DERR-2024-010074

July 19, 2024
Ms. Leigh Anderson
Utah Department of Environmental Quality
Division of Environmental Response and Remediation
195 North 1950 West
Salt Lake City, UT 84116
Re:Proposed Modification to the On-Site Groundwater Monitoring Program (Rev. 1)
Former General Electric Facility
130 East 1100 North
North Salt Lake, Utah
VCP No. C-102
WSP Project No. US-EI-WDP0033
Dear Ms. Anderson:
WSP USA Environment & Infrastructure Inc. (WSP), on behalf of the GE Vernova (GE) is
proposing to modify the on-site groundwater monitoring program for the Former GE Facility
located at 130 East 1100 North in North Salt Lake, Utah. The current monitoring program and
the proposed modifications are discussed below.
Current On-Site Program
The comprehensive site-wide groundwater monitoring program currently implemented at the
Site consists of quarterly gauging, sampling and analysis of the 22 monitoring wells installed at
the Site including MW-1 through MW-8, and MW-10 through MW-23. Groundwater has been
consecutively monitored on a quarterly basis since January 2022.
The groundwater samples collected during implementation of the current monitoring
program are analyzed for volatile organic compounds (VOCs) per EPA Method 8260C, arsenic
(total and dissolved) per EPA Method 6020B, and 1,4-dioxane per EPA Method 8270D Mod. In
addition, groundwater samples collected from monitoring well MW-7 are also analyzed for
total petroleum hydrocarbon-diesel range organics (TPH-DRO) per EPA Method 8015D.
WSP USA E&IS
216 Centerview Drive,
Suite 300,
Brentwood, TN 37027
[phone]
wsp.com
Proposed Modification to the On-Site Groundwater Monitoring Program (Rev. 1)
Former General Electric Facility
VCP No. C-102
WSP Project No.US-EI-WDP0033
WSP
July 19, 2024
Page 2
Groundwater samples collected from select monitoring wells including MW-2, MW-3, MW-6,
MW-12, MW-13, and MW-17, are also analyzed for monitored natural attenuation (MNA)
parameters including nitrate, iron (ferric iron and ferrous iron), dissolved iron, sulfate, sulfide,
methane, ethane, ethene, alkalinity, and chloride.
Proposed Modification to On-Site Program
The groundwater monitoring program conducted to-date has provided the information
necessary to delineate the extent and level of site-related impact to groundwater. The
groundwater COCs include five VOCs [1,1-dichloroethane (1,1-DCA), 1,1-dichloroethene (1,1-DCE),
1,4-dioxane, cis-1,2-dichloroethene (cis-1,2-DCE), and trichloroethene (TCE)], arsenic, and TPH-
DRO (at MW-7 only). The VOCs are considered the primary COCs with focus being on the wells
located along the downgradient property boundary, MW-15 through MW-19, to assess the
effectiveness of the proposed groundwater monitoring natural attenuation remedy. Analysis
of the VOC groundwater data collected to-date has demonstrated that the signature of the on-
site VOC plume is largely composed of cis-1,2-DCE, a daughter product of TCE biodegradation,
which provides strong evidence that natural attenuation of the chlorinated solvent plume in
groundwater is occurring at the Site.
TPH-DRO has been identified as a COC primarily at monitoring well MW-7 which is located in
an area of former TPH-impacted soil. The impacted soil was removed during the soil corrective
action implemented at the Site in 2023. Due to the soil removal action, MW-7 required re-
installation which was completed in August 2023. Three monitoring events have been
conducted since re-installation of MW-7 and TPH-DRO concentrations have decreased from 1.1
milligrams per liter (mg/L) in December 2022 to 0.37 mg/L in April 2024, and no further TPH-
DRO monitoring is proposed.
Based on research into the presence and concentrations of arsenic in soil in Utah, as well as the
extensive soil assessments and delineation activities conducted on-site, the presence of arsenic
in groundwater is considered to be naturally occurring due to the Site’s geological setting.
Evaluation of the total arsenic groundwater data indicates overall concentrations range from
2.1 “J-flagged” micrograms per liter (µg/L) (MW-23) to 110 µg/L (MW-18), with no known historical
industrial operational impacts of arsenic in groundwater at the Site. Based on the on-site
groundwater sampling results and regional arsenic groundwater conditions, it is proposed that
total arsenic will continue to be sampled on a modified basis as described below.
Based on the information presented above and in previous submittals of the Plume Analytics®
modeling results for VOCs in groundwater, WSP on behalf of GE, is proposing to modify the
groundwater monitoring program as follows:
Proposed Modification to the On-Site Groundwater Monitoring Program (Rev. 1)
Former General Electric Facility
VCP No. C-102
WSP Project No.US-EI-WDP0033
WSP
July 19, 2024
Page 3
Following completion of the 9th consecutive quarterly groundwater sampling event
(April 2024), groundwater monitoring will be conducted on a semi-annual basis.
Each of the 22 monitoring wells will remain in the groundwater gauging program to
allow for the continued evaluation of water levels and potentiometric surface. This will
also provide the opportunity to continue to assess the conditions of the monitoring
wells on a regular basis to confirm they are not damaged and/or to identify the need for
repair(s).
MNA parameters will no longer be collected at the Site as the Plume Analytics®
groundwater modeling has demonstrated the strongest line of evidence for natural
attenuation is the presence and relationship (e.g., concentrations, molar fractions)
between TCE and its daughter products.
Groundwater samples will be collected for laboratory analysis from MW-2, the source
well MW-3, MW-4, the background well MW-6, MW-11 through MW-13 in the southern
vacant vegetated area, and MW-15 through MW-19 along the western property
boundary on a semi-annual basis and analyzed for:
o VOCs per EPA Method 8260C; and
o 1,4-dioxane per EPA Method 8270D Mod/SIM
TPH-DRO will no longer be collected at MW-7 as it has been demonstrated that
concentrations have decreased below the screening level of 1.0 mg/L.
Total and dissolved arsenic will continue to be sampled and analyzed on a semi-annual
basis in the southern vacant vegetated area (MW-10 through MW-14) and along the
western property boundary (MW-15 through MW-19).
The proposed duration of the sampling program presented above will be discussed in the
Groundwater Remedial Action Plan Addendum.
The attached Figure 1 identifies the wells included for semi-annual sampling and wells for
gauging only.
Proposed Modification to the On-Site Groundwater Monitoring Program (Rev. 1)
Former General Electric Facility
VCP No. C-102
WSP Project No.US-EI-WDP0033
WSP
July 19, 2024
Page 4
We appreciate your consideration of these proposed modifications to the on-site groundwater
monitoring program for the Former GE Facility in North Salt Lake, Utah. Please contact Brad
Glisson at [e-mail] if you have any questions or comments regarding this report.
Respectfully submitted,
WSP USA Environment & Infrastructure Inc.
Bradley K Glisson, CHMM Sara B. Mathews, CHMM
AVP - Project Manager AVP – Environmental Scientist
Attachment
Cc: Damian Foti/GE
Bill Rees/UDEQ
Scott Everett/UDEQ