Arriba Rest Area - Advertisement - Appendix N - Structural Observation Report.pdf

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For t Co l l ins , CO 80524 p 970.484.7477 / in f o@f -w. com www. f -w.com

June 15, 2023

Mr. Karim Wahab

CDOT Architect I

2829 W. Howard Pl., 4th Floor, Denver CO, 80204

720.648.0141

RE: Arriba Rest Area

Exit 383, I-70, Arriba, CO 80804

Dear Mr. Wahab, On May 24, 2023, I performed a structural observation of the Arriba Rest Area Building to investigate cracks in the exterior walls, particularly at the back of the building, the north-west side of the building.

The rest area wall structure typically consists of 8” concrete masonry unit (CMU) bearing walls with insulation on the exterior face of the CMU and 4” exterior split-face CMU veneer. However, at the back of the building there are some alcove walls that are constructed of 8” split-face CMU exposed bearing walls that support a low roof. The roofs are metal standing seam. An overall view of the back of the building is shown in Picture 1.

The cracks at the back wall appear to have been caused by water infiltration into the CMU wall from the roof structure above and have widened over time due to freezing and thawing. See Picture 2 for a close-up of the biggest crack, which is up to a 1/4-inch wide on the east-most back wall. Cracks also occur on the inside of this wall behind the door, shown in Pictures 3a and 3b. These cracks are only 1/16” wide and are not as significant as the cracks in Picture 2. The vertical crack in the center of the wall in Picture

2 should be repaired with a pointing mortar for the full thickness of the cracked face shell. Where this crack is less than 1/8-inch wide it will need to be widened to at least 1/8-inch to make the repair.

Where the crack wraps around to the corner and at the cracks inside the alcove on this wall (shown in pictures 3a and 3b), these cracks should be sealed with an elastomeric sealant.

Also at the back of the building is the entrance to the pipe chase behind the restrooms. There are cracks in the veneer at the back wall at the entrance to the pipe chase on the east side, shown in Pictures 4 and

5. These cracks are also likely due to water intrusion from roof leaks and subsequent freezing and thawing. They should be repaired with an elastomeric sealant.

Picture 1

Picture 2

Picture 3a

Picture 3b

Picture 4

Picture 5

The entrance to the pipe chase is under the low roof, and the building bearing wall for the rear gable end wall is supported by steel angle lintels that span the pipe chase. There is evidence of significant water infiltration on the angle supporting the veneer, with consistent rust seen along the length of that angle. (See Picture 6a.) There is negligible rust on the angles supporting the CMU structural wall. It could be that the duct opening in this wall has a leak in it that has allowed water to infiltrate into the veneer of the wall. Or there could be a leak where the low roof intersects the veneer. Possible sources of water infiltration are noted in Picture 10. It is recommended to clean off the rust from the bottom of the angle supporting the veneer using a power tool, verifying that the rust damage is superficial, as it currently appears. Then the angle should be repainted with an exterior grade protective paint. If signs of delamination of the steel are encountered at this angle during the cleaning, please contact me for further repair recommendations.

Picture 6b shows a crack in the exterior wall under and beside the light switch that should be sealed with an elastomeric sealant. This was the only significant crack observed on the interior of the walls.

Picture 6a

Picture 6b

At the west-most wall at the back of the building there are some minor cracks at the base of the wall, which also appear to be due to water intrusion and subsequent freezing and thawing. These cracks should be sealed with an elastomeric sealant. See Picture 7.

Picture 7

In addition to observing the back of the rest area, I observed the rest of the building inside and outside.

No significant cracks were visible in the structure from the interior. On the exterior, no damage was noted at the roof, as observed from the ground, but some hairline cracks were observed in the exterior masonry veneer. Some of these cracks have been previously sealed and in some cases the sealant has cracked. These cracks are likely due to temperature changes, and they should be re-sealed with an elastomeric sealant to allow for future temperature-related movement in the brick veneer. These cracks do not pose a structural concern. See Pictures 8 and 9.

Picture 8

Picture 9

No evidence of foundation settlement or significant structural damage was observed. It is however recommended to repair and seal the cracks in the back wall to limit future moisture intrusion from rain on the side of the wall and discourage growth of the crack. It has not been determined where the source of the roof leak is, and this should be investigated as well. CDOT maintenance personnel have not been successful in discovering the source of the roof leaks, and it may be necessary to employ a roofing contractor to inspect the existing roof. If the source of the leak is not discovered, any crack repair done will be damaged in the future, so it is necessary to find the source of the leak and repair it.

Possible sources for the leak(s) are shown in Pictures 10 and 11.

Picture 10

Picture 11

In conclusion, none of the cracks observed pose a current structural safety concern at this time.

Recommendations for repair of the existing cracks and the rusted lintel have been noted in the preceding report. It is necessary to find the source of the water intrusion at the low roof at the back wall and repair all leaks, and a roofing specialist should be consulted for this. I hope that I have been of service to you in this matter and please do not hesitate to contact me with questions.

Thank you, Elizabeth Grau, PE

Engineering Manager

Farnsworth Group, Inc.