DSHW-2024-005606

April 2, 2024Edward Meeks
Remediation Project Manager
Hercules LLC.
500 Hercules Road, Building 8139/7
Wilmington, DE 19808-1599RE:2023 Groundwater Monitoring ReportFormer Hercules Bacchus Plant 3Approximately 5400 South 7000 WestWest Valley City, UtahDear Mr. Meeks:The Division of Waste
Management and Radiation Control has completed a review of the Groundwater Monitoring Report for October 2023(Report) prepared by Geosyntec Consultants for Ashland Inc. (Hercules LLC)
at the former Hercules Bacchus Plant 3 site. The Report includes a summary of the October 2023 annual groundwater monitoring event, field monitoring activities, sampling procedures,
groundwater analytical results, and data validation.
The Report also includes a statistical trend evaluation for the contaminants of concern at the site. The Report concludes that the groundwater plume is stable and decreasing and should
continue to decrease over time. Based on the resultsof the statistical trend analysis, the Report proposes to reduce the monitoring frequency from annually to biennially (every other
year). The next groundwater monitoring event will be conducted in October 2025.
The Report appears to be acceptable and is hereby approved. If you have any questions, please contact Hao Zhu at 801-558-9833. Sincerely, Douglas J Hansen, DirectorDivision of Waste
Management and Radiation ControlDJH/HZ/wac: Angela Dunn, Health Officer, Salt Lake County Health Dept. Dorothy Adams, Deputy Director, Salt Lake County Health Dept. Ron Lund, Environmental
Health Director, Salt Lake County Health Dept. Brian Smith, Geosyntec Consultants (Email)[e-mail] Meeks, Ashland Inc. (Email) ([e-mail])