DERR-2024-004301

195 North 1950 West
Mailing Address: P.O. Box 144840 Salt Lake City, UT 84114-4840
Telephone [phone] ) 359-8853 [phone]
www.deq.utah.gov
Printed on 100% recycled paper
State of Utah

SPENCER J. COX
Governor

DEIDRE HENDERSON
Lieutenant Governor
Department of
Environmental Quality

Kimberly D. Shelley
Executive Director

DIVISION OF ENVIRONMENTAL
RESPONSE AND REMEDIATION

Brent H. Everett
Director
ERRC-020-24

January 31, 2024

Alison Kuhlman
Monticello Site Manager
U.S. Department of Energy
Office of Legacy Management
2597 Legacy Way
Grand Junction, Colorado 81503

RE: Draft Monticello Site Management Plan, Section 5.0 Annual Update
(FY2023-FY2025)

Dear Ms. Kuhlman:

The Utah Department of Environmental Quality, Division of Environmental Response and
Remediation (DERR) has reviewed the Draft Monticello Site Management Plan, Section 5.0 Annual
Update (FY2023-FY2025) for the Monticello Mill Tailings Site and Monticello Vicinity Properties
site following the response to comments from August 31, 2023. The DERR has no additional
comments and concurs with finalizing the document.

If you have any questions, please contact me at [phone].

Sincerely,

Kelsey Robinson, Project Manager
Division of Environmental Response and Remediation

KR/lg
Department of Energy
Washington, DC 20585
Via email: [e-mail]
Ms. Jessica Duggan, Remedial Project Manager
U.S. Environmental Protection Agency, Region 8
1595 Wynkoop Street, EPR-F
Denver, CO 80202-1129
Via email: [e-mail]
Ms. Kelsey Robinson
Division of Environmental Response and Remediation
State of Utah Department of Environmental Quality
PO Box 144840
Salt Lake City, UT 84114-4840
Subject: U.S. Department of Energy Office of Legacy Management Response to
U.S. Environmental Protection Agency and Utah Department of Environmental Quality
Comments dated August 31, 2023, and titled Re: Draft Monticello Site Management
Plan, Section 5.0 Annual Update (FY2023–FY2025)
Dear Ms. Duggan and Ms. Robinson:
Thank you for the comments from the U.S. Environmental Protection Agency (EPA) and Utah
Department of Environmental Quality (UDEQ) sent on August 31, 2023, in response to the
U.S. Department of Energy (DOE) Office of Legacy Management’s (LM) submittal, Draft
Monticello Site Management Plan, Section 5.0 Annual Update (FY 2023–FY 2025). Please see
LM’s response to the EPA and UDEQ comments below.
Comments
EPA and UDEQ (8/31/2023) Comment 1:
Page 4, Section 5.2.1: Update the information about the MMTS I to include the Errata Sheet.
Add the I recommendations back into Table 5-2, as it was in the 2022 SMP.
LM Response (1/12/24) to EPA and UDEQ Comment 1:
DOE appreciates the identification of the deletion of pertinent information. The document has
been updated. Page 4, Section 5.2.1, was updated to include information about the Monticello
Mill Tailings Site (MMTS) Five-Year Review (I) and the Errata Sheet. The I recommendations
were added back into Table 5-2, as it was in the 2022 Site Management Plan (SMP) as
recommended.
EPA and UDEQ (8/31/2023) Comment 2:
Page 4, Section 5.3: Update the reference to the Long-Term Surveillance and Maintenance Plan
(i.e., Dec 2022).
January 29, 2024
2

LM Response (1/12/24) to EPA and UDEQ Comment 2:
Page 4, Section 5.3 was updated to include the citation “(see LTS&M Plan, December 2022,
Rev. 2)” as recommended.

EPA and UDEQ (8/31/2023) Comment 3:
Page 7, Section 5.3.4, last paragraph: In the 2022 SMP, there was language added about
preparing a feasibility study, documenting the decision in a ROD amendment or ESD, and
incorporating it into the QAPP and LTS&M Plan after a ROD amendment or ESD is issued.
Why was this information removed in the 2023 SMP?

LM Response (1/12/24) to EPA and UDEQ Comment 3:
DOE appreciates the identification of the omission. The information was inadvertently removed
due to internal version control. The document has been updated to include the previous language
about preparing a feasibility study, documenting the decision in a Record of Decision (ROD)
amendment or Explanation of Significant Difference (ESD), and incorporating it into the Quality
Assurance Project Plan (QAPP) and Long-Term Surveillance and Maintenance (LTS&M) Plan
after a ROD amendment or ESD is issued.

EPA and UDEQ (8/31/2023) Comment 4:
Page 8, Section 5.4 and Page 9, Table 5-2: Include the activity and milestone dates from the
remaining Issues and Recommendations identified in both the Monticello Vicinity Properties
(MVP) and Monticello Mill Tailings Site (MMTS) Five-Year Review (FYR). This information was
included in the 2022 SMP but removed in the 2023 SMP. Additionally, update the Feasibility
Study target date to the new target date.

LM Response (1/12/24) to EPA and UDEQ Comment 4:
DOE appreciates the identification of the omission. These activities were originally omitted as
they had been completed and no longer considered “Targets”. The omitted information was
added back into Table 5-2 as it was in the 2022 SMP as recommended. Additional submission
dates have been added in parenthesis for completed items. The Feasibility Study target date has
been updated to the new target date as recommended.

EPA and UDEQ (8/31/2023) Comment 5:
Page 9, Table 5-3: I believe the QAPP is almost complete, please add the QAPP to Table 3 –
Guiding Documents as DOE-LM indicated in the September 2022 Response to Comments on the
2022 SMP.

LM Response (1/12/24) to EPA and UDEQ Comment 5:
DOE agrees with EPA’s and UDEQ’s comment. Table 5-3 has been updated with the QAPP
completion date of “April 2023.”

EPA and UDEQ (8/31/2023) Comment 6:
Page 9, Table 5-3: Provide the most current date for the LTS&M Plan in Table 5-3.
3

LM Response (1/12/24) to EPA and UDEQ Comment 6:
DOE agrees with EPA’s and UDEQ’s comment. Table 5-3 has been updated with the most
current completion date for the LTS&M Plan for the Monticello NPL Sites (see Revision 2,
issued December 2022) as recommended.

Please contact me at [phone] or [e-mail] if you have any questions.
Please send any correspondence to:

U.S. Department of Energy
Office of Legacy Management
2597 Legacy Way
Grand Junction, CO 81503

Sincerely,

Alison Kuhlman
Monticello Site Manager

Enclosure

cc w/enclosure via email:
Ryan Kyle, RSI
John Homer, RSI
Yvonne Deyo, RSI
Gary McKinnon, RSI
Michael Butherus, RSI
Document Determination
ELEM/20/138
ALISON
KUHLMAN
Digitally signed by ALISON
KUHLMAN
Date: 2024.01.29 10:30:38 -07'00'

Project Schedules and Milestones December 2023
Site Management Plan Page 1
5.0 Project Schedules and Milestones (FY 2023–FY 2025)

5.1 Establishing Project Schedules and Milestones

As stated in Section 1.1.2, the Site Management Plan (SMP) establishes the overall plan for
Remedial Actions (RAs) at the Monticello Mill Tailings Site (MMTS) and milestones against
which progress can be measured. The SMP also documents the overall plan for RAs at the
Monticello Vicinity Properties site (MVP), which was deleted from the National Priorities
List (NPL) on February 28, 2000. The MMTS and MVP are also referred to as the Monticello
Projects. The SMP was first prepared in 1995 and was revised annually from 1998 through fiscal
year (FY) 2003. Starting in FY 2004, only Section 5.0 of the SMP, “Project Schedules and
Milestones,” is updated annually to reflect revised schedules agreed to by the U.S. Department of
Energy (DOE), the U.S. Environmental Protection Agency (EPA), and the Utah Department of
Environmental Quality (UDEQ). This update of Section 5.0 of the SMP contains project
schedules and milestones for FY 2023–FY 2025. The stipulated penalty milestones listed in this
section are enforceable milestones unless superseded by revised schedules agreed to by DOE,
EPA, and UDEQ or by amendments to the Federal Facility Agreement (FFA) (DOE 1988b).

5.1.1 FFA Requirements

Section XXX of the FFA, “Enforceability,” states that “All terms and conditions of this
Agreement which relate to interim or final remedial actions, including corresponding timetables,
deadlines, or schedules … shall be enforceable. …” The FFA required DOE to submit a work
plan establishing how DOE would complete the tasks required by the FFA and specific
timetables and a schedule for completing RAs. The FFA Work Plan was completed in May 1989
and established the enforceable timetable for completing primary documents identified in the
FFA and for completing RAs.

The scope of work, timetable, and schedule for RAs presented in the FFA Work Plan were
superseded by the Remedial Design (RD) Work Plan, which was identified as a primary
document and was submitted as a final document in January 1992. The RD Work Plan
established a revised timetable with specific, stipulated penalty milestones. The stipulated
penalty milestones were associated with the submittal of primary design documents that would
be generated as part of the RD and notice of award to subcontractors for RA work.

The timetable in the RD Work Plan was superseded by the timetables established in the 1995
version of the SMP. DOE, EPA, and UDEQ concurrence on the SMP has been the basis for
establishing new enforceable milestones and target dates for all activities extending through the
completion of the Monticello Projects. The SMP is a primary document, and, in accordance with
the FFA, the corresponding timetables, deadlines, and schedules are enforceable.

5.1.2 Enforceable Milestones and Nonenforceable Targets

DOE, with EPA and UDEQ concurrence, has developed a 3-year (fiscal year plus 2 years)
rolling milestone approach for establishing a schedule for completing RAs at the Monticello
NPL sites. Under this approach, schedule dates are designated as either “milestones” or “target
dates.” Milestones and target dates are established in consideration of the Monticello Projects
environmental budget allocation. Milestones are enforceable deadlines established for near-term

December 2023 Project Schedules and Milestones
Page 2 Site Management Plan
activities (fiscal year plus 2 years) for which greater fiscal and technical certainty exists. Target
dates are nonenforceable deadlines, generally for longer-term activities (greater than fiscal year
plus 2 years) and may be converted to milestones annually. Target dates may also be established
in the fiscal year plus 2-year time frame and beyond for completing activities associated with a
stipulated penalty milestone. Each year, after receipt of the Approved Funding Program that
reflects the final congressional appropriation for the current fiscal year, existing milestones are
reviewed and adjusted, if necessary. An additional year of milestones is also established,
adjusting the previous target dates, if necessary.

Enforceable milestones for the Monticello Projects are described in Table 5-1 for those activities
in FY 2023–FY 2025 for which stipulated penalties may be assessed against DOE. Each penalty
date listed in Table 5-1 is defined as the date EPA and UDEQ must receive the respective
document in the form identified in the table. Nonenforceable target dates for the Monticello
Projects are described in Table 5-2. As work on the projects progresses, additional documents
may be submitted. Additional documents will be identified in FFA quarterly reports as it is
determined that they are required.

Under DOE’s rolling milestone approach, DOE, EPA, and UDEQ consider a variety of factors
during the annual review and establishment of milestones and target dates. These include funding
availability; latest information on cost estimates; site priorities identified through consultations
among DOE, EPA, UDEQ, and stakeholders; new or emerging technologies; and other relevant
factors. DOE provides the regulatory agencies and other stakeholders with an opportunity to
assist in developing priorities at the sites. Milestones can be renegotiated if there are insufficient
congressional appropriations. Out-year nonenforceable target dates are established using realistic
assumptions. DOE, EPA, and UDEQ recognize the uncertainties associated with long-term target
dates that lay out DOE’s strategic vision of how it ultimately plans to accomplish projects.

Beginning in September 2004, DOE, EPA, and UDEQ concurrence on updates to Section 5.0 of
the SMP became the basis for establishing new enforceable milestones and nonenforceable
target dates.

EPA and UDEQ agree to meet with DOE annually to renegotiate the milestones and target dates
established in the SMP. The enforceable milestones described in Table 5-1 for activities in
FY 2023–FY 2025 may be modified only as part of this renegotiation or through the existing
procedures of the FFA. EPA and UDEQ reserve the right to initiate any action deemed necessary
to enforce these milestones. DOE, EPA, and UDEQ agree to abide by the existing procedure for
resolving disputes as described in FFA Section XIV, “Resolution of Disputes,” and will make all
reasonable efforts to informally resolve any disputes involving insufficient funding before
invoking formal dispute procedures.

Additionally, Section XII of the FFA (DOE 1988b) establishes procedures to be used by DOE,
EPA, and UDEQ for review, comment, and response to comments on documents established as
secondary or primary documents. Primary documents include those reports that are major,
discrete portions of the Remedial Investigation/Feasibility Study (RI/FS) or RD/RA activities.
Secondary documents include those reports that are discrete portions of the primary documents
and are typically input or feeder documents. DOE is responsible for the preparation of primary
and secondary documents according to established time schedules. DOE must simultaneously
submit the documents to EPA and UDEQ. For both primary and secondary documents, EPA and
UDEQ must provide comments within 60 calendar days unless otherwise agreed to by all parties.

Project Schedules and Milestones December 2023
Site Management Plan Page 3
DOE has 60 calendar days to respond to the comments by simultaneously sending a copy of the
responses to EPA and UDEQ unless otherwise agreed to by all parties. For a draft primary
document, a draft-final primary document incorporating the comments is required, along with the
comment responses. The draft-final primary document will become a final primary document
within 30 days unless dispute resolution is invoked. Historically, on Monticello Projects,
additional comments have been received by DOE from EPA and UDEQ during the final review
period and have been addressed by DOE in the submittal of a final primary document.

5.2 Site Status

RAs at the Monticello NPL sites have been implemented in accordance with the Record of
Decision (ROD) for the corresponding site and operable unit (OU):
 ROD for MVP, all OUs: Monticello Vicinity Properties Project, Declaration for the Record
of Decision and Record of Decision Summary, November 1989 (MVP ROD). RAs under
this ROD are complete.
 ROD for MMTS, OUs I and II: Monticello Mill Tailings Site, Declaration for the Record of
Decision and Record of Decision Summary, August 1990 (MMTS ROD). RAs under this
ROD are complete.
 ROD for MMTS, OU III: Record of Decision for the Monticello Mill Tailings (USDOE) Site
Operable Unit III, Surface Water and Ground Water, Monticello, Utah, May 2004. RAs
under this ROD are ongoing.
The remedy selected in the MMTS OU III ROD was modified in March 2009 by a
contingency remedy implemented in the Explanation of Significant Difference for the
Monticello Mill Tailings (USDOE) Site Operable Unit III, Surface Water and Ground
Water, Monticello, Utah (Explanation of Significant Difference [ESD]). As of January 2015,
the contingency includes an expanded pump-and-treat remediation system in a focused area
of the aquifer called the Area of Attainment (AOA) (see Section 5.3.4).

5.2.1 CERCLA Five-Year Reviews

The RAs at the MMTS and MVP do not allow for unlimited use and unrestricted exposure in all
areas because (1) contaminated soil, sediment, and debris removed from the MMTS and MVP
remain encapsulated in the onsite DOE repository; (2) contamination remains in soil at the
MMTS and MVP where supplemental standards were applied; and (3) contamination remains in
MMTS OU III groundwater and surface water. Under the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA), Section 121(c), these circumstances
obligate DOE to conduct Five-Year Reviews (FYRs) of the sites to ensure that the ROD-specified
remedies remain protective of human health and the environment.

The 2022 FYR for the MVP concluded that the remedy at OU H is protective of human health
and the environment in the short-term. In order for the OU H remedy to be protective in the
long-term, DOE will need to implement the three recommendations identified in the MVP FYR
report. DOE received the letter of concurrence from EPA on the short-term protectiveness
determination for the MVP on June 28, 2022; the statutory due date for the MVP FYR report was
June 30, 2022.

December 2023 Project Schedules and Milestones
Page 4 Site Management Plan
The statutory due date for the MMTS FYR report was June 20, 2022; however, revisions to
the MMTS FYR report are ongoing. The initial protectiveness determination for OU I, OU II,
and OU III was short-term protective with the same three recommendations identified for the
MMTS as for the MVP. Following subsequent review and discussion, EPA and UDEQ agreed
with the short-term protectiveness determination for OU I and OU II, but deferred the
protectiveness determination for OU III, stating that additional information was required.
On June 17, 2022, EPA issued a letter of independent finding to DOE that identified a
“protectiveness deferred” determination for OU III. The letter included three additional
recommendations to be implemented by DOE that would provide the information necessary
for EPA to make a protectiveness determination for the MMTS in an FYR addendum. DOE
committed to issuing the final MMTS FYR report by July 29, 2022, and DOE committed to
include as much additional information in the report as could be obtained by that deadline.
Recommendations that will take more time to implement will be completed on the schedule
agreed to in the final MMTS FYR report.

Additional EPA comments on the MMTS FYR report were received on September 9, 2022.
Comments included the need for additional discussion regarding a protective uranium
benchmark for aquatic receptors in surface water. DOE, EPA, and UDEQ subsequently met on
October 19, 2022, and agreed on a path forward for addressing outstanding issues to finalize the
MMTS FYR report. The errata sheets were resolved and submitted on May 31, 2023, and
included the following change(s):

(1) A revised Appendix G that includes DOE responses to EPA comments on the final
FYR report that include additional comments received in September 2022

(2) Revisions to Appendix F that address EPA comments received in September 2022

FYR recommendations that are in process or recently finalized include the following:
 DOE updated the Uniform Federal Policy Quality Assurance Project Plan, also called the
QAPP; Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy
Management Sites (LMS/PRO/S04351), also called the SAP; program directive
PD-2021-10-MNT, “Discharge measurements in Montezuma Creek”; and the reporting
requirements regarding the monitoring well network in the Long-Term Surveillance and
Maintenance Plan for the Monticello NPL Sites (LMS/MNT/S00387), also called the
LTS&M Plan (December 2022, Rev. 2).
 DOE to complete a feasibility study to evaluate remedial alternatives for achieving the
water-quality restoration Remedial Action Objective (RAO).
 DOE to evaluate risk to aquatic organisms using current State of Utah water quality
standards.
 DOE to evaluate whether institutional controls (ICs) are required to prevent human
consumption of surface water for a domestic drinking water source.

5.3 Long-Term Surveillance and Maintenance

In addition to FYRs required under CERCLA, DOE conducts routine inspections and
surveillances (weekly, monthly, and quarterly) and annual site inspections as an ongoing
evaluation of remedy effectiveness. These activities are directed under the DOE LTS&M
program initiated in October 2001. DOE’s Office of Legacy Management (LM) implements

Project Schedules and Milestones December 2023
Site Management Plan Page 5
the LTS&M program. The LTS&M Plan for the Monticello NPL sites is designated as a
“primary” document in the FFA. LTS&M activities at the Monticello NPL sites consist of
periodic surveillance and inspection of supplemental standards properties, monitoring of
earthwork in city streets and utility corridors, management of recovered radioactive material
in the Temporary Storage Facility (TSF) at the onsite repository, operation and maintenance
of the onsite repository, monitoring for compliance with ICs that restrict land and water use,
monitoring groundwater and surface water, and pertinent documentation and reporting
(see LTS&M Plan, December 2022, Rev. 2). DOE plans to schedule quarterly meetings to track
progress of all site activities.

5.3.1 Mill Site Remediation and Restoration

Soil contamination removal activities concluded at the former mill site in July 1999. DOE
transferred ownership of the former mill site property and several adjacent properties (known as
“peripheral properties”) to the City of Monticello in June 2000. Mill site restoration activities
were completed in August 2001. The associated wetland areas (Wetlands 1–3) were fully
restored by 2004. As a condition of the land transfer agreement, the city maintains the transferred
properties for public recreation. DOE continues to monitor the properties for compliance with
ICs that restrict land and water use and to ensure that the remedy remains protective. There are
currently no violations of land or water use restrictions. The former mill site property, which is
part of MMTS OU I, is partially underlain by contaminated groundwater (OU III) and so cannot
be deleted from the NPL at this time.

5.3.2 Repository and Pond 4

Operation of the OU III Groundwater Remedy Optimization (GRO) system began in
January 2015 with groundwater from the AOA pumped to Pond 4, which resulted in increased
water collection in the Pond 4 Leachate Collection and Removal System (LCRS) and the
Pond 4 Leachate Detection System (LDS). LCRS and LDS action-level leakage rates, approved
by EPA and UDEQ, were formally developed in the Repository and Pond 4 Groundwater
Contingency Plan (DOE 1998d in the LTS&M Plan) and are also found in Section D5.0 of the
LTS&M Plan. The action-level leakage rate established for the Pond 4 LCRS is 851 gallons per
acre per day (gpad) (2000 gallons per day [gpd]) and for the LDS is 20 gpad (47 gpd), which is
established over a 7-day period. These action-level leakage rates are based on the area of the
floor of Pond 4, which is 2.35 acres. The leakage rate into the LCRS exceeded its action level
during the week of May 18, 2015, with notification to LM, EPA, and UDEQ of the exceedance
on May 22, 2015. The leakage rate into the LDS also exceeded its action level, and notification
to LM, EPA, and UDEQ was also sent on May 22, 2015. The leakage rate frequently exceeded
the LCRS action level from the week of May 18, 2015, until the week of September 9, 2019,
when the leakage rate fell below the action level. Since the week of September 9, 2019, the
LCRS action level has been exceeded three times, during the weeks of January 24, 2022,
January 31, 2022, and February 7, 2022. The leakage rate in the Pond 4 LDS system exceeded
the action level during the weeks of June 1, 2015 (55 gpd), March 2, 2020 (41 gpd), and
June 15, 2020 (13 gpd), which was caused by equipment failure. As documented in the
LTS&M Plan, the plan for managing these exceedances is to recirculate the LCRS and LDS
leakage back into Pond 4. Currently, the LCRS and LDS monitoring and pumping systems are
functioning as designed to recirculate water back into Pond 4.

December 2023 Project Schedules and Milestones
Page 6 Site Management Plan
5.3.3 Monticello Mill Tailings Site OU IIPeripheral Properties

Completion reports, RA reports, and closeout documentation have been completed for the
remediation of contaminated soil and sediment on all OU II properties. Twenty-two of the
original 34 OU II properties without contaminated surface water or groundwater were deleted
from the NPL on October 14, 2003. Twelve of the OU II properties that are underlain by
contaminated groundwater have not been deleted from the NPL. DOE performs long-term
surveillance of the OU II properties for compliance with ICs that restrict land and groundwater
use and to ensure that the implemented remedies remain protective. There have been no
violations of land or groundwater use restrictions. MMTS OU II properties that have been
remediated for soil and sediment contamination but are underlain by contaminated groundwater
are not eligible for deletion from the NPL until water quality RAOs are achieved.

5.3.4 Monticello Mill Tailings Site OU III—Surface Water and Groundwater

The remedy for MMTS OU III was selected and documented in the MMTS OU III ROD,
signed on June 2, 2004. The MMTS OU III ROD was prepared following the submittal of the
Monticello Mill Tailings Site Operable Unit III Remedial Investigation Addendum/Focused
Feasibility Study, January 2004, as a basis for OU III remedy selection. That document updated
human health and ecological risk assessments and the groundwater model from the 1998
CERCLA RI. MMTS OU III has not been deleted from the NPL because water quality RAOs
have not been achieved.

The selected remedy consists of monitored natural attenuation, ICs, and biomonitoring to
evaluate the potential impacts of selenium concentrations on ecological receptors at specific
locations. Biomonitoring was completed in 2012, in concurrence with EPA and UDEQ, and as
documented in the MMTS 2012 CERCLA FYR.

Analysis of groundwater monitoring data indicates that water quality restoration is not
achievable under the performance metrics established in the ROD. This was first reported in the
2006 annual groundwater report and later confirmed in Monticello Mill Tailings Site Operable
Unit III Analysis of Uranium Trends in Ground Water, August 2007. DOE, with concurrence
from EPA and UDEQ, therefore implemented a contingency remedy for OU III as a requirement
of the ROD. The decision to implement a contingency remedy and the scope of the contingency
remedy were documented in the March 2009 ESD.

The ESD was provided for public review in December 2008 and became effective in
March 2009. In accordance with the ESD, DOE committed to implement groundwater
pump-and-treat remediation as a component of the contingency remedy until RAOs were met
or another remedy was selected. The initial phase of the contingency remedy consisted of
continued operation of an existing ex situ treatment system that was constructed in 2005 as a
technology demonstration project. The ESD also adopted the State of Utah protection standard
for uranium in domestic-use surface water (30 picocuries per liter).

To evaluate the effectiveness of the contingency remedy, DOE, in accordance with the
March 2009 ESD, prepared the Monticello Mill Tailings Site Operable Unit III Water Quality
Compliance Strategy, December 2009. That strategy describes the work elements, schedule, and
data-use objectives of the contingency remedy tasks and presents a conceptual, phased approach
to attain compliance goals. Results and discussion of the completed activities were documented

Project Schedules and Milestones December 2023
Site Management Plan Page 7
in the Monticello Mill Tailings Site Operable Unit III Annual Groundwater Report May 2011
Through April 2012.

During July and August 2013, DOE decided to optimize the contingency remedy by
implementing a more aggressive groundwater extraction and treatment approach. In FY 2014,
DOE prepared an RD/RA Work Plan for the OU III contingency remedy optimization, which
was finalized and approved by EPA and UDEQ in June 2014. As explained in the RD/RA Work
Plan, the objective of the GRO system is to achieve the remediation goal for uranium in the
AOA, which is the portion of the aquifer with the highest uranium. The GRO system consists of
eight vertical extraction wells that pump groundwater from the AOA to a control or transfer
building from where it is batch pumped to an engineered solar evaporation pond. Sixteen new
monitoring wells were installed to monitor restoration progress in the AOA. An additional
six new monitoring wells were installed on the north side of Montezuma Creek in June 2017.

Construction of the optimization system occurred during spring 2014 through December 2014.
Full system startup began in January 2015. The Remedial Action Completion Report for OU III
Groundwater Contingency Remedy Optimization System was submitted to the regulatory
agencies in May 2016 to document the as-built configuration and operating parameters of the
system. Consumptive use of the aquifer water is allowable under an existing state Department of
Natural Resources Fixed-Time Water Appropriation (Water Right Number 09-2347).

As of April 2018, water quality monitoring to assess the performance of the OU III remedy
is conducted in accordance with the SAP and the LTS&M Plan. These documents supersede the
MMTS OU III ROD and the Monticello Mill Tailings Site Operable Unit III Post-Record of
Decision Monitoring Plan, Draft Final, August 2004. The site-specific QAPP for MMTS OUIII
was formatted in the Uniform Federal Policy format and was submitted to EPA and UDEQ in
September 2023.

Operation of the OU III groundwater contingency remedy will continue until current RAOs are
achieved or until it is determined that meeting RAOs under the contingency remedy is not
feasible in a reasonable time. Because recent evaluations indicate that the contingency remedy
may not achieve RAOs in the anticipated time frame, LM is currently preparing a feasibility
study to evaluate remedial alternatives for OU III. A ROD Amendment or ESD will be required
to implement the remedy recommended in the feasibility study. Any determination for
discontinuing the groundwater contingency remedy because RAOs are not met in a reasonable
time frame will require approval from LM, EPA, and UDEQ. Transitioning from the contingency
remedy will also require concurrence on performance monitoring metrics for the new remedy.
The performance monitoring metrics will be incorporated into the QAPP and LTS&M plan after
a ROD Amendment or ESD is issued.

5.3.5 MMTS Long-Term Decommissioning Activities

Components of the MMTS infrastructure that require eventual decommissioning are the
(1) OU III groundwater remediation systems, including the permeable reactive barrier
(PRB); (2) OU III monitoring wells; (3) Pond 4 (repository leachate evaporation pond); and
(4) the water diversion flap of the lysimeter embedded in the repository. This section further
describes decommissioning of these components.

December 2023 Project Schedules and Milestones
Page 8 Site Management Plan
Plans to decommission the PRB are not yet necessary because it is functioning as a groundwater
containment device under the RD/RA Work Plan and the ESD. Upon a decision to remove or
replace the PRB, a decommissioning plan will be documented in an RD/RA Work Plan that will
be subject to EPA and UDEQ concurrence. The PRB is not currently in consideration for
near-term (within 5 years) decommissioning, and an out-year (more than 5 years) date has not
been determined.

The ex situ groundwater treatment system was taken out of service in December 2014. The
decision on whether to remove the ex situ treatment system has not been made, but it is possible
that this system could be decommissioned within the near-term (within 5 years). Upon a
decision to remove the ex situ groundwater treatment system, a decommissioning plan will be
documented in an RD/RA Work Plan that will be subject to EPA and UDEQ concurrence.

Groundwater monitoring for OU III will be conducted until water quality restoration has
attained acceptable levels established by DOE, EPA, and UDEQ. Monitoring wells will be
decommissioned when RAOs are achieved. Monitoring well decommissioning may occur in
phases as regions of the aquifer achieve RAOs. Well decommissioning will be conducted in
agreement between DOE, EPA, and UDEQ. Well abandonment will conform to the substantive
requirements of the Utah well drilling standards, consistent with the OU III ROD.

Decommissioning Pond 4 is contingent on the rate of leachate production from the disposal
cell and the duration of evaporative treatment of OU III contaminated groundwater from the
GRO system. Pond 4 is eligible for decommissioning only if the repository leachate is managed
by other means and when evaporative treatment of OU III contaminated groundwater ceases.
Pond 4 is not currently in consideration for near-term (within 5 years) decommissioning, and an
out-year (more than 5 years) date has not been determined.

DOE continues to monitor the drainage lysimeter embedded in the 7.5-acre facet comprising the
northeast corner of the repository cover. The repository is capped by a vegetated water balance
cover that is underlain by a cell meeting the EPA minimum technology requirements for a
Resource Conservation and Recovery Act Subtitle C cell. The lysimeter is monitored and
maintained through the LM Applied Studies and Technology program. The two existing
lysimeter instrumentation basins were removed and two new upgraded basins were installed in
May 2017.

5.3.6 Monticello Vicinity Properties

Remediation of the MVP was completed on September 30, 1999. The final rule to delete the
MVP from the NPL became effective on February 28, 2000. DOE continues to perform LTS&M
activities for certain vicinity properties through annual inspections, enforcement of ICs, and
monitoring. The affected MVP are the city streets, utility corridors, and U.S. Highways 191 and
491 in Monticello and private property MS-00176, where contamination was left in place and
supplemental standards were applied.

As part of planned utility upgrades and unplanned repairs, radioactively contaminated soils that
are removed from excavations are transported to the TSF at the Monticello repository, with the
exception of material excavated by the Utah Department of Transportation, which has the option
to return radioactively contaminated soils to its excavations in Highways 191 and 491 within
the city limits. DOE provides the required monitoring and radiological controls during these

Project Schedules and Milestones December 2023
Site Management Plan Page 9
activities. Radioactive material stored in the TSF is transported to DOE’s Grand Junction,
Colorado, Disposal Site for permanent disposal. As of June 2023, approximately 6 cubic yards of
radiological soil is stored in the TSF.

5.4 Milestones and Targets

Enforceable milestones applicable to the MVP and MMTS for the current milestone period of
FY 2023–FY 2025 are listed in Table 5-1. Table 5-2 lists pending activities and documents with
associated target dates. Table 5-3 and Table 5-4 list current guiding documents in effect. DOE
can prepare program directives (Table 5-4) to guide field and procedural activities that are
beyond the routine work scope for OU III, as defined in the LTS&M Plan. Program directives
periodically expire and are reissued as necessary. Two program directives expired in 2021:
“Surface-Water Discharge Measurement Protocol” and MNT-2018-02, “Sampling of Permeable
Reactive Barrier (PRB) Wells, LM Monticello, Utah, Disposal and Processing Sites.” The former
was updated and reissued as PD-2021-10-MNT, “Discharge measurements in Montezuma
Creek”; the latter was discontinued because it was determined that PRB wells could be sampled
adequately following protocols described in the SAP without the specialized procedures for
low-yield, high-turbidity wells that were described in the program directive.

Table 5-1. Penalty Milestones in FY 2023–FY 2025

Milestones Stipulated Penalty Datesa
FY 2023 revision of Section 5.0 of Site Management Plan (draft)b August 1, 2023
FY 2024 revision of Section 5.0 of Site Management Plan (draft)b August 1, 2024
FY 2025 revision of Section 5.0 of Site Management Plan (draft)b August 1, 2025
2023 Annual Site Inspection Reportc December 31, 2023
2024 Annual Site Inspection Reportc December 31, 2024
2025 Annual Site Inspection Reportc December 30, 2025
Notes:
a The date EPA and UDEQ must receive the document for review and comment.
b Report progression will be as follows:
 The draft report will be reviewed by EPA and UDEQ.
 Any comments from the draft will be addressed in a final report. If no comments are received on the
draft, DOE will reissue the report as final.
 EPA and UDEQ will issue an acceptance letter of the final report.
c This report is reviewed by EPA and UDEQ but is not part of the concurrence process. The dates shown are for
completion of the final report.

December 2023 Project Schedules and Milestones
Page 10 Site Management Plan
Table 5-2. MMTS and MVP Targets

Activity/Document Purpose Target Date/Scope
Annual groundwater reporta Evaluate water quality restoration progress October of each year
Feasibility Studyb Evaluate remedial alternatives for achieving the
water quality restoration RAOs for OU III Summer 2024
Semiannual FFA meeting Review project status, goals, and schedule Spring and fall of each year
FFA quarterly reportsa Summarize project scope, status, and schedule 15th of February, May, August,
and November of each year
QAPPb Update the QAPP per federal requirements Spring of each year
Performance
Monitoring Metricsb
Develops actions for monitoring the OU III
aquifer after major changes: GRO termination
or PRB removal
Winter 2024
(Develop draft and submit for
regulator review)
Technical document to
Terminate Groundwater
Remedy Optimization
Operationsb
Develops the criteria required for turning off
the GRO system
Winter 2024
(Respond to regulator comments
on draft)
2022 Five-Year- Review Activitiesc
Operable Unit Activity Milestone Date
These activities apply to
MMTS OU I, OU II, OU III,
and MVP OU H
DOE to confirm human health risk evaluation
using EPA PRG calculator
July 31, 2022
(Submitted on July 29, 2022)
DOE to create and send an informational letter
to landowners with deed restrictions that clearly
explains restrictions on their property
December 31, 2022
(Submitted on December 19, 2022)
DOE to complete a vulnerability and
resilience assessment for Monticello sites by
September 2022, provide the assessment to
EPA and UDEQ, and schedule a meeting to
discuss findings
December 31, 2025
These activities apply to
MMTS OU III
DOE to update the QAPP, SAP, program
directive PD-2021-10-MNT, and the LTS&M
Plan to be consistent regarding monitoring
well network
December 31, 2022
(Submitted on April 5, 2023)
DOE to complete a feasibility study to evaluate
remedial alternatives for achieving the water
quality restoration RAO
June 30, 2024
DOE to evaluate risk to aquatic organisms using
current Utah water quality standards
May 31, 2023
(Submitted on December 31, 2023,
comment resolution ongoing)
DOE to evaluate risk to human health and
environment using current Utah water quality
standards
May 31, 2023
(Submitted on December 31, 2023,
comment resolution ongoing)
DOE to evaluate whether ICs are required to
prevent human consumption of surface water
for a domestic drinking water source
May 31, 2023
(Submitted on December 31, 2023,
comment resolution ongoing)
Notes:
a This report is reviewed by EPA and UDEQ but is not part of the concurrence process.
b Report progression will be as follows:
 The draft report will be reviewed by EPA and UDEQ.
 Any comments from the draft will be addressed in a final report. If no comments are received on the draft, DOE
will reissue the report as final.
 EPA and UDEQ will issue an acceptance letter of the final report.
c Excerpts from the Sixth Five-Year Review Report for Monticello Radioactively Contaminated Properties Superfund
Site, San Juan County, Monticello, Utah (June 2022) and the Sixth Five-Year Review Report for Monticello Mill
Tailings (USDOE) Site, San Juan County, Monticello, Utah (July 2022).
Abbreviation: PRG = preliminary remediation goal
Table 5-3. OU III Guiding Documents

Project Schedules and Milestones December 2023
Site Management Plan Page 11
Document Completed
RI Addendum/Focused FS
RI Addendum/Focused FS January 2004
Surface Water/Groundwater Decision Documents
MMTS OU III ROD June 2, 2004
ESDa March 2009
MMTS OU III Water Quality Compliance Strategy December 2009
LTS&M and Monitoring
MMTS OU III Analysis of Uranium Trends in Groundwater August 16, 2007
Sampling and Analysis Plan for U.S. Department of Energy Office of
Legacy Management Sites Revised to include MMTS, January 2016
LTS&M Plan for the Monticello NPL Sites Revision 2 issued December 2022
Quality Assurance Project Plan, Monticello, Utah, Disposal and
Processing Sites April 2023
CERCLA Reviews
Sixth FYR Reports for MMTS and MVP July 2022
Note:
a Explanation of Significant Difference for the Monticello Mill Tailings (USDOE) Site Operable Unit III, Surface Water
and Ground Water, Monticello, Utah.

Table 5-4. MMTS OU III Program Directives in Effect

PD-2021-10-MNT Discharge measurements in Montezuma Creek