Credibility of DOE RBAS Review of the
Hazards of LEHR Site Waste Constituents

October 15, 1997

Julie Roth, Exec. Director
DSCSOC
Route 2, Box 2879
Davis, CA 95616

Dear Julie:

I have received the October 10, 1997 letter from Susan Timm to Susan Fields regarding "Draft Final Determination of Risk-Based Action Standards (RBAS) for DOE Areas, Laboratory for Energy-Related Health Research, Solano County." From an overall perspective, I strongly support Susan Timm's assessment of the reliability of the DOE's approach for determining risk-based action levels where she states, "...models are predictive tools based on assumptions which are not necessarily accurate."

Ms. Timm states,

"If DOE proposes leaving concentrations of contaminants in the soil at levels greater than background, model predictions must be verified by monitoring groundwater for those contaminants downgradient and in close proximity to the soil contamination."

As you may recall in my previous comments on the DOE's proposed approach for vadose zone modeling, I made it clear that the models that have been used have limited reliability in predicting actual transport. These models are based on assumptions, such as average moisture content over the year, which have been known for over 15 years to be an unreliable basis for estimating the transport of constituents in the vadose zone. Also, there is a significant problem that DOE has not yet addressed which I have raised previously of the predicted hundred-year transport of nitrate in the soils at the LEHR site from the surface of the soil to the water table located 30 feet below the surface. This prediction is obviously significantly in error based on the fact that there is widespread pollution of groundwaters by ag-derived fertilizers that has occurred in a much shorter period of time than that predicted by the model.

It is my recommendation to DSCSOC that DSCSOC vigorously oppose any attempt by DOE to use the models as the only tool to assess whether constituents in waste management units and/or soils surrounding these units have migrated or could migrate to the water table and thereby represent a threat to groundwater quality. A key component of any attempt to leave constituents at the LEHR site above background will be actual field monitoring to verify that the predicted transport is, in fact, occurring. This will require a substantial array of unsaturated as well as saturated monitoring devices/wells that is operated over a considerable period of time.

With respect to S. Timm's comments on the need to revise the RBAS document, it should be understood that the current document is not a credible discussion of issues and should be recognized as being significantly deficient. If DOE wishes to incorporate appropriate discussion of these issues in future documents, then DOE should accept the characterization that the RBAS document is unreliable. Under these conditions, I would recommend that DSCSOC accept S. Timm's recommended approach. If there is any attempt on the part of DOE, however, to claim that the RBAS document as currently formulated has significant credibility, then DSCSOC should make it clear to DOE that DSCSOC will take appropriate action to ask for higher level review of this DOE document.

In the event that DOE or others claim that there is significant credibility with the current RBAS document, they should be reminded that DSCSOC has provided detailed comments on the significant deficiencies in DOE's approach toward estimating the hazards of constituents at the LEHR site. DOE has not responded to the many problems that DSCSOC has found in the RBAS document.