HomeMy WebLinkAboutDSHW-2024-005265
Westinghouse Electric Company
Nuclear Fuel
Western Zirconium
10,000 West 900 South
Ogden, Utah 84404-9760
USA
March 14, 2024
Doug Hansen
Utah Divis ion of Waste Management and Radiation Control
195 North 1950 West
P.O. Box 144880
Salt Lake City, Utah 84114-4880
RE: Western Zirconium Remediation Work Plan – Area of Concern (AOC) 15 and Solid Waste
Management Unit (SWMU) 18
UTD092024934
Dear Mr. Hansen:
Western Zirconium (WZ) is pleased to provide these responses to Division comments regarding the
Western Zirconium Remediation Work Plan – AOC 15 and SWMU 18 (Work Plan), dated December 2023.
For ease of review, Division comments have been copied below, with WZ responses below each comment
in blue italicized text.
Comment 1. Section 2.3, Confirming Sampling. The text indicates that confirmation samples will only be
collected for the two risk drivers (radium-226 and zirconium). However, Table 1 of Appendix A presents
the AOC 15 risk summary, which shows the human health drivers for soil corrective action include arsenic,
hexachlorobenzene, lead-210, radium-226, radium-228, thorium-228, thorium-230, and zirconium. The
footnote on Table 1 indicates that radddium-226 and zirconium each contribute around 30% of the total
risk. While the investigation data may show radium-226 and zirconium contributing to 50% or more to the
total risk, Utah Administrative Code (UAC) R315-101-5 requires evaluation of cumulative risk. Cumulative
risk includes risk associated with all potential contaminants of potential concern (COPCs) in the site media.
Further, Section 4 of the Division’s Technical Guide for Risk Assessments (August 2, 2005(Utah.gov))
clearly states that reduction of COPCs may not be conducted through a simple comparison to a screening
level or based on frequency of detection. The confirmation sampling and subsequent confirmation risk
assessment must include all the contaminants listed in Table 1 of Appendix A to include arsenic,
hexachlorobenzene, lead-210, radium-226, radium-228, thorium-228, thorium-230, and zirconium. Also,
revise Table 2, AOC Cleanup Levels, to include appropriate screening levels, for all COPCs.
Response 1: Western Zirconium will update analytical constituent s in Section 2.3 of the Remediation Work
Plan to include arsenic, hexachlorobenzene, lead-210, radium-226, radium-228, thorium-228, thorium-
230, and zirconium. Table 2 of the work plan will also be updated with these analytes. Table 2 will be
updated with EPA Regional Screening Levels (RSLs). A risk assessment work plan will be prepared for UDEQ
review and approval. A human health risk assessment will be conducted on existing data to better
understand current risk levels and to better define excavation volumes and the need for additional
samples. After excavation and prior to placement of fill, a human health risk assessment will be conducted
on confirmation data to confirm we meet acceptable risks levels.
Comment 2. Section 2.3, Confirmation Sampling. This section only indicates that confirmation will be
compared to cleanup levels and regional screening levels. Please clarify the text that a post remedial
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action risk assessment will be conducted to confirm residual levels of contamination are protective of all
identified receptors.
Response 2: A post remedial action risk assessment will be conducted after sampling. A risk assessment
work plan be prepared and submitted to UDEQ for review and approval.
Comment 3. Section 2.3, Confirmation Sampling. This section does not address ecological risk. The
Corrective Measures Study (CMS) in Appendix A indicates that ecological risks were within acceptable risk
levels. However, a demonstration that post corrective measures result in concentration protective of
ecological receptors must also be demonstrated, in accordance with UAC R315-101. In lieu of conducting
a final ecological risk assessment, the Work Plan should clearly discuss that a goal of remedial actions is
to remove available habitat and that an ecological waiver is requested.
Response 3: An ecological waiver will be request ed for AOC-15 in the updated Work Plan.
Comment 4. Section 2.3, Confirmation Sampling. The Work Plan states that confirmation samples will be
collected from locations outlined in the CMS and include five locations. As the above comments discuss
the evaluation of risk, number of sample locations must be adequate to provide the required data for
statistical derivation of a revised exposure point concentration (EPC) for the risk assessment analysis.
Please propose a minimum number of eight sample locations.
Response 4: Western Zirconium will add additional confirmation sampling locations to the R emediation
Work Plan. The need for additional confirmation samples will be evaluated and a minimum of 8
confirmation samples will be added to the Remediation Work Plan.
Comment 5. Section 2.3 and 2.4, Confirmation Sampling and Analytes and Analytical Methods. The Work
Plan references risk-based clean up levels that were developed for the chemicals. These levels were
developed in 2012 and will need to be revised based on current toxicity information.
Response 5: Western Zirconium will update the risk-based clean up levels for AOC-15 and SWMU-
18. A risk assessment work plan will be prepared for UDEQ review that will discuss current toxicity
information .
Comment 6. Section 2.4, Analytes and Analytical Methods. Revised Table 2 to include the laboratory
methods for all COPCs. In addition, please include the method detection limits (MDLs) for each COPC
demonstrating the levels are below the cleanup levels. Note that hexachlorobenzene is best analyzed
using Method 8270 for semi-volatile organics; therefore, trip blanks are not required.
Response 6: Western Zirconium will update Table 2 of the R emediation Work Plan to include methods, and
method detection levels. Hexachlorobenzene will be analyzed by USEPA method 8270.
Comment 7. Section 2.5, Results. The Work Plan states that if concentrations exceed the lowest cleanup
levels, further assessment will be conducted when the facility is decommissioned. In accordance with UAC
R315-101, use of engineering controls, such as the HPED liner and clean fill, may only be used if risks are
within the acceptable risk range. The confirmation data must be evaluated, and a risk assessment
conducted to demonstrate that the residual contamination, prior to implementing the engineering
controls, is protective of both the on-site and construction workers. I f results are within the acceptable
limits (equal to below 1E-04 for cancer risk and equal to or below 1 for noncancer), then any excess risk
may be assessed at decommissioning.
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Further, the Work Plan does not discuss controls that will be used to ensure the corrective actions will be
maintained to ensure protection of human health and ecological risk. For example, discuss inspection,
periodic vegetation removal, etc.
Response 7: Western Zirconium will add an operation and maintenance section to the Remediation Work
Plan to address inspection, erosion of cap material, mowing of vegetation, and spraying of phragmites to
reduce habitat .
A risk assessment work plan will be prepared for UDEQ review to address the post excavation risk
assessment.
Comment 8. Section 2.8, Reporting. Please include the analytical data package in the corrective Measures
Implementation (CMI) Report in addition to the summary of the excavation grading, pipe installation,
results of confirmation sampling, as -built documentation, photographs, and field notes.
Response 8: Western Zirconium will include analytical data packages and data validation report s in the
Corrective Measure Implementation Report.
Comment 9. General. In order to ensure protection of birds protected by the Migratory Bird Treaty Act,
corrective measures should be completed prior to nesting or after fledging (spring to early summer), to
ensure minimum impact to receptors.
Response 9: Western Zirconium will make the necessary changes to the Remediation Work Plan and plans
and specifications to restrict construction activities from March 15 through July 15 to accommodate
nesting and fledging season.
Comment 10. As noted in the CMS for SWMU 18, risk to soil were not evaluated due to the presence of
surface water. It is noted that contamination of surface water was noted. As part of the corrective
measures for SWMU 18, surface water is to be mitigated using measures to prevent or minimize the
daylighting of groundwater. As both the surface water and groundwater have associated contamination,
it is reasonable to assume that the soil that has come into contact with water is likely contaminated. Soil
data are needed to ensure that risk to exposure to soil post corrective measures is within acceptable levels
and protective of both human health and the environment.
Response 10:
SWMU 18 consist of two concrete tanks located in a concrete secondary containment structure.
Groundwater and stormwater do not enter the secondary containment structure of SWMU 18. There is a
small stormwater ditch that conveys storm water to AOC-15 and is located on the northeast corner of the
secondary containment structure. Groundwater historically daylighted into this small stormwater ditch.
Groundwater in this area is present at or below the bottom of this stormwater ditch. Groundwater in this
area will continue to be monitored through the Plant Area and Pond Area monitoring Programs. After
construction, stormwater water may be present in this stormwater ditch during precipitation event and
will flow into SWMU 44 through the future AOC-15 stormwater pipeline. Future interactions between
groundwater and surface water near the northeast corner of SWMU 18 will be eliminated or greatly
reduced after AOC-15 construction is complete.
Three soil sample locations will be added to the work plan from the area outside the secondary
containment structure. One soil sample location will be located near the southern portion of stormwater
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ditch near the northeast border with SWMU-18. Two soil samples will be collected from the slope
embankment above the concrete secondary containment structure near the influent lines to SWMU-18.
An ecological waiver will be request ed for SWMU -18 in the updated Work Plan
Please let me know if you have any additional questions or comments . I can be reached at 801-247-0239.
Thank You,
Eric Dodson
Principal Environmental Engineer
Western Zirconium
CC: Lawrence Cannon, AECOM
Paige Walton, UDEQ
Karen Wallner, UDEQ