DSHW-2024-004728

2/20/24, 8:31 AM State of Utah Mail - Western Zirconium Fall 2023 Plant Area Monitoring Report Comments
https://mail.google.com/mail/u/0/?ik=390e15a6ba&view=pt&search=all&permthid=thread-a:r-4428683323145964712&simpl=msg-a:r-7556225412853…1/1
Karen Wallner <[e-mail]>
Western Zirconium Fall 2023 Plant Area Monitoring Report Comments
1 message
Karen Wallner <[e-mail]>Tue, Feb 20, 2024 at 8:31 AM
To: "Cannon, Lawrence" <[e-mail]>
Cc: "Kent J Bradford ([e-mail])" <[e-mail]>, "Dodson, Eric"
<[e-mail]>, Paige Walton <[e-mail]>
Hi Lawrence,
The Division has completed its review of the Fall 2023 Plant Area Semi-Annual Monitoring Report, dated January 2023,
for Western Zirconium and is providing the attached comments in response. Please let me know if you have any
questions or concerns.
Thanks,
Karen
--
Karen Wallner, MSPH
Environmental Scientist | Corrective Action Section |
Division of Waste Management and Radiation Control,
Utah Department of Environmental Quality
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Comments - WZ Fall 2023 Plant Area Semi-Annual Monitoring Report.pdf
91K
Comments – Western Zirconium Plant Area Semi-Annual Monitoring
Report – Fall 2023 (dated January 2024)

1. 4.0 Groundwater Quality and 7.3 Background 95% UCL – BG-1. If the number of results
does not allow for calculation of a reliable 95% upper confidence limit (UCL), background
values must still be established. For example, the median may be used as the background
value for datasets with less than four detections. Please discuss how the background
values for these minimally detected analytes will be established and include background
values for these analytes in the report.

2. 4.0 Groundwater Quality and Tables 4 through 6. The Report states that results that
exceeded the higher of the Maximum Contaminant Level/Regional Screening Level
(MCL/RSL) or the background 95% UCL appear in bold font in Tables 4 through 6. As noted
in the December 21, 2023, responses to Division comments on the 2023 Spring Plant Area
Semi-Annual Report, results will be screened to background 95% UCLs, Risk-Based
Screening Levels (RBSLs), MCLs, and Tap Water RSLs. Further, comparison to the higher of
these levels may not allow for early detection of low levels of contamination. A more
conservative approach would be to bold an exceedance of the lower of the four levels.
Revise Tables 4-6 to clearly show all the comparison levels (95% UCL, RBSL, MCL, and
tapwater RSL if appropriate). It is also suggested a color shading be used to show
exceedance of each screening level.

3. 4.2.2 Chromium. The Report states that no wells exceeded the MCL for chromium.
However, Pi-3R had a detected concentration of 7,700 micrograms per liter (µg/L) which
exceeds the total chromium MCL of 100 µg/L. Please revise the narrative to correct this
statement.

4. 4.3 Groundwater – Volatile Organic Compounds. The second paragraph discusses volatile
organic compound (VOC) detections in six wells and MCL exceedances in wells A-10 and A-
16. The Report states cis-1,2-cichloroehthene (cis-1,2-DCE) and trichloroethene (TCE)
exceeded MCLs in well A-10. However, total 1,2-DCE also exceeded the MCL in the A-10
sample. Please revise the text in the second paragraph to include the MCL exceedance for
total 1,2-DCE in the A-10 sample.

5. 6.0 Plume Contours and Sentry Well Assessment – Ammonia. The Report states that
Ammonia was detected at Sentry well A-13 at a concentration of 33 J µg/L and is potentially
associated with residual impacts related to the pond area of the site. The Report further
states that A-13 appears to be separated from the Separations and Chlorinations ammonia
plume. It appears that A-13 does not actually serve as a sentry well for the Separations and
Chlorinations plume due to the detected ammonia concentration.

The Division acknowledges that it is possible the ammonia detected concentration at well
A-13 could be associated with the pond area. Additionally, the planned remediation work at
Area of Concern (AOC ) 15 and Solid Waste Management Unit (SWMU) 18 may potentially
affect the groundwater at this location. Ammonia concentrations at well A-13 should be
monitored for changes and for indications of increasing ammonia concentrations indicating
migration of the Separations and Chlorinations plume.

6. 6.0 Plume Contours and Sentry Well Assessment - Zirconium. The Report states that the
zirconium laboratory method detection limit (MDL) is 2.4 µg/L while the RSL for zirconium is
1.6 µg/L. This is a problem - the MDL is not sufficiently low to detect concentrations at the
RSL. Further, the Report states that zirconium concentrations at Sentry wells Pi-19, L-2, and
A-17 are below laboratory MDL of 2.4 µg/L indicating zirconium impacts are not leaving the
Plant area of the site. Based on this, zirconium analytical results reported as below the
detection limit have considerable uncertainty associated with them as the concentrations
may in fact be above the RSL. Please include a discussion of this issue in the Report and
ensure that the MDL for all monitored constituents is below all applicable screening levels
and project requirements.

7. 7.2 Trend Results. The potential causes for constituent increasing trends are discussed for
some of the constituents in this section, but not sulfate, nickel, ammonia, total-1,2-DCE,
cis-1,2-DCE, and trans-1,2-DCE. Please discuss these increasing trends in terms of
dispersion/diffusion, potentially ongoing releases, or other reasons. Additionally, please
discuss the increasing trends compared to changes in the natural geochemistry of
groundwater in the background well BG-1.

8. 8.0 Findings and Conclusions. The Report states that the pilot test reporting for the
additional pilot testing at Pi-3R was placed on hold due to Utah Division of Water Rights
rejection of the Western Zirconium water right application. The rejection of a water right
application may affect the finalization of the Low pH Area work plan, but the rejection of a
water right application should not affect the preparation of the pilot test report. Please
prepare and submit a report of the additional pilot testing activities, results, and
recommendations within 60 days of the date of these comments.

9. Figure 6: Nitrate-Nitrite Isoconcentration Map. Please label the monitoring wells and
include analytical results on this figure.

10. Please provide the output files for the determination of the 95% UCLs.