DSHW-2024-009483

From: Jasin Olsen <[e-mail]>
Date: Tue, Dec 3, 2024 at 1:42 PM
Subject: Comments to Response to Ecological and Risk Assessment Water Well 9549
To: Erickson, Tyson B CIV USARMY JMC (USA) <[e-mail]>
Cc: Paige Walton <[e-mail]>, Ethan Upton <[e-mail]>
Tyson,
Please find attached comments to the Response to Ecological and Risk Assessment Water Well 9549. Please let us know if
you have any questions.
Thanks,
Jasin
12/6/24, 12:51 PM Fwd: Comments to Response to Ecological and Risk Assessment Water Well 9549 - [e-mail] - State of Utah Mail
https://mail.google.com/mail/u/0/?tab=rm&ogbl#inbox/FMfcgzQXKWjgKbBCnPWrRDjXwHjPJkFC 1/1
Comments for Response to Ecological and Risk Assessment Water Supply Well WIN 9549,
Tooele Army Depot North Area (TEAD-N), November 4, 2024
A screening level ecological risk assessment and human health risk assessment were performed
to evaluate potential impacts to an aquatic community organisms and an outdoor worker from
constituents of potential ecological concern (COPECs) identified in groundwater from water
supply well WIN 9549. The groundwater is pumped into a retention basin and then used as dust
suppressant across the Site. 1,2-dichloroethane, carbon tetrachloride, chloroform, and
trichloroethene (TCE) are COPECs observed in the groundwater sample. The following
comments pertain to the Risk Assessment:
Ecological Risk Assessment (ERA):
1.For the Tier 1 screening level ERA (SLERA), the no observed adverse effect level
(NOAEL) toxicity reference values were used to calculate hazard quotients (HQs) with a
hazard index (HI) of 2. However, according to Table 1, several COPECs were not
retained as they were below screening levels. A simple point-to-point comparison of
screening levels is not an acceptable rationale for eliminating COPECs. As outlined in
Section 4.0 of the Division of Waste Management and Radiation Control (Division)
Technical Guide to Risk Assessment (TGRA), “An initial reduction of COPCs/COPECs
by a simple comparison to the RSL is not acceptable. All contaminants deemed present
due to site activities must be carried forward as COPCs/COPECs for comparison to
background, regardless of if the maximum detected concentration is less than the RSL.”
In addition, in accordance with Utah Administrative Code R315-101-5(j), all COPECs
identified should be retained and assessed for their respective hazard quotients (HQs).
Please revise Table 1 to include all COPEC HQs and update the HI accordingly.
2.Table 2 indicates TCE is calculated and determined to have a HQ of 0.2 which is below
the non-carcinogenic HI threshold of 1. However, Table 2 indicates that TCE should not
be retained because it is below the regulatory screening level. As mentioned in the
Division’s ERA Comment 1, a point-to-point comparison of screening levels is not an
acceptable rationale for eliminating COPECs. Please revise Table 2 to remove any
indication that the COPEC should be eliminated.
3.Screening levels were taken from the ECORISK database Release 4.2. Please note that
Release 4.3 (September 2022) is available. Release 4.3 does not include any updates to
the ecological screening levels (ESLs) listed in Table 1. No response is needed.
4.It is noted that the average of the parent and field duplicate sample was used as the
exposure point concentration (EPC). For future evaluations for the initial screening
assessment, the maximum of the parent and field duplicate should be used as the EPC.
Given the minimal difference between the parent and field duplicate, using the average
detection does not affect the overall conclusions of the assessment. No response is
needed.
5.In the Division’s initial comments, it was requested that a discussion evaluating the soil
exposure pathway from water spread across the site be included in the revised SLERA.
As outlined in the initial comment, COPEC impacted groundwater is spread across the
soil at the site for dust suppression and gravel washing, resulting in soil being a
potentially complete exposure pathway. Discussion of the soil exposure pathway to an
ecological receptor is warranted. Please update the Report to include qualitative
discussion of the soil exposure pathway and whether soil samples should be collected to
evaluate the impact to non-burrowing wildlife and shallow rooted plant receptors in the
top foot of soil.
Human Health Risk Assessment (HHRA)
1.In the Division’s initial comments, it was requested that a discussion evaluating the soil
exposure pathway from water spread across the site be included in the revised HHRA.
Based on the concentrations of constituents of potential concern (COPCs) identified in
the impacted groundwater combined with use of groundwater as an active dust
suppressant, soil may be considered a complete exposure pathway. Please update the
Report to include a qualitative discussion of whether soil should be included when
assessing exposure pathways for an outdoor worker. The groundwater risk assessment
results and volatile nature of the COPCs should be considered when evaluating whether
the soil is a complete exposure pathway and if subsequent samples are necessary to
evaluate risk from impacted soil.