Attachment_E_North_Fork_Bridge_Questions_and_Answers_0001.pdf

North Fork Bridge Questions and Answers

North Cascades National Park Service Complex

1. In the specs it states: Abutment concrete shall be test verified to be 2,500 PSI minimum prior to installing bridge anchor bolts and/or placing bridge on-site. Abutment concrete 28 day strength shall be test verified to achieve 5,000 PSI minimum.

Was the intention of that statement that the contractor has to wait the full 28 days, or that they need to test one of their cylinders to make sure they are at 2500 before they can set the bridge?

A: The intent of the specs is 2500 psi at 7 days, 5000 psi at 28 days, as a minimum. Relative to placing the anchor bolts and bridge, concrete must be at 2500 psi minimum. The specs indicate that should take 7 days.

2. Can we use a NON AISC fab shop but instead hire a third-party inspector to inspect and certify the work before shipment?

A: A non-AISC certified steel fabrication shop with experience in weathered steel, HSS, and bridge fabrication is acceptable. Third party inspection must be provided in conformance with AISC certification and standards. Welders must be AWS accredited per specifications. Contractor is responsible for implementation of quality assurance in conformance with specifications and industry standards. NPS will only be reviewing inspection records, not actively managing the quality assurance performance.

3. Please confirm that no NEW bridge lumber should be pressure treated??

A: Pressure treated lumber is NOT allowed.

4. There is a pile of scrap lumber from the washed out bridge. Is the contractor responsible to haul this material out at the end of the project?

A: Yes. Demolition of existing bridge components and packaging of loads is outlined in CLIN 2 and the backhauling of loads is outlined in CLIN 3 and 7.

5. Please confirm that only human and horse is allowed to transport man and materials via the trail network?

A: Confirmed. Only foot and horse transport on trails. No motorized or mechanized vehicles.

6. It appears that the existing south abutment must be removed completely in order to place new concrete footings. This south abutment is a significant portion of the structural components of the suspension bridge. By removing the suspension bridge, and awaiting 28 day cure on the concrete before the new bridge is placed, we are looking at closing access to the public to the bridge for at least 6 weeks.

Please confirm.

A: Guidance on concrete specifications and testing is addressed in Q&A #1. South abutment is not removed. New footing caps are to be added to the existing south abutment. Reference sheet S-001.

7. It is very likely that during excavation for the new footings we would encounter large boulders that cannot be moved by hand. Can the ER provide a detail for drill and epoxy rebar into the large boulders?

A: Reference G-002 Foundation Note 6. Intent is for rocks to be removed and/or broken to achieve foundations per plan. Should foundation excavations uncover immovable rocks, as verified by NPS inspection personnel, drilling and epoxy rebar dowels will be allowed. Rebar size and spacing per plan details will govern, with 4” minimum epoxy embedment. Foundation Note 6 will be updated as part of Revision 1 to include this provision.