WY_FLSP_6WX(1)_Pavement_Memo.pdf

U.S.Deporrmenl ofTranspanarion Federal Highway Administration

Technical Memorandum

Subject: Pavement & Materials Final Recommendations WY FLAP 6WX(1), Southfork Road

From: Dan Sorensen Pavement & Materials Engineer , CFLHD

Date: January 28th, 2019

To: Micah Leadford Project Manager, CFLHD

INTRODUCTION:

This memorandum provides pavement and material recommendations for the Southfork Road Project from MP 27.8 to MP 35.3. The attachment to this memorandum includes the “Pavement Investigation WY FLAP 6WX(1), Southfork Road” by Engineering Associates Consulting Engineers and Surveyors. The tech memo includes, bore locations, asphalt and aggregate base thickness, and core pictures. Subgrade samples were also obtained and test results can be found attached titled “Central Federal Lands Highway Division Report of Soil or Aggregate Test”

DESIGN RECOMMENDATIONS:

The following pavement structure is recommended for the Southfork road.

3 inches HACP (401 bid item) 6 inches of Aggregate Base (May consist of pulverized pavement, aggregate base course or a homogeneous blend of the pulverized pavement and aggregate base. See SCRs 302 section for details.)

All borings performed within the roadway resulted in subgrades samples with A-1-b and A-2-4 material with high R-Values. As noted, the soil types consist of silty or clayey gravel and sand. R-values ranged from 33 to 72. Ground water was not encountered below the existing grade. Existing structural section of roadway to be pulverized consists of asphalt depth ranging from 0.75” to 5.5”, with aggregate base depth ranging from 6.0” to 10.50”. The overall structural section depth ranges from 10.1” to 13.8”.

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May 29, 2018

Mr. Dustin Robbins, PE Geotechnical Engineer FHWA – Central Federal Lands 12300 West Dakota Avenue Lakewood, Colorado 80228

Re: Pavement Investigation WY FLAP 6WX(1) Southfork Road

Dear Mr. Robbins:

Engineering Associates (EA) is pleased to submit this report for the Pavement Investigation on existing County Road 6WX Southfork Road, located approximately 25 miles southwest of Cody, Wyoming. The purpose of this study is to evaluate the pavement section and aggregate base thicknesses from Mile Post (MP) 27.8 to Mile Post

35.3. Pavement cores were taken approximately one per mile and alternated between westbound and eastbound lanes.

SCOPE OF SERVICES

EA’s services were performed in general accordance with the Short Form of Agreement between Owner and Engineer for Professional Services dated 05/23/18. EA’s Scope of Services consisted of the following:

• Perform eight cores/borings at selected locations within the paved areas.

• Determine the thickness of the existing pavement section (asphalt and aggregate base) materials at each core/boring location.

• Prepare a letter report, with photographs of the extracted core at each sample location, presenting the results of field and laboratory services.

SITE INVESTIGATION AND SUBSURFACE CONDITIONS

Eight cores were obtained at the approximate locations shown in the log below. The test locations were selected by Engineering Associates personnel.

The asphalt thicknesses reported below is the average value of three measurements obtained in the laboratory on each core sample rounded to the nearest 1/8 of an inch.

Photographs of the asphalt core samples are at the end of the report.

The crushed aggregate base course thickness measurement was performed after the pavement core was removed and the crushed aggregate base was removed until the sub grade was encountered. The depth of the hole was measured to the nearest 1/8 of an inch

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The following information was obtained during the investigation performed on existing County Road 6WX Southfork Road, approximately 25 miles southwest of Cody, Wyoming on May 24th, 2018.

Core Designation/Location Location

Asphalt Depth

(inches) Crushed Base

Depth (inches) Approx.

Lat Approx.

Long Westbound 1 MP 29.3 4.250 9.50 44.2623 -109.4825 Westbound 2 MP 31.3 2.125 8.50 44.2468 -109.5173 Westbound 3 MP 33.3 1.250 10.50 44.2287 -109.5367 Westbound 4 MP 35.3 0.875 10.25 44.2086 -109.5559 Eastbound 1 MP 34.3 0.750 9.38 44.2191 -109.5474 Eastbound 2 MP 32.3 4.250 6.00 44.2388 -109.5221 Eastbound 3 MP 30.3 3.375 10.38 44.2548 -109.5063 Eastbound 4 MP 28.3 5.500 7.50 44.2729 -109.4717

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LIMITATIONS

The information submitted in this report is based on the available information obtained by EA on existing County Road 6WX Southfork Road. The findings contained herein have been made in accordance with generally accepted engineering practices in the local area. This report has been prepared for the exclusive use of FHWA for the Pavement Investigation. No other warranties are implied or expressed. This report may be used by FHWA and Park County to help with their upcoming Geotechnical Investigation of the referenced project.

EA appreciates the opportunity to perform these services. If you have any questions pertaining to this report, or if we may be of any further service, please contact our office at 307-587-4911.

RESPECTFULLY SUBMITTED,

ENGINEERING ASSOCIATES

Cody Schatz, PE and LS Project Manager cc: Brian Edwards – Park County Engineer

Job No. 18009.18