opposed to natural background radiation of this currently
prolific uranium-producing region.
\Eugene A. Chavez£ geologist
Technical Division, State Engineer Office
Roswell, New Mexico
April 3-» 1961
-------
Technical Assistance Services for Communities
Contract No.: EP-W-07-059
TASC WA No.: R6-TASC-002
*„.,• aol *** Technical Directive No.: R6-Homestake Mining-02
Observations and Recommendations Regarding the Draft Focused Review of Specific
Remediation Issues for the Homestake Mining Company (Grants) Superfund Site,
February 2010 - Ground Water Considerations
May 6, 2010
Prepared by Wm. Paul Robinson and Chris Shuey
Southwest Research and Information Center
Introduction
This document provides the Bluewater Valley Downstream Alliance (BVDA) with observations
and recommendations based on a technical review of the "Focused Review of Specific
Remediation Issues: An Addendum to the Remediation System Evaluation (RSE) for the
Homestake Mining Company (Grants) Superfund Site, New Mexico," a February 2010 Draft
Report prepared by the U.S. Army Corps of Engineers' Environmental and Munitions Center of
Expertise for the U.S. Environmental Protection Agency (EPA), Region 6.
The Draft Report is hereafter referred to as the "DRSE Report." The DRSE Report's scope of
work, conclusions and recommendations are included as Appendix A. An overview of the
remediation system at the Homestake Mining Company (HMC) site evaluated in the DRSE
Report is provided in the November 2009 "Summary and Review of Application for
Modification and Renewal of NMED Discharge Permit DP-725, Effluent Disposal Facilities for
the Ground Water Remediation System at the Homestake Mining Company, Grants
Reclamation Project, Milan, N.M. ["TASC Report"], among other sources.
This document addresses the following topics covered in the DSRE Report:
A. The burden of uranium and other contaminants in HMC tailings.
B. Monitoring well effectiveness and location.
C. Over prediction of flushing performance.
D. Identifying accurate ground water conditions in the Middle Chinle aquifer.
E. Life-cycle cost and effectiveness of remediation options identified.
F. Spray evaporation as a variable in determination of evaporation performance and
evaporation options.
G. Remediation cost recovery.
H. Distribution and review of a revised DRSE Report for comment before completion of a
Final RSE Report.
-------
DRSE Report Observations and Recommendations
A. The Burden of Uranium and Other Contaminants in HMC Tailings.
Observations
The DRSE Report confirms concerns that the HMC remediation system has not effectively
reduced the mass of uranium present in the tailings in the three decades since its inception,
including the decade-long flushing program. The DRSE Report focuses heavily on uranium as
an indicator of contamination and remediation with little discussion of other constituents of
concern.
A reasonable approximation of the uranium remaining in the tailings is useful in assessing
remediation performance and in the modeling and evaluation of future remedial options and
actions. Bluewater Valley Downstream Alliance (BVDA) remains concerned, as expressed in
comments on the 2009 Draft RSE (prepared by a different EPA contractor) that the DRSE
Report significantly underestimates the remaining uranium in the tailings and therefore both
underestimates the remaining burden of uranium in the tailings pile and overestimates the
effectiveness of uranium removal in the HMC remediation system.
The DRSE Report at p. 6, sec 2.1.1 states, "Assuming the ore had an average of 0.15% uranium
content and that the tailings had an average of 0.006% remaining uranium (based on
information in [EPA's TENORM Report Vol. 1.] EPA 402-R-08-005, Table 3.13), the
22,000,000 tons of tailings would contain approximately 2.6 million pounds of uranium, or
approximately 2.5 times the amount estimated to have been removed during the clean up effort
through 2008."
The assumption of 0.15 percent uranium content in ore and 0.006 percent concentration of
uranium remaining in the tailings assumes 96 percent recovery of uranium by mill operations
with the remaining 4% being disposed of in the tailings piles (0.006% = 4% of 0.15%) and that
each one percent of the uranium in the ore that remains in the tailings is equivalent to 660,000
pounds of uranium.
The assumption of 96 percent recovery of uranium cited in the DRSE Report is likely to over-
predict recovery of uranium from mill operations at the HMC site, as it is higher than the
uranium recovery rate reported for the specific mills on site or other uranium mills operating in
New Mexico. Sources reporting on the HMC site's mill operations directly indicate higher ore
grade and uranium content in tailings information than the more generic, non-site specific
source cited in the DRSE Report.
The estimate of uranium remaining in the tailings in the DRSE Report is within the same "order
of magnitude" as those identified in sources reporting data from the HMC site mills. However,
the DRSE Report estimate is likely to be low by a factor of 2-3 or more from the actual amount
of uranium in tailings if the HMC site-based sources are used. The low remaining uranium
burden estimate in the DRSE Report therefore is likely to significantly overestimate the
-------
effectiveness of the HMC remediation system's uranium recovery efforts by a similar factor of
2-3 beyond the actual effectiveness of uranium recovery vs. uranium remaining in the tailings.
Sources of ore grade and uranium recovery information derived from HMC site mill data
include:
1. New Mexico Bureau of Mines and Mineral Resources Open File Report 25: United Nuclear-
Homestake Partners Uranium Milling Operations, Grants, New Mexico, 1968 ("OFR-25"),
at http://geoinfo.nmt.edu/publications/openfile/downloads/OFR014-99/14-25/25/ofr_25.pdf.
OFR-25 reports that in the 1960s, the UNHP mill at the HMC site operated with "grade of
the ore averages [of] 0.21% U308 and the leach residue averages [of] .011% U308."
Assuming that "leach residue" is tailings, OFR-25 reports a 95 percent uranium recovery rate
but 33 percent richer ore on average than the DRSE Report and almost twice (183%) the
residual concentration of uranium in the tailings. Use of the higher grade and higher tailings
uranium content data from OFR-25 would result in the uranium burden in the 22,000,000 tons
of tailings at the HMC site of 4.8 million pounds. This amount of residual uranium is 4.5 times
the approximately 1.1 million pounds of uranium recovered by the HMC remediation system, as
the amount of uranium recovered would fall to only 23 percent of the uranium mass remaining
in the tailings after cessation of operations from the 41 percent assumed in the DRSE Report.
2. "Process and Waste Characteristics at Selected Uranium Mills" 1962, U.S. Public Health
Service Report W62-17, cited at p. 12, November 2009 "Summary and Review of
Application for Modification and Renewal of NMED Discharge Permit DP-725, Effluent
Disposal Facilities for the Ground Water Remediation System at the Homestake Mining
Company, Grants Reclamation Project, Milan, N.M. ["TASC Report"] report of a 90%
uranium recovery rate was attributed to the uranium mills operating on the HMC site in the
late 1950s and early 1960s with an average ore grade of 0.15 - 0.2.
If the recovery rates in the USPHS Report are accurate, the amount of uranium remaining in the
tailings would approach 6.6 - 8.8 million pounds and the percent of uranium mass recovered
since HMC remediation began falls to the 12.5 percent to 16.7 percent of original uranium
content in the tailings.
3. "New Mexico Energy Resources '81: The Annual Report of the New Mexico Bureau Mines
and Mineral Resources, at http://www.osti.gov/bridge/servlets/purl/5391358-
krD4W575391358.PDF, reported that, in 1980, operating uranium mills in New Mexico
recovered "92 percent of contained U308 from ore in mill-feed operations."
If the DRSE Report assumed a 92 percent recovery rate rather than a 96 percent recovery rate
for uranium for mills operating at the HMC site, the amount of uranium remaining in the
tailings would double, and the percent of uranium recovered would fall by 50 percent.
-------
Recommendations
The DRSE Report should be revised to present a higher estimate of uranium remaining in the
tailings following mill operations. The estimate of uranium in the tailings piles should be
revised upward by at least 100 percent, to the 4.8 - 6.6 million pound range, based on available
technical literature reports addressing uranium remaining in tailings from the HMC site mills.
To the extent that one of the goals of the HMC remediation system is recovery or stabilization
of the mass of uranium in the tailings, it seems to be extremely important to establish a
conservative estimate of the baseline of uranium in the tailings based on site-specific data. Such
an estimate is likely to be at least twice the estimate of uranium remaining in the tailings in the
DRSE Report.
Though not a concern identified at the beginning of the RSE process, the DRSE Report should
be revised to address HMC's technical approach, which emphasizes removal of uranium in
solution in the tailings and considers the uranium not in solution to be relatively immobile and
not likely to leak out of the tailings.
The DRSE Report should be revised to address, or comment generally on, the likely distribution
of uranium remaining in the tailings between portion of uranium that may be dissolved in
liquids in the large tailings pile and the remaining uranium not dissolved in liquids. The DRSE
Report should also be revised to evaluate the effectiveness of the HMC remediation system to
recover either or both portions of uranium remaining in tailings.
B. Monitoring Well Effectiveness and Location
At p. 14-15, the DRSE Report identifies elevated uranium concentration in wells DD and SI 1
on the west side of the large tailings pile. The elevated levels of uranium in these wells provide
the basis for the DRSE Report's recommendations to:
1) "Further evaluate capture of contaminants west of the northwestern corner of the large
tailings pile."
2) "Consider background concentrations of uranium in assessing site strategies for the
alluvial aquifer."
1. Data presentation and reporting
Observations
The DRSE Report does not identify or discuss any of faulting and fracturing in the structures
west of the large tailings piles and their potential influence on ground water quality, ground
water flow rate or ground water flow direction in the graphic or narrative portions of the DRSE
Report.
-------
Figure 1 at p. 9 is not sufficiently detailed to identify the location of the wells of concern
discussed in this section, as well as other sections of the Report. Figure 1 does not identify the
locations of wells DD or SI 1 or the flow paths of concern on the west side of the tailings pile.
The figures that do illustrate the concentration vs. time plots have a wide variety of scales that
prevent an effective comparison of the data reported. Recognizing that the data for the wells has
been entered into a "excel" spreadsheet should allow a revised DRSE Report to include more
illustrative graphs and charts.
Neither Figure 1 nor other figures identify the location of fault zones in the project area, the
extent of the alluvial aquifer, or other geologic features that might influence ground water flow
paths on the west side of the large tailings pile. The "scanned" well location maps posted by the
RSE contractor team on the FDVIC RSE Quickr website provide additional detail but are not
clearly integrated into the DRSE Report.
Recommendations
The graphics in the DRSE Report should be enhanced to identify key locations such as wells
and pond sites, identify key geological and land use features, and provide more readable graphs
of contaminant concentrations over time so that vertical scales are similar, rather than a
selection among arithmetic and logarithmic scales, and check that the dates for data reported are
readable.
2. Monitoring well DD and its associated potential ground water flow path
Observations
The DRSE Report shows a rising uranium trend in well DD in Figure 13 which results in a
doubling of the uranium concentration in that well from the initial data point, which appears to
be from the 1970s. The DRSE Report recommends the adoption of efforts to "further evaluate
capture of contaminants west of the northwestern corner of the large tailings pile."
Recommendations
The DRSE Report should be supplemented to identify methods or techniques to identify and
address a potential flow path in the area of those wells west and north of the large tailings pile.
The DRSE Report should be supplemented to identify specific additional investigations, such as
borehole installations, non-intrusive geophysical methods, ground water control systems or
other measures to identify and address the flow path in the well DD and SI 1 area.
The DRSE Report should be supplemented to include an assessment of the effect of the
consistent rising trend in uranium concentrations in well DD on the value of a well at or near the
location of well DD as the single down gradient monitoring well for ground water conditions
for proposed pond EPS.
-------
The DRSE Report should be supplemented to address the location of well DD and its associated
flow path within the footprint of proposed evaporation pond 3 (neither well DD or EPS are
identified on Figure 1) and the challenges to investigation and remediation of the ground water
with rising uranium content in the well DD/well SI 1 area north and west of the large tailings
pile.
The DRSE Report should be supplemented to address the extent to which the elevated uranium
in wells DD and SI 1 and the flow path that may be associated with them occurs under or down
gradient of proposed pond EPS. Illustration of the location of wells DD and SI 1, the extent of
fault zone on the west side of the large tailings, the extent of the alluvial aquifer and proposed
location of EPS would demonstrate the relationship of these features at the site.
The DRSE Report should be supplemented by the identification of recommendations regarding
future investigations to determine variations in ground water flow rates and the pattern of
contaminant concentrations in the fault zone on the west side of the large tailings pile compared
to less fractured portions of the aquifer occurring in that fault zone, to define the ground water
flow path in that area.
3. Capacity of well X to monitor for uranium in pond or tailings seepage compromised
due to the influence of nearby wells used for injection of clean water
Observations
The DSRE Report's Adequacy of Plume Capture section states, at p. 8, that "Ground water
concentrations of uranium and selenium in the alluvial aquifer in the vicinity of the small
tailings pile have been significantly reduced (such as well X, a compliance point), though some
wells have persistent concentrations well above the cleanup goals as represented by the plot of
uranium for well K4."
Figure 3 on p. 8 illustrates the downward uranium trend in well X.
Of the hundreds of borehole completions on the FDVIC site, only two boreholes, monitoring
wells X and DD, are completed in the configuration and in location that allows them to be
designated as and function as monitoring and/or compliance wells...
Review of the uranium concentration trend for well X in Figure 3 shows that the uranium
concentration in the well remained relatively steady for several decades before a steep drop in
uranium concentrations was detected.
Figure 3 shows the drop in uranium concentration occurring after the construction of EP1 and
the injection wells - including the "1993 J-line" of injection wells - along the south perimeter
of EP1 and the small tailings pile. Figure 1 shows well X to be in such close proximity to
injection wells that the symbols for the two are touching on the figure.
-------
Review of the "Concentration Trends" spreadsheet prepared by the RSE Contractor team
identifies the specific time when water quality changed dramatically in well X. At the March
28, 1994 sampling, the uranium concentration fell 90 percent from the previous quarterly
sample: from 11.55 ppm in the November 3, 1993 sample to 1.19 ppm in the March 28, 1994
sample. Sulfate concentrations in well X dropped from 3,312 ppm to 978 ppm during the same
period.
From the data in the "Concentration Trends" spreadsheet, the point in time when well X began
sampling injection water rather than the alluvial aquifer is easily identified.
Though the DRSE Report documents a significant decrease in uranium detected in well X, it
does not include a discussion of the likely influence of the injection of clean water in close
proximately to well X on uranium concentrations in that well or its potential to monitor seepage
from tailings piles or ponds on the HMC site.
The DRSE Report takes the data from monitoring well X at face value and does not identify the
volume, quality or duration of clean water injected into the alluvial aquifer from the injection
wells in close proximity to well X. The DRSE Report does not attempt to correlate the degree in
uranium concentrations in well X with the use of the injection wells.
Recommendations
The DRSE Report should be revised to include recognition of the extensive injection well
operation within a few meters of monitoring well X and the "almost instantaneous change" in
uranium and sulfate concentrations in that well in 1994 when the injection system began.
The DRSE Report should be revised to reflect the likely effect of these long-term injections of
clean water on the uranium concentrations in well X. The DRSE Report should also be revised
to address the data in the "Concentration Trend" spreadsheet as a demonstration that the
reduction in uranium concentrations in well X is attributable to dilution resulting from injection
of clean water rather than demonstration some sort of reduction in uranium concentration due to
uranium removal or control in the alluvial aquifer.
The DRSE Report should be revised to demonstrate that monitoring well X ceased being a well
capable of monitoring seepage from EP1 when injection of clean water into nearby wells began
only four years after the 1990 installation of EP1.
The likely influence of injection of clean water on the data generated at monitoring well X was
a point of discussion during the recent NMED hearing on HMC DP-725. While NMED's
recently issued final Discharge Plan DP-725 retains monitoring well X as the sole monitoring
well down gradient of the four ponds, EP-1, EP-2, and the East and East Collection Ponds,
witnesses for all parties recognized that the ground water concentrations at monitoring well X
are "influenced" by injection and collection wells near it, as noted below.
The Hearing Officer's Report on the Record of the DP-725 Public Hearing, convened in
January 2010 at p. 8, summary of the testimony of HMC witness Al Cox included:
-------
"On further cross-examination, Mr. Cox agreed that Monitoring Well X, at the south end
of the small tailings pile near the injection wells, might be influenced by water from the
injection wells and therefore not purely reflective of seep from Pond 1. Well X is a
compliance well that will be looked at critically following remediation and cleanup. He
would not use it now as a monitoring point to identify seepage from Pond 1." (transcript
pp. 92-99)
"Considering the maintenance required at the RO plant, and a multitude of other factors,
a reasonable operating capacity is 540 gallons per minutes (GPM), 10% below the 600
gpm theoretical maximum." (transcript p. 99)
The Hearing Officer reported at pp. 8-9 that the testimony of HMC Witness Dr. Al Kuhn
included:
"[n]o leak detection system was installed at Pond 1, but there is an active collection
system of wells there that would collect water that might seep away from Pond 1. The
collection wells would likely not give an indication of leakage from Pond 1 because
downstream of those wells is a set of injection well and it would be difficult to see a
chemical signature that would be distinctly from Pond 1." (transcript, pp. 107 - 112)
"The collection wells and other wells downstream will be effective after the ground
water injection program is finished and can be used later to monitor residual seepage. If
Pond 1 were leaking today, the leakage would be collected by the collection wells."
(transcript, pp. 107 - 112)
The Hearing Officer reported at pp. 22-23 that HMC witness George Hoffman testimony
included:
"There are two wells DD and DD2, which will serve as monitoring wells to detect
leakage at Pond 3. There is no monitoring well to the west because the western
saturation of the alluvial aquifer is in that portion of the evaporation pond, Well X is
naturally down gradient of the Small Tailings Pile and Evaporation Pond 1 is still a very
appropriate monitoring point for the area. They [the injection wells] have reversed
gradient, but when the ground water restoration program ceases, gradient ground water
will turn and flow back to this area through Well X." (transcript pp. 368-370)
The Hearing Officer reported, at p. 30, that NMED witness Gerard Schoeppner:
"Agrees that Well X is influenced by the injection wells and that it is appropriate to have
a monitoring well at Pond 1 that would actually monitor potential leaks from that pond."
(transcript pp. 440-443)
8
-------
And that Mr. Schoeppner:
"Agrees that monitoring well X is influenced by the injection of clean water nearby, but
believes it is still useful in determining whether there are increased contaminant levels in
the alluvium, (transcript pp. 445-448)
The Hearing Offer reported at p. 31 that BVDA witness Paul Robinson:
"Understood that witnesses for the Applicant and the Bureau recognize that monitoring
well X is not effective at detecting leaks that may occur from Pond 1 because of its close
proximity to a row of injection wells. Based on that information, he recommends that the
state supplement the discharge plan with a condition requiring the installation of a new
monitoring well designed to serve as a leak detection monitoring point near Pond 1. The
K-line of wells mentioned by Mr. Schoeppner were not constructed for use as
monitoring wells but for other purposes." (transcript pp. 493, 497)
The DRSE Report should more accurately and effectively address the effectiveness of
monitoring well X. The DRSE Report should also be revised to evaluate the significance of the
influence of the injection wells and other aspects of the HMC injection and collection well
system on uranium concentrations detected in monitoring well X.
The DRSE Report should be revised to include an evaluation of the adequacy of monitoring
well X to demonstrate "plume capture" and detect contaminants leaking from the small tailing
pile, or EP1 on top of the pile, or the other ponds and tailings pile, because of the influence of
injection well water on the uranium concentration trend in monitoring well X.
The DRSE Report should be revised to address whether monitoring well X is located in a flow
path that could detect seepage from the East and West Collection Ponds, EP-2 and EP-1
independent of the injection of clean water. If no flow path from the ponds to monitoring well X
can be identified, the DRSE Report should be revised to identify a measure recommended by
the RSE contractors to establish a more effective monitoring well in the south side of EP1, the
other ponds south of the large tailings pile and the small tailings pile.
The DRSE Report should be revised to recommend additional monitoring well sites at locations
not compromised by clean water injection, as is the case with well X, or rising uranium trends,
as is the case with monitoring well DD, be identified to more effectively monitoring the current
and near-term (10 yrs+) potential leakage from the four ponds.
The DRSE Report should be revised to address the adequacy of the monitoring well and point
of compliance well pattern in place at the HMC site and identify alternative monitoring well
locations in recognition of the sources of dilution of uranium at well X and the rising uranium
concentration trend at well DD.
9
-------
C. Over Prediction of Flushing Performance
Observations
At p. 16, the DRSE Report states that the HMC ground water model "likely over predicts
performance of flushing."
Recommendations
The DRSE Report should be revised to more fully address the implications and consequences of
the over prediction of flushing performances and identify recommended actions to respond to
the HMC ground water model's over prediction of flushing performance.
The DRSE Report should be revised to identify the degree to which performance of flushing has
been over predicted.
The DRSE Report should be revised to identify mechanisms for more accurate prediction of
flushing performance and the consequences of more accurate assessed flushing performance
including, but not limited to, the likely ground water conditions and distribution of uranium and
other contaminants in the large tailings pile if flushing is more accurately predicted.
The DRSE Report should be revised to identify the parameters in the HMC ground water
model that lead to over prediction of flushing effectiveness and options for revising or
recalibrating applicable models the models to provide more accurate predictions.
D. Identifying Accurate Groundwater Conditions in the Middle Chinle Aquifer
Observations
At p. 16, the DRSE Report states that the ground water conditions in the Middle Chinle aquifer
at the site "don't make hydrologic sense."
Recommendations
The DRSE Report should be revised to include additional graphic information to identify the
extent of the Middle Chinle and other aquifers on site and indicate where the Middle Chinle
aquifer may be either used or affected by seepage from the tailings piles on the HMC site.
The DRSE Report should be revised to identify activities and investigations necessary to
overcome the lack of accuracy regarding the hydrology of the Middle Chinle aquifer.
The DRSE Report should be revised to identify the significance of understanding the hydrology
of the Middle Chinle aquifer to the HMC remediation system and the RSE Report.
10
-------
E. Life-cycle Cost and Effectiveness of Remediation Options Identified
Observations
At pp. 27-28, the DRSE Report discusses the high cost of tailings removal to a prepared site.
The DRSE Report includes a sustainability review of the tailings removal options but does not
include a sustainability review of other remedial options identified.
In an April 9, 2010 e-mail, the RSE Contractor team leader stated, "We are working on the
sustainability review of the other alternatives, including the continuation of the pump and treat
system for some period of time, and for a slurry wall with limited pump and treat." In that
email, the RSE contractor team leader did not indicate if or when that sustainability review will
be made available for review or if/when a revised DRSE Report incorporating that information
will be available for review.
Recommendations
The DRSE Report should be revised to provide lifecycle cost, emission or energy consumption
comparisons among long-term remediation options identified in order to provide for balanced
comparison of long-term costs for the range of alternatives identified in comparison to the cost,
long-term potential for successful completion of remediation, and consequences of continuation
of the HMC remediation system as proposed.
The DRSE Report should be revised to provide comparisons of the effectiveness of the physical
barriers - slurry walls and reactive permeable barriers - that it recommends with the tailings
removal options for long-term remediation of ground water at the site to meet performance
objectives established in the Uranium Mill Tailings Radiation Control Act. The Act requires
completion of closure and containment without active monitoring and maintenance as the
measure of tailings reclamation effectiveness.
The DRSE should be revised to eliminate the recommendation that, "Relocation of the tailings
should not be considered further given the risks to the community and workers and the
greenhouse gas emissions that would be generated during such work" unless and until a
balanced comparison of the full range of life-cycle costs and benefits, including considerations
of long-term remediation effectiveness of the range of remedial alternatives, is incorporated in
the Remediation System Evaluation.
The DRSE Report should be revised to identify and evaluate both 1) long-term monitoring and
maintenance costs and 2) likelihood of long-term effectiveness of the range of alternatives
identified, including continuation of the current remediation system and implementation of the
alternatives identified. Alternatives include elimination of the flushing system, slurry wall,
reactive permeable barriers, tailings removal and any other system with potential for long-term
remediation success. Consideration of long-term remediation effectiveness and monitoring and
maintenance costs should be incorporated into the RSE contractor team's sustainability review
so that remediation performance as well as energy consumption and worker safety issues can be
considered for all alternatives.
11
-------
As tailings removal remains the only conceptual option that allows for elimination of the source
of pollution from the HMC site, the DRSE Report should be revised to retain tailings removal
as the sole remediation alternative that provides for the potential to minimize or eliminate the
need for active long-term monitoring and maintenance after standards are attained.
F. Spray Evaporation as a Variable in Determination of Evaporation
Performance and Evaporation Options
Observations
Little attention has been paid in the DRSE Report or in other analyses of the direct relationship
between the scope of enhanced evaporation from the spray systems and size of the footprint of
remediation-related ponds at the HMC site. Spray evaporation rates have been considered as a
finite or fixed factor in the evaluation of evaporation at the HMC site rather than as a factor that
can be adjusted to meet remediation needs by varying spray evaporation capacity or modifying
evaporation technology.
To illustrate the effectiveness of spray system capacity on evaporation performance, two
documents and a descriptive memo were forwarded to the RSE contractors on March 18. These
documents, which are provided in Appendix B, provide a basis for identifying the full
evaporation potential of spray systems in use at the HMC site and for developing a quantitative
comparison of the characteristics of spray evaporation technologies. Appendix B includes a
relatively brief paper by Gregory Flach and colleagues that provides an overview of
"Evaporation Principles" and identifies and applies quantitative methods to evaluate the
evaporation system performance for a site in Georgia.
Flach and colleagues also published another report that provides a quantitative evaluation of a
"Turbomist evaporator", the same brand as one of the spray systems in place at the HMC site.
That report, "Field Performance of a Slimline Turbomist Evaporator under Southeastern U. S.
Climate Conditions" (available at http://sti.srs.gov/fulltext/rp2003429/rp2003429.pdf). is even
more directly relevant for the HMC site because it explicitly discusses field evaluation of
"Turbomist" evaporative sprayers from the same manufacturers as some of the spray systems in
use at the HMC site and provides much more detailed information on field performance
evaluation methods.
The HMC spray systems have not been subject to any quantitative evaluation of spray
evaporation effectiveness and spray fallback as was conducted by Flach and others in their two
reports. Neither have the current spray systems at the HMC site been the subject a quantitiative
evaluation of the distribution of particulates and radionuclides, including but not limited to,
radon and radon daughters in the liquids passing through the spray system.
DP-725 recently issued by NMED includes the following condition: "HMC shall operate the
forced spray system such that the spray remains within the confines the ponds to the extent
practicable. HMC shall submit plan to NMED for approval within 60 days of issuance of this
12
-------
Discharge Permit outlining automated operation of the forced sprayers in EP-1, -2 and -3. The
plan shall include, but is not limited to, wind conditions that sprayers will not be operated under
such as maximum wind speed and wind direction, how automated controls will be utilized to
shut-off sprayers, and how wind speed will be measured."
In the DP-725 Transcript at p. 19 -20 , Al Cox, a HMC witness stated,
"In 2008,1 believe, we commissioned ... an electronic shutdown system on our pump
systems for Evaporation Pond 1 in which it takes some ... wind speed and direction data
and information, and you can put in set points so that a sustained given mile per hour wind
speed ... and direction can actually shut those systems down. We still are at the present
time trying to optimize that. . . system to determine what are the best set points to trigger
an automatic shutdown from higher winds."
BVDA members report observing spray operations at the HMC ponds during recent spring days
when sustained winds exceeded 40 miles per hour. Those observations indicate that spray
operations may be continuing during high wind conditions.
Recommendations
The DRSE Report should be revised to identify a range of spray evaporation rate and
technology options in comparison to the spray evaporation technology in use at the HMC site.
The DRSE Report should be revised to identify a range of spray evaporation rate options among
the remediation system modifications it recommends and identify their implications for pond
configuration, acreage and evaporation performance.
The DRSE Report should be revised to identify the need for, and scope of, a quantitative
evaluation of spray evaporator performance and effectiveness including evaporative effect,
fallback or sprayed fluids, and distribution of particulates and radionuclides including radon and
radon daughters passing through the spray system.
The DRSE Report should be revised to identify the scope of data gathering and system
monitoring considerations, including spray shut-down systems during high winds, necessary for
effective performance of and effective evaluation of performance of the spray system in the
"forced spray plan" required by DP-725.
G. Remediation Cost Recovery
Observations
The DRSE Report does not identify the cost of HMC remediation to date or project a cost for
completion of remediation for any of the options considered except the tailings removal option.
The DRSE Report does not address the public cost of remediation at the HMC site; it does not
13
-------
acknowledge the cumulative cost to taxpayers of the federal government's payment of 51
percent of the remediation costs at the HMC site for the past three decades. Similarly, the DRSE
Report does not identify the projected cost of future decades of remediation, monitoring and
maintenance at the HMC site unless contamination is removed from the alluvial aquifer of the
San Mateo Creek.
The DRSE Report does not identify or consider the opportunity for the application of EPA's
"Federal Incentives for Achieving Clean and Renewable Energy Development on Contaminated
Lands" (http://www.epa.gov/reg3wcmd/ca/pdf/Federal%20Incentives_050108.pdf) to the HMC
site as a means to generate employment, energy and income to fund remediation at the site.
The potential to install large-scale renewable energy projects on the hundreds of acres in and
around the HMC site that EPA's Federal Incentives program could support is facilitated by the
flat slopes, existing electrical and transportation infrastructure, and large land areas on site that
surround the tailings piles.
Implementation of a renewable energy project at the HMC site while remediation continues
would provide employment and generate income to offset the long-term cost of remediation to
taxpayers for the past 30 years of remediation and future remedial activities.
Recommendations
The DRSE Report should be revised to identify the anticipated cost and timeline for completion
of remediation.
The DRSE Report should be revised to identify the opportunity to construct and operate a
renewable energy system at the HMC site as a means to generate income to offset long-term
remediation costs and to provide local employment.
H. Distribution and Review of a Revised DRSE Report for Comment Before
Completion of a Final RSE Report
Observations
The RSE contractor team leader informed the RSE stakeholder team that the contractor would
be recalculating evaporation rates and considering revisions to the DRSE Report in an e-mail
dated April 9, 2010, more than six weeks after initial distribution of the DRSE Report and only
two weeks before the April 23, 2010 informal comment period deadline. However, no revisions
to the RSE review and completion schedule associated with these revisions have been
identified.
It is not possible to accurately guess at which portions of the analysis, conclusions and
recommendations in the DRSE Report related to evaporation options and pond configurations
will or will not be influenced by the recalculation of evaporation rates.
14
-------
Neither EPA or the RSE contractor team has identified a timetable for distribution and review
of revisions to the DRSE Report to reflect long-term costs and benefits or other attributes of
remediation alternatives the RSE contractor anticipates will be generated from the second point
in the April 9, 2010 e-mail: "We are working on the sustainability review of the other
alternatives, including the continuation of the pump and treat system for some period of time,
and for a slurry wall with limited pump and treat."
Consideration of long-term costs and performance assessments for remediation alternatives is
critically important to the usefulness of the RSE process for future decision-makers. While the
DRSE Report includes the conclusion that remediation progress to date is not sufficient to attain
uranium concentration reductions to the 2 mg/1 range by 2012, and therefore attainment of
applicable standards by the projected date of 2017 is not likely to be possible, the DRSE Report
provides no projection of an alternative date for completion.
Recommendations
The DRSE Report should be revised to identify the estimated length of time that the
remediation options identified will be in place or operated and bases for estimation of the
longevity of those remedial options.
To provide for stakeholder review of a revised DRSE Report before it is finalized, it is strongly
recommended that EPA establish a timeline for distribution and RSE stakeholder review of a
revised DRSE Report which includes the conclusions and recommendations resulting from the
revised evaporation rate calculations and the "sustainability review" for remediation
alternatives.
15
-------
I. TASC Contact Information
E2 Inc. Project Manager and Work Assignment Manager
Terrie Boguski, P.E.
913-780-3328
tboguski@e2inc.com
Wm. Paul Robinson and Chris Shuey, TASC Subcontractors
Southwest Research and Information Center
P.O. Box 4524, Albuquerque, NM USA 87196
505-262-1862
sricpaul@earthlink.net
sric.chris@earthlink.net
E2 Inc. Program Manager
Michael Hancox
434-975-6700, ext 2
mhancox@e2inc. com
E2 Inc. Director of Finance and Contracts
Briana Branham
434-975-6700, ext 3
bbranham@e2inc. com
E2 Inc. TASC Quality Control Monitor
Paul Nadeau
603-624-0449
pnadeau@e2inc. com
-------
Appendix A
Overview, Conclusions and Recommendations
from
"Draft Focused Review of Specific Remediation Issues for the
Homestake Mining Company (Grants) Superfund Site,"
February 2010
"The current evaluation (DRSE, 2010) of the remediation efforts at the Homestake
Mining Company (Grants) Superfund site has been conducted on behalf of the US
Environmental Protection Agency (US EPA) by a technical team at the US Army Corps
of Engineers Environmental and Munitions Center of Expertise composed of Dave
Becker, Carol Dona and Brian Healy. The evaluation supplements a previous
Remediation System Evaluation (RSE) conducted for the site by Environmental Quality
Management (EQM, 2008)."
ISSUES
"Specific issues addressed in DRSE 2010 as identified in the Scope of Work include:
1) Evaluate the capture of contaminant plumes in the alluvial and Chinle aquifers;
2) Evaluate the overall strategy of flushing contaminants from the large tailings pile
with discharge of wastes to on-site evaporation ponds and to identify and compare
alternatives;
3) Assess potential modifications to the current ground water treatment plant to
improve capacity;
4) Evaluate the projected evaporation rates for the existing on-site ponds and for a
proposed evaporation pond west of the on-site tailings piles, as it may affect the
restoration activities at the site;
5) Assess the adequacy of the monitoring network at the site;
6) Evaluate the current practice of irrigating with untreated water; and
7) Evaluate the smaller of the two tailings piles at the site as a potential source of
contamination and the future need for a more conservative cap than the radon barrier.
"A stakeholder involvement process to exchange information has been since the initiation
of the project, the DRSE the reports that the RSE team has found very helpful in focusing
and facilitating the analysis.
"The DRSE analysis of current and past environmental conditions as well as the current
and past operations of the extraction, injection, and treatment systems has been conducted
by the ACE RSE Team following a single site visit in April, 2009."
-------
CONCLUSIONS
"Major conclusions in the RSE include:
A. Ground water quality restoration is very unlikely to be achieved by 2017;
B. Flushing of the large tailings pile is unlikely to be fully successful at removing most
of the original pore fluids or to remediate the source mass present in the pile due to
heterogeneity of the materials;
C. Long screened intervals in wells complicate the interpretation of water quality in
and below the large tailings pile;
D. The mill site may be an additional source of contaminants;
E. Control of the contaminant ground water plumes seems to depend on both hydraulic
capture and dilution;
F. There may have been widespread impacts on the general water quality (e.g., ions
such as sulfate) of the alluvial aquifer since mill operations began, but the limited
amount of historical data precludes certainty in this conclusion;
G. Upgradient water quality has declined over time, primarily in the western portion of
the San Mateo drainage and this may be affecting concentrations in northwestern
portions of the study area;
H. Ground water modeling has generally been done in accordance with standard
practice. The seepage modeling likely overestimates the efficiency of flushing of the
tailings;
I. The control of a uranium plume in the Middle Chinle aquifer may be incomplete;
J. There are no apparent impacts to the San Andres aquifer though data are limited;
K. There is no indirect evidence of leakage from the evaporation and collection ponds,
though the interpretation of water level and concentration data are complicated by the
significant injection and extraction conducted in the immediate vicinity of the ponds;
L. Current constraints to treatment plant operations include the evaporative capacity of
the ponds, clarifier operations, and possibly reverse osmosis capacity;
M. Evaporation rates for the ponds at the site are likely to be in the 65-80 gpm on an
annual basis when accounting for climatic conditions and salinity of the pond
contents;
N. The monitoring program at the site is extensive and not clearly tied to objectives.
There may be redundancies in the network in a number of locations in the alluvial
aquifer. Additional monitoring points are necessary in the Upper and Middle Chinle
aquifers to better define plume extent and migration. Monitoring frequency is
irregular but generally from semi- annual to annual. Air particulate monitoring
appears adequate to assess anticipated effluent releases from the site, however, there
is a need to confirm assumptions. The potential for release of radon from the
STP/evaporation pond area should be assessed;
O. Irrigation with contaminated water has resulted in accumulation of site
contaminants in the soil of the irrigated land. These accumulations are unlikely to
migrate to the water table over time, however;
P. Water used for irrigation could be successfully treated with ion-exchange
technology
18
-------
RECOMMENDATIONS
"Based on the DRSE analysis conducted, a number of recommendations were offered
including:
A. The flushing of the tailings pile should be curtailed;
B. Simplification of the extraction and injection system is necessary to better focus on
capture of the flux from under the piles and to significantly reduce dilution as a
component of the remedy;
C. Further evaluate capture of contaminants west of the northwestern corner of the
large tailings pile;
D. If not previously assessed, consider investigating the potential for contaminant
mass loading on the ground water in the vicinity of the former mill site;
E. Further investigate the extent of contaminants, particularly uranium, in the Upper
and Middle Chinle aquifers and resolve questions regarding dramatically different
water levels among wells in the Middle Chinle;
F. Consider geophysical techniques, such as electrical resistivity tomography to
assess leakage under the evaporation ponds;
G. Assure decommissioning of any potentially compromised wells screened in the San
Andres Formation is completed as soon as possible;
H. Consider construction of a slurry wall or Permeable Reactive Barrier (PRB) around
the site to control contaminant migration from the tailings piles. The decision for
implementing such an alternative would depend on the economics of the situation;
I. Relocation of the tailings should not be considered further given the risks to the
community and workers and the greenhouse gas emissions that would be generated
during such work;
J. If geotechnical considerations allow, consider expansion of the evaporation pond
on the small tailings pile as means to enhance evaporative capacity;
K. Consider either the pretreatment of high concentration wastes in the collection
ponds as is currently being pilot tested, or adding RO capacity to increase treatment
plant throughput and reduce discharge to the pond;
L. Develop a comprehensive, regular, and objectives-based monitoring program;
M. Quantitative long-term monitoring optimization techniques are highly
recommended;
N. Adjust Air Monitoring Program to perform sampling of radon decay products to
confirm equilibrium assumption, consider use of multiple radon background locations
to better represent the distribution of potential concentrations and assess the radon gas
potentially released from the evaporation ponds, especially during active spraying;
and
O. Though risks appear minimal with the current irrigation practice, consider treatment
of contaminated irrigation water via ion exchange prior to application as a means to
remove contaminant mass from the environment.
19
-------
Appendix B
TO: Dave Becker, RSE Team
FROM: Paul Robinson
DATE: March 18, 2010
SUBJECT: Evaporation Rate Materials
TURBOMISTER - a supplier of spray evaporation equipment used at Evaporation Pond
1 at the HMC site has a wide range of material on the theory and practice of spray
evaporation.
An overview of spray evaporation rate considerations, including droplet size, evaporator
through put and other factors is at:
http://www.turbomister.com/turbomist-evap-rates.php
An evaporation efficiency conversion chart relating pan evaporation achieved in inches
per month to volume of pond circulated through the evaporators is at:
http://www.turbomister.com/PDFs/Efficiency%20conversion%20Table%20Turbomist.pd
f - copy attached
A technical paper addressing evaporation theory and practice including consideration of
spray fallback factor in spray evaporation rate evaluation is at:
http://www3.interscience.wilev.eom/i ournal/112475413/abstract?CRETRY=l&SRETRY
K) - copy attached
Gregory P. Flach, Frank C. Sappington, and Kenneth L. Dixon, "Field Performance of a
Fan-Driven Spray Evaporator", REMEDIATION, Spring 2006
ABSTRACT
"An emerging evaporation technology uses a powerful axial fan and high-pressure spray
nozzles to propel a fine mist into the atmosphere at high air and water flow rates.
Commercial units have been deployed at several locations in North America and
worldwide since the mid-1990s, typically in arid or semiarid climates. A commercial
spray evaporator was field tested at the U.S. Department of Energy's Savannah River Site
in South Carolina to develop quantitative performance data under relatively humid
conditions. A semi-empirical correlation was developed from eight tests from March
through August 2003. For a spray rate of 250 L/min (66 gpm) and continuous year-round
operation at the Savannah River Site, the predicted average evaporation rate is 48 L/min
(13 gpm)." © 2006 Washington Savannah River Company*
-------
SLIMLINE WHWACJimiHG LTD.
CONVERSION TABLE FROM NET PAN EVAPORATION TO TURBOMIST
EFFICIENCY ESTIMATES FOR THE TURBOMIST S30P EVAPORATOR
This chart is indicated in inches per month. If you have annual pan evaporation in feet, convert to inches
And divide the total by 12 months to determine the average pan evaporation rate to use below.
Percentage
of volume
Pumped aloft
This conversion chart is the property of Slimline Manufacturing Ltd an is intended to
give our evaporator custom base a conservative estimate of what our S30P evaporator
models will do at their site, based upon the net pan evaporation provided.
-------
REMEDIATION Spring 2006
Field Performance of a
Fan-Driven Spray Evaporator
Grec[ory_P._Fl_ach
Fra n k^Sagjgiri gto n
Kenneth L. Dixon
An emerging evaporation technology uses a powerful axial fan and high-pressure spray nozzles
to propel a fine mist into the atmosphere at high air and water flow rates. Commercial units have
been deployed at several locations in North America and worldwide since the mid-1990s, typically
in arid or semiarid climates. A commercial spray evaporator was field tested at the U.S.
Department of Energy's Savannah River Site in South Carolina to develop quantitative perfor-
mance data under relatively humid conditions. A semiempirical correlation was developed from
eight tests from March through August 2003. For a spray rate of 250 L/min (66 gpm) and contin-
uous year-round operation at the Savannah River Site, the predicted average evaporation rate is
48 L/min (13 gpm). © 2006 Washington Savannah River Company*
INTRODUCTION
Evaporation provides one mechanism for reducing the volume of wastewater, a com-
mon component of an overall wastewater management strategy. Example applications
include mining, distillation and textile plants, animal waste disposal, phosphate fertil-
izer production, and landfill management. Evaporation also has application to
groundwater remediation. For example, the Savannah River Site (SRS) is using phy-
toremediation to reduce the discharge of tritiated groundwater to a stream (Blount
et al., 2002). The remediation project involves capturing a tritium (H-3) plume in a
man-made pond located at the seepline, and spray-irrigating the collected water over
an upgradient mixed pine and deciduous forest. Enhanced evapotranspiration can sig-
nificantly reduce the net flux of tritium discharging to surface water (Blount et al.,
2002). However, evapotranspiration demand is minimal during winter months, and
heavy precipitation in any season significantly increases influx to the collection pond
due to surface runoff. Under these circumstances, the net influx can exceed the
holding capacity of the pond, causing overflow. Thus, a supplemental technology,
such as spray evaporation, was desired to remove excess water from the collection
pond during winter and wet periods.
An emerging evaporation technology uses a powerful axial fan and high-pressure
spray nozzles to propel a fine mist into the atmosphere at high air and water flow rates.
Commercial examples include the Slimline Manufacturing Ltd.Turbo-mist (http://
www.turbomist.com/) and SMI® Super Polecat evaporators (http://www.evapor.com/).
Such evaporators rely on the sensible heat that can be extracted from unsaturated (< 100
percent humidity) air to drive evaporation. Incoming "dry" air is brought into contact with
the spray field through a combination of the mechanical fan and natural wind, and simulta-
© 2006 Washington Savannah River Company. This article is a U.S. government work and, as such, is in the public domain in the United States of America. 97
Published online in Wiley Interscience (www.interscience.wiley.com). DOI: 10.1002/rem.20083
-------
Field Performance of a Fan-Driven Spray Evaporator
When unsaturated air is
brought into contact with
liquid water, with no heat
transfer to or from the
overall system, liquid evap-
orates and air is cooled
until thermodynamic equi-
librium is reached.
neously cooled and humidified through evaporation. Because the energy for evaporation
comes from a natural source, the overall cost is relatively low.
Field performance of these evaporators is affected by a number of factors, including
the flow rate, temperature, and humidity of the air contacting the spray field, and the
spatial distribution, suspension time, and size of spray droplets. Hot, dry, and windy
conditions are most favorable to spray evaporation, and units have been commercially
deployed at several locations in North America and worldwide since the mid-1990s, typ-
ically in arid or semiarid climates. Although anecdotal information and limited field
J o
measurements (Ferguson, 1999) suggest the technology is effective, at least in arid cli-
mates, quantitative performance data under more humid conditions are not available.
Such data were needed to evaluate the technology for application at the SRS tritium
phytoremediation site.
The purpose of this technical note is to provide evaporator performance data for
Southeast U.S. climate conditions, and to present a semiempirical correlation for pre-
dicting evaporation near the range of conditions tested. The field data were acquired at
the U.S. Department of Energy's Savannah River Site near Aiken, South Carolina, from
late March through mid-August 2003. The specific system tested is the Slimline Turbo-
mist evaporator.
EVAPORATION PRINCIPLES
When unsaturated air is brought into contact with liquid water, with no heat transfer to
or from the overall system, liquid evaporates and air is cooled until thermodynamic
equilibrium is reached (100 percent humidity). Such a process is termed adiabatic satu-
ration and is the principle behind swamp coolers used for residential cooling in the
Southwest United States and agricultural cooling (e.g., poultry houses).The energy re-
quired to vaporize liquid water (latent heat of vaporization) is extracted from unsatu-
rated air through cooling (sensible heat). The amount of cooling as a function of the
temperature and relative humidity of the incoming air stream can be determined
through application of the first law of thermodynamics, which states that enthalpy is
conserved in a open system. With minor approximation, the adiabatic saturation process
can be described by:
AX
out
(1)
where h* — enthalpy of moist air per unit mass of dry air, h — enthalpy of dry air, y —
specific humidity or humidity ratio, and hw = enthalpy of water vapor (Reynolds and
Perkins, 1977). The thermodynamic properties of moist air can be readily computed
from an American Society of Heating, Refrigerating, and Air-Conditioning Engineers
J o' o o' o o
(ASHRAE) handbook (e.g., ASHRAE, 1985) or equivalent source.
As an example calculation, the annual average temperature and relative humidity at
the Savannah River Site are 18°C (65°F) and 68 percent, respectively (Hunter &Tatum,
1997). For these conditions, the evaporative cooling achieved when the incoming air
stream is saturated is 3.7°C (6.6°F). Exhibit 1 shows contours of constant evaporative
cooling degrees resulting from various combinations of temperature and relative humid-
ity. The dashed box defines an approximate envelope of likely weather conditions at the
Savannah River Site.
92
© 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem
-------
REMEDIATION Spring 2006
Evaporative cooling, \'i: - 10 8
• Annual
20 40 60 80
Relative hu mid ity(%)
Exhibit 1. Evaporative cooling potential as a function of
temperature and relative humidity
Spray evaporation under atmospheric conditions is expected to be proportional to
the cooling and evaporation amounts computed under adiabatic saturation conditions.
For evaporation to be sustained, air (and water) must be continuously supplied to re-
plenish the system. An energy balance expanding on Eq. (1) indicates that evaporation
of liquid water into unsaturated air is proportional to the mass flow rate of air deliv-
ered to the system. For atmospheric spray evaporation, fresh air is delivered to the
spray field through natural winds. Thus, the spray evaporation rate is also expected to
be proportional to local wind speed. The overall dimensions of the spray field, and the
distribution, suspension time, and size of spray droplets within, are also expected to af-
fect the evaporation rate.
EXPERIMENT DESIGN AND SETUP
In many evaporator applications, water is drawn from a holding pond (e.g., mine tail-
ings) and sprayed into the air. Droplets not evaporated fall back into the pond. At the
Savannah River Site, deployment over dry land was under consideration, leading into
field testing. For this situation, high evaporation with little or no fallback was considered
to be optimal. Therefore, field testing focused on reduced spray rates (20 to 150 L/min)
and smaller droplet sizes compared to that produced by the vendor's default spray noz-
zle configuration (~250 L/min). Ultimately, the evaporator was deployed at the phy-
toremediation collection pond, for which fallback was not a concern.
To measure evaporator performance for a particular nozzle configuration and
weather condition, specialized collection devices were deployed on a grid to measure
spray fallback. The evaporation rate was then computed as the spray rate minus the fall-
back rate. The surveyed grid system is depicted in Exhibit 2, along with an example fall-
back pattern. A 6.1 -m (20-ft) square spacing was chosen near the origin of the grid
where the spray evaporator was located. Collection devices were deployed at a variety of
grid locations to handle particular weather conditions—primarily, wind speed and di-
rection. To handle a wide range of potential fallback amounts over the duration of a field
© 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem
93
-------
Field Performance of a Fan-Driven Spray Evaporator
fallback rate (mm/d)
0,5 5 50
40
20
-20
o o c
-40 -20 ' 6 20 40
meters
Exhibit 2. Grid system defining placement of spray fallback
collection devices, and an example fallback pattern
test, both rain gauges and absorbent pads were used. For each absorbent pad, fallback
was determined from the area, and dry (pre-test) and wet (post-test) weights of the pad.
FIELD TESTING AND DATA
Eight field tests were conducted between March and August 2003 (Flach et al., 2003).
Comparison of the fallback measurements from the absorbent pads and rain gauges from
all tests indicated that the pads are capable of reliably retaining fallback amounts up to
approximately 5 mm (0.2 in) of water, while at least 5 mm (0.2 in) is needed with a rain
gauge to avoid readings that are biased low. Thus, if a rain gauge reading exceeded 5 mm
o o o o o o
at an individual grid location, that value was adopted as the fallback amount. Otherwise,
the absorbent pad measurement was selected. For each test, a map of spray fallback was
created by interpolating the point data from the preferred collection device at each grid
location onto a regular 6.1m (20 ft) X 6.1 m (20 ft) grid using a kriging interpolation
algorithm (Isaaks & Srivastava, 1989). Numerical integration of the kriged surface pro-
duced the total amount of spray fallback for a given test.
Exhibit 3 summarizes the evaporator configuration, average weather conditions, and
spray fallback for each field test. Because testing was conducted from March through
August, periods of rainfall were avoided, and daytime testing was preferred for logistical
reasons, most tests were conducted at relatively warm temperatures and moderate hu-
midity. An exception was the 16-hour overnight test beginning at 4:21 P.M. on March
31 and ending at 8:58 A.M. on April 1, for which the average conditions were 3.5°C
(38.3°F), 72% relative humidity, and 0.85 m/s (1.9 mph) wind speed.These conditions
were unfavorable for evaporation, and the evaporation rate was low.
DATA CORRELATION
Because the collection of test data summarized in Exhibit 3 only defines evaporator
performance under certain specific conditions, a model capable of predicting evapora-
94
© 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem
-------
REMEDIATION Spring 2006
Nozzle configuration
Test date
03/31/03
04/29/03
05/01/03
05/14/03
06/25/03
06/26/03
07/24/03
08/11/03
No.
30
30
30
30
30
27
27
30
Cores
25
25
25
25
25
45
45
45
Orifices
D2
D2
D5
D5
D5
D6
D6
D8
Spray
rate
(L/min)
23
23
59
63
61
96
99
148
Evap.
Weather conditions
rate Temp.
(L/min)
6.9
20
25
22
31
50
43
53
(°C)
4
25
26
22
31
31
29
29
Rel.
hum.
(%)
69
52
56
46
41
46
56
64
Wind
speed
(m/s)
1.3
2.1
3.1
0.9
1.6
2.2
2.0
2.9
Exhibit 3. Summary of evaporator field testing results
tion rates under more arbitrary conditions is desirable. Following the previously stated
expectation that the evaporation rate is largely proportional to the evaporative cooling
potential based on adiabatic saturation and wind speed, the dimensional evaporation
data are first normalized as
E' =
fl-AF-1/
(2)
where £' — normalized evaporation rate, £ — evaporation rate, a — empirical constant,
Ar = evaporative cooling, and V = wind speed.
Similarly, the spray rate is normalized as
Q
Q' =
o-AF-1/
(3)
where Q — normalized spray rate, Q^— spray rate, a — empirical constant, AT — evap-
orative cooling, and V = wind speed.
The evaporation rate is zero when the spray rate is zero. The field data suggest
the evaporation rate increases in proportion to spray rate initially but levels off at
higher spray rates. A nondimensional empirical function capturing this qualitative be-
havior is
1
E' =
(4)
where £' — normalized evaporation rate, b — empirical constant, and Q — normalized
spray rate. The limiting behavior of Eq. (4) is £' —> 0 as Q —> 0, and £' —» 1 as Q —> °°.
In terms of dimensional parameters, Eq. (4) is equivalent to the semiempirical model:
© 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem
95
-------
Field Performance of a Fan-Driven Spray Evaporator
3.0
2.5 -
3.
sr 2,0
I
i 15
o
a
5 1.0
V
0.5
o
0.0
o Field data
— - Infinite spray rate asymptote
Model extrapolation
Predictive model
0.0 0.5 1.0 1.5 2.0 2.5
Normalized spray rate, Q/(aAT V)
3.0
Exhibit 4. Normalized evaporation and spray rates
f =
a-AT"-1/
b
—
Q
(5)
with limits of £ -» 0 as Q-» 0, and £ -» a • Ar • V as Q-» oo. Optimal values for the
empirical constants a and b were determined using least-squares parameter fitting, with
the result of a = 1.24 X 10^m2/°C (0.49 gpm/°F - mph) and b = 1.45(unitless).
Normalized evaporation rate is plotted against normalized spray rate in Exhibit 4. The
model is observed to fit the field data reasonably well.
While the functional form given by Eq. (5) incorporates two factors influencing
evaporation, other important parameters (droplet size, residence time, etc.) are not ex-
plicitly considered. The latter influences are implicitly embedded in the empirical con-
stants a and b. Furthermore, limited field data were available to define optimal values and
test the robustness of the selected correlation. Thus, the predictive model is applicable to
the particular commercial system and environmental conditions tested. Extrapolation to
other evaporator models and weather conditions should be done with caution.
The nondimensional predictive model defined by Eq. (4) can be translated into the
equivalent dimensional form given by Eq. (5) for specific weather conditions (i.e., val-
ues of Ar and F). For the default spray rate of 250 L/min (66 gpm) and continuous
year-round operation at the Savannah River Site ( Ar = 3.7°C, V = 2.4 m/s,), the
predicted average evaporation rate is 48 L/min (13 gpm).
96
© 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem
-------
REMEDIATION Spring 2006
COST ANALYSIS
During field experimentation at the Savannah River Site, all power required to operate
the evaporator (axial fan and water pump) was supplied through a single portable diesel
generator. Power usage varied little during and between tests, and averaged 30 kW.
Electricity costs commercial users in the Southeast United States approximately $0.09
per kW-hr. For the projected annual average evaporation rate of 13 gpm, the projected
treatment cost is $3.50 per 1,000 gallons of water evaporated.
ACKNOWLEDGMENTS
The work described in this technical note was performed at the Savannah River
National Laboratory by Westinghouse Savannah River Company LLC for the U.S.
Department of Energy under Contract No. DE-AC09-96SR18500. The authors are
grateful to these institutions for permission to publish their findings and for the sup-
port of Phil Prater, DOE Project Team Lead. We also thank colleagues Susan Bell,
John Bennett, Gerald Blount, and Mo Kasraii for critical program support and tech-
nical assistance.
NOMENCLATURE
a, b = empirical constants
h* = enthalpy of moist air per unit mass of dry air
h = enthalpy of dry air
h = enthalpy of water vapor
£ = evaporation rate
£' = normalized evaporation rate
Q^= spray rate
Q^ = normalized spray rate
V = wind speed
Ar = evaporative cooling potential based on temperature and relative humidity
7 = specific humidity or humidity ratio
REFERENCES
American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). (1985). ASHRAE
handbook: 1985 fundamentals. Atlanta, GA: Author.
Blount, G. C., Caldwell, C. C., Cardoso-Neto, J. E., Conner, K. R., Jannik, G. T., Murphy Jr., C. E., et al.
(2002). The use of natural systems to remediate groundwater: Department of Energy experience at the
Savannah River Site. Remediation, 12(3), 43-61.
Ferguson, R. B. (1999). Management of tailings pond water at the Kettle River Operation. CIM Bulletin,
92(1029), 67-69.
Flach, G. P., Sappington, F. G., & Dixon, K. L. (2003). Field performance of a Slimline Turbomist evaporator
under Southeastern U. S. climate conditions (U). WSRC-RP-2003-00429. Aiken, SC: Westinghouse
Savannah River Company. Retrieved October 7, 2005, from http://sti.srs.gov/fulltext/rp2003429/
rp2003429.pdf
© 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem 97
-------
Field Performance of a Fan-Driven Spray Evaporator
Hunter, C. H., & Tatum, C. P., (1997). Meteorological annual report for 1996 (U). WSRC-TR-97-0214. Aiken,
SC: Westinghouse Savannah River Company. Retrieved October 7, 2005, from http://www.osti.gov/
dublincore/ecd/servlets/purl/574238-oiySQz/webviewable/574238.pdf
Isaaks, E. H., & Srivastava, R. M. (1989). An introduction to applied geostatistics. Oxford, UK: Oxford
University Press.
Reynolds, W. C., & Perkins, H. C. (1977). Engineering thermodynamics. New York: McGraw-Hill.
Gregory P. Flach, PhD, P.E., is a fellow engineer at the Savannah River National Laboratory (SRNL),
where he has worked the past 17 years on a variety of environmental and nuclear engineering topics. He
currently specializes in mathematical analysis and numerical simulation of porous media transport.
Frank C. Sappington, retired principal engineer at the Savannah River National Laboratory, has 22
years of civil engineering experience. At SRNL, he developed, deployed, and tested new groundwater remedi-
ation technologies, horizontal and vertical barrier systems, and groundwater extraction systems. His BS de-
gree in civil engineering is from the Southern Polytechnic State University.
Kenneth L. Dixon, P.E., is a principal engineer at the Savannah River National Laboratory, where he has
worked the past 14 years on a variety of environmental engineering projects. He specializes in pilot-scale
testing of innovative remedial technologies and numerical simulation of contaminant transport in the va-
dose zone.
9g © 2006 Washington Savannah River Company Remediation DOI: 10.1002.rem
-------
sc *,
** ,ifcsc *> Technical Assistance Services for Communities
* Contract No.: EP-W-07-059
TASC WA No.: R6-TASC-002
Technical Directive No.: R6-Homestake Mining-02
Comments on Air Monitoring and Radon Issues Raised in the
U.S. Army Corps of Engineers' Draft Remediation System Evaluation (Supplement)
for the Homestake Mining Company (Grants) Superfund Site, New Mexico
May 6, 2010
1.0 Introduction
This document provides the Bluewater Valley Downstream Alliance (BVDA) with comments on
air monitoring and radon issues raised in the U.S. Army Corps of Engineers' "Draft Remediation
System Evaluation (Supplement) for the Homestake Mining Company (Grants) Superfund Site,
New Mexico," a February 2010 draft document prepared by the U.S. Army Corps of Engineers'
(USAGE) Environmental and Munitions Center of Expertise for the U.S. Environmental
Protection Agency (EPA), Region 6.
The USAGE Draft Remediation System Evaluation (Supplement), hereinafter referred to as the
"DRSE Report," provides a concise review of the air monitoring system at the Homestake
Mining Company (HMC) site, with an appropriate focus on radon emissions. The DRSE Report
identifies several shortcomings in the monitoring system that could affect whether HMC can
demonstrate compliance with the U.S. Nuclear Regulatory Commission (NRC)'s 100-millirem-
per year (mrem/y) public dose limit. The DRSE Report's findings track closely with those of the
TASC Report No. R6-Homestake Mining-01 ("TASC Report," November 18, 2009), which
showed how doses could exceed the limit if a lower radon background value and higher radon-
radon progeny equilibrium factor were used in calculations of the Total Effective Dose
Equivalent (TEDE) (TASC, 2009; pp. 15-18, Appendix B). The RSE Team recommends
changes in the monitoring system to better define background radon, measure radon progeny to
develop a site-specific equilibrium factor, improve radon detection around tailings piles and
effluent ponds, and better understand site and local meteorology. NRC and EPA should review
the findings of both recent reports and consider developing a regulatory strategy to implement
the recommended changes in the HMC air monitoring program.
What the DRSE Report lacks with respect to air monitoring issues is a sense of urgency to
address the potential public health impacts of persistently high levels of radon measured at
monitoring stations located closest to homes in the communities located south and southwest of
the HMC site. The TASC Report (pp. 15-16) noted that some of the highest ambient levels of
radon recorded anywhere around Homestake's property in 2008 were at the two nearest-
residence monitor stations, HMC #4 and HMC #5. An analysis of 10 years of perimeter radon
monitoring, presented later in these comments, shows that these two stations have had the
highest average annual radon concentrations of any of Homestake's eight monitoring stations,
and that the levels are significantly higher than those recorded at the HMC site's background
monitor location, HMC #16. Like the DRSE Report, the TASC Report questioned the
appropriateness of HMC #16 serving as the sole background monitor station.
-------
No outdoor or indoor radon monitoring has been conducted outside of HMC's property boundary
since 1987-1988, when the Homestake Subdivision Radon Study detected average annual
"corrected" radon levels that were four to nine times greater than background (EPA 1989). In
recent sworn testimony, Bluewater Valley Downstream Alliance (BVDA) members raised
concerns about the potential health impacts of high radon levels and requested that a formal
health study be conducted in the community (NMED Secretary, 2010; testimony of Arthur
Gebeau, pp. 268-270, and testimony of Candace Head-Dylla, 281-282). The comments that
follow supplement and expand on the issues addressed in both the TASC Report and the DRSE
Report to provide all stakeholders, including BVDA members, with a more complete knowledge
of historic and recent ambient radon levels, an increased understanding of the range of sources of
radon, and an appreciation of the potentially significant health risks associated with chronic
exposure to radon at the levels observed in the community.
2.0 Review of Historic and Recent Radon Levels
2.1 Documentation. Six major studies of air monitoring for ambient radon in the region
surrounding the HMC site and in the residential areas near the plant were identified and reviewed
for these comments. The studies span 39 years, from 1972 to 2009, and are annotated briefly in
Table 1. Each of the studies used common radon detection equipment and sampling techniques,
and conducted calibration tests against sources having known concentrations of radon. While all
sampling techniques have some level of measurement and analytical error, and monitoring
devices and methods have improved over time, there is no reason to believe that the results of
these studies are not comparable for the purpose of gaining a broad understanding of trends in
radon levels in the Grants Mineral Belt generally and in the area of the HMC site over the past
four decades.
2.2 Data Extraction and Summaries. Ambient radon levels reported in these studies and data
sets were extracted and are summarized in Table 2. The NMEI study (1974) of radon in the
Village of San Mateo was conducted to determine baseline environmental levels prior to the
opening of the Mt. Taylor Uranium Mine. No non-background, or mining-influenced, sites were
selected for assessment. The 1975 EPA study (Eadie et al., 1976) and 1978-1980 NMEID study
(Buhl et al., 1985) included measurements at both background and non-background monitoring
sites. The background sites were located in both nearby communities (e.g., Bluewater Lake and
the Village of San Mateo) and communities farther away (e.g., the Town of Crownpoint) where
no uranium mining or milling had occurred previously. Non-background monitors were set up in
active uranium mining and milling areas in Ambrosia Lake, Milan and Bluewater village.
The 1983-1984 NMEID radiological assessment (Millard and Baggett, 1984) and the 1987-1988
Homestake Subdivisions Radon Study (HMC 1989; EPA 1989) were conducted to assess radon
levels in Broadview Acres, Murray Acres and Pleasant Valley Estates, the residential areas that
bordered the HMC site on the south and southwest at that time. The NMEID study designated
two of seven monitor locations as "background" (both were located 10 to 20 miles outside of the
area surrounding HMC and in opposite directions), while none of the monitoring locations in the
Homestake Subdivisions study was designated "background" or "non-background."
Accordingly, the overall mean "corrected" radon concentration of 1.9 picoCuries per liter-air
(pCi/1) was not designed background or non-background in Table 2. As discussed in Section
2.3, radon levels reported in the two subdivision studies are grouped with concentrations at
designated background monitoring sites for analysis of time trends.
-------
The last large data set, also summarized in Table 2, contains the results of 10 years of fenceline
monitoring conducted by HMC and reported semi-annually to NRC and the New Mexico
Environment Department (NMED). The data were extracted from the company's semi-annual
environmental monitoring reports (SAEMRs) and compiled in an Excel spreadsheet. They are
tabulated in Table 3a, and discussed in more detail in Section 2.5. Locations of seven fenceline
monitors and one background monitor, HMC #16, are shown in Figure 1, a map prepared by
HMC and presented as an exhibit in the January 12-13, 2010 public hearing on DP-725 (Baker
2010b). (See, also, DRSE Report, Figure 211, p. 39.)
Results for monitor station HMC #16 are included in the background column of Table 2 because
this station, which is located about 2.75 miles northwest of the Large Tailings Pile (LTP), is
designated as the background monitoring site for the facility. Results for HMC #4 and HMC #5,
designated as "nearest-residence" monitoring sites, are shown in the "non-background" column
of Table 2 to differentiate them from HMC #16, the designated background monitor. Radon
levels for monitors HMC #1, HMC #2, HMC #3, HMC #6 and HMC #7 were pooled into one
average concentration and placed in the "non-background" column because these stations are
sited at locations predicted to have the highest concentrations of airborne particulates (DRSE
Report Supplement, p. 37).
Results of air monitoring conducted by HMC at its perimeter monitor stations in the 1980s and
1990s were not reviewed or reported here because they are not available from the NRC's
ADAMS electronic document retrieval system. SAEMRs and other reports containing radon
levels for that period are likely housed in NRC's document repository in paper copies only. To
close the 20-year gap in radon monitoring data, HMC should compile, summarize and report all
fenceline radiological monitoring data from the 1980s and 1990s.
2.3 Analyses of the Historic Radon Data. Descriptive statistics for the historic radon data
were derived from the six studies listed in Table 1 or were generated anew using statistical
applications contained in Microsoft Excel. Means of average annual radon levels at background
monitoring stations and radon levels recorded at monitors in or next to the residential areas were
used to construct a plot of radon levels over time. This plot is shown in Figure 2. Standard
deviations reported by the studies' authors or calculated using Excel spreadsheet software are
depicted as error bars around mean values.
The plot in Figure 2 appears to depict two groups of data: (i) concentrations at background sites
ranging from 0.19 pCi/1 to 0.71 pCi/1 during the period 1972 to 1983; and (ii) average annual
radon levels in the two residential studies (1983-84 and 1987-88), at HMC's background monitor
(HMC #16) and at the nearest-residence monitor (HMC #4) between 1999 and 2009. The levels
in the more recent group were significantly higher than those in the earlier group. A trendline
applied to the data suggests an increasing trend in radon levels over time.2
1 DRSE Figure 21 is a copy of a map that HMC has used many reports for at least the last decade, but which is now
known to be incorrect with respect to the location of HMC #16. The more recent figure that is reproduced as Figure
1 in this report not only is stated to be accurate with respect to the location of HMC #16 (see, testimony of Kenneth
L. Baker, January 12, 2010 (HMC, 2010; Exhibit 36B)), but is also more legible.
2 Not depicted on Figure 2 is an average Rn-222 concentration of 2.1 pCi/1 was detected at Monitor #803 in the
November 1975 EPA radon study. According to the EPA report of the study (Eadie et al., 1976, pp. 8-10), this
monitor was located 1.0 miles south-southwest of the tailings pile in or next to Broadview Acres. The report
categorized Monitor #803 as a non-background monitoring site, and included in one of the data tables the following
-------
Several factors may explain the apparent differences in radon levels between the two periods. At
the time of the earliest studies, more than 60 uranium mines and three uranium mills were
operating in the region bounded by Interstate 40 on the south, the Mt. Taylor volcanic fields and
highlands on the east, and uplifted sedimentary sequences on the west and north (NMMMD,
2009). The investigators carefully selected sites for determination of background, ranging from
the Village of San Mateo on the northwest flank of Mt. Taylor to the Town of Thoreau 20 miles
west of the area, and the Town of Crownpoint, 35 miles northwest of the Ambrosia Lake mining
district. Even then, Buhl and colleagues (1985) reported that some of the monitoring locations
designated as background may have been influenced by mining and milling releases. The
authors stated that this finding explains why the average annual background concentrations of
0.57 pCi/1 (1979) and 0.50 pCi/1 (1980) were two to three times higher than background levels at
other locations not experiencing uranium mining. The high levels recorded in the residential
areas in the 1980s and the high levels reported at the nearest residence monitor (HMC #4)
indicate a source or sources of radon not found in the other communities.
The data in Table 2 and Figure 2 clearly show that outdoor radon levels approaching or
exceeding 2 pCi/1 have been detected in the residential areas next to the HMC site since at least
the early 1980s. An overall increase above background of between 1.2 pCi/1 and 1.7 pCi/1 Rn-
222 has been observed in or near the residential area over this time. At times, the radon levels in
the neighborhoods next to the HMC site have been more than 10 times higher than the lowest
background concentrations. The outdoor levels near the residences on average are five to six
times higher than the average U.S. level (0.4 pCi/1) reported by EPA (2010). The persistence of
average annual radon levels of 1.8 pCi/1 and 1.63 pCi/1 at the two nearest-residence monitors
over the last 10 years indicates that the problem is not going away.
2.4 Homestake Subdivisions Radon Study and EPA 1989 No-Action Record of Decision.
The Homestake Subdivisions Radon Study merits further discussion for two reasons. First, the
study documented high outdoor and indoor radon levels in the residential area through an
extensive sampling program. Second, the study resulted in a finding by EPA Region 6 that the
high ambient and indoor levels could not be correlated with emissions from HMC's operations.
As a result, EPA implemented a "No-Action Alternative" that did not require HMC to take any
remedial actions to lessen radon levels in the communities (EPA 1989). The Agency's Record of
Decision (ROD) recommended that residents living in eight homes having indoor radon levels at
or exceeding the EPA "action level" of 4.0 pCi/1 take one, two or three actions to reduce indoor
radon levels: (i) increase ventilation of crawl space, (ii) install high-efficiency, forced-air
heating, and (iii) seal cracks and openings in floors (EPA 1989, Table 8). The extent to which
these recommended repairs were made by the particular eight homeowners is not known.
As shown in Table 2, the average outdoor radon level of the 28 monitors in the community was
1.9 ± 0.4 pCi/1, bounded by extremes of 1.2 pCi/1 to 2.7 pCi/1. These were "corrected" values
that were reduced from "measured" radon levels by subtracting a calibration factor derived from
exposing the Track-Etch detectors to a known quantity of radon. The outdoor calibration factors
remark: "Elevated radon due to milling?" (Eadie et al., 1976, Table 3). The radon level for this monitor is not
placed in Figure 2 because the monitoring location was not categorized as a background site, but deemed a site
possibly influenced by releases from the HMC uranium mill. If this average radon level were to be included in
Figure 2, it would appear as a outlier nearly three times greater than the average radon level of the five background
monitors sampled in the EPA/Eadie study.
-------
ranged from 0.47 pCi/1 in the second quarter of the study to 0.95 pCi/1-air in the fifth quarter
(EPA 1989, p.7). The average measured outdoor radon concentration was 5.2 ± 1.53 pCi/1 on a
range of 2.8 pCi/1 to 8.2 pCi/1. As discussed in Section 4 below, these levels, when coupled with
an average corrected indoor radon concentration of 2.7 pCi/1, present lifetime lung cancer risks
on the order of 7 in 1,000.
2.5 Trends in Radon Levels at HMC Monitoring Stations. The RSE Team noted (DRSE
Report, p. 37) that HMC #6, the perimeter monitor station that is located one mile west of the
LTP and is designated as the background site for radioactive particulates, had a radon
concentration of 2.8 pCi/1 in the second half of 2008 — the single highest radon level recorded at
any of the monitors since 1999. However, a close examination of 10 years of radon levels at all
eight monitors (Table 3a) shows that HMC #6 had the fourth lowest annual average radon
concentration. As noted above, the two nearest-residence monitors, HMC #4 and HMC #5, had
the highest average annual radon levels over the 10-year sampling period, as shown in Figure 3.
The designated background monitor, HMC #16, did not have the lowest annual radon level;
HMC #3, which is located 0.8 miles east of the LTP, had the lowest annual radon level. The
nearest-residence monitors had the highest annual average radon levels, and all eight monitors
had average radon levels greater than 0.71 pCi/1, which was the highest average concentration of
the background levels recorded between 1972 and 1983 (Table 2 and Figure 2).
The results of a statistical analysis to test whether radon levels recorded at the two nearest-
residence monitors, HMC #4 and HMC #5, are significantly higher than levels recorded at the
background station, HMC #16, are shown in Table 3b. A t-Test for two samples (assuming
unequal variance) was performed on the data set using the Excel Data Analysis function and
assuming a normal distribution of the data.3 Only two monitors, HMC #3, located 0.8 miles east
of the LTP, and HMC #7, located within 1,000 feet of the Small Tailings Pile (STP), had radon
levels that were no different than those levels recorded at HMC #16. Radon levels at the rest of
the monitors were all significantly different than those levels measured at HMC #16. HMC #4
and HMC #5, the two nearest-residence monitors, had average annual radon levels significantly
higher than those at HMC #16, with/? values of 0.0000001 and 0.0002, respectively. This means
that the probability that the average levels in the nearest-residence monitors were different than
the average level in HMC #16 by chance only is infinitesimally small.
These analyses suggest that HMC #16 may be sampling a different population of ambient radon
gas than all but two of the other perimeter monitors, and perhaps all of them. While the
populations may be different, radon concentrations at all of the monitors around the HMC site
and at the background site are still far greater than the background levels recorded elsewhere.
These analyses validate the TASC Report's concern that HMC #16 may not represent true
background radon levels (it is located within 3 miles of abandoned mines located next to
Haystack Road), and add support to the RSE Team's recommendation for fresh characterization
of background by adding two or three new monitoring stations (DRSE Report, pp. iv, 37, 47).
2.6 Sources of Radon and Other Radioactive Materials. The HMC mill, which opened in
1958 and closed in 1990, was still operating at the time the Subdivision Radon Study was
3 This assumption was based on an examination of the differences between mean and median Rn concentrations
shown in Table 3b. The largest difference was -0.08 pCi/1 in HMC #5, and four of the eight monitors had mean-
median differences ranging from -0.02 to 0.01 pCi/1. These small differences mediated against using non-parametric
methods for the analysis.
-------
conducted in 1987-88. The mill was decommissioned and demolished between 1993 and 1995,
and interim soil covers were placed on the sides of the LTP and STP during that time (DRSE
Report Supplement, pp. 3, 38). The top of the LTP has a thin dirt cover, but has not been fully
covered in order to accommodate operation of the wells used in the ground-water remediation
flushing program.
2.6.1 HMC Waste Management Units. In addition to the LTP and STP, other sources of
radioactive emissions from the site include the reverse osmosis effluent treatment plant located at
the southwest corner of the LTP and the four existing collection and evaporation ponds located
on the south side of the LTP. Evaporation Pond #1 (EP-1) was built on top of the STP in 1990
and is still in operation today. On-site tests conducted for HMC in 2009 determined that the
radon flux from EP-1 was 1.13 pCi/m2-sec, according to a draft report prepared by consultants to
HMC (Simonds et al., 2009). Evaporation Pond #2 (EP-2) is sandwiched between EP-1 on the
east and the East and West Collection Ponds on the west. Exposed tailings and unwetted berms
on the ponds are sources of radon.
2.6.2 Effluent Spraying. Spraying of pond effluent by Homestake to increase evaporation of
wastewater generated by the ground-water remediation system may also be a source of radon and
radon progeny, as noted in both the November TASC Report (pp. 18-19) and in the DRSE Report
(pp. iv, 38). Deposition of precipitates from the high-salinity wastewater onto the berms and
sides of EP-1 and EP-2 was documented in photographs taken by Wm. Paul Robinson and
appended to Mr. Robinson's testimony in the January 2010 hearing on DP-725 (Robinson, 2010;
slides 13, 14, 17, 18; attached hereto as Appendix A). No radiochemical or trace-element data
for the precipitates have been disclosed, a concern noted in the first Remediation System
Evaluation sanctioned by EPA Region 6 (EQM, 2008, p.35). The extent of deposition of
precipitates from the spraying is unclear from an examination of uranium and radium-226
concentrations in soils sampled east of EP-1 and State Route 605. Those concentrations are
shown in a map of the area provided by Homestake at the January 12-13, 2010 hearing on DP-725
(Baker, 2010c), and included in this report as Figure 4. A radium-226 concentration of 9
picoCuries per gram (pCi/g) was detected in the first six inches of soil at sampling location EP-4,
and a uranium concentration of 13 milligrams per kilogram dry weight, or parts per million
(mg/kg-dw and ppm), was detected in the first six inches of soil at nearby sampling location EP-1.
As discussed in Section 2.6.1.2 below, these concentrations are not considered to be within the
range of background absent site-specific data to the contrary.
The TASC Report (p. 18) noted that local residents had reported in a letter to NMED in 2008
that sprays were being blown beyond the perimeter of the evaporation ponds. More recently,
residents of the adjacent neighborhoods reported observing the effluent spray "drifting" into the
community, and provided photographs to document their observations and concerns. (See,
NMED Secretary, 2010; testimonies of Jonnie Head, pp. 291-292, Mark Head, pp. 294-295, and
John Boomer, pp. 297-299.) The first RSE report concluded that the "completion elimination"
of spraying "seems appropriate," given the reports of local residents and "the potential for human
health and environmental exposure" (EQM, 2008, p. 48).
DP-725, issued as amended by NMED on April 12, 2010, is conditioned to require HMC to
"operate the forced spray system such that the spray remains within the confines of the ponds to
the extent practicable" (NMED, 2010, Condition 8, p. 6). The permit also requires HMC to
submit to NMED a plan that outlines the specific atmospheric conditions, such as wind speeds
and wind directions, under which the sprayers would not be operated or would automatically
-------
shut off (Ibid.). Neither DP-725 nor SUA-1471, the NRC license for the facility, currently
contains specific limitations on sprayer operations.
As soon as possible, Homestake should conduct and submit to NMED, NRC and EPA
radiochemical analyses of precipitates deposited by the sprayers on the berms of the evaporation
ponds. Data on particulates detected at the seven perimeter air monitors should be analyzed to
determine if radionuclide levels are correlated with wind patterns (velocities and directions)
and/or spraying events. Minimally, DP-725 and SUA-1471 should be amended to prohibit
spraying when weather conditions would cause mists and precipitates to be deposited outside of
the perimeters of the ponds. The final RSE report should assess whether, based on existing
monitoring data, effluent spraying is protective of public health.
2.6.3 Contaminated Soils. Another source of radon at the HMC site would be contaminated
soils. A wide area of contaminated soils located north, northeast and east of the LTP were
excavated in 1993-1995 to meet NRC and EPA cleanup standards. Data presented by HMC at
the January 2010 public hearing on DP-725 showed 7 ppm uranium and 6 pCi/g radium in soils
near the location of HMC #5 (Figure 4). These concentrations may or may not be in the range
of normal levels for the alluvial soils that cover the San Mateo Creek drainage area around the
HMC site. For comparison, uranium levels in undisturbed soils located on non-uraniferous
Cretaceous rocks in Church Rock, Coyote Canyon, Nahodishgish and Pinedale chapters of the
Navajo Nation ranged from 0.3 ppm to 2.61 ppm, based on nearly 70 sampling points (Shuey et
al., 2007; deLemos et al., 2008). Crustal average radium concentrations are widely reported in
the published literature to be around 1 pCi/g. The EPA's clean-up standard for soils
contaminated by windblown uranium mill tailings is 5 pCi/g radium-226 in the first 15
centimeters of soil, excluding background. (See, 40 CFR 192.32.)
2.6.4 Subdivisions Radon Study and 1989 EPA ROD. EPA's 1989 ROD for the Radon
Operable Unit listed building materials and soils under homes as possible sources of indoor and
outdoor radon (EPA 1989, p. 8). However, the ROD stated that gamma radiation surveys turned
up no evidence that radioactive materials were used in home construction. Uranium and radium
levels in soils collected from beneath and adjacent to homes with elevated indoor radon levels
"were indicative of background levels and provided no evidence that tailings were significant in
the soil in the vicinity of these residences" (EPA 1989, p. 9). Despite this finding, the ROD
states that "the primary source of indoor radon in homes in the subdivisions is local soil which
emits radon gas." Results of the soil monitoring cited to conclude that soil uranium and radium
levels "were indicative of background" were not provided in the ROD, and there was no
indication given in the ROD that soil-gas experiments were conducted.
2.6.5 Aerial Radiation Surveys, 2009. In fall 2009, contractors to EPA Region 6 conducted
aerial gamma radiation surveys in several subregions of the Grants Mineral Belt, including in the
vicinity of the HMC site. A draft report containing color maps and orthophotomosaics
documenting gamma radiation rates and uranium-in-soil concentrations was released for public
comment in January 2010 (EPA 2010a). Images 14, 26, 38 and 53 of the report cover the
residential and agricultural areas located south and southwest of the HMC site. The overflights
touched the southern half of EP-1 and the edge of EP-2, and these locations are easily discernible
on the maps because they have colors representing higher gamma activity levels or higher
uranium concentration levels. While precise locations of elevated gamma radiation and uranium
cannot be discerned from these maps because of their large scale, the color contours that
represent radiation levels do not identify activities or concentrations that would indicate the
-------
presence of an anthropogenic source or sources of radiation and uranium in the residential areas
near the HMC site. In fact, some of the images suggest that soils in the residential area exhibit
uranium in concentrations within the natural range. Image 38, for instance, shows colors
indicating uranium concentrations in soils in the residential areas of less than 4 pCi/g, compared
with colors indicating concentrations >9 pCi/g at the edge of the HMC evaporation ponds.
2.6.6 Inventory Needed of All Radon Sources. The only source of human-made or
technologically enhanced, naturally occurring radioactive materials in the vicinity of the
subdivisions is the HMC site, including its crop irrigation plots located northwest and west of
Pleasant Valley Estates. All other anthropogenic sources of radon — abandoned uranium mines
and closed uranium mills — are located six miles east, six to seven miles north, and four to five
miles west of the community, according to the New Mexico Mining and Minerals Division
uranium mine database (NMMMD, 2009). As noted in the DRSE Report (p. 42), EPA Region 6
is planning to conduct a new round of environmental sampling in the neighborhoods next to the
HMC site later this year in support of a new risk assessment. Minimally, the assessment should
include outdoor and indoor radon monitoring, soil surveys for gamma radiation and uranium and
radium concentrations, surveys of structures for indications of the use of contaminated materials,
an inventory of natural and human-made sources of radioactive materials, and recalculation of
radiation doses to the public. An objective of the assessment should be a complete inventory of
all sources of radon to further investigate why levels exceeding 1 pCi/1-air have persisted in the
neighborhoods next to the HMC site for more than 35 years.
3.0 Air Monitoring Issues and Dose Calculations
3.1 Adjustments in Current Monitoring System. As noted in the Overview of these
comments, the principal objective of HMC's air monitoring program is to determine compliance
with NRC's 100-mrem/y dose limit to the nearest member of the public exposed to releases of
radioactive materials from licensed activities (DRSE Report, Section 7.2.1, p. 36). HMC
operates the eight perimeter air monitoring stations to measure airborne concentrations of radon
and radioactive particulates of uranium, thorium-230 and radium-226, and direct gamma
radiation rates. While the DRSE Report states (p. 37) that the eight monitors meet the minimum
requirements of NRC Regulatory Guide 4.14, the report also notes thatNRC Regulatory Guide
4.14 requires monitoring for lead-210, which is not presently being done by HMC. HMC should
begin monitoring for Pb-210 in parti culates immediately or provide an explanation of why it is
not required or why HMC is exempt from doing so.
The NRC Regulatory Guide 4.14 (Section 2.1.2) also requires that "[a]ir particulate samples
should be collected continuously at.. .the residence or occupiable structure within 10 kilometers
of the site with the highest predicted airborne radionuclide concentration..." As noted
previously, no air monitoring for radon or other radionuclides is being conducted outside of
HMC's restricted area boundary, with the exception of uranium in soils at the two crop irrigation
plots located 1.5 and 2.5 miles west and southwest of the LTP. Absent a specific legal or
technical reason not to select a monitoring site next to a residence., HMC should consult with
BVDA, EPA and NRC to propose and select a suitable monitoring location in Murray Acres or
Broadview Acres.
The DRSE Report (p. 37) also points out that HMC furnishes no meteorological data to support
its air monitoring program. However, HMC has acknowledged that it maintains an on-site
meteorology station from which it gathers data on wind speeds, wind directions, ambient
-------
temperature and other atmospheric conditions. In the January 2010 public hearing on DP-725,
HMC presented a wind rose diagram that showed the highest frequency of winds moving from
the northeast across the tailings piles toward the community to the southwest. (A copy of this
diagram is contained in Figure 5.) While those "northeasterlies" appear to travel at less velocity
than winds coming from the west and southwest, their presence at the HMC site may explain
why high radon levels have been observed at monitor stations HMC #4, HMC #5 and HMC #6.
As suggested in the DRSE Report (p. 37), the LTP itself may act as a funnel carrying low-lying
wind currents toward the community.
HMC should compile and report all previous meteorological data, and commit to including all
future meteorological data in its SAEMRs. HMC should also undertake a study of localized
wind patterns to determine if the tailings piles or other land features contribute to a channeling of
currents into the adjacent community. HMC also should establish a met station in the residential
area, perhaps co-located with a new air monitoring station as recommended above. The final
RSE Report should include these expanded recommendations.
3.2 Assumptions Influencing Calculation of the TEDE. To demonstrate compliance with the
NRC dose limit, HMC calculates the TEDE from all releases of radioactive materials on an
annual basis. The calculation and rationale for its assumptions are contained in Attachment 4 of
each SAEMR, titled "Annual Effective Dose Equivalent to Individuals of the Public" (HMC,
2000-2009). The dose from radon exposure dominates the TEDE calculation; contributions to
the TEDE from particulate emissions and direct gamma rates make up a small portion of the
dose. The DRSE Report (pp. iv, 38) questions HMC's use of certain values for two assumptions
that significantly influence the TEDE calculation: the residential occupancy factor (OF) and the
radon-radon daughter equilibrium factor (EF).
3.2.1 Occupancy Factor (OF). The RSE Team cites NRC staff guidance that requires use of an
OF of "unity," or 1.0, because "10 CFR 20.1302 (b) (2) (ii) involves the assumption that an
individual is continually present in the area." (See, http://www.nrc.gov/about-
nrc/radiation/protects-you/hppos/qa68.html.) HMC cites an NRC technical document (NUREG-
5512, p. 6.37) for its use of an OF of 0.75 (HMC, 2000-2009, Attachment 4, p. 1).
Notwithstanding the NRC staff technical position, the time and activity patterns of many
residents living in the vicinity of the HMC site warrants use of an occupancy factor of 1.0. The
character of the surrounding neighborhoods is semi-rural and agricultural. Most local residents
engage in outdoor activities related to farming and gardening, tending to livestock, and raising
and caring for horses. Whether working indoors or outdoors, they tend to be in the vicinity of
their homes most of the time.
3.2.2 Equilibrium Factor (EF). The EF refers to the proportion of radon activity that comes from
radon's short-lived decay products, called "progeny" or "daughters." As radon-222 decays after
being emitted from a source, its decay progeny takes time to "catch up." Distance and time
dictate how rapidly the progeny come into equilibrium with the parent. Eventually, radon will be
present in an equal proportion with its progeny; in that case, the radon-radon progeny
equilibrium is 100 percent or 1.0.
In every SAEMR submitted to NRC and NMED since at least 2000, HMC has used an EF of 0.2
(20 percent) based on the same rationale:
-------
"Since the nearest residence is within a few hundred feet of the site perimeter and within 3,500
feet of the major source of radon, the radon daughter equilibrium should be low. We have
selected 20 percent radon daughter equilibrium as an estimate for use in the calculations."
(HMC, 2000-2009; see, SAEMR dated December 31, 2009, Attachment 1, p. 3; NRC
Document No. ML 100970422.)
Verifiable and site-specific EFs can be calculated from radon and radon progeny concentrations
measured in air. Three of the six radon studies listed in Table 1 included estimated EFs based
on air monitoring data. Table 4 summarizes the technical bases for these estimates. The
estimates in the studies ranged from 28 percent to 73 percent. The 28 percent EF estimated by
Millard and Baggett (1984, p. 2) was for the closest residence to the LTP. Indoor and outdoor
radon levels exceeding 2.0 pCi/1 were observed in and around homes located more than 1.5 miles
west and southwest of the closest residence in the 1989 Subdivisions Radon Study (HMC, 1989;
USEPA 1989, Tables 1 and 2). The increased travel time and distance from the radon source at
FDVIC to residences in Pleasant Valley and Valle Verde Estates would allow increased in-growth
of radon daughters, increasing the EF.
HMC provides no calculations to support its choice of an equilibrium factor of 0.2, and none of
the historic studies examined for these comments justify the use of an EF of 20 percent. The 50
percent factor estimated by NMEID staff based on results of the 1978-1980 Radon Study is
technically justifiable and more conservative from a public health perspective.
3.2.3 Effects of OF and EF on TEDE Calculations. The November 2009 TASC Report (Table
2, p. 17) demonstrated how selection of an inflated background radon concentration acts to
reduce the TEDE and facilitate compliance with the 100-mrem/y rule. The TASC Report also
showed that a low radon-radon daughter EF also diminishes the final dose calculation (TASC,
2009, Appendix B).
The November 2009 TASC analysis can now be updated to show the effects of overstating
background radon levels and underestimating the OF and EF on the TEDE calculation. Table 5
below presents HMC's 2009 TEDE calculation as the "base case" - a "background" radon level
of 1.3 pCi/1, an OF of 0.75 and an EF of 0.2. As the background level is reduced and the OF and
EF are increased to 1.0 and 0.5, respectively, the calculated doses exceed the 100-mrem/y limit
by up to four times. Even if an inflated background level is retained but higher occupancy and
equilibrium factors are used, the TEDE exceeds the 100-mrem/y limit. As suggested by the RSE
Team, HMC should reassess all input parameters to the TEDE calculation. NRC staff should
review all assumptions and rationales presented by HMC in the annual TEDE calculation
provided in the semi-annual environmental monitoring reports.
4.0 Public Health Risks
Radon and its decay products are well-documented radiotoxi cants that attack human and animal
cells with high linear-energy transfer alpha particles the size of helium nuclei. More than a
dozen epidemiological studies of underground uranium miners has demonstrated substantial
increased risks of lung cancer and lung cancer mortality from exposure to radon and radon
progeny (see, e.g., Samet et al., 1984; Wagoner et al., 1975). These effects have been
demonstrated in the largely non-smoking Navajo uranium miner cohort (see, e.g., Gilliland et al.,
2000; Roscoe et al., 1995); cigarette smoking has been identified as having a multiplicative
effect on incidence and mortality. Studies of uranium miners have been applied to measured
10
-------
levels of radon indoors to generate estimates of the impact of indoor radon on lung cancer
incidence and mortality (Samet and Maple, 1998). EPA (2010), for instance, estimates that
14,000 to 21,000 lung cancer cases result from exposure to indoor radon annually in the United
States, and that radon ranks second only to cigarette smoking as the leading cause of lung cancer
in the United States. The World Health Organization (WHO, 2009) recently recommended a 33
percent decrease in the indoor radon "action level," from 4 pCi/1 to 2.7 pCi/1, in recognition of
the fact that "there is no known threshold concentration below which radon exposure presents no
risk. Even low concentrations of radon can result in a small increase in the risk of lung cancer."
For these reasons, HMC, EPA, NRC and all other stakeholders should be concerned about
chronic exposure to levels of radon that have averaged nearly 2 pCi/1 in the residential areas near
the HMC site since at least the mid-1970s. The lung cancer risk at this level is significant. As
shown in Table 6, a nonsmoker exposed to 2 pCi/1 of radon indoors has a lifetime lung cancer
risk of 4 in 1,000, or 1 in 250. A person exposed to 4 pCi/1 who is not a smoker has a lifetime
lung cancer risk of 7 in 1,000, or 1 in 143. (These cancer risk levels are high compared with the
range at which EPA usually regulates carcinogens: from 1 in 1 million chance to 1 in 10,000.)
A smoker or a former uranium miner faces even greater risks. To put those numbers into
perspective, BVDA members estimate that about 300 people live in the subdivisions that lie in
the shadow of the Homestake mill tailings site. (See, slides 23 and 24 of Appendix A.)
Accordingly, one to two residents could contract lung cancer during their lifetimes from long-
term exposure to the levels of outdoor and indoor radon observed in the community.
The final RSE Report should review the public health risks associated with chronic exposure to
levels of radon observed in the community. Furthermore, it is advisable for the regulatory
agencies to identify sources of funding for health studies, and to engage uninvolved third-party
organizations with appropriate credentials to design and implement health studies in the affected
community. Facilitation of health studies could be done through the RSE Advisory Committee,
which includes BVDA members. This approach would help ensure that all stakeholders have a
part in selecting the health study providers.
5.0 Recommendations
All recommendations contained in these comments are consolidated in this section to facilitate
their review and consideration.
5.1 Environmental Monitoring.
The DRSE Report should be revised to recommend that —
(i) HMC compile, summarize and report all fenceline radiological air monitoring data from the
1980s and 1990s. These data are expected to be stored in hard copies in the NRC's public
document repository.
(ii) Any new air monitoring stations be sited consistent with locations of monitors that had
average annual radon concentrations of less than 0.7 pCi/1-air, which is the upper range of
average levels reported in previous studies.
(iii) The planned EPA Region 6 risk assessment include outdoor and indoor radon monitoring,
soil surveys for gamma radiation and uranium and radium concentrations, surveys of structures
11
-------
to detect the use of contaminated materials, and an inventory of natural and human-made sources
of radioactive materials. Monitoring of radon at HMC's fenceline monitoring stations should be
done concurrently with air monitoring in the residential areas.
(iv) EPA-6 consider hiring a community member to serve as a liaison between the community
and EPA and its contractors during field studies associated with the assessment and at the time
results of the risk assessment are presented to the community.
(v) EPA Region 6 review and reconsider the findings, conclusions and recommendations of the
1989 Record of Decision of the Radon Operable Unit in light of the findings of new
environmental monitoring conducted as part of the planned risk assessment and by HMC under
its routine and expanded monitoring program.
(vi) HMC comply with NRC Regulatory Guide 4.14 and immediately begin monitoring Pb-210
in particulates measured at its eight air monitoring stations.
(vii) HMC establish at least one air monitoring station in the residential area southwest of the
site, including consultation with BVDA, EPA and NRC before selecting a suitable residential
monitoring location. Consideration should be given to establishing more than one air monitoring
station in the residential area to provide an appropriate geographic distribution that takes into
account local wind speeds and directions, and possible contributions to radiation releases from
HMC's two irrigation plots located west of Valle Verde Estates.
(viii) HMC compile and report all previous meteorological data, and commit to including all
future meteorological data in its Semi-annual Environmental Monitoring Reports. The DRSE
Report should further recommend that HMC undertake a study of localized wind patterns to
determine if the tailings piles or other land features contribute to a channeling of currents into the
adjacent community.
(ix) HMC establish a meteorological station in the residential area. The residential air
monitoring station recommended in Section 5.1 (vii) above could be co-located at a new
residential meteorological station. The residential meteorological station should be capable of
measuring wind speeds and directions and ambient temperature and pressure.
5.2 Effluent Spraying:
The DRSE Report should be revised to recommend that —
(i) Homestake conduct and submit to NMED, NRC and EPA radiochemical analyses of
precipitates deposited by the sprayers on the berms of the evaporation ponds as soon as possible.
(ii) Data on particulates detected at the seven perimeter air monitors be analyzed to determine if
radionuclide levels are correlated with wind patterns (velocities and directions) and/or spraying
events.
(iii) DP-725 and SUA-1471 be amended to prohibit spraying when weather conditions would
cause mists and precipitates to be deposited outside of the perimeters of the ponds.
(iv) An assessment be conducted on whether existing monitoring data are adequate to determine
12
-------
if effluent spraying is protective of public health. If the RSE Team finds that existing monitoring
data are not adequate to determine if effluent spraying is protective of pubic health, the final
report should identify the scope of a data-gathering program needed to make such a
determination.
5.3 Dose Calculations. The DRSE Report should recommend that HMC reassess all input
parameters to the calculation of the Total Effective Dose Equivalent (TEDE), including and
especially the occupancy factor and the radon-radon daughter equilibrium factor. The DRSE
Report should further recommend that the NRC staff review all assumptions and rationales
presented by HMC in the annual TEDE calculation provided in the semi-annual environmental
monitoring reports.
5.4 Public Health Risks. The DRSE Report should review the public health risks associated
with chronic exposure to levels of radon observed in the community. The planned EPA risk
assessment should include a summary of historic and current radon levels around the HMC site
and in the community, and calculate doses and respiratory risks using those data. All
management alternatives to mitigate or eliminate exposures from anthropogenic sources of
radiation, heavy metals and other contaminants should be fully and fairly considered.
5.5 Public Health Studies. The DRSE Report should recommend that HMC, EPA, NRC and
NMED identify funding for health studies in the communities, and work with BVDA to identify
uninvolved third-party organizations with appropriate credentials to design and implement health
studies in the affected community. The RSE Advisory Committee, which includes BVDA
members, may be an appropriate vehicle in which to begin these discussions to ensure that all
stakeholders have a part in identifying funding sources and recommending health study
providers.
13
-------
6.0 TASC Contact Information
E2 Inc. Project Manager and Work Assignment Manager
Terrie Boguski, P.E.
913-780-3328
tboguski@e2inc. com
Wm. Paul Robinson and Chris Shuey, TASC Subcontractors
Southwest Research and Information Center
P.O. Box 4524, Albuquerque, NM USA 87196
505-262-1862
sricpaul@earthlink.net
sric.chris@earthlink.net
E2 Inc. Program Manager
Michael Hancox
434-975-6700, ext 2
mhancox@e2inc. com
E2 Inc. Director of Finance and Contracts
Briana Branham
434-975-6700, ext 3
bbranham@e2inc. com
E2 Inc. TASC Quality Control Monitor
Paul Nadeau
603-624-0449
pnadeau@e2inc. com
14
-------
7.0 References
Buhl, et al., 1985. Thomas Buhl, Jere Millard, David Baggett, Sue Trevathan. Radon and Radon
Decay Product Concentrations in New Mexico's Uranium Mining and Milling District. Santa
Fe: New Mexico Environmental Improvement Division; March.
Baker, 2010c. Exhibit HMC 36D, "Soil Assessment Sample Results Uranium and Ra-226,"
attached to testimony of Kenneth L. Baker, in the Matter of the Application of Homestake
Mining Company for Groundwater Discharge Permit, DP-725, Renewal and Modification,
January 12.
Baker, 201 Ob. Exhibit HMC 36C, "Environmental Monitoring Stations," attached to testimony
of Kenneth L. Baker, in the Matter of the Application of Homestake Mining Company for
Groundwater Discharge Permit, DP-725, Renewal and Modification, January 12.
Baker, 2010a. Exhibit HMC 36B, "Meteorological Data Wind Rose," attached to testimony of
Kenneth L. Baker, in the Matter of the Application of Homestake Mining Company for
Groundwater Discharge Permit, DP-725, Renewal and Modification, January 12.
deLemos, et al., 2008. J. deLemos, B. C. Bostick, A. Quicksall, J. Landis, C. C. George, N.
Slagowski, T. Rock, D. Brugge, J. Lewis, J.L. Durant. Rapid Dissolution of Soluble Uranyl
Phases in Arid, Mine-Impacted Catchments near Church Rock, NM. Environmental Science and
Technology, 42:3951-3957.
DRSE Report, 2010. Draft Report February 2010: Focused Review of Specific Remediation
Issues - An Addendum to the Remediation System Evaluation for the Homestake Mining
Company (Grants) Superfund Site, New Mexico. Prepared for U.S. Environmental Protection
Agency Region 6 by US Army Corps of Engineers, Environmental and Munitions Center of
Expertise; February 15.
Eadie, et al., 1976. G. G. Eadie, R. F. Kaufmann, D. J. Markley, R. Williams. Report of ambient
outdoor radon and indoor radon progeny concentrations during November 1975 at selected
locations in the Grants Mineral Belt, New Mexico. Las Vegas, NV: U.S. Environmental
Protection Agency, Office of Radiation Programs, ORP/LV-76-4, June.
EPA, 2010b. Radon Health Risks: Exposure to Radon Causes Lung Cancer in Non-smokers and
Smokers Alike, www.epa.gov/radon/healthrisks.html; February 22.
EPA, 2010a. Aerial Radiological Survey of the Grants and Cebolleta Land Grant Areas in New
Mexico. Prepared by Dynamic Corp. for U.S. Environmental Protection Agency Office of
Emergency Management, National Decontamination Team (Cincinnati), January.
EPA, 2006. Second Five-Year Review Report for Homestake Mining Company Superfund Site,
Cibola County, New Mexico. Dallas: U.S. Environmental Protection Agency, Region 6,
September.
EPA, 2001. First Five-Year Review Report for Homestake Mining Company Superfund Site,
Cibola County, New Mexico. Dallas: U.S. Environmental Protection Agency, Region 6,
September.
15
-------
EPA, 1989. U.S. Environmental Protection Agency. Record of Decision, Homestake Mining
Company Radon Operable Unit, Cibola County, New Mexico, September 1989.
EQM, 2008. Environmental Quality Management, Inc. Draft Final Remediation System
Evaluation Report for the Homestake Superfund Site, Milan, New Mexico. Prepared for U.S.
Environmental Protection Agency Office of Research and Development (Cincinnati) and EPA
Region 6 Superfund Program, December 19.
George and Breslin, 1978. A. C. George and A. J. Breslin. The Distribution of Ambient Radon
and Radon Daughters in Residential Buildings in the New Jersey-New York Area. Natural
Radiation Environment III, Volume 2, p. 1272. Springfield, VA: National Technical Information
Service.
Gilliland et al., 2000. Gilliland FD, Hunt WC, Pardilla M, Key CR. Uranium mining and lung
cancer among Navajo men in New Mexico and Arizona, 1969 to 1993. Journal of Occupational
and Environmental Medicine; 42(3):278-83, March.
Homestake Mining Company of California (2000-2009). Semi-annual Environmental
Monitoring Reports (SAEMR) for years 1999-2009; transmitted to U.S. Nuclear Regulatory
Commission by HMC letters dated Feb. 24, 2000; Aug. 15, 2001; Feb. 21, 2002; Aug. 28, 2002;
Feb. 26, 2003; Aug. 27, 2003; Feb. 24, 2004; Aug. 30, 2004; Feb. 24, 2005; Aug. 30, 2006; Feb.
20, 2007; Aug. 20, 2007; Feb. 20, 2008; Aug. 20, 2008; Feb. 25, 2009; Dec. 31, 2009.
Homestake Mining Company, 1989. Subdivisions Radon Study, Feasibility Study Report.
Homestake Mining Company Grants Operation, June.
Millard and Baggett, 1984. Jere B. Millard, David T. Baggett. Radiological Assessment of the
Populated Areas Southwest of the Homestake Mining Company Uranium Mill. Santa Fe: New
Mexico Environmental Improvement Division, Radiation Protection Bureau, August.
NMED, 2010. Discharge Permit DP-725, amended April 12, 2010. Transmitted by certified
letter from William C. Olsen, NMED Ground-water Quality Bureau, to Alan Cox, Homestake
Mining Company, April 12.
NMED Secretary, 2010. State of New Mexico, Before the Secretary of Environment, No.
GWQB 09-35(P), In the Matter of the Application of Homestake Mining Company for
Groundwater Discharge Permit, DP-725, Renewal and Modification. Transcript of Proceedings,
Volume I; testimonies of John Boomer, Arthur Gebeau, Candace Head-Dylla, Jonnie Head,
Mark Head; January 12-13.
NMEI, 1974. An Environmental Baseline Study of the Mount Taylor Project Area of New
Mexico. New Mexico Environmental Institute (Martha A. Whitson, Thomas O. Boswell);
prepared for Gulf Minerals Resources Co., Project No. 3110-301, March.
NMMMD, 2009. Uranium mine database. Available from the New Mexico Mining and
Minerals Division, Santa Fe.
16
-------
Robinson, 2010. BVDA Exhibit 2, "Photographs, Maps and Diagrams Supplementing Direct
Testimony of Wm. Paul Robinson on behalf of Bluewater Valley Downstream Alliance," in the
Matter of the Application of Homestake Mining Company for Groundwater Discharge Permit,
DP-725, Renewal and Modification, January 12.
Roscoe et al., 1995. Roscoe RJ, Deddens JA, Salvan A, Schnorr TM. Mortality among Navajo
uranium miners. American Journal of Public Health; 85(4):535-40, April.
Samet and Mapel, 1998. Samet J, Mapel DW. Diseases of Uranium Miners and Other
Underground Miners Exposed to Radon. Chapter 98 in Environmental and Occupational
Medicine, WMRom, ed. Philadelphia: Lippincott-Raven Publishers, 1307-1315.
Samet et al., 1984. Samet JM, Kutvirt DM, Waxweiler RJ, Key CR. Uranium mining and lung
cancer in Navajo men. New England Journal of Medicine; 310(23): 1481-4, June 7.
Shuey, et al., 2007. C. Shuey, J. deLemos, C. George. Uranium mining and community
exposures on the Navajo Nation. Presentation to the annual meeting of the American Public
Health Association (Washington, DC), November 7.
Simonds, et al., 2009. M.H. Simonds, M.J. Schierman, K.R. Baker. Radon Flux from
Evaporation Ponds. Draft paper, 2009. (Available from Homestake Mining Co.)
TASC, 2009. "Summary and Review of Application for Modification and Renewal of NMED
Discharge Permit DP-725, Effluent Disposal Facilities for the Ground Water Remediation
System at the Homestake Mining Company, Grants Reclamation Project, Milan, N.M. Prepared
by E2 Inc. for U.S. Environmental Protection Agency Region 6 and Bluewater Valley
Downstream Alliance, November 18.
Wagoner et al., 1975. Wagoner JK, Archer VE, Gillam JD. Mortality of American Indian
Uranium Miners. Proceedings XI International Cancer Congress (Bucalossi P, Veronesi U,
Cascinelli N, eds.), 3:102-107; ExcerptaMedica International Congress Services No. 351.
WHO, 2009. World Health Organization, Geneva, Switzerland. WHO Handbook on Indoor
Radon - a Public Health Perspective. Available at,
http://www.who.int/mediacentre/factsheets/fs291/en/index.html.
17
-------
Table 1.
Major Radon Monitoring Studies in the Grants Mineral Belt
and Surrounding the Homestake Mining Company Grants Superfund Site, 1972-2009
Period
Organization(s)/
Reference(s)
Content
Monitors
1972-1973
New Mexico
Environmental Institute
(NMEI, 1974) for Gulf
Minerals Resources
Radon baseline study with
aircraft-based investigation of
effects of temperature inversions
on radon levels in San Mateo,
New Mexico; part of
environmental baseline study for
proposed Mt. Taylor Uranium
Mine
Taplex high-volume air
samplers with discharge to
scintillation cell (p. 68)
1975
(November)
EPA Office of Radiation
Programs, Las Vegas,
Nev. (Eadie et al.,
1976)
Study of outdoor radon and
indoor radon progeny levels at
10 sites in the Grants Mineral
Belt
48-hr bag collection with
discharge of air to
scintillation cell
1978-1980
New Mexico
Environmental
Improvement Division
(Buhletal., 1985)
Study of outdoor radon levels at
27 sites, 21 sites in the
Ambrosia Lake-Milan-Bluewater
region and six sites in places
where uranium mining and
milling had not previously
occurred
Outdoor radon: 48-hr bag
collection with discharge of
air to scintillation cell;
Indoor radon progeny:
Radon Progeny Integrating
Sampling Units provided
by EPA
1983-1984
NMEID(Millardand
Baggett, 1984)
Radiological assessment of
residential areas southwest of
the HMC site with monitors
located in Murray and
Broadview Acres and villages of
San Mateo and Bluewater
PERMs (Passive
Environmental Radon
Monitors) provided by EPA
1987-1988
Homestake Mining
Co. (Carter 1988,
HMC 1989, USEPA,
1989)
Subdivisions Radon Study
conducted in 59 homes and at
28 outdoor stations
Initial screening: three-day
charcoal canisters; long-
term monitoring with
Terradex Track-Etch
monitors
1999-2009
Homestake Mining
Co. (HMC, 2000-
2009)
Radon data from HMC's seven
perimeter air monitoring sites
and one background monitor
station, extracted from HMC's
SAEMRs
Terradex Track-Etch
monitors
18
-------
Table 2.
Summary of Average Annual Radon Levels at Background and Non-Background
Locations in Ambrosia Lake-Milan Uranium Mining District, 1972-2009
(all concentrations in picocuries per liter-air)
Year/
Period
1972-73
Nov.
1975
1978-79
1979-80
1978-80
1983-84
1987-88
(15 mo.)
1999-
2009*
2010
Study Area
San Mateo, NM
Ambrosia Lake-
Milan
Ambrosia Lake-
Milan
Ambrosia Lake-
Milan
Bluewater Lake,
Cebolleta,
Crownpoint, Gulf
Mill Site, Nose
Rock, San Mateo
San Mateo and
Bluewater Village
Residential area
south and
southwest of
HMC site
Perimeter of
HMC-licensed
area
United States
Background
# monitors
(# samples)
3
(135)
5
(5)
9
(122)
10
(187)
6
(115)
2
(52)
28
(112)
HMC #16
(21)
Not given
Average Rn
(range)
0.19
(0.08-.59)
0.71±0.47
(0.11-1.2)
0.57±0.69
(0.10-1.12)
0.50±0.58
(0.14-0.81)
0.19±0.02
(0.13-0.25)
0.35±0.02
(no range)
Non-background
# monitors
(# samples)
None
5
(5)
AL: 6 (1 1 0)
HMC: 3 (53)
AC: 2 (38)
AL:6(136)
HMC: 3 (67)
AC: 2 (42)
MA and BA:
5(130)
Average
Rna (range)
None
2.58±0.73
(1.9-3.6)
3.20±2.53
(2.01—4.23)
1.83±1.24
(1.55—2.01)
1.06±0.75
(0.76-1.37)
4.66±2.89
(3.23-6.40)
1.51±1.02
(1.51—1.89)
0.87±0.64
(0.78-0.95)
1.62
(no sd or
range given)
1.9±0.4D
(range of corrected Rn values, 1.2-2.7)
(range of maximum Rn values, 2.8-8.2)
1.16±0.36
(0.8-2.5)
0.4 (average
outdoor Rn)
HMC #4 1.80±0.33
(20) (1.1-2.4)
HMC #5 1.63±0.32
(20) (1 .2-2.2)
HMC 1.38±.0.35
#1,2,3,6,7d (0.8-2.8)
(100)
n/a n/a
References
GMR: NMEI,
1974
USEPA:
Eadie et al.,
1976
NMEID:
Buhletal.,
1985 (17)
NMEID:
Buhletal.,
1985 (18, 28)
NMEID:
Millard &
Baggett,
1984
HMC:
EPA, 1989
HMC, 2000-
2009
EPA 2010
Abbreviations: AC = Anaconda Co.; AL = Ambrosia Lake Mill (Kerr-McGee Corp./Quivira Mining Co.); BA =
Broadview Acres; GMR = Gulf Mineral Resources; HMC = Homestake Mining Co.; MA= Murray Acres; NMEID =
New Mexico Environmental Improvement Division; sd = standard deviation; EPA = U.S. Environmental Protection
Agency
19
-------
Table 3a.
Ambient Radon-222 Concentrations at HMC Perimeter Air Monitoring Stations, 1999-2009
(all concentrations in picocuries per liter air)
Reference
HMC-SAEMR, 2/24/00
HMC-SAEMR, 8/8/00
EPA, 2001 (Table 4)
HMC-SAEMR, 8/15/2001
HMC-SAEMR, 2/21/02
HMC-SAEMR, 8/28/02
HMC-SAEMR, 2/26/03
HMC-SAEMR, 8/27/03
HMC-SAEMR, 2/24/04
HMC-SAEMR, 8/30/04
HMC-SAEMR, 2/24/05
EPA, 2006 (Table 4)
HMC-SAEMR, 2/24/06
HMC-SAEMR, 8/30/06
HMC-SAEMR, 2/20/07
HMC-SAEMR, 8/20/07
HMC-SAEMR, 2/25/08
HMC-SAEMR, 8/20/08
HMC-SAEMR, 2/25/09
HMC-SAEMR, 12/31/09
HMC-SAEMR, 12/31/09
Year
1999
2000
2000
2001
2001
2002
2002
2003
2003
2004
2004
2005
2005
2006
2006
2007
2007
2008
2008
2009
2009
Period
2nd half
1st half
2nd half
1st half
2nd half
1st half
2nd half
1st half
2nd half
1st half
2nd half
1st half
2nd half
1st half
2nd half
1st half
2nd half
1st half
2nd half
1st half
2nd half
HMC
#1
2.0
1.4
2.2
1.5
1.1
1.3
1.5
1.6
1.7
1.1
1.6
1.2
1.5
1.2
1.7
1.5
1.9
1.4
1.3
1.6
HMC
#2
1.6
1.5
1.6
2.2
1.3
1.6
1.3
2.3
1.5
0.9
1.4
1.8
1.5
1.7
2.0
1.0
1.7
1.6
1.6
1.8
HMC
#3
1.1
1.2
1.2
1.2
0.7
1.1
1.1
1.2
1.1
0.6
1.2
0.9
1.2
1.1
1.0
0.7
1.6
1.4
1.2
1.4
HMC
#4
1.7
1.9
2.0
1.8
1.4
1.6
1.5
1.2
2.3
1.1
1.8
1.8
2.0
2.2
2.1
1.8
2.4
1.8
1.7
1.8
HMC
#5
1.6
1.2
1.8
2.0
1.4
1.3
1.3
1.5
1.5
1.2
1.7
1.4
1.7
2.1
1.8
1.3
1.8
2.2
2.2
1.5
HMC
#6
1.7
1.1
1.1
1.4
1.1
1.5
1.2
0.9
1.6
1.7
1.6
1.4
1.6
1.1
1.4
1.3
1.7
1.6
2.8
1.4
HMC
#7
1.2
1.0
1.1
1.7
1.1
1.1
1.1
1.2
1.4
0.8
1.2
1.3
1.3
1.2
1.3
0.9
1.6
1.3
1.2
1.2
HMC
#16
1.1
0.9
1.1
1.1
1.1
0.9
0.9
0.9
1.0
1.5
1.0
1.2
1.1
1.0
1.0
0.8
1.6
1.3
1.2
1.2
2.5
Table 3b.
Results oft-Test* of Two Samples Assuming Unequal Variance
for Radon Levels in HMC Perimeter Air Monitors
(all concentrations in pCi/l-air)
Station
HMC#1
HMC #2
HMC #3
HMC #4
HMC #5
HMC #6
HMC #7
HMC #16
N
20
20
20
20
20
20
20
21
Mean
1.52
1.60
1.11
1.80
1.63
1.46
1.21
1.16
Std.
Dev.
0.29
0.34
0.24
0.33
0.32
0.40
0.21
0.36
Median
1.50
1.60
1.15
1.80
1.55
1.40
1.20
1.10
Max
2.2
2.3
1.6
2.4
2.2
2.8
1.7
2.5
Min
1.1
0.9
0.6
1.1
1.2
0.9
0.8
0.8
p-value**
<0.002
<0.0004
0.59
<0.0000001
<0.0002
<0.02
0.605
n/a
*Normal distribution of Rn values assumed, based on examination of differences in calculated mean and
median values.
**p is the probability that radon levels at HMC air monitors are significantly different than radon levels in
HMC #16 at a <0.05. p-values in italic signify a significant difference in average radon levels.
20
-------
Table 4.
Radon-Radon Daughter Equilibrium Estimates in Regional Studies
Study (Reference)
1975 EPA Study
(Eadieetal., 1976, p. 9)
1978-1 980 NMEID Study
(Buhletal., 1985, p. 42)
1983-84 NMEID Radiological
Assessment (Millard and
Baggett, 1984, p. 2)
Technical Basis
"Percent Equilibrium" was
calculated for each of the 10
monitoring stations in the study
Outdoor radon was correlated
with indoor radon progeny
concentration
Calculated EF from average wind
speed from HMC tailings to
residences, distance from tailings
to homes, travel time from source
to target for in-growth of radon
daughters
EF Estimate(s)
Range of EF: 40% -129%;
average of all EFs: 73.7%
(0.737)
EF = 50% (0.50)
EF = 28% (0.28)
Also cited study by George and
Breslin (1978) in which an EF of
83% was calculated from outdoor
radon and radon daughter levels.
21
-------
Table 5.
Comparison of HMC-Calculated Total Effective Dose Equivalent (TEDE)
at Nearest-Residence Air Monitoring Station (HMC #4) with Doses Calculated Using
Different Background Radon Values and Different Assumptions
for Occupancy Factor (OF) and Radon-Radon Daughter Equilibrium Factor (EF)
(doses in italics exceed NRC's 10 CFR20.1301(a)(1) limit of 100-mrem/y to member of the public)
Nearest
Residence
Radon
HMC #4
(2009)
pCi/l
1.8
1.8
1.8
1.8
1.8
Back-
ground
Radon
pCi/l
1.3
1.12
0.81
0.53
0.19
Background Station(s)
(Year)
HMC #16 (2009)
NMEID#201 (1979)
(comparable with ave. Rn
level of 1.1 6 in HMC #16)
NMEID#201 (1980)
NMEID#211,#212, #219,
#220, #316, #415(1983)
San Mateo( 1972-73);
Bluewater Lake, Crownpoint,
Gulf Mill Site, San Mateo
(1978-80)
HMC
Base
Case:
OF = 0.75
EF = 0.2
46.3
59.8
83.1
104.1
129.6
OF = 1.0 OF
EF = 0.2 EF
mrem/y
58.8
76.8
107.8
135.8
169.8
= 0.75
= 0.5
102.6
136.3
194.4
246.9
310.7
OF = 1.0
EF = 0.5
133.8
178.8
256.3
326.3
411.3
22
-------
Table 6.
Lifetime Risk of Lung Cancer from Indoor Radon Exposure - Non-smoking and Smoking
(Source: EPA, 2010)
Radon Level
(pCi/l*)
20
10
8
4**
2
1 .3***
0.4
Lifetime Cancer Risk
Among Non-smokers
36 in 1,000(3.6x10"^)
18 in 1,000(1.8x10"^)
15 in 1,000(1.5x10"^)
7 in 1,000(7x10"J)
4 in 1,000(4x10"J)
2 in 1,000(2x10"J)
No risk estimated
Lifetime Cancer Risk
Among Smokers
260 in 1,000 (2.6 x10"n)
150 in 1,000(1.5x10"n)
120 in 1,000(1 .2 x10"n)
62 in 1,000(6.2x10"^)
32 in 1,000(3.2x10"^)
20 in 1,000 (2x10"")
No risk estimated
Remediation
Recommendations
Ventilate your home
Ventilate your home
Ventilate your home
Ventilate your home
Consider ventilating or
fixing your home
Consider fixing your home,
but may be difficult
None recommended
*pCi/l = picocuries per liter air
**EPA "action level" for indoor radon
***Average indoor radon level in United States., according to EPA
23
-------
Figure 1
Air Monitoring Stations at the Homestake Mining Company Superfund Site
(Source: Baker, 201 Ob)
~
HMC#16
EP#3
Legend
D Monitoring Station
,Feet
0 1,2502,500
5,000
HMC#1
HMC#2
HMC#6
HMC#4
r
HMC#3
HMC#7
24
-------
Figure 2.
Average Annual Outdoor Radon Concentrations*
at Background Stations, BVDA Residential Area, and
Nearest-residence Monitor (HMC #4), 1972-2009
Monitoring Years and Locations
25
-------
Figure 3. Mean Radon Levels of HMC Air Samplers, 1999-2009
2.50
0.00
HMC#1 HMC #2 HMC #3 HMC #4 HMC #5 HMC #6 HMC #7 HMC #16
26
-------
Figure 4.
Soil Assessment Sample Results, Uranium and Ra-226
(Source: Baker, 201 Oc)
Uranium and Ra-226 values are displayed for
each sample location and depth. Uranium
results (mg/Kq) are in blue and Ra-226 results
are in black. The depth is shown by which line
the data is on. The first line is the 0 to 6 inch
layer, the second line is the 6 to 12 inch layer,
and the third line is the 12 to 18 inch layer. If
only one or two lines of data are shown then
Legend
Soils Assessment Sample Locations
Sample Depth
• 0-6 inches
A 6-12 Inches
• 12-18 inches
Its are available for only the top one or two
154.1
11 3.6
1 6.2
EP-7 A 4 0-65
2 0.79
27
-------
Figure 5.
Meteorological Data Wind Rose
For Homestake Mining Company Superfund Site
(Source: Baker, 201 Oa)
11 deg.9%
Wind rose data are presented
in circular format. The length
of each "spoke" is related to
the frequency that the wind
blows from a particular
direction per unit time. Each
concentric circle represents a
different frequency, emanation
from 0% at the center and
increasing to 10% at the outer
circle.
WIND SPEED
(m/s)
m >=n/i
I I 8.8-11.1
I I 6.7 - 8fi
I I 3.6- 5.7
^| 2.1- 36
H 0.5- 2.1
Cilms: 0.02%
28
-------
Appendix A
"Photographs, Maps and Diagrams Supplementing Direct Testimony of
Wm. Paul Robinson on behalf of Bluewater Valley Downstream Alliance,"
in the Matter of the Application of Homestake Mining Company
for Groundwater Discharge Permit, DP-725, Renewal and Modification
January 12, 2010
29
-------
STATE OF NEW MEXICO
Before the
SECRETARY OF THE ENVIRONMENT
in the matter of
Renewal and Modification of Discharge Permit 725
Homestake Mining Company
Grants Reclamation Project
January 12, 2010
Photographs, Maps and Diagrams
upplementing Direct Testimony of
.-_
- .
1--..
-••
:!
•-«--- ?' -
on behalf of
.
Bluewater Valley Downstream Alliance
'* " "
;W*---v- -'-, . , .— ;* ,.
.—
--*» .
-------
(1) Proposed
Evaporation Pond 3
(size and location
approximate)
(2) Large Tailings
Pile
(3) Evaporation
Pond 1
(4) Small Tailings
Pile
(5) Evaporation
Pond 2
(6) East Collection
Pond
(7) West Collection
Pond
(8) Reverse
Osmosis Plant
-------
Schematic Diagram Summarizing Flows of Liquids and
Reverse Osmosis Plant Residues to HMC Waste
Management Units for week ending Sept 28, 2009
'ER10C STtflTlMu 7>nuuir»
Source: "Example Weekly Report.pdf" provided by Homestake to RSE QuickPlace website
-------
Homestake Mining Co.
DP-725
Effluent Management Facilities
Waste Characterization and
Monitoring Issues
-------
Chart 1
Volume-Time Plot of Metals Collected from Homestake
Groundwater Remediation System, 1978-2008
U
Mo
Se
120000
Years
-------
Chart 2
Cumulative Accounting of Metals Collected from
HMC Groundwater Remediation System, 1978-2008,
by System Component
1,200,000
1,000,000
800,000
600,000
400,000
200,000
0
Uranium D Molybdenum • Selenium
Groundwater
Tailings Flush
Toe Drains
-------
ChartS:
Constituents Collected from Groundwater
3.1. Sulfate (SO4) Collected from Groundwater at Homestake LTP
Figure 5a. Molybdenum (Mo) Collected from Groundwater at
Homestake LTP
oooooooo
ooooooooo
3.2. Uranium (U) Collected from Groundwater at Homestake LTP
ooooooooo
ooooooooo
3.4. Selenium (Se) Collected from Groundwater at Homestake LTP
ooooooooo
ooooooooo
-------
Chart 4:
Constituents Collected from Tailings Flushing
4.1. Sulfate (SO4) Collected from Tailings Flushing at HMC LTP
1995 1996 1997 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Years
4.3. Molybdenum (Mo) Collected from Tailings Flushing at HMC LTP
1995 1996 1997 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
4000 -
4.2
Uranium (U) Collected from Tailings Flushing at HMC LTP
>
T
1—1
• ~
n
1995 1996 1997 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Years
4.4. Selenium (Se) Collected from Tailings Flushing at HMC LTP
1995 1996 1997 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
-------
Charts:
Constituents Collected from Toe Drains
5.1. Sulfate (SO4) Collected from Toe Drains at Homestake LTP
5.3. Molybdenum (Mo) Collected from Toe Drains at Homestake LTP
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
5.2. Uranium (U) Collected from Toe Drains at Homestake LTP
9000
8000
7000
6000
5000
I
I
4000
3000
2000
1000
0
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
5.4. Selenium (Se) Collected from Toe Drains at Homestake LTP
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
-------
NMEID
Radon
Monitoring
Stations,
1979-1981
(from Buhl, et al.,
1985, p. 13)
8LUEWATER
• External Radiation
• Radon
* Background Radon
• Radon Progeny-
'x Uran i urn Mi nes
!_J Uranium Facilities
^'-•••^ Uran i um Ta i 1 ings
ESS Near Surface
Uranium Mineralization
J GRANTS 1 T? -•
l™ \ *:e*£S* r.«J\ t,
1 uO**0 \ I
v / \ '•—.
%K\ V ^
RAFAEL ^ -x »,
\ )
Mi les
Scale
Figure 3.1 Sampling Locations and Station Numbers
10
-------
NMEID Ambient Rn-222 Levels, 1979-1981
8LUEWATER
• Radon
* Background Radon
^Uranium Kines
dJ Uraniurn Facilities
E3 Ljran i urn Ta i t ings
OMear Surface Uranium
M i ne rali zat ion
Miles
,../"t'y .*-:< /"V":-.. t"%>""r
.,.-!''-£ •'"$ ' H'l?/':i""':.'->::'""^
r vi..../n\j &i£*..;^-r<, *
•§-, '"->,••'„>' -v S 'tv%. '-• i-,
,-' '£ --" :',, AMBROSIA r ,", V'A
-" f%-""7. =-<"KE " "X 'V^0 i,-'-:
• V£V rsf"*'^^? / r>
c-:-v **,V- ^«>v^y,,,
," "" 57T\ r~51 ?= ^'/'. '••'",.•••"
...-•••;'*^W'-- , 3-74'J^ij\ 5.7^^"v;v^?.,,/"\.C.
,, *''- A fcl . '""', /.-'''"''-
MTN5 •:!"<- X.,.-;<^^"' \l.69 i;''."- <-
""W '; 'O. \5 ^ " *'"•""'' SAN M-
* ^•^M5-'-'aSffiWP^->^!lKZ*n^«^
MATEO .
4 ":-
' OJ4 ,;-
Anaconda
0.21
o.si
".-, '--.
™M^':W^ 4 """•
\ °7 '~jt*»f r'
**-
MILAN
,-,GRANTS
*&
^_/SAN RAFAEL
"^
Mi les
Figure 3-2 First Year Radon Averages By Station
Scales
Figure 3.3 Second Year Radon Averages By Station
-------
Homestake Mining Co.
DP-725
Effluent Management Facilities
Waste Management Concerns
Liner Integrity
12
-------
Liner
exposure to
weather and
sludge
(April 2007)
-------
Liner exposure to salinity and weathering, June 2008
(from USEPA RSE-I Report, Dec. 2008)
EP1 showing pumping of water to cover
liner with brine (yellow-white color)
(looking northwest toward LTP)
Right: EP2 liner showing effects
of exposure to air and sun
ECP showing sludge
accumulation (looking south)
-------
Homestake Mining Co.
DP-725
Effluent Management Facilities
Waste Management Concerns
Effluent Spraying
15
-------
Effluent Spray on EP1, April 2004
(Large Tailings Pile, center-right)
-------
Spraying effects, April 2007:
White salt deposits on berms of EP2
(1) Looking SE across EP2
(2) Looking E on north berm of EP2
(3) Looking SW across west berm
of EP2; ECP, homes at top
(4) Looking
W on EP2
toward ECP
-------
Sprayers on EP1, EP2
October 2007
Evaporation Pond #1
Evaporation Pond #2
-------
Effluent Spray over EP1, April 2009
(showing eastern fence line and eastern berm of Small Tailings Pile)
•'
-------
Homestake Mining Co.
DP-725
Effluent Management Facilities
Facility Siting Concerns
20
-------
1 • 2.'-'
STATE OF NEW MEXICO
PROJECT BBA
STATE ENGINEER MR. S. E. REYNOLDS
PORTION OF VALENCIA COUNTY, NEW VE
SCALE OF PHOTOGRAPHY liZO.OOO
SCALE OF INDEX 1:63,360
DATE OF PHOTOGRAPHY 13 AUGUST 96
ABRAMS AERIAL SURVEY CORPORATH
LANSING, MICHIGAN, U. S A
m
r
-------
El
-------
Proximity of Waste Management
Units to Residential Areas
Residences
stf/*-
-
HT*
-%•**
V/:
23
-------
View of Homestake Mill Tailings Site
and Residential Areas, April 2009
(Mt. Taylor in right background)
Approximate
Location, EPS
. \
Large Tailings Pile
-------
Technical Assistance Services for Communities
Contract No.: EP-W-07-059
TASC WA No.: R6-TASC-002
Technical Directive No.: R6-Homestake Mining-03
Observations and Recommendations Regarding the June 18, 2010 Addenda to the
Draft Focused Review of Specific Remediation Issues for the Homestake Mining
Company (Grants) Superfund Site, February 2010
July 22, 2010
I. Introduction
A. This document provides the Bluewater Valley Downstream Alliance (BVDA)
with comments on two addenda to the U.S. Army Corps of Engineers' (USAGE)
"Draft Remediation System Evaluation (Supplement) for the Homestake Mining
Company (Grants) Superfund Site, New Mexico" (DRSE, 2010). One addendum,
referred to in this document as the "Evaporation Addendum," addresses new
Remediation System Evaluation (RSE) Team calculations regarding evaporation
rates, evaporation pond capacities and possible changes in the current ground
water remediation system at the Homestake Mining Company (HMC) site. The
second addendum, the "Carbon Footprint Addendum," discusses options that
involve moving the existing HMC tailings piles to achieve ground water
remediation and site decommissioning and decontamination under both federal
and state authorities. These addenda were provided by the RSE Team to
stakeholders by e-mail on June 18, 2010.
B. The two addenda are understood to be revisions of the DRSE Report, prepared by
the RSE Team on its own initiative to revise its previous calculations on
evaporation rates (and evaporation capacity) and the "carbon footprint" of a
tailings relocation option, and in part as response to comments from some
stakeholders (including BVDA) in the RSE process.
Further clarity regarding the RSE Report process is needed following submittal of
these addenda. It is recommended that the U.S. Environmental Protection Agency
(EPA) and USAGE provide clarification on next steps for the RSE Report.
Possible options include:
1) A second draft RSE report will be issued for comment once the RSE
Team and stakeholders have had a chance to review and respond to
comments on the addenda.
-------
2) The RSE Team will issue a final report, responding not only to
comments on the addenda, but also to comments received in April and
May 2010 from various stakeholders.
3) Some other variation on the path to a final RSE Report.
It is a concern that there have been no RSE Team responses to the May 6, 2010
TASC comments that addressed: (1) elements of the DRSE Report that concerned
the overall effectiveness of the ground water remediation system; and (2)
deficiencies in the current air monitoring program for radionuclides, particularly
radon.
II. General Comments on the June 18th Addenda
A. When read in tandem, the two addenda and the DRSE Report identify many
unresolved issues regarding both the effectiveness of the current ground water
remediation program and the long-term management of a fully remediated site.
To resolve the difficult issues related to current performance and long-term
management, the RSE Team should identify the full range of options in both areas
and the range of additional actions and investigations to define an optimized path
forward for remediation at the HMC site. By treating these portions of the
remediation system optimization separately, the tailings relocation option (or
options, given there are several options that have not been considered by the RSE
Team, as outlined below) is dismissed prematurely prior to demonstration of an
effective ground water remediation system and without the level of scientific
evaluation merited by the complex and challenging conditions and the 50-year
history of ground water contamination at the HMC site.
B. To provide for more thorough consideration of remediation and long-term
management options at the HMC site, the RSE Team should evaluate whether the
existing EPA -Nuclear Regulatory Commission (NRC) Memorandum of
Understanding (MOU) provides an effective mechanism for implementing
remediation optimization. This MOU apparently supplanted the need for a
Remedial Investigation/Feasibility Study (RI/FS) under authority of the
Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) for the "ground-water operable unit" in the mid-1980s. Absent an
RI/FS, the MOU mechanism should be reviewed to ensure that all feasible options
for improving and expediting ground water remediation in the short term and
long-term site management and rehabilitation are considered.
C. When considered together, the contents of the addenda and the DRSE report
would have major implications for the scope and form of the HMC site's
remediation system if they were considered at the level of detail appropriate for
review of alternatives for the "Corrective Action Plan" (CAP) under review by the
NRC since 2006. If the DRSE Report was considered as a set of substantive
comments on the proposed CAP license amendment currently under review by the
-------
NRC, or on the DP-200 application currently under review by the New Mexico
Environment Department (NMED), implications of its suggestions and
recommendations regarding regulatory actions affecting the site could be
thoroughly considered.
D. Since the remediation system evaluation or optimization process under CERCLA
is a science-based initiative based on sound technical approaches, and not a
regulatory-based process, serious consideration of alternatives for the long-term
remediation of the site and the area's ground water must be completed in the
context of the existing NRC license, NMED's ground water discharge permit, or
both concurrently. For these reasons, the RSE Team should specify in the final
RSE Report that the identified optimization opportunities should be subject to a
full-scale analysis as corrective action options, including consideration of all
options for tailings removal and relocation. In addition, the RSE Team should
specify that this analysis should be conducted under authority of the Atomic
Energy Act and the National Environmental Policy Act at the federal level and the
New Mexico Water Quality Act at the state level. It is suggested that the
optimization enhancements identified by the RSE Team be considered as
modifications to the Homestake CAP currently being reviewed by the NRC as a
license amendment. If this is done, the RSE Report could provide a basis for a
"new, hard look" as it provides substantial new information not available during
the review of previous license amendments.
III. Evaporation Addendum
A. In the Evaporation Addendum, including the brief discussion of the "Combination
of Evaporation Capacity with other Waste Minimization Optimizations," the RSE
Team offers a range of proposed evaporation and treatment scenarios, including
elimination of future pond capacity and active (spray) evaporation. These
combinations of optimization strategies have the potential to significantly modify
current and future remedial operating conditions at the HMC site.
B. The RSE Team also offers suggested improvements in the existing treatment
works that could eliminate the need for additional evaporation capacity. Key
improvements suggested include:
• Identifying the basis for significant modifications to optimize performance of
the evaporation/spray/treatment system.
• Substantially reducing or even eliminating the tailings flushing system.
• Considering installation of a subsurface slurry wall around the large tailings
pile.
Unfortunately, the RSE Team's recommendation to eliminate further
consideration of the only source control option available at the site — the
relocation of tailings and subsoil to a prepared site — removes an important, if
not the most important, optimization strategy from further consideration. The RSE
-------
Team should suggest a detailed review of the full range of long-term management
options, including both on-site containment and off-site disposal, in the context of
remediation system optimization.
C. The "Combination of Evaporation Capacity..." analysis appears to conclude that
additional ponds are superfluous if the treatment plant is optimized. The
Evaporation Addendum identifies two approaches: (1) using a second high-
pressure reverse osmosis (RO) line; and (2) routing tailings and toe drain water to
the RO system for treatment. These changes would result in treatment capacity
gains and eliminate the need for additional ponding. These changes would rely on
proven technology, such as the high-pressure RO line, and replicate systems
already on site.
D. Conducting a pilot test, if needed, before incorporation of the two identified
treatment system enhancements, as proposed by the RSE Team, should be
incorporated into existing performance requirements for the NRC license and the
DP-200 NMED ground water discharge permit to supplement and/or optimize the
site's Corrective Action Plan.
E. The "Combination of Evaporation Capacity" analysis does include significantly
expanding the capacity of the RO treatment system as a remediation system
optimization option. The RSE Team should assess whether the RO plant capacity
could be raised to take full advantage of all evaporation pond capacity on site. If
the evaporations ponds can evaporate additional flow, the RSE team should
evaluate combinations that include expanded RO treatment capacity. Expanded
RO treatment capacity could allow for increased extraction of fluids containing
contaminants of concern, particularly if the current system is revised to reduce the
treatment burden associated with flushing flows derived from both injection and
extraction.
F. The discussion of evaporative capacity and treatment options should include a
discussion of the disposition of contaminants of concern that are managed by
those systems, since they are the focus of the remediation effort. The RSE Team
should suggest that the remediation system include identification of the
distribution of radionuclides, metals and gross constituents in fluids and sludges
that are stored in the four existing ponds and in precipitates deposited on and
around the berms of the ponds.
G. The DRSE recommended discontinuance of tailings flushing because it adds
significant volumes of fluids to the system without demonstrating concomitant
progress toward meeting ground water remediation action levels. The Evaporation
Capacity Addendum notes the advantages of reducing wastewater volumes
entering the treatment and evaporation system. Another advantage of ending
flushing that is not recognized in the addendum is that Homestake would no
longer need to keep the top of the Large Tailings Pile (LTP) open to facilitate
operation of injection and collection wells associated with the flushing practice.
-------
Since Homestake has stated previously that 98.6 percent of radon emitted from
the facility is from the LTP and Small Tailings Pile (STP), covering the top of the
LTP with a final radon cover could substantially reduce radon emissions and
resulting radiation exposures to local residents. The final RSE should suggest that
once flushing is terminated, Homestake proceed expeditiously to cover the top of
the LTP. (Installing the final radon cap would not preclude relocating the tailings
if that option is implemented as discussed below.)
IV. Carbon Footprint Addendum
A. The Carbon Footprint Addendum dismisses the tailings removal option based
only on costs and carbon emissions, with no consideration of the long-term
environmental performance goals for the site. This narrow "energy cost only"
view fails to consider long-term objectives for the HMC site — ground water
remediation and reduction of potential health risks for nearby residents. The
addendum appears to provide only a comparison of energy budgets for three
environmental management options at the site, one of which is continuing the
current remediation system, with all of its previously identified shortcomings.
B. The Carbon Footprint Addendum should be incorporated into a section of the
final RSE Report related to long-term environmental management. The RSE
Team should encourage retention and refinement of the tailings relocation option
for analysis beyond its brief and incomplete consideration in the addendum.
C. In the Carbon Footprint Addendum, the RSE Team offers a comparison of
alternatives that are not evaluated using comparable types of information. The
alternatives are: (1) the current system; (2) tailings and subsoil excavation and
off-site disposal; and (3) slurry wall construction. The addendum attempts to
compare and contrast information drawn from the fully engineered and permitted
tailings relocation program for the Moab, Utah, tailings with few site-specific
considerations and the sparsest of conceptual models for the "current system" and
"slurry wall" remediation options.
a. The "current system" as conceptualized by the RSE Team would appear to
be different from the "current system including flushing," which the RSE
Team projects will not meet the goal of attaining NRC-approved "action
levels" for uranium and other contaminants in the alluvial aquifer by 2017.
It should also be noted that the "current system" includes the use of
spraying to enhance evaporation rates, a practice to which the local
community has repeatedly objected, based not only on potential spray
impacts on air and land quality and radiation exposures, but also on their
repeated observations of sprays and spray particulates drifting into the
adjacent communities.
-------
b. The conceptual model for the single "new technology" option, the slurry
wall alternative, may prove valuable, but there is no performance record
applicable to the HMC site or a site of analogous proportions and
conditions. The RSE Team should examine the slurry wall system
installed at the IMC Fertilizer, Inc., Gypsum Stack Expansion in Polk
County, Florida (see: http: //www. ar daman, com/a war d2. htm). This system,
which includes 20,000 linear feet of vertical cutoff walls up to 110 feet
deep, is less than 20 years old and is the only example of currently
implemented slurry wall technology that could be identified online.
Notably, the Carbon Footprint Addendum does not use the IMC slurry
wall system or any other real world example of a slurry wall system, as a
model for comparison and contrast with facilities and hydrologic
conditions at the HMC site.
c. The RSE Report should suggest that EPA, HMC, NRC or NMED gather
data on the full cost of perpetual pump-and-treat systems with and without
slurry walls. This approach would provide for a full-scale comparison of
costs and benefits with the site-specific tailings removal option before that
option is eliminated.
D. A significant portion of the energy and safety costs associated with the tailings
relocation option is associated with the transport of tailings and subsoil to an
alternative site outside of the San Mateo Creek floodplain. Identification of a site,
or sites, closer to the existing tailings facility and thorough consideration of
transportation alternatives (e.g., a slurry pipeline with wastewater recycling,
conveyor-belt systems, or rail transport) may allow costs identified for the tailings
relocation scenario to be significantly reduced.
Truck driver and equipment operator jobs are of fundamental importance to
communities with a history of mining activity. Both are associated with safety
risk, based on miles logged on the equipment. Employment opportunities offered
by tailings removal may represent the largest number of local jobs available in the
uranium industry for many years unless and until a new uranium mill is
constructed to process ore from the hard rock uranium mine proposals in the Mt.
Taylor area.
As a point of comparison, the potential employment opportunities associated with
tailings relocation should be recognized for the substantial personal, corporate and
governmental income it could generate, and for its potential to add value to the
local economy by removing a contaminant source from a floodplain upstream of a
growing community. As it now stands in both the DRSE Report and the addenda,
the relocation option is viewed only as a set of safety risks and carbon emissions,
with no other attributes.
-------
The RSE team offers a set of important but arbitrary assumptions that are heavily
weighted in favor of the unproven pump-and-treat and slurry wall remedies.
Those assumptions allow for a 75-88 percent reduction in additional pump-and-
treat technology and operating costs for a slurry wall over a 50-75 year period, but
do not indicate whether applicable standards will have been met or pre-existing
ground-water quality restored through the use of these remediation
methodologies. The failure to consider full-scale, long-term management costs for
the "current system" and slurry wall alternatives compared with tailings relocation
gives those options an unwarranted advantage that is not supported by the
performance of those technologies.
Long-term management options critical to the remediation of the HMC site need
to be more fully examined for each remediation option, including the assumptions
used in the analyses.
a. The assumptions of the Carbon Footprint Addendum should be modified
to extend the active life of the HMC site's proposed pump-and-treat
system and slurry walls to a reasonably long period, specifically "up to
1,000 years, to the extent reasonably achievable, and, in any case, no less
than 200 years," as required in 10 CFR 40, Appendix A, Criterion 6(l)(i),
the long-term performance standard set out to comply with the Uranium
Mill Tailings Radiation Control Act of 1978, which the U.S. Department
of Energy (DOE) must apply to the HMC site if and when current site
remediation standards are attained and the site is deeded to DOE.
b. The current remedial system at the HMC site has not been shown to be
effective enough to meet projected performance milestones identified by
HMC and regulatory agencies, even after more than 30 years of active
remediation conducted by a site owner with the capacity to modify
pumping, active evaporation and treatment activities. No slurry wall
examples are referred to by the RSE Team to support a major drop-off in
slurry wall costs over a 50-75 year period, much less characterization of
the effectiveness of a slurry wall to meet environmental standards.
c. The DRSE Report attributes a long-term lack of success to the site's
current remediation system, notably the flushing program that the RSE
Team recommends for discontinuance, when compared with attainment of
ground water remediation goals. No effort is made in the Carbon Footprint
Addendum or other portions of the DRSE Report to demonstrate any long-
term performance attributes of a slurry wall system.
d. The lack of success in attaining remediation, including NRC-authorized
"action levels," is reflected in the Concentration Trends spreadsheet
posted to the RSE website by the RSE Team on March 18, 2010, and
discussed, in part, in the previous TASC report, "Observations and
Recommendations Regarding the Draft Focused Review of Specific
-------
Remediation Issues for the Homestake Mining Company (Grants)
Superfund Site, February 2010 - Ground Water Considerations, May 6,
2010." The concentration trends compiled by the RSE Team from HMC
site data show little, if any, reduction in uranium concentrations across
large portions of the site, including (as identified on the tabs of the
Concentration Trends Spreadsheet) the west, north and south sumps, the
NW, ME, SE and SW tails, and wells S2 AND B4. Those locations are
areas not affected by the dilution "plumes" associated with the injection
well systems, which so heavily influence Monitoring Well X, as discussed
in the May 6, 2010 comments on ground water aspects of the DRSE
Report.
G If the RSE Team recognizes the lack of demonstrated long-term success with the
current remedial system and the lack of any demonstration of slurry wall
performance over the long-term, then the tailings relocation option remains the
only remedy that can attain clean-up standards at the site, much less attain clean-
up standards without long-term active monitoring and maintenance. The tailings
relocation option is the only option that offers the possibility of a final remedy for
decontaminating ground water by removing the source of the pollution — the
unlined tailings piles. The current system and slurry wall options are essentially
treatment methods that would operate in perpetuity.
H. Some of the long-term environmental management bonds for New Mexico
facilities include replacement of pumping systems for perpetual pump-and-treat
programs, such as at the Chevron-Questa molybdenum operations. Similar
perpetual treatment costs can be expected if some variation on the current
remedial system or the slurry wall system is eventually used instead of the tailings
relocation option.
I. Retention of the tailings relocation option will allow for cost and performance
estimates for that option to be optimized and will allow for consideration of
appropriately long-term (hundreds to thousands of years) costs and performance
estimates for the other two environmental management scenarios, the current
system and slurry walls, to be assessed at a detailed level incorporating conditions
in and around the HMC site.
J. A new site for permanent disposal of the tailings would have to meet current NRC
and NMED standards, including below-grade disposal in multi-barrier trenches,
placed in a geotechnically suitable location removed from human settlements (see
10 CFR 40, Appendix A, Criteria 1,3,5 and 6, among others). Accordingly, the
tailings relocation option should remain as a primary option for long-term
management of HMC site tailings, unless and until an effective remedy is
demonstrated.
K. Funding the life-cycle cost of remediation at the HMC site has been and will
continue to be a significant public cost. Accordingly, consideration should be
-------
given to use of the site for renewable energy generation to offset carbon costs and
fund remediation and local employment.
V. Need for a Long-Term View of Local and Regional Ground Water Protection
A. The two RSE Report addenda continue to emphasize short-term (50-year or less)
conditions in San Mateo Creek, including the HMC site, rather than longer-term
(100-year and beyond) flow conditions in which historic flows may be restored.
The HMC site does not exist in isolation from the historical surface and ground-
water flow patterns of the watershed around it
B. The historic flows in San Mateo Creek, including, but not limited to, flows from
proposed uranium mine dewatering projects (see the Roca Honda Mine
application:
http://www.emnrd.state.nm.us/MMD/MARP/permits/MK025RN.htm; click on
"Mine Operations Plan") will provide a perpetual source of upstream flow, both
surface and subsurface, into the HMC site without requiring an extensive,
perpetually-endowed pumping effort.
C. The historic flows of Bluewater Creek, retained by the rapidly aging Bluewater
Dam in the Zuni Mountains, are likely to return to the Bluewater Valley
eventually and also provide a perpetual source of upstream flow.
D. Management of environmental management activities on site continues to assume
that the small and large tailings piles in the floodplain of San Mateo Creek near its
confluence with Bluewater Creek will continue to be permitted and maintainable
as permanent disposal sites. These piles are not lined, will take many more years
to dry out before they cease to be sources of fluid infiltration to the alluvium and
underlying Chinle bedrock, and, in the case of the Small Tailings Pile, will be the
final disposal location for solid wastes associated with the current remediation
system.
E. Management of the thousands of acre-feet per year of water that flow through the
area affected by the HMC site tailings continues to evolve. The RSE Team should
consider much longer-term conditions than the 50-year life of HMC in the
Bluewater Valley. The RSE Team, and applicable regulatory programs, should
aim to restore natural ground water and surface water flow conditions without
active maintenance as the appropriate environmental conditions if and when
standards are attained in areas affected by HMC operations. Final conditions
should not rely on deed restrictions and temporary provision of alternative water
supplies.
-------
E2 Inc. Project Manager and Work Assignment Manager
Terrie Boguski, P.E.
913-780-3328
tboguski@e2inc. com
E2 Inc. Work Assignment Manager (beginning July 23, 2010)
Eric Marsh
512-505-8151
emarsh@e2inc. com
Wm. Paul Robinson and Chris Shuey, TASC Subcontractors
Southwest Research and Information Center
P.O. Box 4524, Albuquerque, NMUSA 87196
505-262-1862
sricpaul@earthlink.net, sric.chris@earthlink.net
E2 Inc. Program Manager
Michael Hancox
434-975-6700, ext 2
mhancox@e2inc. com
E2 Inc. Director of Finance and Contracts
Briana Branham
434-975-6700, ext 3
bbranham@e2inc. com
E2 Inc. TASC Quality Control Monitor
Paul Nadeau
603-624-0449
pnadeau@e2inc. com
10
-------
July 23, 2010
Ms. Kathy Yager
U.S. Environmental Protection Agency
Technology Innovation and Field Services Division
11 Technology Drive (ECA/OEME)
North Chelmsford, MA 01863
Dear Ms. Yager,
Bluewater Valley Downstream Alliance (BVDA) submits the following comments on the Army
Corps of Engineers June 18, 2010 Addenda to the Feburary 2010 Draft Remediation System
Evaluation for the Homestake/Barrick Gold Mining Company Superfund Site in Milan, N.M.
1. The Large Tailings Pile restricts a major flood plain. It is unlined and will leak contaminants
in perpetuity.
2. The Large Tailings Pile as well as the other tailings pile and waste from current evaporation
ponds must be removed to a safe, permanent storage site. No other alternative provides a full
remedy, protective of future generations. We hereby request the EPA to extend the USACE's
scope of work to include a serious and full consideration of removal and long-term storage of
the tailings piles and contamination wastes.
3. If Homestake/Barrick's expert is correct and most of our radon exposure comes from the
tailings piles and not the ponds, the tailings piles need interim cover to reduce radon exposure
to our community until they are removed.
4. Clearly, Homestake/Barrick Gold must increase RO capacity to enable a full cleanup of
contaminated groundwater. The RO process must be adequate to eliminate the need for
spraying, which BVDA continues to oppose because it exposes the community to radon and
has never been confined to pond berms as aerial photos and community experience confirm.
5. BVDA assumes and expects that the optimization identified by the RSE process will become
the basis of a more complete review of Homestake/Barrick Gold's Corrective Action Plan by
the NRC under the Atomic Energy Act and the National Environmental Policy Act and that
the NMED will use it in future Discharge Plans under the NMWQA.
6. Time is of the essence. Our community has suffered long enough and it is no longer
sufficient for the NRC to simply allow another five years for cleanup. This has been the
policy for too long and has allowed Homestake/Barrick Gold to evade their responsibility
with inefficiency and delays. New cleanup goals are needed and Homestake/Barrick Gold
must commit the resources to solve this contamination problem.
BVDA hopes and expects there will be further opportunity to comment on the RSE report before it is
finalized and made public. BVDA looks forward to learning soon how the Nuclear Regulatory
Commission and Homestake/Barrick Gold plan to implement RSE recommendations once the report
is finalized.
Sincerely,
Candace Head-Dylla,
for Bluewater Valley Downstream Alliance
#6 Ridgerunner Rd.
Grants, NM 87020
505-401-4349; cuhl48@,psu.edu
-------
cc: Attached list
Congressman Martin Heinrich
20 First Plaza NW, Suite 603
Albuquerque, NM 87102
Congressman Ben R. Lujan
811 St. Michael's Drive Suite 104
Santa Fe, NM 87505
Congressman Harry Teague
Los Lunas Office
3445 Lambros Loop NE
Los Lunas, NM 87031
Senator Jeff Bingaman
625 Silver Avenue, SW, Suite 130
Albuquerque, NM 87102
Senator Tom Udall
Albuquerque Plaza
2013rd St. NW,
Suite 710,
Albuquerque, NM 87102
-------
BILL RICHARDSON
Governor
DIANE DEN1SH
Lieutenant Governor
NEW MEXICO
ENVIRONMENT DEPARTMENT
Ground Water
1190 St. Francis Drive, P. O. Box 5469
Santa Fe»NM
Phone 827-2900 Fax 827-2965
www.nmenv.state.nm.us
RON CURRY
Secretary
SARAH COTTRELL
Deputy Secretary
July 19, 2010
Ms. Kathleen Yager, EPA
U.S. Environmental Protection Agency
Technology Innovation and Field Services Division
11 Technology Drive (ECA/OEME)
North Chelmsford, MA
RE: Review comments on "focused review of remediation issues" (February 2010 draft);
appendix on evaporation pond capacity, and new section 4.4.4 "Removal of tailings"
Dear Kathy:
The New Mexico Environment Department (NMED) herein submits comments on tie new appendices to
the Remedial System Evaluation (RSE) report captioned above.
ggng ...... gi:pgg:i|i
1 . Elements of the "proposed pumping scenario" should be briefly summarized in this appendix for
additional clarity to the reader. From Section 4.1 of the RSE, NMED understands that the primary
element of this scenario is discontinuation of current flushing for the Large Tailings Pile.
2. The projected effluent rate of the toe/taitings drain collection system (65 gpm [Table 5]) under the
proposed pumping scenario inexplicably is indicated to be higher than that of the current pumping
scenario (61 gprn [Table 4]). Although the rate under the proposed pumping scenario might egual
that of the current pumping scenario temporarily, the RSE that the rate from this source
should significantly with time (Section 4.1, p. 19). Therefore the analysis in
Tables 2 through 7 should be reviewed and modified accordingly to account for this projected
decline.
3. The Corps of Engineers' RSE team should consider including an of modified
evaporation or influent under implementation of modifications in
section 5.3, and the consequent on the necessary evaporation capacity.
4.4.4 Removal of Tailings (proposed new RSE
1 . Implementation of a slurry wall, as included in Table 4, would continuation of ground
water extraction in perpetuity; It is unclear what time is modeled in the calculation is
in Table 4.
contact L. Mayerson at (505) 476-3777 or Jerry at {505} 827-0652 if vcu have
any questions.
-------
Ms. Kathleen Yager, EPA
RE: Review comments on "Focused review of specific remediation issues" (February 2010 draft); new
appendix on evaporation pond capacity, and new section 4.4.4 "Removal of tailings*
July 19, 2010
d L Mayergon
Superfund Oversight Section
Jerry Schoeppner
Mining Environmental Compliance Section
Ground Water Quality Bureau
New Mexico Environment Department
copies:
Mr. Sairam Appaji, EPA
HMC 2010 correspondence
NMED/GWQB/SOS July 2010 read file
-------
Homestake Mining Company Comments on Draft Final Report submitted December 9, 2010
Cmt#
Comment from HMC
Response
The flushing program is proactive at accelerating
the removal of uranium mass from the pile,
allowing for its capture and treatment and
preventing the long-term drain down of
continuously elevated concentrations of uranium
over the foreseeable future. Ending this program
is not warranted and would be short-sighted in
the absence of a better approach because it
would prolong the environmental restoration
without any means of controlling the source of
uranium to groundwater.
We understand HMC's position. We acknowledge
that there has been a significant benefit to the
flushing program, and the mass removed from the
pile has been significant. Still, HMC has not
adequately addressed the concern regarding the
certainty in any conclusions based on data from
monitoring points with very long screens. See
response to summary comment 2.
The rebound of uranium into tailings water and
subsequent recontamination of the alluvial
aquifer is in fact being mitigated by the flushing
program. The flushing program is both removing
uranium mass and establishing geochemical
conditions in the LTP that lead to greater stability
with respect to immobilized uranium (e.g.,
lowered ionic strength, moderate pH, and
lowered alkalinity). In addition, the geochemical
conditions that have been created by flushing
may be enhanced through the addition of
amendments to the LTP (e.g., phosphate) that
serve to further immobilize uranium and "blind-
off" any uranium in lower-permeability materials
and prevent back diffusion. A relatively limited
number of these locations may exist and are
currently being evaluated by HMC.
Given that our concern focuses on the likelihood that
much of the fluids have not been flushed, one test
that would confirm or deny this hypothesis is to
conduct a rebound test in part(s) of the pile for some
period of time, as suggested in the Recommendations
of the Draft Final Report. Such rebound testing must
include, in our opinion, new monitoring points with
short well screens.
We support the proposal to test amendments that
would work to further immobilize the uranium,
especially if HMC/Barrick can find an economical way
to implement such an approach.
The recommendation that a pipeline to slurry
tailings to a repository that is 20 miles away be
considered is overly simplistic and the
incomplete analysis that justifies this serves to
weaken the merit of the RSE Report. HMC
believes that this option would be far from
protective of human health and the environment
and is technically infeasible as described.
USAGE does not support movement of the tailings
pile by any means due to the risks to workers and the
community, carbon emissions, and the resource
impacts. The analysis of the carbon emissions for a
slurry transport system was done as a comparison to
trucking the tailings to another location. We agree
that a number of aspects of a slurry transport system
are not specifically included in the analysis or cost
estimate. We agree, too, that there will be an impact
to ground water resources. A clarification of this fact
has been added.
The slurry wall is not feasible as described and
further evaluation shows that factors such as
extreme depth of excavation, inability to create a
competent bedrock key, and inability to assure
continuity of the slurry wall. Each of these
factors taken separately or in combination
seriously discounts this as a technology that
holds merit at the Grants site.
USAGE agrees the slurry wall alternative is not
appropriate for addressing seepage through the
bedrock aquifer, and the slurry wall depths were
estimated based on the depth to top of rock. These
assumptions are documented and were the basis for
the estimates received from a slurry wall contractor.
The contractor indicated that the wall through the
unconsolidated materials is feasible to the assumed
depths. The estimated costs are certainly
approximate. We are not advocating the use of the
slurry wall unless economically justified. If one
-------
hypothesizes a significantly longer duration of
pumping than currently planned (as USAGE does) the
economics of the slurry wall would seem more
favorable. The potential incompatibility between the
tailings liquids and the slurry is a legitimate concern
and a mention about the need to assess the
compatibility has been added to the text.
Comments on previous responses
HMC Comment 25: the ACOE states concurrence
with the comment pointing to the inaccuracy of
the statement that irrigation water is affecting
groundwater through leaching; although the
clarification was not made in the revised
document.
Correction to section 2.1.4 has now been made.
HMC Comment 27: the ACOE indicates that the
CSM figure descriptions will be clarified to better
indicate known sources, however this change
was not made in the revised document. In
addition, requested changes to the CSM were
not made. The mill was not removed as a
primary source, and the drinking water pathway
for groundwater remains complete.
The CSM figure was revised to clearly show that no
known, only potential, release mechanisms existed
for the buried mill debris. This is consistent with the
circumstantial evidence of a source in that area as
described in the response to Comment 4. The
drinking water pathway was reevaluated based on an
NMED comment (Comment 52) and the 2009 Land
Use Review/Survey published by HMC.
HMC Comment 32: the ACOE indicates that
changes will be made to correct the awkward
wording relative to groundwater contamination,
however this change was not made.
Correction to section 4 has now been made as
requested.
HMC Comment 39: the ACOE "noted" HMC's
comment relative to an incorrect citation for a
new immobilization technology; however the
correction was not made in the revised RSE.
Correction to section 4.4.3 has been made.
HMC Comment 40: The ACOE indicates that text
will be modified to correct the discussion of
selenium chemistry, and to correctly indicate
that selenium exists as a cation rather than as an
anion; this correction was not made in the
revised RSE.
The language has been revised to the following:
"Although it is feasible to add an additional ion
exchange column to remove the molybdenum, no ion
exchange resin was found that could reliably remove
selenite (SeO4"2 or HSeO3"), which is one of the
anionic forms of selenium that may be present in the
treatment plant feed. Therefore, this option was
eliminated from further consideration."
-------
Homestake Mining Company's Comments on
the U.S. Army Corps of Engineers' Focused Review of Specific Remediation Issues:
An Addendum to the Remediation System Evaluation for the Homestake Mining
Company (Grants) Superfund Site, New Mexico
(Draft Final Report, August 20, 2010)
December 9, 2010
Homestake Mining Company of California (HMC) respectfully provides the following
comments and concerns relating to the Draft Final Addendum to the Remediation System
Evaluation for the Homestake Mining Company (Grants) Superfund Site, New Mexico prepared
by the Army Corps of Engineers (ACOE) and dated August 20, 2010.1
As a preliminary matter, we recognize that the RSE addresses many of the comments and
concerns raised by HMC in comments submitted by HMC on May 7, 2010 in response to
ACOE's draft circulated in February of 2010. HMC is appreciative of these changes and of the
ACOE's courtesy in providing HMC this opportunity to provide additional comments. However,
the current draft RSE appears to have overlooked, or rejected, many of HMC's primary
concerns.
Rather than repeating each of the points raised in HMC's comments of May 7, 2010, HMC takes
this opportunity to reiterate its most fundamental concerns with the conclusions and
recommendations in the RSE.
HMC's primary concerns can be summarized as follows:
• The RSE's recommendation to end the flushing of the large tailing pile (LTP) is
premature and should be rejected;
• The RSE reflects fundamental misunderstandings regarding the nature of the tailings
material;
• The RSE's suggestion to consider a pipeline to slurry tailings to an engineered repository
is inappropriate and should be removed from the report; and
1 We note that a prior Draft Final Remediation System Evaluation Report dated December 19, 2008 was prepared by
Environmental Quality Management under contract with the United States Environmental Protection Agency
(USEPA). For the sake of simplicity, the August 20, 2010 Draft Final Addendum will be referred to herein as the
"RSE.".
December 9, 2010 Homestake Mining Company Page 1 of 12
-------
• The RSE's continued inclusion of a slurry wall around the LTP as a viable remedial
alternative is ill-advised and should be removed from the report.
1) Flushing of the LTP is effective and must be allowed to continue.
HMC disagrees with the RSE's recommendation to discontinue flushing of the LTP.
Significantly, both the Nuclear Regulatory Commission (NRC) and the New Mexico
Environment Department (NMED), both of which have long histories with the Site, also
disagree with the RSE's recommendation to discontinue flushing.
The flushing program is clearly removing uranium mass from the LTP and remains the best
approach for uranium source treatment in order to meet future, long-term sustainable site
remediation endpoints. The following figure was presented in HMC's comments on the draft
report; additional analysis of this figure shows that the rate of uranium removal and recovery
has significantly increased with the full implementation of the flushing program. This
recovery rate will continue until reaching the point at which the more permeable pore space
has been flushed and uranium concentrations decline.
70
60
Uranium
Concentration
(mg/L) 50
10
Pounds of Uranium Removed
from Tailings Pile
Average Uranium
Concentration in Toe
Drains \
160000
140000
120000
Cumulative
Pounds of
100000 Uranium
20000
1992 1993 1994 1995 19% 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Figure 1. Mass of uranium recovered by the large tailing pile extraction wells and
toe drains and decreasing uranium concentrations; dashed line shows the rate of
uranium removal (7,500 pounds/year) prior to full implementation of the flushing
December 9, 2010
Homestake Mining Company
Page 2 of 12
-------
program; solid line shows the rate of uranium removal (12,000 pounds/year) with
full implementation of the flushing program. Note that the removal rate would
have been higher over the last 4 years if extraction could have proceeded at the
full system capacity design rate through approval of an additional evaporation
pond. This approval was received from NMED in 2010 and the new pond has
been constructed and put into service in early December 2010.
The flushing program has made considerable progress, specifically in those areas of the LTP that
have been the focus of the program (the low permeability slimes; see Figure 2). These locations
are appropriate for an evaluation of the "rebound potential," as suggested by the ACOE (this is
discussed further in the following section).
URANIUM >40 mg/l
URANIUM 30-40 ng/l
URANIUM £0-30 mg/l
URANIUM 10-20 ng/l
URANIUM <10 ng/l
TAILINGS URANIUM (mg/l)
2009
Figure 2. Map of the 2009 uranium concentrations in the pile showing the
significant reduction in concentrations resulting from the flushing and extraction
program. For 2009, approximately 67.5 percent of the west side slime area has
uranium concentrations less than 5.0 mg/L, and 45.5 percent of the same area has
concentrations lower than 2.0 mg/L.
The flushing program has also provided opportune locations for an evaluation of the use of
phosphate to promote the precipitation and retention of uranium within the LTP. A test of this
approach is planned in areas that have achieved moderate ionic strengths, and lowered alkalinity
and uranium concentrations.
December 9, 2010
Homestake Mining Company
Page 3 of 12
-------
The RSE expresses concern that HMC may be overestimating the decrease in uranium
concentrations. Specifically, the RSE contends that heterogeneity of the tailings material has
prevented uniform flushing of the pore fluids. It also contends that because most of the wells
have long screened intervals it is difficult to assess representativeness of the samples recovered
from wells in the LTP. Finally, because flushing performance has recently diverged from the
model prediction, there is concern about the time estimated to achieve flushing performance
goals. HMC has long recognized the heterogeneity of the tailings material and the flushing
program is designed specifically to address this through closely spaced injection and collection
wells in the finest-grained materials (tailing slimes). Preferential flow paths are likely to be
present, however samples recovered from a relatively large number of wells, even with long
screens, provides an accurate snap shot of flushing performance. The restoration curves for
numerous wells show a first step down in reduction in concentrations due to the more permeable
flow paths. We are presently observing the final step in concentration reduction that is due to the
slower slime flow paths. HMC has been evaluating tailing heterogeneity and preferential flow
through depth-specific sampling and tracer tests as part of a program to evaluate alternatives for
groundwater treatment. Divergence between model predictions and flushing performance is due
to limited water management capacity and this will be addressed through operational use of EP-
3. Rather than propose measures to increase confidence in HMC's reported results, however, the
RSE appears to assume that flushing is failing to achieve the desired outcome and therefore
should be discontinued.
HMC does not agree with the recommendation to end the flushing program. The flushing
program has made significant progress in controlling the source of uranium to the alluvial
aquifer, and has effectively moved the remedial system toward meeting remedial end points
sooner rather than delaying this further by allowing uranium to gravity drain from the LTP. In
addition, flushing has achieved the appropriate geochemical conditions in the LTP so that
additional stabilization can be implemented if feasible and appropriate. Ending the flushing
program would set the remedial system back and would stop the significant progress that has
been achieved, as well as removing the capability to optimize remediation over the near term.
2) After flushing is completed, the LTP is unlikely to be a source of soluble uranium.
The ill-advised recommendation in the RSE to discontinue flushing in the LTP appears to be
based on two misconceptions regarding the condition of the fine-grained tailing material in the
LTP after the completion of flushing, namely that: (a) soluble uranium will remain in the LTP,
and (b) insoluble uranium will reoxidize and become more soluble.
a. Soluble uranium will be removed by flushing.
The RSE concludes that, because 2.6 million pounds of uranium will theoretically remain in LTP
after the completion of flushing, flushing will not prevent soluble uranium from migrating from
December 9, 2010 Homestake Mining Company Page 4 of 12
-------
the LTP after flushing is complete. In reaching this conclusion, however, the RSE fails to
differentiate between soluble and insoluble uranium—a critical distinction.
Analyses of the milling process and uranium recovery efficiencies show that the majority of the
labile uranium was recovered from the ore during processing and that the remaining uranium is
present in an insoluble, immobile mineral phase. Soluble uranium in tailings pore water is
present in the LTP because it was originally introduced in soluble form during spigoting of the
slimes onto the pile, not due to further dissolution of the mineral phase material.
Because further partitioning of uranium into a soluble phase will be minimal, the residual
presence of insoluble, immobile mineral phase material in the LTP is irrelevant. This is
supported by an understanding of the milling process, and the use of highly alkaline solutions
applied to crushed ore to effect maximum dissolution of recoverable uranium (see page 8, HMC,
2010). Therefore, the majority of the uranium remaining in the tailings in LTP is associated with
recalcitrant mineral phases.
The RSE also suggests that uranium may diffuse out of the "many pore spaces that contain fluid
that are not significantly participating in the flow if in fine-grained or in dead-end pores." The
concern appears to be that the uranium may diffuse out of these less mobile zones after flushing
is complete. The RSE therefore suggests that a pilot test be conducted to evaluate rebound in
concentrations in a portion of the tailings pile.
In fact, the flushing program is designed to access these low permeability zones with densely
spaced injection and extraction wells and fresh water injection. The injection wells and
extraction (collection) wells are numerous and clustered together so as to provide maximum
flushing effectiveness in the finest grained tailing material (slimes) where flow between the wells
is slowest due to low permeability. The slimes areas are also where dead-end pores will be most
prevalent and are purposely targeted in the flushing strategy. In order to verify the efficacy of
the flushing program, HMC has planned a rebound evaluation as part of ongoing work in the
LTP for the evaluation of alternative groundwater remediation treatment approaches.
b. On-going testing suggests that re-oxidization is unlikely.
The RSE suggests that the flushing of the LTP may have created reducing conditions that reduce
the solubility of the tailings material. The RSE therefore expresses concerns that, when flushing
is discontinued, re-oxidization may occur, resulting in higher solubility of the tailings material.
Although HMC has considered the potential for re-oxidation of the tailings material,
geochemical conditions in the LTP make it unlikely that this will be an issue, specifically
because the bulk of the uranium removal is due to flushing and not due to uranium precipitation
through reductive processes. In addition, introduction of strong oxidants that access the entire
December 9, 2010 Homestake Mining Company Page 5 of 12
-------
LTP tailing pore space would be required in order to result in significant concentrations of
uranium generated through oxidative rebound. The RSE suggests that additional geochemical
parameters be collected in groundwater beneath and downgradient of the LTP and that the role of
reducing conditions in the immobilization of selenium be further evaluated. HMC is evaluating
the geochemical conditions, and the presence of reducing conditions in the LTP, as a component
of the ongoing testing in the LTP.
It is also worth noting that the geochemical conditions enhanced by the flushing program creates
ideal conditions for optimization if additional testing were to suggest that rebound may occur.
For example, flushing has resulted in decreased concentrations of total dissolved solids (TDS)
and moderation of pH (from -11 down to 8 - 9). These geochemical conditions enable
approaches such as the application of chemical amendments (such as phosphate) to be more
effective at binding with, and precipitating, soluble calcium and uranium.
HMC does not believe that the recommendation that tailings flushing be curtailed will lead to a
better strategy for uranium source reduction in the large tailing pile. The flushing program
should continue in order to meet remedial targets. It is also highly unlikely that a significant
amount of uranium will be present in a form capable of dissolution upon conclusion of the
flushing program, and soluble uranium trapped in immobile pores will not lead to significant
rebound.
HMC is in the process of evaluating geochemical conditions in the LTP and the potential for
uranium rebound, as well as means to further stabilize those locations that potentially have
uranium trapped in slimes. HMC strongly disagrees with the RSE's recommendation and
believes that flushing is the most proactive source reduction option currently available and to
achieve the remediation targets in a timely manner. As stated previously, we request that this
recommendation be removed from the final RSE report. If this recommendation is not removed,
EPA should nonetheless reject this recommendation as it will not serve to improve the remedial
system at the site.
3) The RSE's suggestion to consider construction of a pipeline to slurry tailings to an
engineered repository is inappropriate and should be removed.
Section 4.4.4 of the February 2010 Draft RSE Report presented a tailings removal alternative
(excavation, hauling, and disposal) that included relocating the tailings to a disposal cell near the
Grants site. The costs for this alternative were scaled based on per cubic yard estimates from a
cost analysis prepared for the Moab uranium mill tailings where the Department of Energy is
currently relocating tailings. The total cost for relocating the Grants' tailings was estimated to be
2.7 billion dollars and, in light of this cost, the ACOE appropriately concluded that "relocation of
the tailings should not be considered further given the risks to the community and workers and
the greenhouse gas emissions that would be generated during such work".
December 9, 2010 Homestake Mining Company Page 6 of 12
-------
In spite of the ACOE's own conclusion that removing the tailings should not be considered, the
RSE now includes an off-hand discussion of the possibility of transporting the excavated tailings
to an engineered repository approximately 20 miles from the Grants site via a slurry pipeline
rather than by overland hauling of the materials. The RSE does not present an opinion as to
whether this could be a feasible alternative or even whether it should be considered.
The RSE acknowledges that a similar tailing slurry pipeline proposal was made for the Moab site
and that it was not accepted, but nonetheless seems to suggest that such a pipeline should be
considered. It is troubling to HMC that this suggestion was in the report knowing that it has
been previously rejected as impractical at other mill tailings sites.
The cost analysis for the Grants site included scaling costs to those developed for the Moab site
in 2003. This cost analysis is overly simplistic and omits several issues that make slurry
transport of tailings not viable. These issues are discussed below.
• A large flow rate of 2,000 gpm would be required to slurry the tailings with 1,500 gpm
being returned; thus, about 500 gpm of makeup water would be needed. There is no
discussion of how to produce and sustain these flow rates from a water rights perspective.
It is simply assumed that the water would be available. The likely source of water would
be from the San Andreas Aquifer and the large pumping rates may have negative impacts
to surrounding groundwater users. This additional water requirement would therefore put
significant stress on the aquifer system. In addition, re-saturating, mixing and slurrying
the tailings could reverse the improvements in tailings water chemistry that has been
achieved by the flushing program.
• Transport of tailings via a slurry pipeline would result in a larger volume of contaminated
media than what currently exists at the site. The additional water that is needed for tailing
slurry transport, which is initially clean groundwater, would become contaminated. It is
not environmentally desirable for a remedial alternative to increase the overall volume of
contaminated media.
• There is no discussion in the RSE as to how the tailings would be handled at the
repository. For instance, the RSE does not indicate whether tailings would be dewatered
and eventually capped or if the repository would be a wet closure. In either case there are
no costs developed for capping of the repository or treatment of the tailing water during
dewatering. Either of these would incur significant costs that are not accounted for in the
analysis and would require significant additional effort to fully evaluate. Further, the
December 9, 2010 Homestake Mining Company Page 7 of 12
-------
slurry pipeline alternative is estimated to take six years to complete, but there is no
mention of possible treatment of tailing water or drain down water beyond six years.
HMC believes that the current discussion in the RSE of a possible slurry pipeline is inappropriate
and should be removed from the final report. Alternatively, an independent cost analysis should
be prepared that fully accounts for potential costs (instead of one based on loosely analogous
situations of different size and scope) and the RSE should comment on the alternatives'
feasibility and likelihood of success or failure.
4) Replacement of the existing hydraulic barrier with a slurry wall is both impractical
and unlikely to provide greater protection
Section 4.4.1 of the RSE evaluates construction of a slurry wall around the LTP as a possible
remedial alternative and continues to recommend that HMC evaluate the economics of the slurry
wall alternative. As stated in our May 7, 2010 responses, HMC has evaluated the economics and
implementability of a slurry wall and found them to be technically infeasible and cost-prohibitive
remedial options given the difficulty of construction and likelihood of incomplete isolation or
collection of the alluvial groundwater because of the excessive depth of excavations.
However, HMC wishes to emphasize that its objection to a slurry wall is not based solely on
economic considerations. HMC also harbors serious concerns with the difficulty of construction
and ability to achieve remedial performance objectives based on site geologic and hydrogeologic
conditions.
The RSE appears to ignore the specific information provided in our previous responses detailing
why a slurry wall would likely fail at the Grants site. The reasons for this are reiterated below:
• Extreme depth of excavation - A slurry wall would have to reach depths of approximately
140 feet in some locations around the LTP. The projected maximum depth will actually
be much greater if all possible migration pathways are to be cut off. A portion of the
LTP is underlain by a mixing zone of saturated alluvium in contact with the Upper Chinle
aquifer. The Upper Chinle aquifer dips to the east; therefore, if this possible migration
pathway within the Upper Chinle is to be cut off by a slurry wall the depth of the wall
along the eastern side of the LTP would be approximately 200 feet (Figure 2-2, HMC,
2003). A slurry wall would become technically infeasible at this greater depth. We know
of no successfully constructed slurry walls to this depth, nor does the ACOE provide any
information to the contrary.
• Bedrock key - An important aspect of the slurry wall is to extend the wall into the
underlying bedrock (Chinle shale) to cut off groundwater flow. Excavation into bedrock
would be difficult at such depths and may require blasting. It is highly unlikely that that
December 9, 2010 Homestake Mining Company Page 8 of 12
-------
an open trench, or trench filled with slurry, could be maintained while the bedrock is
excavated. Traditional excavation equipment cannot perform the rock removal and an
excavator cannot be used to rip into the bedrock. The use of chisels, hydromills, and
other rock coring equipment may be an option, but the unusually long length of the
proposed slurry wall (13,000 ft) would make it very difficult to ensure that the key is
continuous. At the projected maximum depth of 140 feet (along the western side of the
LTP), it will be difficult to achieve a production rate greater than 5 linear foot of key
trench installed to an average depth of 3 feet per day. The key construction alone would
take more than 7 years to construct at this rate. The time frame required to complete key
construction makes the use of a key impractical; however without a key into the bedrock,
the slurry wall will not be effective. If an area of preferential flow develops along the
interface of the base of the wall and the bedrock, accelerated groundwater flow velocities
could likely cause stability failure within the slurry wall backfill material and loss of
containment. On the eastern side of the LTP, it would require that the key penetrate
through the shale from 6,500 to 6,320 ft amsl just to reach the top of the Upper Chinle
Aquifer, continue through the thickness of the aquifer, and finally into the shale 3 feet for
a key. It is doubtful that any equipment can effectively complete that construction task.
• Slurry wall continuity - The deeper a slurry wall is the more difficult it is to maintain
slurry continuity and thickness. HMC provided guidance on slurry wall construction
from EPA in our previous responses, which states that below about 100 feet the
verticality and thus the continuity of grout barriers are difficult to control or confirm.
The ACOE does not comment on this guidance or provide any examples where slurry
walls have been successfully constructed to the expected depths or lengths that would be
required at the Grants site.
• Incompatibility of groundwater chemistry - The relatively high concentration of
dissolved salts in the groundwater will affect performance of the slurry (bentonite or
other clay-type material). Dissolved salts increase the ionic strength of the groundwater
and this will cause the bentonite to be more permeable due to alterations in the swelling
properties of the clay, as compared to clay behavior in lower ionic strength systems. This
further decreases the certainty that a continuous slurry wall can be achieved at the Grants
site.
Based on the potential technical difficulties in constructing a slurry wall, the projected
construction cost of $14,014,000 in the RSE is likely a gross underestimate. The RSE projection
appears to be based on a typical shallow to moderately deep slurry wall installation, and fails to
account for the complexity of installation, mobilization and cost associated with specialty
equipment needed to reach depths greater than 80 feet. The RSE costs also exclude a remote
December 9, 2010 Homestake Mining Company Page 9 of 12
-------
mixing cost that will be required for a wall of this magnitude, depth, and length, and the remote
geographical location of the site. Slurry wall construction to depths greater than 80 feet typically
requires the use of a crane with a clamshell attachment; and specialized attachments to
construct/key the wall into bedrock. Even with specialized equipment to construct the wall keyed
into bedrock, assuring continuity of the key would be extremely difficult and confirmation of a
continuous key would not be possible.
Perhaps most importantly, there is no reason to believe that a physical slurry wall would be more
effective at preventing groundwater migration than the hydraulic barrier currently in operation.
The existing hydraulic barrier has been effective at controlling the plume. There is no benefit to
groundwater remediation in replacing the currently functional barrier with one that, given all of
the uncertainties and construction challenges, will likely not function properly at all.
The slurry wall alternative is uneconomical, impractical in implementation, and uncertain as to
outcome and therefore should be removed from the final RSE report.
Summary
In summary, HMC fundamentally disagrees with the ACOE's conclusions and recommendations
for the Grants site, as follows:
• The flushing program is proactive at accelerating the removal of uranium mass from the
pile, allowing for its capture and treatment and preventing the long-term drain down of
continuously elevated concentrations of uranium over the foreseeable future. Ending this
program is not warranted and would be short-sighted in the absence of a better approach
because it would prolong the environmental restoration without any means of controlling
the source of uranium to groundwater.
• The rebound of uranium into tailings water and subsequent recontamination of the
alluvial aquifer is in fact being mitigated by the flushing program. The flushing program
is both removing uranium mass and establishing geochemical conditions in the LTP that
lead to greater stability with respect to immobilized uranium (e.g., lowered ionic strength,
moderate pH, and lowered alkalinity). In addition, the geochemical conditions that have
been created by flushing may be enhanced through the addition of amendments to the
LTP (e.g., phosphate) that serve to further immobilize uranium and "blind-off any
uranium in lower-permeability materials and prevent back diffusion. A relatively limited
number of these locations may exist and are currently being evaluated by HMC.
• The recommendation that a pipeline to slurry tailings to a repository that is 20 miles away
be considered is overly simplistic and the incomplete analysis that justifies this serves to
December 9, 2010 Homestake Mining Company Page 10 of 12
-------
weaken the merit of the RSE Report. HMC believes that this option would be far from
protective of human health and the environment and is technically infeasible as
described.
• The slurry wall is not feasible as described and further evaluation shows that factors such
as extreme depth of excavation, inability to create a competent bedrock key, and inability
to assure continuity of the slurry wall. Each of these factors taken separately or in
combination seriously discounts this as a technology that holds merit at the Grants site.
In closing, HMC continues to find the RSE to be inadequate in its appreciation of the complexity
of the Grants site and lacking in its understanding of the conceptual site model and remedial
systems. The changes recommended to the systems, and the suggestions for further evaluation,
are for the most part inconsistent and speculative.
HMC believes that continued flushing of the LTP remains the best remedial alternative for the
Site. Nonetheless, HMC will continue to seek out and implement the most appropriate methods
for addressing the unique challenges posed by the Grants LTP and impacted groundwater. To
this end, HMC will continue to evaluate the system and, as the RSE suggests, seek opportunities
to optimize geochemical conditions to promote precipitation and stabilization of uranium,
selenium, and other elements. HMC is committed to the evaluation of these opportunities for
further source control in the LTP, as well as on-going evaluation of rebound potential.
We trust that these comments have been helpful and hope that the ACOE will revise to the RSE
to appropriately address HMC's concerns.
In the event that the ACOE finalizes the RSE in its current form, we urge EPA, NRC, and
NMED to reject any recommendations in the RSE to discontinue flushing of the LTP or give
additional consideration to uneconomical, impractical, and potentially ineffective alternatives
like slurry pipelines or slurry walls.
In addition, HMC has evaluated the comment response table compiled by the ACOE as an
addendum to the revised draft RSE. The following comments were ignored or have not been
addressed in the revised document even though the response table indicates that they were
addressed:
HMC Comment 25: the ACOE states concurrence with the comment pointing to the inaccuracy
of the statement that irrigation water is affecting groundwater through leaching; although the
clarification was not made in the revised document.
December 9, 2010 Homestake Mining Company Page 11 of 12
-------
HMC Comment 27: the ACOE indicates that the CSM figure descriptions will be clarified to
better indicate known sources, however this change was not made in the revised document. In
addition, requested changes to the CSM were not made. The mill was not removed as a primary
source, and the drinking water pathway for groundwater remains complete.
HMC Comment 32: the ACOE indicates that changes will be made to correct the awkward
wording relative to groundwater contamination, however this change was not made.
HMC Comment 39: the ACOE "noted" HMC's comment relative to an incorrect citation for a
new immobilization technology, however the correction was not made in the revised RSE.
HMC Comment 40: The ACOE indicates that text will be modified to correct the discussion of
selenium chemistry, and to correctly indicate that selenium exists as a cation rather than as an
anion; this correction was not made in the revised RSE.
References
HMC, 2003. Grants Reclamation Project Background Water Quality Evaluation of the Chinle
Aquifers. October 2003.
HMC, 2010. Grants Reclamation Project - Cibola County, NM. Homestake comments on
"Focuse Review of Specific Remediation Issues - An Addendum to the Remediation System
Evaluation for the Homestake Mining Company (Grants) Superfun Site, New Mexico" -
February 2010. Letter from Al Cox, Homestake Mining Company of California to Kathy Yager,
U.S. Environmental Protection Agency, May 7, 2010.
December 9, 2010 Homestake Mining Company Page 12 of 12
------- |