DERR-2024-013246

DERR Comments for Draft Remedial Action Plan (RAP)
Redwood Road Dump VCP Site #121
5/30/2023
Terracon Response 6/13/2023
General Comments:
1.In the letter to the Salt Lake City Corporation dated February 9, 2023, the DERR provided
technical items to be included in the RAP. It appears that many of the items were not addressed
such as General Comment #3 below, called for in the VCP Remedial Action Plan Guidelines. To
complete the RAP, please review and address the comments in this document.
Missing elements include a Conceptual Site Model, a Schedule, and References. These have been
added to Sections 2.4, 10.0, and 11.0, respectively.
2.The text makes mention of the Utah Department of Environmental Quality (UDEQ). To avoid
confusion, please ensure that all project coordination is conducted with the Division of
Environmental Response and Remediation (DERR) project manager. Please change mentions of
“UDEQ” to “DERR” after the introduction in Section 1.0.
This has been changed throughout the document.
3.The EPA guidance should be used to develop a Conceptual Site Model (CSM) to address potential
exposure pathways for the site. Please include a CSM as a component of the RAP.
Added in Section 2.4.
4.Please add a section to define the anticipated project schedule.
Added to Section 10.
5.Please confirm that the vapor strategy proposed in the RAP has been reviewed with TOSA to
ensure the "air gap" vapor mitigation method, which has previously been discussed, is no longer
desired on-site. If the final vapor mitigation strategy has not been established, please include both
strategies (“air gap” and ANSI/AARST CC-1000 2018) in the RAP to address potential vapor
concerns on the site.
Addressed in Section 4.2; references to ANSI/AARST CC-1000 2018 have been changed to refer
more generally to industry standards.
6.Site Characterization identified hexavalent chromium reported above the Tap Water RSL in the
sample from TOSA-MW01. Please revise the text to indicate hexavalent chromium as a
Contaminate of Concern (COC) and include hexavalent chromium in the groundwater
monitoring.
Hexavalent chromium has been added as a COC (see Section 2.3) and will be included in
groundwater monitoring program (Section 7.5).
Specific Comments:
1.Section 1.0, page 1- The Voluntary Cleanup Program is implemented by the DERR, for the
UDEQ. Please revise the text to clarify.
Text has been revised.
2.Section 3.0, page 5, bullet #4- This RAP objective outlines a concern of storm-water originating
from the neighboring property that may migrate onto the site. Please revise the text to expand this
topic to include debris and sediment that may also migrate onto the site from neighboring
properties.
Text has been revised.
3.Section 3.1, pages 5&6- Cleanup or action levels for COC’s are established for the RAP. Some of
these cleanup/action levels are site specific goals rather than regulatory limits. Please revise the
text and define these numbers as “cleanup levels” or “action levels” rather than “regulatory
limits”.
Text has been revised in Section 2.3.
4.Section 3.1, page 6- Please reference the most up to date Regional Screening Level Summary
Table (RSLs) from EPA for May 2023 rather than November 2022. Values have not changed and
do not need to be adjusted.
Text has been changed to reference RSLs for May 2023.
5.Section 3.1, page 6- Please revise the text to add methane as a potential concern for the site
[action level for methane is typically the Lower Explosive Level (LEL) 5%].
Mention of methane as a potential concern has been added to Sections 2.3 and 2.3.4.
6.Section 4.0- Please add a section to define the remedial approach to keep stormwater, debris, and
sediment from running onto the site from neighboring properties.
Added as Section 4.3.
7.Section 4.0- Please add a section to define the remedial approach for impacted groundwater. For
example, “Impacts to the groundwater have been observed. Monitoring will be implemented to
establish seasonal groundwater trends over time and to confirm that vapor mitigation and
institutional controls restricting access to the groundwater will remain protective of residential
land use”.
Added in Section 4.5. Note that vapor mitigation is not related to the groundwater impacts at the
site, as the COCs in groundwater are not volatile compounds.
8.Section 4.1.1, 7- The purpose of confirmation sampling after removing impacted material is to
ensure that all impacted material has been sufficiently cleaned up and the exposure pathways
have been removed. Please revise the text to include confirmation sampling of the underlying soil
after excavating the impacted material.
Text added to indicate confirmation sampling of floor material and floor samples have been added
to Table 1.
9.Section 4.1.4, page 8- Confirmation sampling must include appropriate field and laboratory
quality control sampling. Please revise the text to state that QC samples will be collected in
accordance with the QAPP and submitted to the laboratory requesting a Level 3 or equivalent
data package including a case narrative.
Text has been modified in Section 4.1.4.
10. Section 4.2, page 8, Vapor intrusion design requirements defined in ANSI/AARST CC-1000
2018 are a component of the proposed remedial approach and need to be included in the RAP. Please
attach a copy of ANSI/AARST CC-1000 2018 to the RAP as an appendix or revise the
text to include the relevant design specifications. This comment is also applicable if the “air gap”
method noted in General Comment #5 is included.
A copy of the standard has been included as Appendix E.
11.Section 6.1, page 9- It is unclear from the text if permanent fencing will be installed on the
northern and western boundaries of the site after construction is complete. Due to the location of
the adjacent landfill, please propose barriers to prevent access to the landfill (not applicable to
roads or trail access).
Text revised in Section 6.1.
12.Section 6.2, page 9- All trucks carrying material onto public roads must be tarp covered to
prevent the spread of contamination. Please revise the text to address this comment.
Text has been revised in Section 6.2.
13.Section 6.3, page 10- Please revise the text to state that the Fugitive Emissions Control Plan
(FECP) will be monitored closely by the environmental professional. Conditions on-site will be
maintained to ensure there is no visible dust leaving the site and water trucks or other acceptable
dust suppression measures will be implemented to keep dust down as necessary.
Added to text in Section 6.3.
14.Section 6.6, page 10- This section needs to better define the purpose of the “hazard
communication training” for workers on-site that are not involved with the cleanup process.The
Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard
(HCS) must be renewed every two years. It is designed to protect workers by providing sufficient
information to recognize potential hazards and take appropriate protective measures. Only workers
with HAZWOPER training may enter areas with known potential for exposure. Please revise the
text to address this comment.
Text has been revised.
15.Section 7- Groundwater monitoring will need to be identified as part of the remedial approach.
Please revise the text and move the Groundwater Monitoring (Section 9.2) into the Site
Management (Section 7) and state that a Groundwater Monitoring Plan will be included as an
attachment to the Site Management Plan (SMP).
Text revised.
16.Section 7- In order to establish seasonal groundwater concentration trends, please propose at least
eight rounds of quarterly sampling. After the initial eight rounds of sampling are completed, the
applicant will review the stability of the groundwater contamination. Based on the findings, the
applicant may petition the DERR to adjust the groundwater monitoring plan assuring groundwater
conditions are stable and the remedial approach for groundwater is protective of the residential
land use. Please revise the text to address this comment.
Revised in Section 7.5.
17.Section 8.2, page 12- If the remedial process cannot remove impacted material from the site, Salt
Lake City Corporation will work with the DERR to determine if impacted soils may be left in-
place with appropriate cover material to eliminate exposure pathways. Appropriate cover material
specifications need to be defined in the RAP. Any impacted soil left in-place must be protective of
residential site use. Please revise the text to address this comment.
Addressed in Section 8.1.
18.Section 8.3, page 12- A Utah certified Asbestos Inspector must be on-site to visually inspect for
the presence of potential ACM from excavations that encounter municipal landfill debris. If
potential ACM is observed, work will be halted in the area and DERR will be notified. All
sampling and ACM abatement will be completed in compliance with the Division of Air Quality
(DAQ) Asbestos rules. Please revise the text to address this comment.
Text has been revised.
19. Section 9.0, page 13- The RAP completion report should include a discussion of data quality
assurance as well as documentation (weigh tickets and/or load counts) for all material leaving the
site including non-impacted material. Please revise the text to address this comment.
Text has been revised.
End of DERR EA Review Comments