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28-12 Groundwater Contaminant Exceedances at the Red Hill Facility: Analysis of Post-Spill Monitoring Data (2021–2025)

Session: Geoscience and Hydrogeology in the AI Era: From Predictive Models to Real-Time Applications (Posters)

Poster Booth No.: 110

Presenting Author:

Nenad Maric

Authors:

Maric, Nenad¹, Wu, Yanyan², Bartell, Scott³, Gribble, Matthew⁴, Pirkle, Catherine⁵

(1) Department of Ecological Engineering, Faculty of Forestry, University of Belgrade, Belgrade, Serbia, (2) Department of Public Health Sciences, University of Hawaiʻi at Mānoa, Honolulu, Hawaii, USA, (3) Joe C. Wen School of Population & Public Health, University of California, Irvine, California, USA, (4) Department of Medicine, Division of Occupational, Environmental, and Climate Medicine, University of California, San Francisco, California, USA, (5) Department of Public Health Sciences, University of Hawaiʻi at Mānoa, Honolulu, Hawaii, USA,

Abstract:

This abstract presents a secondary analysis of publicly available groundwater monitoring data from around the Red Hill Bulk Fuel Storage Facility (Site), accessed via the JBPHH Safe Waters website. The dataset includes 4,097 groundwater samples collected between November 2021 and March 2025, representing conditions observed throughout the Site’s monitoring well network. Since Red Hill Shaft (RHMW2254-01) was disconnected from the water supply network on November 28, 2021, these results do not represent tap water quality. Exceedances in groundwater were determined using threshold values (Environmental Action Levels established by Hawaiʻi State Department of Health) specific to each parameter, for example, 0.4 mg/L for the total petroleum hydrocarbon (TPH)–Diesel Range and 0.5 mg/L for the TPH–Oil Range. TPH-Diesel Range is the most common contaminant, with 198 exceedances across the Site, followed by TPH-Oil Range (80), 1-methylnaphthalene (31), benzo(a)anthracene (24), and naphthalene (19). Guideline exceedances were most frequent in late 2021, likely due to the fuel spill event. No exceedances of metals, alkalinity, and total dissolved solids were recorded in groundwater during the period analyzed. Spatially, TPH concentrations were unevenly distributed, with exceedances concentrated in a few specific wells. The highest number of TPH (combined Diesel and Oil range) exceedances occurred in wells RHMW02 (159), RHMW2254-01 (23), RHMW01 (17), RHMW04 (16), RHMW03 (13), and RHMW08 (13). The most recent exceedances were registered on: RHMW01 and RHMW02 (Mar-3-25), RHMW03 (Jul-16-24), RHMW04 (Jun-2-23), RHMW08 (May-11-22), and RHMW2254-01 (Nov-15-22). Although no exceedances have been recorded in the Red Hill Shaft since November 2022, and its extensive pumping has continued since January 2022, hydrocarbon contamination continues in nearby monitoring wells. RHMW02 stands out as a contamination hotspot, exhibiting the highest frequency and diversity of exceedances, including pre-2021 detections potentially caused by its proximity to the 2014 spill location. Reported TPH exceedances show seasonal variation (peaks in the spring and a decline in the fall) and might be influenced by groundwater recharge dynamics. However, the exact mechanism of contaminant mobilization is much more complicated, as Red Hill Shaft pumping affects groundwater flow and water table elevations at the nearby wells. Given the complexity of this basalt aquifer, characterized by considerable hydraulic conductivity anisotropy, detailed tracer studies are essential to accurately assess groundwater flow dynamics and contaminant transport pathways within the Site.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

Groundwater Contaminant Exceedances at the Red Hill Facility: Analysis of Post-Spill Monitoring Data (2021–2025)

Description

Session Format: Poster

Presentation Date: 10/19/2025

Presentation Room: Hall 1

Poster Booth No.: 110

Author Availability: 9:00–11:00 a.m.

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