645-DOTRFQ-2927-2027 Amendment 1.pdf

IOWA DEPARTMENT OF TRANSPORTATION

ARCHITECTURAL SERVICES / RESOURCES & ACQUISITION BUREAU

800 Lincoln Way Ames, Iowa 50010 www.iowadot.gov

Amendment #1

For Ottumwa Salt Dome Repair

645-DOTRFQ-2927-2027

Amendment Pages: 8 ½” x 11” – (1) Amendment Attachment Pages: 11” x 17” – (1)

Date: 08 03 2026

Project: D5 – Ottumwa Dome Repair Project Number: BG-4T23(001)—80-90

Bid Date: 08-11-2026

TO ALL HOLDERS OF DRAWINGS AND PROJECT MANUAL:

See Purchasing Terms and Conditions for Bid Process.

PROJECT DRAWING CHANGES:

REVISED PROJECT SCOPE PDF (page2): See attached.

Repair Procedure for Hail Damage on AWS HD Acrylic Roof Membrane

Cut Back Damaged Coating

At each hail hole:

• Use a knife to cut back to solid, well-bonded coating.

• Remove fractured acrylic and any loose crushed insulation.

• If insulation is water-soaked, cut out wet material until you reach dry, rigid insulation.

Fill the Hole or Depression

For AWS HD acrylic systems, use acrylic mastic compatible with the AWS membrane.

• Trowel or knife-apply the mastic into the void.

• Fill the hole slightly proud of the surface.

• Allow initial set (usually 20–60 minutes depending on temperature).

If insulation was missing or deep:

• You can insert a piece of polyiso or foam filler to rebuild thickness first, then cover with mastic.

Embed Polyester Reinforcing Fabric (if hole is >1 inch)

For larger punctures:

• Brush or trowel a layer of acrylic mastic.

• Place polyester fabric into the wet material.

• Smooth it flat, ensuring full saturation.

• Apply a second coat of mastic over the fabric.

Polyester is required (not fiberglass), because it allows stretch with the acrylic membrane.

Apply High-Build Acrylic Topcoat

Once the repair is dry:

• Apply AWS HD acrylic topcoat to restore membrane thickness (typically 20–40 mils wet).

• Feather edges into surrounding membrane.

• Make sure there are no pinholes.

Allow Full Cure

• Acrylic membranes cure by evaporation.

• Avoid ponding water during cure.

• Typical cure time depends on humidity and temperature (1–4 hours surface dry, longer to fully cure).

Project Scope

It is mandatory that the Contractor make a site visit and inspect the damage for themselves prior to bidding and work.

Contractor to Clean and Prepare Dome roof per manufacture, Install Seam Seal to all hail damaged areas, verify number of coats required. Apply base and topcoat of AWS Acrylic over roof at a rate of 1.25 gps in 2 coats.

Inspect Roof System again after repairs to ensure all damaged areas were repaired. Provide a 10 Year warranty on roof system to cover labor and material.

Work shall include all materials, labor, equipment, and proper disposal of all debris.

Ottumwa Salt Dome Repair

BG-4T23 (001)-80-90

222-Jun-26 jsheph1 Line jsheph1 Line jsheph1 Line jsheph1 Text Box A repair in 2013 is believed to have been done with Neogard Permathane II System. Contractor is to confirm existing system (coating and insulation) and provide a compatible repair. Inspect coating and underlying foam. Cut out compromised sections, reapplying compatible foam if depth requires and recoat the repair area with compatible coating layers; base and topcoats at a rate of 1.25 gps in 2 coats.

jsheph1 Line jsheph1 Line jsheph1 Text Box compatible jsheph1 Text Box requirements.

jsheph1 Text Box coating jsheph1 Line jsheph1 Text Box Feather into the adjoining sound coating.

jsheph1 Line jsheph1 Line jsheph1 Text Box existing system.

jsheph1 Text Box coated jsheph1 Text Box Contractor to confirm insulation compatibility.

jsheph1 Callout polyurethane,