Limited Expert Review of Probably Hydrologic Consequences and Ground Water Model Reports for Bull Mountain Mine Number 1 - AM6

Dr. W. Payton Gardner's review concludes that the PHC and GMR for the Bull Mountain Mine contain significant omissions and non-conservative assumptions. The review highlights a failure to quantitatively analyze impacts on over 50 local springs and shallow groundwater wells, a groundwater model that ignores fracture flow processes and incorrectly assumes 'healing' in mudstone layers, and a mitigation strategy relying on the UB2A sandstone aquifer that is likely insufficient in both volume and water quality.

• The PHC report fails to provide quantitative analysis of the risks to shallow water resources, including over 50 springs with seasonal discharges exceeding 1 gallon per minute (gpm). The author notes that some undermined springs no longer follow previous seasonal patterns or have stopped flowing, despite wetter conditions in 2022 and 2023.
• The groundwater model is criticized for using porous media parameterization instead of explicitly considering fracture flow, which likely leads to an underestimation of the hydraulic connection between the mine and the surface.
• The model relies on an untested assumption that mudstone layers thicker than 10 feet undergo 'fracture healing,' which the reviewer argues is not guaranteed for indurated clays and likely minimizes the predicted mining effects on surface reservoirs.
• The proposed use of the Sandstone UB2A deep underburden aquifer for mitigation is likely inadequate. A probabilistic analysis of 1,000 realizations suggests that a single well pumping at 6 gpm could cause a median drawdown of 60 feet at the mine boundary after 100 years, making it unlikely to meet the replacement demands for numerous shallow wells and springs.
• Mitigation water from the UB2A aquifer is likely of lower quality than the shallow water it would replace. The mean conductivity of UB2A water is 2605 μS/cm (Class III), compared to 1607 μS/cm for spring water and 1740 μS/cm for shallow overburden water (both Class II).

APA

Gardner, W. P. (2024). Limited Expert Review of Probably Hydrologic Consequences and Ground Water Model Reports for Bull Mountain Mine Number 1 - AM6. Earthjustice. https://earthjustice.org/wp-content/uploads/2025/06/gardnerphcreviewbull-mountainmine1-2.pdf

Chicago

Gardner, W. Payton. Limited Expert Review of Probably Hydrologic Consequences and Ground Water Model Reports for Bull Mountain Mine Number 1 - AM6. Earthjustice, 2024. https://earthjustice.org/wp-content/uploads/2025/06/gardnerphcreviewbull-mountainmine1-2.pdf.

Wikipedia

{{cite report |last1=Gardner |first1=W. Payton |title=Limited Expert Review of Probably Hydrologic Consequences and Ground Water Model Reports for Bull Mountain Mine Number 1 - AM6 |publisher=Earthjustice |date=12 July 2024 |url=https://earthjustice.org/wp-content/uploads/2025/06/gardnerphcreviewbull-mountainmine1-2.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{gardner2024limited, author = {Gardner, W. Payton}, title = {{Limited Expert Review of Probably Hydrologic Consequences and Ground Water Model Reports for Bull Mountain Mine Number 1 - AM6}}, institution = {Earthjustice}, year = {2024}, month = jul, url = {https://earthjustice.org/wp-content/uploads/2025/06/gardnerphcreviewbull-mountainmine1-2.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }