FY 2003 Mainstem/Systemwide proposal 200309200

Section 1. Administrative

Project location

Reasonable and Prudent Alternatives (RPAs)

Section 2. Past accomplishments

Section 3. Relationships to other projects

Section 4. Budget for Planning and Design phase

Task-based budget

Outyear objectives-based budget

Outyear budgets for Planning and Design phase

Section 5. Budget for Construction and Implementation phase

Task-based budget

Outyear objectives-based budget

Outyear budgets for Construction and Implementation phase

Section 6. Budget for Operations and Maintenance phase

Task-based budget

Outyear objectives-based budget

Outyear budgets for Operations and Maintenance phase

Section 7. Budget for Monitoring and Evaluation phase

Task-based budget

Outyear objectives-based budget

Outyear budgets for Monitoring and Evaluation phase

Section 8. Estimated budget summary

Itemized budget

Total estimated budget

Cost sharing

Reviews and recommendations

This information was not provided on the original proposals, but was generated during the review process.

Comment:

The proposal is technically excellent. The proposal meets most of the ISRP review criteria. It is based on sound scientific principles, it is consistent with the Council's Fish and Wildlife Program, it has clearly defined objectives (with appropriate tasks and methods), and it provides for monitoring and evaluation of its results through model verification. The proposal is claimed to meet a regional need in adapting and applying well-known methods and software to help the region better understand the benefits and consequences of spill events and to forecast the effects of changes in spillway configurations designed to reduce gas supersaturation (but see below).

The ISRP recognizes that Computational Fluid Dynamics (CFD) models are being used for many hydraulic applications, and it seems logical to try this technique here. The adaptation combines deterministic equations with limited use of statistical models to understand the magnitude and distribution of dissolved gases below spillways. The logic for the model seems good. The proponents are well qualified to do the work, and the collaboration (including a large cost share) between ENSR and the Corps is an excellent mix of interests, capabilities, and eventual users. The problem of modeling air entrainment in the plunge pool may be a particularly difficult one to solve. The basic concept that mass exchange of gas between bubbles and water is an equilibrium process where the history of bubbles entrained below the spillway in time controls the TDG below the spillway has a firm basis in physical science. The success of the modeling effort will be tested against the relatively abundant data at Bonneville Dam spillway, but Bonneville Dam may not be the best place to test this model. The ISRP would prefer further consideration (calibration, validation) of the model at other dams so that the model is not constrained by any peculiarities of Bonneville.

The ISRP has concerns, however, over the need for this model. The proposal states on page 1 that "To date, prediction of spill-induced TDG is based on empirical relationships developed from project-specific field data. These predictive relationships are only applicable for the range of project operations for which the field data were collected and are only valid for the existing spillway geometry." The proposal goes on to assert that there are no tools available for accurately predicting expected improvements prior to implementing changes in the field. However, existing models that use empirical data over a range of spillway operating ranges with prescient forebay conditions have already been developed and they use real data, real conditions and are calibrated sufficiently to predict the TDG behavior of spill scenarios expected over most operations. Field data have been collected in a designed program for more than 20 years, and must cover a wide range of project operations. This data might be used as comparison among designs or operations that would provide guidance in this regard. The ISRP reviewers remain skeptical that 3D computational fluid dynamics modeling can add much to the field data and analyses that have already been produced. The proposal could have provided a fuller discussion about the specific flaws or gaps in existing information that might be provided by a new mathematical model (that would need to have field data for input and validation).

The presentation and discussion clarified the distinction between the CFD spillway model and the existing water quality models that predict far-field TDG effects. These water quality models were completed by Battelle over the past 5 years (see Richmond et al. 1999 and others). The proponents need, however, to show how their near-field model will link with these existing far-field models.

In summary, the ISRP has specific information requests:

1. Describe how the CFD model could be linked to the existing far-field models so that the predictions could be compatible with existing monitoring station data.
2. Better justify the model development in light of existing empirical spill/TDG data. Some points to respond to: What specific flaws or gaps in existing empirical information call for this model? If the CFD Model plans are for new designs, this makes sense. However, aren't most spillways already fitted with TDG improvements (flip lips)? This would have been a valuable tool before the decision and commitment of funds to install flip-lips. Is this proposed because the Corps wants to rethink that decision? If this project is to model existing spillways and structures, it makes less sense. Is it to modify the existing spillways? Please explain what new structures are planned or contemplated and specifically how CFD modeling would benefit pre-design.
3. Describe how other dam spillways besides Bonneville could be used in the calibration/validation process to make the model less specific to Bonneville Dam.
4. Justify this expenditure as a BPA-funded project rather than as a Corps project, considering its close association with the hardware of a dam.

Comment:

Comment:

The proposal is technically excellent and meets the ISRP review criteria. It is based on sound scientific principles, it is consistent with the Council's Fish and Wildlife Program, it has clearly defined objectives (with appropriate tasks and methods), and it provides for monitoring and evaluation of its results through model verification. The proposal is claimed to meet a regional need in adapting and applying well-known methods and software to help the region better understand the benefits and consequences of spill events and to forecast the effects of changes in spillway configurations designed to reduce gas supersaturation (but see below).

The ISRP recognizes that Computational Fluid Dynamics (CFD) models are being used for many hydraulic applications, and it seems logical to try this technique here. The adaptation combines deterministic equations with limited use of statistical models to understand the magnitude and distribution of dissolved gases below spillways. The logic for the model seems good. The proponents are well qualified to do the work, and the collaboration (including a large cost share) between ENSR and the Corps is an excellent mix of interests, capabilities, and eventual users. The problem of modeling air entrainment in the plunge pool may be a particularly difficult one to solve. The basic concept that mass exchange of gas between bubbles and water is an equilibrium process where the history of bubbles entrained below the spillway in time controls the TDG below the spillway has a firm basis in physical science. The success of the modeling effort will be tested against the relatively abundant data at Bonneville Dam spillway. The proponents agreed to further consider calibration and validation of the model at other dams so that the model is not constrained by any peculiarities of Bonneville.

The ISRP concerns over the need for this model were adequately alleviated by the response. The proposal states on page 1 that "To date, prediction of spill-induced TDG is based on empirical relationships developed from project-specific field data. These predictive relationships are only applicable for the range of project operations for which the field data were collected and are only valid for the existing spillway geometry." The proposal goes on to assert that there are no tools available for accurately predicting expected improvements prior to implementing changes in the field. However, existing models that use empirical data over a range of spillway operating ranges with prescient forebay conditions have already been developed and they use real data, real conditions and are calibrated sufficiently to predict the TDG behavior of spill scenarios expected over most operations. Field data have been collected in a designed program for more than 20 years, and cover a wide range of project operations.

The ISRP reviewers were skeptical that 3D computational fluid dynamics modeling could add much to the field data and analyses that have already been produced. The response was helpful in explaining how the model might be useful as an adjunct to existing models, and in fact if properly developed and subsequently employed, might result in cost savings by reducing or even eliminating the need for continuing extensive monitoring of TDG. The "Benefits of the Proposed CFD Model" section of the response was particularly to the point. One could imagine a situation where periodic random sampling of TDG would suffice - once the model was verified.

The presentation, discussion, and response clarified the distinction between the CFD spillway model and the existing water quality models that predict far-field TDG effects. These water quality models were completed by Battelle over the past 5 years (see Richmond et al. 1999 and others). The proponents showed in their response how their near-field model will link with these existing far-field models.

In summary, the proponents do a good job of showing that this "first principles" CFD model can provide more information for design of low gas spillways than can the accumulation of monitoring data from user-specific and limited cases. They also are persuasive that not all structural modifications have been made on spillways that cause DGS and that the model will have uses. They clearly show that the Bonneville Dam case to be modeled was selected because of the wide array of empirical data for model validation/calibration, and not because of the greatest need to use it at Bonneville. The Bonneville case will be used to develop and test the model, and then it can be applied elsewhere where the needs are likely greater. The proponents adequately show how their model would be interfaced with the far-field models used for the basinwide modeling by providing tables of input values rather than direct linking.

Comment:

Comments
This proposal is not directly linked to an RPA Action. It would, however, increase understanding of total dissolved gas dynamics in the near tailrace zone, but these dynamics are already understood to a reasonable degree by near-field dissolved gas studies, and lessons learned from the Dissolved Gas Abatement Study (DGAS). The real challenge is to improve gas transfer predictability between the Bonneville spillway, and the Camas dissolved gas monitoring station - which has been only approximately defined. This study does not address those important issues. The study is redundant.

Already ESA Required?
No

Biop?
No

Comment:

Comments: