Ground water pathways related to reasonably expected to discharge

The SPCC Rule applies to facilities that could reasonably be expected to discharge into navigable waters (40 CFR §112.2(a)).  Does a facility need to consider ground water pathways when determining if a discharge of oil could reasonably be expected to reach navigable waters?

Owners and operators should consider whether on-site conduits such as groundwater pathways could facilitate the transport of discharged oil off-site to navigable waters.  Groundwater is often hydrologically connected to navigable waters; therefore, a ground-water oil plume has the potential to migrate and contaminate navigable waters.  Oil that repeatedly contaminates soil as a result of frequent spills may form subsurface oil plumes, which have the potential to contaminate navigable waters when precipitation migrates through soil to navigable waters.  Therefore, groundwater pathways should be included as a factor in determining a facility’s reasonable expectation to discharge.

Additional information for determining whether a facility could reasonably be expected to discharge to navigable waters is available on page 2-13 of the SPCC Guidance Document for Regional Inspectors (EPA 550-B-13-001).