Qustions_and_Answers_3.pdf

12010919R0006 HOONAH FISH PASSAGE AND SAFETY IMPROVEMENTS

QUESTIONS AND ANSWERS #1

Q1. Timber notes on sheet A1 of the plans call for “GLUED LAMINATED MEMBERS MUST CONFORM TO THE CURRENT NATIONAL DESIGN SPECIFICATIONS FOR WOOD CONSTRUCTION (NDS), COMBINATION SYMBOL 5, WITH AN INDUSTRIAL APPEARANCE AND FABRICATED FOR WET USE, USING RESORCINOL GLUES.” Timber notes on sheet B1 echo the same Combo 5 but specifically refer to only “DECK PANELS”

Combo 5 beams are typically used in applications where loadings require significant strength such as the deck panels of a structure and not for sills and abutments. Are all beams including backwalls, sills, and bearings required to be Combo 5, or can glu-lam beams other than deck panels be Combo 3 or 24f-v4?

A1: Backwalls, sills, and bearings may be constructed using Combo 3 or 24f-v4 members.

Q2. Timber notes on A1 require abutment members to be treated “…AWPA UC4B (GROUND CONTACT, HEAVY DUTY) USING COPPER NAPHTHENATE.” Similarly, timber notes on sheet B1 require deck panels to be treated “…WITH AWPA UC3B (ABOVE GROUND, EXPOSED) USING COPPER NAPHTHENATE.” However, sheet B11 “APPROACH GUARDRAIL NOTES” requires “…PRESSURE TREAT ALL TIMBER IN ACCORDANCE WITH AWPA Ul, USE CATEGORY UC4A.”

This permits any preservative listed in the referenced AWPA Standards to be used and does not specifically require the use of Copper Naphthenate as for the glue-laminated beams. The availability of Copper Naphthenate preservative treatment is extremely limited in the western United States and there are other oil-borne preservatives available under the same AWPA Standards that can be used to meet either the UC3B, UC4A or 4B use categories. Will other oil-based preservative treatments such as Penta- A be allowed for treatment of the glue-lams?

A2: Provided that the relevant AWPA Standard for the given use (UC3B, UC4A, or UC4B) is adhere to, other oil-based preservatives are acceptable. Please note that other preservative formulae may pose exposure risks to workers and the environment that must be managed in accordance with US Environmental Protection Agency requirements.

Q3. Some of the structural steel components are too large to galvanize. Is metallizing acceptable?

A3: Metallizing is acceptable for components too large to galvanize provided the contractor submits an acceptable plan to field repair components whose finish is nicked or scraped during transport or installation.

Q4. How many girders are in the bridge?

A4. The drawings show 3 girders. The Forest Service is open to other (alternate) designs, but alternate bridge designs would need an engineer’s stamp. Most of our standard designs for shorter bridges have 4 girders, but not the 112’ bridge shown in the plans for this package.