Groundwater needs more attention and testing as well as soil. For one thing, an update is needed to reflect the conditions of both shallow and deep groundwater because of the length of time since the reported sampling, and after years of partial remediation. Contamination in groundwater aquifers does not stay in one place for years! I’m also concerned that the shallow and deep aquifers were presented as being separated by an aquitard, implying that the deeper drinking water aquifer was somehow protected from the high pollution in the more shallow areas. However, the shallow and deep aquifers are not continuously separated, leaving contamination to migrate between them. This is even more concerning since some shallow areas of the aquifer are very close to highly contaminated soil and thus very vulnerable to becoming more contaminated over time. Also, while pumping contamination out of the water has removed a lot of pollution, pumping also alters how quickly and in what direction groundwater (and contamination) moves, and may have increased the movement of contamination between these unconfined aquifers or how far from the refinery the contamination extends. Because of this, it would be prudent to conduct new tests as well as sampling a larger portion of both aquifers. The current work cannot be evaluated until all analysis about the aquifers is completed. Without that information, the public does not have all of the information to evaluate decisions on soil and groundwater sampling. Evergreen has not sufficiently delineated the nature and extent of contamination in the deep aquifer and the unconfined aquifer (water table).

Evergreen conducts continual groundwater sampling at the facility, not just as part of the RIRs.  Sampling is necessary before, during and after remediation is complete; therefore, sampling will continue at this facility for quite some time.  The current work under evaluation (what’s included in the RIRs) includes defining the nature and extent of contamination in the subsurface as well as significant information on the geology and hydrogeology, which do not require additional aquifer analysis to review.  Remaining aquifer analysis, which is the fate and transport model, takes the RIR data and predicts migration.  The eventual Final Report for the site will also include additional analysis to demonstrate that remediation goals have been attained, which will include further groundwater analysis of aquifer conditions.

The direction and rates of groundwater flow are evaluated frequently at the site and groundwater samples collected routinely from various hydrogeologic units beneath the facility. The Remedial Investigation activities also evaluated the areas where the confining layers in the subsurface were not continuous through the completion of soil borings, installation of monitoring wells, collection of groundwater samples, groundwater elevations and completion of aquifer tests to determine hydraulic properties of the groundwater units. These data will be used for the upcoming evaluation of contaminant movement in the fate and transport evaluation through the use of a 3-dimensional numerical model which will be presented in the Fate and Transport Remedial Investigation Report.

Characterization of the refinery geology, hydrogeology, and extent of contamination, including study of the pathways that could exist, has been ongoing and is included in the RIRs. A fate and transport analysis will be prepared once all the RIRs have been approved, and the analysis will include model simulations of contaminant transport. This report is expected to be submitted by the end of 2021.