DSHW-2024-008012

Kaci Mcneill <[e-mail]>
Fwd: [EXTERNAL] ATI East Shop HHRA, ERA, and Additional Investigation Work
Plan Comments
1 message
Ethan Upton <[e-mail]>Mon, Aug 26, 2024 at 5:38 PM
To: Kaci Mcneill <[e-mail]>
Hi Kaci
Can you upload this email to EQ Docs? It corresponds with UTCA-0065.
Thank you!
---------- Forwarded message ---------
From: Blake Downey <[e-mail]>
Date: Fri, Aug 23, 2024 at 8:29 AM
Subject: RE: [EXTERNAL] ATI East Shop HHRA, ERA, and Additional Investigation Work Plan Comments
To: Ethan Upton <[e-mail]>
Thanks, I will take a look at these soon.

--Blake

From: Ethan Upton <[e-mail]>
Sent: Thursday, August 22, 2024 3:24 PM
To: Blake Downey <[e-mail]>
Subject: [EXTERNAL] ATI East Shop HHRA, ERA, and Addional Invesgaon Work Plan Comments

Hi Blake,

The following are comments regarding the ATI East shop Work Plan submitted on August 14, 2024.

Comments for the ATI East Shop:

1. Section 2, pages 2 and 4. Wasatch indicates that it is their opinion that arsenic concentrations in soil are within
the typical average background concentration range for this area. However, no data or demonstration of this opinion
is provided. Either surrogate background levels for arsenic, site-specific background threshold values (BTVs) that
were derived from a facility located within a six-mile radius of the ATI East Shop (Site), or the default Salt Lake County
BTVs should be used to justify arsenic being representative of background concentrations. It may be helpful to refer
to Section 3.3 of the Division’s Technical Guide to Risk Assessment (TGRA). Revise the Work Plan to provide
defensible lines of evidence with respect to arsenic concentrations in soil.

8/27/24, 12:26 PM State of Utah Mail - Fwd: [EXTERNAL] ATI East Shop HHRA, ERA, and Additional Investigation Work Plan Comments
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2. The following comments pertain to Section 3 which outlines the proposed Human Health Risk Assessment
(HHRA) methodology:

a. The first paragraph of Section three indicates that the result of the risk assessment will be used to
determine if the Site meets the requirements for a No Further Action (NFA) determination. Please note that
because contaminants of potential concern (COPCs) have been identified in the groundwater above the
United States Environmental Protection Agency (USEPA) Maximum Concentration Levels (MCLs) and tap
water Regional Screening Levels (RSLs), the Site does not meet the NFA criteria and subsequently cannot
be closed with an NFA determination. The Division, however, will evaluate the results of the risk assessment
to determine if a corrective action complete with controls may be granted.

b. The Work Plan indicates in the second paragraph of Section 3 that the soil from 0-10 feet below land
surface (ft bls) for a construction worker and an industrial/commercial worker will be evaluated. Please note
that the soil exposure interval for calculating risk to a construction worker exposure interval is 0-10 ft bls while
for the commercial/industrial worker, soil exposure interval of 0-1 ft bls and should be applied. Please update
the Work Plan to clarify the soil exposure intervals that will be evaluated for each receptor.

c. Paragraph 2 of Section 3 indicates that background data are not proposed, as only limited metals were
identified as COPCs and that lines of evidence will be used to support risk associated with metals. It is
advised that a site attribution analysis be conducted for the metals, to determine whether a specific metal
should be retained as a COPC for the risk assessment. Either surrogate background levels, site-specific
BTVs that were derived from a facility located within a six-mile radius of the Site, or the default Salt Lake
County BTVs should be used to justify metals as being representative of background concentrations and
eliminated as a COPC. It may be helpful to refer to Section 3.3 of the Division’s TGRA.

d. The final paragraph of Section 3 discusses the soil to groundwater evaluation of COPCs at the Site
using the least conservative of either the risk-based soil screen levels (SSLs) or the Maximum Contaminant
Level (MCL)-based SSL and applying a dilution attenuation factor (DAF) of 20. Please clarify the Work Plan
that the initial comparison to the SSLs will use the maximum detected concentration and if the SSL is
exceeded, the 95UCL may be used. It may be helpful to refer to Section 8 of the TGRA.

e. The exposure pathways and media that will be evaluated are not discussed in the Work Plan. Further,
it is noted that Equations 1 and 2 only address cumulative exposure to soil. The indoor air pathway is
complete for the industrial/commercial worker, and as such must be evaluated as part of cumulative risk.
Please update the text and Equations 1 and 2 to indicate that cumulative risk of both the soil and indoor air
exposure pathways will be evaluated for the industrial/commercial worker.

f. Section 3 indicates the soil exposure pathway for a construction worker will be evaluated. Based on the
conceptual site model, groundwater appears to range from 3 to 8 ft bls indicating there is potential for
migration of contaminants into a construction/utility trench and exposure to a construction worker at the Site.
Update the Work Plan to discuss whether the vapor intrusion pathway for a construction worker is complete
or if restrictions will be placed on the Site limiting construction worker exposure. Please note that if exposure
to a construction worker is likely in the future, re-evaluation of risk will be required prior to any redevelopment
or construction efforts at the Site. Refer to Section 7.2 of the Division’s TGRA.

3. The following comments pertain to Section 4 of the Work Plan outlining the proposed Ecological Risk
Assessment (ERA) Methodology:

a. An ERA may be performed if preferred. However, an ERA waiver may be granted if environmental
conditions indicate 1) the Site is not a viable habitat, 2) the Site cannot be used by potential ecological
receptors as a habitat, and/or 3) complete or potentially complete exposure pathways do not exist due to
8/27/24, 12:26 PM State of Utah Mail - Fwd: [EXTERNAL] ATI East Shop HHRA, ERA, and Additional Investigation Work Plan Comments
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prevailing conditions or property setting such as facilities that are extensively paved or heavily developed.
Please indicate whether an ERA will be performed or whether the Site meets the requirements for an
ecological waiver. For more information on ecological waivers and descriptions of sites that may qualify for
waivers, please refer to Section 9.1 of the Division's TGRA. A request for a waiver, including appropriate lines
of evidence, may be included in the Work Plan in lieu of the EPA Methodology.

b. The first sentence of Section 4 of the Work Plan indicates that the soil exposure interval for “terrestrial
ecological receptors” is from 0-7 ft bls. However, the soil exposure interval for burrowing receptors is from 0-6
ft bls while the non-burrowing soil interval is from 0-1 ft bls (refer to Table 1 of the Division’s TGRA). If an ERA
is going to be performed, please update the Work Plan accordingly.

c. The second sentence of Section 4 indicates background data will not be applied in the ERA. As metals
tend to drive ERAs, it is advised that either surrogate or Salt Lake County BTVs be used to refine
Constituents of Potential Ecological Concern (COPECs). See Comment 2.c above.

d. The last sentence of Section 4 indicates that if the hazard quotient (HQ) used the no-adverse effect
levels (NOAELs) exceeds a hazard index (HI) of 1, a refined assessment using the lowest-observed adverse
effect levels (LOAELs) will be conducted. Please note that only COPECs which had a receptor specific HQ
greater than one using the maximum detected concentration need to be retained as a COPEC for that
receptor for the refined analysis. Refer to Section 9.3 of the Division’s TGRA.

4. Neither Section 4 nor Section 5 of the Work Plan discusses how the indoor air data will be used in the risk
assessment. For the initial evaluation, the maximum detected air concentration (regardless of location in the building)
should be compared to the RSL industrial indoor air concentration and risk and hazard added to cumulative risks
using Equations 1 and 2. Please modify the Work Plan to discuss how the indoor air data will be incorporated into the
risk assessment evaluating the exposure for an industrial/commercial worker.

5. Section 5 of the Work Plan outlines the proposed additional indoor air sampling. The Division is unaware of an
office space at this Site. Paragraph two appears to be language used to describe a different facility. Please update the
text to indicate where samples will be collected and/or reference Figure 2 for sample locations throughout the
warehouse/manufacturing area.

If you have any questions, please feel free to reach out.

Thank you!

--
8/27/24, 12:26 PM State of Utah Mail - Fwd: [EXTERNAL] ATI East Shop HHRA, ERA, and Additional Investigation Work Plan Comments
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Ethan A. Upton
Environmental Scientist | Corrective Actions Section |
Division of Waste Management and Radiation Control

Office: [phone] | Front Desk: [phone]
wasteandradiation.utah.gov

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Division Director’s position, please submit a written request to the Director, including copies of
documents relevant to your request.

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