W912PM22Q0039 Questions and Answers.pdf

Section reference Question

Appendix D: Sketches, Drawings, and As‐ builts

There are no drawings included for the former and/or existing stop logs. Can we obtain a drawing of the former/existing stop logs?

Appendix D: Sketches, Drawings, and As‐ builts

There are references in the Specifications section 06 90 00 for rubber seal materials and properties, however there are no drawings or descriptions for how these seals interface with the existing stop log slots, each other or surface of the stilling basin. Can we obtain a reference drawing of the existing rubber seals?

Statement of

Work/Design

Requirements

The language states the contractor should design and fabricate new stoplog slots, however there are no provided material specifications, dimensions, and minimal design requirements provided. Can we obtain some guidance for stoplog slot requirements? Is the intent that these are metallic or composite?

Specifications 06 90 00

Can the Engineer of Record be qualified to a European accredited organization or do they have to be USA accredited?

Specifications 06 90 00 page 7 and 17

Specifications state both Environmental and Marine tests are required. Can we propose materials that are certified by certification body such as DNV, Lloyds Register, or Bureau Veritas?

Design

What is the expected number of load cycles the stoplogs will experience during their lifetime of 100 years? And what is the typical duration of these load cycles?

As Built

What is the condition of the concrete plateau underneath the stop logs, assuming a straight crossing from one side wall pocket to the opposite side wall pocket? Good enough to seal on or in need of an (FRP) refurbishment?

As Built

Would the area directly underneath (downstream) this plateau be useable as a base for a thin but curved / arched stop log design? In terms of smoothness and in terms of load ability?

Design

Assuming a stop log design which is only slightly negatively buoyant, would there be a need to incorporate a mechanical locking mechanism to prevent flotation?

Design Is there any chance the stop logs would be impacted while in operation?

Could determine the stability requirements.

As Built

What is the max transport width for goods transported across the roads leading to the site of the stop log use? (could define the max product dimensions)

Design Would a hybrid made of FRP and steel structure be allowable?

Design Would a hybrid structure made of FRP, metal and concrete be allowable?

W. Kerr Scott composite stoplog and stoplog slots‐ W912PM22Q0039

As Built

What are the storage conditions foreseen for the stop logs? Is it allowed to store them vertically?

Or horizontally supported over the full length?

Is the storage location close to the dam and what type of transport is possible? Max dimensions?

Appendix C, par 1.2

“Limit the deflection of the stoplogs to L/360 in the horizontal direction and L/1000 in the vertical directions where L is the span length of the stoplog.” L/360 horizontal represents 2.00". If this is allowable (looking in a horizontal plane), than this deformation is also present in the vertical plane, there representing a 1/120 deflection with the vertical dimension of 20ft. Is perhaps meant to be said that the in‐plane horizontal deformation should be < 1/1000?

Specifications page

Is it required to use a bidirectional core or is that an option?

Installation/Design

Regarding installing/removing the stop logs: Is it allowed to have a person in the water while installing/removing the logs? To attach/remove hoisting equipment for example.

Installation/Design Would external, temporary, removable ballast be allowable to position the stop logs and hold them in place?

USACE Response

There are no existing stoplogs.

There are no existing rubber seals and the existing stop log slots will not be used, as they do not align anymore.

The slots can be steel or composite, the dimensions are not called out as they should be compatible with the stoplogs being designed. The slots should be designed to be bolted to the front of the stilling basin.

The Engineer of Record should be USA accredited.

Environmental and Marine testing is required, proposing a material that is certified by a certification body does not eliminate the need for testing.

Stoplogs will be used for periodic inspections and maintenance. Expected cycles will be roughly 30 for a 100 year life cycle. The duration of each cycle will be a week.

The concrete plateau has not been inspected and the condition can not be guaranteed.

The sill is not very wide, so an additional curb would have to be installed to accommodate a curved bulkhead.

We cannot say what the underwater conditions would be like.

A mechanical locking mechanism shall be used if the design indicates it is needed.

There is little to no chance the stop logs would be impacted.

The road leading to both the tailrace area and the maintenance yard support cranes and regular traffic. Keep in mind that a permit is required if, weight exceeds legal weight by NC law, total width is over 8'6", overall height is greater than 13'6", a single vehicle is over 40' or vehicle combination is over 60' in length, or (Exception: truck tractor/53‐foot semi‐trailer combination with no overall length limitation is allowed on all roads).

A hybrid structure is not allowed.

A hybrid structure is not allowed.

Stoplogs storage conditions will be in a maintenance yard until a storage rack can be built close to the tailrace area. The stoplogs can be stored vertically but will be laid down when delivered. The final storage location will be close to the tailrace area so that a crane can be setup and place the stoplogs directly from storage. The road leading to both the tailrace area and the maintenance yard support cranes and regular traffic. Keep in mind that a permit is required if, weight exceeds legal weight by NC law, total width is over 8'6", overall height is greater than 13'6", a single vehicle is over 40' or vehicle combination is over 60' in length, or (Exception: truck tractor/53‐

Yes, the limit should be that the in‐place horizontal deformation should be <1/1000.

It is not required, but an option.

A person can be used in the water to attach/remove hoisting equipment.

External, temporary and/or removable ballast will not be allowed to hold the stoplogs in place.