Maintaining the groundwater level is crucial to prevent gas leaks from storage tanks during the construction and operation of underground liquefied petroleum gas (LPG) storage facilities. At the Namikata National LPG stockpiling base in Ehime Prefecture, Japan, deionized seawater is continuously injected into the subsurface as part of a seal water system. This process introduces mixing between injected water, groundwater, and seawater with varying chemical compositions, potentially leading to supersaturation of dissolved components and subsequent mineral precipitation within fractures, which may reduce the permeability of surrounding geological formations. Once a fracture becomes clogged, the groundwater flow pattern changes, and there is a risk that gases will move to shallower areas. In this study, the properties of precipitates (scales) formed in tunnel spring water at an underground LPG storage facility under construction were investigated to assess their implications for groundwater flow sustainability. The analyses included measurements of precipitation rates of calcium carbonate calcite preparations, bacterial surveys, and column flow tests simulating geological conditions to evaluate changes in permeability of tunnel spring water and seal water. The results showed that scales consisted of calcium carbonate, Mn oxides, and Fe oxides. Column flow tests using seal water demonstrated reduced water flow rates caused by Fe oxide precipitation, mainly associated with Fe rust released from pipe corrosion. By applying a geochemical clogging model to these flow rate reductions, we clarified the relationship between iron concentration in seal water and changes in permeability, and were able to propose measures such as replacing piping materials, thereby contributing to clogging prevention.
No takes yet. Share an insight, caveat, or question.
Yoo et al. (2026) studied this question.
Synapse has enriched 5 related papers. Consider them for comparative context: