Re: Approval of Addendum to Revision 1 of the Corrective Action Investigation Plan for Corrective Action Unit 98: Frenchman Flat, Nevada Test Site, Nevada Federal Facilities Agreement and Consent Order

Comments 1.) In the first paragraph of the Introduction on page 1, the last sentence states that that, "Upon Completion of this work, an evaluation will be made to ensure that all issues have been resolved". This sentence is repeated as the last sentence on page 7. It is NDEP's position that the issues that need to be resolved are those issues that are defined in Section 1.3, Summary of Draft Frenchman Flat CAU Model Review.

2.) Section 5.3.3 Proposed Modeling Activities covers the proposed options for additional modeling work. This section states that the direction that modeling activities will take depends on the outcome of the data collection and analysis work to be performed. It is stated that; "If the new data are in agreement with the draft CAU groundwater flow and transport model, the new data may be used to verify this model". This is followed later in the section by the statement; "Alternatively, if the new data are not in agreement with the draft CAU groundwater flow transport model, the data will be combined with the data used previously for reassessment". This appears to contradict the current UGTA strategy. Under the strategy NDEP found, after having conducted its own review and supported by the findings of NNSA/NV's external peer review, that the existing data were not adequate to support the development of an acceptable CAU flow and transport model.

The external peer review panel recommended two categories of actions that could result in more defensible predictions: 1) additional data through field work and laboratory analysis and 2) alternative modeling strategies. They also concluded that neither category would be sufficient by itself. The addendum was developed to address the identified data and modeling inadequacies. The necessary work includes data collection, evaluation, subsequent reassessment of data adequacy, the implementation of alternative modeling strategies, and a determination of the path forward. This addendum appears to allow NNSA/NV to inappropriately move past steps in the strategy and present to NDEP the original model without augmentation, and declare it "verified" without any additional modeling.

The NNSA/NV must follow the process outlined in the current UGTA strategy. New data will be collected in accordance with this addendum. This new/existing data will be evaluated and will include NDEP review and input. Then a determination must be made as to the data adequacy prior to revising the draft CAU flow and transport model and/or implementing alternative modeling strategies.

In addition, the approach of deciding for what purpose the data are to be used after they have been collected and assessed is not entirely in keeping with a Data Quality Objectives (DQO) approach. This approach dictates that prior to implementation, data uses must be clearly identified and proposed data collection activities be developed based on the questions to be answered or data gaps to be filled.

3.) In the second paragraph of the section titled Develop Conceptual Models under Section 5.4.2, the last sentence states, "… multiple conceptual models may be developed based on the same data." NDEP expects that if realistic alternative models can be developed, then NNSA/NV must make every effort to develop and investigate those alternative conceptual models.

4.) The Total-System Model approach that has been proposed appears to be an innovative method for investigating alternative conceptual models and assessing model uncertainty. It is unclear, however, if the output from this model will be purely qualitative or if it will have some quantitative component. Further explanation of how the Total-System model will be linked to the two proposed local models and the CAU-scale groundwater flow and transport modeling work needs to be presented to NDEP as the modeling work progresses.

5.) On page 51 in the 3rd paragraph a reference is made to the UGTA QAPP 2000. NDEP has not formally approved this QAPP. NNSA/NV must reply to the NDEP letter dated September 20, 2000 regarding this QAPP, which asked for further definition of the purpose of the UGTA QAPP and the application of the DQO process to the UGTA Project. More directly, NNSA/NV must state if the UGTA QAPP is a general guidance document or a specific QAPP for UGTA investigation activities.

While NDEP is not requiring a strict application of the DQO process, the UGTA Project must follow a defensible systematic approach based on the scientific method. Specifically, in future documents, the NNSA/NV must continue to clearly identify the question to be answered that requires the collection of new data. Data collection should be planned using a systematic planning process based on the scientific method. The plan should clearly define what data and information are needed and present a data collection design to obtain the correct type, quantity, and quality of data to make a defensible decision.

Sincerely,   Paul J. Liebendorfer, P.E. Chief Bureau of Federal Facilities