C06 Amendment 1 Q-A Attachment_140R2021Q0031_0001.pdf

United States Department of the Interior

BUREAU OF RECLAMATION

California Great Basin Region

2800 Cottage Way

Sacramento, California 95825-1898

RE: 140R2021Q0031, Amendment 1, Questions & Answers Attachment

Q: Can all the CT’s we need to inspect be done with a JLG? Do we have enough room to get on in & out?

A: All the current transformers (CT) can be inspected with articulating boom man lift

(JLG)

Q: Do you know if Bureau of Reclamation (BOR) will change the workdays so we can work Saturday and/or Sundays? Will BOR change it so we can work 12-hr days?

A: BOR can accommodate 5X10 schedule M-F. Contractor will need to account for

Saturday and Sunday off working.

Q: What is the primary voltage rating on these transformers?

A: The transformers are all 13.8 kv as shown on the transformer leak photos attachment;

each plant specific label plate photo.

Q: Photo 8 SH-PP KU 1 C Phase 6 Bolt Flange – based on the photo it is difficult to confirm if there are alternate isolation points. In order to conduct this repair without a full drain, we need to know if there are isolation points beyond the flange, that can be used to allow for repair without drain. Can you confirm?

A: There is no other isolation point beyond the valve. This repair needs to use a method that does not require oil to be drained from transformer.

Q: Photo 14 KE-PP KU 1 4 Bolt Pump Flange – based on the photo, it appears there would be no way to isolate this flange to allow for repair without a full drain; it appears to be a bolt through valve, meaning we cannot remove to re-gasket, with oil in the main tank. Can you confirm?

A: Yes, this is a bolt through valve. This repair needs to use a method that does not require oil to be drained from transformer.

Q: Spring Creek Power Plant and Trinity Power Plant photos 17-26 seem to indicate the need for a full drain to conduct repairs. Is this consistent with BOR expectations, or is there a method of isolation not visible in the photos to allow oil to remain in main tank?

A: There is no other isolation point beyond the valve. This repair needs to use a method that does not require oil to be drained from transformer.

Q: Assumption on 8 bolt flanges, as they are connected to pumps, is that isolation from main tank possible to avoid full drain for those work scopes? Can you confirm?

A: Yes, these can be isolated if valve seals.

Q: For each location, is it possible to conduct the outages per transformer for either repairs or inspection, back to back on one mobilization? (i.e. all repairs and inspections for

Keswick on on trip, all repairs and inspection for Shasta on one mobilization, etc.)

A: Outages must be kept to a minimum to not restrict power generation and water distribution. The only leak outages will be authorized on one CT inspection to determine if they can be repaired at a later date. All other leaks can be repaired with an in-place repair method that does not require outage or oil to be drained.

Q: Does the dam have a transformer oil reservoir built-in so the oil from the transformer can be lowered?

A: BOR does not have any on-site capability to drain oil to an on-site reservoir. These systems were decommissioned years ago due to polychlorinated biphenyls (PCB) in tanks.

This PWS was written for an in-place repair method that does not require oil to be drained from transformers to repair leaks.