UT NP ARCH 100(2) Bridges on Delicate Arch Road Pavement Memo.pdf

Memorandum

Subject: UT NP ARCH 100(2) Bridges on Delicate Arch Road Existing Structural Section Thickness Investigation

Date: April 29, 2024

From: Ron Andresen

Materials Engineer

To: Jim Kerrigan, PM Jeff Felling, Designer

Background:

This memorandum provides a summary of the existing structural section layer thicknesses needed for calculating full depth reclamation quantities for the upcoming project.

The project was drilled Jan 17, 2024. The company used for the drilling was QC Testing, Vernal Utah. A small excavator with a 6 inch auger was used to drill through the pavement. The project is 1.3 miles long. It begins at station 11+31 on Delicate Arch Road, where the previous 2017 Arches 10(2) project ended. This project includes new bridge construction, 1.3 miles of road reconstruction, and reconstruction of the Wolfe Ranch parking lot and the Lower Delicate Arch parking lot.

Findings:

Eleven holes were made in the roadway. The depth of each hole was approximately two feet. Deep enough to get through the existing pavement and base layer.

Two holes were made in Wolfe Ranch parking lot.

• Wolfe #1 was made in the parking area close to the roadway.

• Wolfe #2 was done in the parking area further from the roadway, about where the restrooms are located.

Two holes were made in Delicate Arch parking lot.

• Delicate #1 was made as you enter the parking lot, in the west part of the parking area.

• Delicate #2 was made at the east end of the parking area near where the foot trail to Delicate Arch begins.

The remaining seven holes are in the roadway, beginning at the station 13+80, and proceeding west to the end of the project. Holes were made in alternating lanes, in the middle portion of each lane. The table below shows the specific hole information.

Hole Information Hole

Number Location Existing Asphalt Thickness (in)

Existing Aggregate Base Thickness (in)

Hole #1 Station 13+80, centerline 4.0 6

Hole #2 Station 21+90, eastbound 4.5 6

Hole #3 Station 27+20, westbound 3.5 6

Hole #4 Station 37+70, centerline 4.5* 6

Hole #5 Station 53+60, centerline 5.0* 6

Hole #6 Station 69+40, westbound 5.0* 6

Hole #7 Station 74+70, eastbound 4.5* 6

Wolfe #1 Area closer to roadway 2.5 6

Wolfe #2 Area further from roadway 3.0 6

Delicate Arch #1

West side of Parking lot 4.0 6

Delicate Arch #2

East side of parking lot 4.0 6

* It appears there is a ½ inch thick chip seal from Wolfe Ranch to the end of the roadway at Lower Delicate Arch parking lot.

Observations:

The existing roadway asphalt thickness is approximately 4 inches from the beginning of the project to the Wolfe Ranch parking area entrance. After the Wolfe Ranch parking area there is a ½ inch chip seal applied to the pavement. The overall asphalt thickness of the existing roadway from the Wolfe Ranch parking area to the end of the road at the Lower Delicate Arch parking area is 4.5 inches.

Below the asphalt there is a granular layer of aggregate base like material approximately 6 inches thick. This material was found in all the hoes in the roadway and in the parking areas. This appeared to be drainable granular material.

Recommend doing full depth reclamation 6 inches thick. This will capture all the existing asphalt and mix in some of the aggregate base like material. It will also lease some of the aggregate base like material undisturbed and we will not get into any underlying clay material that might be below the granular material.

Recommendations:

• 4 inches of asphalt pavement placed in two lifts

• PG asphalt grade 76-22

• Pulverization depth of 6 inches for the roadway

• Pulverization depth of 6 inches for both parking areas

If you have any questions, please let us know.

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