Questions and Answers_03 Sep 2020.pdf

Question and Answer Clarifications Wave Flume Generators

03 September 2020

1. Does ERDC assume responsibility for the strength of the concrete flume walls? Yes, as designed.

2. What maximum vertical force can we exercise on the wall top? Provided the structural drawings of the flume a mounting solution should be found given the wave generator design that doesn’t damage the flume.

3. Is there any restriction on the wave machine length, in front of and behind the paddle midstroke? The flume has a 6 meter section from the wall where the generators can be installed.

4. Is there a particular location planned for the paddle midstroke position, for example where the walls are flat enough? The walls are plumb and square, but if a specific requirement/specification is needed that should be provided in the package submission.

5. Both wave machines are adjacent; is a forward offset possible? A forward offset is possible as long as they remain in the 6 m length from the back wall.

6. Is there a minimum requirement for the wave component periods to be generated? For example in a second-order spectrum with peak period of 1.5s, this could be 1.5/2.5/2=0.3s. Solitary waves may require smaller values. (This would influence machine stiffness.) Surface tension will become more important for the dispersion 0f waves with a period at or below 0.33s thus wave generation below this period is not targeted. Peak period for spectra will never be targeted below 1s but may require a portion of the spectral tail to be cutoff. User defined high frequency cutoff is typical.

7. Is there a minimum requirement for machine lifetime in running hours and years? The mechanical components should be able to operate 1000 hrs per year over 20 years in the specified environmental conditions. Communication systems/protocol components are expected to last 15 years before requiring migration to a new standard.

8. Is there a maximum requirement for maintenance effort? Typical monthly machine maintenance and/or after 160 hrs of is expected. This would include lubricating parts, visually inspecting components and cleaning. The system may require more detailed maintenance depending on hours of operation and time. Maintenance will be handled by the USACE. Training on the maintenance procedures should be included as part of the on-site training.

9. Are these wave generators operated always separately or will they also work from time to time together and consequently the control systems must work together too? They should be able to operate at the same time but do not need to operate in a coordinated effort meaning they can have two separate control systems.

10. The performance of the ARC is not mentioned, does it mean that any performance will be accepted? ARC performance is dependent on wave frequencies and wave generation type (regular vs sea state vs solitary). However the industry is regularly demonstrating generator absorption performance of wave frequencies between .2 Hz and 1.2 Hz during dedicated wave paddle reflection test at rates between 85 and 90%. We expect this wave generation system to have a similar performance to that currently available at many testing locations worldwide.

11. The specification asks for a framework and racks of wave generator made of stainless steel and/or aluminum. Is this a requirement from a lifetime point of view, or is this required due to other reason such as the applied water quality? If this is a lifetime aspect, we suggest using steel with a coating and stainless steel construction, which has proven to be reliable for more than 20 years. Aluminum introduces other restrictions, which are probably not required too. The placement of these systems are in a metal building that doesn’t have any HVAC. This results in high humidity levels which can be problematic for steel components over the lifetime of the generator. The framework should be in compliance with the “Mounting” sections of the requirement within the DOR.

12. What is the reason for specifying the stroke of the wave flap? The wave performance does not require such a stroke. Is this because of the ARC? If so, could you please indicate the ARC performance you would like to approach with such stroke? See above.

13. Are there any accuracies required with respect to positioning, or wave performances?

The DOR provides a specification for wave generation performance. The machine positioning and performance should be repeatable. Current repeatability for spectral significant wave height generation is 1.5% maximum. The new system should perform better than this. Industry standards are expected.

14. Is there a list with technical evaluation criteria for the proposal, and how they are rated?

Per the Combined Synopsis Solicitation, this will be Lowest Price Technically Acceptable. All proposals submitted will be evaluated for Technical Capability, Past Performance, and Price. Please see the Combined Synopsis Solicitation for further details.

15. What power (voltage/frequency) is available at site? Is there any current limitation? 150 amp – 480 volt 3 phase is currently available. Additionally power needs can be accommodated. The current transformer has additional unused capacity.